Thin Film Materials and Devices for Resistive Temperature Sensing Applications

DTIC Science & Technology

2015-05-21

materials are metals, their alloys, semiconducting materials, and thermistor materials such as spinels of manganese, cobalt and nickel oxides. 16 10...improved by doping of the thin films to increase the available carriers for transport. In the case of SiGe:H thin films, Ajmera et al. and Saint John et al...Conference, Freiburg, Fed. Rep. of Germany, 1989. [55] M. Stutzmann, J. Stuke and H. Dersch, "Electron Spin Resonance of Doped Glow-discharge

NREL Opens Large Database of Inorganic Thin-Film Materials | News | NREL

Science.gov Websites

Inorganic Thin-Film Materials April 3, 2018 An extensive experimental database of inorganic thin-film Energy Laboratory (NREL) is now publicly available. The High Throughput Experimental Materials (HTEM Schroeder / NREL) "All existing experimental databases either contain many entries or have all this

Supercritical fluid molecular spray thin films and fine powders

DOEpatents

Smith, Richard D.

1988-01-01

Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. The solvent is vaporized and pumped away. Solution pressure is varied to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solution temperature is varied in relation to formation of a two-phase system during expansion to control porosity of the film or powder. A wide variety of film textures and powder shapes are produced of both organic and inorganic compounds. Films are produced with regular textural feature dimensions of 1.0-2.0 .mu.m down to a range of 0.01 to 0.1 .mu.m. Powders are formed in very narrow size distributions, with average sizes in the range of 0.02 to 5 .mu.m.

Formation of ferromagnetic molecular thin films from blends by annealing

PubMed Central

Robaschik, Peter; Ma, Ye; Din, Salahud

2017-01-01

We report on a new approach for the fabrication of ferromagnetic molecular thin films. Co-evaporated films of manganese phthalocyanine (MnPc) and tetracyanoquinodimethane (TCNQ) have been produced by organic molecular beam deposition (OMBD) on rigid (glass, silicon) and flexible (Kapton) substrates kept at room temperature. The MnPc:TCNQ films are found to be entirely amorphous due to the size mismatch of the molecules. However, by annealing while covering the samples highly crystalline MnPc films in the β-polymorph can be obtained at 60 °C lower than when starting with pure MnPc films. The resulting films exhibit substantial coercivity (13 mT) at 2 K and a Curie temperature of 11.5 K. PMID:28900600

Low-voltage electron microscopy of polymer and organic molecular thin films.

PubMed

Drummy, Lawrence F; Yang, Junyan; Martin, David C

2004-06-01

We have demonstrated the capabilities of a novel low-voltage electron microscope (LVEM) for imaging polymer and organic molecular thin films. The LVEM can operate in transmission electron microscopy, scanning transmission electron microscopy, scanning electron microscopy, and electron diffraction modes. The microscope operates at a nominal accelerating voltage of 5 kV and fits on a tabletop. A detailed discussion of the electron-sample interaction processes is presented, and the mean free path for total electron scattering was calculated to be 15 nm for organic samples at 5 kV. The total end point dose for the destruction of crystallinity at 5 kV was estimated at 5 x 10(-4) and 3.5 x 10(-2) C/cm2 for polyethylene and pentacene, respectively. These values are significantly lower than those measured at voltages greater than 100 kV. A defocus series of colloidal gold particles allowed us to estimate the experimental contrast transfer function of the microscope. Images taken of several organic materials have shown high contrast for low atomic number elements and a resolution of 2.5 nm. The materials studied here include thin films of the organic semiconductor pentacene, triblock copolymer films, single-molecule dendrimers, electrospun polymer fibers and gold nanoparticles. Copyright 2004 Elsevier B.V.

Development of Thin Film Thermocouples on Ceramic Materials for Advanced Propulsion System Applications

NASA Technical Reports Server (NTRS)

Holanda, R.

1992-01-01

Thin film thermocouples have been developed for use on metal parts in jet engines to 1000 c. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose of this work is to develop thin film thermocouples for use on ceramic materials. The new thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials tested are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high heating rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hours or more up to temperature of 1500 C depending on the stability of the particular ceramic substrate.

Development of thