Science.gov

Sample records for plasma deposited heparin-like

  1. Heparin-like anticoagulant associated with systemic candidiasis.

    PubMed

    Horne, M K; Chao, E S; Wilson, O J

    1990-09-01

    A 15 year old girl with aplastic anemia developed a heparin-like anticoagulant during the course of systemic candidiasis. This was initially detected in the laboratory by an elevation of the thrombin clotting time which corrected with toluidine blue but not by mixing with normal plasma. In vivo and in vitro the anticoagulant was remarkably resistant to neutralization by protamine sulfate. Nevertheless, its heparin-like nature was confirmed by its sensitivity to heparinase and its dependence on antithrombin III.

  2. Preparation of heparin-like surfaces by introducing sulfate and carboxylate groups on poly(ethylene) using an argon plasma treatment.

    PubMed

    Lens, J P; Terlingen, J G; Engbers, G H; Feijen, J

    1998-01-01

    Carboxylate and sulfate groups were introduced at the surface of poly(ethylene) (PE) samples. This was accomplished by coating and immobilizing sodium 10-undecenoate (C11(:)) and 10-undecene sulfate (S11(:)) on the polymer by means of an argon plasma treatment. The composition of the coated surfactant layer was proportional to the composition of the coating solution. The thickness of the surfactant layer on the surface of PE samples, which were precoated from an aqueous solution with a total surfactant concentration of 0.30 M, was about 55 A. The presence of carboxylate and sulfate groups after plasma treatment of the precoated surfaces was confirmed by X-ray photoelectron spectroscopy (XPS). About 20% of the initial amount of functional groups of the coated surfactants was retained at the PE surface. The ratio of carboxylate/sulfate groups at the plasma treated surfaces was dependent on the composition of the precoated surfaces. The minimum surface density of these groups on the resulting samples was about one group per 40 A2.

  3. Heparin-like entities from marine organisms.

    PubMed

    Colliec-Jouault, S; Bavington, C; Delbarre-Ladrat, C

    2012-01-01

    Polysaccharides are ubiquitous in animals and plant cells where they play a significant role in a number of physiological situations e.g. hydration, mechanical properties of cell walls and ionic regulation. This review concentrates on heparin-like entities from marine procaryotes and eukaryotes. Carbohydrates from marine prokaryotes offer a significant structural chemodiversity with novel material and biological properties. Cyanobacteria are Gram-negative photosynthetic prokaryotes considered as a rich source of novel molecules, and marine bacteria are a rich source of polysaccharides with novel structures, which may be a good starting point from which to synthesise heparinoid molecules. For example, some sulphated polysaccharides have been isolated from gamma-proteobacteria such as Alteromonas and Pseudoalteromonas sp. In contrast to marine bacteria, all marine algae contain sulphated wall polysaccharides, whereas such polymers are not found in terrestrial plants. In their native form, or after chemical modifications, a range of polysaccharides isolated from marine organisms have been described that have anticoagulant, anti-thrombotic, anti-tumour, anti-proliferative, anti-viral or anti-inflammatory activities.In spite of the enormous potential of sulphated oligosaccharides from marine sources, their technical and pharmaceutical usage is still limited because of the high complexity of these molecules. Thus, the production of tailor-made oligo- and polysaccharidic structures by biocatalysis is also a growing field of interest in biotechnology.

  4. Plasma deposition of tungsten

    SciTech Connect

    Greenberg, K.E.

    1986-12-01

    Tungsten films were plasma-deposited using an abnormal glow discharge through a mixture of tungsten hexafluoride, hydrogen, and argon. The films adhered well to silicon, silicon dioxide, gallium arsenide, and aluminum substrates placed directly on the discharge cathode. Typical deposition rates were on the order of 160 Angstroms/minute with as-deposited film resistivities of 40 to 70 microohm-cm. The tungsten was analyzed using a number of techniques including x-ray diffraction, scanning electron microscopy, and Auger spectroscopy. Low-resistivity (<10 microohm-cm) films that adhered well to silicon dioxide were obtained with a two-step process utilizing plasma deposition and conventional chemical vapor deposition.

  5. Dynamic properties of biologically active synthetic heparin-like hexasaccharides.

    PubMed

    Angulo, Jesús; Hricovíni, Milos; Gairi, Margarida; Guerrini, Marco; de Paz, José Luis; Ojeda, Rafael; Martín-Lomas, Manuel; Nieto, Pedro M

    2005-10-01

    A complete study of the dynamics of two synthetic heparin-like hexasaccharides, D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-(1-->4)-L-IdoA-2-SO4-alpha-1-->iPr (1) and -->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHAc-6-SO4-alpha-(1-->4)-L-IdoA-alpha-(1-->4)-D-GlcNHSO3-alpha-(1-->4)-L-IdoA-2-SO4-alpha-1-->iPr (2), has been performed using 13C-nuclear magnetic resonance (NMR) relaxation parameters, T1, T2, and heteronuclear nuclear Overhauser effect (NOEs). Compound 1 is constituted from sequences corresponding to the major polysaccharide heparin region, while compound 2 contains a sequence never found in natural heparin. They differ from each other only in sulphation patterns, and are capable of stimulating fibroblast growth factors (FGFs)-1 induced mitogenesis. Both oligosaccharides exhibit a remarkable anisotropic overall motion in solution as revealed by their anisotropic ratios (tau /tau||), 4.0 and 3.0 respectively. This is a characteristic behaviour of natural glycosaminoglycans (GAG) which has also been observed for the antithrombin (AT) binding pentasaccharide D-GlcNHSO3-6-SO4-alpha-(1-->4)-D-GlcA-beta-(1-->4)-D-GlcNHSO3-(3,6-SO4)-alpha-(1-->4)-L-IdoA-2-SO4-alpha-(1-->4)-D-GlcNHSO3-6-SO4-alpha-1-->Me (3) (Hricovíni, M., Guerrini, M., Torri, G., Piani, S., and Ungarelli, F. (1995) Conformational analysis of heparin epoxide in aqueous solution. An NMR relaxation study. Carbohydr. Res., 277, 11-23). The motional properties observed for 1 and 2 provide additional support to the suitability of these compounds as heparin models in agreement with previous structural (de Paz, J.L., Angulo, J., Lassaletta, J.M., Nieto, P.M., Redondo-Horcajo, M., Lozano, R.M., Jiménez-Gallego, G., and Martín-Lomas, M. (2001) The activation of fibroblast growth factors by heparin: synthesis, structure and biological activity of heparin-like oligosaccharides. Chembiochem, 2, 673-685; Ojeda, R

  6. [Endogenous heparin-like syndrome: analysis of clinical observations].

    PubMed

    Bulanov, A Iu; Iatskov, K V; Shulutko, E M; Glukhova, T E; Andreĭchenko, S A

    2012-01-01

    One of the reasons for non-surgical bleeding is heparin-like syndrome (HLS), under which is understanded presence of heparin effect in the absence of it's exogenous application. The role of endogenous heparins perform glycosaminoglycans -- biologically active substances. HLS is accompanied by endothelium damage and discussed in the network of the systemic inflammatory response syndrome (SIRS). HLS is described in liver future, sepsis, pregnancy and a number of hemoblastosis. Hypocoagulation effect of endogenous heparin localizates in X coagulation factor. The main method of diagnosis - thromboelastography. The use of a specific heparin antidote - Protamine sulfate has not confirmed clinical efficacy. Priority direction in the therapy of - methods of "shunt hemostasis". In this paper, we present the analysis of observations of 4 patients with developed endogenous HLS. In 2 cases (combination of sepsis with hepatic failure in one patient and initial thrombophilia in other) HLS has been accompanied by massive bleeding (massive hemothoraxc with haemorrhagic shock, a massive intraoperative blood loss). For HLS relief in these cases was used prothrombine complex concentrate (PCC) (in the 1st case), recombinant VIIa factor (in the 2nd case). In other cases, HLS (in a patient with multiple myeloma and childbirth in the postpartum period), haemorrhagic syndrome was not so expressed, the treatment was carried out with FFP transfusion.

  7. Synthesis of heparin-like oligosaccharides on polymer supports.

    PubMed

    Ojeda, Rafael; Terentí, Olimpia; de Paz, José-Luis; Martín-Lomas, Manuel

    2004-01-01

    The biological functions of a variety of proteins are regulated by heparan sulfate glycosaminoglycans. In order to facilitate the elucidation of the molecular basis of glycosaminoglycan-protein interactions we have developed syntheses of heparin-like oligosaccharides on polymer supports. A completely stereoselective strategy previously developed by us for the synthesis of these oligosaccharides in solution has been extended to the solid phase using an acceptor-bound approach. Both a soluble polymer support and a polyethylene glycol-grafted polystyrene resin have been used and different strategies for the attachment of the acceptor to the support have been explored. The attachment of fully protected disaccharide building blocks to a soluble support through the carboxylic group of the uronic acid unit by a succinic ester linkage, the use of trichloroacetimidates as glycosylating agents and of a functionalized Merryfield type resin for the capping process allowed for the construction of hexasaccharide and octasaccharide fragments containing the structural motif of the regular region of heparin. This strategy may facilitate the synthesis of glycosaminoglycan oligosaccharides by using the required building blocks in the glycosylation sequence.

  8. Synthesis and structural study of two new heparin-like hexasaccharides.

    PubMed

    Lucas, Ricardo; Angulo, Jesús; Nieto, Pedro M; Martín-Lomas, Manuel

    2003-07-07

    Two new heparin-like hexasaccharides, 5 and 6, have been synthesised using a convergent block strategy and their solution conformations have been determined by NMR spectroscopy and molecular modelling. Both hexasaccharides contain the basic structural motif of the regular region of heparin but with negative charge distributions which have been designed to get insight into the mechanism of fibroblast growth factors (FGFs) activation.

  9. Liquid injection plasma deposition method and apparatus

    DOEpatents

    Kong, P.C.; Watkins, A.D.

    1999-05-25

    A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube. 8 figs.

  10. Liquid injection plasma deposition method and apparatus

    DOEpatents

    Kong, Peter C.; Watkins, Arthur D.

    1999-01-01

    A liquid injection plasma torch deposition apparatus for depositing material onto a surface of a substrate may comprise a plasma torch for producing a jet of plasma from an outlet nozzle. A plasma confinement tube having an inlet end and an outlet end and a central bore therethrough is aligned with the outlet nozzle of the plasma torch so that the plasma jet is directed into the inlet end of the plasma confinement tube and emerges from the outlet end of the plasma confinement tube. The plasma confinement tube also includes an injection port transverse to the central bore. A liquid injection device connected to the injection port of the plasma confinement tube injects a liquid reactant mixture containing the material to be deposited onto the surface of the substrate through the injection port and into the central bore of the plasma confinement tube.

  11. Plasma deposited rider rings for hot displacer

    DOEpatents

    Kroebig, Helmut L.

    1976-01-01

    A hot cylinder for a cryogenic refrigerator having two plasma spray deposited rider rings of a corrosion and abrasion resistant material provided in the rider ring grooves, wherein the rider rings are machined to the desired diameter and width after deposition. The rider rings have gas flow flats machined on their outer surface.

  12. On coating adhesion during impulse plasma deposition

    NASA Astrophysics Data System (ADS)

    Nowakowska-Langier, Katarzyna; Zdunek, Krzysztof; Chodun, Rafal; Okrasa, Sebastian; Kwiatkowski, Roch; Malinowski, Karol; Składnik-Sadowska, Elzbieta; Sadowski, Marek J.

    2014-05-01

    The impulse plasma deposition (IPD) technique is the only method of plasma surface engineering (among plasma-based technologies) that allows a synthesis of layers upon a cold unheated substrate and which ensures a good adhesion. This paper presents a study of plasma impacts upon a copper substrate surface during the IPD process. The substrate was exposed to pulsed N2/Al plasma streams during the synthesis of AlN layers. For plasma-material interaction diagnostics, the optical emission spectroscopy method was used. Our results show that interactions of plasma lead to sputtering of the substrate material. It seems that the obtained adhesion of the layers is the result of a complex surface mechanism combined with the effects of pulsed plasma energy impacts upon the unheated substrate. An example of such a result is the value of the critical load for the Al2O3 layer, which was measured by the scratch-test method to be above 40 N.

  13. Monitoring particle growth in deposition plasmas

    NASA Astrophysics Data System (ADS)

    Schlebrowski, T.; Bahre, H.; Böke, M.; Winter, J.

    2013-12-01

    Plasma-enhanced chemical vapor deposition methods are frequently used to deposit barrier layers, e.g. on polymers for food packaging. These plasmas may suffer from particle (dust) formation. We report on a flexible monitoring system for dust. It is based on scanning a 3D plasma volume for particles by laser light scattering. The lower size limit of particles detected in the presented system is 20 nm. We report on existence diagrams for obtaining dust free or dust loaded capacitively or inductively coupled rf-plasmas in C2H2 depending on pressure, flow and rf-power. We further present growth rates for dust in these plasmas and show that monodisperse particles are only obtained during the first growth cycle.

  14. Plasma forces on deposited particles

    NASA Astrophysics Data System (ADS)

    Heijmans, Lucas; Nijdam, Sander

    2016-09-01

    A plasma can have many effects on a substrate. In this contribution we focus on its effects on micrometer sized particles on the substrate. We are especially interested in forces acting on these particles. These have been suggested to be responsible for the lunar glow observed by the Apollo mission astronauts. They have recently also attracted interest as a possible cleaning mechanism for the high-tech industry. We will present experimental measurements of the forces acting on a particle on a substrate under influence of a plasma. To this extend we have developed two specialised experimental setups. They use extreme accelerations (up to one million times the earth gravitational acceleration) to balance forces on the particle. We will show quantitative measurements of the plasma force effects, and show what underlying physical effects cause them.

  15. Plasma distribution of cathodic ARC deposition system

    SciTech Connect

    Anders, S.; Raoux, S.; Krishnan, K.; MacGill, R.A.; Brown, I.G.

    1996-08-01

    The plasma distribution using a cathodic arc plasma source with and without magnetic macroparticle filter has been determined by depositing on a transparent plastic substrate and measuring the film absorption. It was found that the width of the distribution depends on the arc current, and it also depends on the cathode material which leads to a spatial separation of the elements when an alloy cathode is used. By applying a magnetic multicusp field near the exit of the magnetic filter, it was possible to modify the plasma distribution and obtain a flat plasma profile with a constant and homogeneous elemental distribution.

  16. Plasma deposition of amorphous metal alloys

    DOEpatents

    Hays, A.K.

    1979-07-18

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  17. Plasma deposition of amorphous metal alloys

    DOEpatents

    Hays, Auda K.

    1986-01-01

    Amorphous metal alloy coatings are plasma-deposited by dissociation of vapors of organometallic compounds and metalloid hydrides in the presence of a reducing gas, using a glow discharge. Tetracarbonylnickel, phosphine, and hydrogen constitute a typical reaction mixture of the invention, yielding a NiPC alloy.

  18. Diagnostics in ? helicon plasmas for ? deposition

    NASA Astrophysics Data System (ADS)

    Granier, A.; Nicolazo, F.; Vallée, C.; Goullet, A.; Turban, G.; Grolleau, B.

    1997-05-01

    0963-0252/6/2/008/img3 and 0963-0252/6/2/008/img4 helicon plasmas used for plasma enhanced chemical vapour deposition of 0963-0252/6/2/008/img5 films are investigated in the 1 - 10 mTorr pressure and 0 - 800 W rf power ranges. The positive oxygen ions are analysed by energy selective mass spectrometry and Langmuir probes. The oxygen atom concentration is monitored by actinometry and ionization threshold mass spectrometry. In oxygen plasmas it is shown that 0963-0252/6/2/008/img6 is the major positive ion, and that the oxygen molecules are far from being completely dissociated, due to a very high oxygen atom recombination frequency on the reactor walls. The dissociation degree increases with the rf power reaching 10% at 500 W. In 0963-0252/6/2/008/img4 plasmas, the plasma density and electron temperature decrease as the TEOS fraction increases. In contrast, the degree of oxygen dissociation increases sharply with the addition of a few per cent TEOS, is maximum for about 5% TEOS and decreases as TEOS fraction is further increased. In a 95:5 0963-0252/6/2/008/img4 plasma (5 mTorr, 300 W) the fluxes of oxygen positive ions and atoms impinging onto a floating substrate are estimated to be 0963-0252/6/2/008/img9 and 0963-0252/6/2/008/img10 respectively. Under these plasma conditions, near-stoichiometric 0963-0252/6/2/008/img11 films, with low OH content, are deposited at ambient temperature. The corresponding atom to ion flux ratio is about 250, which suggests the dominant role of oxygen atoms in the deposition kinetics. The comparison of the compositions of layers grown in a 5 mTorr 95:5 0963-0252/6/2/008/img4 plasma at two rf powers confirms the major role of oxygen atoms.

  19. Plasma transferred arc deposition of beryllium

    NASA Astrophysics Data System (ADS)

    Hollis, K.; Bartram, B.; Withers, J.; Storm, R.; Massarello, J.

    2006-12-01

    The exceptional properties of beryllium (Be), including low density and high elastic modulus, make it the material of choice in many defense and aerospace applications. However, health hazards associated with Be material handling limit the applications that are suited for its use. Innovative solutions that enable continued use of Be in critical applications while addressing worker health concerns are highly desirable. Plasma transferred arc solid free-form fabrication is being evaluated as a Be fabrication technique for civilian and military space-based components. Initial experiments producing Be deposits are reported here. Deposit shape, microstructure, and mechanical properties are reported.

  20. [Electron cyclotron resonance (ECR) plasma film deposition

    SciTech Connect

    1999-04-01

    During the third quarter of 1995, an electron cyclotron resonance (ECR) plasma film deposition facility was constructed at the University of New Mexico. This work was conducted in support of the Los Alamos/Tycom CRADA agreement to pursue methods of improving drill bit lifetime. Work in the fourth quarter will center on the coating of drill bits and the treating and testing of various test samples. New material systems as well as treatment techniques will be attempted during this period. The following is a brief description of the various subsystems of the film deposition facility. Particular emphasis is placed on the slotted waveguide system as requested.

  1. Plasma-Modified Atomic Layer Deposition

    NASA Astrophysics Data System (ADS)

    Larrabee, Thomas; Prokes, Sharka

    2015-09-01

    PEALD is known to grow thin films with differing properties from those grown purely via chemical reactions, or thermal ALD processes. However, material properties are still limited when compared to films grown by other deposition techniques. We have used non-growth plasma steps in each ALD cycle to modify properties, in a technique we refer to as plasma-modified ALD. To study how non-growth plasma steps modify properties, we have grown metal oxides with various plasma processing steps from CCPs of Ar, O2, N2, and H2 gases at relatively high pressures of 1-2 mbar. A grid is used to screen ion bombardment of the samples within a commercial Beneq TFS-200 reactor, making this plasma configuration indirect, but not remote. Several properties show significant differences between the films grown with and without these additional steps. These altered properties include crystalline orientation as indicated by XRD, plasmon resonances, photoluminescence, electron paramagnetic resonance, optical dispersion, mobilities, carrier concentrations, and resistivities. Selected plasma-initiated modifications to ALD-grown oxides of zinc, vanadium, and hafnium, and their anticipated applications in novel materials systems will be presented. NRC Postdoc at the Naval Research Laboratory.

  2. Effects of Ar plasma treatment for deposition of ruthenium film by remote plasma atomic layer deposition

    SciTech Connect

    Park, Taeyong; Lee, Jaesang; Park, Jingyu; Jeon, Heeyoung; Jeon, Hyeongtag; Lee, Ki-Hoon; Cho, Byung-Chul; Kim, Moo-Sung; Ahn, Heui-Bok

    2012-01-15

    Ruthenium thin films were deposited on argon plasma-treated SiO{sub 2} and untreated SiO{sub 2} substrates by remote plasma atomic layer deposition using bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp){sub 2}] as a Ru precursor and ammonia plasma as a reactant. The results of in situ Auger electron spectroscopy (AES) analysis indicate that the initial transient region of Ru deposition was decreased by Ar plasma treatment at 400 deg. C, but did not change significantly at 300 deg. C The deposition rate exhibited linearity after continuous film formation and the deposition rates were about 1.7 A/cycle and 0.4 A/cycle at 400 deg. C and 300 deg. C, respectively. Changes of surface energy and polar and dispersive components were measured by the sessile drop test. The quantity of surface amine groups was measured from the surface nitrogen concentration with AES. Furthermore, the Ar plasma-treated SiO{sub 2} contained more amine groups and less hydroxyl groups on the surface than on untreated SiO{sub 2}. Auger spectra exhibited chemical shifts by Ru-O bonding, and larger shifts were observed on untreated substrates due to the strong adhesion of Ru films.

  3. Tungsten Deposition on Graphite using Plasma Enhanced Chemical Vapour Deposition.

    NASA Astrophysics Data System (ADS)

    Sharma, Uttam; Chauhan, Sachin S.; Sharma, Jayshree; Sanyasi, A. K.; Ghosh, J.; Choudhary, K. K.; Ghosh, S. K.

    2016-10-01

    The tokamak concept is the frontrunner for achieving controlled thermonuclear reaction on earth, an environment friendly way to solve future energy crisis. Although much progress has been made in controlling the heated fusion plasmas (temperature ∼ 150 million degrees) in tokamaks, technological issues related to plasma wall interaction topic still need focused attention. In future, reactor grade tokamak operational scenarios, the reactor wall and target plates are expected to experience a heat load of 10 MW/m2 and even more during the unfortunate events of ELM's and disruptions. Tungsten remains a suitable choice for the wall and target plates. It can withstand high temperatures, its ductile to brittle temperature is fairly low and it has low sputtering yield and low fuel retention capabilities. However, it is difficult to machine tungsten and hence usages of tungsten coated surfaces are mostly desirable. To produce tungsten coated graphite tiles for the above-mentioned purpose, a coating reactor has been designed, developed and made operational at the SVITS, Indore. Tungsten coating on graphite has been attempted and successfully carried out by using radio frequency induced plasma enhanced chemical vapour deposition (rf -PECVD) for the first time in India. Tungsten hexa-fluoride has been used as a pre-cursor gas. Energy Dispersive X-ray spectroscopy (EDS) clearly showed the presence of tungsten coating on the graphite samples. This paper presents the details of successful operation and achievement of tungsten coating in the reactor at SVITS.

  4. Plasma-enhanced chemical vapor deposition of tungsten films

    NASA Astrophysics Data System (ADS)

    Chu, J. K.; Tang, C. C.; Hess, D. W.

    1982-07-01

    High-purity films of tungsten are deposited from tungsten hexafluoride and hydrogen using plasma-enhanced deposition (PED). At 400 °C deposition temperature, resistivities of ˜40 μΩ cm are attained. After annealing at 1100 °C, the resistivity falls to ˜7 μΩ cm. Below 400 °C, the as-deposited film stress is <6×109 dynes/cm2. Tensile, unlike tungsten, molybdenum films deposited by PED displayed high resistivities.

  5. Plasma polymerized acetylene deposition using a return corona enhanced plasma reactor

    NASA Astrophysics Data System (ADS)

    Islam, Rokibul; Xie, Shuzheng; Englund, Karl R.; Pedrow, Patrick D.

    2017-08-01

    A corona based weakly ionized plasma source was developed to deposit plasma polymerized acetylene coating at atmospheric pressure. The plasma source included a distinctive point-to-point geometry consisting of an array of high voltage needles and an array of protrusions placed over a grounded screen. The geometry facilitated various corona discharge modes that included return corona to contribute plasma polymerized acetylene deposition downstream from the corona section. Scanning probe techniques were used to investigate deposition on both the leading surface and the trailing surface of substrates. Deposition was initiated as distinct nodules that merged to form a thin plasma polymerized coating.

  6. Deposition of diamond-like films by ECR microwave plasma

    NASA Technical Reports Server (NTRS)

    Shing, Yuh-Han (Inventor); Pool, Frederick S. (Inventor)

    1995-01-01

    Hard amorphous hydrogenated carbon, diamond-like films are deposited using an electron cyclotron resonance microwave plasma with a separate radio frequency power bias applied to a substrate stage. The electron cyclotron resonance microwave plasma yields low deposition pressure and creates ion species otherwise unavailable. A magnetic mirror configuration extracts special ion species from a plasma chamber. Different levels of the radio frequency power bias accelerate the ion species of the ECR plasma impinging on a substrate to form different diamond-like films. During the deposition process, a sample stage is maintained at an ambient temperature of less than 100.degree. C. No external heating is applied to the sample stage. The deposition process enables diamond-like films to be deposited on heat-sensitive substrates.

  7. Plasma reactor for deposition of carbon nanowalls at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Dimitrov, Zh; Mitev, D.; Kiss'ovski, Zh

    2016-10-01

    In this study a novel plasma reactor for deposition of carbon nanowalls at atmospheric pressure is constructed and characterized. A low power microwave discharge is used as a plasma source and working gas of Ar/H2/CH4 gas mixture. The substrate is heated by plasma flame and its temperature is in the range 600-700 C. The chemical composition of the plasma and the gas mixture effect on the concentration of the various particles in the plasma is investigated by optical emission spectroscopy. The emission spectrum of the plasma jet in Ar/H2/CH4 mixture shows the presence of carbon (Swan band) and an intensive line of CH (388 nm), which are necessary species for deposition of carbon nanostructures. Additional voltage in the range from -20 V to -100 V is applied in order to ensure the vertical growth of graphene walls. Results of deposited carbon nanostructures on metal substrate are shown.

  8. Plasma sprayed and electrospark deposited zirconium metal diffusion barrier coatings

    SciTech Connect

    Hollis, Kendall J; Pena, Maria I

    2010-01-01

    Zirconium metal coatings applied by plasma spraying and electrospark deposition (ESD) have been investigated for use as diffusion barrier coatings on low enrichment uranium fuel for research nuclear reactors. The coatings have been applied to both stainless steel as a surrogate and to simulated nuclear fuel uranium-molybdenum alloy substrates. Deposition parameter development accompanied by coating characterization has been performed. The structure of the plasma sprayed coating was shown to vary with transferred arc current during deposition. The structure of ESD coatings was shown to vary with the capacitance of the deposition equipment.

  9. Modified drug release using atmospheric pressure plasma deposited siloxane coatings

    NASA Astrophysics Data System (ADS)

    Dowling, D. P.; Maher, S.; Law, V. J.; Ardhaoui, M.; Stallard, C.; Keenan, A.

    2016-09-01

    This pilot study evaluates the potential of atmospheric plasma polymerised coatings to modify the rate of drug release from polymeric substrates. The antibiotic rifampicin was deposited in a prototype multi-layer drug delivery system, consisting of a nebulized layer of active drug between a base layer of TEOS deposited on a plastic substrate (polystyrene) and an overlying layer of plasma polymerised PDMS. The polymerised TEOS and PDMS layers were deposited using a helium atmospheric plasma jet system. Elution of rifampicin was measured using UV-VIS spectroscopy, in addition to a antimicrobial well diffusion assay with an established indicator organism. The multi-layered plasma deposited coatings significantly extended the duration of release of the rifampicin from 24 h for the uncoated polymer to 144 h for the coated polymer.

  10. Plasma assisted deposition of metal fluorides for 193nm applications

    NASA Astrophysics Data System (ADS)

    Bischoff, Martin; Sode, Maik; Gaebler, Dieter; Kaiser, Norbert; Tuennermann, Andreas

    2008-10-01

    The ArF lithography technology requires a minimization of optical losses due to scattering and absorption. Consequently it is necessary to optimize the coating process of metal fluorides. The properties of metal fluoride thin films are mainly affected by the deposition methods, their parameters, and the vacuum conditions. Until now the best results were achieved by metal boat evaporation with high substrate temperature and without plasma assistance. In fact, it was demonstrated that the plasma assisted deposition process results in optical thin films with high packing density but the losses due to absorption were extremely high for deep and vacuum ultraviolet applications. This paper will demonstrate that most of the common metal fluorides can be deposited by electron beam evaporation with plasma assistance. In comparison to other deposition methods, the prepared thin films show low absorption in the VUV spectral range, high packing density, and less water content. The densification of the thin films was performed by a Leybold LION plasma source. As working gas, a variable mixture of fluorine and argon gas was chosen. To understand the deposition process and the interaction of the plasma with the deposition material, various characterization methods like plasma emission spectroscopy and ion current measurements were implemented.

  11. Electroless metallization onto pulsed plasma deposited poly(4-vinylpyridine) surfaces.

    PubMed

    Bradley, T J; Schofield, W C E; Garrod, R P; Badyal, J P S

    2006-08-29

    Pulsed plasma-chemical deposition of poly(4-vinylpyridine) is found to be a highly effective way of functionalizing solid surfaces with pyridine ring centers. These surfaces can be metallized via complexation to Pd2+ ions from solution, followed by autocatalytic electroless deposition of either copper or nickel films.

  12. A study of reactive plasma deposited thin films

    NASA Technical Reports Server (NTRS)

    Gilchrist, J.; Williams, E.

    1986-01-01

    A state-of-the-art research laboratory was established to grow and characterize amorphous thin films that are useful in semi-conductor devices. Two film systems, nitride films and silicon dioxide films were studied. Over seventy deposition runs for nitride films were made. The films were deposited on silicon substrate using plasma enhanced chemical vapor deposition. It was found that the uniformity of the films were affected by the location of the film on the platen.

  13. Vapor Phase Deposition Using Plasma Spray-PVD™

    NASA Astrophysics Data System (ADS)

    von Niessen, K.; Gindrat, M.; Refke, A.

    2010-01-01

    Plasma spray—physical vapor deposition (PS-PVD) is a low pressure plasma spray technology to deposit coatings out of the vapor phase. PS-PVD is a part of the family of new hybrid processes recently developed by Sulzer Metco AG (Switzerland) on the basis of the well-established low pressure plasma spraying (LPPS) technology. Included in this new process family are plasma spray—chemical vapor deposition (PS-CVD) and plasma spray—thin film (PS-TF) processes. In comparison to conventional vacuum plasma spraying and LPPS, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and EB-PVD coatings. This paper reports on the progress made at Sulzer Metco to develop functional coatings build up from vapor phase of oxide ceramics and metals.

  14. Reactive deposition of tungsten and titanium carbides by induction plasma

    NASA Astrophysics Data System (ADS)

    Jiang, X. L.; Gitzhofer, F.; Boulos, M. I.; Tiwari, R.

    1995-05-01

    A study is reported on the use of induction plasma technology for the preparation of dense free-standing deposits of tungsten carbide and titanium carbide from metallic powders and methane. Phase analysis by X-ray diffraction indicates that primary carburization of the particles takes place in-flight giving rise to the formation of W2C and TiC(1 - x). Secondary carburization occurs in the deposits resulting in the formation of tungsten and titanium carbides. Microstructures revealed by optical and scanning electron microscopy show uniform small grains of the carbides. The reactive plasma spray-formed tungsten carbide shows transgranular fracture, while pure tungsten deposits show intergranular fracture.

  15. Staphylococcus epidermidis adhesion to films deposited from hydroxyethylmethacrylate plasma.

    PubMed

    Morra, M; Cassinelli, C

    1996-06-01

    The adhesion of S. epidermidis ATCC 35984 strain on polystyrene (PS) disks coated by films deposited from hydroxyethylmethacrylate (HEMA) plasma was evaluated and compared to adhesion on untreated PS and oxygen-plasma-treated PS. Films were deposited keeping constant the monomer flow rate while the discharge power ranged from 40-100 W in order to obtain coating with different surface properties. Surface chemistry, energetics, and morphology were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA), contact angle measurement, and Atomic Force Microscopy (AFM), respectively. Bacteria adhered more to the plasma-deposited or plasma-treated surfaces than to untreated PS, but no significant difference was recorded among the samples obtained using different deposition conditions. According to the surface energetic analysis, plasma-deposited and plasma-treated surfaces bear a strong Lewis-base character, so it is possible to hypothesize a marked contribution of electron donor-electron acceptor interactions to the mechanism(s) controlling adhesion between synthetic and bacterial surfaces.

  16. Plasma enhanced atomic layer deposition of silicon nitride using neopentasilane

    SciTech Connect

    Weeks, Stephen Nowling, Greg; Fuchigami, Nobi; Bowes, Michael; Littau, Karl

    2016-01-15

    Progress in transistor scaling has increased the demands on the material properties of silicon nitride (SiN{sub x}) thin films used in device fabrication and at the same time placed stringent restrictions on the deposition conditions employed. Recently, low temperature plasma enhanced atomic layer deposition has emerged as a viable technique for depositing these films with a thermal budget compatible with semiconductor processing at sub-32 nm technology nodes. For these depositions, it is desirable to use precursors that are free from carbon and halogens that can incorporate into the film. Beyond this, it is necessary to develop processing schemes that minimize the wet etch rate of the film as it will be subjected to wet chemical processing in subsequent fabrication steps. In this work, the authors introduce low temperature deposition of SiN{sub x} using neopentasilane [NPS, (SiH{sub 3}){sub 4}Si] in a plasma enhanced atomic layer deposition process with a direct N{sub 2} plasma. The growth with NPS is compared to a more common precursor, trisilylamine [TSA, (SiH{sub 3}){sub 3 }N] at identical process conditions. The wet etch rates of the films deposited with NPS are characterized at different plasma conditions and the impact of ion energy is discussed.

  17. Diamond film deposition using microwave plasmas under low pressures

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.; Rich, D. H.

    1991-01-01

    Microwave plasma depositions of diamond films have been investigated under low pressures of 10 mTorr to 10 Torr, at low substrate temperatures of 400 to 750 C, using high methane concentrations of 5 to 15 percent and oxygen concentrations of 5 to 10 percent in hydrogen plasmas. The deposition system consists of a microwave plasma chamber, a downstream deposition chamber, and a RF induction-heated sample stage. The deposition system can be operated in either high-pressure microwave or electron cyclotron resonance (ECR) modes by varying the sample stage position. Cathodoluminescence (CL) studies on diamond films deposited at 10 Torr pressure show that CL emissions at 430, 480, 510, 530, 560, 570 and 740 nm can be employed to characterize the quality of diamond films. High-quality, well-faceted diamond films have been deposited at 10 Torr and 600 C using 5 percent CH4 and 5 percent O2 in H2 plasmas; CL measurements on these films show very low N impurities and no detectable Si impurities. Diamond nucleation on SiC has been demonstrated by depositing well-faceted diamond crystallites on SiC-coated Si substrates.

  18. Diamond film deposition using microwave plasmas under low pressures

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.; Rich, D. H.

    1991-01-01

    Microwave plasma depositions of diamond films have been investigated under low pressures of 10 mTorr to 10 Torr, at low substrate temperatures of 400 to 750 C, using high methane concentrations of 5 to 15 percent and oxygen concentrations of 5 to 10 percent in hydrogen plasmas. The deposition system consists of a microwave plasma chamber, a downstream deposition chamber, and a RF induction-heated sample stage. The deposition system can be operated in either high-pressure microwave or electron cyclotron resonance (ECR) modes by varying the sample stage position. Cathodoluminescence (CL) studies on diamond films deposited at 10 Torr pressure show that CL emissions at 430, 480, 510, 530, 560, 570 and 740 nm can be employed to characterize the quality of diamond films. High-quality, well-faceted diamond films have been deposited at 10 Torr and 600 C using 5 percent CH4 and 5 percent O2 in H2 plasmas; CL measurements on these films show very low N impurities and no detectable Si impurities. Diamond nucleation on SiC has been demonstrated by depositing well-faceted diamond crystallites on SiC-coated Si substrates.

  19. Nanoparticle formation and thin film deposition in aniline containing plasmas

    NASA Astrophysics Data System (ADS)

    Pattyn, Cedric; Dias, Ana; Hussain, Shahzad; Strunskus, Thomas; Stefanovic, Ilija; Boulmer-Leborgne, Chantal; Lecas, Thomas; Kovacevic, Eva; Berndt, Johannes

    2016-09-01

    This contribution deals with plasma based polymerization processes in mixtures of argon and aniline. The investigations are performed in a capacitively coupled RF discharge (in pulsed and continuous mode) and concern both the observed formation of nanoparticles in the plasma volume and the deposition of films. The latter process was used for the deposition of ultra-thin layers on different kind of nanocarbon materials (nanotubes and free standing graphene). The analysis of the plasma and the plasma chemistry (by means of mass spectroscopy and in-situ FTIR spectroscopy) is accompanied by several ex-situ diagnostics of the obtained materials which include NEXAFS and XPS measurements as well as Raman spectroscopy and electron microscopy. The decisive point of the investigations concern the preservation of the original monomer structure during the plasma polymerization processes and the stability of the thin films on the different substrates.

  20. Deposition of electrochromic tungsten oxide thin films by plasma-enhanced chemical vapor deposition

    SciTech Connect

    Henley, W.B.; Sacks, G.J.

    1997-03-01

    Use of plasma-enhanced chemical vapor deposition (PECVD) for electrochromic WO{sub 3} film deposition is investigated. Oxygen, hydrogen, and tungsten hexafluoride were used as source gases. Reactant gas flow was investigated to determine the effect on film characteristics. High quality optical films were obtained at deposition rates on the order of 100 {angstrom}/s. Higher deposition rates were attainable but film quality and optical coherence degraded. Atomic emission spectroscopy (AES), was used to provide an in situ assessment of the plasma deposition chemistry. Through AES, it is shown that the hydrogen gas flow is essential to the deposition of the WO{sub 3} film. Oxygen gas flow and tungsten hexafluoride gas flow must be approximately equal for high quality films.

  1. Film synthesis on powders by cathodic arc plasma deposition

    SciTech Connect

    Anders, A.; Anders, S.; Brown, I.G.; Ivanov, I.C.

    1995-04-01

    Cathodic arc plasma deposition was used to coat Al{sub 2}O{sub 3} powder (mesh size 60) with platinum. The power particles were moved during deposition using a mechanical system operating at a resonance frequency of 20 Hz. Scanning electron microscopy and Auger electron microscopy show that all particles are completely coated with a platinum film having a thickness of about 100 nm. The actual deposition time was only 20 s, thus the deposition rate was very high (5 nm/s).

  2. A multifunctional plasma and deposition sensor for the characterization of plasma sources for film deposition and etching

    NASA Astrophysics Data System (ADS)

    Weise, Michael; Seeger, Stefan; Harbauer, Karsten; Welzel, Thomas; Ellmer, Klaus

    2017-07-01

    Our recently reported multifunctional plasma and deposition sensor [Welzel et al., Appl. Phys. Lett. 102, 211605 (2013)] was used for the characterization of two different plasma sources: a magnetron sputtering deposition source and an ion beam source. The multifunctional sensor, based on a conventional quartz crystal monitor (microbalance) for mass increase/decrease measurements, can measure quasi-simultaneously the deposition/etching flux, the energy flux, and the charged particle flux. By moving the sensor or the plasma source stepwise against each other, the lateral (radial) flux profiles of the different sources can be measured with a lateral resolution of about 8 mm, the diameter of aperture in front of the quartz crystal. It is demonstrated that this compact and simple multifunctional sensor is a versatile tool for the characterization of different kinds of plasma sources for deposition and etching purposes. By combining the different measured quantities, the ion-to-neutral ratio and the mean energy per deposited atom can be calculated, parameters that are essential for the characterization of plasma deposition and etch processes.

  3. A high temperature, plasma-assisted chemical vapor deposition system

    SciTech Connect

    Brusasco, R.M.; Britten, J.A.; Thorsness, C.B.; Scrivener, M.S.; Unites, W.G.; Campbell, J.H. ); Johnson, W.L. )

    1990-02-01

    We have designed and built a high-temperature, plasma-assisted, chemical vapor deposition system to deposit multilayer optical coatings of SiO{sub 2} and doped-SiO{sub 2} flat substrates. The coater concept and design is an outgrowth of our recent work with Schott Glasswerke demonstrating the use of plasma assisted CVD to prepare very high damage threshold optical coatings. The coater is designed to deposit up to several thousand alternating quarterwave layers of SiO{sub 2} and doped SiO{sub 2} substrate at deposition rates up to several microns per minute. The substrate is resistively heated to about 1000{degree}C during the deposition phase of the process. The plasma is driven by a 13.56 MHz RF unit capable of producing power densities of up to 140 W cm{sup {minus}3} in the reaction zone. The coater is designed to be adaptable to microwave generated plasmas, as well as RF. Reactant gas flow rates of up to 10 slm can be achieved at a 10 tar operating pressure. Reactants consist of O{sub 2}, SiCl{sub 4} and a volatile halogenated dopant. These gases react in the plasma volume producing SiO{sub 2} with dopant concentrations of up to a few percent. A variable dopant concentration is used to produce index differences between adjacent optical layers.

  4. Solid coatings deposited from liquid methyl methacrylate via Plasma Polymerization

    NASA Astrophysics Data System (ADS)

    Wurlitzer, Lisa; Maus-Friedrichs, Wolfgang; Dahle, Sebastian

    2016-09-01

    The polymerization of methyl methacrylate via plasma discharges is well known today. Usually, plasma-enhanced chemical vapor deposition (PECVD) is used to deposit polymer coatings. Solid coatings are formed out of the liquid phase from methyl methacrylate via dielectric barrier discharge. The formation of the coating proceeds in the gas and the liquid phase. To learn more about the reactions in the two phases, the coatings from MMA monomer will be compared to those from MMA resin. Finally, attenuated total reflection infrared spectroscopy, confocal laser scanning microscopy and X-ray photoelectron spectroscopy are employed to characterize the solid coatings. In conclusion, the plasma enhanced chemical solution deposition is compared to the classical thermal polymerization of MMA.

  5. Plasma deposited silicon nitride for indium phosphide encapsulation

    NASA Technical Reports Server (NTRS)

    Valco, G. J.; Kapoor, V. J.; Biedenbender, M. D.; Williams, W. D.

    1989-01-01

    The composition and the annealing characteristics of plasma-deposited silicon-nitride encapsulating films on the ion-implanted InP substrates were investigated, using two different substrate-cleaning procedures (organic solvents and HF or HIO3 solutions) prior to encapsulation. The effect of plasma deposition of silicon nitride on the InP substrates was assessed through the current-voltage characteristics of Schottky diodes. Results of XPS analyses showed that the cleaning procedure that employed HF solution left less oxygen on the InP surface than the procedure involving HIO3. No chemical interaction between the film and the substrate was observed before or after annealing.

  6. Plasma deposited silicon nitride for indium phosphide encapsulation

    NASA Technical Reports Server (NTRS)

    Valco, G. J.; Kapoor, V. J.; Biedenbender, M. D.; Williams, W. D.

    1989-01-01

    The composition and the annealing characteristics of plasma-deposited silicon-nitride encapsulating films on the ion-implanted InP substrates were investigated, using two different substrate-cleaning procedures (organic solvents and HF or HIO3 solutions) prior to encapsulation. The effect of plasma deposition of silicon nitride on the InP substrates was assessed through the current-voltage characteristics of Schottky diodes. Results of XPS analyses showed that the cleaning procedure that employed HF solution left less oxygen on the InP surface than the procedure involving HIO3. No chemical interaction between the film and the substrate was observed before or after annealing.

  7. Microwave plasma deposition of diamond like carbon coatings

    NASA Astrophysics Data System (ADS)

    Patil, D. S.; Ramachandran, K.; Venkataramani, N.; Pandey, M.; D'Cunha, R.

    2000-11-01

    he promising applications of the microwave plasmas have been appearing in the fields of chemical processes and semiconductor manufacturing. Applications include surface deposition of all types including diamond/diamond like carbon (DLC) coatings, etching of semiconductors, promotion of organic reactions, etching of polymers to improve bonding of the other materials etc. With a 2.45 GHz, 700 W, microwave induced plasma chemical vapor deposition (CVD) system set up in our laboratory we have deposited diamond like carbon coatings. The microwave plasma generation was effected using a wave guide single mode applicator. We have deposited DLC coatings on the substrates like stainless steel, Cu--Be, Cu and Si. The deposited coatings have been characterized by FTIR, Raman spectroscopy and ellipsometric techniques. The results show that we have achieved depositing ~ 95% sp3 bonded carbon in the films. The films are uniform with golden yellow color. The films are found to be excellent insulators. The ellipsometric measurements of optical constant on silicon substrates indicate that the films are transparent above 900 nm.

  8. Oligomeric self-association of basic fibroblast growth factor in the absence of heparin-like glycosaminoglycans.

    PubMed Central

    Davis, J C; Venkataraman, G; Shriver, Z; Raj, P A; Sasisekharan, R

    1999-01-01

    Basic fibroblast growth factor (FGF-2) represents a class of heparin-binding growth factors that are stored in the extracellular matrix attached to heparin-like glycosaminoglycans (HLGAGs). It has been proposed that cell surface HLGAGs have a central role in the biological activity of FGF-2, presumably by inducing dimers or oligomers of FGF-2 and leading to the dimerization or oligomerization of FGF receptor and hence signal transduction. We have previously proposed that FGF-2 possesses a natural tendency to self-associate to form FGF-2 dimers and oligomers; HLGAGs would enhance FGF-2 self-association. Here, through a combination of spectroscopic, chemical cross-linking and spectrometric techniques, we provide direct evidence for the self-association of FGF-2 in the absence of HLGAGs, defying the notion that HLGAGs induce FGF-2 oligomerization. Further, the addition of HLGAGs seems to enhance significantly the FGF-2 oligomerization process without affecting the relative percentages of FGF-2 dimers, trimers or oligomers. FGF-2 self-association is consistent with FGF-2's possessing biological activity both in the presence and in the absence of HLGAGs; this leads us to propose that FGF-2 self-association enables FGF-2 to signal both in the presence and in the absence of HLGAGs. PMID:10417324

  9. The activation of fibroblast growth factors by heparin: synthesis, structure, and biological activity of heparin-like oligosaccharides.

    PubMed

    de Paz, J L; Angulo, J; Lassaletta, J M; Nieto, P M; Redondo-Horcajo, M; Lozano, R M; Giménez-Gallego, G; Martín-Lomas, M

    2001-09-03

    An effective strategy has been designed for the synthesis of oligosaccharides of different sizes structurally related to the regular region of heparin; this is illustrated by the preparation of hexasaccharide 1 and octasaccharide 2. This synthetic strategy provides the oligosaccharide sequence containing a D-glucosamine unit at the nonreducing end that is not available either by enzymatic or chemical degradation of heparin. It may permit, after slight modifications, the preparation of oligosaccharide fragments with different charge distribution as well. NMR spectroscopy and molecular dynamics simulations have shown that the overall structure of 1 in solution is a stable right-hand helix with four residues per turn. Hexasaccharide 1 and, most likely, octasaccharide 2 are, therefore, chemically well-defined structural models of naturally occurring heparin-like oligosaccharides for use in binding and biological activity studies. Both compounds 1 and 2 induce the mitogenic activity of acid fibroblast growth factor (FGF1), with the half-maximum activating concentration of 2 being equivalent to that of heparin. Sedimentation equilibrium analysis with compound 2 suggests that heparin-induced FGF1 dimerization is not an absolute requirement for biological activity.

  10. Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

    2017-01-01

    Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

  11. Plasma-Powder Feedstock Interaction During Plasma Spray-Physical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Hongbo; Zhang, Baopeng

    2017-02-01

    Plasma spray-physical vapor deposition is a new process developed to produce coatings from the vapor phase. To achieve deposition from the vapor phase, the plasma-feedstock interaction inside the plasma torch, i.e., from the powder injection point to the nozzle exit, is critical. In this work, the plasma characteristics and the momentum and heat transfer between the plasma and powder feedstock at different torch input power levels were investigated theoretically to optimize the net plasma torch power, among other important factors such as the plasma gas composition, powder feed rate, and carrier gas. The plasma characteristics were calculated using the CEA2 code, and the plasma-feedstock interaction was studied inside the torch nozzle at low-pressure (20-25 kPa) conditions. A particle dynamics model was introduced to compute the particle velocity, coupled with Xi Chen's drag model for nonevaporating particles. The results show that the energy transferred to the particles and the coating morphology are greatly influenced by the plasma gas characteristics and the particle dynamics inside the nozzle. The heat transfer between the plasma gas and feedstock material increased with the net torch power up to an optimum at 64 kW, at which a maximum of 3.4% of the available plasma energy was absorbed by the feedstock powder. Experimental results using agglomerated 7-8 wt.% yttria-stabilized zirconia (YSZ) powder as feedstock material confirmed the theoretical predictions.

  12. Plasma deposition of polymer composite films incorporating nanocellulose whiskers

    NASA Astrophysics Data System (ADS)

    Samyn, P.; Airoudj, A.; Laborie, M.-P.; Mathew, A. P.; Roucoules, V.

    2011-11-01

    In a trend for sustainable engineering and functionalization of surfaces, we explore the possibilities of gas phase processes to deposit nanocomposite films. From an analysis of pulsed plasma polymerization of maleic anhydride in the presence of nanocellulose whiskers, it seems that thin nanocomposite films can be deposited with various patterns. By specifically modifying plasma parameters such as total power, duty cycle, and monomer gas pressure, the nanocellulose whiskers are either incorporated into a buckled polymer film or single nanocellulose whiskers are deposited on top of a polymeric film. The density of the latter can be controlled by modifying the exact positioning of the substrate in the reactor. The resulting morphologies are evaluated by optical microscopy, AFM, contact angle measurements and ellipsometry.

  13. Characterization of the WC coatings deposited by plasma spraying

    NASA Astrophysics Data System (ADS)

    Benea, M. L.; Benea, L. P.

    2015-06-01

    Tungsten monocarbide (WC) is deposited using a plasma jet on the martensitic noncorrosive steel support (Z12CNDV12), in three different thicknesses.The characteristics of the coatings are determined by: its chemical composition, optical microscopy, RX analysis, tensile adhesion strength, Vickers hardness, the nature and the processing degree of the substrate and the deposition conditions.The method used for determining the behaviour in a corrosive environment of the WC coatings deposited by plasma spraying consists in measuring the electrochemical potential difference between the coating and the substrate, which are immersed in a solution containing NaCl as a corrosive agent. The experimental results are then mathematically processed in order to determine a law and the mechanisms involved.

  14. Plasma deposited diamond-like carbon films for large neutralarrays

    SciTech Connect

    Brown, I.G.; Blakely, E.A.; Bjornstad, K.A.; Galvin, J.E.; Monteiro, O.R.; Sangyuenyongpipat, S.

    2004-07-15

    To understand how large systems of neurons communicate, we need to develop methods for growing patterned networks of large numbers of neurons. We have found that diamond-like carbon thin films formed by energetic deposition from a filtered vacuum arc carbon plasma can serve as ''neuron friendly'' substrates for the growth of large neural arrays. Lithographic masks can be used to form patterns of diamond-like carbon, and regions of selective neuronal attachment can form patterned neural arrays. In the work described here, we used glass microscope slides as substrates on which diamond-like carbon was deposited. PC-12 rat neurons were then cultured on the treated substrates and cell growth monitored. Neuron growth showed excellent contrast, with prolific growth on the treated surfaces and very low growth on the untreated surfaces. Here we describe the vacuum arc plasma deposition technique employed, and summarize results demonstrating that the approach can be used to form large patterns of neurons.

  15. Interpretation of plasma impurity deposition probes. Analytic approximation

    SciTech Connect

    Stangeby, P.C.

    1987-10-01

    Insertion of a probe into the plasma induces a high speed flow of the hydrogenic plasma to the probe which, by friction, accelerates the impurity ions to velocities approaching the hydrogenic ion acoustic speed, i.e., higher than the impurity ion thermal speed. A simple analytic theory based on this effect provides a relation between impurity fluxes to the probe GAMMA/sub imp/ and the undisturbed impurity ion density n/sub imp/, with the hydrogenic temperature and density as input parameters. Probe size also influences the collection process and large probes are found to attract a higher flux density than small probes in the same plasma. The quantity actually measured, c/sub imp/, the impurity atom surface density (m/sup -2/) net-deposited on the probe, is related to GAMMA/sub imp/ and thus to n/sub imp/ by taking into account the partial removal of deposited material caused by sputtering and the redeposition process.

  16. Properties of N-rich Silicon Nitride Film Deposited by Plasma-Enhanced Atomic Layer Deposition

    NASA Astrophysics Data System (ADS)

    Jhang, Pei-Ci; Lu, Chi-Pin; Shieh, Jung-Yu; Yang, Ling-Wu; Yang, Tahone; Chen, Kuang-Chao; Lu, Chih-Yuan

    2017-07-01

    An N-rich silicon nitride film, with a lower refractive index (RI) than the stoichiometric silicon nitride (RI = 2.01), was deposited by alternating the exposure of dichlorosilane (DCS, SiH2Cl2) and that of ammonia (NH3) in a plasma-enhanced atomic layer deposition (PEALD) process. In this process, the plasma ammonia was easily decomposed to reactive radicals by RF power activating so that the N-rich silicon nitride was easily formed by excited ammonia radicals. The growth kinetics of N-rich silicon nitride were examined at various deposition temperatures ranging from 400 °C to 630 °C; the activation energy (Ea) decreased as the deposition temperature decreased below 550 °C. N-rich silicon nitride film with a wide range of values of refractive index (RI) (RI = 1.86-2.00) was obtained by regulating the deposition temperature. At the optimal deposition temperature, the effects of RF power, NH3 flow rate and NH3 flow time were on the characteristics of the N-rich silicon nitride film were evaluated. The results thus reveal that the properties of the N-rich silicon nitride film that was formed by under plasma-enhanced atomic layer deposition (PEALD) are dominated by deposition temperature. In charge trap flash (CTF) study, an N-rich silicon nitride film was applied to MAONOS device as a charge-trapping layer. The films exhibit excellent electron trapping ability and favor a fresh cell data retention performance as the deposition temperature decreased.

  17. Plasma and Ion Assistance in Physical Vapor Deposition: AHistorical Perspective

    SciTech Connect

    Anders, Andre

    2007-02-28

    Deposition of films using plasma or plasma-assist can betraced back surprisingly far, namely to the 18th century for arcs and tothe 19th century for sputtering. However, only since the 1960s thecoatings community considered other processes than evaporation for largescale commercial use. Ion Plating was perhaps the first importantprocess, introducing vapor ionization and substrate bias to generate abeam of ions arriving on the surface of the growing film. Ratherindependently, cathodic arc deposition was established as an energeticcondensation process, first in the former Soviet Union in the 1970s, andin the 1980s in the Western Hemisphere. About a dozen various ion-basedcoating technologies evolved in the last decades, all characterized byspecific plasma or ion generation processes. Gridded and gridless ionsources were taken from space propulsion and applied to thin filmdeposition. Modeling and simulation have helped to make plasma and ionseffects to be reasonably well understood. Yet--due to the complex, oftennon-linear and non-equilibrium nature of plasma and surfaceinteractions--there is still a place for the experience plasma"sourcerer."

  18. Textured (100) yttria-stabilized zirconia thin films deposited by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Holzschuh, H.; Suhr, H.

    1991-07-01

    Thin films of yttria-stabilized zirconia were deposited by plasma-enhanced chemical vapor deposition on quartz Si(100), Si(111), Ni, and the steels V2A and Hastelloy at substrate temperatures (Ts): 673-873 K. The metal beta-diketonates Y (thd)3 and Zr(thd)4 were used as precursors. The fully stabilized fluorite-type cubic structure was obtained over a wide range of yttria contents from 3.5 to 80 mol pct (Ts = 773 K). The quality of the films depended on the match of the thermal expansion coefficients of substrate and deposit.

  19. Basic fibroblast growth factor binds to subendothelial extracellular matrix and is released by heparitinase and heparin-like molecules

    SciTech Connect

    Bashkin, P.; Doctrow, S.; Klagsbrun, M.; Svahn, C.M.; Folkman, J.; Vlodavsky, I. )

    1989-02-21

    Basic fibroblast growth factor (bFGF) exhibits specific binding to the extracellular matrix (ECM) produced by cultured endothelial cells. Binding was saturable as a function both of time and of concentration of {sup 125}I-bFGF. Scatchard analysis of FGF binding revealed the presence of about 1.5 x 10{sup 12} binding sites/mm{sup 2} ECM with an apparent k{sub D} of 610 nM. FGF binds to heparan sulfate (HS) in ECM as evidenced by (i) inhibition of binding in the presence of heparin or HS at 0.1-1 {mu}g/mL, but not by chondroitin sulfate, keratan sulfate, or hyaluronic acid at 10 {mu}g/mL, (ii) lack of binding to ECM pretreated with heparitinase, but not with chondroitinase ABC, and (iii) rapid release of up to 90% of ECM-bound FGF by exposure to heparin, HS, or heparitinase, but not to chondroitin sulfate, keratan sulfate, hyaluronic acid, or chondroitinase ABC. Oligosaccharides derived from depolymerized heparin, and as small as the tetrasaccharide, released the ECM-bound FGF, but there was little or no release of FGF by modified nonanticoagulant heparins such as totally desulfated heparin, N-desulfated heparin, and N-acetylated heparin. FGF released from ECM was biologically active, as indicated by its stimulation of cell proliferation and DNA synthesis in vascular endothelial cells and 3T3 fibroblasts. Similar results were obtained in studies on release of endogenous FGF-like mitogenic activity from Descement's membranes of bovine corneas. It is suggested that ECM storage and release of bFGF provide a novel mechanism for regulation of capillary blood vessel growth. Whereas ECM-bound FGF may be prevented from acting on endothelial cells, its displacement by heparin-like molecules and/or HS-degrading enzymes may elicit a neovascular response.

  20. Effect of the substituents of the neighboring ring in the conformational equilibrium of iduronate in heparin-like trisaccharides.

    PubMed

    Muñoz-García, Juan Carlos; López-Prados, Javier; Angulo, Jesús; Díaz-Contreras, Irene; Reichardt, Niels; de Paz, José L; Martín-Lomas, Manuel; Nieto, Pedro M

    2012-12-14

    Based on the structure of the regular heparin, we have prepared a smart library of heparin-like trisaccharides by incorporating some sulfate groups in the sequence α-D-GlcNS- (1-4)-α-L-Ido2S-(1-4)-α-D-GlcN. According to the 3D structure of heparin, which features one helix turn every four residues, this fragment corresponds to the minimum binding motif. We have performed a complete NMR study and found that the trisaccharides have a similar 3D structure to regular heparin itself, but their spectral properties are such that allow to extract very detailed information about distances and coupling constants as they are isotropic molecules. The characteristic conformational equilibrium of the central iduronate ring has been analyzed combining NMR and molecular dynamics and the populations of the conformers of the central iduronate ring have been calculated. We have found that in those compounds lacking the sulfate group at position 6 of the reducing end glucosamine, the population of (2)S(0) of the central iduronate residue is sensitive to the temperature decreasing to 19% at 278 K. On the contrary, the trisaccharides with 6-O-sulfate in the reducing end glucosamine keep the level of population constant with temperature circa 40% of (2)S(0) similar to that observed at room temperature. Another structural feature that has been revealed through this analysis is the larger flexibility of the L-IdoAS- D-GlcN glycosidic linkage, compared with the D-GlcNS-L-IdoA. We propose that this is the point where the heparin chain is bended to form structures far from the regular helix known as kink that have been proposed to play an important role in the specificity of the heparin-protein interaction. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Caracterisation of Titanium Nitride Layers Deposited by Reactive Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Popescu, Mihaela; Uţu, Dragoş

    2011-01-01

    Forming and cutting tools are subjected to the intense wear solicitations. Usually, they are either subject to superficial heat treatments or are covered with various materials with high mechanical properties. In recent years, thermal spraying is used increasingly in engineering area because of the large range of materials that can be used for the coatings. Titanium nitride is a ceramic material with high hardness which is used to cover the cutting tools increasing their lifetime. The paper presents the results obtained after deposition of titanium nitride layers by reactive plasma spraying (RPS). As deposition material was used titanium powder and as substratum was used titanium alloy (Ti6Al4V). Macroscopic and microscopic (scanning electron microscopy) images of the deposited layers and the X ray diffraction of the coatings are presented. Demonstration program with layers deposited with thickness between 68,5 and 81,4 μm has been achieved and presented.

  2. TiC-based coatings deposition using electric discharged plasma

    NASA Astrophysics Data System (ADS)

    Rahmatullin, I.; Sivkov, A.; Gerasimov, D.; Ivashutenko, A.; Shanenkova, J.

    2017-05-01

    The aim of this work was to research the possibility of using coaxial magneto plasma accelerator for TiC-coatings deposition on steel substrates. As a result, coatings with 0.01 m2 area was deposited. They were researched using XRD, SEM; also, the nanohardness on cross section of coating was measured. The influence of energy and carbon load on phase content, average hardness and microstructure is shown. It is established that the finest microstructure and average nanohardness is 15.3 GPa are achieved at energy W = 46.7 kJ and carbon load of 2.0 grams.

  3. Very high frequency plasma reactant for atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Oh, Il-Kwon; Yoo, Gilsang; Yoon, Chang Mo; Kim, Tae Hyung; Yeom, Geun Young; Kim, Kangsik; Lee, Zonghoon; Jung, Hanearl; Lee, Chang Wan; Kim, Hyungjun; Lee, Han-Bo-Ram

    2016-11-01

    Although plasma-enhanced atomic layer deposition (PE-ALD) results in several benefits in the formation of high-k dielectrics, including a low processing temperature and improved film properties compared to conventional thermal ALD, energetic radicals and ions in the plasma cause damage to layer stacks, leading to the deterioration of electrical properties. In this study, the growth characteristics and film properties of PE-ALD Al2O3 were investigated using a very-high-frequency (VHF) plasma reactant. Because VHF plasma features a lower electron temperature and higher plasma density than conventional radio frequency (RF) plasma, it has a larger number of less energetic reaction species, such as radicals and ions. VHF PE-ALD Al2O3 shows superior physical and electrical properties over RF PE-ALD Al2O3, including high growth per cycle, excellent conformality, low roughness, high dielectric constant, low leakage current, and low interface trap density. In addition, interlayer-free Al2O3 on Si was achieved in VHF PE-ALD via a significant reduction in plasma damage. VHF PE-ALD will be an essential process to realize nanoscale devices that require precise control of interfaces and electrical properties.

  4. Titanium dioxide thin films deposited by plasma enhanced atomic layer deposition for OLED passivation.

    PubMed

    Kim, Woong-Sun; Ko, Myoung-Gyun; Kim, Tae-Sub; Park, Sang-Kyun; Moon, Yeon-Keon; Lee, Su-Hwan; Park, Jae-Gun; Park, Jong-Wan

    2008-09-01

    Plasma enhanced atomic layer deposition (PEALD) of titanium dioxide thin films was conducted using Tetrakis dimethylamino titanium (TDMATi) and an oxygen plasma on a polyethersulfon (PES) substrate at a deposition temperature of 90 degrees C. The effects of the induced plasma power on passivation properties were investigated according to film thickness. The growth rate of the titanium dioxide film was 0.8 A/cycle, and the water vapor transmission rate (WTVR) for a 80 nm titanium dioxide film was 0.023 g/m2 day. The passivation performance of the titanium dioxide film was investigated using an organic light-emitting diode (OLED). The coated OLED lifetime was 90 h, 15 times longer than that of an uncoated sample.

  5. Plasma deposition and surface modification techniques for wear resistance

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1982-01-01

    The ion-assisted or plasma coating technology is discussed as it applies to the deposition of hard, wear resistant refractory compound films. Of the many sputtering and ion plating modes and configurations the reactive magnetron sputtering and the reactive triode ion plating techniques are the preferred ones to deposit wear resistant coatings for tribological applications. Both of these techniques incorporate additional means to enhance the ionization efficiency and chemical reaction to precision tailor desirable tribological characteristics. Interrelationships between film formation, structure, and ribological properties are strictly controlled by the deposition parameters and the substrate condition. The enhanced ionization contributes to the excellent adherence and coherence, reduced internal stresses and improved structural growth to form dense, cohesive, equiaxed grain structure for improved wear resistance and control.

  6. Plasma deposition of antimicrobial coating on organic polymer

    NASA Astrophysics Data System (ADS)

    Rżanek-Boroch, Zenobia; Dziadczyk, Paulina; Czajkowska, Danuta; Krawczyk, Krzysztof; Fabianowski, Wojciech

    2013-02-01

    Organic materials used for packing food products prevent the access of microorganisms or gases, like oxygen or water vapor. To prolong the stability of products, preservatives such as sulfur dioxide, sulfites, benzoates, nitrites and many other chemical compounds are used. To eliminate or limit the amount of preservatives added to food, so-called active packaging is sought for, which would limit the development of microorganisms. Such packaging can be achieved, among others, by plasma modification of a material to deposit on its surface substances inhibiting the growth of bacteria. In this work plasma modification was carried out in barrier discharge under atmospheric pressure. Sulfur dioxide or/and sodium oxide were used as the coating precursors. As a result of bacteriological studies it was found that sulfur containing coatings show a 16% inhibition of Salmonella bacteria growth and 8% inhibition of Staphylococcus aureus bacteria growth. Sodium containing coatings show worse (by 10%) inhibiting properties. Moreover, films with plasma deposited coatings show good sealing properties against water vapor. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  7. Filters for blocking macroparticles in plasma deposition apparatus

    DOEpatents

    Anders, Andre; Kolbeck, Jonathan

    2017-06-20

    This disclosure provides systems, methods, and apparatus related to blocking macroparticles in deposition processes utilizing plasmas. In one aspect, an apparatus includes a cathode, a substrate holder, a first magnet, a second magnet, and a structure. The cathode is configured to generate a plasma. The substrate holder is configured to hold a substrate. The first magnet is disposed proximate a first side of the cathode. The second magnet is disposed proximate a second side of the substrate holder. A magnetic field exists between the first magnet and the second magnet and a flow of the plasma substantially follows the magnetic field. The structure is disposed between the second side of the cathode and the first side of the substrate holder and is positioned proximate a region where the magnetic field between the first magnet and the second magnet is weak.

  8. Stress control of silicon nitride films deposited by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Li, Dong-ling; Feng, Xiao-fei; Wen, Zhi-yu; Shang, Zheng-guo; She, Yin

    2016-07-01

    Stress controllable silicon nitride (SiNx) films deposited by plasma enhanced chemical vapor deposition (PECVD) are reported. Low stress SiNx films were deposited in both high frequency (HF) mode and dual frequency (HF/LF) mode. By optimizing process parameters, stress free (-0.27 MPa) SiNx films were obtained with the deposition rate of 45.5 nm/min and the refractive index of 2.06. Furthermore, at HF/LF mode, the stress is significantly influenced by LF ratio and LF power, and can be controlled to be 10 MPa with the LF ratio of 17% and LF power of 150 W. However, LF power has a little effect on the deposition rate due to the interaction between HF power and LF power. The deposited SiNx films have good mechanical and optical properties, low deposition temperature and controllable stress, and can be widely used in integrated circuit (IC), micro-electro-mechanical systems (MEMS) and bio-MEMS.

  9. Investigations on the Nature of Ceramic Deposits in Plasma Spray-Physical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    He, W.; Mauer, G.; Gindrat, M.; Wäger, R.; Vaßen, R.

    2017-01-01

    In Plasma Spray-Physical Vapor Deposition (PS-PVD) process, major fractions of the feedstock powder can be evaporated so that coatings are deposited mainly from the vapor phase. In this work, Computational Fluid Dynamics (CFD) results indicate that such evaporation occurs significantly in the plasma torch nozzle and even nucleation and condensation of zirconia is highly possible there. Experimental work has been performed to investigate the nature of the deposits in the PS-PVD process, in particular coatings from condensate vapor and nano-sized clusters produced at two spraying distances of 1000 mm and 400 mm. At long spraying distance, columns in the coatings have pyramidal tops and very sharp faceted microstructures. When the spraying distance is reduced to 400 mm, the tops of columns become relatively flat and a faceted structure is not recognizable. XRD patterns show obvious preferred orientations of (110) and (002) in the coatings sprayed at 400 mm but only limited texture in the coatings sprayed at 1000 mm. Meanwhile, a non-line of sight coating was also investigated, which gives an example for pure vapor deposition. Based on these analyses, a vapor and cluster depositions are suggested to further explain the formation mechanisms of high-quality columnar-structured PS-PVD thermal barrier coatings which have already shown excellent performance in cyclic lifetime test.

  10. Diagnostic for Plasma Enhanced Chemical Vapor Deposition and Etch Systems

    NASA Technical Reports Server (NTRS)

    Cappelli, Mark A.

    1999-01-01

    In order to meet NASA's requirements for the rapid development and validation of future generation electronic devices as well as associated materials and processes, enabling technologies ion the processing of semiconductor materials arising from understanding etch chemistries are being developed through a research collaboration between Stanford University and NASA-Ames Research Center, Although a great deal of laboratory-scale research has been performed on many of materials processing plasmas, little is known about the gas-phase and surface chemical reactions that are critical in many etch and deposition processes, and how these reactions are influenced by the variation in operating conditions. In addition, many plasma-based processes suffer from stability and reliability problems leading to a compromise in performance and a potentially increased cost for the semiconductor manufacturing industry. Such a lack of understanding has hindered the development of process models that can aid in the scaling and improvement of plasma etch and deposition systems. The research described involves the study of plasmas used in semiconductor processes. An inductively coupled plasma (ICP) source in place of the standard upper electrode assembly of the Gaseous Electronics Conference (GEC) radio-frequency (RF) Reference Cell is used to investigate the discharge characteristics and chemistries. This ICP source generates plasmas with higher electron densities (approximately 10(exp 12)/cu cm) and lower operating pressures (approximately 7 mTorr) than obtainable with the original parallel-plate version of the GEC Cell. This expanded operating regime is more relevant to new generations of industrial plasma systems being used by the microelectronics industry. The motivation for this study is to develop an understanding of the physical phenomena involved in plasma processing and to measure much needed fundamental parameters, such as gas-phase and surface reaction rates. species

  11. Gas permeation barriers deposited by atmospheric pressure plasma enhanced atomic layer deposition

    SciTech Connect

    Hoffmann, Lukas Theirich, Detlef; Hasselmann, Tim; Räupke, André; Schlamm, Daniel; Riedl, Thomas

    2016-01-15

    This paper reports on aluminum oxide (Al{sub 2}O{sub 3}) thin film gas permeation barriers fabricated by atmospheric pressure atomic layer deposition (APPALD) using trimethylaluminum and an Ar/O{sub 2} plasma at moderate temperatures of 80 °C in a flow reactor. The authors demonstrate the ALD growth characteristics of Al{sub 2}O{sub 3} films on silicon and indium tin oxide coated polyethylene terephthalate. The properties of the APPALD-grown layers (refractive index, density, etc.) are compared to that deposited by conventional thermal ALD at low pressures. The films films deposited at atmospheric pressure show water vapor transmission rates as low as 5 × 10{sup −5} gm{sup −2}d{sup −1}.

  12. CMAS Interactions with Advanced Environmental Barrier Coatings Deposited via Plasma Spray- Physical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Harder, B. J.; Wiesner, V. L.; Zhu, D.; Johnson, N. S.

    2017-01-01

    Materials for advanced turbine engines are expected to have temperature capabilities in the range of 1370-1500C. At these temperatures the ingestion of sand and dust particulate can result in the formation of corrosive glass deposits referred to as CMAS. The presence of this glass can both thermomechanically and thermochemically significantly degrade protective coatings on metallic and ceramic components. Plasma Spray- Physical Vapor Deposition (PS-PVD) was used to deposit advanced environmental barrier coating (EBC) systems for investigation on their interaction with CMAS compositions. Coatings were exposed to CMAS and furnace tested in air from 1 to 50 hours at temperatures ranging from 1200-1500C. Coating composition and crystal structure were tracked with X-ray diffraction and microstructure with electron microscopy.

  13. Comparison of ammonia plasma and AlN passivation by plasma-enhanced atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Mattila, P.; Bosund, M.; Huhtio, T.; Lipsanen, H.; Sopanen, M.

    2012-03-01

    Surface passivation of GaAs by ammonia plasma and AlN fabricated by plasma-enhanced atomic layer deposition are compared. It is shown that the deposition temperature can be reduced to 150 °C and effective passivation is still achieved. Samples passivated by AlN fabricated at 150 °C show four times higher photoluminescence intensity and longer time-resolved photoluminescence lifetime than ammonia plasma passivated samples. The passivation effect is shown to last for months. The dependence of charge carrier lifetime and integrated photoluminescence intensity on AlN layer thickness is studied using an exponential model to describe the tunneling probability from the near-surface quantum well to the GaAs surface.

  14. Radio-frequency plasma chemical vapor deposition growth of diamond

    NASA Technical Reports Server (NTRS)

    Meyer, Duane E.; Dillon, Rodney O.; Woollam, John A.

    1989-01-01

    Plasma chemical vapor deposition (CVD) at 13.56 MHz has been used to produce diamond particles in two different inductively coupled systems with a mixture of methane and hydrogen. The effect of a diamondlike carbon (DLC) overcoating on silicon, niobium, and stainless-steel substrates has been investigated and in the case of silicon has been found to enhance particle formation as compared to uncoated polished silicon. In addition the use of carbon monoxide in hydrogen has been found to produce well-defined individual faceted particles as well as polycrystalline films on quartz and DLC coated silicon substrates. Plasma CVD is a competitive approach to production of diamond films. It has the advantage over microwave systems of being easily scaled to large volume and high power.

  15. Energy deposition in low-power coaxial plasma thrusters

    NASA Technical Reports Server (NTRS)

    Myers, R. M.; Kelly, A. J.; Jahn, R. G.

    1991-01-01

    An experimental examination of energy deposition in self-field, coaxial plasma thrusters revealed that the thrust efficiency ranged from 2-9 percent and that the dominant losses resulted from electrode heating and propellant ionization. Sensible enthalpy and radiative losses were negligible. Thruster specific impulse increased with current, ranging from 550-1750 seconds. Spectroscopic studies of the plume plasma showed that the electron temperature ranged from 0.5-2.5 eV and that the dominant species were singly and doubly ionized argon. Attempts to raise thruster efficiency by increasing the chamber pressure resulted in reduced electrode losses and lowered I(sp), but the thrust efficiency decreased because of a current redistribution that lowered the thrust beyond expectations.

  16. Gallium arsenide/gold nanostructures deposited using plasma method

    SciTech Connect

    Mangla, O.; Roy, S.; Annapoorni, S.

    2016-05-23

    The fabrication of gallium arsenide (GaAs) nanostructures on gold coated glass, quartz and silicon substrates using the high fluence and highly energetic ions has been reported. The high fluence and highly energetic ions are produced by the hot, dense and extremely non-equilibrium plasma in a modified dense plasma focus device. The nanostructures having mean size about 14 nm, 13 nm and 18 nm are deposited on gold coated glass, quartz and silicon substrates, respectively. The optical properties of nanostructures studied using absorption spectra show surface plasmon resonance peak of gold nanoparticles. In addition, the band-gap of GaAs nanoparticles is more than that of bulk GaAs suggesting potential applications in the field of optoelectronic and sensor systems.

  17. Energy deposition in low-power coaxial plasma thrusters

    NASA Technical Reports Server (NTRS)

    Myers, R. M.; Kelly, A. J.; Jahn, R. G.

    1991-01-01

    An experimental examination of energy deposition in self-field, coaxial plasma thrusters revealed that the thrust efficiency ranged from 2-9 percent and that the dominant losses resulted from electrode heating and propellant ionization. Sensible enthalpy and radiative losses were negligible. Thruster specific impulse increased with current, ranging from 550-1750 seconds. Spectroscopic studies of the plume plasma showed that the electron temperature ranged from 0.5-2.5 eV and that the dominant species were singly and doubly ionized argon. Attempts to raise thruster efficiency by increasing the chamber pressure resulted in reduced electrode losses and lowered I(sp), but the thrust efficiency decreased because of a current redistribution that lowered the thrust beyond expectations.

  18. Plasma-enhanced chemical vapor deposition of multiwalled carbon nanofibers

    NASA Technical Reports Server (NTRS)

    Matthews, Kristopher; Cruden, Brett A.; Chen, Bin; Meyyappan, M.; Delzeit, Lance

    2002-01-01

    Plasma-enhanced chemical vapor deposition is used to grow vertically aligned multiwalled carbon nanofibers (MWNFs). The graphite basal planes in these nanofibers are not parallel as in nanotubes; instead they exhibit a small angle resembling a stacked cone arrangement. A parametric study with varying process parameters such as growth temperature, feedstock composition, and substrate power has been conducted, and these parameters are found to influence the growth rate, diameter, and morphology. The well-aligned MWNFs are suitable for fabricating electrode systems in sensor and device development.

  19. Magnetically controlled deposition of metals using gas plasma. Final report

    SciTech Connect

    1998-04-02

    This is the first phase of a project that has the objective to develop a method of spraying materials on a substrate in a controlled manner to eliminate the waste and hazardous material generation inherent in present plating processes. The project is considering plasma spraying of metal on a substrate using magneto-hydrodynamics to control the plasma/metal stream. The process being developed is considering the use of commercially available plasma torches to generate the plasma/metal stream. The plasma stream is collimated, and directed using magnetic forces to the extent required for precise control of the deposition material. The project will be completed in phases. Phase one of the project, the subject of this grant, is the development of an analytical model that can be used to determine the feasibility of the process and to design a laboratory scale demonstration unit. The contracted time is complete, and the research is still continuing. This report provides the results obtained to date. As the model and calculations are completed those results will also be provided. This report contains the results of the computer code that have been completed to date. Results from a ASMEE Benchmark problem, flow over a backward step with heat transfer, Couette flow with magnetic forces, free jet flow are presented along with several other check calculations that are representative of the cases that were calculated in the course of the development process. The final cases that define a velocity field in the exit of a plasma spray torch with and without a magnetic field are in process. A separate program (SPRAY) has been developed that can track the plating material to the substrate and describe the distribution of the material on the substrate. When the jet calculations are complete SPRAY will be used to compare the distribution of material on the substrate with and without the effect of the magnetic focus.

  20. Atmospheric Plasma Deposition of Diamond-like Carbon Coatings

    SciTech Connect

    Ladwig, Angela

    2008-01-23

    There is great demand for thin functional coatings in the semiconductor, optics, electronics, medical, automotive and aerospace industries [1-13]. As fabricated components become smaller and more complex, the properties of the materials’ surface take on greater importance. Thin coatings play a key role in tailoring surfaces to give them the desired hardness, wear resistance, chemical inertness, and electrical characteristics. Diamond-like carbon (DLC) coatings possess an array of desirable properties, including outstanding abrasion and wear resistance, chemical inertness, hardness, a low coefficient of friction and exceptionally high dielectric strength [14-22]. Diamond-like carbon is considered to be an amorphous material, containing a mixture of sp2 and sp3 bonded carbon. Based on the percentage of sp3 carbon and the hydrogen content, four different types of DLC coatings have been identified: tetrahedral carbon (ta-C), hydrogenated amorphous carbon (a-C:H) hard, a-C:H soft, and hydrogenated tetrahedral carbon (ta-C:H) [20,24,25]. Possessing the highest hardness of 80 GPa, ta-C possesses an sp3 carbon content of 80 to 88u%, and no appreciable hydrogen content whereas a-C:H soft possesses a hardness of less than 10 GPa, contains an sp3 carbon content of 60% and a hydrogen content between 30 to 50%. Methods used to deposit DLC coatings include ion beam deposition, cathodic arc spray, pulsed laser ablation, argon ion sputtering, and plasma-enhanced chemical vapor deposition [73-83]. Researchers contend that several advantages exist when depositing DLC coatings in a low-pressure environment. For example, ion beam processes are widely utilized since the ion bombardment is thought to promote denser sp3-bonded carbon networks. Other processes, such as sputtering, are better suited for coating large parts [29,30,44]. However, the deposition of DLC in a vacuum system has several disadvantages, including high equipment cost and restrictions on the size and shape of

  1. Superconducting niobium titanium nitride thin films deposited by plasma-enhanced atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Yemane, Y. T.; Sowa, M. J.; Zhang, J.; Ju, L.; Deguns, E. W.; Strandwitz, N. C.; Prinz, F. B.; Provine, J.

    2017-09-01

    NbTiN has a variety of superconducting applications, ranging from RF cavities to single-photon detectors. Here, we systematically investigated the plasma-enhanced atomic layer deposition (PEALD) of Nb x Ti{}1-x{{N}} with the organometallic precursors (t-butylimido) tris(diethyamido) niobium(V) and tetrakis (dimethylamido) titanium in conjunction with a remote H2/N2 plasma. Deposited film properties have been studied as a function of the ratio of Nb to Ti precursor pulses within each ALD supercycle. PEALD NbTiN films were characterized with spectroscopic ellipsometry (thickness, optical properties), four point probe (resistivity), x-ray photoelectron spectroscopy (composition), x-ray reflectivity (density and thickness), x-ray diffraction (crystallinity), and superconductivity measurements. The PEALD process has shown distinct advantages over deposition of superconducting films via thermal ALD or sputtering, for example a lower processing temperature and more efficient control of film composition. This control of film composition enabled the tuning of electrical and superconducting properties, such as varying the superconducting critical temperature T C between 6.9 and 13.2 K.

  2. Friction and wear of plasma-deposited diamond films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wu, Richard L. C.; Garscadden, Alan; Barnes, Paul N.; Jackson, Howard E.

    1993-01-01

    Reciprocating sliding friction experiments in humid air and in dry nitrogen and unidirectional sliding friction experiments in ultrahigh vacuum were conducted with a natural diamond pin in contact with microwave-plasma-deposited diamond films. Diamond films with a surface roughness (R rms) ranging from 15 to 160 nm were produced by microwave-plasma-assisted chemical vapor deposition. In humid air and in dry nitrogen, abrasion occurred when the diamond pin made grooves in the surfaces of diamond films, and thus the initial coefficients of friction increased with increasing initial surface roughness. The equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. In vacuum the friction for diamond films contacting a diamond pin arose primarily from adhesion between the sliding surfaces. In these cases, the initial and equilibrium coefficients of friction were independent of the initial surface roughness of the diamond films. The equilibrium coefficients of friction were 0.02 to 0.04 in humid air and in dry nitrogen, but 1.5 to 1.8 in vacuum. The wear factor of the diamond films depended on the initial surface roughness, regardless of environment; it increased with increasing initial surface roughness. The wear factors were considerably higher in vacuum than in humid air and in dry nitrogen.

  3. Fluorinated carboxylic membranes deposited by plasma enhanced chemical vapour deposition for fuel cell applications

    NASA Astrophysics Data System (ADS)

    Thery, J.; Martin, S.; Faucheux, V.; Le Van Jodin, L.; Truffier-Boutry, D.; Martinent, A.; Laurent, J.-Y.

    Among the fuel cell technologies, the polymer electrolyte membrane fuel cells (PEMFCs) are particularly promising because they are energy-efficient, clean, and fuel-flexible (i.e., can use hydrogen or methanol). The great majority of PEM fuel cells rely on a polymer electrolyte from the family of perfluorosulfonic acid membranes, nevertheless alternative materials are currently being developed, mainly to offer the alternative workout techniques which are required for the portable energy sources. Plasma polymerization represents a good solution, as it offers the possibility to deposit thin layer with an accurate and homogeneous thickness, even on 3D surfaces. In this paper, we present the results for the growth of proton conductive fluoro carboxylic membranes elaborated by plasma enhanced chemical vapour deposition. These membranes present conductivity values of the same order than the one of Nafion ®. The properties of the membrane, such as the chemical composition, the ionic conductivity, the swelling behaviour and the permeability were correlated to the plasma process parameters. The membranes were integrated in fuel cells on porous substrates and we present here the results regarding the barrier effect and the power output. Barrier effect similar to those of 40 μm Nafion ® layers was reached for 10 μm thick carboxylic membranes. Power outputs around 3 mW cm -2 were measured. We discuss the results regarding the gas barrier effect and the power outputs.

  4. Selective Plasma Deposition of Fluorocarbon Films on SAMs

    NASA Technical Reports Server (NTRS)

    Crain, Mark M., III; Walsh, Kevin M.; Cohn, Robert W.

    2006-01-01

    A dry plasma process has been demonstrated to be useful for the selective modification of self-assembled monolayers (SAMs) of alkanethiolates. These SAMs are used, during the fabrication of semiconductor electronic devices, as etch masks on gold layers that are destined to be patterned and incorporated into the devices. The selective modification involves the formation of fluorocarbon films that render the SAMs more effective in protecting the masked areas of the gold against etching by a potassium iodide (KI) solution. This modification can be utilized, not only in the fabrication of single electronic devices but also in the fabrication of integrated circuits, microelectromechanical systems, and circuit boards. In the steps that precede the dry plasma process, a silicon mold in the desired pattern is fabricated by standard photolithographic techniques. A stamp is then made by casting polydimethylsiloxane (commonly known as silicone rubber) in the mold. The stamp is coated with an alkanethiol solution, then the stamp is pressed on the gold layer of a device to be fabricated in order to deposit the alkanethiol to form an alkanethiolate SAM in the desired pattern (see figure). Next, the workpiece is exposed to a radio-frequency plasma generated from a mixture of CF4 and H2 gases. After this plasma treatment, the SAM is found to be modified, while the exposed areas of gold remain unchanged. This dry plasma process offers the potential for forming masks superior to those formed in a prior wet etching process. Among the advantages over the wet etching process are greater selectivity, fewer pin holes in the masks, and less nonuniformity of the masks. The fluorocarbon films formed in this way may also be useful as intermediate layers for subsequent fabrication steps and as dielectric layers to be incorporated into finished products.

  5. Nitrogen plasma instabilities and the growth of silicon nitride by electron cyclotron resonance microwave plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Pool, F. S.

    1997-03-01

    Nitrogen plasma instabilities have been identified through fluctuations in the ion current density and substrate floating potential. The behavior of the plasma instabilities was found to be confined to the pressure regime 0.9 mTorrplasmas occurred following the transition from an underdense to overdense plasma, where an overdense plasma is defined for densities greater than the critical density nc=7.4×1010 cm-3. The instabilities are a consequence of the nonlinear dynamics present in electron cyclotron resonance (ECR) plasmas and indicative of a transition between plasma modes as the pressure increases from 0.9 to 1.6 mTorr. The plasma instabilities are suppressed with the introduction of silane for the deposition of silicon nitride, although the plasma still undergoes a transition from an underdense to overdense plasma at 1.0 mTorr. The transition pressure delineated regions of poor and optimum electrical properties of silicon nitride films deposited from a dilute nitrogen-silane (N2/SiH4=5) plasma. To evaluate growth conditions, the flux of energetic ions to deposited atoms was approximated by examination of the ratio of ion current density to deposition rate. This ratio was found to be well correlated to the electrical properties of ECR microwave plasma deposited silicon nitride films for pressures above the underdense to overdense transition at 1.0 mTorr.

  6. Robust Ultralow-k Dielectric (Fluorocarbon) Deposition by Microwave Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Kikuchi, Yoshiyuki; Miyatani, Kotaro; Kobayashi, Yasuo; Kawamura, Kohei; Nemoto, Takenao; Nakamura, Masahiro; Matsumoto, Hirokazu; Ito, Azumi; Shirotori, Akihide; Nozawa, Toshihisa; Matsuoka, Takaaki

    2012-05-01

    A robust fluorocarbon film was successfully deposited on a substrate at a temperature above 400 °C by the new microwave plasma-enhanced chemical vapor deposition (MWPE-CVD) method using the linear C5F8 precursor instead of a conventional cyclic C5F8 one. The fluorocarbon performed keeping the dielectric constant low as a value of 2.25 by controlling the molecular structure forming cross-linked poly(tetrafluoroethylene) (PTFE) chains with configurational carbon atoms. The novel fluorocarbon demonstrates less fluorine degassing at an elevated temperature, with high mechanical strength and without degradation of adhesion of the fluorocarbon film to SiCN and SiOx stacked films after thermal stress at 400 °C and 1 atm N2 for 1 h. Consequently, this robust fluorocarbon film is considered a promising candidate for general porous silicon materials with applications to practical integration processes as an interlayer dielectric.

  7. Pulsed and continuous wave acrylic acid radio frequency plasma deposits: plasma and surface chemistry.

    PubMed

    Voronin, Sergey A; Zelzer, Mischa; Fotea, Catalin; Alexander, Morgan R; Bradley, James W

    2007-04-05

    Plasma polymers have been formed from acrylic acid using a pulsed power source. An on-pulse duration of 100 micros was used with a range of discharge off-times between 0 (continuous wave) and 20,000 micros. X-ray photoelectron spectroscopy (XPS) has been used in combination with trifluoroethanol (TFE) derivatization to quantify the surface concentration of the carboxylic acid functionality in the deposit. Retention of this functionality from the monomer varied from 2% to 65%. When input power was expressed as the time-averaged energy per monomer molecule, E(mean), the deposit chemistry achieved could be described using a single relationship for all deposition conditions. Deposition rates were monitored using a quartz crystal microbalance, which revealed a range from 20 to 200 microg m(-2) s(-1), and these fell as COOH functional retention increased. The flow rate was found to be the major determinant of the deposition rate, rather than being uniquely defined by E(mean), connected to the rate at which fresh monomer enters the system in the monomer deficient regime. The neutral species were collected in a time-averaged manner. As the energy delivered per molecule in the system (E(mean)) decreased, the amount of intact monomer increased, with the average neutral mass approaching 72 amu as E(mean) tends to zero. No neutral oligomeric species were detected. Langmuir probes have been used to determine the temporal evolution of the density and temperature of the electrons in the plasma and the plasma potential adjacent to the depositing film. It has been found that even 500 micros into the afterglow period that ionic densities are still significant, 5-10% of the on-time density, and that ion accelerating sheath potentials fall from 40 V in the on-time to a few volts in the off-time. We have made the first detailed, time- and energy-resolved mass spectrometry measurements in depositing acrylic acid plasma. These have allowed us to identify and quantify the positive ion

  8. Carbon Nanotubes/Nanofibers by Plasma Enhanced Chemical Vapour Deposition

    NASA Technical Reports Server (NTRS)

    Teo, K. B. K.; Hash, D. B.; Bell, M. S.; Chhowalla, M.; Cruden, B. A.; Amaratunga, G. A. J.; Meyyappan, M.; Milne, W. I.

    2005-01-01

    Plasma enhanced chemical vapour deposition (PECVD) has been recently used for the production of vertically aligned carbon nanotubedfibers (CN) directly on substrates. These structures are potentially important technologically as electron field emitters (e.g. microguns, microwave amplifiers, displays), nanoelectrodes for sensors, filter media, superhydrophobic surfaces and thermal interface materials for microelectronics. A parametric study on the growth of CN grown by glow discharge dc-PECVD is presented. In this technique, a substrate containing thin film Ni catalyst is exposed to C2H2 and NH3 gases at 700 C. Without plasma, this process is essentially thermal CVD which produces curly spaghetti-like CN as seen in Fig. 1 (a). With the plasma generated by biasing the substrate at -6OOV, we observed that the CN align vertically during growth as shown in Fig. l(b), and that the magnitude of the applied substrate bias affects the degree of alignment. The thickness of the thin film Ni catalyst was found to determine the average diameter and inversely the length of the CN. The yield and density of the CN were controlled by the use of different diffusion barrier materials under the Ni catalyst. Patterned CN growth [Fig. l(c)], with la variation in CN diameter of 4.1% and 6.3% respectively, is achieved by lithographically defining the Ni thin film prior to growth. The shape of the structures could be varied from very straight nanotube-like to conical tip-like nanofibers by increasing the ratio of C2H2 in the gas flow. Due to the plasma decomposition of C2H2, amorphous carbon (a-C) is an undesirable byproduct which could coat the substrate during CN growth. Using a combination of depth profiled Auger electron spectroscopy to study the substrate and in-situ mass spectroscopy to examine gas phase neutrals and ions, the optimal conditions for a-C free growth of CN is determined.

  9. Physical processes and modeling of plasma deposition and hardening of coatings-switched electrical parameters

    NASA Astrophysics Data System (ADS)

    Kadyrmetov, A. M.; Sharifullin, S. N.

    2016-11-01

    This paper presents the results of simulation of plasma deposition and hardening of coatings in modulating the electrical parameters. Mathematical models are based on physical models of gas-dynamic mechanisms more dynamic and thermal processes of the plasma jet. As an example the modeling of dynamic processes of heterogeneous plasma jet, modulated current pulses indirect arc plasma torch.

  10. Coaxial carbon plasma gun deposition of amorphous carbon films

    NASA Technical Reports Server (NTRS)

    Sater, D. M.; Gulino, D. A.; Rutledge, S. K.

    1984-01-01

    A unique plasma gun employing coaxial carbon electrodes was used in an attempt to deposit thin films of amorphous diamond-like carbon. A number of different structural, compositional, and electrical characterization techniques were used to characterize these films. These included scanning electron microscopy, scanning transmission electron microscopy, X ray diffraction and absorption, spectrographic analysis, energy dispersive spectroscopy, and selected area electron diffraction. Optical absorption and electrical resistivity measurements were also performed. The films were determined to be primarily amorphous, with poor adhesion to fused silica substrates. Many inclusions of particulates were found to be present as well. Analysis of these particulates revealed the presence of trace impurities, such as Fe and Cu, which were also found in the graphite electrode material. The electrodes were the source of these impurities. No evidence of diamond-like crystallite structure was found in any of the film samples. Details of the apparatus, experimental procedure, and film characteristics are presented.

  11. High growth rate homoepitaxial diamond film deposition at high temperatures by microwave plasma-assisted chemical vapor deposition

    NASA Technical Reports Server (NTRS)

    Vohra, Yogesh K. (Inventor); McCauley, Thomas S. (Inventor)

    1997-01-01

    The deposition of high quality diamond films at high linear growth rates and substrate temperatures for microwave-plasma chemical vapor deposition is disclosed. The linear growth rate achieved for this process is generally greater than 50 .mu.m/hr for high quality films, as compared to rates of less than 5 .mu.m/hr generally reported for MPCVD processes.

  12. High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2014-01-01

    Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

  13. Ti-doped hydrogenated diamond like carbon coating deposited by hybrid physical vapor deposition and plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lee, Na Rae; Sle Jun, Yee; Moon, Kyoung Il; Sunyong Lee, Caroline

    2017-03-01

    Diamond-like carbon films containing titanium and hydrogen (Ti-doped DLC:H) were synthesized using a hybrid technique based on physical vapor deposition (PVD) and plasma enhanced chemical vapor deposition (PECVD). The film was deposited under a mixture of argon (Ar) and acetylene gas (C2H2). The amount of Ti in the Ti-doped DLC:H film was controlled by varying the DC power of the Ti sputtering target ranging from 0 to 240 W. The composition, microstructure, mechanical and chemical properties of Ti-doped DLC:H films with varying Ti concentrations, were investigated using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nano indentation, a ball-on-disk tribometer, a four-point probe system and dynamic anodic testing. As a result, the optimum composition of Ti in Ti-doped DLC:H film using our hybrid method was found to be a Ti content of 18 at. %, having superior electrical conductivity and high corrosion resistance, suitable for bipolar plates. Its hardness value was measured to be 25.6 GPa with a low friction factor.

  14. Plasma enhanced metalorganic chemical vapor deposition of amorphous aluminum nitride

    NASA Astrophysics Data System (ADS)

    Harris, H.; Biswas, N.; Temkin, H.; Gangopadhyay, S.; Strathman, M.

    2001-12-01

    Plasma enhanced deposition of amorphous aluminum nitride (AlN) using trimethylaluminum, hydrogen, and nitrogen was performed in a capacitively coupled plasma system. Temperature was varied from 350 to 550 °C, and pressure dependence of the film structure was investigated. Films were characterized by Fourier transform infrared, Rutherford backscattering (RBS), ellipsometry, and x-ray diffraction (XRD). The films are amorphous in nature, as indicated by XRD. Variations in the refractive index were observed in ellipsometric measurements, which is explained by the incorporation of carbon in the films, and confirmed by RBS. Capacitance-voltage, conductance-voltage (G-V), and current-voltage measurements were performed to reveal bulk and interface electrical properties. The electrical properties showed marked dependence on processing conditions of the AlN films. Clear peaks as observed in the G-V characteristics indicated that the losses are predominantly due to interface states. The interface state density ranged between 1010 and 1011eV-1 cm-2. Annealing in hydrogen resulted in lowering of interface state density values.

  15. Energy deposition in low power coaxial plasma thrusters

    NASA Astrophysics Data System (ADS)

    Myers, Roger Metcalf

    The energy deposition in steady-state, low power, coaxial plasma thrusters operated between 10 and 30 kW with argon and nitrogen propellants was studied experimentally and analytically. The major energy sinks were found to be electrode losses (primarily anode), propellant ionization, and thrust. Performance measurements showed the efficiency and specific impulse to vary between two and ten percent and 500 and 1200 seconds, respectively, as functions of thruster current level, propellant flow rate, and thruster geometry. Thrust was found to increase quadratically with current, in agreement with theoretical models of self-field electromagnetic thrusters. Spectroscopic studies of the plasma exhaust with argon propellant showed it to consist primarily of singly and doubly ionized argon, with an electron temperature between 1.2 and 1.7 eV and electron densities between 2 x 10 (exp 13) cu cm and 5 x 10 (exp 13) cu cm. Floating potential measurements showed the anode fall voltage to be between 65 and 95 percent of the total thruster voltage depending on thruster geometry, propellant, and current level. Non-intrusive cathode surface temperature and erosion measurements revealed that the cathode energy balance was governed by electron cooling, surface radiation and conduction through the cathode base. Comparisons of these new results with data from megawatt class, quasi-steady magnetoplasmadynamic thrusters revealed similarities between the plasma properties and acceleration mechanisms of the devices, but showed they have dramatically different anode power fractions. Attempts to increase thruster efficiency by decreasing the chamber radius were not successful, indicating that major changes in thruster design and/or power level will be required to achieve high efficiency, high specific impulse operation.

  16. Characteristics of silicon nitride deposited by VHF (162 MHz)-plasma enhanced chemical vapor deposition using a multi-tile push-pull plasma source

    NASA Astrophysics Data System (ADS)

    Kim, Ki Seok; Sirse, Nishant; Kim, Ki Hyun; Rogers Ellingboe, Albert; Kim, Kyong Nam; Yeom, Geun Young

    2016-10-01

    To prevent moisture and oxygen permeation into flexible organic electronic devices formed on substrates, the deposition of an inorganic diffusion barrier material such as SiN x is important for thin film encapsulation. In this study, by a very high frequency (162 MHz) plasma-enhanced chemical vapor deposition (VHF-PECVD) using a multi-tile push-pull plasma source, SiN x layers were deposited with a gas mixture of NH3/SiH4 with/without N2 and the characteristics of the plasma and the deposited SiN x film as the thin film barrier were investigated. Compared to a lower frequency (60 MHz) plasma, the VHF (162 MHz) multi-tile push-pull plasma showed a lower electron temperature, a higher vibrational temperature, and higher N2 dissociation for an N2 plasma. When a SiN x layer was deposited with a mixture of NH3/SiH4 with N2 at a low temperature of 100 °C, a stoichiometric amorphous Si3N4 layer with very low Si-H bonding could be deposited. The 300 nm thick SiN x film exhibited a low water vapor transmission rate of 1.18  ×  10-4 g (m2 · d)-1, in addition to an optical transmittance of higher than 90%.

  17. Note: Sample holder with open area for increased deposition rate in plasma immersion ion implantation and deposition

    NASA Astrophysics Data System (ADS)

    Flege, S.; Hatada, R.; Derepa, A.; Dietz, C.; Ensinger, W.; Baba, K.

    2017-09-01

    A sample holder with a large open area offers several benefits when used in the process of plasma immersion ion implantation and deposition in which the plasma is generated by a high voltage applied to the sample holder: The ignition voltage of the plasma is lower, and the deposition rate can be several times higher than in the case of a normal plate-like holder. There is a more pronounced edge effect regarding the film thickness. Other film properties are also affected; for diamond-like carbon films, the film structure exhibits more disorder. The hardness of the samples is similar, with the surfaces of the samples being very smooth.

  18. Host range and receptor utilization of canine distemper virus analyzed by recombinant viruses: Involvement of heparin-like molecule in CDV infection.

    PubMed

    Fujita, Kentaro; Miura, Ryuichi; Yoneda, Misako; Shimizu, Fusako; Sato, Hiroki; Muto, Yuri; Endo, Yasuyuki; Tsukiyama-Kohara, Kyoko; Kai, Chieko

    2007-03-15

    We constructed recombinant viruses expressing enhanced green fluorescent protein (EGFP) or firefly luciferase from cDNA clones of the canine distemper virus (CDV) (a Japanese field isolate, Yanaka strain). Using these viruses, we examined susceptibilities of different cell lines to CDV infection. The results revealed that the recombinant CDVs can infect a broad range of cell lines. Infectivity inhibition assay using a monoclonal antibody specific to the human SLAM molecule indicated that the infection of B95a cells with these recombinant CDVs is mainly mediated by SLAM but the infection of 293 cell lines with CDV is not, implying the presence of one or more alternative receptors for CDV in non-lymphoid tissue. Infection of 293 cells with the recombinant CDV was inhibited by soluble heparin, and the recombinant virus bound to immobilized heparin. Both F and H proteins of CDV could bind to immobilized heparin. These results suggest that heparin-like molecules are involved in CDV infection.

  19. Practical silicon deposition rules derived from silane monitoring during plasma-enhanced chemical vapor deposition

    SciTech Connect

    Bartlome, Richard De Wolf, Stefaan; Demaurex, Bénédicte; Ballif, Christophe; Amanatides, Eleftherios; Mataras, Dimitrios

    2015-05-28

    We clarify the difference between the SiH{sub 4} consumption efficiency η and the SiH{sub 4} depletion fraction D, as measured in the pumping line and the actual reactor of an industrial plasma-enhanced chemical vapor deposition system. In the absence of significant polysilane and powder formation, η is proportional to the film growth rate. Above a certain powder formation threshold, any additional amount of SiH{sub 4} consumed translates into increased powder formation rather than into a faster growing Si film. In order to discuss a zero-dimensional analytical model and a two-dimensional numerical model, we measure η as a function of the radio frequency (RF) power density coupled into the plasma, the total gas flow rate, the input SiH{sub 4} concentration, and the reactor pressure. The adjunction of a small trimethylboron flow rate increases η and reduces the formation of powder, while the adjunction of a small disilane flow rate decreases η and favors the formation of powder. Unlike η, D is a location-dependent quantity. It is related to the SiH{sub 4} concentration in the plasma c{sub p}, and to the phase of the growing Si film, whether the substrate is glass or a c-Si wafer. In order to investigate transient effects due to the RF matching, the precoating of reactor walls, or the introduction of a purifier in the gas line, we measure the gas residence time and acquire time-resolved SiH{sub 4} density measurements throughout the ignition and the termination of a plasma.

  20. Utility of dual frequency hybrid source for plasma and radical generation in plasma enhanced chemical vapor deposition process

    NASA Astrophysics Data System (ADS)

    Shin, Kyung Sik; Bhusan Sahu, Bibhuti; Geon Han, Jeon; Hori, Masaru

    2015-07-01

    Looking into the aspect of material processing, this work evaluates alternative plasma concepts in SiH4/H2 plasmas to investigate the radical and plasma generation in the plasma enhanced chemical vapor deposition (PECVD) synthesis of nanocrystalline Si (nc-Si:H). Simultaneous measurements by vacuum ultraviolet absorption spectroscopy (VUVAS), optical emission spectroscopy (OES), and radio frequency (RF) compensated Langmuir probe (LP) reveal that RF/ultrahigh frequency (UHF) hybrid source can efficiently produce H radicals and plasmas that are accountable for nc-Si:H film synthesis. The efficacy of hybrid plasmas is also discussed.

  1. Human recombinant interleukin-1 beta- and tumor necrosis factor alpha-mediated suppression of heparin-like compounds on cultured porcine aortic endothelial cells

    SciTech Connect

    Kobayashi, M.; Shimada, K.; Ozawa, T. )

    1990-09-01

    Cytokines are known to tip the balance of the coagulant-anticoagulant molecules on the endothelial cell surface toward intravascular coagulation. Their effects on endothelial cell surface-associated heparin-like compounds have not been examined yet. Incorporation of (35S)sulfate into heparan sulfate on cultured porcine aortic endothelial cells was suppressed by human recombinant interleukin-1 beta (rIL-1 beta) or tumor necrosis factor alpha (rTNF alpha) in a dose- and time-dependent manner with little effect on cell number, protein content, and (3H)leucine incorporation of cells. Maximal inhibition was achieved by incubation of cells with 100 ng/ml of rIL-1 beta or 5 ng/ml of rTNF alpha for 12-24 hours, resulting in a reduction of the synthesis of heparan sulfate on the cell surface by approximately 50%. The dose dependency was consistent with that seen in the stimulation of endothelial cell procoagulant activity by each cytokine. The suppression of heparan sulfate synthesis was sustained for at least 48 hours after pretreatment of cells with cytokines and was unchanged after the addition of indomethacin or polymyxin B. The rate of degradation of prelabeled 35S-heparan sulfate on the cell surface was not altered by cytokine treatments. Neither the size, the net negative charge, nor the proportion of the molecule with high affinity for antithrombin III of endothelial cell heparan sulfate was changed by cytokines. Furthermore, specific binding of 125I-labeled antithrombin III to the endothelial cell surface was reduced to 40-60% of control by cytokines. In parallel with reduction in binding, antithrombin III cofactor activity was partially diminished in cytokine-treated endothelial cells. Thus, cytokine-mediated suppression of heparin-like substance on endothelial cells appears to be another cytokine-inducible endothelial effects affecting coagulation.

  2. Analysis of hydrogen plasma in a microwave plasma chemical vapor deposition reactor

    NASA Astrophysics Data System (ADS)

    Shivkumar, G.; Tholeti, S. S.; Alrefae, M. A.; Fisher, T. S.; Alexeenko, A. A.

    2016-03-01

    The aim of this work is to build a numerical model of hydrogen plasma inside a microwave plasma chemical vapor deposition system. This model will help in understanding and optimizing the conditions for the growth of carbon nanostructures. A 2D axisymmetric model of the system is implemented using the finite element high frequency Maxwell solver and the heat transfer solver in COMSOL Multiphysics. The system is modeled to study variation in parameters with reactor geometry, microwave power, and gas pressure. The results are compared with experimental measurements from the Q-branch of the H2 Fulcher band of hydrogen using an optical emission spectroscopy technique. The parameter γ in Füner's model is calibrated to match experimental observations at a power of 500 W and 30 Torr. Good agreement is found between the modeling and experimental results for a wide range of powers and pressures. The gas temperature exhibits a weak dependence on power and a strong dependence on gas pressure. The inclusion of a vertical dielectric pillar that concentrates the plasma increases the maximum electron temperature by 70%, the maximum gas temperature by 50%, and the maximum electron number density by 70% when compared to conditions without the pillar at 500 W and 30 Torr. Experimental observations also indicate intensified plasma with the inclusion of a pillar.

  3. Analysis of hydrogen plasma in a microwave plasma chemical vapor deposition reactor

    SciTech Connect

    Shivkumar, G.; Tholeti, S. S.; Alexeenko, A. A.; Alrefae, M. A.; Fisher, T. S.

    2016-03-21

    The aim of this work is to build a numerical model of hydrogen plasma inside a microwave plasma chemical vapor deposition system. This model will help in understanding and optimizing the conditions for the growth of carbon nanostructures. A 2D axisymmetric model of the system is implemented using the finite element high frequency Maxwell solver and the heat transfer solver in COMSOL Multiphysics. The system is modeled to study variation in parameters with reactor geometry, microwave power, and gas pressure. The results are compared with experimental measurements from the Q-branch of the H{sub 2} Fulcher band of hydrogen using an optical emission spectroscopy technique. The parameter γ in Füner's model is calibrated to match experimental observations at a power of 500 W and 30 Torr. Good agreement is found between the modeling and experimental results for a wide range of powers and pressures. The gas temperature exhibits a weak dependence on power and a strong dependence on gas pressure. The inclusion of a vertical dielectric pillar that concentrates the plasma increases the maximum electron temperature by 70%, the maximum gas temperature by 50%, and the maximum electron number density by 70% when compared to conditions without the pillar at 500 W and 30 Torr. Experimental observations also indicate intensified plasma with the inclusion of a pillar.

  4. Radio frequency plasma power dependence of the moisture permeation barrier characteristics of Al{sub 2}O{sub 3} films deposited by remote plasma atomic layer deposition

    SciTech Connect

    Jung, Hyunsoo; Choi, Hagyoung; Lee, Sanghun; Jeon, Heeyoung; Jeon, Hyeongtag

    2013-11-07

    In the present study, we investigated the gas and moisture permeation barrier properties of Al{sub 2}O{sub 3} films deposited on polyethersulfone films (PES) by capacitively coupled plasma (CCP) type Remote Plasma Atomic Layer Deposition (RPALD) at Radio Frequency (RF) plasma powers ranging from 100 W to 400 W in 100 W increments using Trimethylaluminum [TMA, Al(CH{sub 3}){sub 3}] as the Al source and O{sub 2} plasma as the reactant. To study the gas and moisture permeation barrier properties of 100-nm-thick Al{sub 2}O{sub 3} at various plasma powers, the Water Vapor Transmission Rate (WVTR) was measured using an electrical Ca degradation test. WVTR decreased as plasma power increased with WVTR values for 400 W and 100 W of 2.6 × 10{sup −4} gm{sup −2}day{sup −1} and 1.2 × 10{sup −3} gm{sup −2}day{sup −1}, respectively. The trends for life time, Al-O and O-H bond, density, and stoichiometry were similar to that of WVTR with improvement associated with increasing plasma power. Further, among plasma power ranging from 100 W to 400 W, the highest power of 400 W resulted in the best moisture permeation barrier properties. This result was attributed to differences in volume and amount of ion and radical fluxes, to join the ALD process, generated by O{sub 2} plasma as the plasma power changed during ALD process, which was determined using a plasma diagnosis technique called the Floating Harmonic Method (FHM). Plasma diagnosis by FHM revealed an increase in ion flux with increasing plasma power. With respect to the ALD process, our results indicated that higher plasma power generated increased ion and radical flux compared with lower plasma power. Thus, a higher plasma power provides the best gas and moisture permeation barrier properties.

  5. Electrochromic Devices Deposited on Low-Temperature Plastics by Plasma-Enhanced Chemical Vapor Deposition

    SciTech Connect

    Robbins, Joshua; Seman, Michael

    2005-09-20

    Electrochromic windows have been identified by the Basic energy Sciences Advisory committee as an important technology for the reduction of energy spent on heating and cooling in residential and commercial buildings. Electrochromic devices have the ability to reversibly alter their optical properties in response to a small electric field. By blocking ultraviolet and infrared radiation, while modulating the incoming visible radiation, electrochromics could reduce energy consumption by several Quads per year. This amounts to several percent of the total annual national energy expenditures. The purpose of this project was to demonstrate proof of concept for using plasma-enhanced chemical vapor deposition (PECVD) for depositing all five layers necessary for full electrochromic devices, as an alternative to sputtering techniques. The overall goal is to produce electrochromic devices on flexible polymer substrates using PECVD to significantly reduce the cost of the final product. We have successfully deposited all of the films necessary for a complete electrochromic devices using PECVD. The electrochromic layer, WO3, displayed excellent change in visible transmission with good switching times. The storage layer, V2O5, exhibited a high storage capacity and good clear state transmission. The electrolyte, Ta2O5, was shown to functional with good electrical resistivity to go along with the ability to transfer Li ions. There were issues with leakage over larger areas, which can be address with further process development. We developed a process to deposit ZnO:Ga with a sheet resistance of < 50 W/sq. with > 90% transmission. Although we were not able to deposit on polymers due to the temperatures required in combination with the inverted position of our substrates. Two types of full devices were produced. Devices with Ta2O5 were shown to be functional using small aluminum dots as the top contact. The polymer electrolyte devices were shown to have a clear state transmission of

  6. Characterization of Carbon Deposits Formed During Plasma Pyrolysis of Xinjiang Candle Coal

    NASA Astrophysics Data System (ADS)

    Zhu, Guilin; Meng, Yuedong; Shu, Xingsheng; Fang, Shidong

    2009-08-01

    Carbon deposits were formed on the reactor wall during plasma pyrolysis of the Xinjiang candle coal in our V-style plasma pyrolysis pilot-plant. The carbon deposits were studied using a scanning electronic microscope (SEM) and the X-ray diffraction (XRD) method. It was found that carbon deposits located at different parts in the reactor exhibited different microscopic patterns. The formation mechanism of the carbon deposits was deduced. The downward increase in the graphitization degree of the carbon deposits was found and interpreted.

  7. Effect of plasma parameters on characteristics of silicon nitride film deposited by single and dual frequency plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Sahu, B. B.; Yin, Yongyi; Han, Jeon G.

    2016-03-01

    This work investigates the deposition of hydrogenated amorphous silicon nitride films using various low-temperature plasmas. Utilizing radio-frequency (RF, 13.56 MHz) and ultra-high frequency (UHF, 320 MHz) powers, different plasma enhanced chemical vapor deposition processes are conducted in the mixture of reactive N2/NH3/SiH4 gases. The processes are extensively characterized using different plasma diagnostic tools to study their plasma and radical generation capabilities. A typical transition of the electron energy distribution function from single- to bi-Maxwellian type is achieved by combining RF and ultra-high powers. Data analysis revealed that the RF/UHF dual frequency power enhances the plasma surface heating and produces hot electron population with relatively low electron temperature and high plasma density. Using various film analysis methods, we have investigated the role of plasma parameters on the compositional, structural, and optical properties of the deposited films to optimize the process conditions. The presented results show that the dual frequency power is effective for enhancing dissociation and ionization of neutrals, which in turn helps in enabling high deposition rate and improving film properties.

  8. Effect of plasma parameters on characteristics of silicon nitride film deposited by single and dual frequency plasma enhanced chemical vapor deposition

    SciTech Connect

    Sahu, B. B. E-mail: hanjg@skku.edu; Yin, Yongyi; Han, Jeon G. E-mail: hanjg@skku.edu

    2016-03-15

    This work investigates the deposition of hydrogenated amorphous silicon nitride films using various low-temperature plasmas. Utilizing radio-frequency (RF, 13.56 MHz) and ultra-high frequency (UHF, 320 MHz) powers, different plasma enhanced chemical vapor deposition processes are conducted in the mixture of reactive N{sub 2}/NH{sub 3}/SiH{sub 4} gases. The processes are extensively characterized using different plasma diagnostic tools to study their plasma and radical generation capabilities. A typical transition of the electron energy distribution function from single- to bi-Maxwellian type is achieved by combining RF and ultra-high powers. Data analysis revealed that the RF/UHF dual frequency power enhances the plasma surface heating and produces hot electron population with relatively low electron temperature and high plasma density. Using various film analysis methods, we have investigated the role of plasma parameters on the compositional, structural, and optical properties of the deposited films to optimize the process conditions. The presented results show that the dual frequency power is effective for enhancing dissociation and ionization of neutrals, which in turn helps in enabling high deposition rate and improving film properties.

  9. Plasma engineering of silicon quantum dots and their properties through energy deposition and chemistry.

    PubMed

    Sahu, Bibhuti Bhusan; Yin, Yongyi; Gauter, Sven; Han, Jeon Geon; Kersten, Holger

    2016-09-21

    The characterization of plasma and atomic radical parameters along with the energy influx from plasma to the substrate during plasma enhanced chemical vapor deposition (PECVD) of Si quantum dot (QD) films is presented and discussed. In particular, relating to the Si QD process optimization and control of film growth, the necessity to control the deposition environment by inducing the effect of the energy of the key plasma species is realized. In this contribution, we report dual frequency PECVD processes for the low-temperature and high-rate deposition of Si QDs by chemistry and energy control of the key plasma species. The dual frequency plasmas can effectively produce a very high plasma density and atomic H and N densities, which are found to be crucial for the growth and nucleation of QDs. Apart from the study of plasma chemistry, the crucial role of the energy imparted due to these plasma activated species on the substrate is determined in light of QD formation. Various plasma diagnostics and film analysis methods are integrated to correlate the effect of plasma and energy flux on the properties of the deposited films prepared in the reactive mixtures of SiH4/NH3 at various pressures. The present results are highly relevant to the development of the next-generation plasma process for devices that rely on effective control of the QD size and film properties.

  10. Optical emission study of a doped diamond deposition process by plasma enhanced chemical vapor deposition

    SciTech Connect

    Rayar, M.; Supiot, P.; Veis, P.; Gicquel, A.

    2008-08-01

    Standard H{sub 2}/CH{sub 4}/B{sub 2}H{sub 6} plasmas (99% of H{sub 2} and 1% of CH{sub 4}, with 0-100 ppm of B{sub 2}H{sub 6} added) used for doped diamond film growth are studied by optical emission spectroscopy in order to gain a better understanding of the influence of boron species on the gas phase chemistry. Only two boron species are detected under our experimental conditions (9/15/23 W cm{sup -3} average microwave power density values), and the emission spectra used for studies reported here are B({sup 2}S{sub 1/2}-{sup 2}P{sub 1/2,3/2}{sup 0}) and BH[A {sup 1}{pi}-X {sup 1}{sigma}{sup +}(0,0)]. Variations of their respective emission intensities as a function of the ratio B/C, the boron to carbon ratio in the gas mixture, are reported. We confirmed that the plasma parameters (T{sub g}, T{sub e}, and n{sub e}) are not affected by the introduction of diborane, and the number densities of B atoms and BH radical species were estimated from experimental measurements. The results are compared to those obtained from a zero-dimensional chemical kinetic model where two groups of reactions are considered: (1) BH{sub x}+H{r_reversible}BH{sub x-1}+H{sub 2} (x=1-3) by analogy with the well-known equilibrium CH{sub x}+H set of reactions, which occurs, in particular, in diamond deposition reactors; and (2) from conventional organic chemistry, the set of reactions involving boron species: BH{sub x}+C{sub 2}H{sub 2} (x=0-1). The results clearly show that the model based on hydrogen and boron hydrides reactions alone is not consistent with the experimental results, while it is so when taking into account both sets of reactions. Once an upper limit for the boron species number densities has been estimated, axial profiles are calculated on the basis of the plasma model results obtained previously in Laboratoire d'Ingenierie des Materiaux et des Hautes Pressions, and significant differences in trends for different boron species are found. At the plasma-to-substrate boundary

  11. Optical emission study of a doped diamond deposition process by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Rayar, M.; Supiot, P.; Veis, P.; Gicquel, A.

    2008-08-01

    Standard H2/CH4/B2H6 plasmas (99% of H2 and 1% of CH4, with 0-100ppm of B2H6 added) used for doped diamond film growth are studied by optical emission spectroscopy in order to gain a better understanding of the influence of boron species on the gas phase chemistry. Only two boron species are detected under our experimental conditions (9/15/23Wcm-3 average microwave power density values), and the emission spectra used for studies reported here are B(S1/22-P1/2,3/202) and BH [AΠ1-XΣ+1(0,0)]. Variations of their respective emission intensities as a function of the ratio B /C, the boron to carbon ratio in the gas mixture, are reported. We confirmed that the plasma parameters (Tg, Te, and ne) are not affected by the introduction of diborane, and the number densities of B atoms and BH radical species were estimated from experimental measurements. The results are compared to those obtained from a zero-dimensional chemical kinetic model where two groups of reactions are considered: (1) BHx+H ↔BHx -1+H2 (x=1-3) by analogy with the well-known equilibrium CHx+H set of reactions, which occurs, in particular, in diamond deposition reactors; and (2) from conventional organic chemistry, the set of reactions involving boron species: BHx+C2H2 (x =0-1). The results clearly show that the model based on hydrogen and boron hydrides reactions alone is not consistent with the experimental results, while it is so when taking into account both sets of reactions. Once an upper limit for the boron species number densities has been estimated, axial profiles are calculated on the basis of the plasma model results obtained previously in Laboratoire d'Ingénierie des Matériaux et des Hautes Pressions, and significant differences in trends for different boron species are found. At the plasma-to-substrate boundary, [BH] and [B] drop off in contrast to [BH2], which shows little decrease, and [BH3], which shows little increase, in this region.

  12. Influence of emitter temperature on the energy deposition in a low-pressure plasma

    SciTech Connect

    Levko, Dmitry; Raja, Laxminarayan L.

    2016-03-15

    The influence of emitter temperature on the energy deposition into low-pressure plasma is studied by the self-consistent one-dimensional Particle-in-Cell Monte Carlo Collisions model. Depending on the emitter temperature, different modes of discharge operation are obtained. The mode type depends on the plasma frequency and does not depend on the ratio between the densities of beam and plasma electrons. Namely, plasma is stable when the plasma frequency is small. For this plasma, the energy transfer from emitted electrons to plasma electrons is inefficient. The increase in the plasma frequency results first in the excitation of two-stream electron instability. However, since the thermal velocity of plasma electrons is smaller than the electrostatic wave velocity, the resonant wave-particle interaction is inefficient for the energy deposition into the plasma. Further increase in the plasma frequency leads to the distortion of beam of emitted electrons. Then, the electrostatic wave generated due to two-stream instability decays into multiple slower waves. Phase velocities of these waves are comparable with the thermal velocity of plasma electrons which makes possible the resonant wave-particle interaction. This results in the efficient energy deposition from emitted electrons into the plasma.

  13. Microstructure and characterization of a novel cobalt coating prepared by cathode plasma electrolytic deposition

    NASA Astrophysics Data System (ADS)

    Quan, Cheng; He, Yedong

    2015-10-01

    A novel cobalt coating was prepared by cathode plasma electrolytic deposition (CPED). The kinetics of the electrode process in cathode plasma electrolytic deposition was studied. The composition and microstructure of the deposited coatings were investigated by SEM, EDS, XRD and TEM. The novel cobalt coatings were dense and uniform, showing a typically molten morphology, and were deposited with a rather fast rate. Different from the coatings prepared by conventional electrodeposition or chemical plating, pure cobalt coatings with face center cubic (fcc) structure were obtained by CPED. The deposited coatings were nanocrystalline structure with an average grain size of 40-50 nm, exhibited high hardness, excellent adhesion with the stainless steels, and superior wear resistance. The properties of the novel cobalt coatings prepared by CPED have been improved significantly, as compared with that prepared by conventional methods. It reveals that cathode plasma electrolytic deposition is an effective way to prepare novel cobalt coatings with high quality.

  14. Experimental investigation on geometrical aspects of micro-plasma deposited tool steel for repair applications

    NASA Astrophysics Data System (ADS)

    Jhavar, S.; Paul, C. P.; Jain, N. K.

    2014-08-01

    Recent advancement in direct material deposition processes found wide applications in rapid prototyping, manufacturing and tooling industry. Micro-plasma deposition is one of the recent developments in this domain. This paper reports the deployment of newly integrated micro-plasma deposition system for the deposition of AISI P-20 tool steel on the AISI P20 tool steel substrate. A number of test tracks for single track deposition were deposited at the various combination of processing parameters. The sets of parameters yielding good deposits were selected to deposit overlap tracks. The geometry of single and overlapped tracks was evaluated to understand the parametric dependence. The study indicates that the aspect ratio of track geometry (ratio of width to height of track) is dependent on the processing parameters and the discharge current is identified as the most dominating parameters (contribution = 44%), followed by scan speed (contribution = 26.68%) and wire feed rate (contribution = 26.98%) with almost same effect. The microscopic study of the deposits indicates that the material deposited at the optimum processing parameters is free from surface and bulk defects. The estimated material properties are found to be at par with conventional processed material. This feasibility study proved that the micro-plasma deposition can be used for the generation of surfaces and multi-featured material deposition. It paved a way for the application of the process in die/mold repairs.

  15. Deposition of dielectric films on silicon using a fore-vacuum plasma electron source.

    PubMed

    Zolotukhin, D B; Oks, E M; Tyunkov, A V; Yushkov, Yu G

    2016-06-01

    We describe an experiment on the use of a fore-vacuum-pressure, plasma-cathode, electron beam source with current up to 100 mA and beam energy up to 15 keV for deposition of Mg and Al oxide films on Si substrates in an oxygen atmosphere at a pressure of 10 Pa. The metals (Al and Mg) were evaporated and ionized using the electron beam with the formation of a gas-metal beam-plasma. The plasma was deposited on the surface of Si substrates. The elemental composition of the deposited films was analyzed.

  16. Deposition of dielectric films on silicon using a fore-vacuum plasma electron source

    SciTech Connect

    Zolotukhin, D. B.; Tyunkov, A. V.; Yushkov, Yu. G.; Oks, E. M.

    2016-06-15

    We describe an experiment on the use of a fore-vacuum-pressure, plasma-cathode, electron beam source with current up to 100 mA and beam energy up to 15 keV for deposition of Mg and Al oxide films on Si substrates in an oxygen atmosphere at a pressure of 10 Pa. The metals (Al and Mg) were evaporated and ionized using the electron beam with the formation of a gas-metal beam-plasma. The plasma was deposited on the surface of Si substrates. The elemental composition of the deposited films was analyzed.

  17. High-rate diamond deposition by microwave plasma CVD

    NASA Astrophysics Data System (ADS)

    Li, Xianglin

    In this dissertation, the growth of CVD (Chemical Vapor Deposition) diamond thin films is studied both theoretically and experimentally. The goal of this research is to deposit high quality HOD (Highly Oriented Diamond) films with a growth rate greater than 1 mum/hr. For the (100)-oriented HOD films, the growth rate achieved by the traditional process is only 0.3 mum/hr while the theoretical limit is ˜0.45 mum/hr. This research increases the growth rate up to 5.3 mum/hr (with a theoretical limit of ˜7 mum/hr) while preserving the crystal quality. This work builds a connection between the theoretical study of the CVD process and the experimental research. The study is extended from the growth of regular polycrystalline diamond to highly oriented diamond (HOD) films. For the increase of the growth rate of regular polycrystalline diamond thin films, a scaling growth model developed by Goodwin is introduced in details to assist in the understanding of the MPCVD (Microwave Plasma CVD) process. Within the Goodwin's scaling model, there are only four important sub-processes for the growth of diamond: surface modification, adsorption, desorption, and incorporation. The factors determining the diamond growth rate and film quality are discussed following the description of the experimental setup and process parameters. Growth rate and crystal quality models are reviewed to predict and understand the experimental results. It is shown that the growth rate of diamond can be increased with methane input concentration and the amount of atomic hydrogen (by changing the total pressure). It is crucial to provide enough atomic hydrogen to conserve crystal quality of the deposited diamond film. The experimental results demonstrate that for a fixed methane concentration, there is a minimum pressure for growth of good diamond. Similarly, for a fixed total pressure, there is a maximum methane concentration for growth of good diamond, and this maximum methane concentration increases

  18. Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

    2017-09-01

    Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

  19. W and WC layers deposition by shielded inductively coupled plasma source

    NASA Astrophysics Data System (ADS)

    Colpo, P.; Meziani, T.; Sauvageot, P.; Ceccone, G.; Gibson, P. N.; Rossi, F.; Monge-Cadet, P.

    2002-09-01

    Tungsten and carbon tungsten films have been deposited by a plasma enhanced chemical vapor deposition (PECVD) technique. The plasma-assisted deposition was performed by inductively coupled plasma source (ICP). A Faraday shield was arranged within the plasma chamber to prevent electrically conductive film deposition on the dielectric chamber wall that would screen the electromagnetic field. External electrical parameters and ion densities of the shielded inductive plasma source are measured and compared to classical ICPs source characteristics. Tungsten deposition has been performed from WF6 diluted in argon and hydrogen. A deposition rate of 5 mum/h was obtained. Hardness measurements show that the tungsten hardness can be increased from 5 to 20 GPA by biasing the substrate. WC films were deposited by adding methane or acetylene to the WF6/H2 mixture. The hardness of the WC films depends strongly on the methane or acetylene flow rate, i.e., on the film carbon content. The WC hardness has been correlated to the crystallographic structure. The first hardness maximum peak corresponds to a solid solution of carbon in the tungsten. Correlation between the deposition parameters, such as the gas composition, dc bias and coating properties has been investigated by means of AES, XRD, and nanoindentation analysis. copyright 2002 American Vacuum Society.

  20. Effect of substrate temperature on deposition rate of rf plasma-deposited hydrogenated amorphous silicon thin films

    NASA Astrophysics Data System (ADS)

    Andújar, J. L.; Bertran, E.; Canillas, A.; Campmany, J.; Morenza, J. L.

    1991-03-01

    We present a study about the influence of substrate temperature on deposition rate of hydrogenated amorphous silicon thin films prepared by rf glow discharge decomposition of pure silane gas in a capacitively coupled plasma reactor. Two different behaviors are observed depending on deposition pressure conditions. At high pressure (30 Pa) the influence of substrate temperature on deposition rate is mainly through a modification of gas density, in such a way that the substrate temperature of deposition rate is similar to pressure dependence at constant temperature. On the contrary, at low pressure (3 Pa), a gas density effect cannot account for the observed increase of deposition rate as substrate temperature rises above 450 K with an activation energy of 1.1 kcal/mole. In accordance with laser-induced fluorescence measurements reported in the literature, this rise has been ascribed to an increase of secondary electron emission from the growing film surface as a result of molecular hydrogen desorption.

  1. Role of plasma enhanced atomic layer deposition reactor wall conditions on radical and ion substrate fluxes

    SciTech Connect

    Sowa, Mark J.

    2014-01-15

    Chamber wall conditions, such as wall temperature and film deposits, have long been known to influence plasma source performance on thin film processing equipment. Plasma physical characteristics depend on conductive/insulating properties of chamber walls. Radical fluxes depend on plasma characteristics as well as wall recombination rates, which can be wall material and temperature dependent. Variations in substrate delivery of plasma generated species (radicals, ions, etc.) impact the resulting etch or deposition process resulting in process drift. Plasma enhanced atomic layer deposition is known to depend strongly on substrate radical flux, but film properties can be influenced by other plasma generated phenomena, such as ion bombardment. In this paper, the chamber wall conditions on a plasma enhanced atomic layer deposition process are investigated. The downstream oxygen radical and ion fluxes from an inductively coupled plasma source are indirectly monitored in temperature controlled (25–190 °C) stainless steel and quartz reactors over a range of oxygen flow rates. Etch rates of a photoresist coated quartz crystal microbalance are used to study the oxygen radical flux dependence on reactor characteristics. Plasma density estimates from Langmuir probe ion saturation current measurements are used to study the ion flux dependence on reactor characteristics. Reactor temperature was not found to impact radical and ion fluxes substantially. Radical and ion fluxes were higher for quartz walls compared to stainless steel walls over all oxygen flow rates considered. The radical flux to ion flux ratio is likely to be a critical parameter for the deposition of consistent film properties. Reactor wall material, gas flow rate/pressure, and distance from the plasma source all impact the radical to ion flux ratio. These results indicate maintaining chamber wall conditions will be important for delivering consistent results from plasma enhanced atomic layer deposition

  2. Contamination due to memory effects in filtered vacuum arc plasma deposition systems

    SciTech Connect

    Martins, D.R.; Salvadori, M.C.; Verdonck, P.; Brown, I.G.

    2002-08-13

    Thin film synthesis by filtered vacuum arc plasma deposition is a widely used technique with a number of important emerging technological applications. A characteristic feature of the method is that during the deposition process not only is the substrate coated by the plasma, but the plasma gun itself and the magnetic field coil and/or vacuum vessel section constituting the macroparticle filter are also coated to some extent. If then the plasma gun cathode is changed to a new element, there can be a contamination of the subsequent film deposition by sputtering from various parts of the system of the previous coating species. We have experimentally explored this effect and compared our results with theoretical estimates of sputtering from the SRIM (Stopping and Range of Ions in Matter) code. We find film contamination of order 10-4 - 10-3, and the memory of the prior history of the deposition hardware can be relatively long-lasting.

  3. Low-pressure microwave plasma nucleation and deposition of diamond films

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.; Rich, D. H.

    1992-01-01

    Low-pressure microwave plasma nucleation and deposition of diamond films were investigated in the pressure range 10-mtorr to 10 torr, at substrate temperatures 400-750 C and with CH4 and O2 concentrations in H2 plasma of 2-15 percent and 2-10 percent, respectively. The experiments were performed in a microwave plasma system consisting of a microwave plasma chamber, a downstream deposition chamber, and an RF induction heated sample stage. Scanning electron microscopy of diamond films deposited at 600 C with 5 percent CH4 and 5 percent O2 in H2 plasmas showed high-quality well faceted crystallites of 1/2 micron size. Cathodoluminescence measurements of these films showed very few nitrogen impurities and no detectable silicon impurities.

  4. Low-pressure microwave plasma nucleation and deposition of diamond films

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.; Rich, D. H.

    1992-01-01

    Low-pressure microwave plasma nucleation and deposition of diamond films were investigated in the pressure range 10-mtorr to 10 torr, at substrate temperatures 400-750 C and with CH4 and O2 concentrations in H2 plasma of 2-15 percent and 2-10 percent, respectively. The experiments were performed in a microwave plasma system consisting of a microwave plasma chamber, a downstream deposition chamber, and an RF induction heated sample stage. Scanning electron microscopy of diamond films deposited at 600 C with 5 percent CH4 and 5 percent O2 in H2 plasmas showed high-quality well faceted crystallites of 1/2 micron size. Cathodoluminescence measurements of these films showed very few nitrogen impurities and no detectable silicon impurities.

  5. The Role of Plasma in Plasma Enhanced Chemical Vapour Deposition of Nanostructure Growth

    NASA Technical Reports Server (NTRS)

    Hash, David B.; Meyyappan, M.; Teo, Kenneth B. K.; Lacerda, Rodrigo G.; Rupesinghe, Nalin L.

    2004-01-01

    Chemical vapour deposition (CVD) has become the preferred process for high yield growth of carbon nanotubes and nanofibres because of its ability to pattern growth through lithographic positioning of transition metal catalysts on substrates. Many potential applications of nanotubes such as field emitters [1] require not only patterned growth but also vertical alignment. Some degree of ali,ment in thermal CVD processes can be obtained when carbon nanotubes are grown closely together as a result of van der Waals interactions. The ali,onment however is marginal, and the van der Waals prerequisite makes growth of freestanding nanofibres with thermal CVD unrealizable. The application of electric fields as a means of ali,onment has been shown to overcome this limitation [2-5], and highly aligned nanostructures can be grown if electric fields on the order of 0.5 V/microns are employed. Plasma enhanced CVD in various configurations including dc, rf, microwave, inductive and electron cyclotron resonance has been pursued as a means of enabling alignment in the CVD process. However, the sheath fields for the non-dc sources are in general not sufficient for a high degree of ali,pment and an additional dc bias is usually applied to the growth substrate. This begs the question as to the actual role of the plasma. It is clear that the plasma itself is not required for aligned growth as references [3] and [4] employed fields through small applied voltages (3-20 V) across very small electrode spacings (10-100 microns) and thus avoided striking a discharge.

  6. Method For Plasma Source Ion Implantation And Deposition For Cylindrical Surfaces

    DOEpatents

    Fetherston, Robert P. , Shamim, Muhammad M. , Conrad, John R.

    1997-12-02

    Uniform ion implantation and deposition onto cylindrical surfaces is achieved by placing a cylindrical electrode in coaxial and conformal relation to the target surface. For implantation and deposition of an inner bore surface the electrode is placed inside the target. For implantation and deposition on an outer cylindrical surface the electrode is placed around the outside of the target. A plasma is generated between the electrode and the target cylindrical surface. Applying a pulse of high voltage to the target causes ions from the plasma to be driven onto the cylindrical target surface. The plasma contained in the space between the target and the electrode is uniform, resulting in a uniform implantation or deposition of the target surface. Since the plasma is largely contained in the space between the target and the electrode, contamination of the vacuum chamber enclosing the target and electrodes by inadvertent ion deposition is reduced. The coaxial alignment of the target and the electrode may be employed for the ion assisted deposition of sputtered metals onto the target, resulting in a uniform coating of the cylindrical target surface by the sputtered material. The independently generated and contained plasmas associated with each cylindrical target/electrode pair allows for effective batch processing of multiple cylindrical targets within a single vacuum chamber, resulting in both uniform implantation or deposition, and reduced contamination of one target by adjacent target/electrode pairs.

  7. Electrowetting on plasma-deposited fluorocarbon hydrophobic films for biofluid transport in microfluidics

    SciTech Connect

    Bayiati, P.; Tserepi, A.; Petrou, P. S.; Kakabakos, S. E.; Misiakos, K.; Gogolides, E.

    2007-05-15

    The present work focuses on the plasma deposition of fluorocarbon (FC) films on surfaces and the electrostatic control of their wettability (electrowetting). Such films can be employed for actuation of fluid transport in microfluidic devices, when deposited over patterned electrodes. Here, the deposition was performed using C{sub 4}F{sub 8} and the plasma parameters that permit the creation of films with optimized properties desirable for electrowetting were established. The wettability of the plasma-deposited surfaces was characterized by means of contact angle measurements (in the static and dynamic mode). The thickness of the deposited films was probed in situ by means of spectroscopic ellipsometry, while the surface roughness was provided by atomic force microscopy. These plasma-deposited FC films in combination with silicon nitride, a material of high dielectric constant, were used to create a dielectric structure that requires reduced voltages for successful electrowetting. Electrowetting experiments using protein solutions were conducted on such optimized dielectric structures and were compared with similar structures bearing commercial spin-coated Teflon registered amorphous fluoropolymer (AF) film as the hydrophobic top layer. Our results show that plasma-deposited FC films have desirable electrowetting behavior and minimal protein adsorption, a requirement for successful transport of biological solutions in 'digital' microfluidics.

  8. Study on effect of plasma surface treatments for diamond deposition by DC arc plasmatron.

    PubMed

    Kang, In-Je; Joa, Sang-Beom; Lee, Heon-Ju

    2013-11-01

    To improve the thermal conductivity and wear resistance of ceramic materials in the field of renewable energy technologies, diamond coating by plasma processing has been carried out in recent years. This study's goal is to improve diamond deposition on Al2O3 ceramic substrates by plasma surface treatments. Before diamond deposition was carried out in a vacuum, plasma surface treatments using Ar gas were conducted to improve conditions for deposition. We also conducted plasma processing for diamond deposition on Al2O3 ceramic substrates using a DC arc Plasmatron. The Al2O3 ceramic substrates with diamond film (5 x 15 mm2), were investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then, the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) was studied. We identified nanocrystalline diamond films on the Al2O3 ceramic substrates. The results showed us that the deposition rate of diamond films was 2.3 microm/h after plasma surface treatments. Comparing the above result with untreated ceramic substrates, the deposition rate improved with the surface roughness of the deposited diamond films.

  9. High power impulse magnetron sputtering and related discharges: scalable plasma sources for plasma-based ion implantation and deposition

    SciTech Connect

    Anders, Andre

    2009-09-01

    High power impulse magnetron sputtering (HIPIMS) and related self-sputtering techniques are reviewed from a viewpoint of plasma-based ion implantation and deposition (PBII&D). HIPIMS combines the classical, scalable sputtering technology with pulsed power, which is an elegant way of ionizing the sputtered atoms. Related approaches, such as sustained self-sputtering, are also considered. The resulting intense flux of ions to the substrate consists of a mixture of metal and gas ions when using a process gas, or of metal ions only when using `gasless? or pure self-sputtering. In many respects, processing with HIPIMS plasmas is similar to processing with filtered cathodic arc plasmas, though the former is easier to scale to large areas. Both ion implantation and etching (high bias voltage, without deposition) and thin film deposition (low bias, or bias of low duty cycle) have been demonstrated.

  10. Plasma-enhanced chemical vapor deposition of low-resistive tungsten thin films

    SciTech Connect

    Kim, Y.T.; Min, S.; Hong, J.S. ); Kim, C.K. )

    1991-02-25

    Controlling the wafer temperatures from 200 to 500 {degree}C at H{sub 2}/WF{sub 6} flow ratio equal to 24, low-resistive (about 11 {mu}{Omega} cm) tungsten thin films are deposited by plasma-enhanced chemical vapor deposition. The as-deposited tungsten films have (110), (200), and (211) oriented bcc structures and Auger depth profile shows that fluorine and oxygen impurities are below the detection limit of Auger electron spectroscopy.

  11. Plasma-enhanced atomic layer deposition: a gas-phase route to hydrophilic, glueable polytetrafluoroethylene.

    PubMed

    Roy, Amit K; Dendooven, Jolien; Deduytsche, Davy; Devloo-Casier, Kilian; Ragaert, Kim; Cardon, Ludwig; Detavernier, Christophe

    2015-02-28

    This communication reports an approach based on plasma-enhanced atomic layer deposition of aluminium oxide for the functionalization of polytetrafluoroethylene (PTFE or "Teflon") surfaces. Alternating exposure of PTFE to oxygen plasma and trimethylaluminium causes a permanent hydrophilic effect, and a more than 10-fold improvement of the "glueability" of PTFE to aluminium.

  12. Effects of the growth conditions on the roughness of amorphous hydrogenated carbon films deposited by plasma enhanced chemical vapor deposition

    SciTech Connect

    Capote, G.; Prioli, R.; Freire, F. L. Jr.

    2006-11-15

    The surface roughness and scaling behavior of a-C:H films deposited by plasma enhanced chemical vapor deposition from CH{sub 4}-Ar mixtures were studied using atomic force microscopy. Raman spectroscopy gives some insights about the film microstructure. The film surface roughness is shown to decrease with the increase of deposition negative self-bias, while the presence of Ar ions enhances this effect. An analysis of the film surface and scaling behavior suggests that there is a transition of the mechanism of the film growth from a random deposition with surface diffusion process to a thermal spike based process that occurs upon the increase of the negative self-bias voltage and the argon bombardment.

  13. Influence of the normalized ion flux on the constitution of alumina films deposited by plasma-assisted chemical vapor deposition

    SciTech Connect

    Kurapov, Denis; Reiss, Jennifer; Trinh, David H.; Hultman, Lars; Schneider, Jochen M.

    2007-07-15

    Alumina thin films were deposited onto tempered hot working steel substrates from an AlCl{sub 3}-O{sub 2}-Ar-H{sub 2} gas mixture by plasma-assisted chemical vapor deposition. The normalized ion flux was varied during deposition through changes in precursor content while keeping the cathode voltage and the total pressure constant. As the precursor content in the total gas mixture was increased from 0.8% to 5.8%, the deposition rate increased 12-fold, while the normalized ion flux decreased by approximately 90%. The constitution, morphology, impurity incorporation, and the elastic properties of the alumina thin films were found to depend on the normalized ion flux. These changes in structure, composition, and properties induced by normalized ion flux may be understood by considering mechanisms related to surface and bulk diffusion.

  14. Plasma-enhanced atomic layer deposition of silicon dioxide films using plasma-activated triisopropylsilane as a precursor

    SciTech Connect

    Jeon, Ki-Moon; Shin, Jae-Su; Yun, Ju-Young; Jun Lee, Sang; Kang, Sang-Woo

    2014-05-15

    The plasma-enhanced atomic layer deposition (PEALD) process was developed as a growth technique of SiO{sub 2} thin films using a plasma-activated triisopropylsilane [TIPS, ((iPr){sub 3}SiH)] precursor. TIPS was activated by an argon plasma at the precursor injection stage of the process. Using the activated TIPS, it was possible to control the growth rate per cycle of the deposited films by adjusting the plasma ignition time. The PEALD technique allowed deposition of SiO{sub 2} films at temperatures as low as 50 °C without carbon impurities. In addition, films obtained with plasma ignition times of 3 s and 10 s had similar values of root-mean-square surface roughness. In order to evaluate the suitability of TIPS as a precursor for low-temperature deposition of SiO{sub 2} films, the vapor pressure of TIPS was measured. The thermal stability and the reactivity of the gas-phase TIPS with respect to water vapor were also investigated by analyzing the intensity changes of the C–H and Si–H peaks in the Fourier-transform infrared spectrum of TIPS.

  15. Plasma properties of a new-type surface wave-sustained plasma source under the conditions of depositing DLC films

    NASA Astrophysics Data System (ADS)

    Xu, Junqi; Kousaka, Hiroyuki; Umehara, Noritsugu; Diao, Dongfeng

    2006-01-01

    Surface wave-sustained plasma (SWP) is one of the low-pressure, high- density plasma. Applying this technique, diamond-like carbon (DLC) films with excellent characteristics can be prepared by physical vapor deposition (PVD) method. However, the films' application is restricted in some degree, because it is difficult to control the film properties. In this paper, SWP was excited along a conductive rod at a frequency of 2.45 GHz without magnetic fields around the chamber wall. The fundamental theories of plasma diagnostic were presented and plasma properties were studied with a Langmuir probe under the conditions of depositing DLC films by PVD method with a graphite target. Plasma density, electron temperature, plasma potential and target current were measured at difference technique parameters such as gas pressure, microwave power, and so on. As a result, it was proved that plasma properties are greatly affected by microwave power, target voltage and argon gas pressure in chamber. The gas mass flow rate had almost no effect on plasma characters. At the same time, the results indicated that electron density is up to 10 11-10 12cm -3 even at the low pressure of 1 Pa.

  16. Compositional study of silicon oxynitride thin films deposited using electron cyclotron resonance plasma-enhanced chemical vapor deposition technique

    SciTech Connect

    Baumann, H.; Sah, R.E.

    2005-05-01

    We have used backscattering spectrometry and {sup 15}N({sup 1}H,{alpha},{gamma}){sup 12}C nuclear reaction analysis techniques to study in detail the variation in the composition of silicon oxynitride films with deposition parameters. The films were deposited using 2.45 GHz electron cyclotron resonance plasma-enhanced chemical vapor deposition (PECVD) technique from mixtures of precursors argon, nitrous oxide, and silane at deposition temperature 90 deg. C. The deposition pressure and nitrous oxide-to-silane gas flow rates ratio have been found to have a pronounced influence on the composition of the films. When the deposition pressure was varied for a given nitrous oxide-to-silane gas flow ratio, the amount of silicon and nitrogen increased with the deposition pressure, while the amount of oxygen decreased. For a given deposition pressure, the amount of incorporated nitrogen and hydrogen decreased while that of oxygen increased with increasing nitrous oxide-to-silane gas flow rates ratio. For nitrous oxide-to-silane gas flow ratio of 5, we obtained films which contained neither chemically bonded nor nonbonded nitrogen atoms as revealed by the results of infrared spectroscopy, backscattering spectrometry, and nuclear reaction analysis. Our results demonstrate the nitrogen-free nearly stoichiometric silicon dioxide films can be prepared from a mixture of precursors argon, nitrous oxide, and silane at low substrate temperature using high-density PECVD technique. This avoids the use of a hazardous and an often forbidden pair of silane and oxygen gases in a plasma reactor.

  17. Low-temperature SiON films deposited by plasma-enhanced atomic layer deposition method using activated silicon precursor

    SciTech Connect

    Suh, Sungin; Kim, Jun-Rae; Kim, Seongkyung; Hwang, Cheol Seong; Kim, Hyeong Joon; Ryu, Seung Wook; Cho, Seongjae

    2016-01-15

    It has not been an easy task to deposit SiN at low temperature by conventional plasma-enhanced atomic layer deposition (PE-ALD) since Si organic precursors generally have high activation energy for adsorption of the Si atoms on the Si-N networks. In this work, in order to achieve successful deposition of SiN film at low temperature, the plasma processing steps in the PE-ALD have been modified for easier activation of Si precursors. In this modification, the efficiency of chemisorption of Si precursor has been improved by additional plasma steps after purging of the Si precursor. As the result, the SiN films prepared by the modified PE-ALD processes demonstrated higher purity of Si and N atoms with unwanted impurities such as C and O having below 10 at. % and Si-rich films could be formed consequently. Also, a very high step coverage ratio of 97% was obtained. Furthermore, the process-optimized SiN film showed a permissible charge-trapping capability with a wide memory window of 3.1 V when a capacitor structure was fabricated and measured with an insertion of the SiN film as the charge-trap layer. The modified PE-ALD process using the activated Si precursor would be one of the most practical and promising solutions for SiN deposition with lower thermal budget and higher cost-effectiveness.

  18. Plasma-deposited amorphous hydrogenated carbon films and their tribological properties

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Pouch, John J.; Alterovitz, Samuel A.

    1989-01-01

    Recent work on the properties of diamondlike carbon films and their dependence on preparation conditions are reviewed. The results of the study indicate that plasma deposition enables one to deposit a variety of amorphous hydrogenated carbon (a-C:H ) films exhibiting more diamondlike behavior to more graphitic behavior. The plasma-deposited a-C:H can be effectively used as hard, wear-resistant, and protective lubricating films on ceramic materials such as Si(sub 3)N(sub 4) under a variety of environmental conditions such as moist air, dry nitrogrn, and vacuum.

  19. Control of interface nanoscale structure created by plasma-enhanced chemical vapor deposition.

    PubMed

    Peri, Someswara R; Akgun, Bulent; Satija, Sushil K; Jiang, Hao; Enlow, Jesse; Bunning, Timothy J; Foster, Mark D

    2011-09-01

    Tailoring the structure of films deposited by plasma-enhanced chemical vapor deposition (PECVD) to specific applications requires a depth-resolved understanding of how the interface structures in such films are impacted by variations in deposition parameters such as feed position and plasma power. Analysis of complementary X-ray and neutron reflectivity (XR, NR) data provide a rich picture of changes in structure with feed position and plasma power, with those changes resolved on the nanoscale. For plasma-polymerized octafluorocyclobutane (PP-OFCB) films, a region of distinct chemical composition and lower cross-link density is found at the substrate interface for the range of processing conditions studied and a surface layer of lower cross-link density also appears when plasma power exceeds 40 W. Varying the distance of the feed from the plasma impacts the degree of cross-linking in the film center, thickness of the surface layer, and thickness of the transition region at the substrate. Deposition at the highest power, 65 W, both enhances cross-linking and creates loose fragments with fluorine content higher than the average. The thickness of the low cross-link density region at the air interface plays an important role in determining the width of the interface built with a layer subsequently deposited atop the first.

  20. Niobium thin film coating on a 500-MHz copper cavity by plasma deposition

    SciTech Connect

    Haipeng Wang; Genfa Wu; H. Phillips; Robert Rimmer; Anne-Marie Valente; Andy Wu

    2005-05-16

    A system using an Electron Cyclotron Resonance (ECR) plasma source for the deposition of a thin niobium film inside a copper cavity for superconducting accelerator applications has been designed and is being constructed. The system uses a 500-MHz copper cavity as both substrate and vacuum chamber. The ECR plasma will be created to produce direct niobium ion deposition. The central cylindrical grid is DC biased to control the deposition energy. This paper describes the design of several subcomponents including the vacuum chamber, RF supply, biasing grid and magnet coils. Operational parameters are compared between an operating sample deposition system and this system. Engineering work progress toward the first plasma creation will be reported here.

  1. The effect of bias voltage on the morphology and wettability of plasma deposited titanium oxide films

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Li, Yan; Guo, Kai; Zhang, Jing

    2008-02-01

    Hydrophobic and hydrophilic films with titanium oxide inside were grown by radio frequency plasma enhanced chemical vapor deposition (RF--PECVD) on glass substrates. Bias voltage was used as an assistant for the deposition process. And a comparison was made between with and without the bias voltage. Titanium tetraisopropoxide (TTIP-Ti (OC 3H 7) 4) was used as the precursor compound. Film wettability was tested by water contact angle measurement (CAM). The water contact angle (WAC) of the film deposited in plasma without biased voltage was greater than 145°, while the WAC of the film deposited in plasma with biased voltage was less than 30°. The morphology of the deposited films was observed by scanning electron microscope (SEM). It is found that the films grown without bias voltage were covered with lots of nano grain and pores, but the surface of the films deposition with bias voltage was much dense. The chemical structure and property of the deposited films were analyzed by Fourier-transformed infrared spectroscopy (FTIR), while the plasma phase was investigated by optical emission spectroscopy (OES).

  2. Deposition of Hard Chrome Coating onto Heat Susceptible Substrates by Low Power Microwave Plasma Spray

    NASA Astrophysics Data System (ADS)

    Redza, Ahmad; Yasui, Toshiaki; Fukumoto, Masahiro

    2016-02-01

    Microwave plasma spray requires relatively low power, which is lower than 1 kW in comparison to other plasma spraying method. Until now, we are able to deposit Cu and Hydroxyapatite coating onto heat susceptible substrate, CFRP which are difficult for conventional plasma spray due to the excessive heat input. In this paper, a hard chromium coating was deposited onto SUS304 and CFRP by a low power microwave plasma spray technique. By controlling the working gas flow rate and spraying distance, a hard chrome coating with thickness of approximately 30 μm was successfully deposited onto CFRP substrate with hardness of 1110 Hv0.05. Furthermore, the coating produced here is higher than that produced by hard chrome plating.

  3. Studies of Discharge Parameters Influence on the IPD Plasma Deposition Process

    SciTech Connect

    Rabinski, Marek; Zdunek, Krzysztof

    2006-01-15

    The paper presents recent studies of a current sheet dynamics influence on the surface engineering process of impulse plasma deposition (IPD). During the IPD process plasma is generated in the working gas due to a high-voltage high-current oscillating pulse discharge, ignited within an interelectrode region of a coaxial accelerator. The changes of plasma dynamics and generation mechanisms, e.g. the electric arc instead of the plasma sheet formation during the consecutive half-periods of discharge, cause the different deposition efficiency for accelerator with the outer electrode system composed of stainless steel rods instead of standard tubular one. The coating efficiency and deposited layer quality have been examined for the titanium nitride as the model material for surface engineering.

  4. Carbon nanofiber growth in plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Denysenko, I.; Ostrikov, K.; Cvelbar, U.; Mozetic, M.; Azarenkov, N. A.

    2008-10-01

    A theoretical model to describe the plasma-assisted growth of carbon nanofibers (CNFs) is proposed. Using the model, the plasma-related effects on the nanofiber growth parameters, such as the growth rate due to surface and bulk diffusion, the effective carbon flux to the catalyst surface, the characteristic residence time and diffusion length of carbon atoms on the catalyst surface, and the surface coverages, have been studied. The dependence of these parameters on the catalyst surface temperature and ion and etching gas fluxes to the catalyst surface is quantified. The optimum conditions under which a low-temperature plasma environment can benefit the CNF growth are formulated. These results are in good agreement with the available experimental data on CNF growth and can be used for optimizing synthesis of related nanoassemblies in low-temperature plasma-assisted nanofabrication.

  5. The non-anticoagulant heparin-like K5 polysaccharide derivative K5-N,OSepi attenuates myocardial ischaemia/reperfusion injury

    PubMed Central

    Collino, Massimo; Pini, Alessandro; Mastroianni, Rosanna; Benetti, Elisa; Lanzi, Cecilia; Bani, Daniele; Chini, Jacopo; Manoni, Marco; Fantozzi, Roberto; Masini, Emanuela

    2012-01-01

    Heparin and low molecular weight heparins have been demonstrated to reduce myocardial ischaemia/reperfusion (I/R) injury, although their use is hampered by the risk of haemorrhagic and thrombotic complications. Chemical and enzymatic modifications of K5 polysaccharide have shown the possibility of producing heparin-like compounds with low anticoagulant activity and strong anti-inflammatory effects. Using a rat model of regional myocardial I/R, we investigated the effects of an epimerized N-,O-sulphated K5 polysaccharide derivative, K5-N,OSepi, on infarct size and histological signs of myocardial injury caused by 30 min. ligature of the left anterior descending coronary artery followed by 1 or 24 h reperfusion. K5-N,OSepi (0.1–1 mg/kg given i.v. 15 min. before reperfusion) significantly reduced the extent of myocardial damage in a dose-dependent manner. Furthermore, we investigated the potential mechanism(s) of the cardioprotective effect(s) afforded by K5-N,OSepi. In left ventricular samples, I/R induced mast cell degranulation and a robust increase in lipid peroxidation, free radical-induced DNA damage and calcium overload. Markers of neutrophil infiltration and activation were also induced by I/R in rat hearts, specifically myeloperoxidase activity, intercellular-adhesion-molecule-1 expression, prostaglandin-E2 and tumour-necrosis-factor-α production. The robust increase in oxidative stress and inflammatory markers was blunted by K5-N,OSepi, in a dose-dependent manner, with maximum at 1 mg/kg. Furthermore, K5-N,OSepi administration attenuated the increase in caspase 3 activity, Bid and Bax activation and ameliorated the decrease in expression of Bcl-2 within the ischaemic myocardium. In conclusion, we demonstrate that the cardioprotective effect of the non-anticoagulant K5 derivative K5-N,OSepi is secondary to a combination of anti-apoptotic and anti-inflammatory effects. PMID:22248092

  6. Spectroscopic characterization of the plasmas formed during the deposition of ZnO and Al-doped ZnO films by plasma-assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Liang, Peipei; Cai, Hua; Yang, Xu; Li, Hui; Zhang, Wu; Xu, Ning; Sun, Jian; Wu, Jiada

    2016-11-01

    An oxygen-zinc plasma and an oxygen-zinc-aluminum plasma are formed by pulsed laser ablation of a Zn target or pulsed laser co-ablation of a Zn target and an Al target in an electron cyclotron resonance (ECR) discharge-generated oxygen plasma for the deposition of ZnO and Al-doped ZnO (AZO) films. The plasmas are characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy. Both the oxygen-zinc plasma and the oxygen-zinc-aluminum plasma contain excited species originally present in the working O2 gas and energetic species ablated from the targets. The optical emission of the oxygen-zinc-aluminum plasma is abundant in the emission bands of oxygen molecular ions and the emission lines of mono-atomic oxygen, zinc and aluminum atoms and atomic ions. The time-integrated spectra as well as the time-resolved spectra of the plasma emission indicate that the oxygen species in the ECR oxygen plasma experience additional excitation by the expanding ablation plumes, and the ablated species are excited frequently when traveling accompanying the plume expansion in the oxygen plasma, making the formed plasma highly excited and very reactive, which plays an important role in the reactive growth of ZnO matrix and the in-situ doping of Al into the growing ZnO matrix. The deposited ZnO and AZO films were evaluated for composition analysis by energy dispersive X-ray spectroscopy, structure characterization by X-ray diffraction and optical transmission measurement. The deposited ZnO is slightly rich in O. The Al concentration of the AZO films can be controlled and varied simply by changing the repetition rate of the laser used for Al target ablation. Both the ZnO and the AZO films are featured with hexagonal wurtzite crystal structure and exhibit high optical transparency in a wide spectral region. Al doping results in an improvement in the ultraviolet transparency, a blue shift in the absorption edge and a widening of the band gap.

  7. Numerical simulation of the transient multiphase field during plasma deposition manufacturing composite materials

    NASA Astrophysics Data System (ADS)

    Kong, Fanrong; Zhang, Haiou; Wang, Guilan

    2009-04-01

    A solid/liquid/gas unified model has been developed to investigate the gradient composition formation during the plasma deposition manufacturing (PDM) composite materials process. In this model, an enthalpy porosity model was applied to deal with the melting and solidification of the deposited layer, and a level-set approach was introduced to track the evolution of the free surface of the molten pool and the deposited layer. Moreover, complicated physical phenomena occurring at the liquid/gas interface, including forced convection heat loss, heat emission and plasma heat source, have been incorporated into the governing equations by source terms. In this study, the numerical experiment of nickel base alloy powder deposited on the medium steel substrate by PDM technique was implemented based on the staggered grid and SIMPLEC algorithm. Concentration gradient distribution of the solute material at the composite material interface, fluid flow and temperature distribution in the molten pool and the deposited layer have been investigated in detail.

  8. Optical properties of silicon nitride films formed by plasma-chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Vlasukova, L. A.; Komarov, F. F.; Parkhomenko, I. N.; Milchanin, O. V.; Leont'ev, A. V.; Mudryi, A. V.; Togambaeva, A. K.

    2013-03-01

    The optical properties and structure of layers of silicon nitride deposited on silicon substrates by plasma-aided chemical vapor deposition at 300°C are studied by ellipsometry, Raman scattering, IR spectroscopy, and photoluminescence techniques. It is found that immediately after deposition the silicon nitride contains hydrogen in the form of Si-H bonds. Annealing (1100°C, 30 min) leads to dehydrogenation and densification of the nitride layer. An intense Si3N4 photoluminescence signal is detected in the green. Immediately after deposition the photoluminescence peak appears at 542 nm and annealing shifts it to shorter wavelengths.

  9. Properties of HfLaO MOS capacitor deposited on SOI with plasma enhanced atomic layer deposition

    SciTech Connect

    Wan, Wenyan; Cheng, Xinhong Cao, Duo; Zheng, Li; Xu, Dawei; Wang, Zhongjian; Xia, Chao; Shen, Lingyan; Yu, Yuehui; Shen, DaShen

    2014-01-15

    Amorphous HfLaO dielectric film was successfully deposited on a silicon-on-insulator (SOI) substrate by plasma enhanced atomic layer deposition with in situ plasma treatment. The HfLaO film retained its insulating characteristics and is thermally stable even after annealing at 800 °C. The film has a dielectric constant of 27.3 and leakage of only 0.03 mA/cm{sup 2} at a gate bias of |Vg − V{sub fb}| = 1 V. The capacitance equivalent oxide thickness is 0.7 nm. A new parallel electrode testing structure was applied to measure C–V and J–V characteristics for the SOI samples. This testing method for metal–oxide–semiconductor capacitors has potential uses for measuring other layered substrates.

  10. ZnO thin film deposition using colliding plasma plumes and single plasma plume: Structural and optical properties

    SciTech Connect

    Gupta, Shyam L. Thareja, Raj K.

    2013-12-14

    We report the comparative study on synthesis of thin films of ZnO on glass substrates using IR laser ablated colliding plasma plumes and conventional pulsed laser deposition using 355 nm in oxygen ambient. The optical properties of deposited films are characterized using optical transmission in the UV-visible range of spectrum and photoluminescence measurements. X-ray diffraction and atomic force microscopy are used to investigate the surface morphology of synthesized ZnO films. The films synthesized using colliding plumes created with 1064 nm are non-polar a-plane ZnO with transmission in UV-visible (300–800 nm) region ∼60% compared to polycrystalline thin film deposited using single plume which has chunk deposition and poor optical response. However, deposition with 355 nm single plume shows polar c-axis oriented thin film with average roughness (∼thickness) of ∼86 nm (∼850 nm) compared to ∼2 nm (∼3 μm) for 1064 nm colliding plumes. These observed differences in the quality and properties of thin films are attributed to the flux of mono-energetic plasma species with almost uniform kinetic energy and higher thermal velocity reaching the substrate from interaction/stagnation zone of colliding plasma plumes.

  11. Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings

    NASA Technical Reports Server (NTRS)

    Harder, Bryan J.; Zhu, Dongming

    2011-01-01

    In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (< 10 microns) single layers to be deposited and multilayer coatings of less than 100 microns to be generated with the flexibility to tailor microstructures by changing processing conditions. Coatings of yttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coated superalloy substrates using the PS-PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

  12. Deposition of polymeric perfluored thin films in proton ionic membranes by plasma processes

    NASA Astrophysics Data System (ADS)

    Polak, Peter Lubomir; Mousinho, Ana Paula; Ordonez, Nelson; da Silva Zambom, Luis; Mansano, Ronaldo Domingues

    2007-10-01

    In this work the surfaces of polymeric membranes based on Nafion (proton conducting material), used in proton exchange membranes fuel cells (PEMFC) had been modified by plasma deposition of perfluored polymers, in order to improve its functioning in systems of energy generation (fuel cells). The deposition increases the chemical resistance of the proton ionic polymers without losing the electrical properties. The processing of the membranes also reduces the permeability of the membranes to the alcohols (methanol and ethanol), thus preventing poisoning of the fuel cell. The processing of the membranes of Nafion was carried through in a system of plasma deposition using a mixture of CF 4 and H 2 gases. The plasma processing was made mainly to increase the chemical resistance and result in hydrophobic surfaces. The Fourier transformed infrared (FTIR) technique supplies a spectrum with information about the CF n bond formation. Through the Rutherford back scattering (RBS) technique it was possible to verify the deposition rate of the polymeric layer. The plasma process with composition of 60% of CF 4 and 40% of H 2 presented the best deposition rate. By the spectrum analysis for the optimized configuration, it was possible to verify that the film deposition occurred with a thickness of 90 nm, and fluorine concentration was nearly 30%. Voltammetry made possible to verify that the fluorination increases the membranes chemical resistance, improving the stability of Nafion, becoming an attractive process for construction of fuel cells.

  13. Effects of post-deposition argon implantation on the memory properties of plasma-deposited silicon nitride films

    NASA Astrophysics Data System (ADS)

    Shams, Q. A.; Brown, W. D.

    1989-10-01

    Post-deposition ion implantation has been used to introduce argon into plasma-enhanced chemically vapor deposited silicon nitride films in an attempt to influence the transfer, trapping, and emission of charge during write/erase exercising of the metal-silicon nitride-silicon oxide-silicon structure. Argon was implanted into the SiH4 -NH3 -N2 deposited films at energies ranging from 25 to 75 keV, current densities ranging from 0.1 to 75 μA/cm2 and fluences ranging from 1×1012 to 1×1016 ions/cm2. Physical properties of the films were studied by ellipsometry and infrared spectroscopy, while high frequency capacitance-voltage (C-V) curves were used to obtain programming, retention, and endurance characteristics.

  14. Effects of the wall boundary conditions of a showerhead plasma reactor on the uniformity control of RF plasma deposition

    NASA Astrophysics Data System (ADS)

    Kim, Ho Jun; Lee, Hae June

    2017-08-01

    Technical difficulties hinder the formation of uniform deposition profiles near the electrode edge during a deposition in a showerhead capacitively coupled plasma (CCP) reactor. The discharge structure, gas flow, and radial distribution of the source gas outward from the electrode edge are subject to change significantly, which in turn affects the spatial distributions of the radical fluxes toward the electrode. To control the local non-uniformity of deposition profiles in the SiH4/NH3/N2/He CCP discharges for a hydrogenated silicon nitride (SiNxHy) film, the effects of the reactor components―including the sidewall boundary condition, electrode spacing, and showerhead design―were investigated using an axisymmetric fluid model. When the sidewall is electrically grounded, the deposition rate profiles of the SiNxHy film remain consistently convex (in which the deposition rate at the reactor center is locally much higher than that near the electrode edge), regardless of electrode spacing. However, when the sidewall surface is dielectric, the deposition rate profile can be transformed between a convex and a concave shape (in which the deposition rate at the reactor center is locally much lower than that near the electrode edge) by varying electrode spacing. The showerhead design also enables the modification of edge deposition profiles by redistribution of the local depletion rate of radicals. The simulation results agree very well with the experimental measurement.

  15. Characteristics of Single-Track and Multi-track Depositions of Stellite by Micro-plasma Transferred Arc Powder Deposition Process

    NASA Astrophysics Data System (ADS)

    Sawant, Mayur S.; Jain, N. K.

    2017-08-01

    This paper describes the characteristics study of single-track and multi-track deposition of Stellite 6 on AISI 4130 steel substrate by indigenously developed micro-plasma transferred arc powder deposition (μ-PTAPD) process. Deposition height and width, dilution and microstructure have been used to characterize the single-track depositions by studying effects of micro-plasma power, travel speed of worktable and powder mass flow rate on energy consumption per unit traverse length and power consumption per unit powder mass flow rate. Micro-plasma power was found to be the most influential parameter that affects energy and deposition material consumption. Consequently, its influence on micro-hardness and abrasion resistance of multi-track deposition was studied. Results showed that increase in micro-plasma power decreases micro-hardness and scratch hardness number and increases mean value of friction coefficient. Comparison of microstructure and chemical composition of single-track and multi-track depositions revealed that single-track has finer dendritic microstructure than the multi-track deposition. The black colored matrix and white colored dendrites present in the multi-track deposition have higher wt.% of cobalt and less wt.% of chromium than the single-track deposition. Comparison of µ-PTAPD process capabilities with the existing processes for Stellite deposition establishes that it is an energy-efficient, cost-effective and good quality deposition yielding process.

  16. Plasma-Enhanced Chemical Vapor Deposition as a Method for the Deposition of Peptide Nanotubes

    DTIC Science & Technology

    2013-09-17

    45432, United States Distribution A: Approved for public release; distribution is unlimited. 2    Introduction: The unique ability of dipeptides ...Using physical vapor deposition (PVD) well-ordered assemblies of peptide nanotubes (PNTs) composed of dipeptide subunits are obtained on various...the PECVD deposition chamber with sublimation capability in the laboratory of Dr. Rajesh Naik (AFRL/RXAS) and conditions were modified for dipeptide

  17. Transport and Deposition of Hydrocarbons in the Plasma Generator PSI-2

    NASA Astrophysics Data System (ADS)

    Naujoks, D.; Bohmeyer, W.; Markin, A.; Arkhipov, I.; Carl, P.; Koch, B.; Reiner, H.-D.; Schröder, D.; Fussmann, G.

    A series of experiments dedicated to the analysis of transport and sticking of hydrocarbon molecules have been performed in the plasma generator PSI-2. As a source of hydrocarbons defined amounts of CH4 and C2H4 have been injected. After injection the molecules undergo a series of ionisation and dissociation reactions. The thickness change of deposited layers on temperature controlled collector surfaces (outside the plasma column) was measured in-situ by means of an optical spectroscopy for different plasma conditions (density, working gas, injection position) and as function of the collector temperature. It was found that the flux of atomic hydrogen mainly determines whether net-deposition or net-erosion occurs. For the simulation of the experiments the 3D Monte Carlo code ERO was applied allowing a numerical description of the emission, transport, deposition and re-erosion cycle of hydrocarbon molecules.

  18. Plasma exposure behavior of re-deposited tungsten on structural materials of fusion reactors

    NASA Astrophysics Data System (ADS)

    Xu, Yu-Ping; Wang, Jing; Zhou, Hai-Shan; Liu, Feng; Li, Zeng-De; Li, Xiao-Chun; Lu, Tao; Liu, Hao-Dong; Ding, Fang; Mao, Hong-Min; Zhao, Ming-Zhong; Lin, Chen-Guang; Luo, Guang-Nan

    2017-05-01

    To evaluate the effects of re-deposited tungsten (W) on the surface modification and hydrogen isotope retention behavior of fusion structural materials, the plasma exposure behavior of re-deposited W samples prepared by magnetron sputtering on the F82H steel, the V-5Cr-5Ti alloy as well as bare substrate samples was investigated. All the samples were exposed to 367 shots of deuterium plasmas in the 2015 spring EAST campaign. After the plasma exposure, large area of W layer was exfoliated, while big blisters were found at the interface between the remaining W layer and the substrate materials. The deuterium retention behavior of the samples with re-deposited W layer was characterized by thermal desorption spectroscopy and compared with the bare substrate samples.

  19. Interaction of platelets, fibrinogen and endothelial cells with plasma deposited PEO-like films

    NASA Astrophysics Data System (ADS)

    Yang, Zhilu; Wang, Jin; Li, Xin; Tu, Qiufen; Sun, Hong; Huang, Nan

    2012-02-01

    For blood-contacting biomedical implants like retrievable vena cava filters, surface-based diagnostic devices or in vivo sensors, limiting thrombosis and cell adhesion is paramount, due to a decrease even failure in performance. Plasma deposited PEO-like films were investigated as surface modifications. In this work, mixed gas composed of tetraethylene glycol dimethyl ether (tetraglyme) vapor and oxygen was used as precursor. It was revealed that plasma polymerization under high ratio of oxygen/tetraglyme led to deposition of the films that had high content of ether groups. This kind of PEO-like films had good stability in phosphate buffer solution. In vitro hemocompatibility and endothelial cell (EC) adhesion revealed low platelet adhesion, platelet activation, fibrinogen adhesion, EC adhesion and proliferation on such plasma deposited PEO-like films. This made it a potential candidate for the applications in anti-fouling surfaces of blood-contacting biomedical devices.

  20. Radio-frequency oxygen-plasma-enhanced pulsed laser deposition of IGZO films

    NASA Astrophysics Data System (ADS)

    Chou, Chia-Man; Lai, Chih-Chang; Chang, Chih-Wei; Wen, Kai-Shin; Hsiao, Vincent K. S.

    2017-07-01

    We demonstrate the crystalline structures, optical transmittance, surface and cross-sectional morphologies, chemical compositions, and electrical properties of indium gallium zinc oxide (IGZO)-based thin films deposited on glass and silicon substrates through pulsed laser deposition (PLD) incorporated with radio-frequency (r.f.)-generated oxygen plasma. The plasma-enhanced pulsed laser deposition (PEPLD)-based IGZO thin films exhibited a c-axis-aligned crystalline (CAAC) structure, which was attributed to the increase in Zn-O under high oxygen vapor pressure (150 mTorr). High oxygen vapor pressure (150 mTorr) and low r.f. power (10 W) are the optimal deposition conditions for fabricating IGZO thin films with improved electrical properties.

  1. Induced carbon deposition by local hydrocarbon injection into detached divertor plasmas in JET

    NASA Astrophysics Data System (ADS)

    Jet Efda Contributors Airila, M. I.; Coad, J. P.; Brezinsek, S.; Belo, P.; Groth, M.; Kirschner, A.; Makkonen, T.; Stamp, M. F.; Strachan, J. D.; Widdowson, A. M.; Wiesen, S.

    2011-08-01

    During detachment experiments of JET in 2007 (Brezinsek et al., 2009 [1]), 1 × 1022 molecules of 12CD4 were injected at a rate of about 5 × 1020 s-1 into L-mode plasma. The injection was done at the outer strike point in the centre of the horizontal target, just before opening the machine. The deposited layers were analyzed for deuterium post mortem after the removal of tiles. The heaviest local D deposition density is found immediately upstream of the gas inlet, but downstream the deposition is found over a larger area. In total, 3.7 × 1020 deuterium atoms were found locally deposited; if the mean D/C in the deposits is 0.4, then about 10% of the injected carbon was locally deposited. Transport and local deposition of the injected carbon was modeled with the 3D Monte Carlo impurity transport code ERO (Kirschner et al., 2000 [2]). The plasma background was generated with the onion-skin solver of the DIVIMP code (Stangeby and Elder, 1992 [3]). Locally deposited fraction is reproduced with ERO but the distribution not satisfactorily. In particular the poloidal transport of carbon is several times weaker than measured.

  2. Chemically treated plasma Aβ is a potential blood-based biomarker for screening cerebral amyloid deposition.

    PubMed

    Park, Jong-Chan; Han, Sun-Ho; Cho, Hyun Jin; Byun, Min Soo; Yi, Dahyun; Choe, Young Min; Kang, Seokjo; Jung, Eun Sun; Won, Su Jin; Kim, Eun Hye; Kim, Yu Kyeong; Lee, Dong Young; Mook-Jung, Inhee

    2017-03-22

    Plasma β-amyloid (Aβ) is a potential candidate for an Alzheimer's disease (AD) biomarker because blood is an easily accessible bio-fluid, which can be collected routinely, and Aβ is one of the major hallmarks of AD pathogenesis in the brain. However, the association between plasma Aβ levels and AD diagnosis is still unclear due to the instability and inaccurate measurements of plasma Aβ levels in the blood of patients with AD. If a consistent value of plasma Aβ from the blood can be obtained, this might help determine whether plasma Aβ is a potential biomarker for AD diagnosis. We predicted the brain amyloid deposit by measuring the plasma Aβ levels. This cross-sectional study included 353 participants (215 cognitively normal, 79 with mild cognitive impairment, and 59 with AD dementia) who underwent Pittsburgh-compound B positron emission tomography (PiB-PET) scans. We treated a mixture of protease inhibitors and phosphatase inhibitors (MPP) and detected plasma Aβ42 and Aβ40 (MPP-Aβ42 and MPP-Aβ40) in a stable manner using xMAP technology. MPP-Aβ40 and MPP-Aβ42/40 (MPP-Aβs) were significantly different between subjects with positive amyloid deposition (PiB+) and those with negative amyloid deposition (PiB-) (P < 0.0001). Furthermore, MPP-Aβ40 (P < 0.0001, r = 0.23) and MPP-Aβ42/40 ratio (P < 0.0001, r = -0.23) showed significant correlation with global PiB deposition (standardized uptake value ratio). In addition, our integrated multivariable (MPP-Aβ42/40, gender, age, and apolipoprotein E genotypes) logistic regression model proposes a new standard for the prediction of cerebral amyloid deposition. MPP-Aβ might be one of the potential blood biomarkers for the prediction of PiB-PET positivity in the brain.

  3. Growing aluminum nitride films by Plasma-Enhanced Atomic Layer Deposition at low temperatures

    NASA Astrophysics Data System (ADS)

    Tarala, V. A.; Altakhov, A. S.; Martens, V. Ya; Lisitsyn, S. V.

    2015-11-01

    Aluminum nitride films have been grown by Plasma-Enhanced Atomic Layer Deposition method. It was found that at temperatures of 250 °C and 280 °C increase of the plasma exposure step duration over 6 s, as well as increase of reactor purge step duration over 1 s does not affect the growth rate, however, it affects the microstructure of the films. It was found that crystalline aluminum nitride films deposit with plasma exposure duration over 10 s and the reactor purging over 10 s. When the temperature drops the increase of reactor purge step duration and plasma exposure step duration over 20 s is required for crystalline AlN film growth.

  4. Characterisation of the TiO2 coatings deposited by plasma spraying

    NASA Astrophysics Data System (ADS)

    Benea, M. L.; Benea, L. P.

    2016-02-01

    Plasma spraying of materials such as ceramics and non-metals, which have high melting points, has become a well-established commercial process. Such coatings are increasingly used in aerospace, automobile, textile, medical, printing and electrical industries to impart proprieties such as corrosion resistance, thermal resistance, wear resistance, etc. One of the most important characteristics of thermal barrier coatings is the ability to undergo fast temperature changes without failing, the so called thermal shock resistance. The formation of residual stresses in plasma sprayed ceramic and metallic coatings is a very complex process. Several factors, such as substrate material, substrate thickness, physical properties of both the substrate and the coating material, deposition rate, relative velocity of the plasma torch, etc. determine the final residual stress state of the coating at room temperature. Our objective is to characterize the titanium oxide and aluminium oxide coatings deposited by plasma spraying in structural terms, the resistance to thermal shock and residual stresses.

  5. Plasma source ion implantation to increase the adhesion of subsequently deposited coatings

    SciTech Connect

    Wood, B.P.; Walter, K.C.; Taylor, T.N.

    1997-10-01

    In Plasma Source Ion Implantation (PSII) an object is placed in a plasma and pulse biased to a high negative potential, so as to implant the plasma ions into the surface of the object. Although ion implantation, by itself, can yield desirable surface modification, it is even more useful as a method of creating a functionally graded interface between the substrate material and a subsequently deposited coating, which may be produced by altering operating conditions on the same plasma source. Although this interfacial region is very thin - as little as 20 nm - it can greatly increase the adhesion of the deposited coatings. We present here a description of this process, and compare a simulation of the graded interface with an XPS depth profile of the interfacial region for erbium metal implanted into steel.

  6. RF-plasma vapor deposition of siloxane on paper. Part 1: Physical evolution of paper surface

    NASA Astrophysics Data System (ADS)

    Sahin, Halil Turgut

    2013-01-01

    An alternative, new approach to improve the hydrophobicity and barrier properties of paper was evaluated by radio-frequency (RF) plasma octamethylcyclotetrasiloxane (OMCTSO) vapor treatment. The interaction between OMCTSO and paper, causing the increased hydophobicity, is likely through covalent bonding. The deposited thin silicone-like polymeric layer from OMCTSO plasma treatment possessed desirable hydrophobic properties. The SEM micrographs showed uniformly distributed grainy particles with various shapes on the paper surface. Deposition of the silicone polymer-like layer with the plasma treatment affects the distribution of voids in the network structure and increases the barrier against water intake and air. The water absorptivity was reduced by 44% for the OMCTSO plasma treated sheet. The highest resistance to air flow was an approximately 41% lower air permeability than virgin paper.

  7. Temporally and Spatially Resolved Plasma Spectroscopy in Pulsed Laser Deposition of Ultra-Thin Boron Nitride Films (Postprint)

    DTIC Science & Technology

    2015-04-24

    in the plasma plume. Boron, being the lighter of the two species ( atomic weights: B¼ 10.81, N¼ 14.01), will escape the Knudsen layer of plasma plume...AFRL-RX-WP-JA-2016-0196 TEMPORALLY AND SPATIALLY RESOLVED PLASMA SPECTROSCOPY IN PULSED LASER DEPOSITION OF ULTRA-THIN BORON NITRIDE...AND SPATIALLY RESOLVED PLASMA SPECTROSCOPY IN PULSED LASER DEPOSITION OF ULTRA-THIN BORON NITRIDE FILMS (POSTPRINT) 5a. CONTRACT NUMBER FA8650

  8. Plasma-Enhanced Deposition of Silicon Nitride from SiH4-N2 Mixture

    NASA Astrophysics Data System (ADS)

    Katoh, Kazuhisa; Yasui, Masaru; Watanabe, Hideo

    1983-05-01

    Excellent silicon nitride films which can be used as the gate insulator of an a-Si FET are fabricated by RF glow-discharge of SiH4-N2-H2 gas mixtures. Resistivity of larger than 1× 1016 Ω\\cdotcm and breakdown strength of 6× 106 V/cm are realized. The optimum deposition conditions are evaluated and briefly discussed in connection with mechanisms of the plasma-enhanced deposition.

  9. Plasma and Laser-Enhanced Deposition of Powders and Thin Films.

    NASA Astrophysics Data System (ADS)

    David, Moses

    The objective of this thesis has been the development of novel plasma and laser based techniques for the deposition and characterization of thin films and nano-scale powders. The different energy sources utilized for excitation and break -down of reactive species prior to deposition include an RF plasma discharge, an excimer laser and a CO _2 laser. Nanometer-scale (10-20 nm) powders and thin films of aluminum nitride (AlN) have been successfully deposited in a glow discharge by reacting trimethylaluminum and ammonia. Macroquantities (~800 mg/hr) of powder have been collected at the centers of two vortices around which the reactant gases swirl. Powders of AlN have large surface areas (85 m^2/g) and are free from oxygen contamination. Diamond-like-carbon (DLC) films have been deposited from ternary mixtures of butadiene, argon and hydrogen. DLC films have been etched in O _2 and CF_4/O _2 plasmas. The etching behavior was correlated with the deposition feed gas composition by combining the etch rate, bias voltage during deposition and the deposition rate into a new non-dimensional number. Two new processes for depositing copper films have been developed. The first technique involves the hydrogen plasma reduction of copper formate films and the second technique involves the reactive excimer laser ablation of copper formate. Particle forming plasmas have been characterized by measuring the light scattering intensity during the deposition of silicon nitride from silane/ammonia plasmas. Both spatial variations and transients during the plasma start -up and shut-off steps have been measured. The ultraviolet (vacuum ultraviolet and extreme ultraviolet) reflectance characteristics of AlN, DLC and SiC thin films has been measured. AlN and SiC films exhibit a relatively high (~20-40%) reflectance in the different regions of the ultraviolet spectrum. An improved algorithm has been developed for estimating thin film parameters such as thickness, refractive index, band-gap, and

  10. Development of plasma assisted thermal vapor deposition technique for high-quality thin film

    NASA Astrophysics Data System (ADS)

    Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

    2016-12-01

    The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10-3 Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance <20 Ω sq-1 and a visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

  11. Development of plasma assisted thermal vapor deposition technique for high-quality thin film.

    PubMed

    Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

    2016-12-01

    The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10(-3) Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance <20 Ω sq(-1) and a visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

  12. Microwave engineering of plasma-assisted CVD reactors for diamond deposition.

    PubMed

    Silva, F; Hassouni, K; Bonnin, X; Gicquel, A

    2009-09-09

    The unique properties of CVD diamond make it a compelling choice for high power electronics. In order to achieve industrial use of CVD diamond, one must simultaneously obtain an excellent control of the film purity, very low defect content and a sufficiently rapid growth rate. Currently, only microwave plasma-assisted chemical vapour deposition (MPACVD) processes making use of resonant cavity systems provide enough atomic hydrogen to satisfy these requirements. We show in this paper that the use of high microwave power density (MWPD) plasmas is necessary to promote atomic hydrogen concentrations that are high enough to ensure the deposition of high purity diamond films at large growth rates. Moreover, the deposition of homogeneous films on large surfaces calls for the production of plasma with appropriate shapes and large volumes. The production of such plasmas needs generating a fairly high electric field over extended regions and requires a careful design of the MW coupling system, especially the cavity. As far as MW coupling efficiency is concerned, the presence of a plasma load represents a mismatching perturbation to the cavity. This perturbation is especially important at high MWPD where the reflected fraction of the input power may be quite high. This mismatch can lead to a pronounced heating of the reactor walls. It must therefore be taken into account from the very beginning of the reactor design. This requires the implementation of plasma modelling tools coupled to detailed electromagnetic simulations. This is discussed in section 3. We also briefly discuss the operating principles of the main commercial plasma reactors before introducing the reactor design methodology we have developed. Modelling results for a new generation of reactors developed at LIMHP, working at very high power density, will be presented. Lastly, we show that scaling up this type of reactor to lower frequencies (915 MHz) can result in high density plasmas allowing for fast and

  13. Aerosol-assisted plasma deposition of hydrophobic polycations makes surfaces highly antimicrobial.

    PubMed

    Liu, Harris; Kim, Yoojeong; Mello, Kerrianne; Lovaasen, John; Shah, Apoorva; Rice, Norman; Yim, Jacqueline H; Pappas, Daphne; Klibanov, Alexander M

    2014-02-01

    The currently used multistep chemical synthesis for making surfaces antimicrobial by attaching to them hydrophobic polycations is replaced herein by an aerosol-assisted plasma deposition procedure. To this end, N,N-hexyl,methyl-PEI (HMPEI) is directly plasma-coated onto a glass surface. The resultant immobilized HMPEI coating has been thoroughly characterized and shown to be robust, bactericidal against Escherichia coli, and virucidal against human influenza virus.

  14. Plasma-Arc Deposited Elemental Boron Film for use as a Durable Nonstick Coating

    DTIC Science & Technology

    2007-09-01

    COOKWARE BORON PLASMA ARCS MAGNETIC PROPERTIES FILTERED VACUUM CATHODIC ARC 19a. NAME OF RESPONSIBLE PERSON 16. SECURITY CLASSIFICATION OF: a... magnetic ducting system, which would filter out macroparticles (particle debris from the cathode) and expand the boron plasma to produce a uniform, debris...current. In addition to the high rate of material production, vacuum arc deposition also benefits from the fact that the output vapor is in a fully

  15. Silicon carbon alloy thin film depositions using electron cyclotron resonance microwave plasmas

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.

    1990-01-01

    Amorphous and microcrystalline silicon carbon films (a-SiC:H, micro-c-SiC:H) have been deposited using SiH4, CH4 and H2 mixed gas ECR (electron cyclotron resonance) plasmas. The optical bandgap of a-SiC:H films is not dependent on the hydrogen dilution in the ECR plasma. The deposition rate of a-SiC:H films is found to be strongly dependent on the ECR magnetic field and the hydrogen dilution. The hydrogen dilution effect on the deposition rate indicates that the etching in ECR hydrogen plasmas plays an important role in the deposition of a-SiC:H films. The optical constants n and k of ECR-deposited a-SiC:H films in the wavelength region of 0.4 to 1.0 micron are determined to be 2.03-1.90 and 0.04-0.00, respectively. The microstructures of ECR-deposited micro-c-SiC:H films are shown by X-ray diffraction and SEM (scanning electron microscopy) to be composed of 1000-A alpha-SiC microcrystallites and amorphous network structures.

  16. Silicon carbon alloy thin film depositions using electron cyclotron resonance microwave plasmas

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.

    1990-01-01

    Amorphous and microcrystalline silicon carbon films (a-SiC:H, micro-c-SiC:H) have been deposited using SiH4, CH4 and H2 mixed gas ECR (electron cyclotron resonance) plasmas. The optical bandgap of a-SiC:H films is not dependent on the hydrogen dilution in the ECR plasma. The deposition rate of a-SiC:H films is found to be strongly dependent on the ECR magnetic field and the hydrogen dilution. The hydrogen dilution effect on the deposition rate indicates that the etching in ECR hydrogen plasmas plays an important role in the deposition of a-SiC:H films. The optical constants n and k of ECR-deposited a-SiC:H films in the wavelength region of 0.4 to 1.0 micron are determined to be 2.03-1.90 and 0.04-0.00, respectively. The microstructures of ECR-deposited micro-c-SiC:H films are shown by X-ray diffraction and SEM (scanning electron microscopy) to be composed of 1000-A alpha-SiC microcrystallites and amorphous network structures.

  17. Scalability of plasma enhanced atomic layer deposited ruthenium films for interconnect applications

    SciTech Connect

    Swerts, J.; Armini, S.; Carbonell, L.; Delabie, A.; Franquet, A.; Mertens, S.; Popovici, M.; Schaekers, M.; Witters, T.; Toekei, Z.; Beyer, G.; Van Elshocht, S.; Gravey, V.; Cockburn, A.; Shah, K.; Aubuchon, J.

    2012-01-15

    Ru thin films were deposited by plasma enhanced atomic layer deposition using MethylCyclopentadienylPyrrolylRuthenium (MeCpPy)Ru and N{sub 2}/NH{sub 3} plasma. The growth characteristics have been studied on titanium nitride or tantalum nitride substrates of various thicknesses. On SiO{sub 2}, a large incubation period has been observed, which can be resolved by the use of a metal nitride layer of {approx} 0.8 nm. The growth characteristics of Ru layers deposited on ultra-thin metal nitride layers are similar to those on thick metal nitride substrates despite the fact that the metal nitride layers are not fully closed. Scaled Ru/metal nitride stacks were deposited in narrow lines down to 25 nm width. Thinning of the metal nitride does not impact the conformality of the Ru layer in the narrow lines. For the thinnest lines the Ru deposited on the side wall showed a more granular structure when compared to the bottom of the trench, which is attributed to the plasma directionality during the deposition process.

  18. Plasma plume dynamics in magnetically assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Haverkamp, J. D.; Bourham, M. A.; Du, S.; Narayan, J.

    2009-01-01

    The expansion of a laser produced plasma perpendicular to a magnetic field is studied with a quadruple Langmuir probe and a B-dot probe. In regions where the kinetic beta is less than one, we find plume deceleration and weak displacement of the magnetic field. As the plume expands into regions of weak magnetic field, plume deceleration stops and the displacement of the magnetic field is large. The diffusion time of the magnetic field lines was consistent with anomalously large resistivity driven by the presence of an instability. Electron temperatures are larger than in the field-free case due to Ohmic heating mediated by the anomalously large resistivity.

  19. Deposition kinetics and characterization of stable ionomers from hexamethyldisiloxane and methacrylic acid by plasma enhanced chemical vapor deposition

    SciTech Connect

    Urstöger, Georg; Resel, Roland; Coclite, Anna Maria; Koller, Georg

    2016-04-07

    A novel ionomer of hexamethyldisiloxane and methacrylic acid was synthesized by plasma enhanced chemical vapor deposition (PECVD). The PECVD process, being solventless, allows mixing of monomers with very different solubilities, and for polymers formed at high deposition rates and with high structural stability (due to the high number of cross-links and covalent bonding to the substrate) to be obtained. A kinetic study over a large set of parameters was run with the aim of determining the optimal conditions for high stability and proton conductivity of the polymer layer. Copolymers with good stability over 6 months' time in air and water were obtained, as demonstrated by ellipsometry, X-Ray reflectivity, and FT-IR spectroscopy. Stable coatings showed also proton conductivity as high as 1.1 ± 0.1 mS cm{sup −1}. Chemical analysis showed that due to the high molecular weight of the chosen precursors, it was possible to keep the plasma energy-input-per-mass low. This allowed limited precursor fragmentation and the functional groups of both monomers to be retained during the plasma polymerization.

  20. Microstructural modification of nc-Si/SiOx films during plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Zhang, X. W.

    2005-07-01

    Nanocrystalline-silicon embedded silicon oxide films are prepared by plasma-enhanced chemical vapor deposition (PECVD) at 300 °C without post-heat treatment. Measurements of XPS, IR, XRD, and HREM are performed. Microstructural modifications are found occurring throughout the film deposition. The silica network with a high oxide state is suggested to be formed directly under the abduction of the former deposited layer, rather than processing repeatedly from the original low-oxide state of silica. Nanocrystalline silicon particles with a size of 6-10 nm are embedded in the SiOx film matrix, indicating the potential application in Si-based optoelectronic integrity.

  1. Optical emission diagnostics of plasmas in chemical vapor deposition of single-crystal diamond

    DOE PAGES

    Hemawan, Kadek W.; Hemley, Russell J.

    2015-08-03

    Here, a key aspect of single crystal diamond growth via microwave plasma chemical vapor deposition is in-process control of the local plasma-substrate environment, that is, plasma gas phase concentrations of activated species at the plasma boundary layer near the substrate surface. Emission spectra of the plasma relative to the diamond substrate inside the microwave plasma reactor chamber have been analyzed via optical emission spectroscopy. The spectra of radical species such as CH, C2, and H (Balmer series) important for diamond growth were found to be more depndent on operating pressure than on microwave power. Plasma gas temperatures were calculated frommore » measurements of the C2 Swan band (d3Π → a3Π transition) system. The plasma gas temperature ranges from 2800 to 3400 K depending on the spatial location of the plasma ball, microwave power and operating pressure. Addition of Ar into CH4 + H2 plasma input gas mixture has little influence on the Hα, Hβ, and Hγ intensities and single-crystal diamond growth rates.« less

  2. Optical emission diagnostics of plasmas in chemical vapor deposition of single-crystal diamond

    SciTech Connect

    Hemawan, Kadek W.; Hemley, Russell J.

    2015-08-03

    Here, a key aspect of single crystal diamond growth via microwave plasma chemical vapor deposition is in-process control of the local plasma-substrate environment, that is, plasma gas phase concentrations of activated species at the plasma boundary layer near the substrate surface. Emission spectra of the plasma relative to the diamond substrate inside the microwave plasma reactor chamber have been analyzed via optical emission spectroscopy. The spectra of radical species such as CH, C2, and H (Balmer series) important for diamond growth were found to be more depndent on operating pressure than on microwave power. Plasma gas temperatures were calculated from measurements of the C2 Swan band (d3Π → a3Π transition) system. The plasma gas temperature ranges from 2800 to 3400 K depending on the spatial location of the plasma ball, microwave power and operating pressure. Addition of Ar into CH4 + H2 plasma input gas mixture has little influence on the Hα, Hβ, and Hγ intensities and single-crystal diamond growth rates.

  3. Plasma-based ion implantation and deposition: A review of physics,technology, and applications

    SciTech Connect

    Pelletier, Jacques; Anders, Andre

    2005-05-16

    After pioneering work in the 1980s, plasma-based ion implantation (PBII) and plasma-based ion implantation and deposition (PBIID) can now be considered mature technologies for surface modification and thin film deposition. This review starts by looking at the historical development and recalling the basic ideas of PBII. Advantages and disadvantages are compared to conventional ion beam implantation and physical vapor deposition for PBII and PBIID, respectively, followed by a summary of the physics of sheath dynamics, plasma and pulse specifications, plasma diagnostics, and process modeling. The review moves on to technology considerations for plasma sources and process reactors. PBII surface modification and PBIID coatings are applied in a wide range of situations. They include the by-now traditional tribological applications of reducing wear and corrosion through the formation of hard, tough, smooth, low-friction and chemically inert phases and coatings, e.g. for engine components. PBII has become viable for the formation of shallow junctions and other applications in microelectronics. More recently, the rapidly growing field of biomaterial synthesis makes used of PBII&D to produce surgical implants, bio- and blood-compatible surfaces and coatings, etc. With limitations, also non-conducting materials such as plastic sheets can be treated. The major interest in PBII processing originates from its flexibility in ion energy (from a few eV up to about 100 keV), and the capability to efficiently treat, or deposit on, large areas, and (within limits) to process non-flat, three-dimensional workpieces, including forming and modifying metastable phases and nanostructures. We use the acronym PBII&D when referring to both implantation and deposition, while PBIID implies that deposition is part of the process.

  4. Plasma Diagnostics For The Investigation of Silane Based Glow Discharge Deposition Processes

    NASA Astrophysics Data System (ADS)

    Mataras, Dimitrios

    2001-10-01

    In this work is presented the study of microcrystalline silicon PECVD process through highly diluted silane in hydrogen discharges. The investigation is performed by applying different non intrusive plasma diagnostics (electrical, optical, mass spectrometric and laser interferometric measurements). Each of these measurements is related to different plasma sub-processes (gas physics, plasma chemistry and plasma surface interaction) and compose a complete set, proper for the investigation of the effect of external discharge parameters on the deposition processes. In the specific case these plasma diagnostics are applied for prospecting the optimal experimental conditions from the ic-Si:H deposition rate point of view. Namely, the main characteristics of the effect of frequency, discharge geometry, power consumption and total gas pressure on the deposition process are presented successively. Special attention is given to the study of the frequency effect (13.56 MHz 50 MHz) indicating that the correct way to compare results of different driving frequency discharges is by maintaining constant the total power dissipation in the discharge. The important role of frequency in the achievement of high deposition rates and on the optimization of all other parameters is underlined. Finally, the proper combination of experimental conditions that result from the optimal choice of each of the above-mentioned discharge parameters and lead to high microcrystalline silicon deposition rates (7.5 Å/sec) is presented. The increase of silane dissociation rate towards neutral radicals (frequency effect), the contribution of highly sticking to the surface radicals (discharge geometry optimum) and the controlled production of higher radicals through secondary gas phase reactions (total gas pressure), are presented as prerequisites for the achievement of high deposition rates.

  5. Deposition of hybrid organic-inorganic composite coatings using an atmospheric plasma jet system.

    PubMed

    Dembele, Amidou; Rahman, Mahfujur; Reid, Ian; Twomey, Barry; MacElroy, J M Don; Dowling, Denis P

    2011-10-01

    The objective of this study is to investigate the influence of alcohol addition on the incorporation of metal oxide nanoparticles into nm thick siloxane coatings. Titanium oxide (TiO2) nanoparticles with diameters of 30-80 nm were incorporated into an atmospheric plasma deposited tetramethylorthosilicate (TMOS) siloxane coating. The TMOS/TiO2 coating was deposited using the atmospheric plasma jet system known as PlasmaStream. In this system the liquid precursor/nanoparticle mixture is nebulised into the plasma. It was observed that prior to being nebulised the TiO2 particles agglomerated and settled over time in the TMOS/TiO2 mixture. In order to obtain a more stable nanoparticle/TMOS suspension the addition of the alcohols methanol, octanol and pentanol to this mixture was investigated. The addition of each of these alcohols was found to stabilise the nanoparticle suspension. The effect of the alcohol was therefore assessed with respect to the properties of the deposited coatings. It was observed that coatings deposited from TMOS/TiO2, with and without the addition of methanol were broadly similar. In contrast the coatings deposited with octanol and pentanol addition to the TMOS/TiO2 mixture were significantly thicker, for a given set of deposition parameters and were also more homogeneous. This would indicate that the alcohol precursor was incorporated into the plasma polymerised siloxane. The incorporation of the organic functionality from the alcohols was confirmed from FTIR spectra of the coatings. The difference in behaviour with alcohol type is likely to be due to the lower boiling point of methanol (65 degrees C), which is lower than the maximum plasma temperature measured at the jet orifice (77 degrees C). This temperature is significantly lower than the 196 degrees C and 136 degrees C boiling points of octanol and pentanol respectively. The friction of the coatings was determined using the Pin-on-disc technique. The more organic coatings deposited with

  6. Energy deposition of heavy ions in the regime of strong beam-plasma correlations.

    PubMed

    Gericke, D O; Schlanges, M

    2003-03-01

    The energy loss of highly charged ions in dense plasmas is investigated. The applied model includes strong beam-plasma correlation via a quantum T-matrix treatment of the cross sections. Dynamic screening effects are modeled by using a Debye-like potential with a velocity dependent screening length that guarantees the known low and high beam velocity limits. It is shown that this phenomenological model is in good agreement with simulation data up to very high beam-plasma coupling. An analysis of the stopping process shows considerably longer ranges and a less localized energy deposition if strong coupling is treated properly.

  7. Effect of argon and hydrogen on deposition of silicon from tetrochlrosilane in cold plasmas

    NASA Technical Reports Server (NTRS)

    Manory, R. R.; d.

    1985-01-01

    The roles of Ar and H2 on the decomposition of SiCl4 in cold plasma were investigated by Langmuir probes and mass spectrometry. Decomposition of the reactant by Ar only has been found to be very slow. In presence of H2 in the plasma SiCl4 is decomposed by fast radical-molecule reactions which are further enhanced by Ar due to additional ion-molecule reactions in which more H radicals are produced. A model for the plasma-surface interactions during deposition of mu-Si in the Ar + H2 + SiCl4 system is presented.

  8. Energy deposition in parallel-plate plasma accelerators. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Dicapua, M. S.

    1971-01-01

    To appraise the ratio of energy deposition into kinetic and thermal modes in plasma accelerators, a parallel-plate plasma accelerator has been operated in the quasi-steady mode with current pulses in the range of 10 to 100 kilo-amperes (kA), durations of the order of one millisecond, and argon mass flows up to 100 grams/sec. From photographic observations, spectroscopic measurements of velocity and electron density, and pressure measurements with a fast-rise piezoelectric transducer it is found that, for currents between 50 and 90 kA, the accelerated argon plasma is supersonic with ion velocities of 5 to 6 kilometers/sec.

  9. Formation of Iron Carbide Nanorod by Pulsed Plasma Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Yooyen, S.; Kawamura, T.; Kotake, S.; Suzuki, Y.

    2010-11-01

    Iron carbide nanorods were produced on the surface of pure iron sheet by means of pulsed plasma chemical vapor deposition. Hydrogen plasma was used in the initial state, varied from 10 to 60 minute, for the purpose of cleaning and preparing nanoparticles. The formation was done under methane atmosphere, varied from 2 to 30 minute. X-ray diffraction (XRD) patterns analysis showed that iron carbide was found on all of these experiment conditions. By field emission scanning electron micro spectroscopy (FESEM) observation, iron carbide nanorods, however, were found neatly only on the methane plasma treating at 10 minute.

  10. Rapid Deposition of Titanium Oxide and Zinc Oxide Films by Solution Precursor Plasma Spray

    NASA Astrophysics Data System (ADS)

    Ando, Yasutaka

    In order to develop a high rate atmospheric film deposition process for functional films, as a basic study, deposition of titanium oxide film and zinc oxide film by solution precursor plasma spray (SPPS) was conducted in open air. Consequently, in the case of titanium oxide film deposition, anantase film and amorphous film as well as rutile film could be deposited by varying the deposition distance. In the case of anatase dominant film, photo-catalytic properties of the films could be confirmed by wettability test. In addition, the dye sensitized sollar cell (DSC) using the TiO2 film deposited by this SPPS technique as photo voltaic device generates 49mV in OCV. On the other hand, in the case of zinc oxide film deposition, it was proved that well crystallized ZnO films with photo catalytic properties could be deposited. From these results, this process was found to have high potential for high rate functional film deposition process conducted in the air.

  11. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber.

    PubMed

    Dechana, A; Thamboon, P; Boonyawan, D

    2014-10-01

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al2O3 layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al2O3 films-analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques-will be discussed.

  12. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber

    SciTech Connect

    Dechana, A.; Thamboon, P.; Boonyawan, D.

    2014-10-15

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al{sub 2}O{sub 3} layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al{sub 2}O{sub 3} films—analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques—will be discussed.

  13. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber

    NASA Astrophysics Data System (ADS)

    Dechana, A.; Thamboon, P.; Boonyawan, D.

    2014-10-01

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al2O3 layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al2O3 films—analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques—will be discussed.

  14. From plasma immersion ion implantation to deposition: A historical perspective on principles and trends

    SciTech Connect

    Anders, Andre

    2001-06-14

    Plasma immersion techniques of surface modification are known under a myriad of names. The family of techniques reaches from pure plasma ion implantation, to ion implantation and deposition hybrid modes, to modes that are essentially plasma film deposition with substrate bias. In the most general sense, all plasma immersion techniques have in common that the surface of a substrate (target) is exposed to plasma and that relatively high substrate bias is applied. The bias is usually pulsed. In this review, the roots of immersion techniques are explored, some going back to the 1800s, followed by a discussion of the groundbreaking works of Adler and Conrad in the 1980s. In the 1990s, plasma immersion techniques matured in theoretical understanding, scaling, and the range of applications. First commercial facilities are now operational. Various immersion concepts are compiled and explained in this review. While gas (often nitrogen) ion implantation dominated the early years, film-forming immersion techniques and semiconductor processing gained importance. In the 1980s and 1990s we have seen exponential growth of the field but signs of slowdown are clear since 1998. Nevertheless, plasma immersion techniques have found, and will continue to have, an important place among surface modification techniques.

  15. Photocatalytic property of titanium dioxide thin films deposited by radio frequency magnetron sputtering in argon and water vapour plasma

    NASA Astrophysics Data System (ADS)

    Sirghi, L.; Hatanaka, Y.; Sakaguchi, K.

    2015-10-01

    The present work is investigating the photocatalytic activity of TiO2 thin films deposited by radiofrequency magnetron sputtering of a pure TiO2 target in Ar and Ar/H2O (pressure ratio 40/3) plasmas. Optical absorption, structure, surface morphology and chemical structure of the deposited films were comparatively studied. The films were amorphous and included a large amount of hydroxyl groups (about 5% of oxygen atoms were bounded to hydrogen) irrespective of the intentional content of water in the deposition chamber. Incorporation of hydroxyl groups in the film deposited in pure Ar plasma is explained as contamination of the working gas with water molecules desorbed by plasma from the deposition chamber walls. However, intentional input of water vapour into the discharge chamber decreased the deposition speed and roughness of the deposited films. The good photocatalytic activity of the deposited films could be attributed hydroxyl groups in their structures.

  16. Characterization of bismuth nanospheres deposited by plasma focus device

    SciTech Connect

    Ahmad, M.; Al-Hawat, Sh.; Akel, M.; Mrad, O.

    2015-02-14

    A new method for producing thin layer of bismuth nanospheres based on the use of low energy plasma focus device is demonstrated. Various techniques such as scanning electron microscopy, Rutherford backscattering spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy have been used to characterize the morphology and the composition of the nanospheres. Experimental parameters may be adjusted to favour the formation of bismuth nanospheres instead of microspheres. Therefore, the formation of large surface of homogeneous layer of bismuth nanospheres with sizes of below 100 nm can be obtained. The natural snowball phenomenon is observed to be reproduced in nanoscale where spheres roll over the small nanospheres and grow up to bigger sizes that can reach micro dimensions. The comet-like structure, a reverse phenomenon to snowball is also observed.

  17. BN coatings deposition by magnetron sputtering of B and BN targets in electron beam generated plasma

    NASA Astrophysics Data System (ADS)

    Kamenetskikh, A. S.; Gavrilov, N. V.; Koryakova, O. V.; Cholakh, S. O.

    2017-05-01

    Boron nitride coatings were deposited by reactive pulsed magnetron sputtering of B and BN targets (50 kHz, 10 µs for B; 13.56 MHz for BN) at 2-20 mA/cm2 ion current density on the substrate. The effect of electron beam generated plasma on characteristics of magnetron discharge and phase composition of coatings was studied.

  18. Plasma deposition of silver nanoparticles on ultrafiltration membranes: antibacterial and anti-biofouling properties.

    PubMed

    Cruz, Mercedes Cecilia; Ruano, Gustavo; Wolf, Marcus; Hecker, Dominic; Vidaurre, Elza Castro; Schmittgens, Ralph; Rajal, Verónica Beatriz

    2015-02-01

    A novel and versatile plasma reactor was used to modify Polyethersulphone commercial membranes. The equipment was applied to: i) functionalize the membranes with low-temperature plasmas, ii) deposit a film of poly(methyl methacrylate) (PMMA) by Plasma Enhanced Chemical Vapor Deposition (PECVD) and, iii) deposit silver nanoparticles (SNP) by Gas Flow Sputtering. Each modification process was performed in the same reactor consecutively, without exposure of the membranes to atmospheric air. Scanning electron microscopy and transmission electron microscopy were used to characterize the particles and modified membranes. SNP are evenly distributed on the membrane surface. Particle fixation and transport inside membranes were assessed before- and after-washing assays by X-ray photoelectron spectroscopy depth profiling analysis. PMMA addition improved SNP fixation. Plasma-treated membranes showed higher hydrophilicity. Anti-biofouling activity was successfully achieved against Gram-positive (Enterococcus faecalis) and -negative (Salmonella Typhimurium) bacteria. Therefore, disinfection by ultrafiltration showed substantial resistance to biofouling. The post-synthesis functionalization process developed provides a more efficient fabrication route for anti-biofouling and anti-bacterial membranes used in the water treatment field. To the best of our knowledge, this is the first report of a gas phase condensation process combined with a PECVD procedure in order to deposit SNP on commercial membranes to inhibit biofouling formation.

  19. Plasma deposition of silver nanoparticles on ultrafiltration membranes: antibacterial and anti-biofouling properties

    PubMed Central

    Cruz, Mercedes Cecilia; Ruano, Gustavo; Wolf, Marcus; Hecker, Dominic; Vidaurre, Elza Castro; Schmittgens, Ralph; Rajal, Verónica Beatriz

    2015-01-01

    A novel and versatile plasma reactor was used to modify Polyethersulphone commercial membranes. The equipment was applied to: i) functionalize the membranes with low-temperature plasmas, ii) deposit a film of poly(methyl methacrylate) (PMMA) by Plasma Enhanced Chemical Vapor Deposition (PECVD) and, iii) deposit silver nanoparticles (SNP) by Gas Flow Sputtering. Each modification process was performed in the same reactor consecutively, without exposure of the membranes to atmospheric air. Scanning electron microscopy and transmission electron microscopy were used to characterize the particles and modified membranes. SNP are evenly distributed on the membrane surface. Particle fixation and transport inside membranes were assessed before- and after-washing assays by X-ray photoelectron spectroscopy depth profiling analysis. PMMA addition improved SNP fixation. Plasma-treated membranes showed higher hydrophilicity. Anti-biofouling activity was successfully achieved against Gram-positive (Enterococcus faecalis) and -negative (Salmonella Typhimurium) bacteria. Therefore, disinfection by ultrafiltration showed substantial resistance to biofouling. The post-synthesis functionalization process developed provides a more efficient fabrication route for anti-biofouling and anti-bacterial membranes used in the water treatment field. To the best of our knowledge, this is the first report of a gas phase condensation process combined with a PECVD procedure in order to deposit SNP on commercial membranes to inhibit biofouling formation. PMID:26166926

  20. Passivation layer on polyimide deposited by combined plasma immersion ion implantation and deposition and cathodic vacuum arc technique

    SciTech Connect

    Han, Z. J.; Tay, B. K.; Sze, J. Y.; Ha, P. C. T.

    2007-05-15

    A thin passivation layer of aluminum oxide was deposited on polyimide by using the combined plasma immersion ion implantation and deposition (PIII and D) and cathodic vacuum arc technique. X-ray photoelectron spectroscopy C 1s spectra showed that the carbonyl bond (C=O) and ether group (C-O-C and C-N-C) presented in pristine polyimide were damaged by implantation of aluminum ions and deposition of an aluminum oxide passivation layer. O 1s and Al 2p spectra confirmed the formation of a thin aluminum oxide passivation layer. This passivation layer can be implemented in aerospace engineering where polyimide may suffer degradation from fast atomic oxygen in the low-earth-orbit environment. To test the protection of this passivation layer to energetic oxygen ions, a plasma-enhanced chemical vapor deposition system was used to simulate the oxygen-ion irradiation, and the results showed that a higher weight occurred for passivated samples compared to pristine ones. X-ray diffraction showed that Al peaks were presented on the surface region, but no aluminum oxide peak was detected. The authors then concluded that Al clusters were formed in polyimide besides aluminum oxide, which was in an x-ray amorphous state. Furthermore, contact-angle measurements showed a reduced contact angle for passivated polyimide from a pristine value of 78 deg. to 20 deg. by using deionized water. Several discussions have been made on the surface chemical and structural property changes by using the combined PIII and D and cathodic vacuum arc technique.

  1. Plasma-assisted atomic layer deposition of conformal Pt films in high aspect ratio trenches

    NASA Astrophysics Data System (ADS)

    Erkens, I. J. M.; Verheijen, M. A.; Knoops, H. C. M.; Keuning, W.; Roozeboom, F.; Kessels, W. M. M.

    2017-02-01

    To date, conventional thermal atomic layer deposition (ALD) has been the method of choice to deposit high-quality Pt thin films grown typically from (MeCp)PtMe3 vapor and O2 gas at 300 °C. Plasma-assisted ALD of Pt using O2 plasma can offer several advantages over thermal ALD, such as faster nucleation and deposition at lower temperatures. In this work, it is demonstrated that plasma-assisted ALD at 300 °C also allows for the deposition of highly conformal Pt films in trenches with high aspect ratio ranging from 3 to 34. Scanning electron microscopy inspection revealed that the conformality of the deposited Pt films was 100% in trenches with aspect ratio (AR) up to 34. These results were corroborated by high-precision layer thickness measurements by transmission electron microscopy for trenches with an aspect ratio of 22. The role of the surface recombination of O-radicals and the contribution of thermal ALD reactions is discussed.

  2. Plasma-assisted atomic layer deposition of conformal Pt films in high aspect ratio trenches.

    PubMed

    Erkens, I J M; Verheijen, M A; Knoops, H C M; Keuning, W; Roozeboom, F; Kessels, W M M

    2017-02-07

    To date, conventional thermal atomic layer deposition (ALD) has been the method of choice to deposit high-quality Pt thin films grown typically from (MeCp)PtMe3 vapor and O2 gas at 300 °C. Plasma-assisted ALD of Pt using O2 plasma can offer several advantages over thermal ALD, such as faster nucleation and deposition at lower temperatures. In this work, it is demonstrated that plasma-assisted ALD at 300 °C also allows for the deposition of highly conformal Pt films in trenches with high aspect ratio ranging from 3 to 34. Scanning electron microscopy inspection revealed that the conformality of the deposited Pt films was 100% in trenches with aspect ratio (AR) up to 34. These results were corroborated by high-precision layer thickness measurements by transmission electron microscopy for trenches with an aspect ratio of 22. The role of the surface recombination of O-radicals and the contribution of thermal ALD reactions is discussed.

  3. Correlations between plasma variables and the deposition process of Si films from chlorosilanes in low pressure RF plasma of argon and hydrogen

    NASA Technical Reports Server (NTRS)

    Avni, R.; Carmi, U.; Grill, A.; Manory, R.; Grossman, E.

    1984-01-01

    The dissociation of chlorosilanes to silicon and its deposition on a solid substrate in a RF plasma of mixtures of argon and hydrogen were investigated as a function of the macrovariables of the plasma. The dissociation mechanism of chlorosilanes and HCl as well as the formation of Si in the plasma state were studied by sampling the plasma with a quadrupole mass spectrometer. Macrovariables such as pressure, net RF power input and locations in the plasma reactor strongly influence the kinetics of dissociation. The deposition process of microcrystalline silicon films and its chlorine contamination were correlated to the dissociation mechanism of chlorosilanes and HCl.

  4. Topographic, optical and chemical properties of zinc particle coatings deposited by means of atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Wallenhorst, L. M.; Loewenthal, L.; Avramidis, G.; Gerhard, C.; Militz, H.; Ohms, G.; Viöl, W.

    2017-07-01

    In this research, topographic, optical and chemical properties of zinc oxide layers deposited by a cold plasma-spray process were measured. Here, zinc micro particles were fed to the afterglow of a plasma spark discharge whereas the substrates were placed in a quite cold zone of the effluent plasma jet. In this vein, almost closed layers were realised on different samples. As ascertained by laser scanning and atomic force microscopic measurements the particle size of the basic layer is in the nanometre scale. Additionally, larger particles and agglomerates were found on its top. The results indicate a partial plasma-induced diminishment of the initial particles, most probably due to melting or vaporisation. It is further shown that the plasma gives rise to an increased oxidation of such particles as confirmed by X-ray photoelectron spectroscopy. Quantitative analysis of the resulting mixed layer was performed. It is shown that the deposited layers consist of zinc oxide and elemental zinc in approximately equal shares. In addition, the layer's band gap energy was determined by spectroscopic analysis. Here, considerable UV blocking properties of the deposited layers were observed. Possible underlying effects as well as potential applications are presented.

  5. Atomic Layer Deposition of Silicon Nitride from Bis(tert-butylamino)silane and N2 Plasma.

    PubMed

    Knoops, Harm C M; Braeken, Eline M J; de Peuter, Koen; Potts, Stephen E; Haukka, Suvi; Pore, Viljami; Kessels, Wilhelmus M M

    2015-09-09

    Atomic layer deposition (ALD) of silicon nitride (SiNx) is deemed essential for a variety of applications in nanoelectronics, such as gate spacer layers in transistors. In this work an ALD process using bis(tert-butylamino)silane (BTBAS) and N2 plasma was developed and studied. The process exhibited a wide temperature window starting from room temperature up to 500 °C. The material properties and wet-etch rates were investigated as a function of plasma exposure time, plasma pressure, and substrate table temperature. Table temperatures of 300-500 °C yielded a high material quality and a composition close to Si3N4 was obtained at 500 °C (N/Si=1.4±0.1, mass density=2.9±0.1 g/cm3, refractive index=1.96±0.03). Low wet-etch rates of ∼1 nm/min were obtained for films deposited at table temperatures of 400 °C and higher, similar to that achieved in the literature using low-pressure chemical vapor deposition of SiNx at >700 °C. For novel applications requiring significantly lower temperatures, the temperature window from room temperature to 200 °C can be a solution, where relatively high material quality was obtained when operating at low plasma pressures or long plasma exposure times.

  6. Oxygen-Plasma-Treated Indium-Tin-Oxide Films on Nonalkali Glass Deposited by Super Density Arc Plasma Ion Plating

    NASA Astrophysics Data System (ADS)

    Kim, Soo Young; Hong, Kihyon; Son, Jun Ho; Jung, Gwan Ho; Lee, Jong-Lam; Choi, Kyu Han; Song, Kyu Ho; Ahn, Kyung Chul

    2008-02-01

    The effects of O2 plasma treatment on both the chemical composition and work function of an indium-tin-oxide (ITO) film were investigated. ITO films were deposited on non-alkali glass substrate by super density arc plasma ion plating for application in active-matrix organic light-emitting diodes (OLEDs). The water contact angle decreased from 38 to 11° as the ITO films were treated with O2 plasma for 60 s at a plasma power of 150 W, indicating an increase in the hydrophilicity of the surface. It was found that there were no distinct changes in the microstructure or electrical properties of the ITO films with O2 plasma treatment. Synchrotron radiation photoemission spectroscopy data revealed that O2 plasma treatment decreased the amount of carbon contamination and increased the number of unscreened states of In3+ and (O2)2- peroxo species. This played the role of increasing the work function of the ITO films by 1.7 eV. As a result, the turn-on voltage of the OLED decreased markedly from 24 to 8 V and the maximum luminance value of the OLED increased to 2500 cd/m2.

  7. Optical emission diagnostics of plasmas in chemical vapor deposition of single-crystal diamond

    SciTech Connect

    Hemawan, Kadek W. Hemley, Russell J.

    2015-11-15

    A key aspect of single crystal diamond growth via microwave plasma chemical vapor deposition is in-process control of the local plasma–substrate environment, that is, plasma gas phase concentrations of activated species at the plasma boundary layer near the substrate surface. Emission spectra of the plasma relative to the diamond substrate inside the microwave plasma reactor chamber have been analyzed via optical emission spectroscopy. The spectra of radical species such as CH, C{sub 2}, and H (Balmer series) important for diamond growth were identified and analyzed. The emission intensities of these electronically excited species were found to be more dependent on operating pressure than on microwave power. Plasma gas temperatures were calculated from measurements of the C{sub 2} Swan band (d{sup 3}Π → a{sup 3}Π transition) system. The plasma gas temperature ranges from 2800 to 3400 K depending on the spatial location of the plasma ball, microwave power and operating pressure. Addition of Ar into CH{sub 4}+H{sub 2} plasma input gas mixture has little influence on the Hα, Hβ, and Hγ intensities and single-crystal diamond growth rates.

  8. D majority heating in JET plasmas: ICRH modelling and experimental RF deposition

    SciTech Connect

    Lerche, E.; Eester, D. van; Lamalle, P.; Krasilnikov, A.

    2007-09-28

    Recent experiments in JET have provided information on the potential of using majority RF heating schemes in large plasmas. Adopting a wide range of available diagnostics, the plasma behaviour was monitored. The main results of the experiments are that--due to the poor antenna coupling at low frequency, the low (Ohmic) plasma temperature and the reduced RF electric field amplitude near the ion-cyclotron resonance layer of the majority ions--ICRH alone is barely capable of heating the plasma. On the other hand, when preheating the plasma using neutral beam injection, the wave-plasma coupling is noticeably improved and considerable plasma heating, followed by increased neutron yield were observed in several diagnostics. This effect is not only attributed to the lower collisionality of the pre-heated plasma but also to the Doppler-shifted IC absorption of the fast beam ions. By studying the response of the plasma to sudden changes in the RF power level, the experimental power deposition profiles were determined and compared to theoretical predictions. The numerical modelling was done adopting a coupled wave/Fokker-Planck code that enables accounting for the non-Maxwellian distributions of the RF heated particles and the injected beam ions in the wave equation, and for the actual local RF fields in the Fokker-Planck description. The theoretical results confirm the experimental finding that the beam ions do play a crucial role in this heating scheme.

  9. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

    2015-11-01

    Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C2, Ar, N2, CH, Hβ, and Hα were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T2g phonon at 1333 cm-1 peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit "coral" and "cauliflower-like" morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

  10. Surface and corrosion characteristics of carbon plasma implanted and deposited nickel-titanium alloy

    SciTech Connect

    Poon, R.W.Y.; Liu, X.Y.; Chung, C.Y.; Chu, P.K.; Yeung, K.W.K.; Lu, W.W.; Cheung, K.M.C.

    2005-05-01

    Nickel-titanium shape memory alloys (NiTi) are potentially useful in orthopedic implants on account of their super-elastic and shape memory properties. However, the materials are prone to surface corrosion and the most common problem is out-diffusion of harmful Ni ions from the substrate into body tissues and fluids. In order to improve the corrosion resistance and related surface properties, we used the technique of plasma immersion ion implantation and deposition to deposit an amorphous hydrogenated carbon coating onto NiTi and implant carbon into NiTi. Both the deposited amorphous carbon film and carbon plasma implanted samples exhibit much improved corrosion resistances and surface mechanical properties and possible mechanisms are suggested.

  11. Plasma-enhanced chemical vapor deposition of graphene on copper substrates

    SciTech Connect

    Woehrl, Nicolas Schulz, Stephan; Ochedowski, Oliver; Gottlieb, Steven; Shibasaki, Kosuke

    2014-04-15

    A plasma enhanced vapor deposition process is used to synthesize graphene from a hydrogen/methane gas mixture on copper samples. The graphene samples were transferred onto SiO{sub 2} substrates and characterized by Raman spectroscopic mapping and atomic force microscope topographical mapping. Analysis of the Raman bands shows that the deposited graphene is clearly SLG and that the sheets are deposited on large areas of several mm{sup 2}. The defect density in the graphene sheets is calculated using Raman measurements and the influence of the process pressure on the defect density is measured. Furthermore the origin of these defects is discussed with respect to the process parameters and hence the plasma environment.

  12. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    DOE PAGES

    Gou, Huiyang; Hemley, Russell J.; Hemawan, Kadek W.

    2015-11-02

    Polycrystalline diamond has been successfully synthesized on silicon substrates at atmospheric pressure using a microwave capillary plasma chemical vapor deposition technique. The CH4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C2, Ar, N2, CH, Hβ and Hα were observed in emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T2g phonon at 1333 cm-1 peak relative to the Raman features of graphitic carbon. Furthermore, field emission scanning electron microscopy (SEM) images revealmore » that, depending on the on growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.« less

  13. Formation of nanocrystalline diamond in polymer like carbon films deposited by plasma CVD.

    PubMed

    Bhaduri, A; Chaudhuri, P

    2009-09-01

    Conventional plasma enhanced chemical vapour deposition (PECVD) method is generally not suitable for the growth of nanocrystalline diamond (NCD) films. However, our study shows that conditions favourable for powder formation help to grow large amount of nanocrystallites in conventional PECVD. With CH4 as the carbon source gas, dilution with Ar and moderate (50 W) rf power enhances formations of powders (nanoparticles) and C2 dimers within the plasma. On the other hand, with pure CH4 or with hydrogen diluted CH4, powder formation as also NCD growth is hindered. It is proposed that the nanoparticles formed in the plasma act as the "islands" while the C2 dimers are the "seeds" for the NCD growth. The structure of the films deposited on the grounded anode under different conditions of dilution has been studied. It is observed that with high Ar dilution the films contain NCD embedded in polymer like carbon (PLC) matrix.

  14. Plasma-enhanced chemical vapor deposition of amorphous Si on graphene

    NASA Astrophysics Data System (ADS)

    Lupina, G.; Strobel, C.; Dabrowski, J.; Lippert, G.; Kitzmann, J.; Krause, H. M.; Wenger, Ch.; Lukosius, M.; Wolff, A.; Albert, M.; Bartha, J. W.

    2016-05-01

    Plasma-enhanced chemical vapor deposition of thin a-Si:H layers on transferred large area graphene is investigated. Radio frequency (RF, 13.56 MHz) and very high frequency (VHF, 140 MHz) plasma processes are compared. Both methods provide conformal coating of graphene with Si layers as thin as 20 nm without any additional seed layer. The RF plasma process results in amorphization of the graphene layer. In contrast, the VHF process keeps the high crystalline quality of the graphene layer almost intact. Correlation analysis of Raman 2D and G band positions indicates that Si deposition induces reduction of the initial doping in graphene and an increase of compressive strain. Upon rapid thermal annealing, the amorphous Si layer undergoes dehydrogenation and transformation into a polycrystalline film, whereby a high crystalline quality of graphene is preserved.

  15. Plasma-enhanced chemical vapor deposition method to coat micropipettes with diamond-like carbon

    SciTech Connect

    Kakuta, Naoto; Watanabe, Mayu; Yamada, Yukio; Okuyama, Naoki; Mabuchi, Kunihiko

    2005-07-15

    This article provides a simple method for coating glass micropipettes with diamond-like carbon (DLC) through plasma-enhanced chemical vapor deposition. The apparatus uses a cathode that is a thin-metal-coated micropipette itself and an anode that is a meshed cylinder with its cylinder axis along the micropipette length. To produce a uniform plasma and prevent a temperature increase at the tip due to ion collision concentration, we investigated the effect of the height and diameter of the meshed cylindrical anode on the plasma. Intermittent deposition is also effective for inhibiting the temperature rise and producing high quality DLC films. Measured Raman spectra and electric resistivity indicate that a DLC film suitable for use as an insulating film can be produced on the micropipette. This coating method should also be useful for other extremely small probes.

  16. Plasma Spray-PVD: A New Thermal Spray Process to Deposit Out of the Vapor Phase

    NASA Astrophysics Data System (ADS)

    von Niessen, Konstantin; Gindrat, Malko

    2011-06-01

    Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years. In comparison to conventional vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS), the new proposed process uses a high energy plasma gun operated at a reduced work pressure of 0.1 kPa (1 mbar). Owing to the high energy plasma and further reduced work pressure, PS-PVD is able to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Owing to the forced gas stream of the plasma jet, complex shaped parts such as multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas which are not in the line of sight of the coating source can be coated homogeneously. This article reports on the progress made by Sulzer Metco in developing a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of Yttria-stabilized Zircona (YSZ) are optimized to serve in a turbine engine. This process includes not only preferable coating properties such as strain tolerance and erosion

  17. Surface modification of biomaterials by pulsed laser ablation deposition and plasma/gamma polymerization

    NASA Astrophysics Data System (ADS)

    Rau, Kaustubh R.

    Surface modification of stainless-steel was carried out by two different methods: pulsed laser ablation deposition (PLAD) and a combined plasma/gamma process. A potential application was the surface modification of endovascular stents, to enhance biocompatibility. The pulsed laser ablation deposition process, had not been previously reported for modifying stents and represented a unique and potentially important method for surface modification of biomaterials. Polydimethylsiloxane (PDMS) elatomer was studied using the PLAD technique. Cross- linked PDMS was deemed important because of its general use for biomedical implants and devices as well as in other fields. Furthermore, PDMS deposition using PLAD had not been previously studied and any information gained on its ablation characteristics could be important scientifically and technologically. The studies reported here showed that the deposited silicone film properties had a dependence on the laser energy density incident on the target. Smooth, hydrophobic, silicone-like films were deposited at low energy densities (100-150 mJ/cm2). At high energy densities (>200 mJ/cm2), the films had an higher oxygen content than PDMS, were hydrophilic and tended to show a more particulate morphology. It was also determined that (1)the deposited films were stable and extremely adherent to the substrate, (2)silicone deposition exhibited an `incubation effect' which led to the film properties changing with laser pulse number and (3)films deposited under high vacuum were similar to films deposited at low vacuum levels. The mechanical properties of the PLAD films were determined by nanomechanical measurements which are based on the Atomic Force Microscope (AFM). From these measurements, it was possible to determine the modulus of the films and also study their scratch resistance. Such measurement techniques represent a significant advance over current state-of-the-art thin film characterization methods. An empirical model for

  18. Energy deposition characteristics of nanosecond dielectric barrier discharge plasma actuators: Influence of dielectric material

    NASA Astrophysics Data System (ADS)

    Correale, G.; Winkel, R.; Kotsonis, M.

    2015-08-01

    An experimental study aimed at the characterization of energy deposition of nanosecond Dielectric Barrier Discharge (ns-DBD) plasma actuators was carried out. Special attention was given on the effect of the thickness and material used for dielectric barrier. The selected materials for this study were polyimide film (Kapton), polyamide based nylon (PA2200), and silicone rubber. Schlieren measurements were carried out in quiescent air conditions in order to observe density gradients induced by energy deposited. Size of heated area was used to qualify the energy deposition coupled with electrical power measurements performed using the back-current shunt technique. Additionally, light intensity measurements showed a different nature of discharge based upon the material used for barrier, for a fixed thickness and frequency of discharge. Finally, a characterisation study was performed for the three tested materials. Dielectric constant, volume resistivity, and thermal conductivity were measured. Strong trends between the control parameters and the energy deposited into the fluid during the discharge were observed. Results indicate that efficiency of energy deposition mechanism relative to the thickness of the barrier strongly depends upon the material used for the dielectric barrier itself. In general, a high dielectric strength and a low volumetric resistivity are preferred for a barrier, together with a high heat capacitance and a low thermal conductivity coefficient in order to maximize the efficiency of the thermal energy deposition induced by an ns-DBD plasma actuator.

  19. Conformal encapsulation of three-dimensional, bioresorbable polymeric scaffolds using plasma-enhanced chemical vapor deposition.

    PubMed

    Hawker, Morgan J; Pegalajar-Jurado, Adoracion; Fisher, Ellen R

    2014-10-21

    Bioresorbable polymers such as poly(ε-caprolactone) (PCL) have a multitude of potential biomaterial applications such as controlled-release drug delivery and regenerative tissue engineering. For such biological applications, the fabrication of porous three-dimensional bioresorbable materials with tunable surface chemistry is critical to maximize their surface-to-volume ratio, mimic the extracellular matrix, and increase drug-loading capacity. Here, two different fluorocarbon (FC) precursors (octofluoropropane (C3F8) and hexafluoropropylene oxide (HFPO)) were used to deposit FC films on PCL scaffolds using plasma-enhanced chemical vapor deposition (PECVD). These two coating systems were chosen with the intent of modifying the scaffold surfaces to be bio-nonreactive while maintaining desirable bulk properties of the scaffold. X-ray photoelectron spectroscopy showed high-CF2 content films were deposited on both the exterior and interior of PCL scaffolds and that deposition behavior is PECVD system specific. Scanning electron microscopy data confirmed that FC film deposition yielded conformal rather than blanket coatings as the porous scaffold structure was maintained after plasma treatment. Treated scaffolds seeded with human dermal fibroblasts (HDF) demonstrate that the cells do not attach after 72 h and that the scaffolds are noncytotoxic to HDF. This work demonstrates conformal FC coatings can be deposited on 3D polymeric scaffolds using PECVD to fabricate 3D bio-nonreactive materials.

  20. Influence of deposition rate on the structural properties of plasma-enhanced CVD epitaxial silicon

    NASA Astrophysics Data System (ADS)

    Chen, Wanghua; Cariou, Romain; Hamon, Gwenaëlle; Léal, Ronan; Maurice, Jean-Luc; Cabarrocas, Pere Roca I.

    2017-03-01

    Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C.

  1. Influence of deposition rate on the structural properties of plasma-enhanced CVD epitaxial silicon

    PubMed Central

    Chen, Wanghua; Cariou, Romain; Hamon, Gwenaëlle; Léal, Ronan; Maurice, Jean-Luc; Cabarrocas, Pere Roca i

    2017-01-01

    Solar cells based on epitaxial silicon layers as the absorber attract increasing attention because of the potential cost reduction. In this work, we studied the influence of the deposition rate on the structural properties of epitaxial silicon layers produced by plasma-enhanced chemical vapor deposition (epi-PECVD) using silane as a precursor and hydrogen as a carrier gas. We found that the crystalline quality of epi-PECVD layers depends on their thickness and deposition rate. Moreover, increasing the deposition rate may lead to epitaxy breakdown. In that case, we observe the formation of embedded amorphous silicon cones in the epi-PECVD layer. To explain this phenomenon, we develop a model based on the coupling of hydrogen and built-in strain. By optimizing the deposition conditions to avoid epitaxy breakdown, including substrate temperatures and plasma potential, we have been able to synthesize epi-PECVD layers up to a deposition rate of 8.3 Å/s. In such case, we found that the incorporation of hydrogen in the hydrogenated crystalline silicon can reach 4 at. % at a substrate temperature of 350 °C. PMID:28262840

  2. Deposition of PTFE thin films by RF plasma sputtering on <1 0 0> silicon substrates

    NASA Astrophysics Data System (ADS)

    Bodas, Dhananjay S.; Mandale, A. B.; Gangal, S. A.

    2005-05-01

    Polymers have been studied extensively due to the wonderful array of properties presented by them. Polymer materials can be coated/deposited by various techniques like sputtering (magnetron, ion beam, RF or dc), plasma polymerization, etc. and can be used in coatings, paint industries, etc. The present study deals with the RF sputter deposition of poly(tetrafluoro ethylene) (PTFE), commonly known as Teflon. Depositions were carried out on mirror polished silicon <1 0 0> substrates at different powers in the range of 100-200 W. The deposition time was kept constant at 60 min. The sputtered film shows lower contact angle of 50° with water and 44° with diiodomethane, a lower interfacial tension value of 0.76 dyne/cm, indicating hydrophilicity and good adhesion of the film with the substrate. FTIR indicates presence of C sbnd F, C sbnd F 2 bonding groups in the deposited film. Further, XPS study shows presence of CF 3 (292.2 eV), CF 2 (290.8 eV), C-F (288.0 eV) and C sbnd CF (286.4 eV) moieties indicating deposition of PTFE films at higher power levels of plasma.

  3. Optical properties of metal oxynitride thin films grown with atmospheric plasma deposition

    NASA Astrophysics Data System (ADS)

    Hovish, Michael Q.; Dauskardt, Reinhold H.

    2016-10-01

    Thin films of tantalum oxynitride (TaO x N y ) and titanium oxynitride (TiO x N y ) are deposited using atmospheric plasma deposition and a suite of optical properties are reported. Tantalum and titanium ethoxide are introduced into the afterglow of a radio-frequency capacitively coupled plasma, facilitating the growth of oxynitride films on silicon and polycarbonate at temperatures below 180 °C. The plasma power and nitrogen flow within the plasma are varied between 60 and 120 W and between 0.1 and 0.3 LPM respectively. We use spectroscopic ellipsometry to show that the optical properties of the metal oxynitride films grown in this study are comparable to those synthesized with sol-gel methods. Measurement of both the extinction coefficient and the transmission on polycarbonate substrates indicates good transparency in the visible wavelengths of light. Additionally, the refractive index increases when increasing the number of reactive nitrogen species within the discharge. We use x-ray photoelectron spectroscopy to correlate the higher indexes observed at large secondary gas flows to the presence of metal oxynitride bonding. Single layer anti-reflection coatings are deposited on silicon, with a five-fold and seven-fold reduction in reflection for TaO x N y and TiO x N y coatings, respectively. In total, we have found that the modulation of nitrogen concentration within the plasma discharge results in good control over optical constants. In addition, we observe similarities between films deposited with atmospheric plasma and those reported for sol-gel, indicating an alternative processing route where solution chemistries are currently applied.

  4. Growth of diamond by RF plasma-assisted chemical vapor deposition

    NASA Technical Reports Server (NTRS)

    Meyer, Duane E.; Ianno, Natale J.; Woollam, John A.; Swartzlander, A. B.; Nelson, A. J.

    1988-01-01

    A system has been designed and constructed to produce diamond particles by inductively coupled radio-frequency, plasma-assisted chemical vapor deposition. This is a low-pressure, low-temperature process used in an attempt to deposit diamond on substrates of glass, quartz, silicon, nickel, and boron nitride. Several deposition parameters have been varied including substrate temperature, gas concentration, gas pressure, total gas flow rate, RF input power, and deposition time. Analytical methods employed to determine composition and structure of the deposits include scanning electron microscopy, absorption spectroscopy, scanning Auger microprobe spectroscopy, and Raman spectroscopy. Analysis indicates that particles having a thin graphite surface, as well as diamond particles with no surface coatings, have been deposited. Deposits on quartz have exhibited optical bandgaps as high as 4.5 eV. Scanning electron microscopy analysis shows that particles are deposited on a pedestal which Auger spectroscopy indicates to be graphite. This is a phenomenon that has not been previously reported in the literature.

  5. Study on electrostatic and electromagnetic probes operated in ceramic and metallic depositing plasmas

    NASA Astrophysics Data System (ADS)

    Styrnoll, T.; Bienholz, S.; Lapke, M.; Awakowicz, P.

    2014-04-01

    This paper discusses plasma probe diagnostics, namely the multipole resonance probe (MRP) and Langmuir probe (LP), operated in depositing plasmas. The aim of this work is to show that the combination of both probes provides stable and robust measurements and clear determination of plasma parameters for metallic and ceramic coating processes. The probes use different approaches to determine plasma parameters, e.g. electron density ne and electron temperature Te. The LP is a well-established plasma diagnostic, and its applicability in technological plasmas is well documented. The LP is a dc probe that performs a voltage sweep and analyses the measured current, which makes it insensitive against conductive metallic coating. However, once the LP is dielectrically coated with a ceramic film, its functionality is constricted. In contrast, the MRP was recently presented as a monitoring tool, which is insensitive to coating with dielectric ceramics. It is a new plasma diagnostic based on the concept of active plasma resonance spectroscopy, which uses the universal characteristic of all plasmas to resonate on or near the electron plasma frequency. The MRP emits a frequency sweep and the absorption of the signal, the |S11| parameter, is analysed. Since the MRP concept is based on electromagnetic waves, which are able to transmit dielectrics, it is insensitive to dielectric coatings. But once the MRP is metallized with a thin conductive film, no undisturbed RF-signal can be emitted into the plasma, which leads to falsified plasma parameter. In order to compare both systems, during metallic or dielectric coating, the probes are operated in a magnetron CCP, which is equipped with a titanium target. We present measurements in metallic and dielectric coating processes with both probes and elaborate advantages and problems of each probe operated in each coating environment.

  6. Deposition of plasma polymerized perfluoromethylene-dominated films showing oil-repellency

    NASA Astrophysics Data System (ADS)

    Chase, J. E.; Boerio, F. J.

    2003-05-01

    Plasma polymerized fluorocarbon films were deposited onto polyethylene (PE) substrates to increase oil-repellency of PE. Depositions were performed using the monomer, 1H,1H,2H-perfluoro-1-dodecene in a parallel-plate, radio frequency (rf) reactor, with variable continuous-wave power ranging from 2 to 160 W. The film deposition rate and morphology were strongly dependent on the applied rf power. Most importantly, the chemical structure of the deposited films was also altered, resulting in changes in contact angles of various liquids and the surface energy. Films deposited at low power were composed mainly of perfluoromethylene (CF2) species (up to 67.2%), as shown by x-ray photoelectron spectroscopy (XPS). With an increase in rf power, CF2 content in the film decreased as further fragmentation of the monomer occurred. For each deposition at varying rf powers, even at powers as low as 2 W, the C=C and C-H bonds in the monomer were dissociated by the plasma and not incorporated into the films, as shown by Fourier transform infrared spectroscopy. Oil-repellency, as shown by increased contact angles of hydrocarbon liquids, was found to increase as the amount of CF2 species increased in the film structure. A low critical surface energy (2.7 mJ/m2) was calculated for the film deposited with only 2 W of rf power. Adhesion of the plasma-polymerized films to the PE was also evaluated and found to be poor for films with a high concentration of CF2 species, where cohesive failure within the film occurred. However, adhesion increased as a function of rf power, where the film structure showed more cross-linking. There was a compromise between producing a film with high oleophobicity (oil-repellency) while maintaining adhesion of the film to PE, as some disruption of the CF2 chains in the films was necessary for cohesion through cross-linking.

  7. Patterned growth of carbon nanotubes obtained by high density plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Mousinho, A. P.; Mansano, R. D.

    2015-03-01

    Patterned growth of carbon nanotubes by chemical vapor deposition represents an assembly approach to place and orient nanotubes at a stage as early as when they are synthesized. In this work, the carbon nanotubes were obtained at room temperature by High Density Plasmas Chemical Vapor Deposition (HDPCVD) system. This CVD system uses a new concept of plasma generation, where a planar coil coupled to an RF system for plasma generation was used with an electrostatic shield for plasma densification. In this mode, high density plasmas are obtained. We also report the patterned growth of carbon nanotubes on full 4-in Si wafers, using pure methane plasmas and iron as precursor material (seed). Photolithography processes were used to pattern the regions on the silicon wafers. The carbon nanotubes were characterized by micro-Raman spectroscopy, the spectra showed very single-walled carbon nanotubes axial vibration modes around 1590 cm-1 and radial breathing modes (RBM) around 120-400 cm-1, confirming that high quality of the carbon nanotubes obtained in this work. The carbon nanotubes were analyzed by atomic force microscopy and scanning electron microscopy too. The results showed that is possible obtain high-aligned carbon nanotubes with patterned growth on a silicon wafer with high reproducibility and control.

  8. Laser-induced metal plasmas for pulsed laser deposition of metal-oxide thin films

    NASA Astrophysics Data System (ADS)

    Wagenaars, Erik; Colgan, James; Rajendiran, Sudha; Rossall, Andrew

    2015-09-01

    Metal and metal-oxide thin films, e.g. ZnO, MgO, Al2O3 and TiO2, are widely used in e.g. microelectronics, catalysts, photonics and displays. Pulsed Laser Deposition (PLD) is a plasma-based thin-film deposition technique that is highly versatile and fast, however it suffers from limitations in control of film quality due to a lack of fundamental understanding of the underlying physical processes. We present experimental and modelling studies of the initial phases of PLD: laser ablation and plume expansion. A 2D hydrodynamic code, POLLUX, is used to model the laser-solid interaction of a Zn ablation with a Nd:YAG laser. In this early phase of PLD, the plasma plume has temperatures of about 10 eV, is highly ionized, and travels with a velocity of about 10-100 km/sec away from the target. Subsequently, the plasma enters the plume expansion phase in which the plasma cools down and collision chemistry changes the composition of the plume. Time-integrated optical emission spectroscopy shows that Zn I and Zn II emission lines dominate the visible range of the light emission. Comparison with the Los Alamos plasma kinetics code ATOMIC shows an average temperature around 1 eV, indicating a significant drop in plasma temperature during the expansion phase. We acknowledge support from the UK Engineering and Physical Sciences Research Council (EPSRC), Grant EP/K018388/1.

  9. Surface characterization of hydrophobic thin films deposited by inductively coupled and pulsed plasmas

    SciTech Connect

    Kim, Youngsoo; Lee, Ji-Hye; Kim, Kang-Jin; Lee, Yeonhee

    2009-07-15

    Different fluorocarbon thin films were deposited on Si substrates using a plasma-polymerization method. Fluorine-containing hydrophobic thin films were obtained by inductively coupled plasma (ICP) and pulsed plasma (PP) with a mixture of fluorocarbon precursors C{sub 2}F{sub 6}, C{sub 3}F{sub 8}, and c-C{sub 4}F{sub 8} and the unsaturated hydrocarbons of C{sub 2}H{sub 2}. The influence on the fluorocarbon surfaces of the process parameters for plasma polymerization, including the gas ratio and the plasma power, were investigated under two plasma-polymerized techniques with different fluorocarbon gas precursors. The hydrophobic properties, surface morphologies, and chemical compositions were elucidated using water contact angle measurements, field emission-scanning electron microscope, x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). In this study, the ICP technique provides coarser grained films and more hydrophobic surfaces as well as a higher deposition rate compared to the PP technique. XPS, FT-IR, and TOF-SIMS analyses indicated that the ICP technique produced more fluorine-related functional groups, including CF{sub 2} and CF{sub 3}, on the surface. From the curve-fitted XPS results, fluorocarbon films grown under ICP technique exhibited less degree of cross-linking and higher CF{sub 2} concentrations than those grown under PP technique.

  10. The influence of energy deposition parameters on laser plasma drag reduction

    NASA Astrophysics Data System (ADS)

    Dou, Zhiguo; Liu, Zhun; Yao, Honglin; Li, Xiuqian

    2013-09-01

    Laser plasma drag reduction is a new method to reduce the wave drag of hypersonic flight. The research of the laser plasma drag reduction performance is an important work. The purpose of this paper is investigating laser plasma drag reduction by numerical simulation to enhance the understanding of the drag reduction mechanism, get the drag reduction performance in different conditions, and provide references for laser plasma drag reduction experiment in the future. Based on summarizing correlative references systematically, through building the model of energy deposition and comparison the simulated results to the empirical formula and computation results to verify the program correctness, the influence of laser energy parameters to laser plasma drag reduction were simulated numerically for optimize the performance. The follow conclusions were got by numerical simulation: The computation program can well simulate the interacting of LSDW(laser supported detonation wave) to the bow shock in front of the blunt body. Results indicate that the blunt body drag could be decreased by injecting laser energy into the incoming hypersonic flow. The correctness of program was verified by compare result to the experiment and computation results. Blunt body drag will be greatly decreased with injected laser power increased, The bigger laser power is injected, the more drag decreases. There's an energy saturation value for each laser power level, the injecting laser power effectiveness values are never quite high for all laser power level. There is an optimized energy deposition location in upstream flow, this location is right ahead of the blunt body. When the distance from deposition location to the surface of blunt body is 5 times the blunt radius, blunt body drag decreased the most. This paper investigated the parameters which primary influence the performance of drag reduction. The numerical simulation data and obtained results are meaningful for laser plasma drag reduction

  11. Solid oxide fuel cell processing using plasma arc spray deposition techniques. Final report

    SciTech Connect

    Ray, E.R.; Spengler, C.J.; Herman, H.

    1991-07-01

    The Westinghouse Electric Corporation, in conjunction with the Thermal Spray Laboratory of the State University of New York, Stony Brook, investigated the fabrication of a gas-tight interconnect layer on a tubular solid oxide fuel cell with plasma arc spray deposition. The principal objective was to determine the process variables for the plasma spray deposition of an interconnect with adequate electrical conductivity and other desired properties. Plasma arc spray deposition is a process where the coating material in powder form is heated to or above its melting temperature, while being accelerated by a carrier gas stream through a high power electric arc. The molten powder particles are directed at the substrate, and on impact, form a coating consisting of many layers of overlapping, thin, lenticular particles or splats. The variables investigated were gun power, spray distance, powder feed rate, plasma gas flow rates, number of gun passes, powder size distribution, injection angle of powder into the plasma plume, vacuum or atmospheric plasma spraying, and substrate heating. Typically, coatings produced by both systems showed bands of lanthanum rich material and cracking with the coating. Preheating the substrate reduced but did not eliminate internal coating cracking. A uniformly thick, dense, adherent interconnect of the desired chemistry was finally achieved with sufficient gas- tightness to allow fabrication of cells and samples for measurement of physical and electrical properties. A cell was tested successfully at 1000{degree}C for over 1,000 hours demonstrating the mechanical, electrical, and chemical stability of a plasma-arc sprayed interconnect layer.

  12. Solid oxide fuel cell processing using plasma arc spray deposition techniques

    SciTech Connect

    Ray, E.R.; Spengler, C.J.; Herman, H.

    1991-07-01

    The Westinghouse Electric Corporation, in conjunction with the Thermal Spray Laboratory of the State University of New York, Stony Brook, investigated the fabrication of a gas-tight interconnect layer on a tubular solid oxide fuel cell with plasma arc spray deposition. The principal objective was to determine the process variables for the plasma spray deposition of an interconnect with adequate electrical conductivity and other desired properties. Plasma arc spray deposition is a process where the coating material in powder form is heated to or above its melting temperature, while being accelerated by a carrier gas stream through a high power electric arc. The molten powder particles are directed at the substrate, and on impact, form a coating consisting of many layers of overlapping, thin, lenticular particles or splats. The variables investigated were gun power, spray distance, powder feed rate, plasma gas flow rates, number of gun passes, powder size distribution, injection angle of powder into the plasma plume, vacuum or atmospheric plasma spraying, and substrate heating. Typically, coatings produced by both systems showed bands of lanthanum rich material and cracking with the coating. Preheating the substrate reduced but did not eliminate internal coating cracking. A uniformly thick, dense, adherent interconnect of the desired chemistry was finally achieved with sufficient gas- tightness to allow fabrication of cells and samples for measurement of physical and electrical properties. A cell was tested successfully at 1000{degree}C for over 1,000 hours demonstrating the mechanical, electrical, and chemical stability of a plasma-arc sprayed interconnect layer.

  13. The α and γ plasma modes in plasma-enhanced atomic layer deposition with O2–N2 capacitive discharges

    NASA Astrophysics Data System (ADS)

    Napari, M.; Tarvainen, O.; Kinnunen, S.; Arstila, K.; Julin, J.; Fjellvåg, Ø. S.; Weibye, K.; Nilsen, O.; Sajavaara, T.

    2017-03-01

    Two distinguishable plasma modes in the O2–N2 radio frequency capacitively coupled plasma (CCP) used in remote plasma-enhanced atomic layer deposition (PEALD) were observed. Optical emission spectroscopy and spectra interpretation with rate coefficient analysis of the relevant processes were used to connect the detected modes to the α and γ modes of the CCP discharge. To investigate the effect of the plasma modes on the PEALD film growth, ZnO and TiO2 films were deposited using both modes and compared to the films deposited using direct plasma. The growth rate, thickness uniformity, elemental composition, and crystallinity of the films were found to correlate with the deposition mode. In remote CCP operations the transition to the γ mode can result in a parasitic discharge leading to uncontrollable film growth and thus limit the operation parameters of the capacitive discharge in the PEALD applications.

  14. Plasma Membranes Modified by Plasma Treatment or Deposition as Solid Electrolytes for Potential Application in Solid Alkaline Fuel Cells

    PubMed Central

    Reinholdt, Marc; Ilie, Alina; Roualdès, Stéphanie; Frugier, Jérémy; Schieda, Mauricio; Coutanceau, Christophe; Martemianov, Serguei; Flaud, Valérie; Beche, Eric; Durand, Jean

    2012-01-01

    In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane. PMID:24958295

  15. Plasma membranes modified by plasma treatment or deposition as solid electrolytes for potential application in solid alkaline fuel cells.

    PubMed

    Reinholdt, Marc; Ilie, Alina; Roualdès, Stéphanie; Frugier, Jérémy; Schieda, Mauricio; Coutanceau, Christophe; Martemianov, Serguei; Flaud, Valérie; Beche, Eric; Durand, Jean

    2012-07-30

    In the highly competitive market of fuel cells, solid alkaline fuel cells using liquid fuel (such as cheap, non-toxic and non-valorized glycerol) and not requiring noble metal as catalyst seem quite promising. One of the main hurdles for emergence of such a technology is the development of a hydroxide-conducting membrane characterized by both high conductivity and low fuel permeability. Plasma treatments can enable to positively tune the main fuel cell membrane requirements. In this work, commercial ADP-Morgane® fluorinated polymer membranes and a new brand of cross-linked poly(aryl-ether) polymer membranes, named AMELI-32®, both containing quaternary ammonium functionalities, have been modified by argon plasma treatment or triallylamine-based plasma deposit. Under the concomitant etching/cross-linking/oxidation effects inherent to the plasma modification, transport properties (ionic exchange capacity, water uptake, ionic conductivity and fuel retention) of membranes have been improved. Consequently, using plasma modified ADP-Morgane® membrane as electrolyte in a solid alkaline fuel cell operating with glycerol as fuel has allowed increasing the maximum power density by a factor 3 when compared to the untreated membrane.

  16. Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition

    SciTech Connect

    Oliveira, M. H. Jr.; Viana, G. A.; Marques, F. C.; Lima, M. M. Jr. de; Cros, A.; Cantarero, A.

    2010-12-15

    Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH{sub 4}) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

  17. Influence of krypton atoms on the structure of hydrogenated amorphous carbon deposited by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Oliveira, M. H.; Viana, G. A.; de Lima, M. M.; Cros, A.; Cantarero, A.; Marques, F. C.

    2010-12-01

    Hydrogenated amorphous carbon (a-C:H) films were prepared by plasma enhanced chemical vapor deposition using methane (CH4) plus krypton (Kr) mixed atmosphere. The depositions were performed as function of the bias voltage and krypton partial pressure. The goal of this work was to study the influence of krypton gas on the physical properties of a-C:H films deposited on the cathode electrode. Krypton concentration up to 1.6 at. %, determined by Rutherford Back-Scattering, was obtained at high Kr partial pressure and bias of -120 V. The structure of the films was analyzed by means of optical transmission spectroscopy, multi-wavelength Raman scattering and Fourier Transform Infrared spectroscopy. It was verified that the structure of the films remains unchanged up to a concentration of Kr of about 1.0 at. %. A slight graphitization of the films occurs for higher concentration. The observed variation in the film structure, optical band gap, stress, and hydrogen concentration were associated mainly with the subplantation process of hydrocarbons radicals, rather than the krypton ion energy.

  18. Plasma Polymerisation of Maleic Anhydride: Just what are the right deposition conditions?

    PubMed Central

    Mishra, Gautam; McArthur, Sally L.

    2010-01-01

    Maleic anhydride plasma polymers enable amine containing biomolecules and polymers to be covalently coupled to a surface from an aqueous solution without any intermediate chemistry. The challenge in developing these functionally active plasma polymers lies in determining the optimal deposition conditions for producing a stable, highly active film. Unlike many previous studies that explore highly varied pulsed and continuous wave (CW) deposition conditions, this paper focuses on the comparison of films deposited under the same low nominal power conditions (1 W) and compares a range of CW, ms and µs pulsing parameters that can be used to produce this power condition. The use of attenuated total reflectance – Fourier transform infra red spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) has enabled the quantitative examination of the effects of processing parameters on the chemical functionality of the films. For the first time, the molecular specificity, surface sensitivity and high mass resolution of time-of-flight static secondary ion mass spectrometry (ToF-SSIMS) has been exploited to compare these films and multivariate analysis techniques used to explore the relationships between plasma processing parameters and surface chemistry. The results of the studies clearly demonstrate that a range of conditions can produce maleic anhydride films, with optimal functionality seen under µs pulsing regimes. Critically, the study demonstrates that the tight control and monitoring of the deposition parameters is critical if these films are to be manufactured with optimal functionality, stability and minimum processing time. PMID:20443591

  19. Effect of process parameters on properties of argon–nitrogen plasma for titanium nitride film deposition

    SciTech Connect

    Saikia, Partha; Kakati, Bharat

    2013-11-15

    In this study, the effect of working pressure and input power on the physical properties and sputtering efficiencies of argon–nitrogen (Ar/N{sub 2}) plasma in direct current magnetron discharge is investigated. The discharge in Ar/N{sub 2} is used to deposit TiN films on high speed steel substrate. The physical plasma parameters are determined by using Langmuir probe and optical emission spectroscopy. On the basis of the different reactions in the gas phase, the variation of plasma parameters and sputtering rate are explained. A prominent change of electron temperature, electron density, ion density, and degree of ionization of Ar is found as a function of working pressure and input power. The results also show that increasing working pressure exerts a negative effect on film deposition rate while increasing input power has a positive impact on the same. To confirm the observed physical properties and evaluate the texture growth as a function of deposition parameters, x-ray diffraction study of deposited TiN films is also done.

  20. Deposition of Fluorinated Diamond-Like-Carbon Films by Exposure of Electrothermal Pulsed Plasmas

    NASA Astrophysics Data System (ADS)

    Kimura, Takashi; Iida, Masayasu

    2011-08-01

    Thin amorphous carbon films are deposited on silicon substrates by exposure to pulsed plasmas where the feed gas is mainly generated from the ablation of an insulator. An electrothermal pulsed plasma thruster with a discharge room in an insulator rod is used as the pulsed plasma for the ablation of the insulator, and the material of the insulator rod is poly(tetrafluoroethylene) (PTFE). The pulsed plasma, in which the estimated electron density is on the order of 1022-1023 m-3, is generated by the stored energy in the capacitor. The deposition rate, which depends on the stored energy, is lower than 1 nm per pulse in our experiment. The maximum hardness measured using a nanoindenter is about 7 GPa at a stored energy of about 2.7 J, beyond which the hardness of the films decreases with the increase in stored energy. Raman spectroscopy is also carried out to examine the formation of fluorinated diamond-like carbon films. In addition, the influence of dilution gas on the properties of the deposited films is also investigated.

  1. Microwave plasma assisted process for cleaning and deposition in future semiconductor technology

    NASA Astrophysics Data System (ADS)

    Altmannshofer, S.; Boudaden, J.; Wieland, R.; Eisele, I.; Kutter, C.

    2017-06-01

    The epitaxial growth of silicon layers is an important step in the fabrication of semiconductor devices. For conventional silicon epitaxy, high temperatures, up to 900 °C are necessary. However, in future, semiconductor technology epitaxy processes at lower temperatures are required to increase the integration density. The goal of this study was to investigate microwave plasma assisted processes for the selective removing of thin silicon oxide, the cleaning of silicon surfaces and the depositing of high quality silicon films. The main focus was to apply these processes for low temperature epitaxy. All processes, such as oxide removal, cleaning and deposition, were done in one chamber and with microwave plasma assistance. In order to remove silicon dioxide, the etching behavior of hydrogen, fluorine, and hydrogen/fluorine plasma was studied. It was shown, that with hydrogen/fluorine plasma, the best selectivity of oxide to silicon was reached. The deposition process of silicon was studied by growing μc-Si films. The process was characterized and optimized by spectral ellipsometry. After a successful characterization of all process steps, silicon epitaxy layers have been grown with in-situ removal of native oxide and in-situ surface cleaning. The temperature for all process steps was reduced below 450 °C.

  2. Tailoring carbon nanotips in the plasma-assisted chemical vapor deposition: Effect of the process parameters

    SciTech Connect

    Wang, B. B.; Ostrikov, K.

    2009-04-15

    Carbon nanotips have been synthesized from a thin carbon film deposited on silicon by bias-enhanced hot filament chemical vapor deposition under different process parameters. The results of scanning electron microscopy indicate that high-quality carbon nanotips can only be obtained under conditions when the ion flux is effectively drawn from the plasma sustained in a CH{sub 4}+NH{sub 3}+H{sub 2} gas mixture. It is shown that the morphology of the carbon nanotips can be controlled by varying the process parameters such as the applied bias, gas pressure, and the NH{sub 3}/H{sub 2} mass flow ratios. The nanotip formation process is examined through a model that accounts for surface diffusion, in addition to sputtering and deposition processes included in the existing models. This model makes it possible to explain the major difference in the morphologies of the carbon nanotips formed without and with the aid of the plasma as well as to interpret the changes of their aspect ratio caused by the variation in the ion/gas fluxes. Viable ways to optimize the plasma-based process parameters to synthesize high-quality carbon nanotips are suggested. The results are relevant to the development of advanced plasma-/ion-assisted methods of nanoscale synthesis and processing.

  3. Measuring atomic oxygen densities and electron properties in an Inductively Coupled Plasma for thin film deposition

    NASA Astrophysics Data System (ADS)

    Meehan, David; Gibson, Andrew; Booth, Jean-Paul; Wagenaars, Erik

    2016-09-01

    Plasma Enhanced Pulsed Laser Deposition (PE-PLD) is an advanced way of depositing thin films of oxide materials by using a laser to ablate a target, and passing the resulting plasma plume through a background Inductively-Coupled Plasma (ICP), instead of a background gas as is done in traditional PLD. The main advantage of PE-PLD is the control of film stoichiometry via the direct control of the reactive oxygen species in the ICP instead of relying on a neutral gas background. The aim is to deposit zinc oxide films from a zinc metal target and an oxygen ICP. In this work, we characterise the range of compositions of the reactive oxygen species achievable in ICPs; in particular the atomic oxygen density. The density of atomic oxygen has been determined within two ICPs of two different geometries over a range of plasma powers and pressures with the use of Energy Resolved Actinometry (ERA). ERA is a robust diagnostic technique with determines both the dissociation degree and average electron energy by comparing the excitation ratios of two oxygen and one argon transition. Alongside this the electron densities have been determined with the use of a hairpin probe. This work received financial support from the EPSRC, and York-Paris CIRC.

  4. Modeling of microcrystalline silicon film deposition in a capacitively coupled radio-frequency plasma reactor

    SciTech Connect

    Satake, Koji; Kobayashi, Yasuyuki

    2005-01-15

    We present a numerical model of plasma-enhanced chemical-vapor deposition of hydrogenated microcrystalline silicon ({mu}c-Si:H) film from SiH{sub 4} and H{sub 2} gas mixtures in a capacitively coupled radio-frequency plasma reactor. The model takes into account electron-impact, gas-phase, and surface reactions within a well-mixed reactor model. Plasma parameters such as the electron density, the electron temperature, and the electron-impact reaction rates are determined through a discharge model and used as inputs for the reactor model. The gas-phase reactions include electron-impact and neutral-neutral reactions. Some of the surface reaction rates are determined using quantum chemical calculations and transition state theory. In the reactor model, concentrations of each chemical species are calculated at steady state using mass conservation equation uniformed throughout the reactor. Numerical results of the deposition rate as a function of the plasma reactor operating parameters show good agreement with experiments. Based on the model, the correlation between {mu}c-Si:H properties, such as the crystal grain orientation and the hydrogen content, and deposition operating parameters has been studied using a design of experiment. Finally, optimal operating parameters are investigated using optimization techniques.

  5. Drop coating deposition Raman spectroscopy of blood plasma for the detection of colorectal cancer.

    PubMed

    Li, Pengpeng; Chen, Changshui; Deng, Xiaoyuan; Mao, Hua; Jin, Shaoqin

    2015-03-01

    We have recently applied the technique of drop coating deposition Raman (DCDR) spectroscopy for colorectal cancer (CRC) detection using blood plasma. The aim of this study was to develop a more convenient and stable method based on blood plasma for noninvasive CRC detection. Significant differences are observed in DCDR spectra between healthy (n = 105) and cancer (n = 75) plasma from 15 CRC patients and 21 volunteers, particularly in the spectra that are related to proteins, nucleic acids, and β-carotene. The multivariate analysis principal components analysis and the linear discriminate analysis, together with leave-one-out, cross validation were used on DCDR spectra and yielded a sensitivity of 100% (75/75) and specificity of 98.1% (103/105) for detection of CRC. This study demonstrates that DCDR spectroscopy of blood plasma associated with multivariate statistical algorithms has the potential for the noninvasive detection of CRC.

  6. INSTRUMENTS AND METHODS OF INVESTIGATION: Modification of material properties and coating deposition using plasma jets

    NASA Astrophysics Data System (ADS)

    Pogrebnyak, Alexander D.; Tyurin, Yu N.

    2005-05-01

    The review is concerned with the current status of research on the use of plasma jets for the modification of surface properties of metalware, as well as of investigations of doping and mass transfer of elements. The effect of thermal plasma parameters on the efficiency of surface processing of metal materials is discussed. The structure and properties of protective coatings produced by exposure to pulsed plasmas are analyzed. A new direction for the production of combined coatings is considered. Their structure and properties were studied by the example of Fe, Cu, steels, and alloys, including titanium alloys; the modification process was shown to be controllable by the action of pulsed plasma jets. The physical factors that affect the modification process and the coating deposition, and their effect on the structure and properties of metallic, ceramic - metal, and ceramic coatings were analyzed.

  7. Drop coating deposition Raman spectroscopy of blood plasma for the detection of colorectal cancer

    NASA Astrophysics Data System (ADS)

    Li, Pengpeng; Chen, Changshui; Deng, Xiaoyuan; Mao, Hua; Jin, Shaoqin

    2015-03-01

    We have recently applied the technique of drop coating deposition Raman (DCDR) spectroscopy for colorectal cancer (CRC) detection using blood plasma. The aim of this study was to develop a more convenient and stable method based on blood plasma for noninvasive CRC detection. Significant differences are observed in DCDR spectra between healthy (n=105) and cancer (n=75) plasma from 15 CRC patients and 21 volunteers, particularly in the spectra that are related to proteins, nucleic acids, and β-carotene. The multivariate analysis principal components analysis and the linear discriminate analysis, together with leave-one-out, cross validation were used on DCDR spectra and yielded a sensitivity of 100% (75/75) and specificity of 98.1% (103/105) for detection of CRC. This study demonstrates that DCDR spectroscopy of blood plasma associated with multivariate statistical algorithms has the potential for the noninvasive detection of CRC.

  8. Surface field of forces and protein adsorption behavior of poly(hydroxyethylmethacrylate) films deposited from plasma.

    PubMed

    Morra, M; Cassinelli, C

    1995-01-01

    Polymeric films were deposited from hydroxyethylmethacrylate (HEMA) plasma on non-woven poly(butyleneterephtalate) (PBT) filter materials. To test the effect of deposition conditions on surface properties, film were deposited using a constant monomer flow rate and a discharge power ranging from 40-100 W. Surface composition and surface energetics were evaluated by Electron Spectroscopy for Chemical Analysis (ESCA) and contact angle measurement, respectively. Albumin (Alb) and fibrinogen (Fg) adsorption from single protein solutions to the plasma-coated filters was measured. Results illustrate the marked effects of the deposition condition on the surface composition, the surface field of forces, and the protein adsorption behavior. The latter is modeled by the application of the Good-van Oss-Chaudhury theory of Lewis acid-base contribution to interfacial energetics. Materials endowed with widely different properties are obtained from the same monomer and different deposition conditions, a result that must be taken into account both in the production step, to assure constant quality, and in the development of specifically tailored materials.

  9. Enhancement of octacalcium phosphate deposition on a titanium surface activated by electron cyclotron resonance plasma oxidation.

    PubMed

    Orii, Yusuke; Masumoto, Hiroshi; Honda, Yoshitomo; Anada, Takahisa; Goto, Takashi; Sasaki, Keiichi; Suzuki, Osamu

    2010-05-01

    The present study was designed to investigate whether the formation of octacalcium phosphate (OCP) is accelerated on titanium (Ti) surface by an electron cyclotron resonance (ECR) plasma oxidation at various pressures and temperatures. X-ray diffraction (XRD) of Ti-oxidized substrates showed that the rutile TiO(2) phase on its surfaces appeared at 300 degrees C and was crystallized when the oxidation temperature increased up to 600 degrees C. The thickness of TiO(2) film on the substrates increased progressively as the temperature increased. The oxidized Ti surfaces were soaked in calcium and phosphate solutions supersaturated with respect to both hydroxyapatite (HA) and OCP but slightly supersaturated with dicalcium phosphate dihydrate (DCPD). OCP crystals with a blade-like morphology were deposited as the primary crystalline phase on Ti substrates, while DCPD was included as a minor constituent. The amount of OCP deposition was maximized under 0.015 Pa in 300 degrees C. On the other hand, the oxidation temperature did not show a significant effect on the deposit in the range examined. The phase conversion from OCP to HA, determined by XRD, was demonstrated to occur even at 1 day and to advance until 7 days by immersing the Ti substrate with the deposit in simulated body fluid at 37 degrees C. The present results suggest that ECR plasma oxidation could be used to improve a Ti surface regarding its bioactivity due to the enhancement of osteoconductive OCP deposition. (c) 2010 Wiley Periodicals, Inc.

  10. Near room-temperature direct encapsulation of organic photovoltaics by plasma-based deposition techniques

    NASA Astrophysics Data System (ADS)

    Perrotta, Alberto; Fuentes-Hernandez, Canek; Khan, Talha M.; Kippelen, Bernard; Creatore, Mariadriana; Graham, Samuel

    2017-01-01

    Plasma-assisted atomic layer deposition (ALD) is used for the deposition of environmental barriers directly onto organic photovoltaic devices (OPVs) at near room temperature (30 °C). To study the effect of the ALD process on the organic materials forming the device, the precursor diffusion and intermixing at the interface during the growth of different plasma-assisted ALD inorganic barriers (i.e. Al2O3 and TiO2) onto the organic photoactive layer (P3HT:ICBA) was investigated. Depth profile x-ray photoelectron spectroscopy was used to analyze the composition of the organic/inorganic interface to investigate the infiltration of the plasma-assisted ALD precursors into the photoactive layer as a function of the precursor dimension, the process temperature, and organic layer morphology. The free volume in the photoactive layer accessible to the ALD precursor was characterized by means of ellipsometric porosimetry (EP) and spectroscopic ellipsometry as a function of temperature. The organic layer is shown to exhibit free volume broadening at high temperatures, increasing the infiltration depth of the ALD precursor into the photoactive layer. Furthermore, based on previous investigations, the intrinsic permeation properties of the inorganic layers deposited by plasma-assisted ALD were predicted from the nano-porosity content as measured by EP and found to be in the 10-6 gm-2 d-1 range. Insight from our studies was used to design and fabricate multilayer barriers synthesized at near-room temperature by plasma-assisted ALD in combination with plasma-enhanced CVD onto organic photovoltaic (OPVs) devices. Encapsulated OPVs displayed shelf-lifetimes up to 1400 h at ambient conditions.

  11. Electrical transport properties of microcrystalline silicon grown by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Pinto, Nicola; Ficcadenti, Marco; Morresi, Lorenzo; Murri, Roberto; Ambrosone, Giuseppina; Coscia, Ubaldo

    2004-12-01

    The dark conductivity and Hall mobility of hydrogenated silicon films deposited varying the silane concentration f =SiH4/(SiH4+H2) in a conventional plasma enhanced chemical vapor deposition system have been investigated as a function of temperature, taking into account their structural properties. The electrical properties have been studied in terms of a structural two-phase model. A clear transition from the electrical transport governed by a crystalline phase, in the range 1%⩽f⩽3%, to that controlled by an amorphous phase, for f >3%, has been evidenced. Some metastable effects of the dark conductivity have been noticed.

  12. Plasma-enhanced chemical vapor deposition of β-tungsten, a metastable phase

    NASA Astrophysics Data System (ADS)

    Tang, C. C.; Hess, D. W.

    1984-09-01

    Plasma-enhanced chemical vapor deposition of a metastable phase of tungsten ( β-W) is performed using tungsten hexafluoride and hydrogen as source gases. At 350 °C, the as-deposited resistivity of these films is ˜50 μΩ cm. After heat treatments between 650 and 750 °C in forming gas, the resistivity drops below 11 μΩ cm. Concomitant with this resistivity change is a phase change to α-W, the equilibrium, body-centered-cubic form.

  13. Growth mechanism of carbon nanotubes grown by microwave plasma-assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Muneyoshi, T.; Okai, M.; Yaguchi, T.; Sasaki, S.

    2001-10-01

    To investigate the most suitable deposition conditions and growth mechanism, we grew carbon nanotubes (CNTs) by microwave plasma-assisted chemical vapor deposition under various conditions. The experimental parameters we varied were (a) the mixture ratio of methane in hydrogen, (b) the total gas pressure, and (c) the bias electric current. We found that the bias electric current was the most influential parameter in determining the shape of CNTs. We believe that the growth process of CNTs can be explained by using the solid solubility curves of metal-carbon phase diagrams. Selective growth and low-temperature growth of CNTs can also be understood from these phase diagrams.

  14. Properties of Plasma Enhanced Chemical Vapor Deposition Barrier Coatings and Encapsulated Polymer Solar Cells

    NASA Astrophysics Data System (ADS)

    Qi, Lei; Zhang, Chunmei; Chen, Qiang

    2014-01-01

    In this paper, we report silicon oxide coatings deposited by plasma enhanced chemical vapor deposition technology (PECVD) on 125 μm polyethyleneterephthalate (PET) surfaces for the purpose of the shelf lifetime extension of sealed polymer solar cells. After optimization of the processing parameters, we achieved a water vapor transmission rate (WVTR) of ca. 10-3 g/m2/day with the oxygen transmission rate (OTR) less than 0.05 cc/m2/day, and succeeded in extending the shelf lifetime to about 400 h in encapsulated solar cells. And then the chemical structure of coatings related to the properties of encapsulated cell was investigated in detail.

  15. Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

    NASA Astrophysics Data System (ADS)

    Fan, E. S. C.; Kesler, O.

    2015-08-01

    Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

  16. Evolution of the calcium hydroxyapatite crystal structure under plasma deposition and subsequent reducing treatment

    NASA Astrophysics Data System (ADS)

    Shamrai, V. F.; Karpikhin, A. E.; Sirotinkin, V. P.; Kalita, V. I.; Komlev, D. I.

    2014-03-01

    The structure of hydroxyapatite plasma coatings on a titanium substrate has been investigated by the X-ray Rietveld method. The hydroxyapatite crystal structure in plasma-deposited samples is characterized by strong distortions of its main element (tetrahedral PO4 cluster) and coordination calcium polyhedra, as well as calcium deficit in the Ca2 site; however, these features do not change the main motif of the hydroxyapatite structure. The bond distortions in PO4 clusters are estimated by the Bauer method. It is shown that hydrothermal treatment leads to the almost complete recovery of the hydroxyapatite structure.

  17. Influence of argon plasma on the deposition of Al2O3 film onto the PET surfaces by atomic layer deposition.

    PubMed

    Edy, Riyanto; Huang, Xiaojiang; Guo, Ying; Zhang, Jing; Shi, Jianjun

    2013-02-15

    In this paper, polyethyleneterephthalate (PET) films with and without plasma pretreatment were modified by atomic layer deposition (ALD) and plasma-assisted atomic layer deposition (PA-ALD). It demonstrates that the Al2O3 films are successfully deposited onto the surface of PET films. The cracks formed on the deposited Al2O3 films in the ALD, plasma pretreated ALD, and PA-ALD were attributed to the energetic ion bombardment in plasmas. The surface wettability in terms of water contact angle shows that the deposited Al2O3 layer can enhance the wetting property of modified PET surface. Further characterizations of the Al2O3 films suggest that the elevated density of hydroxyl -OH group improve the initial growth of ALD deposition. Chemical composition of the Al2O3-coated PET film was characterized by X-ray photoelectron spectroscopy, which shows that the content of C 1s reduces with the growing of O 1s in the Al2O3-coated PET films, and the introduction of plasma in the ALD process helps the normal growth of Al2O3 on PET in PA-ALD.

  18. Atmospheric inductively coupled Ar/H2 plasmas jet for low-temperature deposition of Cu Thin Film on Polyimide

    NASA Astrophysics Data System (ADS)

    Zhao, Peng; Zheng, Wei; Meng, Yuedong; Nagatsu, Masaaki

    2013-09-01

    For fabrication of future flexible electronic devices and depositing Cu thin films on polyimide substrate at low temperature, an atmospheric inductively coupled plasma jet driven by a 13.56 MHz radio frequency (RF) power is developed. In previous studies, we found that by adding a fractional amount of H2 gas into Ar plasma, quality of Cu film was significantly improved. But under air atmosphere, the oxidization of deposited film is inevitable. So we developed the technology in nitrogen atmosphere. We invested the plasma jet properties of Ar plasma in air, Ar/ H2 plasma in air and Ar/ H2 plasma in nitrogen atmosphere, to discuss the effect of adding H2 to Ar plasma and nitrogen background on plasma properties. The plasma gas temperature diagnoses and chemical reaction research during deposition were performed by OES. The plasma jet non-equilibrium numeral simulations were also carried out for thermal and transport properties during deposition. The effects on Cu films quality were studied by means of XPS and SEM. All the plasma properties and the results of Cu film would give us an insight on the mechanism and the possibility of improving the process.

  19. Ag films grown by remote plasma enhanced atomic layer deposition on different substrates

    SciTech Connect

    Amusan, Akinwumi A. Kalkofen, Bodo; Burte, Edmund P.; Gargouri, Hassan; Wandel, Klaus; Pinnow, Cay; Lisker, Marco

    2016-01-15

    Silver (Ag) layers were deposited by remote plasma enhanced atomic layer deposition (PALD) using Ag(fod)(PEt{sub 3}) (fod = 2,2-dimethyl-6,6,7,7,8,8,8-heptafluorooctane-3,5-dionato) as precursor and hydrogen plasma on silicon substrate covered with thin films of SiO{sub 2}, TiN, Ti/TiN, Co, Ni, and W at different deposition temperatures from 70  to 200 °C. The deposited silver films were analyzed by x-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) with energy dispersive x-ray spectroscopy, four point probe measurement, ellipsometric measurement, x-ray fluorescence (XRF), and x-ray diffraction (XRD). XPS revealed pure Ag with carbon and oxygen contamination close to the detection limit after 30 s argon sputtering for depositions made at 120 and 200 °C substrate temperatures. However, an oxygen contamination was detected in the Ag film deposited at 70 °C after 12 s argon sputtering. A resistivity of 5.7 × 10{sup −6} Ω cm was obtained for approximately 97 nm Ag film on SiO{sub 2}/Si substrate. The thickness was determined from the SEM cross section on the SiO{sub 2}/Si substrate and also compared with XRF measurements. Polycrystalline cubic Ag reflections were identified from XRD for PALD Ag films deposited at 120 and 200 °C. Compared to W surface, where poor adhesion of the films was found, Co, Ni, TiN, Ti/TiN and SiO{sub 2} surfaces had better adhesion for silver films as revealed by SEM, TEM, and AFM images.

  20. Shaping thin film growth and microstructure pathways via plasma and deposition energy: a detailed theoretical, computational and experimental analysis.

    PubMed

    Sahu, Bibhuti Bhusan; Han, Jeon Geon; Kersten, Holger

    2017-02-15

    Understanding the science and engineering of thin films using plasma assisted deposition methods with controlled growth and microstructure is a key issue in modern nanotechnology, impacting both fundamental research and technological applications. Different plasma parameters like electrons, ions, radical species and neutrals play a critical role in nucleation and growth and the corresponding film microstructure as well as plasma-induced surface chemistry. The film microstructure is also closely associated with deposition energy which is controlled by electrons, ions, radical species and activated neutrals. The integrated studies on the fundamental physical properties that govern the plasmas seek to determine their structure and modification capabilities under specific experimental conditions. There is a requirement for identification, determination, and quantification of the surface activity of the species in the plasma. Here, we report a detailed study of hydrogenated amorphous and crystalline silicon (c-Si:H) processes to investigate the evolution of plasma parameters using a theoretical model. The deposition processes undertaken using a plasma enhanced chemical vapor deposition method are characterized by a reactive mixture of hydrogen and silane. Later, various contributions of energy fluxes on the substrate are considered and modeled to investigate their role in the growth of the microstructure of the deposited film. Numerous plasma diagnostic tools are used to compare the experimental data with the theoretical results. The film growth and microstructure are evaluated in light of deposition energy flux under different operating conditions.

  1. Deposition and characterization of molybdenum thin films using dc-plasma magnetron sputtering

    SciTech Connect

    Khan, Majid; Islam, Mohammad

    2013-12-15

    Molebdenum (Mo) thin films were deposited on well-cleaned soda-lime glass substrates using DC-plasma magnetron sputtering. In the design of experiment deposition was optimized for maximum beneficial characteristics by monitoring effect of process variables such as deposition power (100–200 W). Their electrical, structural and morphological properties were analyzed to study the effect of these variables. The electrical resistivity of Mo thin films could be reduced by increasing deposition power. Within the range of analyzed deposition power, Mo thin films showed a mono crystalline nature and the crystallites were found to have an orientation along [110] direction. The surface morphology of thin films showed that a highly dense micro structure has been obtained. The surface roughness of films increased with deposition power. The adhesion of Mo thin films could be improved by increasing the deposition power. Atomic force microscopy was used for the topographical study of the films and to determine the roughness of the films. X-ray diffractrometer and scanning electron microscopy analysis were used to investigate the crystallinity and surface morphology of the films. Hall effect measurement system was used to find resistivity, carrier mobility and carrier density of deposited films. The adhesion test was performed using scotch hatch tape adhesion test. Mo thin films prepared at deposition power of 200 W, substrate temperature of 23°C and Ar pressure of 0.0123 mbar exhibited a mono crystalline structure with an orientation along (110) direction, thickness of ∼550 nm and electrical resistivity value of 0.57 × 10{sup −4} Ω cm.

  2. Development of dielectric barrier discharge plasma processing apparatus for mass spectrometry and thin film deposition

    NASA Astrophysics Data System (ADS)

    Majumdar, Abhijit; Hippler, Rainer

    2007-07-01

    Cost effective and a very simple dielectric barrier discharge plasma processing apparatus for thin film deposition and mass spectroscopic analysis of organic gas mixture has been described. The interesting features of the apparatus are the construction of the dielectric electrodes made of aluminum oxide or alumina (Al2O3) and glass and the generation of high ignition voltage from the spark plug transformer taken from car. Metal capacitor is introduced in between ground and oscilloscope to measure the executing power during the discharge and the average electron density in the plasma region. The organic polymer films have been deposited on Si (100) substrate using several organic gas compositions. The experimental setup provides a unique drainage system from the reaction chamber controlled by a membrane pump to suck out and remove the poisonous gases or residuals (cyanogens, H-CN, CHxNH2, etc.) which have been produced during the discharge of CH4/N2 mixture.

  3. Fast electron energy deposition in a magnetized plasma: Kinetic theory and particle-in-cell simulation

    SciTech Connect

    Robiche, J.; Rax, J.-M.; Bonnaud, G.; Gremillet, L.

    2010-03-15

    The collisional dynamics of a relativistic electron jet in a magnetized plasma are investigated within the framework of kinetic theory. The relativistic Fokker-Planck equation describing slowing down, pitch angle scattering, and cyclotron rotation is derived and solved. Based on the solution of this Fokker-Planck equation, an analytical formula for the root mean square spot size transverse to the magnetic field is derived and this result predicts a reduction in radial transport. Some comparisons with particle-in-cell simulation are made and confirm striking agreement between the theory and the simulation. For fast electron with 1 MeV typical kinetic energy interacting with a solid density hydrogen plasma, the energy deposition density in the transverse direction increases by a factor 2 for magnetic field of the order of 1 T. Along the magnetic field, the energy deposition profile is unaltered compared with the field-free case.

  4. Surface interactions of CF2 radicals during deposition of amorphous fluorocarbon films from CHF3 plasmas

    NASA Astrophysics Data System (ADS)

    Capps, Nathan E.; Mackie, Neil M.; Fisher, Ellen R.

    1998-11-01

    Surface reactivities for CF2 radicals formed in a CHF3 plasma molecular beam are measured during film deposition on a variety of substrates. The imaging of radicals interacting with surfaces (IRIS) technique was used to collect spatially resolved laser-induced fluorescence (LIF) images of CF2 radicals interacting with SiO2, Si3N4, Si, 304 stainless steel, and system 8 photoresist substrates. Films deposited during IRIS experiments were characterized using x-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy and were found to be nearly identical in composition on all substrates. Simulation of LIF cross-sectional data shows high scattering coefficients for CF2 radicals on all substrates. These extremely large scattering coefficients (>1.0) indicate that CF2 molecules are generated through plasma interactions with the substrate. Possible CF2 surface generation mechanisms are discussed, with consideration of CF and ion bombardment contributions to the generation of CF2.

  5. Development of dielectric barrier discharge plasma processing apparatus for mass spectrometry and thin film deposition.

    PubMed

    Majumdar, Abhijit; Hippler, Rainer

    2007-07-01

    Cost effective and a very simple dielectric barrier discharge plasma processing apparatus for thin film deposition and mass spectroscopic analysis of organic gas mixture has been described. The interesting features of the apparatus are the construction of the dielectric electrodes made of aluminum oxide or alumina (Al(2)O(3)) and glass and the generation of high ignition voltage from the spark plug transformer taken from car. Metal capacitor is introduced in between ground and oscilloscope to measure the executing power during the discharge and the average electron density in the plasma region. The organic polymer films have been deposited on Si (100) substrate using several organic gas compositions. The experimental setup provides a unique drainage system from the reaction chamber controlled by a membrane pump to suck out and remove the poisonous gases or residuals (cyanogens, H-CN, CH(x)NH(2), etc.) which have been produced during the discharge of CH(4)N(2) mixture.

  6. Optimization of plasma deposition and etching processes for commercial multicrystalline silicon solar cells

    SciTech Connect

    Ruby, D.S.; Wilbanks, W.L.; Fleddermann, C.B.; Rosenblum, M.D.; Roncin, S.; Narayanan, S.

    1996-06-01

    The authors conducted an investigation of plasma deposition and etching processes on full-size multicrystalline (mc-Si) cells processed in commercial production lines, so that any improvements obtained will be immediately relevant to the PV industry. In one case, the authors performed a statistically designed multiparameter experiment to determine the optimum PECVD-nitride deposition conditions specific to EFG silicon from ASE Americas, Inc. In a related effort, they studied whether plasma-etching techniques can use standard screen-printed gridlines as etch masks to form self-aligned, patterned-emitter profiles on mc-Si cells from Solarex Corp. Initial results found a statistically significant improvement of about half an absolute percentage point in cell efficiency when the self-aligned emitter etchback was combined with the PECVD-nitride surface passivation treatment. Additional improvement is expected when the successful bulk passivation treatment is also added to the process.

  7. Growing oriented AlN films on sapphire substrates by plasma-enhanced atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Tarala, V. A.; Altakhov, A. S.; Ambartsumov, M. G.; Martens, V. Ya.

    2017-01-01

    The possibility of growing oriented AlN films on Al2O3 substrates at temperatures below 300°C by plasma-enhanced atomic layer deposition was examined. The samples were subjected to X-ray phase analysis and ellipsometry. It was demonstrated that the refraction index of films deposited with plasma exposures longer than 20 s was 2.03 ± 0.03. The (0002) and (0004) reflections at 2Θ angles of 35.7° and 75.9° were present in the X-ray diffraction patterns of these samples. These reflections are typical of the hexagonal AlN polytype. The full width at half maximum of the rocking curve of reflection (0002) in the best sample was 162 ± 11 arcsec.

  8. Deposition of a-SiC:H using organosilanes in an argon/hydrogen plasma

    SciTech Connect

    Maya, L.

    1993-12-01

    Selected organosilanes were examined as precursors for the deposition of amorphous hydrogenated silicon carbide in an argon/hydrogen plasma. Effect of process variables on the quality of the films was established by means of FTIR, Auger spectroscopy, XPS, XRD, chemical analysis, and weight losses upon pyrolysis. For a given power level there is a limiting feeding rate of the precursor under which operation of the system is dominated by thermodynamics and leads to high quality silicon carbide films that are nearly stoichiometric and low in hydrogen. Beyond that limit, carbosilane polymer formation and excessive hydrogen incorporation takes place. The hydrogen content of the plasma affects the deposition rate and the hydrogen content of the film. In the thermodynamically dominated regime the nature of the precursor has no effect on the quality of the film, it affects only the relative utilization efficiency.

  9. Status of Plasma Physics Techniques for the Deposition of Tribological Coatings

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1984-01-01

    The plasma physics deposition techniques of sputtering and ion-plating are reviewed. Their characteristics and potentials are discussed in terms of synthesis or deposition of tribological coatings. Since the glow discharge or plasma generated in the conventional sputtering and ion-plating techniques has a low ionization efficiency, rapid advances have been made in equipment design to further increase the ionization efficiency. The enhanced ionization favorably affects the nucleation and growth sequence of the coating. This leads to improved adherence and coherence, higher density, favorable morphological growth, and reduced internal stresses in the coatings. As a result, desirable coating characteristics can be precision tailored. Tribological coating characteristics of sputtered solid film lubricants such as MoS2, ion-plated soft gold and lead metallic films, and sputtered and ion-plated wear-resistant refractory compound films such as nitrides and carbides are discussed.

  10. Status of Plasma Physics Techniques for the Deposition of Tribological Coatings

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1984-01-01

    The plasma physics deposition techniques of sputtering and ion-plating are reviewed. Their characteristics and potentials are discussed in terms of synthesis or deposition of tribological coatings. Since the glow discharge or plasma generated in the conventional sputtering and ion-plating techniques has a low ionization efficiency, rapid advances have been made in equipment design to further increase the ionization efficiency. The enhanced ionization favorably affects the nucleation and growth sequence of the coating. This leads to improved adherence and coherence, higher density, favorable morphological growth, and reduced internal stresses in the coatings. As a result, desirable coating characteristics can be precision tailored. Tribological coating characteristics of sputtered solid film lubricants such as MoS2, ion-plated soft gold and lead metallic films, and sputtered and ion-plated wear-resistant refractory compound films such as nitrides and carbides are discussed.

  11. Nanofabrication using home-made RF plasma coupled chemical vapour deposition system

    NASA Astrophysics Data System (ADS)

    Ong, Si Ci; Ilyas, Usman; Rawat, Rajdeep Singh

    2014-08-01

    Zinc oxide, ZnO, a popular semiconductor material with a wide band gap (3.37 eV) and high binding energy of the exciton (60 meV), has numerous applications such as in optoelectronics, chemical/biological sensors, and drug delivery. This project aims to (i) optimize the operating conditions for growth of ZnO nanostructures using the chemical vapor deposition (CVD) method, and (ii) investigate the effects of coupling radiofrequency (RF) plasma to the CVD method on the quality of ZnO nanostructures. First, ZnO nanowires were synthesized using a home-made reaction setup on gold-coated and non-coated Si (100) substrates at 950 °C. XRD, SEM, EDX, and PL measurements were used for characterizations and it was found that a deposition duration of 10 minutes produced the most well-defined ZnO nanowires. SEM analysis revealed that the nanowires had diameters ranging from 30-100 mm and lengths ranging from 1-4 µm. In addition, PL analysis showed strong UV emission at 380 nm, making it suitable for UV lasing. Next, RF plasma was introduced for 30 minutes. Both remote and in situ RF plasma produced less satisfactory ZnO nanostructures with poorer crystalline structure, surface morphology, and optical properties due to etching effect of energetic ions produced from plasma. However, a reduction in plasma discharge duration to 10 minutes produced thicker and shorter ZnO nanostructures. Based on experimentation conducted, it is insufficient to conclude that RF plasma cannot aid in producing well-defined ZnO nanostructures. It can be deduced that the etching effect of energetic ions outweighed the increased oxygen radical production in RF plasma nanofabrication.

  12. Improved film quality of plasma enhanced atomic layer deposition SiO{sub 2} using plasma treatment cycle

    SciTech Connect

    Kim, Haiwon; Chung, Ilsub; Kim, Seokyun; Shin, Seungwoo; Jung, Wooduck; Hwang, Ryong; Jeong, Choonsik; Hwang, Hanna

    2015-01-15

    Chemical, physical, and electrical characteristics of high quality silicon dioxide (SiO{sub 2}) films grown using low temperature plasma enhanced atomic layer deposition (PE-ALD) have been investigated as a buffer layer for three dimensional vertical NAND flash memory devices. The comparative angle resolved x-ray photoelectron spectroscopy studies show the plasma treatment cycle causes to shift the core level binding energy (chemical shifts) in the SiO{sub 2} film. The wet etch rates with respect to plasma treatment cycle times were varied due to curing of the SiO{sub 2} network defects by Ar{sup +} ions and oxygen radicals. It is assumed that the angle between the bonds linking SiO{sub 4} tetrahedra is a critical point understanding the variation in wet etch rate of SiO{sub 2}. The features of wet etch rate of low temperature high quality SiO{sub 2} demonstrated lower than high temperature low-pressure chemical vapor deposition (LP-CVD) SiO{sub 2} values. In addition, the better step-coverage compared to that of the LP-CVD SiO{sub 2} film was achieved from the deep trench structure having the 20:1 aspect ratio. PE-ALD SiO{sub 2} with plasma treatment cycle showed excellent I–V properties with higher breakdown voltage compared to LP-CVD SiO{sub 2} and similar to the thermal SiO{sub 2} carrier transport plot.

  13. Plasma polymerization and deposition of linear, cyclic and aromatic fluorocarbons on (100)-oriented single crystal silicon substrates

    NASA Astrophysics Data System (ADS)

    Yang, G. H.; Oh, S. W.; Kang, E. T.; Neoh, K. G.

    2002-11-01

    Fluoropolymer films were deposited on the Ar plasma-pretreated Si(100) surfaces by plasma polymerization of perfluorohexane (PFH, a linear fluorocarbon), perfluoro(methylcyclohexane) (MCH, a cyclic fluorocarbon), and hexafluorobenzene (HFB, an aromatic fluorocarbon) under different glow discharge conditions. The effects of the radio-frequency plasma power on the chemical composition and structure of the plasma-polymerized fluoropolymer films were studied by x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry, and water contact angle measurements. The changes in structure and composition of the three types of the plasma-deposited films from those of the respective fluorocarbons were compared. Under similar glow discharge conditions: (i) the extent of defluorination was highest for the PFH polymer, (ii) the deposition rate was highest for the HFB polymer, (iii) the cyclic structure of MCH was less well preserved than the aromatic structure of HFB, (iv) aliphatic structures appeared in the plasma-deposited MCH polymer, and (v) the plasma-polymerized HFB has the highest thermal stability due to the preservation of the aromatic rings. The adhesive tape peel test results revealed that the plasma-polymerized and deposited fluoropolymer layers were strongly bonded to the Ar plasma-pretreated Si(100) surfaces.

  14. Characterization of TiO x film prepared by plasma enhanced chemical vapor deposition using a multi-jet hollow cathode plasma source

    NASA Astrophysics Data System (ADS)

    Nakamura, Masatoshi; Korzec, Dariusz; Aoki, Toru; Engemann, Jurgen; Hatanaka, Yoshinori

    2001-05-01

    The high rate deposition of TiO x film at low temperature was achieved by plasma enhanced chemical vapor deposition (PECVD) using titanium tetraisopropoxide (TTIP) as a source material. The multi-jet hollow cathode plasma source was used to generate the high-density plasma, which was showered toward the substrate. The emission spectra suggest that oxygen radicals play an important role for dissociation of the source material and for yielding the precursors. The high deposition rate up to 50 nm/min was achieved by this process. The as-deposited films are completely amorphous. They consist of structures with complex bondings including both tetrahedral and octahedral components. Though they have such complex bondings, the hydrophilicity of the PECVD film is excellent comparing to that of the annealed crystalline anatase structure. It seems that the PECVD using the multi-jet plasma source is promising for fabrication of hydrophilic TiO x films in low-temperature process.

  15. Nanotransfer Printing Using Plasma Etched Silicon Stamps and Mediated by In-Situ Deposited Fluoropolyme

    SciTech Connect

    Bhandari, Deepak; Kravchenko, Ivan I; Lavrik, Nickolay V; Sepaniak, Michael J

    2011-01-01

    This communication describes a simple method that uses a thin film of octafluorocyclobutane (OFCB) polymer for efficient nanoscale transfer printing (nTP). Plasma polymerization of OFCB produces a Teflon-like fluoropolymer which strongly adheres and conformally covers 3-D inorganic stamp. The inherently low surface energy of in-situ deposited OFCB polymer on nanoscale silicon features is demonstrated as a unique nanocomposite stamp to fabricate various test structures with improved nTP feature resolution down to sub 100 nm.

  16. Ion-substituted calcium phosphate coatings deposited by plasma-assisted techniques: A review.

    PubMed

    Graziani, Gabriela; Bianchi, Michele; Sassoni, Enrico; Russo, Alessandro; Marcacci, Maurilio

    2017-05-01

    One of the main critical aspects behind the failure or success of an implant resides in its ability to fast bond with the surrounding bone. To boost osseointegration, the ideal implant material should exhibit composition and structure similar to those of biological apatite. To this aim, the most common approach is to coat the implant surface with a coating of hydroxyapatite (HA), resembling the main component of mineralized tissues. However, bone apatite is a non-stoichiometric, multi-substituted poorly-crystalline apatite, containing significant amounts of foreign ions, with high biological relevance. Ion-substituted HAs can be deposited by so called "wet methods", which are however poorly reproducible and hardly industrially feasible; at the same time bioactive coatings realized by plasma assisted method, interesting for industrial applications, are generally made of stoichiometric (i.e. un-substituted) HA. In this work, the literature concerning plasma-assisted deposition methods used to deposit ion-substituted HA was reviewed and the last advances in this field discussed. The ions taken into exam are those present in mineralized tissues and possibly having biological relevance. Notably, literature about this topic is scarce, especially relating to in vivo animal and clinical trials; further on, available studies evaluate the performance of substituted coatings from different points of view (mechanical properties, bone growth, coating dissolution, etc.) which hinders a proper evaluation of the real efficacy of ion-doped HA in promoting bone regeneration, compared to stoichiometric HA. Moreover, results obtained for plasma sprayed coatings (which is the only method currently employed for deposition at the industrial scale) were collected and compared to those of novel plasma-assisted techniques, that are expected to overcome its limitations. Data so far available on the topic were discussed to highlight advantages, limitations and possible perspectives of these

  17. Solid oxide fuel cell electrolytes produced via very low pressure suspension plasma spray and electrophoretic deposition

    NASA Astrophysics Data System (ADS)

    Fleetwood, James D.

    Solid oxide fuel cells (SOFCs) are a promising element of comprehensive energy policies due to their direct mechanism for converting the oxidization of fuel, such as hydrogen, into electrical energy. Both very low pressure plasma spray and electrophoretic deposition allow working with high melting temperature SOFC suspension based feedstock on complex surfaces, such as in non-planar SOFC designs. Dense, thin electrolytes of ideal composition for SOFCs can be fabricated with each of these processes, while compositional control is achieved with dissolved dopant compounds that are incorporated into the coating during deposition. In the work reported, sub-micron 8 mole % Y2O3-ZrO2 (YSZ) and gadolinia-doped ceria (GDC), powders, including those in suspension with scandium-nitrate dopants, were deposited on NiO-YSZ anodes, via very low pressure suspension plasma spray (VLPSPS) at Sandia National Laboratories' Thermal Spray Research Laboratory and electrophoretic deposition (EPD) at Purdue University. Plasma spray was carried out in a chamber held at 320 - 1300 Pa, with the plasma composed of argon, hydrogen, and helium. EPD was characterized utilizing constant current deposition at 10 mm electrode separation, with deposits sintered from 1300 -- 1500 °C for 2 hours. The role of suspension constituents in EPD was analyzed based on a parametric study of powder loading, powder specific surface area, polyvinyl butyral (PVB) content, polyethyleneimine (PEI) content, and acetic acid content. Increasing PVB content and reduction of particle specific surface area were found to eliminate the formation of cracks when drying. PEI and acetic acid content were used to control suspension stability and the adhesion of deposits. Additionally, EPD was used to fabricate YSZ/GDC bilayer electrolyte systems. The resultant YSZ electrolytes were 2-27 microns thick and up to 97% dense. Electrolyte performance as part of a SOFC system with screen printed LSCF cathodes was evaluated with peak

  18. Device Quality SiO2 Deposited by Distributed Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition without Substrate Heating

    NASA Astrophysics Data System (ADS)

    Jiang, Nan; Hugon, Marie-Christine; Agius, Bernard; Kretz, Thierry; Plais, François; Pribat, Didier; Carriere, Thierry; Puech, Michel

    1992-10-01

    The deposition of high electrical quality SiO2 films on Si wafers has been achieved without substrate heating, (T<˜ 100°C), using distributed electron cyclotron resonance (DECR) microwave plasmas. We have studied the effects of the reactant gas mixture composition (O2/SiH4) on the dielectric behavior of DECR SiO2. The electrical performances of both Si-SiO2 interfaces and SiO2 films in metal-oxide-semiconductor (MOS) structures were assessed by several characterization methods including critical field (Ec) evaluation, fixed charge densities (Qox) and interface traps densities (Dit) determinations. We report typical values of Ec around 6 MV\\cdotcm-1, and Qox and Dit densities around 2× 1010 cm-2 and 3× 1010 cm-2\\cdoteV-1 respectively. Thin film SOI-MOSFETs have also been fabricated to prove the DECR oxide quality.

  19. The growth characteristics of microcrystalline Si thin film deposited by atmospheric pressure plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Kwon, Jung-Dae

    2013-11-01

    Microcrystalline silicon thin film was grown by atmospheric pressure plasma-enhanced chemical vapor deposition (AP-PECVD) technique with a cylindrical rotary electrode supplied with 150 MHz very-high-frequency power. The crystalline volume fraction could be controlled by changing the flow rate ratio of silane and hydrogen gas during AP-PECVD. We could also control it by regulating the substrate scanning speed. At low substrate scanning speed, the silicon film had a low crystalline volume faction and layer-by-layer structure with alternating layers of amorphous and microcrystalline Si. On the other hand, at high substrate scanning speed, silicon crystals of sizes 25 nm grew homogeneously throughout the whole film.

  20. Surface Passivation of ZrO2 Artificial Dentures by Magnetized Coaxial Plasma deposition

    NASA Astrophysics Data System (ADS)

    Arai, Soya; Kurumi, Satoshi; Matsuda, Ken-Ichi; Suzuki, Kaoru; Hara, Katsuya; Kato, Tatsuya; Asai, Tomohiko; Hirose, Hideharu; Masutani, Shigeyuki; Nihon University Team

    2015-09-01

    Recent growth and fabrication technologies for functional materials have been greatly contributed to drastic development of oral surgery field. Zirconia based ceramics is expected to utilize artificial dentures because these ceramics have good biocompatibility, high hardness and aesthetic attractively. However, to apply these ceramics to artificial dentures, this denture is removed from a dental plate because of weakly bond. For improving this problem, synthesis an Al passivation-layer on the ceramics for bonding with these dental items is suitable. In order to deposit the passivation layer, we focused on a magnetized coaxial plasma deposition (MCPD). The greatest characteristic of MCPD is that high-melting point metal can be deposited on various substrates. Additionally, adhesion force between substrate and films deposited by the MCPD is superior to it of general deposition methods. In this study, we have reported on the growth techniques of Al films on ZrO2 for contributing to oral surgery by the MCPD. Surface of deposited films shows there were some droplets and thickness of it is about 200 nm. Thickness is increased to 500 nm with increasing applied voltage.

  1. Low-temperature deposition of transparent diamond films with a microwave cavity plasma reactor

    NASA Astrophysics Data System (ADS)

    Ulczynski, Michael J.

    1998-10-01

    Low-temperature diamond deposition with Microwave Cavity Plasma Reactor (MCPR) technology was investigated for application to temperature sensitive substrates. The substrate temperature during most CVD diamond deposition processes is typically greater then 600 C; however, there are some applications where temperature sensitive materials are used and the deposition temperature must be maintained below 550 C. These applications include materials like boro-silicate glass, which has a relatively low strain-point temperature, and integrated circuits that contain low melting point components. Experiments were conducted in three areas. The first area was MCPR development, the second was benchmark deposition and characterization of diamond films on silicon substrates and the third was deposition and characterization of diamond films on boro-silicate glass substrates. MCPR development included an investigation of various MCPR configurations that were designed and adapted for uniform, low-temperature diamond deposition over areas as large as 80-cm2. Reactors were investigated with end-feed microwave excitation and side-feed microwave excitation for maximum deposition area and uniformity. Various substrate receptor configurations were also investigated including a substrate heater and cooler. From these investigations, deposition parameters such as substrate temperature, deposition rate, deposition area and deposition uniformity were characterized. The benchmark silicon diamond deposition experiments were conducted for comparison to previous high temperature, >550 C, MCPR research and growth models. Here deposition results such as deposition rate and film quality were compared with applications of diamond growth models by Harris-Goodwin and Bachmann. Additionally, characterization experiments were conducted to investigate film attributes that are critical to optical applications, such as film surface roughness and deposition uniformity. Included as variables in these

  2. Initiation of atomic layer deposition of metal oxides on polymer substrates by water plasma pretreatment

    SciTech Connect

    Steven Brandt, E.; Grace, Jeremy M.

    2012-01-15

    The role of surface hydroxyl content in atomic layer deposition (ALD) of aluminum oxide (AO) on polymers is demonstrated by performing an atomic layer deposition of AO onto a variety of polymer types, before and after pretreatment in a plasma struck in water vapor. The treatment and deposition reactions are performed in situ in a high vacuum chamber that is interfaced to an x-ray photoelectron spectrometer to prevent adventitious exposure to atmospheric contaminants. X-ray photoelectron spectroscopy is used to follow the surface chemistries of the polymers, including theformation of surface hydroxyls and subsequent growth of AO by ALD. Using dimethyl aluminum isopropoxide and water as reactants, ALD is obtained for water-plasma-treated poly(styrene) (PS), poly(propylene) (PP), poly(vinyl alcohol) (PVA), and poly(ethylene naphthalate) (PEN). For PS, PP, and PEN, initial growth rates of AO on the native (untreated) polymers are at least an order of magnitude lower than on the same polymer surface following the plasma treatment. By contrast, native PVA is shown to initiate ALD of AO as a result of the presence of intrinsic surface hydroxyls that are derived from the repeat unit of this polymer.

  3. Distinctive features of kinetics of plasma at high specific energy deposition

    NASA Astrophysics Data System (ADS)

    Lepikhin, Nikita; Popov, Nikolay; Starikovskaia, Svetlana

    2016-09-01

    A nanosecond capillary discharge in pure nitrogen at moderate pressures is used as an experimental tool for plasma kinetics studies at conditions of high specific deposited energy up to 1 eV/molecule. Experimental observations based on electrical (back current shunts, capacitive probe) and spectroscopic measurements (quenching rates; translational, rotational and vibrational temperature measurements) demonstrate that high specific deposited energy, at electric fields of 200-300 Td, can significantly change gas kinetics in the discharge and in the afterglow. The numerical calculations in 1D axially symmetric geometry using experimental data as input parameters show that changes in the plasma kinetics are caused by extremely high excitation degree: up to 10% of molecular nitrogen is electronically excited at present conditions. Distinctive features of kinetics of plasma at high specific energy deposition as well as details of the experimental technique and numerical calculations will be present. The work was partially supported by French National Agency, ANR (PLASMAFLAME Project, 2011 BS09 025 01), AOARD AFOSR, FA2386-13-1-4064 grant (Program Officer Prof. Chiping Li), LabEx Plas@Par and Linked International Laboratory LIA KaPPA (France-Russia).

  4. Low Temperature Metal Free Growth of Graphene on Insulating Substrates by Plasma Assisted Chemical Vapor Deposition.

    PubMed

    Muñoz, R; Munuera, C; Martínez, J I; Azpeitia, J; Gómez-Aleixandre, C; García-Hernández, M

    2017-03-01

    Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650°C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω·sq(-1). The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies.

  5. Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography

    NASA Astrophysics Data System (ADS)

    Liu, Zhengjun; Shah, Ali; Alasaarela, Tapani; Chekurov, Nikolai; Savin, Hele; Tittonen, Ilkka

    2017-02-01

    In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga+ ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90-210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16:1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

  6. Low temperature metal free growth of graphene on insulating substrates by plasma assisted chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Muñoz, R.; Munuera, C.; Martínez, J. I.; Azpeitia, J.; Gómez-Aleixandre, C.; García-Hernández, M.

    2017-03-01

    Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650 °C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω sq-1. The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies.

  7. Silicon dioxide mask by plasma enhanced atomic layer deposition in focused ion beam lithography.

    PubMed

    Liu, Zhengjun; Shah, Ali; Alasaarela, Tapani; Chekurov, Nikolai; Savin, Hele; Tittonen, Ilkka

    2017-02-24

    In this work, focused ion beam (FIB) lithography was developed for plasma enhanced atomic layer deposited (PEALD) silicon dioxide SiO2 hard mask. The PEALD process greatly decreases the deposition temperature of the SiO2 hard mask. FIB Ga(+) ion implantation on the deposited SiO2 layer increases the wet etch resistivity of the irradiated region. A programmed exposure in FIB followed by development in a wet etchant enables the precisely defined nanoscale patterning. The combination of FIB exposure parameters and the development time provides greater freedom for optimization. The developed process provides high pattern dimension accuracy over the tested range of 90-210 nm. Utilizing the SiO2 mask developed in this work, silicon nanopillars with 40 nm diameter were successfully fabricated with cryogenic deep reactive ion etching and the aspect ratio reached 16:1. The fabricated mask is suitable for sub-100 nm high aspect ratio silicon structure fabrication.

  8. Electron cyclotron resonance plasma deposition of silicon nitride: Effect of very low rf substrate bias

    NASA Astrophysics Data System (ADS)

    Buckle, K. A.; Rodgers, J.; Pastor, K.; Constantine, C.; Johnson, D.

    1992-05-01

    Plasma deposition of SiN on silicon substrates in a microwave (2.45 GHz) electron cyclotron resonance SiH4/N2/He, in the ratio 4/10/10, discharge has been investigated as a function of rf (40 MHz) self-biasing of the sample. Low levels of rf bias (0-10 W) were investigated and are reported in this letter. The effect of bias was measured for the deposited films with respect to refractive index, etch rate in BHF, Si—H bonding, and the intrinsic film stress. All depositions were conducted at or near room temperature to evaluate the effect of the applied rf bias on film density. All parameters examined indicated that low levels of rf bias help prepare a high quality, dense film at very low substrate temperatures.

  9. Low Temperature Metal Free Growth of Graphene on Insulating Substrates by Plasma Assisted Chemical Vapor Deposition

    PubMed Central

    Muñoz, R.; Munuera, C.; Martínez, J. I.; Azpeitia, J.; Gómez-Aleixandre, C.; García-Hernández, M.

    2016-01-01

    Direct growth of graphene films on dielectric substrates (quartz and silica) is reported, by means of remote electron cyclotron resonance plasma assisted chemical vapor deposition r-(ECR-CVD) at low temperature (650°C). Using a two step deposition process- nucleation and growth- by changing the partial pressure of the gas precursors at constant temperature, mostly monolayer continuous films, with grain sizes up to 500 nm are grown, exhibiting transmittance larger than 92% and sheet resistance as low as 900 Ω·sq-1. The grain size and nucleation density of the resulting graphene sheets can be controlled varying the deposition time and pressure. In additon, first-principles DFT-based calculations have been carried out in order to rationalize the oxygen reduction in the quartz surface experimentally observed. This method is easily scalable and avoids damaging and expensive transfer steps of graphene films, improving compatibility with current fabrication technologies. PMID:28070341

  10. Deposition of zinc oxide photoelectrode using plasma enhanced chemical vapor deposition for dye-sensitized solar cells.

    PubMed

    Lee, Su Young; Kim, Sang Ho

    2014-12-01

    We investigated the characteristics of zinc oxide (ZnO) photoelectrodes grown by plasma enhanced chemical vapor deposition. ZnO has many advantages, such as high binding energy, breakdown strength, cohesion, hardness, and electron mobility. On the F-doped SnO2 (FTO) electrode, we deposited ZnO as a function of thickness, and we examined the thickness effect on the I-V, fill factor, open-circuit voltage, short-circuit current density, and especially the power conversion efficiency of the built in dye-sensitized solar cell. To study the thickness effect on the conduction and recombination of electrons in the ZnO electrode, we analyzed the alignment of grains, crystallinity, impedance, and cyclic I-V properties. The thickness of ZnO changed the electron diffusion length and recombination time. As a result, the maximum power conversion efficiency of 2.63% was obtained with a moderately thick (8.06 μm) ZnO.

  11. Characteristics of nanocomposite ZrO2/Al2O3 films deposited by plasma-enhanced atomic layer deposition.

    PubMed

    Yun, Sun Jin; Lim, Jung Wook; Kim, Hyun-Tak

    2007-11-01

    Nanocomposite ZrO2/Al2O3 (ZAO) films were deposited on Si by plasma-enhanced atomic layer deposition and the film characteristics including interfacial oxide formation, dielectric constant (k), and electrical breakdown strength were investigated without post-annealing process. In both the mixed and nano-laminated ZAO films, the thickness of the interfacial oxide layer (T(IL)) was considerably reduced compared to ZrO2 and Al2O3 films. The T(IL) was 0.8 nm in nano-composite films prepared at a mixing ratio (ZrO2:Al2O3) of 1:1. The breakdown strength and the leakage current level were greatly improved by adding Al2O3 as little as 7.9% compared to that of ZrO2 and were enhanced more with increasing content of Al2O3. The k of ZrO2 and mixed ZAO (Al2O3 7.9%) films were 20.0 and 16.5, respectively. These results indicate that the addition of Al2O3 to ZrO2 greatly improves the electrical properties with less cost of k compared to the addition of SiO2.

  12. Uniform Atomic Layer Deposition of Al2O3 on Graphene by Reversible Hydrogen Plasma Functionalization

    PubMed Central

    2017-01-01

    A novel method to form ultrathin, uniform Al2O3 layers on graphene using reversible hydrogen plasma functionalization followed by atomic layer deposition (ALD) is presented. ALD on pristine graphene is known to be a challenge due to the absence of dangling bonds, leading to nonuniform film coverage. We show that hydrogen plasma functionalization of graphene leads to uniform ALD of closed Al2O3 films down to 8 nm in thickness. Hall measurements and Raman spectroscopy reveal that the hydrogen plasma functionalization is reversible upon Al2O3 ALD and subsequent annealing at 400 °C and in this way does not deteriorate the graphene’s charge carrier mobility. This is in contrast with oxygen plasma functionalization, which can lead to a uniform 5 nm thick closed film, but which is not reversible and leads to a reduction of the charge carrier mobility. Density functional theory (DFT) calculations attribute the uniform growth on both H2 and O2 plasma functionalized graphene to the enhanced adsorption of trimethylaluminum (TMA) on these surfaces. A DFT analysis of the possible reaction pathways for TMA precursor adsorption on hydrogenated graphene predicts a binding mechanism that cleans off the hydrogen functionalities from the surface, which explains the observed reversibility of the hydrogen plasma functionalization upon Al2O3 ALD. PMID:28405059

  13. Disilane as a growth rate catalyst of plasma deposited microcrystalline silicon thin films

    NASA Astrophysics Data System (ADS)

    Dimitrakellis, P.; Kalampounias, A. G.; Spiliopoulos, N.; Amanatides, E.; Mataras, D.; Lahootun, V.; Coeuret, F.; Madec, A.

    2016-07-01

    The effect of small disilane addition on the gas phase properties of silane-hydrogen plasmas and the microcrystalline silicon thin films growth is presented. The investigation was conducted in the high pressure regime and for constant power dissipation in the discharge with the support of plasma diagnostics, thin film studies and calculations of discharge microscopic parameters and gas dissociation rates. The experimental data and the calculations show a strong effect of disilane on the electrical properties of the discharge in the pressure window from 2 to 3 Torr that is followed by significant raise of the electron number density and the drop of the sheaths electric field intensity. Deposition rate measurements show an important four to six times increase even for disilane mole fractions as low as 0.3 %. The deposition rate enhancement was followed by a drop of the material crystalline volume fraction but films with crystallinity above 40 % were deposited with different combinations of total gas pressure, disilane and silane molar ratios. The enhancement was partly explained by the increase of the electron impact dissociation rate of silane which rises by 40% even for 0.1% disilane mole fraction. The calculations of the gas usage, the dissociation and the deposition efficiencies show that the beneficial effect on the growth rate is not just the result of the increase of Si-containing molecules density but significant changes on the species participating to the deposition and the mechanism of the film growth are caused by the disilane addition. The enhanced participation of the highly sticking to the surface radical such as disilylene, which is the main product of disilane dissociation, was considered as the most probable reason for the significant raise of the deposition efficiency. The catalytic effect of such type of radical on the surface reactivity of species with lower sticking probability is further discussed, while it is also used to explain the restricted

  14. Disilane as a growth rate catalyst of plasma deposited microcrystalline silicon thin films

    SciTech Connect

    Dimitrakellis, P.; Amanatides, E. Mataras, D.; Kalampounias, A. G.; Spiliopoulos, N.; Lahootun, V.; Coeuret, F.; Madec, A.

    2016-07-15

    The effect of small disilane addition on the gas phase properties of silane-hydrogen plasmas and the microcrystalline silicon thin films growth is presented. The investigation was conducted in the high pressure regime and for constant power dissipation in the discharge with the support of plasma diagnostics, thin film studies and calculations of discharge microscopic parameters and gas dissociation rates. The experimental data and the calculations show a strong effect of disilane on the electrical properties of the discharge in the pressure window from 2 to 3 Torr that is followed by significant raise of the electron number density and the drop of the sheaths electric field intensity. Deposition rate measurements show an important four to six times increase even for disilane mole fractions as low as 0.3 %. The deposition rate enhancement was followed by a drop of the material crystalline volume fraction but films with crystallinity above 40 % were deposited with different combinations of total gas pressure, disilane and silane molar ratios. The enhancement was partly explained by the increase of the electron impact dissociation rate of silane which rises by 40% even for 0.1% disilane mole fraction. The calculations of the gas usage, the dissociation and the deposition efficiencies show that the beneficial effect on the growth rate is not just the result of the increase of Si-containing molecules density but significant changes on the species participating to the deposition and the mechanism of the film growth are caused by the disilane addition. The enhanced participation of the highly sticking to the surface radical such as disilylene, which is the main product of disilane dissociation, was considered as the most probable reason for the significant raise of the deposition efficiency. The catalytic effect of such type of radical on the surface reactivity of species with lower sticking probability is further discussed, while it is also used to explain the restricted

  15. Fourth-generation plasma immersion ion implantation and deposition facility for hybrid surface modification layer fabrication

    SciTech Connect

    Wang Langping; Huang Lei; Xie Zhiwen; Wang Xiaofeng; Tang Baoyin

    2008-02-15

    The fourth-generation plasma immersion ion implantation and deposition (PIIID) facility for hybrid and batch treatment was built in our laboratory recently. Comparing with our previous PIIID facilities, several novel designs are utilized. Two multicathode pulsed cathodic arc plasma sources are fixed on the chamber wall symmetrically, which can increase the steady working time from 6 h (the single cathode source in our previous facilities) to about 18 h. Meanwhile, the inner diameter of the pulsed cathodic arc plasma source is increased from the previous 80 to 209 mm, thus, large area metal plasma can be obtained by the source. Instead of the simple sample holder in our previous facility, a complex revolution-rotation sample holder composed of 24 shafts, which can rotate around its axis and adjust its position through revolving around the center axis of the vacuum chamber, is fixed in the center of the vacuum chamber. In addition, one magnetron sputtering source is set on the chamber wall instead of the top cover in the previous facility. Because of the above characteristic, the PIIID hybrid process involving ion implantation, vacuum arc, and magnetron sputtering deposition can be acquired without breaking vacuum. In addition, the PIIID batch treatment of cylinderlike components can be finished by installing these components on the rotating shafts on the sample holder.

  16. Deposition of silicon dioxide films with a non-equilibrium atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Babayan, S. E.; Jeong, J. Y.; Schütze, A.; Tu, V. J.; Moravej, Maryam; Selwyn, G. S.; Hicks, R. F.

    2001-11-01

    Silicon dioxide films were grown using an atmospheric-pressure plasma jet that was produced by flowing oxygen and helium between two coaxial metal electrodes that were driven by 13.56 MHz radio frequency power. The plasma exiting from between the electrodes was mixed with tetraethoxysilane (TEOS), and directed onto a silicon substrate held at 115-350 °C. Silicon dioxide films were deposited at rates ranging from 20±2 to 300±25 nm min-1. The deposition rate increased with decreasing temperature and increasing TEOS pressure, oxygen pressure and RF power. For the latter two variables, the rate increased as follows: Rd∝P0.3O2(RF)1.4. Films grown at 115 °C were porous and contained adsorbed hydroxyl groups, whereas films grown at 350 °C were smooth, dense and free of impurities. These results suggest that the mechanism in the atmospheric pressure plasma is the same as that in low-pressure plasmas.

  17. Inhibition of Crystal Growth during Plasma Enhanced Atomic Layer Deposition by Applying BIAS

    PubMed Central

    Ratzsch, Stephan; Kley, Ernst-Bernhard; Tünnermann, Andreas; Szeghalmi, Adriana

    2015-01-01

    In this study, the influence of direct current (DC) biasing on the growth of titanium dioxide (TiO2) layers and their nucleation behavior has been investigated. Titania films were prepared by plasma enhanced atomic layer deposition (PEALD) using Ti(OiPr)4 as metal organic precursor. Oxygen plasma, provided by remote inductively coupled plasma, was used as an oxygen source. The TiO2 films were deposited with and without DC biasing. A strong dependence of the applied voltage on the formation of crystallites in the TiO2 layer is shown. These crystallites form spherical hillocks on the surface which causes high surface roughness. By applying a higher voltage than the plasma potential no hillock appears on the surface. Based on these results, it seems likely, that ions are responsible for the nucleation and hillock growth. Hence, the hillock formation can be controlled by controlling the ion energy and ion flux. The growth per cycle remains unchanged, whereas the refractive index slightly decreases in the absence of energetic oxygen ions. PMID:28793679

  18. Plasma deposition of tetraglyme inside small diameter tubing: optimization and characterization.

    PubMed

    Cao, Lan; Ratner, Buddy D; Horbett, Thomas A

    2007-04-01

    In this study, a glow discharge plasma deposition system previously used for treating flat substrates was successfully modified and optimized to produce a PEO-like coating on the inner surface of 1-3 mm ID polyethylene tubing by deposition of tetra ethylene glycol dimethyl ether (tetraglyme). The plasma treatment conditions were varied in order to find operating values that would produce coatings with the ultralow (< 5 ng/cm(2)) fibrinogen adsorption (Gamma(Fg)) previously shown necessary to significantly reduce platelet adhesion. The flow rate of gaseous tetraglyme monomer, pressure, and plasma generating power were found to be the most important parameters affecting the uniformity and chemical structure of the coating. The coating uniformity and quality were assessed by measuring Gamma(Fg) at positions 1 cm apart along the entire tube and the fraction of C1s carbon that was in an ether bond (ether-carbon ratio) by electron spectroscopy of chemical analysis. Under optimized conditions, tetraglyme plasma-coated tubes of up to 20 cm in length had ultralow Gamma(Fg). The region of the tube that had ultralow Gamma(Fg) also had C1s ether-carbon ratios that are greater than 50%. (c) 2006 Wiley Periodicals, Inc.

  19. Atmospheric pressure plasma deposition of antimicrobial coatings on non-woven textiles

    NASA Astrophysics Data System (ADS)

    Nikiforov, Anton Yu.; Deng, Xiaolong; Onyshchenko, Iuliia; Vujosevic, Danijela; Vuksanovic, Vineta; Cvelbar, Uros; De Geyter, Nathalie; Morent, Rino; Leys, Christophe

    2016-08-01

    A simple method for preparation of nanoparticle incorporated non-woven fabric with high antibacterial efficiency has been proposed based on atmospheric pressure plasma process. In this work direct current plasma jet stabilized by fast nitrogen flow was used as a plasma deposition source. Three different types of the nanoparticles (silver, copper and zinc oxide nanoparticles) were employed as antimicrobial agents. X-ray photoelectron spectroscopy (XPS) measurements have shown a positive chemical shift observed for Ag 3d 5/2 (at 368.1 eV) suggests that silver nanoparticles (AgNPs) are partly oxidized during the deposition. The surface chemistry and the antibacterial activity of the samples against Staphylococcus aureus and Escherichia coli were investigated and analyzed. It is shown that the samples loaded with nanoparticles of Ag and Cu and having the barrier layer of 10 nm characterized by almost 97% of bacterial reduction whereas the samples with ZnO nanoparticles provide 86% reduction of Staphylococcus aureus. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  20. Permeation mechanisms of pulsed microwave plasma deposited silicon oxide films for food packaging applications

    NASA Astrophysics Data System (ADS)

    Deilmann, Michael; Grabowski, Mirko; Theiß, Sebastian; Bibinov, Nikita; Awakowicz, Peter

    2008-07-01

    Silicon oxide barrier layers are deposited on polyethylene terephthalate as permeation barriers for food packaging applications by means of a low pressure microwave plasma. Hexamethyldisiloxane (HMDSO) and oxygen are used as process gases to deposit SiOx coatings via pulsed low pressure plasmas. The layer composition of the coating is investigated by Fourier transform infrared spectroscopy and energy dispersive x-ray spectroscopy to show correlations with barrier properties of the films. The oxygen permeation barrier is determined by the carrier gas method using an electrochemical detector. The transition from low to high barrier films is mapped by the transition from organic SiOxCyHz layers to quartz-like SiO1.7 films containing silanol bound hydrogen. A residual permeation as low as J = 1 ± 0.3 cm3 m-2 day-1 bar-1 is achieved, which is a good value for food packaging applications. Additionally, the activation energy Ep of oxygen permeation is analysed and a strong increase from Ep = 31.5 kJ mol-1 for SiOx CyHz-like coatings to Ep = 53.7 kJ mol-1 for SiO1.7 films is observed by increasing the oxygen dilution of HMDSO:O2 plasma. The reason for the residual permeation of high barrier films is discussed and coating defects are visualized by capacitively coupled atomic oxygen plasma etching of coated substrates. A defect density of 3000 mm-2 is revealed.

  1. Characterizations of GaN film growth by ECR plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Fu, Silie; Chen, Junfang; Zhang, Hongbin; Guo, Chaofen; Li, Wei; Zhao, Wenfen

    2009-06-01

    The electron cyclotron resonance plasma-enhanced metalorganic chemical vapor deposition technology (ECR-MOPECVD) is adopted to grow GaN films on (0 0 0 1) α-Al2O3 substrate. The gas sources are pure N2 and trimethylgallium (TMG). Optical emission spectroscopy (OES) and thermodynamic analysis of GaN growth are applied to understand the GaN growth process. The OES of ECR plasma shows that TMG is significantly dissociated in ECR plasma. Reactants N and Ga in the plasma, obtained easily under the self-heating condition, are essential for the GaN growth. They contribute to the realization of GaN film growth at a relatively low temperature. The thermodynamic study shows that the driving force for the GaN growth is high when N2:TMG>1. Furthermore, higher N2:TMG flow ratio makes the GaN growth easier. Finally, X-ray diffraction, photoluminescence, and atomic force microscope are applied to investigate crystal quality, morphology, and roughness of the GaN films. The results demonstrate that the ECR-MOPECVD technology is favorable for depositing GaN films at low temperatures.

  2. Improvement of the thermal stability of nickel silicide using a ruthenium interlayer deposited via remote plasma atomic layer deposition

    SciTech Connect

    Lee, Inhye; Park, Jingyu; Jeon, Heeyoung; Kim, Hyunjung; Shin, Changhee; Shin, Seokyoon; Lee, Kunyoung; Jeon, Hyeongtag

    2016-05-15

    In this study, the effects of a thin Ru interlayer on the thermal and morphological stability of NiSi have been investigated. Ru and Ni thin films were deposited sequentially to form a Ni/Ru/Si bilayered structure, without breaking the vacuum, by remote plasma atomic layer deposition (RPALD) on a p-type Si wafer. After annealing at various temperatures, the thermal stabilities of the Ni/Ru/Si and Ni/Si structures were investigated by various analysis techniques. The results showed that the sheet resistance of the Ni/Ru/Si sample was consistently lower compared to the Ni/Si sample over the entire temperature range. Although both samples exhibited the formation of NiSi{sub 2} phases at an annealing temperature of 800 °C, as seen with glancing angle x-ray diffraction, the peaks of the Ni/Ru/Si sample were observed to have much weaker intensities than those obtained for the Ni/Si sample. Moreover, the NiSi film with a Ru interlayer exhibited a better interface and improved surface morphologies compared to the NiSi film without a Ru interlayer. These results show that the phase transformation of NiSi to NiSi{sub 2} was retarded and that the smooth NiSi/Si interface was retained due to the activation energy increment for NiSi{sub 2} nucleation that is caused by adding a Ru interlayer. Hence, it can be said that the Ru interlayer deposited by RPALD can be used to control the phase transformation and physical properties of nickel silicide phases.

  3. Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

    SciTech Connect

    Demaurex, Bénédicte Bartlome, Richard; Seif, Johannes P.; Geissbühler, Jonas; Ballif, Christophe; De Wolf, Stefaan; Alexander, Duncan T. L.; Jeangros, Quentin

    2014-08-07

    Low-temperature (≤200 °C) epitaxial growth yields precise thickness, doping, and thermal-budget control, which enables advanced-design semiconductor devices. In this paper, we use plasma-enhanced chemical vapor deposition to grow homo-epitaxial layers and study the different growth modes on crystalline silicon substrates. In particular, we determine the conditions leading to epitaxial growth in light of a model that depends only on the silane concentration in the plasma and the mean free path length of surface adatoms. For such growth, we show that the presence of a persistent defective interface layer between the crystalline silicon substrate and the epitaxial layer stems not only from the growth conditions but also from unintentional contamination of the reactor. Based on our findings, we determine the plasma conditions to grow high-quality bulk epitaxial films and propose a two-step growth process to obtain device-grade material.

  4. Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

    SciTech Connect

    Demaurex, Bénédicte; Bartlome, Richard; Seif, Johannes P.; Geissbühler, Jonas; Alexander, Duncan T. L.; Jeangros, Quentin; Ballif, Christophe; De Wolf, Stefaan

    2014-08-05

    Low-temperature (≤ 180 °C) epitaxial growth yields precise thickness, doping, and thermal-budget control, which enables advanced-design semiconductor devices. In this paper, we use plasma-ehanced chemical vapor deposition to grow homo-epitaxial layers and study the different growth modes on crystalline silicon substrates. In particular, we determine the conditions leading to epitaxial growth in light of a model that depends only on the silane concentration in the plasma and the mean free path length of surface adatoms. For such growth, we show that the presence of a persistent defective interface layer between the crystalline silicon substrate and the epitaxial layer stems not only from the growth conditions but also from unintentional contamination of the reactor. As a result of our findings, we determine the plasma conditions to grow high-quality bulk epitaxial films and propose a two-step growth process to obtain device-grade material.

  5. Plasma treatment process for palladium chemisorption onto polymers before electroless deposition

    SciTech Connect

    Charbonnier, M.; Alami, M.; Romand, M.

    1996-02-01

    Before electroless plating, polymer surfaces must be sensitized and/or activated by using either the conventional two-step or one-step process. The latter stage is a compulsory one to make such surfaces catalytic, e.g., for Ni-P deposition. These processes are performed here using O{sub 2}, NH{sub 3}, or N{sub 2} plasma pretreatments. Reaction mechanisms are proposed for each of the processes and for each type of surface considered (oxygenated or both oxygenated and nitrogenated by the plasma treatment). Direct palladium chemisorption onto nitrogenated groups is highlighted. This allows one to simplify the process making the surface catalytic via elimination of the use of SnCl{sub 2} and to extend the method to any polymer. An additional interest of the plasma treatments, besides their high efficiency in grafting chemical functions, is to perform this grafting at will on selected areas which results in selective metallization.

  6. Plasma-enhanced atomic layer deposition of titanium oxynitrides films: A comparative spectroscopic and electrical study

    SciTech Connect

    Sowińska, Małgorzata Henkel, Karsten; Schmeißer, Dieter; Kärkkänen, Irina; Schneidewind, Jessica; Naumann, Franziska; Gruska, Bernd; Gargouri, Hassan

    2016-01-15

    The process parameters' impact of the plasma-enhanced atomic layer deposition (PE-ALD) method on the oxygen to nitrogen (O/N) ratio in titanium oxynitride (TiO{sub x}N{sub y}) films was studied. Titanium(IV)isopropoxide in combination with NH{sub 3} plasma and tetrakis(dimethylamino)titanium by applying N{sub 2} plasma processes were investigated. Samples were characterized by the in situ spectroscopic ellipsometry, x-ray photoelectron spectroscopy, and electrical characterization (current–voltage: I-V and capacitance–voltage: C-V) methods. The O/N ratio in the TiO{sub x}N{sub y} films is found to be very sensitive for their electric properties such as conductivity, dielectric breakdown, and permittivity. Our results indicate that these PE-ALD film properties can be tuned, via the O/N ratio, by the selection of the process parameters and precursor/coreactant combination.

  7. Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF{sub 6} based plasmas

    SciTech Connect

    Perros, Alexander; Bosund, Markus; Sajavaara, Timo; Laitinen, Mikko; Sainiemi, Lauri; Huhtio, Teppo; Lipsanen, Harri

    2012-01-15

    The plasma etch characteristics of aluminum nitride (AlN) deposited by low-temperature, 200 deg. C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF{sub 6} and O{sub 2} under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film's removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film removal because the film was inert to the SF{sub x}{sup +} and O{sup +} chemistries. The etch experiments showed the film to be a resilient masking material. This makes it an attractive candidate for use as an etch mask in demanding SF{sub 6} based plasma etch applications, such as through-wafer etching, or when oxide films are not suitable.

  8. Effect of Gas Sources on the Deposition of Nano-Crystalline Diamond Films Prepared by Microwave Plasma Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Weng, Jun; Xiong, Liwei; Wang, Jianhua; Man, Weidong; Chen, Guanhu

    2010-12-01

    Nano-crystalline diamond (NCD) films were deposited on silicon substrates by a microwave plasma enhanced chemical vapor deposition (MPCVD) reactor in C2H5OH/H2 and CH4/H2/O2 systems, respectively, with a constant ratio of carbon/hydrogen/oxygen. By means of atomic force microscopy (AFM) and X-ray diffraction (XRD), it was shown that the NCD films deposited in the C2H5OH/H2 system possesses more uniform surface than that deposited in the CH4/H2/O2 system. Results from micro-Raman spectroscopy revealed that the quality of the NCD films was different even though the plasmas in the two systems contain exactly the same proportion of elements. In order to explain this phenomenon, the bond energy of forming OH groups, energy distraction in plasma and the deposition process of NCD films were studied. The experimental results and discussion indicate that for a same ratio of carbon/hydrogen/oxygen, the C2H5OH/H2 plasma was beneficial to deposit high quality NCD films with smaller average grain size and lower surface roughness.

  9. Plasma parameters of pulsed-dc discharges in methane used to deposit diamondlike carbon films

    SciTech Connect

    Corbella, C.; Rubio-Roy, M.; Bertran, E.; Andujar, J. L.

    2009-08-01

    Here we approximate the plasma kinetics responsible for diamondlike carbon (DLC) depositions that result from pulsed-dc discharges. The DLC films were deposited at room temperature by plasma-enhanced chemical vapor deposition (PECVD) in a methane (CH{sub 4}) atmosphere at 10 Pa. We compared the plasma characteristics of asymmetric bipolar pulsed-dc discharges at 100 kHz to those produced by a radio frequency (rf) source. The electrical discharges were monitored by a computer-controlled Langmuir probe operating in time-resolved mode. The acquisition system provided the intensity-voltage (I-V) characteristics with a time resolution of 1 mus. This facilitated the discussion of the variation in plasma parameters within a pulse cycle as a function of the pulse waveform and the peak voltage. The electron distribution was clearly divided into high- and low-energy Maxwellian populations of electrons (a bi-Maxwellian population) at the beginning of the negative voltage region of the pulse. We ascribe this to intense stochastic heating due to the rapid advancing of the sheath edge. The hot population had an electron temperature T{sub e}{sup hot} of over 10 eV and an initial low density n{sub e}{sup hot} which decreased to zero. Cold electrons of temperature T{sub e}{sup cold}approx1 eV represented the majority of each discharge. The density of cold electrons n{sub e}{sup cold} showed a monotonic increase over time within the negative pulse, peaking at almost 7x10{sup 10} cm{sup -3}, corresponding to the cooling of the hot electrons. The plasma potential V{sub p} of approx30 V underwent a smooth increase during the pulse and fell at the end of the negative region. Different rates of CH{sub 4} conversion were calculated from the DLC deposition rate. These were explained in terms of the specific activation energy E{sub a} and the conversion factor x{sub dep} associated with the plasma processes. The work deepens our understanding of the advantages of using pulsed power supplies

  10. Plasma-enhanced deposition of antifouling layers on silicone rubber surfaces

    NASA Astrophysics Data System (ADS)

    Jiang, Hongquan

    In food processing and medical environments, biofilms serve as potential sources of contamination, and lead to food spoilage, transmission of diseases or infections. Because of its ubiquitous and recalcitrant nature, Listeria monocytogenes biofilm is especially hard to control. Generating antimicrobial surfaces provide a method to control the bacterial attachment. The difficulty of silver deposition on polymeric surfaces has been overcome by using a unique two-step plasma-mediated method. First silicone rubber surfaces were plasma-functionalized to generate aldehyde groups. Then thin silver layers were deposited onto the functionalized surfaces according to Tollen's reaction. X-ray photoelectron spectroscopy (XPS), atomic force spectroscopy (AFM) and scanning electron microscopy (SEM) showed that silver particles were deposited. By exposing the silver coated surfaces to L. monocytogenes, it was demonstrated that they were bactericidal to L. monocytogenes. No viable bacteria were detected after 12 to 18 h on silver-coated silicone rubber surfaces. Another antifouling approach is to generate polyethylene glycol (PEG) thin layer instead of silver on polymer surfaces. Covalent bond of PEG structures of various molecular weights to cold-plasma-functionalized polymer surfaces, such as silicone rubber, opens up a novel way for the generation of PEG brush-like or PEG branch-like anti-fouling layers. In this study, plasma-generated surface free radicals can react efficiently with dichlorosilane right after plasma treatment. With the generation of halo-silane groups, this enables PEG molecules to be grafted onto the modified surfaces. XPS data clearly demonstrated the presence of PEG molecules on plasma-functionalized silicone rubber surfaces. AFM images showed the changed surface morphologies as a result of covalent attachment to the surface of PEG molecules. Biofilm experiment results suggest that the PEG brush-like films have the potential ability to be the next

  11. Low-Temperature Plasma-Assisted Atomic Layer Deposition of Silicon Nitride Moisture Permeation Barrier Layers.

    PubMed

    Andringa, Anne-Marije; Perrotta, Alberto; de Peuter, Koen; Knoops, Harm C M; Kessels, Wilhelmus M M; Creatore, Mariadriana

    2015-10-14

    Encapsulation of organic (opto-)electronic devices, such as organic light-emitting diodes (OLEDs), photovoltaic cells, and field-effect transistors, is required to minimize device degradation induced by moisture and oxygen ingress. SiNx moisture permeation barriers have been fabricated using a very recently developed low-temperature plasma-assisted atomic layer deposition (ALD) approach, consisting of half-reactions of the substrate with the precursor SiH2(NH(t)Bu)2 and with N2-fed plasma. The deposited films have been characterized in terms of their refractive index and chemical composition by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The SiNx thin-film refractive index ranges from 1.80 to 1.90 for films deposited at 80 °C up to 200 °C, respectively, and the C, O, and H impurity levels decrease when the deposition temperature increases. The relative open porosity content of the layers has been studied by means of multisolvent ellipsometric porosimetry (EP), adopting three solvents with different kinetic diameters: water (∼0.3 nm), ethanol (∼0.4 nm), and toluene (∼0.6 nm). Irrespective of the deposition temperature, and hence the impurity content in the SiNx films, no uptake of any adsorptive has been observed, pointing to the absence of open pores larger than 0.3 nm in diameter. Instead, multilayer development has been observed, leading to type II isotherms that, according to the IUPAC classification, are characteristic of nonporous layers. The calcium test has been performed in a climate chamber at 20 °C and 50% relative humidity to determine the intrinsic water vapor transmission rate (WVTR) of SiNx barriers deposited at 120 °C. Intrinsic WVTR values in the range of 10(-6) g/m2/day indicate excellent barrier properties for ALD SiNx layers as thin as 10 nm, competing with that of state-of-the-art plasma-enhanced chemical vapor-deposited SiNx layers of a few hundred

  12. Plasma-Enhanced Chemical Vapor Deposition of SiOx Films Using Electron Beam Generated Plasmas

    DTIC Science & Technology

    2009-09-28

    the films was large (> 130 nm/min), which implied a high porosity for all cases except for low TEOS flow (≤ 2 sccm) at the higher (300 °C) temperature...special relation to the substrate or e-beam. A total flow of 100 sccm was used in all cases . For the gas flows mentioned above, the individual flows...beam generated plasmas. In this case , molecular hydrogen, formed primarily by recombination of atomic hydrogen on system walls, will not be

  13. Chain Assemblies from Nanoparticles Synthesized by Atmospheric Pressure Plasma Enhanced Chemical Vapor Deposition: The Computational View.

    PubMed

    Mishin, Maxim V; Zamotin, Kirill Y; Protopopova, Vera S; Alexandrov, Sergey E

    2015-12-01

    This article refers to the computational study of nanoparticle self-organization on the solid-state substrate surface with consideration of the experimental results, when nanoparticles were synthesised during atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD). The experimental study of silicon dioxide nanoparticle synthesis by AP-PECVD demonstrated that all deposit volume consists of tangled chains of nanoparticles. In certain cases, micron-sized fractals are formed from tangled chains due to deposit rearrangement. This work is focused on the study of tangled chain formation only. In order to reveal their formation mechanism, a physico-mathematical model was developed. The suggested model was based on the motion equation solution for charged and neutral nanoparticles in the potential fields with the use of the empirical interaction potentials. In addition, the computational simulation was carried out based on the suggested model. As a result, the influence of such experimental parameters as deposition duration, particle charge, gas flow velocity, and angle of gas flow was found. It was demonstrated that electrical charges carried by nanoparticles from the discharge area are not responsible for the formation of tangled chains from nanoparticles, whereas nanoparticle kinetic energy plays a crucial role in deposit morphology and density. The computational results were consistent with experimental results.

  14. Preparation and structure of porous dielectrics by plasma enhanced chemical vapor deposition

    SciTech Connect

    Gates, S. M.; Neumayer, D. A.; Sherwood, M. H.; Grill, A.; Wang, X.; Sankarapandian, M.

    2007-05-01

    The preparation of ultralow dielectric constant porous silicon, carbon, oxygen, hydrogen alloy dielectrics, called 'pSiCOH', using a production 200 mm plasma enhanced chemical vapor deposition tool and a thermal treatment is reported here. The effect of deposition temperature on the pSiCOH film is examined using Fourier transform infrared (FTIR) spectroscopy, dielectric constant (k), and film shrinkage measurements. For all deposition temperatures, carbon in the final porous film is shown to be predominantly Si-CH{sub 3} species, and lower k is shown to correlate with increased concentration of Si-CH{sub 3}. NMR and FTIR spectroscopies clearly detect the loss of a removable, unstable, hydrocarbon (CH{sub x}) phase during the thermal treatment. Also detected are increased cross-linking of the Si-O skeleton, and concentration changes for three distinct structures of carbon. In the as deposited films, deposition temperature also affects the hydrocarbon (CH{sub x}) content and the presence of C=O and C=C functional groups.

  15. Plasma-enhanced deposition and processing of transition metals and transition metal silicides for VLSI

    NASA Astrophysics Data System (ADS)

    Hess, D. W.

    1986-05-01

    Radiofrequency (rf) discharges have been used to deposit films of tungsten, molybdenum and titanium silicide. As-deposited tungsten films, from tungsten hexafluoride and hydrogen source gases, were metastable (beta W), with significant (>1 atomic percent) fluorine incorporation. Film resistivities were 40-55 micro ohm - cm due to the beta W, but dropped to about 8 micro ohm cm after a short heat treatment at 700 C which resulted in a phase transition to alpha W (bcc form). The high resistivity (>10,000 micro ohm) associated with molybdenum films deposited from molybdenum hexafluoride and hydrogen appeared to be a result of the formation of molybdenum trifluoride in the deposited material. Titanium silicide films formed from a discharge of titanium tetrachloride, silane, and hydrogen, displayed resistivities of about 150 micro ohm cm, due to small amounts of oxygen and chlorine incorporated during deposition. Plasma etching studies of tungsten films with fluorine containing gases suggest that the etchant species for tungsten in these discharges are fluorine atoms.

  16. Growth and characterization of silicon-nitride films by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Han, I. K.; Lee, Y. J.; Jo, J. W.; Lee, J. I.; Kang, K. N.

    1991-06-01

    Thin films of silicon nitride were deposited on Si wafers by plasma-enhanced chemical vapor deposition (PECVD). For deposition we designed and made hot wall capacitively coupled PECVD equipment which has a radial flow reactor. Using an RF generator of frequency 13.56 MHz and SiH 4 (5% SiH 4 in N 2) + NH 3 and N 2 as reactive gases and the carrier gas, respectively, we systematically varied the substrate temperature (240-360°C), the partial pressure of reactive gases (0.35

    deposition parameters. The characteristics of the films such as composition, deposition rate, refractive index and hydrogen content were investigated by AES, ellipsometry, FTIR spectrometry, nanospec and spectroscopic ellipsometry. As a result of these measurements, well-known characteristics were observed as a function of the substrate temperature and the partial pressure of the reactive gases. However, in our investigation of the RF power dependence of the refractive index of the film, we found that the refractive index increases and then decreases as we increase the RF power. To explain this, we considered the RF power-dependent heating effect in the glow discharge process and the amount of NH radicals which increases with the RF power.

  17. Differing morphologies of textured diamond films with electrical properties made with microwave plasma chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Lai, Wen Chi; Wu, Yu-Shiang; Chang, Hou-Cheng; Lee, Yuan-Haun

    2010-12-01

    This study investigates the orientation of textured diamond films produced through microwave plasma chemical vapor deposition (MPCVD) at 1200 W, 110 Torr, CH 4/H 2 = 1/20, with depositions times of 0.5-4.0 h. After a growth period of 2.0-4.0 h, this particular morphology revealed a rectangular structure stacked regularly on the diamond film. The orientation on {1 1 1}-textured diamond films grew a preferred orientation of {1 1 0} on the surface, as measured by XRD. The formation of the diamond epitaxial film formed textured octahedrons in ball shaped (or cauliflower-like) diamonds in the early stages (0.5 h), and the surface of the diamond film extended to pile the rectangular structure at 4.0 h. The width of the tier was approximately 200 nm at the 3.0 h point of deposition, according to TEM images. The results revealed that the textured diamond films showed two different morphological structures (typical ball shaped and rectangular diamonds), at different stages of the deposition period. The I- V characteristics of the oriented diamond films after 4.0 h of deposition time showed good conformity with the ohmic contact.

  18. Plasma deposited composite coatings to control biological response of osteoblast-like MG-63 cells

    NASA Astrophysics Data System (ADS)

    Keremidarska, M.; Radeva, E.; Eleršič, K.; Iglič, A.; Pramatarova, L.; Krasteva, N.

    2014-12-01

    The successful osseointegration of a bone implant is greatly dependent on its ability to support cellular adhesion and functions. Deposition of thin composite coatings onto the implant surface is a promising approach to improve interactions with cells without compromising implant bulk properties. In this work, we have developed composite coatings, based on hexamethyldisiloxane (HMDS) and detonation nanodiamond (DND) particles and have studied adhesion, growth and function of osteoblast-like MG-63 cells. PPHMDS/DND composites are of interest for orthopedics because they combine superior mechanical properties and good biocompatibility of DND with high adherence of HMDS to different substrata including glass, metals and plastics. We have used two approaches of the implementation of DND particles into a polymer matrix: pre-mixture of both components followed by plasma polymerization and layer-by-layer deposition of HMDS and DND particles and found that the deposition approach affects significantly the surface properties of the resulting layers and cell behaviour. The composite, prepared by subsequent deposition of monomer and DND particles was hydrophilic, with a rougher surface and MG-63 cells demonstrated better spreading, growth and function compared to the other composite which was hydrophobic with a smooth surface similarly to unmodified polymer. Thus, by varying the deposition approach, different PPHMDS/DND composite coatings, enhancing or inhibiting osteoblast adhesion and functions, can be obtained. In addition, the effect of fibronectin pre-adsorption was studied and was found to increase greatly MG-63 cell spreading.

  19. Model of a two-stage rf plasma reactor for SiC deposition

    NASA Astrophysics Data System (ADS)

    Petrov, G. M.; Giuliani, J. L.

    2001-07-01

    A reactor is proposed for plasma-enhanced chemical-vapor deposition of silicon carbide (SiC) at low pressure (˜few Torr). The inductively coupled plasma lies upstream of the growth substrate and serves to dissociate the precursor silane/propane/hydrogen inlet gas. Unlike existing reactors, the design offers the potential for separate control of the temperature in the dissociation region and at the growth substrate. The geometrical parameters and flow conditions appropriate for SiC growth are analyzed with a one-dimensional flow simulation model which includes approximations for lateral diffusive losses to cold walls as well as deposition to the substrate. Twenty-one neutral species and 24 ions are followed with 179 reactions. At 3 Torr, 10 W/cm3, and 300 cm/s inlet flow velocity, the model predicts a growth rate of ˜3 μm/h downstream from the plasma. Negligible ion density exists over the substrate as long as the silane density is sufficiently large due to a feedback process between Si+ and SiH4. Besides heating the gas, the plasma is an efficient source of radical H atoms, which in turn control the abundance of some hydrocarbon species over the substrate. C2H2 is the dominant contributor to the C-bearing flux onto the substrate and the Si atom, which forms by electron reactions, is the most important Si-bearing species. Finally, a sensitive transition in deposition rate is found for the C-bearing species as the power increases from 5 to 10 W/cm3.

  20. View factor modeling of sputter-deposition on micron-scale-architectured surfaces exposed to plasma

    SciTech Connect

    Huerta, C. E. Matlock, T. S.; Wirz, R. E.

    2016-03-21

    The sputter-deposition on surfaces exposed to plasma plays an important role in the erosion behavior and overall performance of a wide range of plasma devices. Plasma models in the low density, low energy plasma regime typically neglect micron-scale surface feature effects on the net sputter yield and erosion rate. The model discussed in this paper captures such surface architecture effects via a computationally efficient view factor model. The model compares well with experimental measurements of argon ion sputter yield from a nickel surface with a triangle wave geometry with peak heights in the hundreds of microns range. Further analysis with the model shows that increasing the surface pitch angle beyond about 45° can lead to significant decreases in the normalized net sputter yield for all simulated ion incident energies (i.e., 75, 100, 200, and 400 eV) for both smooth and roughened surfaces. At higher incident energies, smooth triangular surfaces exhibit a nonmonotonic trend in the normalized net sputter yield with surface pitch angle with a maximum yield above unity over a range of intermediate angles. The resulting increased erosion rate occurs because increased sputter yield due to the local ion incidence angle outweighs increased deposition due to the sputterant angular distribution. The model also compares well with experimentally observed radial expansion of protuberances (measuring tens of microns) in a nano-rod field exposed to an argon beam. The model captures the coalescence of sputterants at the protuberance sites and accurately illustrates the structure's expansion due to deposition from surrounding sputtering surfaces; these capabilities will be used for future studies into more complex surface architectures.

  1. Increased Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

    DOEpatents

    Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

    1997-07-08

    High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

  2. Increasing Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.

    DOEpatents

    Li, Yaun-Min; Bennett, Murray S.; Yang, Liyou

    1999-08-24

    High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

  3. Deposition of Functional Coatings Based on Intermetallic Systems TiAl on the Steel Surface by Vacuum Arc Plasma

    NASA Astrophysics Data System (ADS)

    Budilov, V.; Vardanyan, E.; Ramazanov, K.

    2015-11-01

    Laws governing the formation of intermetallic phase by sequential deposition of nano-sized layers coatings from vacuum arc plasma were studied. Mathematical modeling process of deposition by vacuum arc plasma was performed. In order to identify the structural and phase composition of coatings and to explain their physical and chemical behaviour XRD studies were carried out. Production tests of the hardened punching tools were performed.

  4. Control of carbon content in amorphous GeTe films deposited by plasma enhanced chemical vapor deposition (PE-MOCVD) for phase-change random access memory applications

    NASA Astrophysics Data System (ADS)

    Aoukar, M.; Szkutnik, P. D.; Jourde, D.; Pelissier, B.; Michallon, P.; Noé, P.; Vallée, C.

    2015-07-01

    Amorphous and smooth GeTe thin films are deposited on 200 mm silicon substrates by plasma enhanced—metal organic chemical vapor deposition (PE-MOCVD) using the commercial organometallic precursors TDMAGe and DIPTe as Ge and Te precursors, respectively. X-ray photoelectron spectroscopy (XPS) measurements show a stoichiometric composition of the deposited GeTe films but with high carbon contamination. Using information collected by Optical Emission Spectroscopy (OES) and XPS, the origin of carbon contamination is determined and the dissociation mechanisms of Ge and Te precursors in H2 + Ar plasma are proposed. As a result, carbon level is properly controlled by varying operating parameters such as plasma radio frequency power, pressure and H2 rate. Finally, GeTe films with carbon level as low as 5 at. % are obtained.

  5. Optical Emission Spectroscopy of Electron Cyclotron Resonance-Plasma Enchanced Metalorganic Chemical Vapor Deposition Process for Deposition of GaN Film

    NASA Astrophysics Data System (ADS)

    Fu, Silie; Chen, Junfang; Li, Yun; Li, Wei; Zhang, Maoping; Hu, Shejun

    2008-02-01

    An investigation was made into the nitrogen-trimethylgallium mixed electron cyclotron resonance (ECR) plasma by optical emission spectroscopy (OES). The ECR plasma enhanced metalorganic chemical vapour deposition technology was adopted to grow GaN film on an α-Al2O3 substrate. X-ray diffraction (XRD) analyses showed that the peak of GaN (0002) was at 2θ = 34.48°, being sharper and more intense with the increase in the N2: trimethylgallium(TMG) flow ratio. The results demonstrate that the electron cyclotron resonance-plasma enchanced metalorganic chemical vapor deposition (ECR-MOPECVD) technology is evidently advantageous for the deposition of GaN film at a low growth temperature.

  6. Plasma diagnostic approach for the low-temperature deposition of silicon quantum dots using dual frequency PECVD

    NASA Astrophysics Data System (ADS)

    Sahu, B. B.; Yin, Y.; Lee, J. S.; Han, Jeon G.; Shiratani, M.

    2016-10-01

    Although studies of silicon (Si) quantum dots (QDs) were started just a few years ago, progress is noteworthy concerning unique film properties and their potential application for devices. In particular, relating to the Si QD process optimization, it is essential to control the deposition environment by studying the role of plasma parameters and atomic and molecular species in the process plasmas. In this work, we report on advanced material processes for the low-temperature deposition of Si QDs by utilizing radio frequency and ultrahigh frequency dual frequency (DF) plasma enhanced chemical vapor deposition (PECVD) method. DF PECVD can generate a very high plasma density in the range ~9  ×  1010 cm-3 to 3.2  ×  1011 cm-3 at a very low electron temperature (T e) ~ 1.5 to 2.4 eV. The PECVD processes, using a reactive mixture of H2/SiH4/NH3 gases, are carefully studied to investigate the operating regime and to optimize the deposition parameters by utilizing different plasma diagnostic tools. The analysis reveals that a higher ion flux at a higher plasma density on the substrate is conducive to enhancing the overall crystallinity of the deposited film. Along with high-density plasmas, a high concentration of atomic H and N is simultaneously essential for the high growth rate deposition of Si QDs. Numerous plasma diagnostics methods and film analysis tools are used to correlate the effect of plasma- and atomic-radical parameters on the structural and chemical properties of the deposited Si QD films prepared in the reactive mixtures of H2/SiH4/NH3 at various pressures.

  7. Surface reaction mechanisms during ozone and oxygen plasma assisted atomic layer deposition of aluminum oxide.

    PubMed

    Rai, Vikrant R; Vandalon, Vincent; Agarwal, Sumit

    2010-09-07

    We have elucidated the reaction mechanism and the role of the reactive intermediates in the atomic layer deposition (ALD) of aluminum oxide from trimethyl aluminum in conjunction with O(3) and an O(2) plasma. In situ attenuated total reflection Fourier transform infrared spectroscopy data show that both -OH groups and carbonates are formed on the surface during the oxidation cycle. These carbonates, once formed on the surface, are stable to prolonged O(3) exposure in the same cycle. However, in the case of plasma-assisted ALD, the carbonates decompose upon prolonged O(2) plasma exposure via a series reaction kinetics of the type, A (CH(3)) --> B (carbonates) --> C (Al(2)O(3)). The ratio of -OH groups to carbonates on the surface strongly depends on the oxidizing agent, and also the duration of the oxidation cycle in plasma-assisted ALD. However, in both O(3) and O(2) plasma cycles, carbonates are a small fraction of the total number of reactive sites compared to the hydroxyl groups.

  8. Egg-shell deposition and blood plasma inorganic phosphorus concentration in individual laying hens.

    PubMed

    Gunaratne, S P; Boorman, K N

    1996-03-01

    1. The relationship between plasma inorganic phosphorus measured at the end of the dark period and the weight of the next egg shell produced was investigated in 30 Hisex Brown hens. 2. Hens received an adequate conventional layers' diet and the lighting pattern was conventional (17 L: 7 D). Observations were made early (31 to 40 weeks) and late (62 to 68 weeks of age) in the laying period. 3. Eggs were classified by position in the clutch sequence and significant negative correlations were found between shell weights of early eggs in the sequence and plasma phosphate at the end of the dark period. 4. No significant trends were found in plasma total calcium. 5. No significant differences were found in bone compositions of birds producing consistently more or less than average shell weight during the laying period. 6. The negative correlations between plasma phosphate and shell weight are consistent with the observations of Sauveur and Mongin (1983) and show that impairment of shell deposition is associated with skeletal mobilisation as indicated by increase in plasma phosphate. This is consistent with the observations on bone composition and indicates that selection for shell quality will tend to select birds which are not dependent on excessive skeletal mobilisation during shell formation.

  9. PREFACE: VI Scientific Technical Conference on "Low-temperature plasma during the deposition of functional coatings"

    NASA Astrophysics Data System (ADS)

    2014-11-01

    The VI Republican Scientific Technical Conference "Low-temperature plasma during the deposition of functional coatings" took place from 4 to 7 November 2014 at the Academy of Sciences of the Republic of Tatarstan and the Kazan Federal University. The conference was chaired by a Member of the Academy of Sciences of the Republic of Tatarstan Nail Kashapov -Professor, Doctor of Technical Sciences- a member of the Scientific and Technical Council of the Ministry of Economy of the Republic of Tatarstan. At the conference, the participants discussed a wide range of issues affecting the theoretical and computational aspects of research problems in the physics and technology of low-temperature plasma. A series of works were devoted to the study of thin films obtained by low-temperature plasma. This year work dedicated to the related field of heat mass transfer in multiphase media and low-temperature plasma was also presented. Of special interest were reports on the exploration of gas discharges with liquid electrolytic electrotrodes and the study of dusty plasmas. Kashapov Nail, D.Sc., Professor (Kazan Federal University)

  10. Long period gratings coated with hafnium oxide by plasma-enhanced atomic layer deposition for refractive index measurements.

    PubMed

    Melo, Luis; Burton, Geoff; Kubik, Philip; Wild, Peter

    2016-04-04

    Long period gratings (LPGs) are coated with hafnium oxide using plasma-enhanced atomic layer deposition (PEALD) to increase the sensitivity of these devices to the refractive index of the surrounding medium. PEALD allows deposition at low temperatures which reduces thermal degradation of UV-written LPGs. Depositions targeting three different coating thicknesses are investigated: 30 nm, 50 nm and 70 nm. Coating thickness measurements taken by scanning electron microscopy of the optical fibers confirm deposition of uniform coatings. The performance of the coated LPGs shows that deposition of hafnium oxide on LPGs induces two-step transition behavior of the cladding modes.

  11. All-oxide broadband antireflection coatings by plasma ion assisted deposition: design, simulation, manufacturing and re-optimization.

    PubMed

    Wilbrandt, Steffen; Stenzel, Olaf; Kaiser, Norbert

    2010-09-13

    A new all-oxide design for broadband antireflection coatings with significantly reduced impact of deposition errors to the final reflectance is presented. Computational manufacturing including re-optimization during deposition has been used in the design work to account for maximum insensibility of the design with respect to deposition errors typical for plasma ion assisted deposition PIAD. Repeated deposition runs with the deducted monitoring and re-optimization strategy verify the validity of the simulations and the stability of the derived design solution.

  12. Erosion and re-deposition of lithium and boron coatings under high-flux plasma bombardment

    NASA Astrophysics Data System (ADS)

    Abrams, Tyler Wayne

    Lithium and boron coatings are applied to the walls of many tokamaks to enhance performance and protect the underlying substrates. Li and B-coated high-Z substrates are planned for use in NSTX-U and are a candidate plasma-facing component (PFC) for DEMO. However, previous measurements of Li evaporation and thermal sputtering on low-flux devices indicate that the Li temperature permitted on such devices may be unacceptably low. Thus it is crucial to characterize gross and net Li erosion rates under high-flux plasma bombardment. Additionally, no quantitative measurements have been performed of the erosion rate of a boron-coated PFC during plasma bombardment. A realistic model for the compositional evolution of a Li layer under D bombardment was developed that incorporates adsorption, implantation, and diffusion. A model was developed for temperature-dependent mixed-material Li-D erosion that includes evaporation, physical sputtering, chemical sputtering, preferential sputtering, and thermal sputtering. The re-deposition fraction of a Li coating intersecting a linear plasma column was predicted using atomic physics information and by solving the Li continuity equation. These models were tested in the Magnum-PSI linear plasma device at ion fluxes of 1023-1024 m-2 s-1 and Li surface temperatures less than 800 degrees C. Li erosion was measured during bombardment with a neon plasma that will not chemically react with Li and the results agreed well with the erosion model. Next the ratio of the total D fluence to the areal density of the Li coating was varied to quantify differences in Li erosion under D plasma bombardment as a function of the D concentration. The ratio of D/Li atoms was calculated using the results of MD simulations and good agreement is observed between measurements and the predictions of the mixed-material erosion model. Li coatings are observed to disappear from graphite much faster than from TZM Mo, indicating that fast Li diffusion into the bulk

  13. Erosion and re-deposition of lithium and boron coatings under high-flux plasma bombardment

    SciTech Connect

    Abrams, Tyler Wayne

    2015-01-01

    Lithium and boron coatings are applied to the walls of many tokamaks to enhance performance and protect the underlying substrates. Li and B-coated high-Z substrates are planned for use in NSTX-U and are a candidate plasma-facing component (PFC) for DEMO. However, previous measurements of Li evaporation and thermal sputtering on low-flux devices indicate that the Li temperature permitted on such devices may be unacceptably low. Thus it is crucial to characterize gross and net Li erosion rates under high-flux plasma bombardment. Additionally, no quantitative measurements have been performed of the erosion rate of a boron-coated PFC during plasma bombardment. A realistic model for the compositional evolution of a Li layer under D bombardment was developed that incorporates adsorption, implantation, and diffusion. A model was developed for temperature-dependent mixed-material Li-D erosion that includes evaporation, physical sputtering, chemical sputtering, preferential sputtering, and thermal sputtering. The re-deposition fraction of a Li coating intersecting a linear plasma column was predicted using atomic physics information and by solving the Li continuity equation. These models were tested in the Magnum-PSI linear plasma device at ion fluxes of 10^23-10^24 m^-2 s^-1 and Li surface temperatures less than 800 degrees C. Li erosion was measured during bombardment with a neon plasma that will not chemically react with Li and the results agreed well with the erosion model. Next the ratio of the total D fluence to the areal density of the Li coating was varied to quantify differences in Li erosion under D plasma bombardment as a function of the D concentration. The ratio of D/Li atoms was calculated using the results of MD simulations and good agreement is observed between measurements and the predictions of the mixed-material erosion model. Li coatings are observed to disappear from graphite much faster than from TZM Mo, indicating that fast Li diffusion into the bulk

  14. Preparation and characterization of ZnO-deposited DBD plasma-treated PP packaging film with antibacterial activities

    NASA Astrophysics Data System (ADS)

    Paisoonsin, Sutida; Pornsunthorntawee, Orathai; Rujiravanit, Ratana

    2013-05-01

    Zinc oxide (ZnO)-deposited polypropylene (PP) packaging film was prepared with the aid of dielectric barrier discharge (DBD) plasma treatment. The surface hydrophilicity of PP film was found to increase after the DBD plasma treatment due to the presence of oxygen-containing functional groups on the DBD plasma-treated PP surface. Although the surface roughness of the DBD plasma-treated PP film gradually increased with increasing plasma treatment time, the DBD plasma treatment insignificantly affected the mechanical properties of the PP film. The DBD plasma treatment time was found to be optimized at 10 s. The DBD plasma-treated PP film was further immersed in an aqueous zinc nitrate (Zn(NO3)2) solution at different concentrations before being converted to ZnO particles with the use of a 2.5 M sodium hydroxide (NaOH) solution, followed by sonication. The highest amount of ZnO deposited on the DBD plasma-treated PP surface was about 0.26 wt.% at the optimum Zn(NO3)2 concentration of 0.5 M. The ZnO-deposited DBD plasma-treated PP film showed good antibacterial activities against gram-positive Staphylococcus auerus and gram-negative Escherichia coli.

  15. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    SciTech Connect

    Hemawan, Kadek W.; Gou, Huiyang; Hemley, Russell J.

    2015-11-02

    Polycrystalline diamond has been synthesized on silicon substrates at atmospheric pressure, using a microwave capillary plasma chemical vapor deposition technique. The CH{sub 4}/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H{sub 2} into the deposition gas chemistry. Electronically excited species of CN, C{sub 2}, Ar, N{sub 2}, CH, H{sub β}, and H{sub α} were observed in the emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T{sub 2g} phonon at 1333 cm{sup −1} peak relative to the Raman features of graphitic carbon. Field emission scanning electron microscopy images reveal that, depending on the growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

  16. Diamond synthesis at atmospheric pressure by microwave capillary plasma chemical vapor deposition

    SciTech Connect

    Gou, Huiyang; Hemley, Russell J.; Hemawan, Kadek W.

    2015-11-02

    Polycrystalline diamond has been successfully synthesized on silicon substrates at atmospheric pressure using a microwave capillary plasma chemical vapor deposition technique. The CH4/Ar plasma was generated inside of quartz capillary tubes using 2.45 GHz microwave excitation without adding H2 into the deposition gas chemistry. Electronically excited species of CN, C2, Ar, N2, CH, Hβ and Hα were observed in emission spectra. Raman measurements of deposited material indicate the formation of well-crystallized diamond, as evidenced by the sharp T2g phonon at 1333 cm-1 peak relative to the Raman features of graphitic carbon. Furthermore, field emission scanning electron microscopy (SEM) images reveal that, depending on the on growth conditions, the carbon microstructures of grown films exhibit “coral” and “cauliflower-like” morphologies or well-facetted diamond crystals with grain sizes ranging from 100 nm to 10 μm.

  17. Preparation of a platinum electrocatalyst by coaxial pulse arc plasma deposition

    PubMed Central

    Agawa, Yoshiaki; Tanaka, Hiroyuki; Torisu, Shigemitsu; Endo, Satoshi; Tsujimoto, Akihiro; Gonohe, Narishi; Malgras, Victor; Aldalbahi, Ali; Alshehri, Saad M; Kamachi, Yuichiro; Li, Cuiling; Yamauchi, Yusuke

    2015-01-01

    We have developed a new method of preparing Pt electrocatalysts through a dry process. By coaxial pulse arc plasma deposition (CAPD), highly ionized metal plasma can be generated from a target rod without any discharged gases, and Pt nanoparticles can be deposited on a carbon support. The small-sized Pt nanoparticles are distributed over the entire carbon surface. From transmission electron microscopy (TEM), the average size of the deposited Pt nanoparticles is estimated to be 2.5 nm, and their size distribution is narrow. Our electrocatalyst shows considerably improved catalytic activity and stability toward methanol oxidation reaction (MOR) compared with commercially available Pt catalysts such as Pt black and Pt/carbon (PtC). Inspired by its very high efficiency toward MOR, we also measured the catalytic performance for oxygen reduction reaction (ORR). Our PtC catalyst shows a better performance with half-wave potential of 0.87 V, which is higher than those of commercially available Pt catalysts. The higher performance is also supported by a right-shifted onset potential. Our preparation is simple and could be applied to other metallic nanocrystals as a novel platform in catalysis, fuel cells and biosensors. PMID:27877765

  18. Friction and wear of plasma-deposited amorphous hydrogenated films on silicon nitride

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1991-01-01

    An investigation was conducted to examine the friction and wear behavior of amorphous hydrogenated carbon (a-C:H) films in sliding contact with silicon nitride pins in both dry nitrogen and humid air environments. Amorphous hydrogenated carbon films approximately 0.06 micron thick were deposited on silicon nitride flat substrates by using the 30 kHz ac glow discharge of a planar plasma reactor. The results indicate that an increase in plasma deposition power gives an increase in film density and hardness. The high-density a-C:H films deposited behaved tribologically much like bulk diamond. In the dry nitrogen environment, a tribochemical reaction produced a substance, probably a hydrocarbon-rich layer, that decreased the coefficient of friction. In the humid air environment, tribochemical interactions drastically reduced the wear life of a-C:H films and water vapor greatly increased the friction. Even in humid air, effective lubrication is possible with vacuum-annealed a-C:H films. The vacuum-annealed high-density a-C:H film formed an outermost superficial graphitic layer, which behaved like graphite, on the bulk a-C:H film. Like graphite, the annealed a-C:H film with the superficial graphitic layer showed low friction when adsorbed water vapor was present.

  19. Facile plasma-enhanced deposition of ultrathin crosslinked amino acid films for conformal biometallization.

    PubMed

    Anderson, Kyle D; Slocik, Joseph M; McConney, Michael E; Enlow, Jesse O; Jakubiak, Rachel; Bunning, Timothy J; Naik, Rajesh R; Tsukruk, Vladimir V

    2009-03-01

    A novel method for the facile fabrication of conformal, ultrathin, and uniform synthetic amino acid coatings on a variety of practical surfaces by plasma-enhanced chemical vapor deposition is introduced. Tyrosine, which is utilized as an agent to reduce gold nanoparticles from solution, is sublimed into the plasma field and directly deposited on a variety of substrates to form a homogeneous, conformal, and robust polyamino acid coating in a one-step, solvent-free process. This approach is applicable to many practical surfaces and allows surface-induced biometallization while avoiding multiple wet-chemistry treatments that can damage many soft materials. Moreover, by placing a mask over the substrate during deposition, the tyrosine coating can be micropatterned. Upon its exposure to a solution of gold chloride, a network of gold nanoparticles forms on the surface, replicating the initial micropattern. This method of templated biometallization is adaptable to a variety of practical inorganic and organic substrates, such as silicon, glass, nitrocellulose, polystyrene, polydimethylsiloxane, polytetrafluoroethylene, polyethylene, and woven silk fibers. No special pretreatment is necessary, and the technique results in a rapid, conformal amino acid coating that can be utilized for further biometallization.

  20. Plasma-enhanced atomic layer deposition for plasmonic TiN

    NASA Astrophysics Data System (ADS)

    Otto, Lauren M.; Hammack, Aaron T.; Aloni, Shaul; Ogletree, D. Frank; Olynick, Deirdre L.; Dhuey, Scott; Stadler, Bethanie J. H.; Schwartzberg, Adam M.

    2016-09-01

    This work presents the low temperature plasma-enhanced atomic layer deposition (PE-ALD) of TiN, a promising plasmonic synthetic metal. The plasmonics community has immediate needs for alternatives to traditional plasmonic materials (e.g. Ag and Au), which lack chemical, thermal, and mechanical stability. Plasmonic alloys and synthetic metals have significantly improved stability, but their growth can require high-temperatures (>400 °C), and it is difficult to control the thickness and directionality of the resulting film, especially on technologically important substrates. Such issues prevent the application of alternative plasmonic materials for both fundamental studies and large-scale industrial applications. Alternatively, PE-ALD allows for conformal deposition on a variety of substrates with consistent material properties. This conformal coating will allow the creation of exotic three-dimensional structures, and low-temperature deposition techniques will provide unrestricted usage across a variety of platforms. The characterization of this new plasmonic material was performed with in-situ spectroscopic ellipsometry as well as Auger electron spectroscopy for analysis of TiN film sensitivity to oxide cross-contamination. Plasmonic TiN films were fabricated, and a chlorine plasma etch was found to pattern two dimensional gratings as a test structure. Optical measurements of 900 nm period gratings showed reasonable agreement with theoretical modeling of the fabricated structures, indicating that ellipsometry models of the TiN were indeed accurate.

  1. Adhesion, friction, and wear of plasma-deposited thin silicon nitride films at temperatures to 700 C

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Pouch, J. J.; Alterovitz, S. A.; Pantic, D. M.; Johnson, G. A.

    1988-01-01

    The adhesion, friction, and wear behavior of silicon nitride films deposited by low- and high-frequency plasmas (30 kHz and 13.56 MHz) at various temperatures to 700 C in vacuum were examined. The results of the investigation indicated that the Si/N ratios were much greater for the films deposited at 13.56 MHz than for those deposited at 30 kHz. Amorphous silicon was present in both low- and high-frequency plasma-deposited silicon nitride films. However, more amorphous silicon occurred in the films deposited at 13.56 MHz than in those deposited at 30 kHz. Temperature significantly influenced adhesion, friction, and wear of the silicon nitride films. Wear occurred in the contact area at high temperature. The wear correlated with the increase in adhesion and friction for the low- and high-frequency plasma-deposited films above 600 and 500 C, respectively. The low- and high-frequency plasma-deposited thin silicon nitride films exhibited a capability for lubrication (low adhesion and friction) in vacuum at temperatures to 500 and 400 C, respectively.

  2. Surface hardening of VT-22 alloy by inductively coupled plasma nitriding and magnetron deposition of TiN films

    NASA Astrophysics Data System (ADS)

    Kharkov, Maxim M.; Kaziev, Andrey V.; Tumarkin, Alexander V.; Drobinin, Vyacheslav E.; Stepanova, Tatiana V.; Pisarev, Alexander A.

    2017-01-01

    The surface of VT-22 Russian grade titanium alloy samples was modified by inductively coupled plasma (ICP) nitriding followed by magnetron deposition of TiN coatings. Different operating conditions of ICP nitriding and magnetron deposition were considered. The microhardness depth profiles were measured for samples after nitriding. The performance of TiN coatings was examined with a scratch tester.

  3. Time-resolved diagnostics of excimer laser-generated ablation plasmas used for pulsed laser deposition

    SciTech Connect

    Geohegan, D.B.

    1994-09-01

    Characteristics of laser plasmas used for pulsed laser deposition (PLD) of thin films are examined with four in situ diagnostic techniques: Optical emission spectroscopy, optical absorption spectroscopy, ion probe studies, and gated ICCD (intensified charge-coupled-device array) fast photography. These four techniques are complementary and permit simultaneous views of the transport of ions, excited states, ground state neutrals and ions, and hot particulates following KrF laser ablation of YBCO, BN, graphite and Si in vacuum and background gases. The implementation and advantages of the four techniques are first described in order to introduce the key features of laser plasmas for pulsed laser deposition. Aspects of the interaction of the ablation plume with background gases (i.e., thermalization, attenuation, shock formation) and the collision of the plasma plume with the substrate heater are then summarized. The techniques of fast ICCD photography and gated photon counting are then applied to investigate the temperature, velocity, and spatial distribution of hot particles generated during KrF ablation of YBCO, BN, Si and graphite. Finally, key features of fast imaging of the laser ablation of graphite into high pressure rare gases are presented in order to elucidate internal reflected shocks within the plume, redeposition of material on a surface, and formation of hot nanoparticles within the plume.

  4. Formation of microchannels from low-temperature plasma-deposited silicon oxynitride

    DOEpatents

    Matzke, Carolyn M.; Ashby, Carol I. H.; Bridges, Monica M.; Manginell, Ronald P.

    2000-01-01

    A process for forming one or more fluid microchannels on a substrate is disclosed that is compatible with the formation of integrated circuitry on the substrate. The microchannels can be formed below an upper surface of the substrate, above the upper surface, or both. The microchannels are formed by depositing a covering layer of silicon oxynitride over a mold formed of a sacrificial material such as photoresist which can later be removed. The silicon oxynitride is deposited at a low temperature (.ltoreq.100.degree. C.) and preferably near room temperature using a high-density plasma (e.g. an electron-cyclotron resonance plasma or an inductively-coupled plasma). In some embodiments of the present invention, the microchannels can be completely lined with silicon oxynitride to present a uniform material composition to a fluid therein. The present invention has applications for forming microchannels for use in chromatography and electrophoresis. Additionally, the microchannels can be used for electrokinetic pumping, or for localized or global substrate cooling.

  5. Effect of buoyancy on power deposition in microwave cavity hydrogen plasma source

    NASA Astrophysics Data System (ADS)

    Prasanna, S.; Rond, C.; Michau, A.; Hassouni, K.; Gicquel, A.

    2016-08-01

    A self-consistent model describing the coupling of resonant microwave radiation and plasma has been constructed. This model improves upon the models developed by Hassouni et al and Hagelaar et al, in 1999 and 2004, respectively with inclusion of hydrodynamic effects. The model has been used to study the effect of buoyancy on power deposition in microwave assisted hydrogen plasmas at different operating pressures over the range 25-300 mbar and power over the range 400 and 4000 W. Three cases viz. normal reactor (g  =  -9.81 m s-2, negative buoyancy), pure diffusion (g  =  0 m s-2) and the inverted case (g  =  9.81 m s-2, positive buoyancy) were considered. Buoyancy effects in the cavity become important at high power / pressure operating conditions. The formation of a secondary plasma zone is strongly increased in the presence of negative buoyancy, while positive buoyancy and diffusion cases are more stable. Also the density of atomic hydrogen close to the substrate is larger with a wider radial spread for the positive buoyancy case over normal operating conditions which augurs well for achieving good deposition of diamond.

  6. Fluoropolymer Films Deposited by RF Plasma Sputtering of Polytetrafluoroethylene Using Inert Gases

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Wydeven, Theodore; Kliss, Mark (Technical Monitor)

    1998-01-01

    The FT-IR (Fourier Transform Infrared), UV (Ultraviolet) and XPS (X Ray Photoelectron Spectroscopy) spectra of fluoropolymer films (SPTFE) deposited by rf (radio frequency) plasma sputtering of polytetrafluoroethylene (PTFE), using Ne, Kr and Xe as sputtering gases, were obtained and compared with prior spectra for SPTFE formed using He and Ar. The F/C (fluorine / carbon) ratios for SPTFE films (1.44-1.55), obtained at a rf power of 10 W, were essentially the same for all five rare gases, there being no trend of decreasing fluorine content in the SPTFE product with increasing atomic weight of the sputtering gas - contrary to the momentum transfer notion advanced by M. E. Ryan, et al. Increasing rf power from 10 to 50 W resulted in successively lower F/C ratios for SPTFE (e.g., from 1.55 to 1.21 in the case of Xe plasma-sputtered PTFE), accompanied by sputtering of the glass reactor and deposition of fragments of sodium aluminum silicate occurring at 40 W and above. In order to achieve a "Teflon-like" SPTFE structure (i.e., products with as high a F/C ratio as possible) in a given plasma reactor, an optimum rf power must be found, which in the present case was approximately 10 W.

  7. Influences on ionization fraction in an inductively coupled ionized physical vapor deposition device plasma

    NASA Astrophysics Data System (ADS)

    Juliano, Daniel R.; Ruzic, David N.; Allain, Monica M. C.; Hayden, Douglas B.

    2002-01-01

    A computer simulation was created to model the transport of sputtered atoms through an ionized physical vapor deposition (IPVD) system. The simulation combines Monte Carlo and fluid methods to track the metal atoms that are emitted from the target, interact with the IPVD plasma, and are eventually deposited somewhere in the system. Ground-state neutral, excited, and ionized metal atoms are tracked. The simulation requires plasma conditions to be specified by the user. Langmuir probe measurements were used to determine these parameters in an experimental system in order to compare simulation results with experiment. The primary product of the simulation is a prediction of the ionization fraction of the sputtered atom flux at the substrate under various conditions. This quantity was experimentally measured and the results compared to the simulation. Experiment and simulation differ significantly. It is hypothesized that heating of the background gas due to the intense sputtered atom flux at the target is primarily responsible for this difference. Heating of the background gas is not accounted for in the simulation. Difficulties in accurately measuring plasma parameters, especially electron temperature, are also significant.

  8. Surface-Wave Plasma Deposition of a-C:H Films for Field Emission

    NASA Astrophysics Data System (ADS)

    Sano, Toru; Nagatsu, Masaaki; Takada, Noriharu; Toyoda, Hirotaka; Sugai, Hideo; Guang, W. X.; Hirao, Takashi; Toyoda, Naoki

    2000-10-01

    Recently crystalline diamond or diamondlike carbon (DLC) thin films prepared by the plasma enhanced CVD techniques have been widely studied as a new material of electron emitter for the next generation large-area field emission display. Among them, DLC films grown at low temperature are more attractive from an aspect of industrial manufacturing. In this study, we have carried out the deposition of hydrogenated amorphous carbon(a-C:H) films using a high density, low pressure surface-wave plasma (SWP). The SWP was produced in a 40cm-diameter vacuum chamber by introducing 2.45 GHz microwave through a quartz window via slot antennas. The a-C:H films were deposited on a silicon substrate immersed in He/CH4 plasma, under discharge conditions of 700 W microwave power and 200 mTorr total pressure. Excellent field emission characteristics were obtained: the threshold electric field defined at an emission current density of 1 μA/cm^2 was obtained to be 4 V/μm. Other film characteristics measured with the XPS and FT-IR are also presented. This work was supported by a Grant-in-Aid for Science Research from the Ministry of Education, Science, Sports and Culture in Japan.

  9. Fluoropolymer Films Deposited by RF Plasma Sputtering of Polytetrafluoroethylene Using Inert Gases

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Wydeven, Theodore; Kliss, Mark (Technical Monitor)

    1998-01-01

    The FT-IR (Fourier Transform Infrared), UV (Ultraviolet) and XPS (X Ray Photoelectron Spectroscopy) spectra of fluoropolymer films (SPTFE) deposited by rf (radio frequency) plasma sputtering of polytetrafluoroethylene (PTFE), using Ne, Kr and Xe as sputtering gases, were obtained and compared with prior spectra for SPTFE formed using He and Ar. The F/C (fluorine / carbon) ratios for SPTFE films (1.44-1.55), obtained at a rf power of 10 W, were essentially the same for all five rare gases, there being no trend of decreasing fluorine content in the SPTFE product with increasing atomic weight of the sputtering gas - contrary to the momentum transfer notion advanced by M. E. Ryan, et al. Increasing rf power from 10 to 50 W resulted in successively lower F/C ratios for SPTFE (e.g., from 1.55 to 1.21 in the case of Xe plasma-sputtered PTFE), accompanied by sputtering of the glass reactor and deposition of fragments of sodium aluminum silicate occurring at 40 W and above. In order to achieve a "Teflon-like" SPTFE structure (i.e., products with as high a F/C ratio as possible) in a given plasma reactor, an optimum rf power must be found, which in the present case was approximately 10 W.

  10. Plasma enhanced atomic layer deposition of ZnO with diethyl zinc and oxygen plasma: Effect of precursor decomposition

    SciTech Connect

    Muneshwar, Triratna Cadien, Ken; Shoute, Gem; Barlage, Doug

    2016-09-15

    Although atomic layer deposition (ALD) of ZnO using diethyl zinc (DEZ) precursor has been extensively reported, variation in growth-per-cycle (GPC) values and the range of substrate temperature (T{sub sub}) for ALD growth between related studies remain unexplained. For identical processes, GPC for the characteristic self-limiting ALD growth is expected to be comparable. Hence, a significant variation in GPC among published ZnO ALD studies strongly suggests a concealed non-ALD growth component. To investigate this, the authors report plasma-enhanced ALD growth of ZnO using DEZ precursor and O{sub 2} inductively coupled plasma. The effect of T{sub sub} on ZnO GPC was studied with deposition cycles (1) 0.02 s–15 s–6 s–15 s, (2) 0.10 s–15 s–15 s–15 s, and (3) 0.20 s–15 s–30 s–15 s, where the cycle parameters t{sub 1}–t{sub 2}–t{sub 3}–t{sub 4} denote duration of DEZ pulse, post-DEZ purge, plasma exposure, and postplasma purge, respectively. The non-ALD growth characteristics observed at T{sub sub} ≥ 60 °C are discussed and attributed to DEZ precursor decomposition. The authors demonstrate ZnO growth at T{sub sub} = 50 °C to be self-limiting with respect to both t{sub 1} and t{sub 3} giving GPC of 0.101 ± 0.001 nm/cycle. The effect of precursor decomposition related (non-ALD) growth at T{sub sub} ≥ 60 °C is illustrated from comparison of optical dielectric function, electrical resistivity, and surface roughness of ZnO films deposited at T{sub sub} = 50, 125, and 200 °C.

  11. Plasma deposited diamondlike carbon on GaAs and InP

    NASA Technical Reports Server (NTRS)

    Warner, J. D.; Pouch, J. J.; Alterovitz, S. A.; Liu, D. C.; Lanford, W. A.

    1984-01-01

    The properties of diamond like carbon films grown by RF flow discharge 30 kHz plasma using methane are reported. The Cls XPS line shape of films showed localized hybrid carbon bonds as low as 40 to as high as 95 percent. Infrared spectroscopy and N(15) nuclear reaction profiling data indicated 35 to 42 percent hydrogen, depending inversely on deposition temperature. The deposition rate of films on Si falls off exponentially with substrate temperature, and nucleation does not occur above 200 C on GaAs and InP. Optical data of the films showed bandgap values of 2.0 to 2.4 eV increasing monotonically with CH4 flow rate.

  12. Plasma deposited hydrogenated carbon on GaAs and InP

    NASA Technical Reports Server (NTRS)

    Warner, J. D.; Pouch, J. J.; Alterovitz, S. A.; Liu, D. C.; Lanford, W. A.

    1985-01-01

    The properties of diamond like carbon films grown by RF flow discharge 30 kHz plasma using methane are reported. The Cis XPS line shape of films showed localized hybrid carbon bonds as low as 40 to as high as 95 percent. Infrared spectroscopy and N(15) nuclear reaction profiling data indicated 35 to 42 percent hydrogen, depending inversely on deposition temperature. The deposition rate of films on Si falls off exponentially with substrate temperature, and nucleation does not occur above 200 C on GaAs and InP. Optical data of the films showed bandgap values of 2.0 to 2.4 eV increasing monotonically with CH4 flow rate.

  13. Critical issues in plasma deposition of microcrystalline silicon for thin film transistors

    NASA Astrophysics Data System (ADS)

    Roca i Cabarrocas, Pere; Djeridane, Yassine; Bui, V. D.; Bonnassieux, Yvan; Abramov, Alexey

    2008-03-01

    After more than 20 years of research and despite improved transport properties with respect to amorphous silicon, microcrystalline silicon thin film transistors (TFTs) are not yet ready for industrial production. We review here the progress made in the understanding of the growth of this material with particular emphasis on industry relevant aspects such as deposition rate and uniformity. We show that the synthesis of silicon nanocrystals in the plasma offers unique advantages with respect to deposition rate and film properties. In particular, this allows the production of films which are similar to polycrystalline thin films produced by furnace and laser crystallization. The growth process is also discussed with respect to TFT design: top gate or bottom gate. Results on bottom gate TFTs meeting all the necessary requirements in terms of mobility, ON/OFF ratio and stability required for AMOLED applications are also reported.

  14. Influence of plasma spraying deposition process on optical properties of hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Belka, Radosław; Kowalski, Szymon; Żórawski, Wojciech; Suchańska, Małgorzata

    2015-09-01

    Hydroxyapatite (HAp) is a well-known bioceramic, nonorganic material of the bones of the vertebrate responsible for their mechanical durability. In human bones it occupies 60-80 % of the volume depending on a number of factors. Synthetic HAp is valued in bone endoprosthetic to its high biocompatibility. It is widely used to fill cavities of bone and as the coating of bone implants to increase their biocompatibility and adhesion to bone surface. In this paper a diffuse reflectance spectra of plasma-spraying deposited hydroxyapatite were presented and compared with pure powder samples. Optical band gap were estimated basing on Kubelka-Munk functions and Tauc plot extrapolation. We found that deposition process affects the value of band gap.

  15. Plasma deposited hydrogenated carbon on GaAs and InP

    NASA Technical Reports Server (NTRS)

    Warner, J. D.; Pouch, J. J.; Alterovitz, S. A.; Liu, D. C.; Lanford, W. A.

    1985-01-01

    The properties of diamond like carbon films grown by RF flow discharge 30 kHz plasma using methane are reported. The Cis XPS line shape of films showed localized hybrid carbon bonds as low as 40 to as high as 95 percent. Infrared spectroscopy and N(15) nuclear reaction profiling data indicated 35 to 42 percent hydrogen, depending inversely on deposition temperature. The deposition rate of films on Si falls off exponentially with substrate temperature, and nucleation does not occur above 200 C on GaAs and InP. Optical data of the films showed bandgap values of 2.0 to 2.4 eV increasing monotonically with CH4 flow rate.

  16. Low-Energy Plasma Spray (LEPS) Deposition of Hydroxyapatite/Poly-ɛ-Caprolactone Biocomposite Coatings

    NASA Astrophysics Data System (ADS)

    Garcia-Alonso, Diana; Parco, Maria; Stokes, Joseph; Looney, Lisa

    2012-01-01

    Thermal spraying is widely employed to deposit hydroxyapatite (HA) and HA-based biocomposites on hip and dental implants. For thick HA coatings (>150 μm), problems are generally associated with the build-up of residual stresses and lack of control of coating crystallinity. HA/polymer composite coatings are especially interesting to improve the pure HA coatings' mechanical properties. For instance, the polymer may help in releasing the residual stresses in the thick HA coatings. In addition, the selection of a bioresorbable polymer may enhance the coatings' biological behavior. However, there are major challenges associated with spraying ceramic and polymeric materials together because of their very different thermal properties. In this study, pure HA and HA/poly-ɛ-caprolactone (PCL) thick coatings were deposited without significant thermal degradation by low-energy plasma spraying (LEPS). PCL has never been processed by thermal spraying, and its processing is a major achievement of this study. The influence of selected process parameters on microstructure, composition, and mechanical properties of HA and HA/PCL coatings was studied using statistical design of experiments (DOE). The HA deposition rate was significantly increased by the addition of PCL. The average porosity of biocomposite coatings was slightly increased, while retaining or even improving in some cases their fracture toughness and microhardness. Surface roughness of biocomposites was enhanced compared with HA pure coatings. Cell culture experiments showed that murine osteoblast-like cells attach and proliferate well on HA/PCL biocomposite deposits.

  17. Structural and optical properties of silicon nanocrystals grown by plasma-enhanced chemical vapor deposition.

    PubMed

    Prakash, G V; Daldosso, N; Degoli, E; Iacona, F; Cazzanelli, M; Gaburro, Z; Pucker, G; Dalba, P; Rocca, F; Ceretta Moreira, E; Franzò, G; Pacifici, D; Priolo, F; Arcangeli, C; Filonov, A B; Ossicini, S; Pavesi, L

    2001-06-01

    Silicon nanocrystals (Si-nc) embedded in SiO2 matrix have been prepared by high temperature thermal annealing (1000-1250 degrees C) of substoichiometric SiOx films deposited by plasma-enhanced chemical vapor deposition (PECVD). Different techniques have been used to examine the optical and structural properties of Si-nc. Transmission electron microscopy analysis shows the formation of nanocrystals whose sizes are dependent on annealing conditions and deposition parameters. The spectral positions of room temperature photoluminescence are systematically blue shifted with reduction in the size of Si-nc obtained by decreasing the annealing temperature or the Si content during the PECVD deposition. A similar trend has been found in optical absorption measurements. X-ray absorption fine structure measurements indicate the presence of an intermediate region between the Si-nc and the SiO2 matrix that participates in the light emission process. Theoretical observations reported here support these findings. All these efforts allow us to study the link between dimensionality, optical properties, and the local environment of Si-nc and the surrounding SiO2 matrix.

  18. Optimization of silicon oxynitrides by plasma-enhanced chemical vapor deposition for an interferometric biosensor

    NASA Astrophysics Data System (ADS)

    Choo, Sung Joong; Lee, Byung-Chul; Lee, Sang-Myung; Park, Jung Ho; Shin, Hyun-Joon

    2009-09-01

    In this paper, silicon oxynitride layers deposited with different plasma-enhanced chemical vapor deposition (PECVD) conditions were fabricated and optimized, in order to make an interferometric sensor for detecting biochemical reactions. For the optimization of PECVD silicon oxynitride layers, the influence of the N2O/SiH4 gas flow ratio was investigated. RF power in the PEVCD process was also adjusted under the optimized N2O/SiH4 gas flow ratio. The optimized silicon oxynitride layer was deposited with 15 W in chamber under 25/150 sccm of N2O/SiH4 gas flow rates. The clad layer was deposited with 20 W in chamber under 400/150 sccm of N2O/SiH4 gas flow condition. An integrated Mach-Zehnder interferometric biosensor based on optical waveguide technology was fabricated under the optimized PECVD conditions. The adsorption reaction between bovine serum albumin (BSA) and the silicon oxynitride surface was performed and verified with this device.

  19. Characterization of low-temperature silicon nitride films produced by inductively coupled plasma chemical vapor deposition

    SciTech Connect

    Xu, Q.; Ra, Y.; Bachman, M.; Li, G. P.

    2009-01-15

    Silicon nitride films were synthesized at 170 deg. C by using inductively coupled plasma chemical vapor deposition under three microwave power conditions of 500, 800, and 1000 W. The chemical, physical and electrical properties of the deposited silicon nitride films were characterized by Fourier transform infrared, wet etching, atomic force microscopy, ellipsometry, J-V, and C-V measurements of metal-insulator-semiconductor. The microwave power for film deposition is found to play an important role at the films' properties. A high microwave power reduces the retention of hydrogen in a form of Si-H and N-H atomic bonds. The microwave power significantly affects the density of pin holes; the 800 W film has the lowest density of pin holes. In general, the low-temperature silicon nitride films possess better surface roughness than the conventional silicon nitride films produced at higher temperatures. The low-temperature silicon nitride films exhibit an abrupt breakdown, a characteristic of avalanche breakdown. The variation in breakdown strength is correlated with the change in pin-hole density, and the 800 W silicon nitride film possesses the highest breakdown strength. The microwave power has limited influences on leakage current and resistivity of the films. All the low-temperature silicon nitride films are characterized by high-density fixed charges and interface charge traps, of which both densities vary slightly with the microwave power for film deposition.

  20. Thickness-dependent stress in plasma-deposited silicon dioxide films

    NASA Astrophysics Data System (ADS)

    Au, V.; Charles, C.; Bulla, D. A. P.; Love, J. D.; Boswell, R. W.

    2005-04-01

    Thick silicon dioxide (SiO2) films up to 5 μm have been deposited by helicon activated reactive evaporation (plasma assisted deposition with electron beam evaporation source) as both bilayer and trilayer structures, and the film stress was investigated in the context of optical waveguide fabrication. A model for stress in the SiO2-Si bilayer as a function of film thickness is formulated and interpreted in terms of Volmer-Weber film growth mechanisms. We find that island coalescence begins at a film thickness of less than 165 nm and continues until about 700 nm. Above approximately 1 μm thickness, the film continues growth as a continuous film. The stress in a deposited SiO2 film in an SiO2-Si-SiO2 trilayer structure was investigated by adapting the established Stoney's equation for a trilayer system, and comparing it with a thermally grown SiO2 trilayer. A constant value of stress is obtained for the deposited SiO2 film for film thickness >1μm which was consistently less than both measured and previously reported values of stress in thermally grown SiO2.

  1. Deposition of titanium nitride layers by electric arc - Reactive plasma spraying method

    NASA Astrophysics Data System (ADS)

    Şerban, Viorel-Aurel; Roşu, Radu Alexandru; Bucur, Alexandra Ioana; Pascu, Doru Romulus

    2013-01-01

    Titanium nitride (TiN) is a ceramic material which possesses high mechanical properties, being often used in order to cover cutting tools, thus increasing their lifetime, and also for covering components which are working in corrosive environments. The paper presents the experimental results on deposition of titanium nitride coatings by a new combined method (reactive plasma spraying and electric arc thermal spraying). In this way the advantages of each method in part are combined, obtaining improved quality coatings in the same time achieving high productivity. Commercially pure titanium wire and C45 steel as substrate were used for experiments. X-ray diffraction analysis shows that the deposited coatings are composed of titanium nitride (TiN, Ti2N) and small amounts of Ti3O. The microstructure of the deposited layers, investigated both by optical and scanning electron microscopy, shows that the coatings are dense, compact, without cracks and with low porosity. Vickers microhardness of the coatings presents maximum values of 912 HV0.1. The corrosion tests in 3%NaCl solution show that the deposited layers have a high corrosion resistance compared to unalloyed steel substrate.

  2. Effect of Low-Energy Ions on Plasma-Enhanced Deposition of Cubic Boron Nitride

    NASA Astrophysics Data System (ADS)

    Torigoe, M.; Fukui, S.; Teii, K.; Matsumoto, S.

    2015-09-01

    The effect of low-energy ions on deposition of cubic boron nitride (cBN) films in an inductively coupled plasma with the chemistry of fluorine is studied in terms of ion energy, ion flux, and ion to boron flux ratio onto the substrate. The ion energy and the ion to boron flux ratio are determined from the sheath potential and the ratio of incident ion flux to net deposited boron flux, respectively. For negative substrate biases where sp2-bonded BN phase only or no deposit is formed, both the ion energy and the ion to boron flux ratio are high. For positive substrate biases where cBN phase is formed, the ion energy and the ion to boron flux ratio are estimated in the range of a few eV to 35 eV and 100 to 130, respectively. The impact of negative ions is presumed to be negligible due to their low kinetic energy relative to the sheath potential over the substrate surface. The impact of positive ions with high ion to boron flux ratios is primarily responsible for reduction of the ion energy for cBN film deposition. Work supported in part by a Grant-in-Aid for Scientific Research (B), a Funding Program for Next Generation World-Leading Researchers, and an Industrial Technology Research Grant Program 2008.

  3. Properties of AlN films deposited by reactive ion-plasma sputtering

    SciTech Connect

    Bert, N. A.; Bondarev, A. D.; Zolotarev, V. V.; Kirilenko, D. A.; Lubyanskiy, Ya. V.; Lyutetskiy, A. V.; Slipchenko, S. O.; Petrunov, A. N.; Pikhtin, N. A. Ayusheva, K. R.; Arsentyev, I. N.; Tarasov, I. S.

    2015-10-15

    The properties of SiO{sub 2}, Al{sub 2}O{sub 3}, and AlN dielectric coatings deposited by reactive ion-plasma sputtering are studied. The refractive indices of the dielectric coatings are determined by optical ellipsometry. It is shown that aluminum nitride is the optimal material for achieving maximum illumination of the output mirror of a semiconductor laser. A crystalline phase with a hexagonal atomic lattice and oxygen content of up to 10 at % is found by transmission electron microscopy in the aluminum-nitride films. It is found that a decrease in the concentration of residual oxygen in the chamber of the reactive ion-plasma sputtering installation makes it possible to eliminate the appearance of vertical pores in the bulk of the aluminum-nitride film.

  4. Helicon mode formation and radio frequency power deposition in a helicon-produced plasma

    SciTech Connect

    Niemi, K.; Kraemer, M.

    2008-07-15

    Time- and space-resolved magnetic (B-dot) probe measurements in combination with measurements of the plasma parameters were carried out to investigate the relationship between the formation and propagation of helicon modes and the radio frequency (rf) power deposition in the core of a helicon plasma. The Poynting flux and the absorbed power density are deduced from the measured rf magnetic field distribution in amplitude and phase. Special attention is devoted to the helicon absorption under linear and nonlinear conditions. The present investigations are attached to recent observations in which the nonlinear nature of the helicon wave absorption has been demonstrated by showing that the strong absorption of helicon waves is correlated with parametric excitation of electrostatic fluctuations.

  5. A capacitive probe with shaped probe bias for ion flux measurements in depositing plasmas

    SciTech Connect

    Petcu, M. C.; Bronneberg, A. C.; Sarkar, A.; Creatore, M.; Sanden, M. C. M. van de; Blauw, M. A.

    2008-11-15

    The application of a pulse shaped biasing method implemented to a capacitive probe is described. This approach delivers an accurate and simple way to determine ion fluxes in diverse plasma mixtures. To prove the reliability of the method, the ion probe was used in a different configuration, namely, a planar Langmuir probe. In this configuration, the ion current was directly determined from the I-V characteristic and compared with the ion current measured with the pulse shaped ion probe. The results from both measurements are in excellent agreement. It is demonstrated that the capacitive probe is able to perform spatially resolved ion flux measurements under high deposition rate conditions (2-20 nm/s) in a remote expanding thermal plasma in Ar/NH{sub 3}/SiH{sub 4} mixture.

  6. MHD Modelling of Flow Phenomena during the Impulse Plasma Deposition Process

    SciTech Connect

    Rabinski, M.; Zdunek, K.

    2008-03-19

    The paper presents recent computational studies of plasma dynamics in a coaxial accelerator used in surface engineering for Impulse Plasma Deposition (IPD). In our earlier studies we proposed a schematic pattern of a discharge region and a physical model of dynamic phenomena in the IPD accelerator with a tubular external electrode. The simplified snow plow code of our previous studies assumes that all the swept up mass is compressed into an infinitely thin layer immediately behind the shock. In the presented work the complete two-dimensional two-fluid magnetohydrodynamic model has been applied to investigate the sweeping of the working gas by the moving layer as well as the details of phenomena that take place behind a current sheet.

  7. Computational modelling of discharges within the impulse plasma deposition accelerator with a gas valve

    NASA Astrophysics Data System (ADS)

    Rabiński, Marek; Choduń, Rafał; Nowakowska-Langier, Katarzyna; Zdunek, Krzysztof

    2014-05-01

    The paper presents computational studies of working medium dynamics during the impulse plasma deposition (IPD) process when the electric discharge in an interelectrode region is initiated by a gas introduced through a fast-acting valve. During the computational simulations the influence of different discharge parameters on the plasma dynamics was studied. The optimization of the device includes the calculation of the current sheath movement and the sensibility analysis of its dynamics to geometrical and operational parameters. It was found that gas injection can be considered as a useful tool in optimization of the coatings obtained with the IPD technique. Computer simulation results indicate the direction of changes in the development and application of the analysed surface engineering method.

  8. MHD Modelling of Flow Phenomena during the Impulse Plasma Deposition Process

    NASA Astrophysics Data System (ADS)

    Rabiński, M.; Zdunek, K.

    2008-03-01

    The paper presents recent computational studies of plasma dynamics in a coaxial accelerator used in surface engineering for Impulse Plasma Deposition (IPD). In our earlier studies we proposed a schematic pattern of a discharge region and a physical model of dynamic phenomena in the IPD accelerator with a tubular external electrode. The simplified snow plow code of our previous studies assumes that all the swept up mass is compressed into an infinitely thin layer immediately behind the shock. In the presented work the complete two-dimensional two-fluid magnetohydrodynamic model has been applied to investigate the sweeping of the working gas by the moving layer as well as the details of phenomena that take place behind a current sheet.

  9. Graphene layer growth on silicon substrates with nickel film by pulse arc plasma deposition

    SciTech Connect

    Fujita, K.; Banno, K.; Aryal, H. R.; Egawa, T.

    2012-10-15

    Carbon layer has been grown on a Ni/SiO{sub 2}/Si(111) substrate under high vacuum pressure by pulse arc plasma deposition. From the results of Raman spectroscopy for the sample, it is found that graphene was formed by ex-situ annealing of sample grown at room temperature. Furthermore, for the sample grown at high temperature, graphene formation was shown and optimum temperature was around 1000 Degree-Sign C. Transmission electron microscopy observation of the sample suggests that the graphene was grown from step site caused by grain of Ni film. The results show that the pulse arc plasma technique has the possibility for acquiring homogenous graphene layer with controlled layer thickness.

  10. Fabrication of Nanosized Lanthanum Zirconate Powder and Deposition of Thermal Barrier Coating by Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Jagdeesh, N.; Pathak, L. C.

    2016-07-01

    The present manuscript discusses our findings on fabrication of nanosized lanthanum zirconate powder for thermal barrier coating application and its coating by plasma spray on nickel-based superalloy substrate. Single-phase La2Zr2O7 coating of thickness of the order of 45 µm on the Ni-Cr-Al bond coat coated Ni-based superalloy substrate was deposited by plasma spray process. The layers at the interface did not show spallation and inter diffusion was very less. The microstructure, interface, porosity, and mechanical properties of different layers are investigated. The lanthanum zirconate hardness and modulus were 10.5 and 277 GPa, respectively. The load depth curve for lanthanum zirconate showed good elastic recovery around 74%.

  11. Single-electron devices fabricated using double-angle deposition and plasma oxidation

    NASA Astrophysics Data System (ADS)

    Hong, Y.; Barcikowski, Z. S.; Ramanayaka, A. N.; Stewart, M. D., Jr.; Zimmerman, N. M.; Pomeroy, J. M.; Quantum Processes; Metrology Group Team

    We report on development of plasma oxidized, single-electron transistors (SETs) where we seek low-capacitance and small-area Al/AlOx/Al tunnel junctions with small charge offset drift. Performance of metal-based SET quantum devices and superconducting devices has suffered from long-term charge offset drift, high defect densities and charge noise. We use plasma oxidation to lower defect densities of the oxide layer, and adjustable deposition angles to control the overlapping areas for Al/AlOx/Al tunnel junctions. Current-voltage and charge offset drift measurements are planned for cryogenic temperatures. Other electrical properties will be measured at room temperature. We hope to see Coulomb blockade oscillations on these devices and better charge offset stability than typical Al/AlOx/Al SETs.

  12. Vacuum-vapor-deposited films based on benzo(a)phenoxazine derivatives under surface plasma fluorination

    NASA Astrophysics Data System (ADS)

    Agabekov, Vladimir E.; Ignasheva, Olga E.; Belyatsky, Vladimir N.

    1997-07-01

    Modification of vacuum vapor deposited thin films based on benzo(a)phenoxazone-5 derivatives with C3F8 and SF6 plasma were investigated. X-ray photoelectron spectroscopy (XPS) method was used to identify and study the distribution of surface functional groups of untreated and fluorinated films investigated. It was shown that fluor content in element composition of surface film layers and perfluorocarbon group content in Cls-lines of XP-spectra depended on chemical structure of the initial compounds. The more quantity and size of side substitutes were contained in the compound chemical structure the less was the content of fluor and perfluorocarbon groups in film surface fluorinated layer. The probable way of plasma active particle interaction with film surface is discussed. Using Kaelbe's method the influence of treatment conditions and initial compound chemical structure on surface properties of fluorinated films was studied.

  13. Interface Electronic State Characterization of Plasma Enhanced Atomic Layer Deposited Dielectrics on GaN

    NASA Astrophysics Data System (ADS)

    Yang, Jialing

    In this dissertation, the interface chemistry and electronic structure of plasma-enhanced atomic layer deposited (PEALD) dielectrics on GaN are investigated with x-ray and ultraviolet photoemission spectroscopy (XPS and UPS). Three interrelated issues are discussed in this study: (1) PEALD dielectric growth process optimization, (2) interface electronic structure of comparative PEALD dielectrics on GaN, and (3) interface electronic structure of PEALD dielectrics on Ga- and N-face GaN. The first study involved an in-depth case study of PEALD Al2O3 growth using dimethylaluminum isopropoxide, with a special focus on oxygen plasma effects. Saturated and self-limiting growth of Al2O3 films were obtained with an enhanced growth rate within the PEALD temperature window (25--220 °C). The properties of Al2O3 deposited at various temperatures were characterized to better understand the relation between the growth parameters and film properties. In the second study, the interface electronic structures of PEALD dielectrics on Ga-face GaN films were measured. Five promising dielectrics (Al2O3, HfO2, SiO2, La2O 3, and ZnO) with a range of band gap energies were chosen. Prior to dielectric growth, a combined wet chemical and in-situ H 2/N2 plasma clean process was employed to remove the carbon contamination and prepare the surface for dielectric deposition. The surface band bending and band offsets were measured by XPS and UPS for dielectrics on GaN. The trends of the experimental band offsets on GaN were related to the dielectric band gap energies. In addition, the experimental band offsets were near the calculated values based on the charge neutrality level model. The third study focused on the effect of the polarization bound charge of the Ga- and N-face GaN on interface electronic structures. A surface pretreatment process consisting of a NH4OH wet chemical and an in-situ NH3 plasma treatment was applied to remove carbon contamination, retain monolayer oxygen coverage, and

  14. Mechanisms of degradation and failure in a plasma deposited thermal barrier coating

    NASA Technical Reports Server (NTRS)

    Demasi-Marcin, Jeanine T.; Sheffler, Keith D.; Bose, Sudhangshu

    1989-01-01

    Failure of a two layer plasma deposited thermal barrier coating is caused by cyclic thermal exposure and occurs by spallation of the outer ceramic layer. Spallation life is quantitatively predictable, based on the severity of cyclic thermal exposure. This paper describes and attempts to explain unusual constitutive behavior observed in the insulative ceramic coating layer, and presents details of the ceramic cracking damage accumulation process which is responsible for spallation failure. Comments also are offered to rationalize the previously documented influence of interfacial oxidation on ceramic damage accumulation and spallation life.

  15. Plasma-enhanced atomic layer deposition and etching of high-k gadolinium oxide

    SciTech Connect

    Vitale, Steven A.; Wyatt, Peter W.; Hodson, Chris J.

    2012-01-15

    Atomic layer deposition (ALD) of high-quality gadolinium oxide thin films is achieved using Gd(iPrCp){sub 3} and O{sub 2} plasma. Gd{sub 2}O{sub 3} growth is observed from 150 to 350 deg. C, though the optical properties of the film improve at higher temperature. True layer-by-layer ALD growth of Gd{sub 2}O{sub 3} occurred in a relatively narrow window of temperature and precursor dose. A saturated growth rate of 1.4 A/cycle was observed at 250 deg. C. As the temperature increases, high-quality films are deposited, but the growth mechanism appears to become CVD-like, indicating the onset of precursor decomposition. At 250 deg. C, the refractive index of the film is stable at {approx}1.80 regardless of other deposition conditions, and the measured dispersion characteristics are comparable to those of bulk Gd{sub 2}O{sub 3}. XPS data show that the O/Gd ratio is oxygen deficient at 1.3, and that it is also very hygroscopic. The plasma etching rate of the ALD Gd{sub 2}O{sub 3} film in a high-density helicon reactor is very low. Little difference is observed in etching rate between Cl{sub 2} and pure Ar plasmas, suggesting that physical sputtering dominates the etching. A threshold bias power exists below which etching does not occur; thus it may be possible to etch a metal gate material and stop easily on the Gd{sub 2}O{sub 3} gate dielectric. The Gd{sub 2}O{sub 3} film has a dielectric constant of about 16, exhibits low C-V hysteresis, and allows a 50 x reduction in gate leakage compared to SiO{sub 2}. However, the plasma enhanced atomic layer deposition (PE-ALD) process causes formation of an {approx}1.8 nm SiO{sub 2} interfacial layer, and generates a fixed charge of -1.21 x 10{sup 12} cm{sup -2}, both of which may limit use of PE-ALD Gd{sub 2}O{sub 3} as a gate dielectric.

  16. Fabrication of transparent antifouling thin films with fractal structure by atmospheric pressure cold plasma deposition.

    PubMed

    Miyagawa, Hayato; Yamauchi, Koji; Kim, Yoon-Kee; Ogawa, Kazufumi; Yamaguchi, Kenzo; Suzaki, Yoshifumi

    2012-12-21

    Antifouling surface with both superhydrophobicity and oil-repellency has been fabricated on glass substrate by forming fractal microstructure(s). The fractal microstructure was constituted by transparent silica particles of 100 nm diameter and transparent zinc-oxide columns grown on silica particles by atmospheric pressure cold plasma deposition. The sample surface was coated with a chemically adsorbed monomolecular layer. We found that one sample has the superhydrophobic ability with a water droplet contact angle of more than 150°, while another sample has a high transmittance of more than 85% in a wavelength range from 400 to 800 nm.

  17. The effect of diborane additive on the plasma-chemical properties of deposited carbon films

    NASA Astrophysics Data System (ADS)

    Shubina, E. N.; Karasev, P. A.; Titov, A. I.; Podsvirov, O. A.; Vinogradov, A. Ya.; Karasev, N. N.; Pozdnyakov, A. V.

    2017-01-01

    We present the results of studies of the optical, electrical, and mechanical properties of diamondlike carbon films prepared by plasma-chemical vapor deposition from a mixture of methane and diborane in various proportions. Upon reaching the threshold concentration ( 12%) of diborane in the mixture, inclusions of a new phase start to form in the structure of the films. This leads to nonlinear dependence of the interior stresses and the surface resistance of coatings on the composition of the mixture with minimum values corresponding to a diborane concentration of about 12%.

  18. High T(sub c) superconductors fabricated by plasma aerosol mist deposition technique

    NASA Technical Reports Server (NTRS)

    Wang, X. W.; Vuong, K. D.; Leone, A.; Shen, C. Q.; Williams, J.; Coy, M.

    1995-01-01

    We report new results on high T(sub c) superconductors fabricated by a plasma aerosol mist deposition technique, in atmospheric environment. Materials fabricated are YBaCuO, BiPbSrCaCuO, BaCaCuO precursor films for TlBaCaCuO, and other buffers such as YSZ. Depending on processing conditions, sizes of crystallites and/or particles are between dozens of nano-meters and several micrometers. Superconductive properties and other material characteristics can also be tailored.

  19. Large-Area, Plasma-Assisted, Halogen-Based Diamond Deposition

    DTIC Science & Technology

    1992-03-04

    DTIC AD-A247 423 TIC RESEARCH TRIANGLE INSTITUTE RTI/5123/91-92 Quarterly March 1992 LARGE-AREA, PLASMA-ASSISTED, HALOGEN-BASED DIAMOND DEPOSITION...Quarterly Report - First and Second Quarters R.A. Rudder R.J. Markunas M.J. Mantini G.C. Hudson Office of Naval Research Program No. N00014-91-C-0177...fir , : u ____ 92-06469 POST OFFICE BOX 12194 RESEARCH TRIANGLE PARK NORTH CAROLINA 27709 2194 REPORT DOCUMENT PAGE Form Approved )OMB No 0704

  20. Structure of carbon nanotubes grown by microwave-plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Okai, M.; Muneyoshi, T.; Yaguchi, T.; Sasaki, S.

    2000-11-01

    Carbon nanotubes grown on a Ni substrate and an Fe-Ni-Cr alloy substrate by plasma-enhanced chemical vapor deposition were investigated by transmission electron microscope (TEM) and energy dispersive x-ray (EDX) analysis. TEM showed that the nanotubes on both substrates have a piled-cone structure with metal particles on top which determine the diameter of the nanotubes. Their diameter ranges from 60 to 80 nm. Moreover, EDX showed that the metal particles are composed of Ni when the nanotubes are grown on Ni substrate and of Fe and Ni in the case of the Fe-Ni-Cr alloy substrate.

  1. Amorphous hollow carbon spheres synthesized using radio frequency plasma-enhanced chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Yang, G. M.; Xu, Q.; Tian, H. W.; Wang, X.; Zheng, W. T.

    2008-10-01

    We report a method to synthesize amorphous hollow carbon spheres, with diameters ranging from 100 to 800 nm, which are dispersed among bent graphitized carbon nanotubes using radio frequency plasma-enhanced chemical vapour deposition in mixed CH4/H2 gases. The products are characterized by techniques including scanning electron microscopy, energy-dispersive x-ray spectroscopy, Raman spectroscopy and transmission electron microscopy. It is found that MgO and Ni nanoparticles together with hydrogen play important roles in the formation of the spheres. A possible formation mechanism for the carbon composites has been proposed.

  2. Deposition of nanostructured photocatalytic zinc ferrite films using solution precursor plasma spraying

    SciTech Connect

    Dom, Rekha; Sivakumar, G.; Hebalkar, Neha Y.; Joshi, Shrikant V.; Borse, Pramod H.

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Highly economic solution precursor route capable of producing films/coating even for mass scale production. Black-Right-Pointing-Pointer Pure spinel phase ZnFe{sub 2}O{sub 4} porous, immobilized films deposited in single step. Black-Right-Pointing-Pointer Parameter optimization yields access to nanostructuring in SPPS method. Black-Right-Pointing-Pointer The ecofriendly immobilized ferrite films were active under solar radiation. Black-Right-Pointing-Pointer Such magnetic system display advantage w.r.t. recyclability after photocatalyst extraction. -- Abstract: Deposition of pure spinel phase, photocatalytic zinc ferrite films on SS-304 substrates by solution precursor plasma spraying (SPPS) has been demonstrated for the first time. Deposition parameters such as precursor solution pH, concentration, film thickness, plasma power and gun-substrate distance were found to control physico-chemical properties of the film, with respect to their crystallinity, phase purity, and morphology. Alkaline precursor conditions (7 < pH {<=} 10) were found to favor oxide film formation. The nanostructured films produced under optimized conditions, with 500 mM solution at pH {approx} 8.0, yielded pure cubic phase ZnFe{sub 2}O{sub 4} film. Very high/low precursor concentrations yielded mixed phase, less adherent, and highly inhomogeneous thin films. Desired spinel phase was achieved in as-deposited condition under appropriately controlled spray conditions and exhibited a band gap of {approx}1.9 eV. The highly porous nature of the films favored its photocatalytic performance as indicated by methylene blue de-coloration under solar radiation. These immobilized films display good potential for visible light photocatalytic applications.

  3. Study on re-sputtering during CN{sub x} film deposition through spectroscopic diagnostics of plasma

    SciTech Connect

    Liang, Peipei; Yang, Xu; Li, Hui; Cai, Hua; Sun, Jian; Xu, Ning; Wu, Jiada

    2015-10-15

    A nitrogen-carbon plasma was generated during the deposition of carbon nitride (CN{sub x}) thin films by pulsed laser ablation of a graphite target in a discharge nitrogen plasma, and the optical emission of the generated nitrogen-carbon plasma was measured for the diagnostics of the plasma and the characterization of the process of CN{sub x} film deposition. The nitrogen-carbon plasma was recognized to contain various species including nitrogen molecules and molecular ions excited in the ambient N{sub 2} gas, carbon atoms and atomic ions ablated from the graphite target and CN radicals. The temporal evolution and spatial distribution of the CN emission and their dependence on the substrate bias voltage show two groups of CN radicals flying in opposite directions. One represents the CN radicals formed as the products of the reactions occurring in the nitrogen-carbon plasma, revealing the reactive deposition of CN{sub x} film due to the reactive expansion of the ablation carbon plasma in the discharge nitrogen plasma and the effective formation of gaseous CN radicals as precursors for CN{sub x} film growth. The other one represents the CN radicals re-sputtered from the growing CN{sub x} film by energetic plasma species, evidencing the re-sputtering of the growing film accompanying film growth. And, the re-sputtering presents ion-induced sputtering features.

  4. Photocatalytic Functional Coating of TiO2 Thin Film Deposited by Cyclic Plasma Chemical Vapor Deposition at Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Kwon, Jung-Dae; Rha, Jong-Joo; Nam, Kee-Seok; Park, Jin-Seong

    2011-08-01

    Photocatalytic TiO2 thin films were prepared with titanium tetraisopropoxide (TTIP) using cyclic plasma chemical vapor deposition (CPCVD) at atmospheric pressure. The CPCVD TiO2 films contain carbon-free impurities up to 100 °C and polycrystalline anatase phases up to 200 °C, due to the radicals and ion-bombardments. The CPCVD TiO2 films have high transparency in the visible wavelength region and absorb wavelengths below 400 nm (>3.2 eV). The photocatalytic effects of the CPCVD TiO2 and commercial sprayed TiO2 films were measured by decomposing methylene blue (MB) solution under UV irradiation. The smooth CPCVD TiO2 films showed a relatively lower photocatalytic efficiency, but superior catalyst-recycling efficiency, due to their high adhesion strength on the substrates. This CPCVD technique may provide the means to produce photocatalytic thin films with low cost and high efficiency, which would be a reasonable candidate for practical photocatalytic applications, because of the reliability and stability of their photocatalytic efficiency in a practical environment.

  5. Influence of atomic layer deposition valve temperature on ZrN plasma enhanced atomic layer deposition growth

    SciTech Connect

    Muneshwar, Triratna Cadien, Ken

    2015-11-15

    Atomic layer deposition (ALD) relies on a sequence of self-limiting surface reactions for thin film growth. The effect of non-ALD side reactions, from insufficient purging between pulses and from precursor self-decomposition, on film growth is well known. In this article, precursor condensation within an ALD valve is described, and the effect of the continuous precursor source from condensate evaporation on ALD growth is discussed. The influence of the ALD valve temperature on growth and electrical resistivity of ZrN plasma enhanced ALD (PEALD) films is reported. Increasing ALD valve temperature from 75 to 95 °C, with other process parameters being identical, decreased both the growth per cycle and electrical resistivity (ρ) of ZrN PEALD films from 0.10 to 0.07 nm/cycle and from 560 to 350 μΩ cm, respectively. Our results show that the non-ALD growth resulting from condensate accumulation is eliminated at valve temperatures close to the pressure corrected boiling point of precursor.

  6. Microwave plasma assisted chemical vapor deposition of ultra-nanocrystalline diamond films

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Shin

    Microwave plasma assisted ultra-nanocrystalline diamond film deposition was investigated using hydrogen deficient, carbon containing argon plasma chemistries with MSU-developed microwave plasma reactors. Ultra-nanocrystalline diamond film deposition on mechanically scratched silicon wafers was experimentally explored over the following input variables: (1) pressure: 60--240Torr, (2) total gas flow rate: 101--642 sccm, (3) input microwave power 732--1518W, (4) substrate temperature: 500°C--770°C, (5) deposition time: 2--48 hours, and (6) N2 impurities 5--2500 ppm. H2 concentrations were less than 9%, while CH 4 concentration was 0.17--1.85%. It was desired to grow films uniformly over 3″ diameter substrates and to minimize the grain size. Large, uniform, intense, and greenish-white discharges were sustained in contact with three inch silicon substrates over a 60--240 Torr pressure regime. At a given operating pressure, film uniformity was controlled by adjusting substrate holder geometry, substrate position, input microwave power, gas chemistries, and total gas flow rates. Film ultra-nanocrystallinity and smoothness required high purity deposition conditions. Uniform ultra-nanocrystalline films were synthesized in low leak-rate system with crystal sizes ranging from 3--30 nm. Films with 11--50 nm RMS roughness and respective thickness values of 1--23 mum were synthesized over 3″ wafers under a wide range of different deposition conditions. Film RMS roughness 7 nm was synthesized with thickness of 430 nm. Film uniformities of almost 100% were achieved over three inch silicon wafers. UV Raman and XRD characterization results indicated the presence of diamond in the synthesized films. Optical Emission Spectroscopy measurements showed that the discharge gas temperature was in excess of 2000 K. The synthesized films are uniformly smooth and the as grown ultra-nanocrystalline diamond can be used for a high frequency SAW device substrate material. IR measurements

  7. Enhanced dielectric deposition on single-layer MoS2 with low damage using remote N2 plasma treatment.

    PubMed

    Qian, Qingkai; Zhang, Zhaofu; Hua, Mengyuan; Tang, Gaofei; Lei, Jiacheng; Lan, Feifei; Xu, Yongkuan; Yan, Ruyue; Chen, Kevin J

    2017-04-28

    Using remote N2 plasma treatment to promote dielectric deposition on the dangling-bond free MoS2 is explored for the first time. The N2 plasma induced damages are systematically studied by the defect-sensitive acoustic-phonon Raman of single-layer MoS2, with samples undergoing O2 plasma treatment as a comparison. O2 plasma treatment causes defects in MoS2 mainly by oxidizing MoS2 along the already defective sites (most likely the flake edges), which results in the layer oxidation of MoS2. In contrast, N2 plasma causes defects in MoS2 mainly by straining and mechanically distorting the MoS2 layers first. Owing to the relatively strong MoS2-substrate interaction and chemical inertness of MoS2 in N2 plasma, single-layer MoS2 shows great stability in N2 plasma and only stable point defects are introduced after long-duration N2 plasma exposure. Considering the enormous vulnerability of single-layer MoS2 in O2 plasma and the excellent stability of single-layer MoS2 in N2 plasma, the remote N2 plasma treatment shows great advantage as surface functionalization to promote dielectric deposition on single-layer MoS2.

  8. Proposal of New Precursors for Plasma-Enhanced Chemical Vapor Deposition of SiOCH Low-k Films with Plasma Damage Resistance

    NASA Astrophysics Data System (ADS)

    Yoshi Ohashi,; Nobuo Tajima,; Yonghua Xu,; Takeshi Kada,; Shuji Nagano,; Hideharu Shimizu,; Satoshi Hasaka,

    2010-05-01

    We propose new precursors for bulk low-k films with plasma damage resistance. Our newly designed precursors contain long-chain hydrocarbon groups such as i-butyl and n-propyl groups. Using these precursors, we successfully produced films containing Si-CH2-Si groups by plasma-enhanced chemical vapor deposition (PECVD). The plasma damage resistance of these films under NH3 plasma treatment was studied. It was found that the increase in the k-value (Δ k) is smaller in films with more Si-CH2-Si groups.

  9. Proposal of New Precursors for Plasma-Enhanced Chemical Vapor Deposition of SiOCH Low-k Films with Plasma Damage Resistance

    NASA Astrophysics Data System (ADS)

    Ohashi, Yoshi; Tajima, Nobuo; Xu, Yonghua; Kada, Takeshi; Nagano, Shuji; Shimizu, Hideharu; Hasaka, Satoshi

    2010-05-01

    We propose new precursors for bulk low-k films with plasma damage resistance. Our newly designed precursors contain long-chain hydrocarbon groups such as i-butyl and n-propyl groups. Using these precursors, we successfully produced films containing Si-CH2-Si groups by plasma-enhanced chemical vapor deposition (PECVD). The plasma damage resistance of these films under NH3 plasma treatment was studied. It was found that the increase in the k-value (Δk) is smaller in films with more Si-CH2-Si groups.

  10. In-situ monitoring of plasma ion assisted deposition (PIAD) processes

    NASA Astrophysics Data System (ADS)

    Harhausen, Jens; Foest, Rüdiger; Loffhagen, Detlef

    2015-09-01

    Present photonics applications depend on accurate production techniques. Plasma based processes might be termed the backbone of multilayer optical coatings which are the key components of dielectric mirrors, filters or antireflectives. However, the sector strongly relies on process recipies based on empirical optimization of thin film properties. Limitations in quality, repeatability and yield are faced. In this contribution results of efforts on plasma characterization of a beam source employed for PIAD are presented. Data on electron and ion kinetics as well as optical emission facilitated a comprehensive understanding of underlying physics of ion beam generation and propagation in an industrial type batch coater. In order to promote the development of next generation production plants, concepts for in-situ diagnostics are investigated. Results from monitoring of optical radiance of the plasma plume near the source and electron density near the substrates are discussed. The novel concept of the multipole resonance probe is applied during deposition in order to trace variations not only in magnitude of plasma density, but also its spatial distribution. Coating materials comprise TiO2, Ta2O5, Al2O3 and SiO2. Funded by the German Federal Ministry of Education and Research (BMBF) under Grant 13N13213).

  11. Modeling of Sheath Ion-Molecule Reactions in Plasma Enhanced Chemical Vapor Deposition of Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hash, David B.; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    In many plasma simulations, ion-molecule reactions are modeled using ion energy independent reaction rate coefficients that are taken from low temperature selected-ion flow tube experiments. Only exothermic or nearly thermoneutral reactions are considered. This is appropriate for plasma applications such as high-density plasma sources in which sheaths are collisionless and ion temperatures 111 the bulk p!asma do not deviate significantly from the gas temperature. However, for applications at high pressure and large sheath voltages, this assumption does not hold as the sheaths are collisional and ions gain significant energy in the sheaths from Joule heating. Ion temperatures and thus reaction rates vary significantly across the discharge, and endothermic reactions become important in the sheaths. One such application is plasma enhanced chemical vapor deposition of carbon nanotubes in which dc discharges are struck at pressures between 1-20 Torr with applied voltages in the range of 500-700 V. The present work investigates The importance of the inclusion of ion energy dependent ion-molecule reaction rates and the role of collision induced dissociation in generating radicals from the feedstock used in carbon nanotube growth.

  12. Vapor phase reactions in polymerization plasma for divinylsiloxane-bis-benzocyclobutene film deposition

    SciTech Connect

    Kinoshita, Keizo; Nakano, Akinori; Kawahara, Jun; Kunimi, Nobutaka; Hayashi, Yoshihiro; Kiso, Osamu; Saito, Naoaki; Nakamura, Keiji; Kikkawa, Takamaro

    2006-11-15

    Vapor phase reactions in plasma polymerization of divinylsiloxane-bis-benzocyclobutene (DVS-BCB) low-k film depositions on 300 mm wafers were studied using mass spectrometry, in situ Fourier transform infrared, and a surface wave probe. Polymerization via Diels-Alder cycloaddition reaction was identified by the detection of the benzocyclohexene group. Hydrogen addition and methyl group desorption were also detected in DVS-BCB monomer and related large molecules. The dielectric constant k of plasma polymerized DVS-BCB with a plasma source power range up to 250 W was close to {approx}2.7 of thermally polymerized DVS-BCB, and increased gradually over 250 W. The electron density at 250 W was about 1.5x10{sup 10} cm{sup -3}. The increase of the k value at higher power was explained by the decrease of both large molecular species via multistep dissociation and incorporation of silica components into the polymer. It was found that the reduction of electron density as well as precursor residence time is important for the plasma polymerization process to prevent the excess dissociation of the precursor.

  13. Plasma interactions determine the composition in pulsed laser deposited thin films

    SciTech Connect

    Chen, Jikun; Stender, Dieter; Conder, Kazimierz; Wokaun, Alexander; Schneider, Christof W.; Lippert, Thomas; Döbeli, Max

    2014-09-15

    Plasma chemistry and scattering strongly affect the congruent, elemental transfer during pulsed laser deposition of target metal species in an oxygen atmosphere. Studying the plasma properties of La{sub 0.6}Sr{sub 0.4}MnO{sub 3}, we demonstrate for as grown La{sub 0.6}Sr{sub 0.4}MnO{sub 3-δ} films that a congruent transfer of metallic species is achieved in two pressure windows: ∼10{sup −3} mbar and ∼2 × 10{sup −1} mbar. In the intermediate pressure range, La{sub 0.6}Sr{sub 0.4}MnO{sub 3-δ} becomes cation deficient and simultaneously almost fully stoichiometric in oxygen. Important for thin film growth is the presence of negative atomic oxygen and under which conditions positive metal-oxygen ions are created in the plasma. This insight into the plasma chemistry shows why the pressure window to obtain films with a desired composition and crystalline structure is narrow and requires a careful adjustment of the process parameters.

  14. Vapors and Droplets Mixture Deposition of Metallic Coatings by Very Low Pressure Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Vautherin, B.; Planche, M.-P.; Bolot, R.; Quet, A.; Bianchi, L.; Montavon, G.

    2014-04-01

    In recent years, the very low pressure plasma-spraying (VLPPS) process has been intensely developed and implemented to manufacture thin, dense and finely structured ceramic coatings for various applications, such as Y2O3 for diffusion barriers, among other examples. This paper aims at presenting developments carried out on metallic coatings. Aluminum was chosen as a demonstrative material due to its "moderate" vaporization enthalpy (i.e., 38.23 KJ cm-3) compared to the one of copper (i.e., 55.33 KJ cm-3), cobalt (i.e., 75.03 KJ cm-3), or even tantalum (i.e., 87.18 KJ cm-3). The objective of this work is primarily to better understand the behavior of a solid precursor injected into the plasma jet leading to the formation of vapors and to better control the factors affecting the coating structure. Nearly dense aluminum coatings were successfully deposited by VLPPS at 100 Pa with an intermediate power plasma torch (i.e., Sulzer Metco F4 type gun with maximum power of 45 kW). Optical emission spectroscopy (OES) was implemented to study and analyze the vapor behavior into the plasma jet. Simplified CFD modeling allowed better understanding of some of the thermo-physical mechanisms. The effect of powder-size distribution, substrate temperature and spray distance were studied. The phase composition and microstructural features of the coatings were characterized by XRD and SEM. Moreover, Vickers microhardness measurements were implemented.

  15. Magnetically controlled deposition of metals using gas plasma. Quarterly progress report, October--December 1996

    SciTech Connect

    1997-03-01

    Thin layers of secondary material are plated on substrates either by plating or spraying processes. Plating operations produce large amounts of hazardous liquid waste. Spraying, while one of the less waste intensive methods, produces {open_quotes}over spray{close_quotes} which is waste that is a result of uncontrolled nature of the spray stream. In many cases the over spray produces a hazardous waste. Spray coating is a mature process with many uses. Material can be deposited utilizing spraying technology in three basic ways: {open_quotes}Flame spraying{close_quotes}, direct spraying of molten metals and/or plasma spraying. This project is directed at controlling the plasma spraying process and thereby minimizing the waste generated in that process. The proposed process will utilize a standard plasma spray gunsmith the addition of magnetic fields to focus and control the plasma. In order to keep development cost at a minimum, the project was organized in phases. The first and current phase involves developing an analytical model that will prove the concept and be used to design a prototype. Analyzing the process and using the analysis has the potential to generate significant hardware cost savings.

  16. Magnetically controlled deposition of metals using gas plasma. Quarterly progress report, January 1997--March 1997

    SciTech Connect

    1997-05-01

    Thin layers of secondary material are plated on substrates either by plating or spraying processes. Plating operations produce large amounts of hazardous liquid waste. Spraying, while one of the less waste intensive methods, produces {open_quotes}over spray,{close_quotes} or waste that is a result of uncontrolled nature of the spray stream. In many cases the over spray may produce a hazardous waste, requiring special processing. Spray coating is a mature process with many uses. Material can be deposited utilizing spraying technology in three basic ways: {open_quotes}Flame spraying{close_quotes}, direct spraying of molten metals and/or plasma spraying. This project is directed at controlling the plasma spraying process and thereby minimizing the waste generated in that process. The proposed process will utilize a standard plasma spray gun with the addition of magnetic fields to focus and control the plasma. In order to keep development cost at a minimum, the project was organized in phases. The first and current phase involves developing an analytical model that will prove the concept and be used to design a prototype. Analyzing the process and using the analysis has the potential to generate significant hardware cost savings.

  17. Model of enhanced energy deposition in a Z-pinch plasma

    SciTech Connect

    Velikovich, A. L.; Davis, J.; Thornhill, J. W.; Giuliani, J. L. Jr.; Rudakov, L. I.; Deeney, C.

    2000-08-01

    In numerous experiments, magnetic energy coupled to strongly radiating Z-pinch plasmas exceeds the thermalized kinetic energy, sometimes by a factor of 2-3. An analytical model describing this additional energy deposition based on the concept of macroscopic magnetohydrodynamic (MHD) turbulent pinch heating proposed by Rudakov and Sudan [Phys. Reports 283, 253 (1997)] is presented. The pinch plasma is modeled as a foam-like medium saturated with toroidal ''magnetic bubbles'' produced by the development of surface m=0 Rayleigh-Taylor and MHD instabilities. As the bubbles converge to the pinch axis, their magnetic energy is converted to thermal energy of the plasma through pdV work. Explicit formulas for the average dissipation rate of this process and the corresponding contribution to the resistance of the load, which compare favorably to the experimental data and simulation results, are presented. The possibility of using this enhanced (relative to Ohmic heating) dissipation mechanism to power novel plasma radiation sources and produce high K-shell yields using long current rise time machines is discussed. (c) 2000 American Institute of Physics.

  18. Morphological evolution of self-deposition Bi2Se3 nanosheets by oxygen plasma treatment

    NASA Astrophysics Data System (ADS)

    Jia, Guozhi; Wu, Zengna; Wang, Peng; Yao, Jianghong; Chang, Kai

    2016-02-01

    Bi2Se3 nanosheets were successfully synthesized by a microwave-assisted approach in the presence of polyvinylpyrroli done at a temperature of 180 °C for 2 h. The thin film was prepared on a silicon wafer via a self-deposition process in a Bi2Se3 nanosheet ink solution using the evaporation-induced self-assembly method. The structure and morphology of the obtained products were characterized by X-ray diffraction, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy, and Raman spectroscopy. The highly uniform Bi2Se3 particles could be formed by controlling the oxygen plasma treatment time. After the plasma pretreatment from 10 to 20 s, the surface of Bi2Se3 film evolved from the worm-like structure to particles. The highly uniform thin film was formed on further increasing the plasma treatment time, which is consistent with the observed SEM results. Several important processes can result in the morphological evolution of Bi2Se3 nanosheets: (1) formation of Bi2Se3 oxide layer; (2) self-assembly of oxide nanoparticles under the action of high-energy oxygen plasma; and (3) electrostatic interaction and etching mechanism.

  19. Hollow cathode sustained plasma microjets: Characterization and application to diamond deposition

    NASA Astrophysics Data System (ADS)

    Sankaran, R. Mohan; Giapis, Konstantinos P.

    2002-09-01

    Extending the principle of operation of hollow cathode microdischarges to a tube geometry has allowed the formation of stable, high-pressure plasma microjets in a variety of gases including Ar, He, and H2. Direct current discharges are ignited between stainless steel capillary tubes (d=178 mum) which are operated as the cathode and a metal grid or plate that serves as the anode. Argon plasma microjets can be sustained in ambient air with plasma voltages as low as 260 V for cathode-anode gaps of 0.5 mm. At larger operating voltage, this gap can be extended up to several millimeters. Using a heated molybdenum substrate as the anode, plasma microjets in CH4/H2 mixtures have been used to deposit diamond crystals and polycrystalline films. Micro-Raman spectroscopy of these films shows mainly sp3 carbon content with slight shifting of the diamond peak due to internal stresses. Optical emission spectroscopy of the discharges used in the diamond growth experiments confirms the presence of atomic hydrogen and CH radicals.

  20. Plasma enhanced chemical vapor deposition (PECVD) method of forming vanadium oxide films and vanadium oxide thin-films prepared thereby

    DOEpatents

    Zhang, Ji-Guang; Tracy, C. Edwin; Benson, David K.; Turner, John A.; Liu, Ping

    2000-01-01

    A method is disclosed of forming a vanadium oxide film on a substrate utilizing plasma enhanced chemical vapor deposition. The method includes positioning a substrate within a plasma reaction chamber and then forming a precursor gas comprised of a vanadium-containing chloride gas in an inert carrier gas. This precursor gas is then mixed with selected amounts of hydrogen and oxygen and directed into the reaction chamber. The amounts of precursor gas, oxygen and hydrogen are selected to optimize the final properties of the vanadium oxide film An rf plasma is generated within the reaction chamber to chemically react the precursor gas with the hydrogen and the oxygen to cause deposition of a vanadium oxide film on the substrate while the chamber deposition pressure is maintained at about one torr or less. Finally, the byproduct gases are removed from the plasma reaction chamber.

  1. Low-Temperature Silicon Epitaxy by Remote, Plasma - Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Habermehl, Scott Dwight

    The dynamics of low temperature Si homoepitaxial and heteroepitaxial growth, by remote plasma enhanced chemical vapor deposition, RPECVD, have been investigated. For the critical step of pre-deposition surface preparation of Si(100) surfaces, the attributes of remote plasma generated atomic H are compared to results obtained with a rapid thermal desorption, RTD, technique and a hybrid H-plasma/RTD technique. Auger electron spectroscopy, AES, and electron diffraction analysis indicate the hybrid technique to be very effective at surface passivation, while the RTD process promotes the formation of SiC precipitates, which induce defective epitaxial growth. For GaP and GaAs substrates, the use of atomic H exposure is investigated as a surface passivation technique. AES shows this technique to be effective at producing atomically clean surfaces. For processing at 400^circrm C, the GaAs(100) surface is observed to reconstruct to a c(8 x 2)Ga symmetry while, at 530^ circrm C the vicinal GaP(100) surface, miscut 10^circ , is observed to reconstruct to a (1 x n) type symmetry; an unreconstructed (1 x 1) symmetry is observed for GaP(111). Differences in the efficiency with which native oxides are removed from the surface are attributed to variations in the local atomic bonding order of group V oxides. The microstructure of homoepitaxial Si films, deposited at temperatures of 25-450^circ rm C and pressures of 50-500 mTorr, is catalogued. Optimized conditions for the deposition of low defect, single crystal films are identified. The existence of two pressure dependent regimes for process activation are observed. In-situ mass spectral analysis indicates that the plasma afterglow is dominated by monosilane ions below 200 mTorr, while above 200 mTorr, low mass rm H_{x} ^+ (x = 1,2,3) and rm HHe^+ ions dominate. Consideration of the growth rate data indicates that downstream dissociative silane ionization, in the lower pressure regime, is responsible for an enhanced surface H

  2. Experimental study of fractal clusters formation from nanoparticles synthesized by atmospheric pressure plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Mishin, Maxim V.; Protopopova, Vera S.; Alexandrov, Sergey E.

    2014-11-01

    This paper presents the experimental results from the fractal structures formation from nanoparticles of silicone dioxide deposited on the silicon substrate surface. Nanoparticles are synthesized by atmospheric pressure plasma-enhanced chemical vapor deposition with the use of capacitively coupled radio frequency (13.56 MHz) discharge sustained in helium atmosphere. Tetraethoxysilane is chosen as the test precursor. Correlation between the morphology of obtained deposits and the process parameters is found. The capability of nanoparticles movement along the deposit surface in local near-surface electric field is demonstrated. The empirical model that satisfactorily explained the mechanism of fractal clusters formation from nanoparticles on the substrate surface is developed. The model indicates that the dynamics of deposit morphology variations is determined by two competing processes: electrical charge transfer by nanoparticles to the deposit surface and electrical charge running off over the surface under conditions of changeable conductivity of the deposit surface.

  3. New insights on the effect of hydrogen to tungsten hexafluoride partial pressure ratio on plasma deposited tungsten thin films

    NASA Astrophysics Data System (ADS)

    Kim, Yong Tae; Hong, Jong Sung; Min, Suk-Ki

    1991-12-01

    Resistivities of tungsten thin films deposited by plasma enhanced chemical vapor deposition are very sensitive to the H2/WF6 partial pressure ratio, while the resistivities of tungsten films deposited by low pressure chemical vapor deposition are insensitive to the H2/WF6 ratio. The reason is investigated with x-ray diffraction, transmission electron microscopy, Auger electron spectroscopy and optical emission spectroscopy. As a result, when the H2/WF6 partial pressure ratio is higher than 15, plasma deposited tungsten has a low resistive (11 μΩ cm) bcc structure without F impurities. However, if the H2/WF6 ratios are decreased, porous and β-phase W films are formed due to the incomplete reduction of F concentrations.

  4. Effects of plasma-enhanced chemical vapor deposition (PECVD) on the carrier lifetime of Al2O3 passivation stack

    NASA Astrophysics Data System (ADS)

    Cho, Kuk-Hyun; Cho, Young Joon; Chang, Hyo Sik; Kim, Kyung-Joong; Song, Hee Eun

    2015-09-01

    We investigated the effect on the minority carrier lifetime of atomic layer deposition (ALD) Al2O3 passivation by a plasma-enhanced chemical vapor deposition (PECVD) SiON layer in Si/Al2O3/SiON-passivated structure. The lifetime variation of the Al2O3/SiON stack layer was found to depend on both the plasma power and the deposition temperature during the PECVD SiON process and to show better thermal stability than the Al2O3/SiNx:H stack under the same deposition conditions. The lifetime after a high-temperature firing process was improved dramatically at the PECVD deposition temperature of 200 °C. Our results provide a significant clue to reason for the improvement of the passivation performance for passivated emitter and rear contact (PERC) silicon solar cells.

  5. Temperature dependence of the biaxial modulus, intrinsic stress and composition of plasma deposited silicon oxynitride films

    NASA Technical Reports Server (NTRS)

    Harding, David R.; Ogbuji, Linus U. T.; Freeman, Mathieu J.

    1995-01-01

    Silicon oxynitride films were deposited by plasma-enhanced chemical-vapor deposition. The elemental composition was varied between silicon nitride and silicon dioxide: SiO(0.3)N(1.0), SiO(0.7)N(1.6), SiO(0.7)N(1.1), and SiO(1.7)N(0.%). These films were annealed in air, at temperatures of 40-240 C above the deposition temperature (260 C), to determine the stability and behavior or each composition. the biaxial modulus, biaxial intrinsic stress, and elemental composition were measured at discrete intervals within the annealing cycle. Films deposited from primarily ammonia possessed considerable hydrogen (up to 38 at.%) and lost nitrogen and hydrogen at anneal temperatures (260-300 C) only marginally higher than the deposition temperature. As the initial oxygen content increased a different mechanism controlled the behavior or the film: The temperature threshold for change rose to approximately equal to 350 C and the loss of nitrogen was compensated by an equivalent rise in the oxygen content. The transformation from silicon oxynitride to silica was completed after 50 h at 400 C. The initial biaxial modulus of all compositions was 21-3- GPa and the intrinsic stress was -30 to 85 MPa. Increasing the oxygen content raised the temperature threshold where cracking first occurred; the two film compositions with the highest initial oxygen content did not crack, even at the highest temperature (450 C) investigated. At 450 C the biaxial modulus increased to approximately equal to 100 GPa and the intrinsic stress was approximately equal to 200 MPa. These increases could be correlated with the observed change in the film's composition. When nitrogen was replaced by oxygen, the induced stress remained lower than the biaxial strength of the material, but, when nitrogen and hydrogen were lost, stress-relieving microcracking occurred.

  6. Growth and characterization of radio-frequency plasma deposited gold-carbon composites

    NASA Astrophysics Data System (ADS)

    Flouttard, J. L.; Akinnifesi, J.; Cambril, E.; Despax, B.

    1991-07-01

    Gold-hydrocarbon composite thin films with various metal volume fractions have been deposited by a combination of sputtering and plasma deposition in argon-propane plasma. Partial pressure control and optical spectroscopy of the gas phase have shown the growth processes to be partially dependent on the chemical reactions occurring on the substrate. The polymer matrix structure was analyzed by several techniques and found to consist of dense hydrocarbon with a density of 1.7. For low metal volume fractions, optical spectra of films show that the dielectric nature of the polymer predominates while the metallic phase governs the absorption phenomenon for gold-rich films. Electrical conductivity measurements have revealed the influence of graphitic structures in the film just above a metal volume fraction p=0.03, below which carbon-carbon sp2 bonds are more predominant. Similarly the percolation threshold has been found to occur at about p=0.3 and the conductivity exponent is evaluated at 1.55.

  7. In situ process diagnostics of silane plasma for device-quality a-Si:H deposition

    NASA Astrophysics Data System (ADS)

    Shing, Y. H.; Perry, J. W.; Hermann, A. M.

    Coherent anti-Stokes Raman spectroscopy (CARS) and mass spectrometry (MS) have been applied to in situ process diagnostics of a silane plasma for device-quality a-Si:H film deposition. Silane depletion was directly measured by CARS and is linearly dependent on RF power in the region of 4-12 W with a slope of 0.5 percent/mW-sq cm. The depletion is also dependent on SiH4 flow rate starting with a 50 percent depletion at a low flow rate of 5.6 sccm and asymptotically approaching an 8 percent depletion at a flow rate of 80 sccm. The mass spectral line signal intensity of disilane increases with RF power and shows an apparent transition at 6 W. Disilane formation in silane plasma, film deposition rate, and silane depletion ratio as a function of the RF power indicate that the film growth mechanism in the low-power region of 3.5-6.5 W is substantially different from that in the high-power region of 6.5-12 W.

  8. Thermal and Kerr nonlinear properties of plasma-deposited silicon nitride/ silicon dioxide waveguides.

    PubMed

    Ikeda, Kazuhiro; Saperstein, Robert E; Alic, Nikola; Fainman, Yeshaiahu

    2008-08-18

    We introduce and present experimental evaluations of loss and nonlinear optical response in a waveguide and an optical resonator, both implemented with a silicon nitride/ silicon dioxide material platform prepared by plasma-enhanced chemical vapor deposition with dual frequency reactors that significantly reduce the stress and the consequent loss of the devices. We measure a relatively small loss of approximately 4dB/cm in the waveguides. The fabricated ring resonators in add-drop and all-pass arrangements demonstrate quality factors of Q=12,900 and 35,600. The resonators are used to measure both the thermal and ultrafast Kerr nonlinearities. The measured thermal nonlinearity is larger than expected, which is attributed to slower heat dissipation in the plasma-deposited silicon dioxide film. The n2 for silicon nitride that is unknown in the literature is measured, for the first time, as 2.4 x 10(-15)cm(2)/W, which is 10 times larger than that for silicon dioxide.

  9. Development of dielectric barrier discharge plasma processing apparatus for mass spectrometry and thin film deposition

    SciTech Connect

    Majumdar, Abhijit; Hippler, Rainer

    2007-07-15

    Cost effective and a very simple dielectric barrier discharge plasma processing apparatus for thin film deposition and mass spectroscopic analysis of organic gas mixture has been described. The interesting features of the apparatus are the construction of the dielectric electrodes made of aluminum oxide or alumina (Al{sub 2}O{sub 3}) and glass and the generation of high ignition voltage from the spark plug transformer taken from car. Metal capacitor is introduced in between ground and oscilloscope to measure the executing power during the discharge and the average electron density in the plasma region. The organic polymer films have been deposited on Si (100) substrate using several organic gas compositions. The experimental setup provides a unique drainage system from the reaction chamber controlled by a membrane pump to suck out and remove the poisonous gases or residuals (cyanogens, H-CN, CH{sub x}NH{sub 2}, etc.) which have been produced during the discharge of CH{sub 4}/N{sub 2} mixture.

  10. Structural and chemical analysis of annealed plasma-enhanced atomic layer deposition aluminum nitride films

    SciTech Connect

    Broas, Mikael Vuorinen, Vesa; Sippola, Perttu; Pyymaki Perros, Alexander; Lipsanen, Harri; Sajavaara, Timo; Paulasto-Kröckel, Mervi

    2016-07-15

    Plasma-enhanced atomic layer deposition was utilized to grow aluminum nitride (AlN) films on Si from trimethylaluminum and N{sub 2}:H{sub 2} plasma at 200 °C. Thermal treatments were then applied on the films which caused changes in their chemical composition and nanostructure. These changes were observed to manifest in the refractive indices and densities of the films. The AlN films were identified to contain light element impurities, namely, H, C, and excess N due to nonideal precursor reactions. Oxygen contamination was also identified in the films. Many of the embedded impurities became volatile in the elevated annealing temperatures. Most notably, high amounts of H were observed to desorb from the AlN films. Furthermore, dinitrogen triple bonds were identified with infrared spectroscopy in the films. The triple bonds broke after annealing at 1000 °C for 1 h which likely caused enhanced hydrolysis of the films. The nanostructure of the films was identified to be amorphous in the as-deposited state and to become nanocrystalline after 1 h of annealing at 1000 °C.

  11. Preparation of amorphous electrochromic tungsten oxide and molybdenum oxide by plasma enhanced chemical vapor deposition

    SciTech Connect

    Tracy, C.E.; Benson, D.K.

    1986-09-01

    Preliminary experiments have been performed to probe the feasibility of using plasma enhanced chemical vapor deposition (PE--CVD) to prepare electrochromic thin films of tungsten oxide and molybdenum oxide by plasma reaction of WF/sub 6/, W(CO)/sub 6/, and Mo(CO)/sub 6/ with oxygen. Thin films produced in a 300 W, electrodeless, radio-frequency (rf), capacitive discharge were found to be electrochromic when tested with either liquid or solid electrolytes. Optical spectroscopy was performed on two electrochromic coatings after Li/sup +/ ion insertion from a propylene carbonate liquid electrolyte. Broad absorption peaks at --900 nm for WO/sub 3/ and 600 nm for MoO/sub 3/ were observed. Optical results for PE--CVD MoO/sub 3/ films differ from those reported for evaporated MoO/sub 3/ films which have an absorption peak at --800 nm. The shorter wavelength absorption in the PE--CVD MoO/sub 3/ films offers the potential for fabricating electrochromic devices with higher contrast ratios and less color change. Optical emission spectroscopy, Auger, and x-ray diffraction analyses indicate these thin film deposits to be predominantly amorphous tungsten and molybdenum oxides.

  12. Plasma assisted deposition of single and multistacked TiO2 hierarchical nanotube photoanodes.

    PubMed

    Nicolas Filippin, A; Sanchez-Valencia, Juan R; Idígoras, Jesús; Rojas, T Cristina; Barranco, Angel; Anta, Juan A; Borras, Ana

    2017-04-13

    We present herein an evolved methodology for the growth of nanocrystalline hierarchical nanotubes combining physical vapor deposition of organic nanowires (ONWs) and plasma enhanced chemical vacuum deposition of anatase TiO2 layers. The ONWs act as vacuum removable 1D and 3D templates, with the whole process occurring at temperatures ranging from RT to 250 °C. As a result, a high density of hierarchical nanotubes with tunable diameter, length and tailored wall microstructures are formed on a variety of processable substrates as metal and metal oxide films or nanoparticles including transparent conductive oxides. The reiteration of the process leads to the development of an unprecedented 3D nanoarchitecture formed by stacking the layers of hierarchical TiO2 nanotubes. As a proof of concept, we present the superior performance of the 3D nanoarchitecture as a photoanode within an excitonic solar cell with efficiencies as high as 4.69% for a nominal thickness of the anatase layer below 2.75 μm. Mechanical stability and straightforward implementation in devices are demonstrated at the same time. The process is extendable to other functional oxides fabricated by plasma-assisted methods with readily available applications in energy harvesting and storage, catalysis and nanosensing.

  13. Analysis of grain size in FePt films fabricated using remote plasma deposition

    NASA Astrophysics Data System (ADS)

    Huskisson, D.; Zygridou, S.; Haigh, S. J.; Barton, C. W.; Nutter, P. W.; Thomson, T.

    2017-12-01

    Remote plasma sputtering (RPS) offers a high degree of control over the sputtering parameters used to deposit thin metallic films and has demonstrated a capability to control the media grain size distribution. Narrow grain size distributions remain a key requirement for future magnetic media. Here we report a comprehensive magnetometry, X-ray diffraction and transmission electron microscopy study of how RPS affects the grain size distribution of continuous, non-segregated L10 FePt thin films. These provide a model medium for heat-assisted magnetic recording and more generally for spintronic devices such as magnetoresistive random access memory and spin torque oscillators, where very high perpendicular magnetocrystalline anisotropy is required. Varying the target DC bias voltage, which in RPS can be tuned independently of the plasma generation, produces no meaningful, statistical change in average grain size, 6.5 ± 0.1 nm, for as-deposited, disordered FePt. Annealing at 800 °C creates the well-ordered L10 phase but results in an increased average grain size of 8.3-13.6 nm, and a significantly wider grain size distribution of 6.4-8.5 nm. These results show that whilst RPS is capable of producing well-ordered L10 FePt thin films, it does not offer an advantage in controlling the grain size of FePt, as reported in other thin film systems.

  14. Characterization and performance of carbon films deposited by plasma and ion beam based techniques

    SciTech Connect

    Walter, K C; Kung, H; Levine, T

    1994-12-31

    Plasma and ion beam based techniques have been used to deposit carbon-based films. The ion beam based method, a cathodic arc process, used a magnetically mass analyzed beam and is inherently a line-of-sight process. Two hydrocarbon plasma-based, non-line-of-sight techniques were also used and have the advantage of being capable of coating complicated geometries. The self-bias technique can produce hard carbon films, but is dependent on rf power and the surface area of the target. The pulsed-bias technique can also produce hard carbon films but has the additional advantage of being independent of rf power and target surface area. Tribological results indicated the coefficient of friction is nearly the same for carbon films from each deposition process, but the wear rate of the cathodic arc film was five times less than for the self-bias or pulsed-bias films. Although the cathodic arc film was the hardest, contained the highest fraction of sp{sup 3} bonds and exhibited the lowest wear rate, the cathodic arc film also produced the highest wear on the 440C stainless steel counterface during tribological testing. Thus, for tribological applications requiring low wear rates for both counterfaces, coating one surface with a very hard, wear resistant film may detrimentally affect the tribological behavior of the counterface.

  15. A mathematical model and simulation results of plasma enhanced chemical vapor deposition of silicon nitride films

    NASA Astrophysics Data System (ADS)

    Konakov, S. A.; Krzhizhanovskaya, V. V.

    2015-01-01

    We developed a mathematical model of Plasma Enhanced Chemical Vapor Deposition (PECVD) of silicon nitride thin films from SiH4-NH3-N2-Ar mixture, an important application in modern materials science. Our multiphysics model describes gas dynamics, chemical physics, plasma physics and electrodynamics. The PECVD technology is inherently multiscale, from macroscale processes in the chemical reactor to atomic-scale surface chemistry. Our macroscale model is based on Navier-Stokes equations for a transient laminar flow of a compressible chemically reacting gas mixture, together with the mass transfer and energy balance equations, Poisson equation for electric potential, electrons and ions balance equations. The chemical kinetics model includes 24 species and 58 reactions: 37 in the gas phase and 21 on the surface. A deposition model consists of three stages: adsorption to the surface, diffusion along the surface and embedding of products into the substrate. A new model has been validated on experimental results obtained with the "Plasmalab System 100" reactor. We present the mathematical model and simulation results investigating the influence of flow rate and source gas proportion on silicon nitride film growth rate and chemical composition.

  16. Enhancement of physical properties of indium tin oxide deposited by super density arc plasma ion plating by O 2 plasma treatment

    NASA Astrophysics Data System (ADS)

    Kim, Soo Young; Hong, Kihyon; Lee, Jong-Lam; Choi, Kyu Han; Song, Kyu Ho; Ahn, Kyung Chul

    2008-01-01

    Indium tin oxide (ITO) films were deposited on glass by super density arc plasma ion plating (SDAP-IP) method. In X-ray diffraction profiles, no obvious changes were found after O 2 plasma treatment. The transmittance, roughness, X-ray diffraction pattern, and sheet resistance also negligibly changed with O 2 plasma treatment. However, the water contact angle decreased with the O 2 plasma treatment, suggesting the increase of cohesive force between SDAP-IP ITO and organic materials. Synchrotron radiation photoemission spectroscopy showed that O 2 plasma treatment resulted in an increase of SDAP-IP ITO work function. Incorporation of oxygen atoms near the SDAP-IP ITO surface during the O 2 plasma treatment induced a peroxidic ITO surface, increasing the work function.

  17. Plasma-enhanced chemical vapor deposition of n-heptane and methyl methacrylate for potential cell alignment applications.

    PubMed

    Steinbach, Annina; Tautzenberger, Andrea; Schaller, Andreas; Kalytta-Mewes, Andreas; Tränkle, Sebastian; Ignatius, Anita; Volkmer, Dirk

    2012-10-24

    Plasma-enhanced chemical vapor deposited polymers (plasma polymers) are promising candidates for biomaterials applications. In the present study, plasma deposition as a fast and easily scalable method was adapted to deposit coatings from n-heptane and methyl methacrylate monomers onto glass substrates. Linear patterns with line and groove widths between 1.25 and 160 μm were introduced by degrative UV-lithography for cell alignment. Differential interference contrast optical microscopy, profilometry and atomic force microscopy revealed that the patterned surfaces had a smooth, homogeneous appearance and a pattern height of 8 and 45 nm for plasma deposited n-heptane and methyl methacrylate, respectively. UV-lithography increased the oxygen content on the surface drastically as shown by X-ray photoelectron spectroscopy. After immersion in simulated body fluid for 21 days, the pattern was still intact, and the ester groups were also maintained for the most part as shown by infrared spectroscopy. To test the coatings' potential applicability for biomaterial surfaces in a preliminary experiment, we cultured murine preosteoblastic MC3T3-E1 cells on these coatings. Light and electron microscopically, a normal spindle-shaped and aligned cell morphology was observed. At the mRNA level, cells showed no signs of diminished proliferation or elevated expression of apoptosis markers. In conclusion, plasma-enhanced chemical vapor deposited polymers can be patterned with a fast and feasible method and might be suitable materials to guide cell alignment.

  18. Effect of hydrogen addition on the deposition of titanium nitride thin films in nitrogen added argon magnetron plasma

    NASA Astrophysics Data System (ADS)

    Saikia, P.; Bhuyan, H.; Diaz-Droguett, D. E.; Guzman, F.; Mändl, S.; Saikia, B. K.; Favre, M.; Maze, J. R.; Wyndham, E.

    2016-06-01

    The properties and performance of thin films deposited by plasma assisted processes are closely related to their manufacturing techniques and processes. The objective of the current study is to investigate the modification of plasma parameters occurring during hydrogen addition in N2  +  Ar magnetron plasma used for titanium nitride thin film deposition, and to correlate the measured properties of the deposited thin film with the bulk plasma parameters of the magnetron discharge. From the Langmuir probe measurements, it was observed that the addition of hydrogen led to a decrease of electron density from 8.6 to 6.2  ×  (1014 m-3) and a corresponding increase of electron temperature from 6.30 to 6.74 eV. The optical emission spectroscopy study reveals that with addition of hydrogen, the density of argon ions decreases. The various positive ion species involving hydrogen are found to increase with increase of hydrogen partial pressure in the chamber. The thin films deposited were characterized using standard surface diagnostic tools such as x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), x-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Although it was possible to deposit thin films of titanium nitride with hydrogen addition in nitrogen added argon magnetron plasma, the quality of the thin films deteriorates with higher hydrogen partial pressures.

  19. Characterization and protein-adsorption behavior of deposited organic thin film onto titanium by plasma polymerization with hexamethyldisiloxane.

    PubMed

    Hayakawa, Tohru; Yoshinari, Masao; Nemoto, Kimiya

    2004-01-01

    Plasma polymerized hexamethyldisiloxane (HMDSO) thin film was deposited onto titanium using a radio-frequency apparatus for the surface modification of titanium. A titanium disk was first polished using colloidal silica at pH=9.8. Plasma-polymerized HMDSO films were firmly attached to the titanium by heating the titanium to a temperature of approximately 250 degrees C. The thickness of the deposited film was 0.07-0.35mum after 10-60min of plasma polymerization. The contact angle with respect to double distilled water significantly increased after HMDSO coating. X-ray photoelectron spectroscopy revealed that the deposited thin film consisted of Si, C, and O atoms. No Ti peaks were observed on the deposited surface. The deposited HMDSO film was stable during 2-weeks immersion in phosphate buffer saline solution. Fourier transform reflection-absorption spectroscopy showed the formation of Si-H, Si-C, C-H, and Cz.dbnd6;O bonds in addition to Si-O-Si bonds. Quartz crystal microbalance-dissipation measurement demonstrated that the deposition of HMDSO thin films on titanium has a benefit for fibronectin adsorption at the early stage. In conclusion, plasma polymerization is a promising technique for the surface modification of titanium. HMDSO-coated titanium has potential application as a dental implant material.

  20. Morphological and Electrochemical Study of Sulfide/Nitride Nanostructure Deposited Through Pulsed Plasma Electrolysis

    NASA Astrophysics Data System (ADS)

    Tavakoli, H.; Sobhani, M.

    2017-04-01

    This study investigated the feasibility of coating a steel St12 substrate with a sulfide/nitride layer. The coating process was conducted through a plasma electrolysis technique with a pulsed regime applied at frequencies of 100, 500, and 1000 Hz. It was found that the use of higher frequencies in the mentioned process provides better control over workpiece surface temperature and leads to reduced extent of voltage variations required to achieve a fixed temperature. The coating deposited at the frequency of 1000 Hz and voltage of about 235 V exhibited a nanostructure composed of 50 nm particles. The deposited coating consisted of an outer porous layer and an inner relatively dense layer. The x-ray studies identified the phases of the coating as γ'-Fe4N, Fe2-3N and FeS. The presence of FeS phase reduces the friction coefficient of the surface to about half the value obtainable in its absence. Studying the electrochemical impedance of the layer revealed that using a higher frequency in the deposition process increases the stability of resulting layer against seven days of immersion in the corrosive solution.

  1. Morphological and Electrochemical Study of Sulfide/Nitride Nanostructure Deposited Through Pulsed Plasma Electrolysis

    NASA Astrophysics Data System (ADS)

    Tavakoli, H.; Sobhani, M.

    2017-03-01

    This study investigated the feasibility of coating a steel St12 substrate with a sulfide/nitride layer. The coating process was conducted through a plasma electrolysis technique with a pulsed regime applied at frequencies of 100, 500, and 1000 Hz. It was found that the use of higher frequencies in the mentioned process provides better control over workpiece surface temperature and leads to reduced extent of voltage variations required to achieve a fixed temperature. The coating deposited at the frequency of 1000 Hz and voltage of about 235 V exhibited a nanostructure composed of 50 nm particles. The deposited coating consisted of an outer porous layer and an inner relatively dense layer. The x-ray studies identified the phases of the coating as γ'-Fe4N, Fe2-3N and FeS. The presence of FeS phase reduces the friction coefficient of the surface to about half the value obtainable in its absence. Studying the electrochemical impedance of the layer revealed that using a higher frequency in the deposition process increases the stability of resulting layer against seven days of immersion in the corrosive solution.

  2. Functional metal oxide coatings by molecule-based thermal and plasma chemical vapor deposition techniques.

    PubMed

    Mathur, S; Ruegamer, T; Donia, N; Shen, H

    2008-05-01

    Deposition of thin films through vaccum processes plays an important role in industrial processing of decorative and functional coatings. Many metal oxides have been prepared as thin films using different techniques, however obtaining compositionally uniform phases with a control over grain size and distribution remains an enduring challenge. The difficulties are largely related to complex compositions of functional oxide materials, which makes a control over kinetics of nucleation and growth processes rather difficult to control thus resulting in non-uniform material and inhomogeneous grain size distribution. Application of tailor-made molecular precursors in low pressure or plasma-enhanced chemical vapor deposition (CVD) techniques offers a viable solution for overcoming thermodynamic impediments involved in thin film growth. In this paper molecule-based CVD of functional coatings is demonstrated for iron oxide (Fe2O3, Fe3O4), vanadium oxide (V2O5, VO2) and hafnium oxide (HfO2) phases followed by the characterization of their microstructural, compositional and functional properties which support the advantages of chemical design in simplifying deposition processes and optimizing functional behavior.

  3. Wettability of modified silica layers deposited on glass support activated by plasma

    NASA Astrophysics Data System (ADS)

    Terpiłowski, Konrad; Rymuszka, Diana; Goncharuk, Olena V.; Sulym, Iryna Ya.; Gun'ko, Vladimir M.

    2015-10-01

    Fumed silica modified by hexamethyldisilazane [HDMS] and polydimethylsiloxane [PDMS] was dispersed in a polystyrene/chloroform solution. To increase adhesion between deposited silica layers and a glass surface, the latter was pretreated with air plasma for 30 s. The silica/polystyrene dispersion was deposited on the glass support using a spin coater. After deposition, the plates were dried in a desiccator for 24 h. Water advancing and receding contact angles were measured using the tilted plate method. The apparent surface free energy (γS) was evaluated using the contact angle hysteresis approach. The surface topography was determined using the optical profilometry method. Contact angles changed from 59.7° ± 4.4 (at surface coverage with trimethylsilyl groups Θ = 0.14) to 155° ± 3.1 at Θ = 1. The value of γS decreased from 51.3 ± 2.8 mJ/m2 (for the sample at the lowest value of Θ) to 1.0 ± 0.4 mJ/m2 for the most hydrophobic sample. Thus, some systems with a high degree of modification by HDMS showed superhydrophobicity, and the sliding angle amounted to about 16° ± 2.1.

  4. Uniform GaN thin films grown on (100) silicon by remote plasma atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Shih, Huan-Yu; Lin, Ming-Chih; Chen, Liang-Yih; Chen, Miin-Jang

    2015-01-01

    The growth of uniform gallium nitride (GaN) thin films was reported on (100) Si substrate by remote plasma atomic layer deposition (RP-ALD) using triethylgallium (TEG) and NH3 as the precursors. The self-limiting growth of GaN was manifested by the saturation of the deposition rate with the doses of TEG and NH3. The increase in the growth temperature leads to the rise of nitrogen content and improved crystallinity of GaN thin films, from amorphous at a low deposition temperature of 200 °C to polycrystalline hexagonal structures at a high growth temperature of 500 °C. No melting-back etching was observed at the GaN/Si interface. The excellent uniformity and almost atomic flat surface of the GaN thin films also infer the surface control mode of the GaN thin films grown by the RP-ALD technique. The GaN thin films grown by RP-ALD will be further applied in the light-emitting diodes and high electron mobility transistors on (100) Si substrate.

  5. Preparation Of Electrochromic Metal Oxide Films By Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Benson, D. K.; Tracy, C. E.; Svensson, J. S. E. M.; Liebert, B. E.

    1987-11-01

    Laboratory procedures have been developed for depositing thin films of electrochromic metal oxides by plasma-enhanced chemical vapor deposition (PE-CVD). In this process, vapor phase reactants, such as tungsten hexafluotIde, are mixed with oxygen and excited by RF energy at a frequency of 13.56 MHz and power levels up to≍1W/cm2 substrate area. Large rates of oxide deposition have been achieved (> 8 nm/s) making this process a candidate for high-speed coating of large area substrates, such as window glass. Amorphous WO1 films prepared by PE-CVD have been shown to have electrochromic responses virtually identical to films prepared by vacuum evaporation. The lithium ion diffusion rate, for example, is approximately 1.3 x 10-11 cm2 /s at x = 0.03 in LixWO3 prepared by PE-CVD. On the other hand, molybdenum oxide films and mixed molybdenum/tungsten oxide films prepared by PE-CVD from the hexafluorides differ markedly from vacuum evaporated films. Their electrochromic responses are spectrally different and are much slower. Lithium ion diffusion rates in such Mo03 films are lower by about three orders of magnitude. These differences are tentatively attributed to a large fraction of fluorine (Mo:F ratios of the order of 2:1) which are incorporated into the molybdenum and mixed oxides, but are not incorporated into the tungsten oxides.

  6. Wetting behaviour of carbon nitride nanostructures grown by plasma enhanced chemical vapour deposition technique

    NASA Astrophysics Data System (ADS)

    Ahmad Kamal, Shafarina Azlinda; Ritikos, Richard; Abdul Rahman, Saadah

    2015-02-01

    Tuning the wettability of various coating materials by simply controlling the deposition parameters is essential for various specific applications. In this work, carbon nitride (CNx) films were deposited on silicon (1 1 1) substrates using radio-frequency plasma enhanced chemical vapour deposition employing parallel plate electrode configuration. Effects of varying the electrode distance (DE) on the films' structure and bonding properties were investigated using Field emission scanning electron microscopy, Atomic force microscopy, Fourier transform infrared and X-ray photoemission spectroscopy. The wettability of the films was analyzed using water contact angle measurements. At high DE, the CNx films' surface was smooth and uniform. This changed into fibrous nanostructures when DE was decreased. Surface roughness of the films increased with this morphological transformation. Nitrogen incorporation increased with decrease in DE which manifested the increase in both relative intensities of Cdbnd N to Cdbnd C and Nsbnd H to Osbnd H bonds. sp2-C to sp3-C ratio increased as DE decreased due to greater deformation of sp2 bonded carbon at lower DE. The films' characteristics changed from hydrophilic to super-hydrophobic with the decrease in DE. Roughness ratio, surface porosity and surface energy calculated from contact angle measurements were strongly dependent on the morphology, surface roughness and bonding properties of the films.

  7. Current transport mechanisms in plasma-enhanced atomic layer deposited AlN thin films

    SciTech Connect

    Altuntas, Halit E-mail: biyikli@unam.bilkent.edu.tr; Ozgit-Akgun, Cagla; Donmez, Inci; Biyikli, Necmi E-mail: biyikli@unam.bilkent.edu.tr

    2015-04-21

    Here, we report on the current transport mechanisms in AlN thin films deposited at a low temperature (i.e., 200 °C) on p-type Si substrates by plasma-enhanced atomic layer deposition. Structural characterization of the deposited AlN was carried out using grazing-incidence X-ray diffraction, revealing polycrystalline films with a wurtzite (hexagonal) structure. Al/AlN/ p-Si metal-insulator-semiconductor (MIS) capacitor structures were fabricated and investigated under negative bias by performing current-voltage measurements. As a function of the applied electric field, different types of current transport mechanisms were observed; i.e., ohmic conduction (15.2–21.5 MV/m), Schottky emission (23.6–39.5 MV/m), Frenkel-Poole emission (63.8–211.8 MV/m), trap-assisted tunneling (226–280 MV/m), and Fowler-Nordheim tunneling (290–447 MV/m). Electrical properties of the insulating AlN layer and the fabricated Al/AlN/p-Si MIS capacitor structure such as dielectric constant, flat-band voltage, effective charge density, and threshold voltage were also determined from the capacitance-voltage measurements.

  8. Surface modification of silicon-containing fluorocarbon films prepared by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Jin, Yoonyoung; Desta, Yohannes; Goettert, Jost; Lee, G. S.; Ajmera, P. K.

    2005-07-01

    Surface modification of silicon-containing fluorocarbon (SiCF) films achieved by wet chemical treatments and through x-ray irradiation is examined. The SiCF films were prepared by plasma-enhanced chemical vapor deposition, using gas precursors of tetrafluoromethane and disilane. As-deposited SiCF film composition was analyzed by x-ray photoelectron spectroscopy. Surface modification of SiCF films utilizing n-lithiodiaminoethane wet chemical treatment is discussed. Sessile water-drop contact angle changed from 95°+/-2° before treatment to 32°+/-2° after treatment, indicating a change in the film surface characteristics from hydrophobic to hydrophilic. For x-ray irradiation on the SiCF film with a dose of 27.4 kJ/cm3, the contact angle of the sessile water drop changed from 95°+/-2° before radiation to 39°+/-3° after x-ray exposure. The effect of x-ray exposure on chemical bond structure of SiCF films is studied using Fourier transform infrared measurements. Electroless Cu deposition was performed to test the applicability of the surface modified films. The x-ray irradiation method offers a unique advantage in making possible surface modification in a localized area of high-aspect-ratio microstructures. Fabrication of a Ti-membrane x-ray mask is introduced here for selective surface modification using x-ray irradiation.

  9. Surface Modification of Conventional Polymers by Depositing Plasma Polymers of Trimethylsilane and of Trimethylsilane + O2.

    PubMed

    Weikart; Miyama; Yasuda

    1999-03-01

    The static wetting properties of TMS (trimethylsilane) and TMS + O2 plasma deposited films on eleven low energy conventional polymers were investigated using the sessile droplet method. The static advancing contact angle is an excellent indication of the change in surface state properties from plasma surface modification. However, traditional contact angle measuring techniques possess a methodological limitation, which can leave a water droplet on the substrate surface for up to 3 min before a measurement is obtained. The static "advancing" contact angles of different size water droplets on teflon and nylon surfaces were observed to change significantly in 2 min while equilibrating with the surface and surroundings. A new quick image-capturing device enables static contact angle measurement 2 to 4 s after contact with the substrate. This technique virtually eliminates the time dependent effects of evaporation and surface state change, which are believed to be responsible for the change in static advancing contact angles. Furthermore, static contact angles independent of droplet volume and contact time may be taken as a surface characteristic property, which is denoted as the intrinsic static contact angle, θS. The static "advancing" contact angle, measured in this fashion, indicated that the wetting properties of TMS and TMS + O2 plasma polymer deposition on 10 conventional polymers were modified virtually independent of the underlying substrate. The average advancing contact angles on TMS and TMS + O2 modified polymers are θS = 94 +/- 2.2 (cos θS = -0.0645) and θS = 32 +/- 6.9 (cos θS = 0.8452), respectively. Copyright 1999 Academic Press.

  10. Organo-Chlorinated Thin Films Deposited by Atmospheric Pressure Plasma-Enhanced Chemical Vapor Deposition for Adhesion Enhancement between Rubber and Zinc-Plated Steel Monofilaments.

    PubMed

    Vandenabeele, Cédric; Bulou, Simon; Maurau, Rémy; Siffer, Frederic; Belmonte, Thierry; Choquet, Patrick

    2015-07-08

    A continuous-flow plasma process working at atmospheric pressure is developed to enhance the adhesion between a rubber compound and a zinc-plated steel monofilament, with the long-term objective to find a potential alternative to the electrolytic brass plating process, which is currently used in tire industry. For this purpose, a highly efficient tubular dielectric barrier discharge reactor is built to allow the continuous treatment of "endless" cylindrical substrates. The best treatment conditions found regarding adhesion are Ar/O2 plasma pretreatment, followed by the deposition from dichloromethane of a 75 nm-thick organo-chlorinated plasma polymerized thin film. Ar/O2 pretreatment allows the removal of organic residues, coming from drawing lubricants, and induces external growth of zinc oxide. The plasma layer has to be preferably deposited at low power to conserve sufficient hydrocarbon moieties. Surface analyses reveal the complex chemical mechanism behind the establishment of strong adhesion levels, more than five times higher after the plasma treatment. During the vulcanization step, superficial ZnO reacts with the chlorinated species of the thin film and is converted into porous and granular bump-shaped ZnwOxHyClz nanostructures. Together, rubber additives diffuse through the plasma layer and lead to the formation of zinc sulfide on the substrate surface. Hence, two distinct interfaces, rubber/thin film and thin film/substrate, are established. On the basis of these observations, hypotheses explaining the high bonding strength results are formulated.

  11. Novel thin films deposited on electrospun PCL scaffolds by atmospheric pressure plasma jet for L929 fibroblast cell cultivation

    NASA Astrophysics Data System (ADS)

    Gozutok, M.; Baitukha, A.; Arefi-Khonsari, F.; Turkoglu Sasmazel, H.

    2016-11-01

    This paper reports on the deposition of PCL homopolymers and poly ɛ-caprolactone-polyethylene glycol (PCL-PEG) copolymers by atmospheric pressure plasma jet (APPJ) onto electrospun PCL scaffolds for improving L929 fibroblast cell growth. Polymer deposited scaffolds showed better stability as well as lower CA as compared to those treated with APPJ in Ar alone used as the carrier gas to introduce the precursors due to the formation of polar groups generated during the plasma treatment, such as -OH and/or -COO. Average fiber and porosity sizes were calculated by using SEM photographs and the ImageJ Launcher Software program and higher values were observed for both PCL and PCL-PEG deposited scaffolds than the untreated electrospun PCL scaffolds. XPS analysis showed that C1s% content decreased for PCL deposited (from 82.4% to 71.0%) and PCL-PEG deposited (from 82.4% to 57.7%) and O1s% composition increased for PCL deposited (from 17.6% to 29.0%) and PCL-PEG deposited (from 17.6% to 42.3%) compared to the untreated one. XPS results proved more incorporation of oxygen moieties on the deposited surfaces than the untreated samples giving rise to more hydrophilic surfaces to the deposited ones. Standard in vitro MTT test, Giemsa staining, fluorescence and CLSM imaging techniques were used for the determination of cell viability, adhesion and proliferation. Cell culture experiments showed that PCL-PEG deposited electrospun PCL scaffolds had the most promising cell adhesion, proliferation and growth among the treated scaffolds. The increased average fiber diameter caused by deposition as well as oxygen containing polar groups formed on the surfaces due to the radicals present in the plasma atmosphere provided higher surface area and functionality, respectively, for cells to attach, yielding better biocompatibility performance.

  12. Redeposition in plasma-assisted atomic layer deposition: Silicon nitride film quality ruled by the gas residence time

    NASA Astrophysics Data System (ADS)

    Knoops, Harm C. M.; de Peuter, K.; Kessels, W. M. M.

    2015-07-01

    The requirements on the material properties and growth control of silicon nitride (SiNx) spacer films in transistors are becoming ever more stringent as scaling of transistor structures continues. One method to deposit high-quality films with excellent control is atomic layer deposition (ALD). However, depositing SiNx by ALD has turned out to be very challenging. In this work, it is shown that the plasma gas residence time τ is a key parameter for the deposition of SiNx by plasma-assisted ALD and that this parameter can be linked to a so-called "redeposition effect". This previously ignored effect, which takes place during the plasma step, is the dissociation of reaction products in the plasma and the subsequent redeposition of reaction-product fragments on the surface. For SiNx ALD using SiH2(NHtBu)2 as precursor and N2 plasma as reactant, the gas residence time τ was found to determine both SiNx film quality and the resulting growth per cycle. It is shown that redeposition can be minimized by using a short residence time resulting in high-quality films with a high wet-etch resistance (i.e., a wet-etch rate of 0.5 nm/min in buffered HF solution). Due to the fundamental nature of the redeposition effect, it is expected to play a role in many more plasma-assisted ALD processes.

  13. Effect of process parameters on the mechanical properties of carbon nitride thin films synthesized by plasma assisted pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Tabbal, M.; Mérel, P.; Chaker, M.

    We present an investigation of the effect of the process parameters, namely deposition pressure and laser intensity, on the growth and mechanical properties of carbon nitride (CNx) thin films synthesized by plasma assisted pulsed laser deposition. Deposition at high remote plasma pressure (200 mTorr) enhances both growth rate and nitrogen incorporation (up to 40 at.%), but nano-indentation measurements indicate that these films are very soft and have poor mechanical properties. At low remote plasma pressure (0.5 mTorr), the nitrogen content varies from 24 to 16 at.% with increasing laser intensity as the films become much harder and more elastic, with hardness and Young's modulus values reaching 24 GPa and 230 GPa, respectively. These effects are explained in terms of a thermalization of the laser plasma at 200 mTorr and indicate that plasma activation of nitrogen does not provide any particular benefit to the film properties when deposition is performed at high pressure. However, at low pressure, the benefit of plasma activation is evidenced through enhanced nitrogen incorporation in the films while preserving the highly energetic species in the ablation plume. Such conditions lead to the synthesis, at room temperature, of hard and elastic films having properties close to those of fullerene-like CNx.

  14. Low-temperature plasma-deposited silicon epitaxial films: Growth and properties

    DOE PAGES

    Demaurex, Bénédicte; Bartlome, Richard; Seif, Johannes P.; ...

    2014-08-05

    Low-temperature (≤ 180 °C) epitaxial growth yields precise thickness, doping, and thermal-budget control, which enables advanced-design semiconductor devices. In this paper, we use plasma-ehanced chemical vapor deposition to grow homo-epitaxial layers and study the different growth modes on crystalline silicon substrates. In particular, we determine the conditions leading to epitaxial growth in light of a model that depends only on the silane concentration in the plasma and the mean free path length of surface adatoms. For such growth, we show that the presence of a persistent defective interface layer between the crystalline silicon substrate and the epitaxial layer stems notmore » only from the growth conditions but also from unintentional contamination of the reactor. As a result of our findings, we determine the plasma conditions to grow high-quality bulk epitaxial films and propose a two-step growth process to obtain device-grade material.« less

  15. Vacuum arc plasma generation and thin film deposition from a TiB{sub 2} cathode

    SciTech Connect

    Zhirkov, Igor Petruhins, Andrejs; Naslund, Lars-Ake; Rosen, Johanna; Kolozsvári, Szilard; Polcik, Peter

    2015-11-02

    We have studied the utilization of TiB{sub 2} cathodes for thin film deposition in a DC vacuum arc system. We present a route for attaining a stable, reproducible, and fully ionized plasma flux of Ti and B by removal of the external magnetic field, which leads to dissipation of the vacuum arc discharge and an increased active surface area of the cathode. Applying a magnetic field resulted in instability and cracking, consistent with the previous reports. Plasma analysis shows average energies of 115 and 26 eV, average ion charge states of 2.1 and 1.1 for Ti and B, respectively, and a plasma ion composition of approximately 50% Ti and 50% B. This is consistent with measured resulting film composition from X-ray photoelectron spectroscopy, suggesting a negligible contribution of neutrals and macroparticles to the film growth. Also, despite the observations of macroparticle generation, the film surface is very smooth. These results are of importance for the utilization of cathodic arc as a method for synthesis of metal borides.

  16. Plasma restructuring of catalysts for chemical vapor deposition of carbon nanotubes

    SciTech Connect

    Cantoro, M.; Hofmann, S.; Pisana, S.; Parvez, A.; Fasoli, A.; Scardaci, V.; Ferrari, A. C.; Robertson, J.; Mattevi, C.; Ducati, C.

    2009-03-15

    The growth of multiwalled carbon nanotubes and carbon nanofibers by catalytic chemical vapor deposition at lower temperatures is found to be aided by a separate catalyst pretreatment step in which the catalyst thin film is restructured into a series of nanoparticles with a more active surface. The restructuring is particularly effective when carried out by an ammonia plasma. The nature of the restructuring is studied by atomic force microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and Raman. We find that as the growth temperature decreases, there is a limiting maximum catalyst thickness, which gives any nanotube growth. Plasmas are found to restructure the catalyst by a combination of physical etching and chemical modification. Large plasma powers can lead to complete etching of thin catalyst films, and hence loss of activity. Ni is found to be the better catalyst at low temperatures because it easily reduced from any oxide form to the catalytically active metallic state. On the other hand, Fe gives the largest nanotube length and density yield at moderate temperatures because it is less easy to reduce at low temperatures and it is more easily poisoned at high temperatures.

  17. Structure of the metallic films deposited on small spheres trapped in the rf magnetron plasma

    NASA Astrophysics Data System (ADS)

    Filippov, A. V.; Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.

    2016-11-01

    Metallic coatings were deposited onto glass spheres having diameters from several to one hundred micrometers by the magnetron sputtering. Two different experimental schemes were exploited. One of them had the traditional configuration where a magnetron sputter was placed at one hundred millimeters from particles. In this scheme, continuous mechanical agitation in a fluidized bed was used to achieve uniformity of coatings. In the second scheme the treated particles (substrates) levitated in a magnetron rf plasma over a sputtered rf electrode (target) at the distance d of few mm from it and at gas pressure p values of 30-100 mTorr. These parameters are essentially different from those in the traditional sputtering. Agitation due to the features of a particle confinement in dusty plasma was used here to obtain uniform coatings. Thickness and morphology of the obtained coatings were studied. As it is known, film growth rate and structure are determined by the substrate temperature, the densities of ion and neutral atom fluxes to the substrate surface, the radiation flux density, and the heat energy produced due to the surface condensation of atoms and recombination of electrons and ions. These parameters particularly depend on the product of p and d. In the case of magnetron rf dusty plasma, it is possible to achieve the pd value several times lower than the lowest value proper to the first traditional case. Completely different dependencies of the film growth rate and structure on the pd value in these sputtering processes were observed and qualitatively explained.

  18. Supported plasma sputtering apparatus for high deposition rate over large area

    DOEpatents

    Moss, Ronald W.; McClanahan, Jr., Edwin D.; Laegreid, Nils

    1977-01-01

    A supported plasma sputtering apparatus is described having shaped electrical fields in the electron discharge region between the cathode and anode and the sputter region between the target and substrate while such regions are free of any externally applied magnetic field to provide a high deposition rate which is substantially uniform over a wide area. Plasma shaping electrodes separate from the anode and target shape the electrical fields in the electron discharge region and the sputter region to provide a high density plasma. The anode surrounds the target to cause substantially uniform sputtering over a large target area. In one embodiment the anode is in the form of an annular ring surrounding a flat target surface, such anode being provided with a ribbed upper surface which shields portions of the anode from exposure to sputtered material to maintain the electron discharge for a long stable operation. Several other embodiments accomplish the same result by using different anodes which either shield the anode from sputtered material, remove the sputtered coating on the anode by heating, or simultaneously mix sputtered metal from the auxiliary target with sputtered insulator from the main target so the resultant coating is conductive. A radio frequency potential alone or together with a D.C. potential, may be applied to the target for a greater sputtering rate.

  19. Room temperature radio-frequency plasma-enhanced pulsed laser deposition of ZnO thin films

    NASA Astrophysics Data System (ADS)

    Huang, S.-H.; Chou, Y.-C.; Chou, C.-M.; Hsiao, V. K. S.

    2013-02-01

    In this study, we compared the crystalline structures, optical properties, and surface morphologies of ZnO thin films deposited on silicon and glass substrates by conventional pulsed laser deposition (PLD) and radio-frequency (RF) plasma-enhanced PLD (RF-PEPLD). The depositions were performed at room temperature under 30-100 mTorr pressure conditions. The RF-PEPLD process was found to have deposited a ZnO structure with preferred (0 0 2) c-axis orientation at a higher deposition rate; however, the RF-PEPLD process generated more defects in the thin films. The application of oxygen pressure to the RF-PEPLD process reduced defects effectively and also increased the deposition rate.

  20. Growth of γ-alumina thin films by pulsed laser deposition and plasma diagnostic

    NASA Astrophysics Data System (ADS)

    Yahiaoui, K.; Abdelli-Messaci, S.; Messaoud Aberkane, S.; Siad, M.; Kellou, A.

    2017-07-01

    The present work discusses about the synthesis of alumina thin films, which have applications in current and next-generation solid-state electronic devices due to their attractive properties. Alumina thin films were synthesized by pulsed laser deposition at different oxygen pressures and substrate temperatures. The dependence of substrate temperature, oxygen pressure, and the deposition time on the properties of the films has been observed by growing three series of alumina thin films on Si (100). The first films are synthesized using substrate temperatures ranging from room temperature to 780 °C at 0.01 mbar of O2. The second series was realized at a fixed substrate temperature of 760 °C and varied oxygen pressure (from 0.005 to 0.05 mbar). The third set of series was elaborated at different deposition times (from 15 to 60 min) while the oxygen pressure and the substrate temperature were fixed at 0.01 mbar and 760 °C, respectively. The films were characterized using X-ray diffractometer (XRD) for structural analysis, a scanning electron microscope for morphological analysis, a nano-indenter for mechanical analysis (hardness and Young's modulus), and Rutherford backscattering spectroscopy for thickness and stoichiometry measurements. Using optical emission spectroscopy, plasma diagnostic was carried out both in the vacuum and in the presence of oxygen with a pressure ranging from 0.01 to 0.05 mbar. Several neutral, ionic, and molecular species were identified such as Al, Al+, and Al++ in vacuum and in oxygen ambiance, O and AlO molecular bands in oxygen-ambient atmosphere. The spatiotemporal evolution of the most relevant species was achieved and their velocities were estimated. The highest amount of crystallized alumina in γ-phase was found in the films elaborated under 0.01 mbar of O2, at a substrate temperature of 780 °C, and a deposition time of 60 min.

  1. Silicon oxide barrier films deposited on PET foils in pulsed plasmas: influence of substrate bias on deposition process and film properties

    NASA Astrophysics Data System (ADS)

    Steves, S.; Ozkaya, B.; Liu, C.-N.; Ozcan, O.; Bibinov, N.; Grundmeier, G.; Awakowicz, P.

    2013-02-01

    A widely used plastic for packaging, polyethylene terephtalate (PET) offers limited barrier properties against gas permeation. For many applications of PET (from food packaging to micro electronics) improved barrier properties are essential. A silicon oxide barrier coating of PET foils is applied by means of a pulsed microwave driven low-pressure plasma. While the adjustment of the microwave power allows for a control of the ion production during the plasma pulse, a substrate bias controls the energy of ions impinging on the substrate. Detailed analysis of deposited films applying oxygen permeation measurements, x-ray photoelectron spectroscopy and atomic force microscopy are correlated with results from plasma diagnostics describing the deposition process. The influence of a change in process parameters such as gas mixture and substrate bias on the gas temperature, electron density, mean electron energy, ion energy and the atomic oxygen density is studied. An additional substrate bias results in an increase in atomic oxygen density up to a factor of 6, although plasma parameter such as electron density of ne = 3.8 ± 0.8 × 1017 m-3 and electron temperature of kBTe = 1.7 ± 0.1 eV are unmodified. It is shown that atomic oxygen densities measured during deposition process higher than nO = 1.8 × 1021 m-3 yield in barrier films with a barrier improvement factor up to 150. Good barrier films are highly cross-linked and show a smooth morphology.

  2. Deposition and properties of high-velocity-oxygen-fuel and plasma-sprayed Mo-Mo2C composite coatings

    NASA Astrophysics Data System (ADS)

    Prchlik, L.; Gutleber, J.; Sampath, S.

    2001-12-01

    Molybdenum thermal-spray coatings, dispersion strengthened by molybdenum oxides and molybdenum carbides, play an important role in industrial tribological applications. Traditionally, they have been prepared by plasma and wire flame spraying. High porosity and lower cohesion strength limit their application in situations where both galling and abrasion wear is involved. In this study, high-velocity-oxygen-fuel (HVOF) deposition of molybdenum and molybdenum carbide coatings was attempted. Deposition was achieved for all powders used. Composition, microstructure, mechanical, and wear properties of the HVOF synthesized coatings were evaluated and compared with plasma-sprayed counterparts. The HVOF coatings possessed a very good abrasion resistance, whereas plasma deposits performed better in dry sliding tests. Measurements showed a close relationship between the coating surface hardness and its abrasion resistance. Results also suggested correlation between molybdenum carbide distribution in the molybdenum matrix and the sliding friction response of Mo-Mo2C coatings.

  3. Chemical vapour deposition enhanced by atmospheric microwave plasmas: a large-scale industrial process or the next nanomanufacturing tool?

    NASA Astrophysics Data System (ADS)

    Belmonte, T.; Gries, T.; Cardoso, R. P.; Arnoult, G.; Kosior, F.; Henrion, G.

    2011-04-01

    This paper describes several specific aspects of atmospheric plasma deposition carried out with a microwave resonant cavity. Deposition over a wide substrate is first studied. We show that high deposition rates (several hundreds of μm h-1) are due to localization of fluxes on the substrate by convection when slightly turbulent flows are used. Next, we describe possible routes to localize deposition over a nanometre-sized area. Scaling down atmospheric plasma deposition is possible and two strategies to reach nanometre scales are described. Finally, we study self-organization of SiO2 nanodots deposited by chemical vapour deposition at atmospheric pressure enhanced by an Ar-O2 micro-afterglow operating at high temperature (>1200 K). When the film being deposited is thin enough (~500 nm) nanodots are obtained and they can be assembled into threads to create patterned surfaces. When the coating becomes thicker (~1 µm), and for relatively high content in HMDSO, SiO2 walls forming hexagonal cells are obtained.

  4. Studies of lithium deposition and D retention on tungsten samples exposed to Li-seeded plasmas in PISCES-A

    NASA Astrophysics Data System (ADS)

    Tabarés, F. L.; Alegre, D.; Baldwin, M.; Nishijima, D.; Simmonds, M.; Doerner, R.; Alves, E.; Mateus, R.

    2017-04-01

    The interaction between lithium-seeded deuterium plasmas and tungsten targets has been studied in the PISCES-A divertor plasma simulator. Tungsten samples, of ITER-grade, with a diameter of 25 and 2 mm thick, were held at temperatures ranging from 403 to 873 K and exposed to Li/D plasmas under different plasma conditions and fixed total fluences of 5 ×1025 m‑2, with typical particle flux values of (1–5) × 1022 m‑2 s‑1. The deuterium and lithium contents of the samples after irradiation were analyzed by thermal desorption spectroscopy and nuclear reaction analysis (NRA). No lithium deposition was found within the sensitivity range of NRA, except for the cold (403 K) sample on which a layer with Li atomic density below 2 × 1022 m‑2 was detected. Deuterium retention values in the range of 1018 m‑2 were measured, even for the Li deposition conditions.

  5. Structural characterization of the interface structure of amorphous silicon thin films after post-deposition argon or hydrogen plasma treatment

    NASA Astrophysics Data System (ADS)

    Neumüller, Alex; Sergeev, Oleg; Vehse, Martin; Agert, Carsten

    2017-05-01

    The interfaces in silicon thin film solar cells and silicon heterojunction solar cells are considered to be very important for the solar cell conversion efficiency. This work studies the interface properties of hydrogenated amorphous silicon thin films deposited on crystalline silicon wafers after post-deposition hydrogen plasma treatment (HPT) or argon plasma treatment (APT). The investigation extends our previous study by examining the structural changes resulting from the post-deposition plasma treatment on silicon thin film solar cells. We analyzed the ellipsometry and infrared spectra of our samples to gain a deeper understanding of the fundamental plasma treatment effects. By using post-deposition APT and HPT, we were able to reduce the material stress and improve the structure of these layers. Our results show that APT yields a more compact material with fewer voids and less distinct localized tail states. We discuss the effect of APT and HPT on the most crucial interface in silicon heterojunction solar cells, the i-a-Si:H/c-Si interface. We propose to introduce APT as a post-deposition process step in the fabrication of silicon heterojunction solar cells.

  6. Structural and mechanical properties of Al-C-N films deposited at room temperature by plasma focus device

    NASA Astrophysics Data System (ADS)

    Z, A. Umar; R, Ahmad; R, S. Rawat; M, A. Baig; J, Siddiqui; T, Hussain

    2016-07-01

    The Al-C-N films are deposited on Si substrates by using a dense plasma focus (DPF) device with aluminum fitted central electrode (anode) and by operating the device with CH4/N2 gas admixture ratio of 1:1. XRD results verify the crystalline AlN (111) and Al3CON (110) phase formation of the films deposited using multiple shots. The elemental compositions as well as chemical states of the deposited Al-C-N films are studied using XPS analysis, which affirm Al-N, C-C, and C-N bonding. The FESEM analysis reveals that the deposited films are composed of nanoparticles and nanoparticle agglomerates. The size of the agglomerates increases at a higher number of focus deposition shots for multiple shot depositions. Nanoindentation results reveal the variation in mechanical properties (nanohardness and elastic modulus) of Al-C-N films deposited with multiple shots. The highest values of nanohardness and elastic modulus are found to be about 11 and 185 GPa, respectively, for the film deposited with 30 focus deposition shots. The mechanical properties of the films deposited using multiple shots are related to the Al content and C-N bonding.

  7. In Situ Nanocalorimetric Investigations of Plasma Assisted Deposited Poly(ethylene oxide)-like Films by Specific Heat Spectroscopy.

    PubMed

    Madkou, Sherif; Melnichu, Iurii; Choukourov, Andrei; Krakovsky, Ivan; Biederman, Hynek; Schönhals, Andreas

    2016-04-28

    In recent years, highly cross-linked plasma polymers have started to unveil their potential in numerous biomedical applications in thin-film form. However, conventional diagnostic methods often fail due to their diverse molecular dynamics conformations. Here, glassy dynamics and the melting transition of thin PEO-like plasma assisted deposited (ppPEO) films (thickness 100 nm) were in situ studied by a combination of specific heat spectroscopy, utilizing a pJ/K sensitive ac-calorimeter chip, and composition analytical techniques. Different cross-linking densities were obtained by different plasma powers during the deposition of the films. Glassy dynamics were observed for all values of the plasma power. It was found that the glassy dynamics slows down with increasing the plasma power. Moreover, the underlying relaxation time spectra broaden indicating that the molecular motions become more heterogeneous with increasing plasma power. In a second set of the experiment, the melting behavior of the ppPEO films was studied. The melting temperature of ppPEO was found to decrease with increasing plasma power. This was explained by a decrease of the order in the crystals due to formation of chemical defects during the plasma process.

  8. Plasma-Enhanced Pulsed Laser Deposition of Wide Bandgap Nitrides for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Triplett, G. E., Jr.; Durbin, S. M.

    2004-01-01

    The need for a reliable, inexpensive technology for small-scale space power applications where photovoltaic or chemical battery approaches are not feasible has prompted renewed interest in radioisotope-based energy conversion devices. Although a number of devices have been developed using a variety of semiconductors, the single most limiting factor remains the overall lifetime of the radioisotope battery. Recent advances in growth techniques for ultra-wide bandgap III-nitride semiconductors provide the means to explore a new group of materials with the promise of significant radiation resistance. Additional benefits resulting from the use of ultra-wide bandgap materials include a reduction in leakage current and higher operating voltage without a loss of energy transfer efficiency. This paper describes the development of a novel plasma-enhanced pulsed laser deposition system for the growth of cubic boron nitride semiconducting thin films, which will be used to construct pn junction devices for alphavoltaic applications.

  9. Stress hysteresis and mechanical properties of plasma-enhanced chemical vapor deposited dielectric films

    NASA Astrophysics Data System (ADS)

    Thurn, Jeremy; Cook, Robert F.; Kamarajugadda, Mallika; Bozeman, Steven P.; Stearns, Laura C.

    2004-02-01

    A comprehensive survey is described of the responses of three plasma-enhanced chemical vapor deposited dielectric film systems to thermal cycling and indentation contact. All three films—silicon oxide, silicon nitride, and silicon oxy-nitride—exhibited significant nonequilibrium permanent changes in film stress on thermal cycling or annealing. The linear relationship between stress and temperature changed after the films were annealed at 300 °C, representing a structural alteration in the film reflecting a change in coefficient of thermal expansion or biaxial modulus. A double-substrate method was used to deduce both thermoelastic properties before and after the anneal of selected films and the results were compared with the modulus deconvoluted from small-scale depth-sensing indentation experiments (nanoindentation). Rutherford backscattering spectrometry and hydrogen forward scattering were used to deduce the composition of the films and it was found that all the films contained significant amounts of hydrogen.

  10. Antifouling Transparent ZnO Thin Films Fabricated by Atmospheric Pressure Cold Plasma Deposition

    NASA Astrophysics Data System (ADS)

    Suzaki, Yoshifumi; Du, Jinlong; Yuji, Toshifumi; Miyagawa, Hayato; Ogawa, Kazufumi

    2015-09-01

    One problem with outdoor-mounted solar panels is that power generation efficiency is reduced by face plate dirt; a problem with electronic touch panels is the deterioration of screen visibility caused by finger grease stains. To solve these problems, we should fabricate antifouling surfaces which have superhydrophobic and oil-repellent properties without spoiling the transparency of the transparent substrate. In this study, an antifouling surface with both superhydrophobicity and oil-repellency was fabricated on a glass substrate by forming a fractal microstructure. The fractal microstructure was constituted of transparent silica particles 100 nm in diameter and transparent zinc-oxide columns grown on silica particles through atmospheric pressure cold plasma deposition; the sample surface was coated with a chemically adsorbed monomolecular layer. Samples were obtained which had a superhydrophobic property (with a water droplet contact angle of more than 150°) and a high average transmittance of about 90% (with wavelengths ranging from 400 nm to 780 nm).

  11. High Current Emission from Patterned Aligned Carbon Nanotubes Fabricated by Plasma-Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Cui, Linfan; Chen, Jiangtao; Yang, Bingjun; Jiao, Tifeng

    2015-12-01

    Vertically, carbon nanotube (CNT) arrays were successfully fabricated on hexagon patterned Si substrates through radio frequency plasma-enhanced chemical vapor deposition using gas mixtures of acetylene (C2H2) and hydrogen (H2) with Fe/Al2O3 catalysts. The CNTs were found to be graphitized with multi-walled structures. Different H2/C2H2 gas flow rate ratio was used to investigate the effect on CNT growth, and the field emission properties were optimized. The CNT emitters exhibited excellent field emission performance (the turn-on and threshold fields were 2.1 and 2.4 V/μm, respectively). The largest emission current could reach 70 mA/cm2. The emission current was stable, and no obvious deterioration was observed during the long-term stability test of 50 h. The results were relevant for practical applications based on CNTs.

  12. High Current Emission from Patterned Aligned Carbon Nanotubes Fabricated by Plasma-Enhanced Chemical Vapor Deposition.

    PubMed

    Cui, Linfan; Chen, Jiangtao; Yang, Bingjun; Jiao, Tifeng

    2015-12-01

    Vertically, carbon nanotube (CNT) arrays were successfully fabricated on hexagon patterned Si substrates through radio frequency plasma-enhanced chemical vapor deposition using gas mixtures of acetylene (C2H2) and hydrogen (H2) with Fe/Al2O3 catalysts. The CNTs were found to be graphitized with multi-walled structures. Different H2/C2H2 gas flow rate ratio was used to investigate the effect on CNT growth, and the field emission properties were optimized. The CNT emitters exhibited excellent field emission performance (the turn-on and threshold fields were 2.1 and 2.4 V/μm, respectively). The largest emission current could reach 70 mA/cm(2). The emission current was stable, and no obvious deterioration was observed during the long-term stability test of 50 h. The results were relevant for practical applications based on CNTs.

  13. Perovskite solar cells based on nanocolumnar plasma-deposited ZnO thin films.

    PubMed

    Ramos, F Javier; López-Santos, Maria C; Guillén, Elena; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Gonzalez-Elipe, Agustin R; Ahmad, Shahzada

    2014-04-14

    ZnO thin films having a nanocolumnar microstructure are grown by plasma-enhanced chemical vapor deposition at 423 K on pre-treated fluorine-doped tin oxide (FTO) substrates. The films consist of c-axis-oriented wurtzite ZnO nanocolumns with well-defined microstructure and crystallinity. By sensitizing CH3NH3PbI3 on these photoanodes a power conversion of 4.8% is obtained for solid-state solar cells. Poly(triarylamine) is found to be less effective when used as the hole-transport material, compared to 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD), while the higher annealing temperature of the perovskite leads to a better infiltration in the nanocolumnar structure and an enhancement of the cell efficiency.

  14. rf plasma oxidation of Ni thin films sputter deposited to generate thin nickel oxide layers

    SciTech Connect

    Hoey, Megan L.; Carlson, J. B.; Osgood, R. M. III; Kimball, B.; Buchwald, W.

    2010-10-11

    Nickel oxide (NiO) layers were formed on silicon (Si) substrates by plasma oxidation of nickel (Ni) film lines. This ultrathin NiO layer acted as a barrier layer to conduction, and was an integral part of a metal-insulator-metal (MIM) diode, completed by depositing gold (Au) on top of the oxide. The electrical and structural properties of the NiO thin film were examined using resistivity calculations, current-voltage (I-V) measurements and cross-sectional transmission electron microscopy (XTEM) imaging. The flow rate of the oxygen gas, chamber pressure, power, and exposure time and their influence on the characteristics of the NiO thin film were studied.

  15. Low-temperature synthesis of graphene on nickel foil by microwave plasma chemical vapor deposition

    SciTech Connect

    Kim, Y.; Song, W.; Lee, S. Y.; Jeon, C.; Jung, W.; Kim, M.; Park, C.-Y.

    2011-06-27

    Microwave plasma chemical vapor deposition (MPCVD) was employed to synthesize high quality centimeter scale graphene film at low temperatures. Monolayer graphene was obtained by varying the gas mixing ratio of hydrogen and methane to 80:1. Using advantages of MPCVD, the synthesis temperature was decreased from 750 deg. C down to 450 deg. C. Optical microscopy and Raman mapping images exhibited that a large area monolayer graphene was synthesized regardless of the temperatures. Since the overall transparency of 89% and low sheet resistances ranging from 590 to 1855 {Omega}/sq of graphene films were achieved at considerably low synthesis temperatures, MPCVD can be adopted in manufacturing future large-area electronic devices based on graphene film.

  16. Kinetic analysis of negative power deposition in inductive low pressure plasmas

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Mussenbrock, Thomas

    2017-02-01

    Negative power deposition in low pressure inductively coupled plasmas (ICPs) is investigated by means of an analytical model which couples Boltzmann’s equation and the quasi-stationary Maxwell’s equations. Exploiting standard Hilbert space methods an explicit solution for both, the electric field and the distribution function of the electrons for a bounded discharge configuration subject to an unsymmetrical excitation is found for the first time. The model is applied to a low pressure ICP discharge. In this context particularly the anomalous skin effect and the effect of phase mixing is discussed. The analytical solution is compared with results from electromagnetic full wave particle in cell simulations. Excellent agreement between the analytical and the numerical results is found.

  17. Carbon nanowalls grown by microwave plasma enhanced chemical vapor deposition during the carbonization of polyacrylonitrile fibers

    SciTech Connect

    Li Jiangling; Su Shi; Kundrat, Vojtech; Abbot, Andrew M.; Ye, Haitao; Zhou Lei; Mushtaq, Fajer; Ouyang Defang; James, David; Roberts, Darren

    2013-01-14

    We used microwave plasma enhanced chemical vapor deposition (MPECVD) to carbonize an electrospun polyacrylonitrile (PAN) precursor to form carbon fibers. Scanning electron microscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy were used to characterize the fibers at different evolution stages. It was found that MPECVD-carbonized PAN fibers do not exhibit any significant change in the fiber diameter, whilst conventionally carbonized PAN fibers show a 33% reduction in the fiber diameter. An additional coating of carbon nanowalls (CNWs) was formed on the surface of the carbonized PAN fibers during the MPECVD process without the assistance of any metallic catalysts. The result presented here may have a potential to develop a novel, economical, and straightforward approach towards the mass production of carbon fibrous materials containing CNWs.

  18. Deposition of titanium nitride and hydroxyapatite-based biocompatible composite by reactive plasma spraying

    NASA Astrophysics Data System (ADS)

    Roşu, Radu Alexandru; Şerban, Viorel-Aurel; Bucur, Alexandra Ioana; Dragoş, Uţu

    2012-02-01

    Titanium nitride is a bioceramic material successfully used for covering medical implants due to the high hardness meaning good wear resistance. Hydroxyapatite is a bioactive ceramic that contributes to the restoration of bone tissue, which together with titanium nitride may contribute to obtaining a superior composite in terms of mechanical and bone tissue interaction matters. The paper presents the experimental results in obtaining composite layers of titanium nitride and hydroxyapatite by reactive plasma spraying in ambient atmosphere. X-ray diffraction analysis shows that in both cases of powders mixtures used (10% HA + 90% Ti; 25% HA + 75% Ti), hydroxyapatite decomposition occurred; in variant 1 the decomposition is higher compared with the second variant. Microstructure of the deposited layers was investigated using scanning electron microscope, the surfaces presenting a lamellar morphology without defects such as cracks or microcracks. Surface roughness values obtained vary as function of the spraying distance, presenting higher values at lower thermal spraying distances.

  19. HRTEM analyses of the platinum nanoparticles prepared on graphite particles using coaxial arc plasma deposition

    NASA Astrophysics Data System (ADS)

    Miyazawa, Kun'ichi; Yoshitake, Masaru; Tanaka, Yumi

    2017-06-01

    Platinum nanoparticles with diameters less than ˜5 nm were prepared on graphite particles by the coaxial arc plasma deposition, and the structure of platinum nanoparticles was investigated using high-resolution transmission electron microscopy. {110} facets of platinum nanoparticles parallel to the surface (0001) planes of graphite particles were most frequently observed. The platinum nanoparticles were found to be anisotropically deformed from the bulk face-centered cubic structure, and the lattice parameters of platinum nanoparticles were estimated by assuming monoclinic structures. No correlation was observed between the diameter and the lattice parameters of the platinum nanoparticles. Approximately two-thirds of the platinum nanoparticles were compressively strained, and the other platinum nanoparticles showed the expanded unit cells. The cube root of monoclinic unit cell of the platinum nanoparticles varied from a compression of 5.9% to an expansion of 2.8% as compared with the bulk lattice constant of platinum.

  20. In situ nitrogen-doped graphene grown from polydimethylsiloxane by plasma enhanced chemical vapor deposition

    SciTech Connect

    Wang, Chundong; Zhou, Yungang; He, Lifang; Ng, Tsz-Wai; Hong, Guo; Wu, Qi-Hui; Gao, Fei; Lee, Chun-Sing; Zhang, Wenjun

    2013-01-21

    Due to its unique electronic properties and wide spectrum of promising applications, graphene has attracted much attention from scientists in various fields. Control and engineering of graphene’s semiconducting properties is considered to be the key of its applications in electronic devices. Here, we report a novel method to prepare in situ nitrogen-doped graphene by microwave plasma assisted chemical vapor deposition (CVD) using PDMS (Polydimethylsiloxane) as a solid carbon source. Based on this approach, the concentration of nitrogen-doping can be easily controlled via the flow rate of nitrogen during the CVD process. X-ray photoelectron spectroscopy results indicated that the nitrogen atoms doped into graphene lattice were mainly in the forms of pyridinic and pyrrolic structures. Moreover, first-principles calculations show that the incorporated nitrogen atoms can lead to p-type doping of graphene. This in situ approach provides a promising strategy to prepare graphene with controlled electronic properties.

  1. Low temperature plasma enhanced chemical vapor deposition of thin films combining mechanical stiffness, electrical insulation, and homogeneity in microcavities

    SciTech Connect

    Peter, S.; Guenther, M.; Hauschild, D.; Richter, F.

    2010-08-15

    The deposition of hydrogenated amorphous carbon (a-C:H) as well as hydrogenated amorphous silicon carbonitride (SiCN:H) films was investigated in view of a simultaneous realization of a minimum Young's modulus (>70 GPa), a high electrical insulation ({>=}1 MV/cm), a low permittivity and the uniform coverage of microcavities with submillimeter dimensions. For the a-C:H deposition the precursors methane (CH{sub 4}) and acetylene (C{sub 2}H{sub 2}) were used, while SiCN:H films were deposited from mixtures of trimethylsilane [SiH(CH{sub 3}){sub 3}] with nitrogen and argon. To realize the deposition of micrometer thick films with the aforementioned complex requirements at substrate temperatures {<=}200 deg. C, several plasma enhanced chemical vapor deposition methods were investigated: the capacitively coupled rf discharge and the microwave electron cyclotron resonance (ECR) plasma, combined with two types of pulsed substrate bias. SiCN:H films deposited at about 1 Pa from ECR plasmas with pulsed high-voltage bias best met the requirements. Pulsed biasing with pulse periods of about 1 {mu}s and amplitudes of about -2 kV was found to be most advantageous for the conformal low temperature coating of the microtrenches, thereby ensuring the required mechanical and insulating film properties.

  2. Blood compatibility of titanium-based coatings prepared by metal plasma immersion ion implantation and deposition

    NASA Astrophysics Data System (ADS)

    Tsyganov, I.; Maitz, M. F.; Wieser, E.

    2004-07-01

    Titanium with its natural oxide is known to be generally good biocompatible; and therefore, the suitability of some Ti-based coatings as coating for blood-contacting implants is analyzed. Layers of pure Ti, Ti oxynitrides (TiN 1- xO x with x=0.25, 0.50, and 0.75), and Ti oxides were deposited on oxidized Si from a plasma produced by cathodic arc evaporation under addition of N 2 and/or O 2 to the ambient near the substrate. The oxynitrides are crystalline with the fcc structure of TiN up to x=0.25. For x=0.5, a two-phase system of fcc TiN and fcc TiO has been found. In dependence on the deposition parameters, amorphous and crystalline layers (anatase + brookite or rutile) of TiO 2 have been obtained. The rutile layers were doped by implantation of P. The amorphous TiO 2 layers were implanted with Cr. To study the correlation between structure of the coating and blood compatibility, the clotting time of blood plasma as well as the adhesion and activation of blood platelets on the surface was investigated. TiN and oxynitrides showed the longest clotting time compared to rutile. Minimum platelet adhesion has been observed for pure TiO 2. Contrasting tendencies in the dependence of clotting time and platelet adhesion on the microstructure have been stated. However, for P +-doped rutile, both enhanced clotting time and improved platelet adhesion were observed. Platelet adherence and activation always showed similar trends.

  3. Evaporation of Droplets in Plasma Spray–Physical Vapor Deposition Based on Energy Compensation Between Self-Cooling and Plasma Heat Transfer

    NASA Astrophysics Data System (ADS)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-10-01

    In the plasma spray-physical vapor deposition process (PS-PVD), there is no obvious heating to the feedstock powders due to the free molecular flow condition of the open plasma jet. However, this is in contrast to recent experiments in which the molten droplets are transformed into vapor atoms in the open plasma jet. In this work, to better understand the heating process of feedstock powders in the open plasma jet of PS-PVD, an evaporation model of molten ZrO2 is established by examining the heat and mass transfer process of molten ZrO2. The results reveal that the heat flux in PS-PVD open plasma jet (about 106 W/m2) is smaller than that in the plasma torch nozzle (about 108 W/m2). However, the flying distance of molten ZrO2 in the open plasma jet is much longer than that in the plasma torch nozzle, so the heating in the open plasma jet cannot be ignored. The results of the evaporation model show that the molten ZrO2 can be partly evaporated by self-cooling, whereas the molten ZrO2 with a diameter <0.28 μm and an initial temperature of 3247 K can be completely evaporated within the axial distance of 450 mm by heat transfer.

  4. Evaporation of Droplets in Plasma Spray-Physical Vapor Deposition Based on Energy Compensation Between Self-Cooling and Plasma Heat Transfer

    NASA Astrophysics Data System (ADS)

    Liu, Mei-Jun; Zhang, Meng; Zhang, Qiang; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2017-08-01

    In the plasma spray-physical vapor deposition process (PS-PVD), there is no obvious heating to the feedstock powders due to the free molecular flow condition of the open plasma jet. However, this is in contrast to recent experiments in which the molten droplets are transformed into vapor atoms in the open plasma jet. In this work, to better understand the heating process of feedstock powders in the open plasma jet of PS-PVD, an evaporation model of molten ZrO2 is established by examining the heat and mass transfer process of molten ZrO2. The results reveal that the heat flux in PS-PVD open plasma jet (about 106 W/m2) is smaller than that in the plasma torch nozzle (about 108 W/m2). However, the flying distance of molten ZrO2 in the open plasma jet is much longer than that in the plasma torch nozzle, so the heating in the open plasma jet cannot be ignored. The results of the evaporation model show that the molten ZrO2 can be partly evaporated by self-cooling, whereas the molten ZrO2 with a diameter <0.28 μm and an initial temperature of 3247 K can be completely evaporated within the axial distance of 450 mm by heat transfer.

  5. Hollow electrode enhanced radio frequency glow plasma and its application to the chemical vapor deposition of microcrystalline silicon

    SciTech Connect

    Tabuchi, Toshihiro; Mizukami, Hiroyuki; Takashiri, Masayuki

    2004-09-01

    A hollow electrode enhanced radio frequency (rf) glow plasma excitation technique and its application to the chemical vapor deposition of microcrystalline silicon films have been studied. In this technique, the reactor has two types of hollow structure. One is a hollow counterelectrode, and the other serves as both a hollow counterelectrode and a hollow rf electrode. The application of these discharge types to semiconductor processing is studied in the case of plasma enhanced chemical vapor deposition of hydrogenated microcrystalline silicon thin films. High crystallinity, photosensitivity and a maximum deposition rate of 6.0 nm/s can all be achieved at plasma excitation frequency of 13.56 MHz and substrate temperature of 300 deg. C. Properties of these plasmas are investigated by observing the plasma emission pattern, optical emission spectrum analysis and electrical parameters of the rf electrode. It is found that the plasma technique using both types of hollow discharge not only results in higher intensity of SiH{sup *} and H{alpha} but also in much smaller self-bias voltage of the rf electrode. Faster processing of device grade hydrogenated microcrystalline silicon films can also be achieved under lower rf power compared to use of the hollow counterelectrode technique alone.

  6. Hollow electrode enhanced radio frequency glow plasma and its application to the chemical vapor deposition of microcrystalline silicon

    NASA Astrophysics Data System (ADS)

    Tabuchi, Toshihiro; Mizukami, Hiroyuki; Takashiri, Masayuki

    2004-09-01

    A hollow electrode enhanced radio frequency (rf) glow plasma excitation technique and its application to the chemical vapor deposition of microcrystalline silicon films have been studied. In this technique, the reactor has two types of hollow structure. One is a hollow counterelectrode, and the other serves as both a hollow counterelectrode and a hollow rf electrode. The application of these discharge types to semiconductor processing is studied in the case of plasma enhanced chemical vapor deposition of hydrogenated microcrystalline silicon thin films. High crystallinity, photosensitivity and a maximum deposition rate of 6.0 nm/s can all be achieved at plasma excitation frequency of 13.56 MHz and substrate temperature of 300°C. Properties of these plasmas are investigated by observing the plasma emission pattern, optical emission spectrum analysis and electrical parameters of the rf electrode. It is found that the plasma technique using both types of hollow discharge not only results in higher intensity of SiH* and Hα but also in much smaller self-bias voltage of the rf electrode. Faster processing of device grade hydrogenated microcrystalline silicon films can also be achieved under lower rf power compared to use of the hollow counterelectrode technique alone.

  7. Diamond thin films grown by microwave plasma assisted chemical vapor deposition

    SciTech Connect

    Leksono, M.

    1991-09-05

    Undoped and boron doped diamond thin films have been successfully grown by microwave plasma chemical vapor deposition from CH{sub 4}, H{sub 2}, and B{sub 2}H{sub 6}. The films were characterized using x- ray diffraction techniques, Raman and infrared spectroscopies, scanning electron microscopy, secondary ion mass spectrometry, and various electrical measurements. The deposition rates of the diamond films were found to increase with the CH{sub 4} concentration, substrate temperature, and/or pressure, and at 1.0% methane, 900{degrees}C, and 35 Torr, the value was measured to be 0.87 {mu}m/hour. The deposition rate for boron doped diamond films, decreases as the diborane concentration increases. The morphologies of the undoped diamond films are strongly related to the deposition parameters. As the temperature increases from 840 to 925 C, the film morphology changes from cubo-octahedron to cubic structures, while as the CH{sub 4} concentration increases from 0.5 to 1.0%, the morphology changes from triangular (111) faces with a weak preferred orientation to square (100) faces. At 2.0% Ch{sub 4} or higher the films become microcrystalline with cauliflower structures. Scanning electron microscopy analyses also demonstrate that selective deposition of undoped diamond films has been successfully achieved using a lift-off process with a resolution of at least 2 {mu}m. The x-ray diffraction and Raman spectra demonstrate that high quality diamond films have been achieved. The concentration of the nondiamond phases in the films grown at 1.0% CH{sub 4} can be estimated from the Raman spectra to be at less than 0.2% and increases with the CH{sub 4} concentration. The Raman spectra of the boron doped diamond films also indicate that the presence of boron tends to suppress the nondiamond phases in the films. Infrared spectra of the undoped diamond films show very weak CH stretch peaks which suggest that the hydrogen concentration is very low.

  8. Oxidation Protection Systems for Carbon-Carbon Composites Formed by Chemical Vapor Deposition and Plasma Assisted Chemical Vapor Deposition Techniques

    DTIC Science & Technology

    1992-04-22

    3 limitations. The most cow , ron technique used to deposit protective coatings is chemical vapor deposition (CVD). CVD is generally defined as "a... istalled in the gas feeding system. As illustrated in Figure 3-2, the vaporization device contains a Varian type tee adapter, in which ZrCl 4 powder was

  9. Argon–germane in situ plasma clean for reduced temperature Ge on Si epitaxy by high density plasma chemical vapor deposition

    DOE PAGES

    Douglas, Erica A.; Sheng, Josephine J.; Verley, Jason C.; ...

    2015-06-04

    We found that the demand for integration of near infrared optoelectronic functionality with silicon complementary metal oxide semiconductor (CMOS) technology has for many years motivated the investigation of low temperature germanium on silicon deposition processes. Our work describes the development of a high density plasma chemical vapor deposition process that uses a low temperature (<460 °C) in situ germane/argon plasma surface preparation step for epitaxial growth of germanium on silicon. It is shown that the germane/argon plasma treatment sufficiently removes SiOx and carbon at the surface to enable germanium epitaxy. Finally, the use of this surface preparation step demonstrates anmore » alternative way to produce germanium epitaxy at reduced temperatures, a key enabler for increased flexibility of integration with CMOS back-end-of-line fabrication.« less

  10. Argon–germane in situ plasma clean for reduced temperature Ge on Si epitaxy by high density plasma chemical vapor deposition

    SciTech Connect

    Douglas, Erica A.; Sheng, Josephine J.; Verley, Jason C.; Carroll, Malcolm S.

    2015-06-04

    We found that the demand for integration of near infrared optoelectronic functionality with silicon complementary metal oxide semiconductor (CMOS) technology has for many years motivated the investigation of low temperature germanium on silicon deposition processes. Our work describes the development of a high density plasma chemical vapor deposition process that uses a low temperature (<460 °C) in situ germane/argon plasma surface preparation step for epitaxial growth of germanium on silicon. It is shown that the germane/argon plasma treatment sufficiently removes SiOx and carbon at the surface to enable germanium epitaxy. Finally, the use of this surface preparation step demonstrates an alternative way to produce germanium epitaxy at reduced temperatures, a key enabler for increased flexibility of integration with CMOS back-end-of-line fabrication.

  11. A solid-state nuclear magnetic resonance study of post-plasma reactions in organosilicone microwave plasma-enhanced chemical vapor deposition (PECVD) coatings.

    PubMed

    Hall, Colin J; Ponnusamy, Thirunavukkarasu; Murphy, Peter J; Lindberg, Mats; Antzutkin, Oleg N; Griesser, Hans J

    2014-06-11

    Plasma-polymerized organosilicone coatings can be used to impart abrasion resistance and barrier properties to plastic substrates such as polycarbonate. Coating rates suitable for industrial-scale deposition, up to 100 nm/s, can be achieved through the use of microwave plasma-enhanced chemical vapor deposition (PECVD), with optimal process vapors such as tetramethyldisiloxane (TMDSO) and oxygen. However, it has been found that under certain deposition conditions, such coatings are subject to post-plasma changes; crazing or cracking can occur anytime from days to months after deposition. To understand the cause of the crazing and its dependence on processing plasma parameters, the effects of post-plasma reactions on the chemical bonding structure of coatings deposited with varying TMDSO-to-O2 ratios was studied with (29)Si and (13)C solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) using both single-pulse and cross-polarization techniques. The coatings showed complex chemical compositions significantly altered from the parent monomer. (29)Si MAS NMR spectra revealed four main groups of resonance lines, which correspond to four siloxane moieties (i.e., mono (M), di (D), tri (T), and quaternary (Q)) and how they are bound to oxygen. Quantitative measurements showed that the ratio of TMDSO to oxygen could shift the chemical structure of the coating from 39% to 55% in Q-type bonds and from 28% to 16% for D-type bonds. Post-plasma reactions were found to produce changes in relative intensities of (29)Si resonance lines. The NMR data were complemented by Fourier transform infrared (FTIR) spectroscopy. Together, these techniques have shown that the bonding environment of Si is drastically altered by varying the TMDSO-to-O2 ratio during PECVD, and that post-plasma reactions increase the cross-link density of the silicon-oxygen network. It appears that Si-H and Si-OH chemical groups are the most susceptible to post-plasma reactions. Coatings produced at a

  12. Precursor-Surface Reactions in Plasma Deposition of Silicon Thin Films

    NASA Astrophysics Data System (ADS)

    Bakos, Tamas

    2005-03-01

    Device-quality hydrogenated amorphous silicon (a-Si:H) thin films are usually grown by plasma deposition under conditions where the SiH3 radical is the dominant deposition precursor. In this presentation, we report results of first-principles density functional theory calculations on the interactions of the SiH3 radical with the crystalline Si(100)-(2x1):H surface in conjunction with molecular-dynamics simulations of a-Si:H thin film growth by SiH3 radicals, which elucidate the pathways and energetics of surface reactions that govern important film properties. In particular, we show that an SiH3 radical can insert into strained surface Si-Si dimer bonds, abstract surface H through an Eley-Rideal mechanism, and passivate surface dangling bonds; these reactions follow exothermic and barrierless pathways that lead to a temperature-independent growth rate in agreement with experimental measurements. We also identify a thermally activated surface H abstraction process, in which the SiH3 radical diffuses through overcoordinated surface Si atoms until it encounters a favorable site for H abstraction; the diffusion and H-abstraction steps have commensurate activation barriers. This mechanism explains partly the reduction of the film H content at elevated substrate temperatures.

  13. Spectroscopic Study of Plasma Polymerized a-C:H Films Deposited by a Dielectric Barrier Discharge

    PubMed Central

    Chandrashekaraiah, Thejaswini Halethimmanahally; Bogdanowicz, Robert; Rühl, Eckart; Danilov, Vladimir; Meichsner, Jürgen; Thierbach, Steffen; Hippler, Rainer

    2016-01-01

    Plasma polymerized a-C:H thin films have been deposited on Si (100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using C2Hm/Ar (m = 2, 4, 6) gas mixtures. The deposited films were characterized by Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS), Raman spectroscopy, and ellipsometry. FT-IRRAS revealed the presence of sp3 and sp2 C–H stretching and C–H bending vibrations of bonds in the films. The presence of D and G bands was confirmed by Raman spectroscopy. Thin films obtained from C2H4/Ar and C2H6/Ar gas mixtures have ID/IG ratios of 0.45 and 0.3, respectively. The refractive indices were 2.8 and 3.1 for C2H4/Ar and C2H6/Ar films, respectively, at a photon energy of 2 eV. PMID:28773715

  14. Plasma-assisted physical vapor deposition surface treatments for tribological control

    NASA Technical Reports Server (NTRS)

    Spalvins, Talivaldis

    1990-01-01

    In any mechanical or engineering system where contacting surfaces are in relative motion, adhesion, wear, and friction affect reliability and performance. With the advancement of space age transportation systems, the tribological requirements have dramatically increased. This is due to the optimized design, precision tolerance requirements, and high reliability expected for solid lubricating films in order to withstand hostile operating conditions (vacuum, high-low temperatures, high loads, and space radiation). For these problem areas the ion-assisted deposition/modification processes (plasma-based and ion beam techniques) offer the greatest potential for the synthesis of thin films and the tailoring of adherence and chemical and structural properties for optimized tribological performance. The present practices and new approaches of applying soft solid lubricant and hard wear resistant films to engineering substrates are reviewed. The ion bombardment treatments have increased film adherence, lowered friction coefficients, and enhanced wear life of the solid lubricating films such as the dichalcogenides (MoS2) and the soft metals (Au, Ag, Pb). Currently, sputtering is the preferred method of applying MoS2 films; and ion plating, the soft metallic films. Ultralow friction coefficients (less than 0.01) were achieved with sputtered MoS2. Further, new diamond-like carbon and BN lubricating films are being developed by using the ion assisted deposition techniques.

  15. Plasma deposition of amorphous silicon carbide thin films irradiated with neutrons

    NASA Astrophysics Data System (ADS)

    Huran, J.; Bohacek, P.; Kucera, M.; Kleinova, A.; Sasinkova, V.; IEE SAS, Bratislava, Slovakia Team; Polymer Institute, SAS, Bratislava, Slovakia Team; Institute of Chemistry, SAS, Bratislava, Slovakia Team

    2015-09-01

    Amorphous silicon carbide and N-doped silicon carbide thin films were deposited on P-type Si(100) wafer by plasma enhanced chemical vapor deposition (PECVD) technology using silane, methane, ammonium and argon gases. The concentration of elements in the films was determined by RBS and ERDA method. Chemical compositions were analyzed by FTIR spectroscopy. Photoluminescence properties were studied by photoluminescence spectroscopy (PL). Irradiation of samples with various neutron fluencies was performed at room temperature. The films contain silicon, carbon, hydrogen, nitrogen and small amount of oxygen. From the IR spectra, the films contained Si-C, Si-H, C-H, Si-N, N-H and Si-O bonds. No significance effect on the IR spectra after neutron irradiation was observed. PL spectroscopy results of films showed decreasing PL intensity after neutron irradiation and PL intensity decreased with increased neutron fluencies. The measured current of the prepared structures increased after irradiation with neutrons and rise up with neutron fluencies.

  16. Characterization of diamond-like nanocomposite thin films grown by plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Santra, T. S.; Liu, C. H.; Bhattacharyya, T. K.; Patel, P.; Barik, T. K.

    2010-06-01

    Diamond-like nanocomposite (DLN) thin films, comprising the networks of a-C:H and a-Si:O were deposited on pyrex glass or silicon substrate using gas precursors (e.g., hexamethyldisilane, hexamethyldisiloxane, hexamethyldisilazane, or their different combinations) mixed with argon gas, by plasma enhanced chemical vapor deposition technique. Surface morphology of DLN films was analyzed by atomic force microscopy. High-resolution transmission electron microscopic result shows that the films contain nanoparticles within the amorphous structure. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) were used to determine the structural change within the DLN films. The hardness and friction coefficient of the films were measured by nanoindentation and scratch test techniques, respectively. FTIR and XPS studies show the presence of CC, CH, SiC, and SiH bonds in the a-C:H and a-Si:O networks. Using Raman spectroscopy, we also found that the hardness of the DLN films varies with the intensity ratio ID/IG. Finally, we observed that the DLN films has a better performance compared to DLC, when it comes to properties like high hardness, high modulus of elasticity, low surface roughness and low friction coefficient. These characteristics are the critical components in microelectromechanical systems (MEMS) and emerging nanoelectromechanical systems (NEMS).

  17. Electrical performance of low cost cathodes prepared by plasma sputtering deposition in microbial fuel cells.

    PubMed

    Lefebvre, Olivier; Tang, Zhe; Fung, Martin P H; Chua, Daniel H C; Chang, In Seop; Ng, How Y

    2012-01-15

    Microbial fuel cells (MFCs) could potentially be utilized for a variety of applications in the future from biosensors to wastewater treatment. However, the amount of costly platinum (Pt) used as a catalyst should be minimized via innovative deposition methods such as sputtering. In addition, alternative and low-cost catalysts, such as cobalt (Co), should be sought. In this study, ultra low Pt or Co cathodes (0.1 mg cm(-2)) were manufactured by plasma sputtering deposition and scanning electron micrographs revealed nano-clusters of metal catalyst in a porous structure favorable to the three-phase heterogeneous catalytic reaction. When operated in single-chamber air-cathode MFCs, sputtered-Co cathodes generated on average the same power as sputtered-Pt cathodes (0.27 mW cell(-1)) and only 27% less than conventional Pt-ink cathodes with a catalyst load 5 times higher (0.5 mg cm(-2)). Finally, microscopy and molecular analyses showed evidence of biocatalysis activity on metal-free cathodes.

  18. Application of a single crystal chemical vapor deposition diamond detector for deuteron plasma neutron measurement

    NASA Astrophysics Data System (ADS)

    Xie, Xufei; Yuan, Xi; Zhang, Xing; Chen, Zhongjing; Peng, Xingyu; Du, Tengfei; Li, Tao; Hu, Zhimeng; Cui, Zhiqiang; Chen, Jinxiang; Li, Xiangqing; Zhang, Guohui; Fan, Tieshuan; Yuan, Guoliang; Yang, Jinwei; Yang, Qingwei

    2014-10-01

    A single crystal chemical vapor deposition (scCVD) diamond detector has been characterized and employed for the neutron measurement at the HL-2A tokamak device. The scCVD diamond detector has been deposited with 5 μm of lithium fluoride (LiF) layer to enhance the sensitivity to thermal neutrons. Time stability of the detector has been studied with α-source and good performance has been found for more than 12 h. Neutron irradiations have been performed in four quasi-monoenergetic neutron fields in the energy range from 2.50 MeV to 16.03 MeV. The measured response function of the scCVD diamond detector to 14.13 MeV neutrons shows a narrow 12C (n, α)9Be reaction peak which is well isolated from other structures by about 1 MeV in energy, indicating the great potential as a fast neutron spectrometer. Neutron measurement of deuterium plasma discharge was established at the HL-2A tokamak device, and good consistence has been revealed among this detector signal and other related signals.

  19. Comparison of pulsed and downstream deposition of fluorocarbon materials from C3F8 and c-C4F8 plasmas

    NASA Astrophysics Data System (ADS)

    Martin, Ina T.; Malkov, Galiya Sh.; Butoi, Carmen I.; Fisher, Ellen R.

    2004-03-01

    Materials deposited in continuous wave (cw) and pulsed low-pressure octafluoropropane (C3F8) and octafluorocyclobutane (c-C4F8) plasmas were characterized using Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy, static contact angle measurements, spectroscopic ellipsometry, and scanning electron microscopy (SEM). Fluorocarbon (FC) materials deposited in pulsed plasmas were less crosslinked than those deposited in cw plasmas with equivalent input powers. Within each system, higher F/C ratio materials were deposited by lowering the plasma input power/duty cycle. Using downstream depositions had a similar effect on film composition, but also resulted in decreased deposition rates. SEM analysis showed that decreases in the flexibility of the fluorocarbon films were correlated with increases in the percent of crosslinking. Additionally, the smoothness of the film surfaces suggests that polymerization processes occur on the substrate surface. Overall, films deposited in C4F8 plasmas were more crosslinked and less flexible than those deposited in C3F8 plasmas under the same conditions. The composition of the deposited FC films is correlated to the nature and relative concentrations of nascent ions previously measured in these plasma systems using plasma ion mass spectrometry. .

  20. Electron cyclotron resonance microwave plasma deposition of a-Si:H and a-SiC:H films

    NASA Technical Reports Server (NTRS)

    Shing, Y. H.; Pool, F. S.

    1991-01-01

    The paper reports electron cyclotron resonance (ECR) deposition of a-Si:H and a-SiC:H thin films using SiH4, CH4, and hydrogen mixed gas plasmas. The ECR deposition conditions were investigated in the pressure region of 0.1 to 100 mtorr, and the film properties were characterized by light and dark conductivity measurements, XRD, Raman spectroscopy, optical transmission, and IR spectroscopy. In addition, the hydrogen dilution effect on ECR-deposited a-SiC:H was investigated.

  1. Organometallic chemical vapor deposition of silicon nitride films enhanced by atomic nitrogen generated from surface-wave plasma

    SciTech Connect

    Okada, H.; Kato, M.; Ishimaru, T.; Sekiguchi, H.; Wakahara, A.; Furukawa, M.

    2014-02-20

    Organometallic chemical vapor deposition of silicon nitride films enhanced by atomic nitrogen generated from surface-wave plasma is investigated. Feasibility of precursors of triethylsilane (TES) and bis(dimethylamino)dimethylsilane (BDMADMS) is discussed based on a calculation of bond energies by computer simulation. Refractive indices of 1.81 and 1.71 are obtained for deposited films with TES and BDMADMS, respectively. X-ray photoelectron spectroscopy (XPS) analysis of the deposited film revealed that TES-based film coincides with the stoichiometric thermal silicon nitride.

  2. Annealing and oxidation of silicon oxide films prepared by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Chen, X. Y.; Lu, Y. F.; Tang, L. J.; Wu, Y. H.; Cho, B. J.; Xu, X. J.; Dong, J. R.; Song, W. D.

    2005-01-01

    We have investigated phase separation, silicon nanocrystal (Si NC) formation and optical properties of Si oxide (SiOx, 0deposited by plasma-enhanced chemical vapor deposition at different nitrous-oxide/silane flow ratios. The physical and optical properties of the SiOx films were studied as a result of high-vacuum annealing and thermal oxidation. X-ray photoelectron spectroscopy (XPS) reveals that the as-deposited films have a random-bonding or continuous-random-network structure with different oxidation states. After annealing at temperatures above 1000 °C, the intermediate Si continuum in XPS spectra (referring to the suboxide) split to Si peaks corresponding to SiO2 and elemental Si. This change indicates the phase separation of the SiOx into more stable SiO2 and Si clusters. Raman, high-resolution transmission electron microscopy and optical absorption confirmed the phase separation and the formation of Si NCs in the films. The size of Si NCs increases with increasing Si concentration in the films and increasing annealing temperature. Two photoluminescence (PL) bands were observed in the films after annealing. The ultraviolet (UV)-range PL with a peak fixed at 370-380 nm is independent of Si concentration and annealing temperature, which is a characteristic of defect states. Strong PL in red range shows redshifts from ˜600 to 900 nm with increasing Si concentration and annealing temperature, which supports the quantum confinement model. After oxidation of the high-temperature annealed films, the UV PL was almost quenched while the red PL shows continuous blueshifts with increasing oxidation time. The different oxidation behaviors further relate the UV PL to the defect states and the red PL to the recombination of quantum-confined excitions.

  3. Plasma-enhanced chemical vapor deposition synthesis of vertically oriented graphene nanosheets.

    PubMed

    Bo, Zheng; Yang, Yong; Chen, Junhong; Yu, Kehan; Yan, Jianhua; Cen, Kefa

    2013-06-21

    Vertically oriented graphene (VG) nanosheets have attracted growing interest for a wide range of applications, from energy storage, catalysis and field emission to gas sensing, due to their unique orientation, exposed sharp edges, non-stacking morphology, and huge surface-to-volume ratio. Plasma-enhanced chemical vapor deposition (PECVD) has emerged as a key method for VG synthesis; however, controllable growth of VG with desirable characteristics for specific applications remains a challenge. This paper attempts to summarize the state-of-the-art research on PECVD growth of VG nanosheets to provide guidelines on the design of plasma sources and operation parameters, and to offer a perspective on outstanding challenges that need to be overcome to enable commercial applications of VG. The review starts with an overview of various types of existing PECVD processes for VG growth, and then moves on to research on the influences of feedstock gas, temperature, and pressure on VG growth, substrate pretreatment, the growth of VG patterns on planar substrates, and VG growth on cylindrical and carbon nanotube (CNT) substrates. The review ends with a discussion on challenges and future directions for PECVD growth of VG.

  4. Growth of ultrananocrystalline diamond film by DC Arcjet plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Chen, G. C.; Li, B.; Yan, Z. Q.; Liu, J.; Lu, F. X.; Ye, H.

    2012-06-01

    Self-standing diamond films were grown by DC Arcjet plasma enhanced chemical vapor deposition (CVD). The feed gasses were Ar/H2/CH4, in which the flow ratio of CH4 to H2 (F/F) was varied from 5% to 20%. Two distinct morphologies were observed by scanning electron microscope (SEM), i.e. the "pineapple-like" morphology and the "cauliflower-like" morphology. It was found that the morphologies of the as-grown films are strongly dependent on the flow ratio of CH4 to H2 in the feed gasses. High resolution transmission electron microscope (HRTEM) survey results revealed that there were nanocrystalline grains within the "pineapple-like" films whilst there were ultrananocrystalline grains within "cauliflower-like" films. X-ray diffraction (XRD) results suggested that (110) crystalline plane was the dominant surface in the "cauliflower-like" films whilst (100) crystalline plane was the dominant surface in the "pineapple-like" films. Raman spectroscopy revealed that nanostructured carbon features could be observed in both types of films. Plasma diagnosis was carried out in order to understand the morphology dependent growth mechanism. It could be concluded that the film morphology was strongly influenced by the density of gas phases. The gradient of C2 radical was found to be different along the growth direction under the different growth conditions.

  5. Passivation of aluminum nanoparticles by plasma-enhanced chemical vapor deposition for energetic nanomaterials.

    PubMed

    Shahravan, Anaram; Desai, Tapan; Matsoukas, Themis

    2014-05-28

    We have produced passivating coatings on 80-nm aluminum particles by plasma-enhanced chemical vapor deposition (PECVD). Three organic precursors--isopropyl alcohol, toluene, and perfluorodecalin--were used to fabricate thin films with thicknesses ranging from 5 nm to 30 nm. The coated samples and one untreated sample were exposed to 85% humidity at 25 °C for two months, and the active Al content was determined by thermogravimetric analysis (TGA) in the presence of oxygen. The results were compared with an uncoated sample stored in a glovebox under argon for the same period. We find that all three coatings provide protection against humidity, compared to the control, and their efficacy ranks in the following order: isopropyl alcohol < toluene < perfluorodecalin. This order also correlates with increasing water contact angle of the three solid coatings. The amount of heat released in the oxidation, measured by differential scanning calorimetry (DSC), was found to increase in the same order. Perfluorodecalin resulted in providing the best protection, and it produced the maximum enthalpy of combustion, ΔH = 4.65 kJ/g. This value is higher than that of uncoated aluminum stored in the glovebox, indicating that the coatings promote more complete oxidation of the core. Overall, we conclude that the plasma polymer coatings of this study are suitable passivating thin film for aluminum nanoparticles by providing protection against oxidation while facilitating the complete oxidation of the metallic core at elevated temperature.

  6. Epithelial cell morphology and adhesion on diamond films deposited and chemically modified by plasma processes.

    PubMed

    Rezek, Bohuslav; Ukraintsev, Egor; Krátká, Marie; Taylor, Andrew; Fendrych, Frantisek; Mandys, Vaclav

    2014-09-01

    The authors show that nanocrystalline diamond (NCD) thin films prepared by microwave plasma enhanced chemical vapor deposition apparatus with a linear antenna delivery system are well compatible with epithelial cells (5637 human bladder carcinoma) and significantly improve the cell adhesion compared to reference glass substrates. This is attributed to better adhesion of adsorbed layers to diamond as observed by atomic force microscopy (AFM) beneath the cells. Moreover, the cell morphology can be adjusted by appropriate surface treatment of diamond by using hydrogen and oxygen plasma. Cell bodies, cytoplasmic rims, and filopodia were characterized by Peakforce AFM. Oxidized NCD films perform better than other substrates under all conditions (96% of cells adhered well). A thin adsorbed layer formed from culture medium and supplemented with fetal bovine serum (FBS) covered the diamond surface and played an important role in the cell adhesion. Nevertheless, 50-100 nm large aggregates formed from the RPMI medium without FBS facilitated cell adhesion also on hydrophobic hydrogenated NCD (increase from 23% to 61%). The authors discuss applicability for biomedical uses.

  7. Analyzing the contents of residual and plasma-supporting gases inside a vacuum deposition unit chamber

    NASA Astrophysics Data System (ADS)

    Mikheev, A. Ye; Kharlamov, V. A.; Kruchek, S. D.; Cherniatina, A. A.; Khomenko, I. I.

    2015-01-01

    The paper describes a quadruple mass-spectrometer method, which is used to analyze the content of residual gas in a vacuum chamber of the ARM NTM (Automatised Working Area) ion-plasma unit. This unit is used to perfect the magnetron deposition process for coating radio-reflecting surfaces. The intake of pure argon into the chamber revealed up to 0.3 % of impurities in the plasma-supporting gas, including 0.02 % of water and oxygen. A significant presence of hydrocarbon gases is explained by the presence of solvents sorbed in rubber washers, joints of internal equipment, and other components inside the chamber. In order to decrease the level of impurities in the plasmasupporting atmosphere inside the chamber and improve the composition and properties of the coatings, it is necessary to take additional measures to cleanse and degas the surface of the chamber from condensation products and hydrocarbon compounds. To provide a minimal level of impurities in the coated surfaces it is vital to clean and degas the surfaces of the chamber, removing residual moisture and hydrocarbon compounds.

  8. Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride Using a Novel Silylamine Precursor.

    PubMed

    Park, Jae-Min; Jang, Se Jin; Yusup, Luchana L; Lee, Won-Jun; Lee, Sang-Ick

    2016-08-17

    We report the plasma-enhanced atomic layer deposition (PEALD) of silicon nitride thin film using a silylamine compound as the silicon precursor. A series of silylamine compounds were designed by replacing SiH3 groups in trisilylamine by dimethylaminomethylsilyl or trimethylsilyl groups to obtain sufficient thermal stability. The silylamine compounds were synthesized through redistribution, amino-substitution, lithiation, and silylation reactions. Among them, bis(dimethylaminomethylsilyl)trimethylsilyl amine (C9H29N3Si3, DTDN2-H2) was selected as the silicon precursor because of the lowest bond dissociation energy and sufficient vapor pressures. The energies for adsorption and reaction of DTDN2-H2 with the silicon nitride surface were also calculated by density functional theory. PEALD silicon nitride thin films were prepared using DTDN2-H2 and N2 plasma. The PEALD process window was between 250 and 400 °C with a growth rate of 0.36 Å/cycle. The best film quality was obtained at 400 °C with a RF power of 100 W. The PEALD film prepared showed good bottom and sidewall coverages of ∼80% and ∼73%, respectively, on a trench-patterned wafer with an aspect ratio of 5.5.

  9. Synthesis of few-layer graphene via microwave plasma-enhanced chemical vapour deposition.

    PubMed

    Malesevic, Alexander; Vitchev, Roumen; Schouteden, Koen; Volodin, Alexander; Zhang, Liang; Tendeloo, Gustaaf Van; Vanhulsel, Annick; Haesendonck, Chris Van

    2008-07-30

    If graphene is ever going to live up to the promises of future nanoelectronic devices, an easy and cheap route for mass production is an essential requirement. A way to extend the capabilities of plasma-enhanced chemical vapour deposition to the synthesis of freestanding few-layer graphene is presented. Micrometre-wide flakes consisting of four to six atomic layers of stacked graphene sheets have been synthesized by controlled recombination of carbon radicals in a microwave plasma. A simple and highly reproducible technique is essential, since the resulting flakes can be synthesized without the need for a catalyst on the surface of any substrate that withstands elevated temperatures up to 700 °C. A thorough structural analysis of the flakes is performed with electron microscopy, x-ray diffraction, Raman spectroscopy and scanning tunnelling microscopy. The resulting graphene flakes are aligned vertically to the substrate surface and grow according to a three-step process, as revealed by the combined analysis of electron microscopy and x-ray photoelectron spectroscopy.

  10. Thermal stability studies of plasma sprayed yttrium oxide coatings deposited on pure tantalum substrate

    NASA Astrophysics Data System (ADS)

    Nagaraj, A.; Anupama, P.; Mukherjee, Jaya; Sreekumar, K. P.; Satpute, R. U.; Padmanabhan, P. V. A.; Gantayet, L. M.

    2010-02-01

    Plasma sprayed Yttrium oxide is used for coating of crucibles and moulds that are used at high temperature to handle highly reactive molten metals like uranium, titanium, chromium, and beryllium. The alloy bond layer is severely attacked by the molten metal. This commonly used layer contributes to the impurity addition to the pure liquid metal. Yttrium oxide was deposited on tantalum substrates (25 mm × 10mm × 1mm thk and 40 mm × 8mm × 1mm thk) by atmospheric plasma spray technique with out any bond coat using optimized coating parameters. Resistance to thermal shock was evaluated by subjecting the coated specimens, to controlled heating and cooling cycles between 300K to 1600K in an induction furnace in argon atmosphere having <= 0.1ppm of oxygen. The experiments were designed to examine the sample tokens by both destructive and non-destructive techniques, after a predetermined number of thermal cycles. The results upto 24 thermal cycles of 25 mm × 10mm × 1mm thk coupons and upto 6 cycles of 40 mm × 8mm × 1mm thk coupons are discussed. The coatings produced with the optimized parameters were found to exhibit excellent thermal shock resistance.

  11. Growth of Er-doped silicon using metalorganics by plasma-enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Andry, P. S.; Varhue, W. J.; Ladipo, F.; Ahmed, K.; Adams, E.; Lavoie, M.; Klein, P. B.; Hengehold, R.; Hunter, J.

    1996-07-01

    Epitaxial growth of Er-doped silicon films has been performed by plasma-enhanced chemical vapor deposition at low temperature (430 °C) using an electron cyclotron resonance source. The goal was to incorporate an optically active center, erbium surrounded by nitrogen, through the use of the metalorganic compound tris (bis trimethyl silyl amido) erbium. Films were analyzed by Rutherford backscattering spectrometry, secondary ion mass spectroscopy, and high resolution x-ray diffraction. The characteristic 1.54 μm emission was observed by photoluminescence spectroscopy. Previous attempts to incorporate the complex (ErO6) using tris (2,2,6,6-tetramethyl- 3,5-heptanedionato) erbium (III) indicated that excessive carbon contamination lowered epitaxial quality and reduced photoluminescent intensity. In this study, chemical analysis of the films also revealed a large carbon concentration, however, the effect on epitaxial quality was much less destructive. A factorial design experiment was performed whose analysis identified the key processing parameters leading to high quality luminescent films. Hydrogen was found to be a major cause of crystal quality degradation in our metalorganic plasma-enhanced process.

  12. Influence of organic surface chemistry on the nucleation of plasma deposited SiO x films

    NASA Astrophysics Data System (ADS)

    Hoppe, C.; Mitschker, F.; Giner, I.; de los Arcos, T.; Awakowicz, P.; Grundmeier, G.

    2017-05-01

    The nucleation and film growth of SiO x plasma polymer films as a function of the substrate surface chemistry are analysed by a combination of microscopic, spectroscopic and electrochemical techniques. Self-assembled organothiol monolayers (SAMs) surfaces with different terminating groups (methyl, carboxyl- and trimethoxysilane groups) on Au(111) serve as a model system. Ultra-thin SiO x films with thickness ranging from 0.4 to 1.4 nm were deposited by microwave plasma in a mixture of HMDSO and O2. The changes in surface, interface and thin film chemistry are characterized by PM-IRRAS. Cyclic voltammetry with ferricyanide as a redox system is used to probe the defect density of the bare SAMs and the SiO x -covered SAMs. Furthermore, the evolution of the SiO x surface morphology for increasing film thickness as function of the substrate chemical termination is investigated by AFM. A strong influence of the surface chemistry on the SiO x nucleation and film growth is observed. While the methyl and carboxyl terminated SAMs are degraded during the nucleation leading to defect rich ultrathin films, the trimethoxysilane group protects the aliphatic chain of the SAM and leads to much better barrier properties of the ultra-thin SiO x -films. A mechanistic explanation of the results is provided.

  13. Magnetically controlled deposition of metals using gas plasma. Quarterly progress report, April--June 1994

    SciTech Connect

    Woodall, D.M.; Lemmon, E.C.

    1994-07-01

    Thin layers of secondary material are plated on substrates either by plating or spraying processes. Plating operations produce large amounts of hazardous liquid wastes. Spraying, while one of the less waste intensive methods, produces ``over spray`` which is waste that is a result of the uncontrolled nature of the spray stream. In many cases the over spray produces a hazardous waste. Spray coating is a mature process with many uses. Material can be deposited utilizing spraying technology in three basic ways: ``Flame spraying;`` direct spraying of molten metals; and/or plasma spraying. This project is directed at controlling the plasma spraying process and thereby minimizing the waste generated in that process. Examples of spraying applications that may benefit substantially from this technology are: (1) preparing printed circuit boards; and (2) tinning circuit boards with lead in preparation for soldering components. There are many applications of spraying technology that can benefit from a controlled spraying scheme. They include: (1) titanium coating on bio-implants; (2) wear-tolerant ceramic thermal barriers using partially stabilized zirconia (PSZ); (3) alumina and alumina-titania wear resistant-coatings: and (4) ceramic superconductor manufacture using Hollow Spherical Powders.

  14. Deposition of Antimicrobial Copper-Rich Coatings on Polymers by Atmospheric Pressure Jet Plasmas

    PubMed Central

    Kredl, Jana; Kolb, Juergen F.; Schnabel, Uta; Polak, Martin; Weltmann, Klaus-Dieter; Fricke, Katja

    2016-01-01

    Inanimate surfaces serve as a permanent reservoir for infectious microorganisms, which is a growing problem in areas in everyday life. Coating of surfaces with inorganic antimicrobials, such as copper, can contribute to reduce the adherence and growth of microorganisms. The use of a DC operated air plasma jet for the deposition of copper thin films on acrylonitrile butadiene styrene (ABS) substrates is reported. ABS is a widespread material used in consumer applications, including hospitals. The influence of gas flow rate and input current on thin film characteristics and its bactericidal effect have been studied. Results from X-ray photoelectron spectroscopy (XPS) and atomic force microscopy confirmed the presence of thin copper layers on plasma-exposed ABS and the formation of copper particles with a size in the range from 20 to 100 nm, respectively. The bactericidal properties of the copper-coated surfaces were tested against Staphylococcus aureus. A reduction in growth by 93% compared with the attachment of bacteria on untreated samples was observed for coverage of the surface with 7 at. % copper. PMID:28773396

  15. Rutile-structured TiO{sub 2} deposited by plasma enhanced atomic layer deposition using tetrakis(dimethylamino)titanium precursor on in-situ oxidized Ru electrode

    SciTech Connect

    Pointet, John; Gonon, Patrice; Latu-Romain, Lawrence; Bsiesy, Ahmad Vallée, Christophe

    2014-01-15

    In this work, tetrakis(dimethylamino)titanium precursor as well as in-situ oxidized ruthenium bottom electrode were used to grow rutile-structured titanium dioxide thin layers by plasma enhanced atomic layer deposition. Metal–insulator–metal capacitors have been elaborated in order to study the electrical properties of the device. It is shown that this process leads to devices exhibiting excellent results in terms of dielectric constant and leakage current.

  16. Hydrophobicity enhancement of Al2O3 thin films deposited on polymeric substrates by atomic layer deposition with perfluoropropane plasma treatment

    NASA Astrophysics Data System (ADS)

    Ali, Kamran; Choi, Kyung-Hyun; Kim, Chang Young; Doh, Yang Hoi; Jo, Jeongdai

    2014-06-01

    The optoelectronics devices such as organic light emitting diodes are greatly vulnerable to moisture, which reduces their functionality and life cycle. The Al2O3 thin films are mostly used as barrier coatings in such electronic devices to protect them from water vapors. The performance of the Al2O3 barrier films can be improved by enhancing their hydrophobicity. Greater the hydrophobicity of the barrier films, greater will be their protection against water vapors. This paper reports on the enhancement of hydrophobicity of Al2O3 thin films through perfluoropropane (C3F8) plasma treatment. Firstly, good quality Al2O3 films have been fabricated through atomic layer deposition (ALD) on polyethylene naphthalate (PEN) substrates at different temperatures. The fabricated films are then plasma treated with C3F8 to enhance their hydrophobicity. Hydrophobic Al2O3 thin films have shown good morphological and optical properties. Low average arithmetic roughness (Ra) of 1.90 nm, 0.93 nm and 0.88 nm have been recorded for the C3F8 plasma treated films deposited at room temperature (RT), 50 °C and 150 °C, respectively. Optical transmittance of more than 90% has been achieved for the C3F8 plasma treated films grown at 50 °C and 150 °C. The contact angle has been increased from 48° ± 3 to 158° ± 3 for the films deposited at RT and increased from 41° ± 3 to 148° ± 3 for the films deposited at 150 °C.

  17. Gravimetrical and chemical characterization of SiO x structures deposited on fine powders by short plasma exposure in a plasma down stream reactor

    NASA Astrophysics Data System (ADS)

    Spillmann, Adrian; Sonnenfeld, Axel; Rudolf von Rohr, Philipp

    2008-12-01

    The surface of lactose particles was modified by a plasma-enhanced chemical vapor deposition process to improve the flow behavior of the powder. For this, the particulates were treated in a plasma down stream reactor which provides a short (50 ms) and homogeneous exposure to the capacitively coupled RF discharge. The organosilicon monomer hexamethyldisiloxane (HMDSO) was used as a precursor for the formation of SiO x which is deposited on the substrate particle surface. For varying process gas mixtures (O 2/Ar/HMDSO) and RF power applied, the amount of the deposited material was determined gravimetrically after dissolution of the lactose substrate particles and the chemical composition of the accumulated deposition material was investigated by means of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. The concentration of the deposited SiO x relating to the substrate material was found to be in the range of 0.1 wt.%. Based on the ATR-FTIR analysis, the inorganic, i.e. oxidic SiO x fraction of the obtained deposits was shown to be controllable by varying the process parameters, whilst a relatively large amount of organic structures must be considered.

  18. Hybrid layers deposited by an atmospheric pressure plasma process for corrosion protection of galvanized steel.

    PubMed

    Del Frari, D; Bour, J; Bardon, J; Buchheit, O; Arnoult, C; Ruch, D

    2010-04-01

    Finding alternative treatments to reproduce anticorrosion properties of chromated coatings is challenging since both physical barrier and self-healing effects are needed. Siloxane based treatments are known to be a promising way to achieve physical barrier coatings, mainly plasma polymerized hexamethyldisiloxane (ppHMDSO). In addition, it is known that cerium-based coatings can also provide corrosion protection of metals by means of self-healing effect. In this frame, innovative nanoAlCeO3/ppHMDSO layers have thus been deposited and studied. These combinations allow to afford a good physical barrier effect and active properties. Liquid siloxane and cerium-based particles mixture is atomized and introduced as precursors into a carrier gas. Gas mixture is then injected into an atmospheric pressure dielectric barrier discharge (DBD) where plasma polymerization of the siloxane precursor occurs. The influence of cerium concentration on the coating properties is investigated: coating structure and topography have been studied by scanning electron microscopy (SEM) and interferometry, and corrosion resistance of these different coatings is compared by electrochemistry techniques: polarization curves and electrochemical impedance spectroscopy (EIS). Potential self-healing property afforded by cerium in the layer was studied by associating EIS measurements and nanoscratch controlled damaging. Among the different combinations investigated, mixing of plasma polymerized HMDSO and AICeO3 nanoparticles seems to give promising results with a good physical barrier and interesting electroactive properties. Indeed, corrosion currents measured on such coatings are almost as low as those measured with the chromated film. Combination of nanoscratch damaging of layers with EIS experiments to investigate self-healing also allow to measure the active protection property of such layers.

  19. Metalorganic precursor decomposition and oxidation mechanisms in plasma-enhanced ZrO2 deposition

    NASA Astrophysics Data System (ADS)

    Cho, Byeong-Ok; Wang, Jianjun; Chang, Jane P.

    2002-10-01

    We investigated the gas phase reaction mechanisms in the ZrO2-deposition plasma using zirconium tert-butoxide (ZTB) as a metalorganic precursor, Ar as a carrier of the ZTB vapor, and O2 as an oxidant using quadrupole mass spectrometry (QMS). Zirconium containing ions including Zr+, ZrO+, ZrO2H+, ZrO3H3+, and ZrO4H5+ were clearly observed in the plasma, and ions of higher zirconium oxidation states become progressively favored at higher O2-to-ZTB carrying Ar flow rate ratio (O2/Ar), increased chamber pressure, and decreased microwave power. The average oxidation state calculated from the partition of ZrOxHy+ varied from 0.5 to 2.1 in the process range covering O2/Ar of 0 to 4, pressure of 5 to 40 mTorr, and power of 150 to 700 W. Based on the QMS analyses, we proposed two main opposing reaction paths responsible for the complex gas phase reactions, i.e., serial dissociations and serial oxidations. The increase in the electron temperature and density resulted in the shift of ZrOxHy+ to lower oxidation states by enhancing the dissociation of Zr-O bond and by depleting oxygen through gas phase reactions. The repartitioning of the ZrOxHy+ species was also contributed by their different Zr-O dissociation energies. To ascertain the effect of various process variables, we monitored the time evolutions of O2+ and ZrOxHy+ intensities as we abruptly change a process variable: the chemical effect (O2/Ar) led to gradual changes in their intensities, whereas physical effects (pressure and power) caused an abrupt step change in accordance with an instant response of the plasma electrons.

  20. Ultra-Smooth Nanostructured Diamond Films Deposited from He/H2/CH4/N2 Microwave Plasmas

    PubMed Central

    Konovalov, Valery V.; Melo, Andrew; Catledge, Shane A.; Chowdhury, Shafiul

    2008-01-01

    Addition of He to a high CH4 content (10.7 vol%) H2/CH4/N2 feedgas mixture for microwave plasma chemical vapor deposition produced hard (56–72 GPa), ultra-smooth nanostructured diamond films on Ti-6Al-4V alloy substrates. Upon increase in He content up to 71 vol%, root mean squared (RMS) surface roughness of the film decreased to 9–10 nm and average diamond grain size to 5–6 nm. Our studies show that increased nanocrystallinity with He addition in plasma is related to plasma dilution, enhanced fragmentation of carbon containing species, and enhanced formation of CN radical. PMID:16573106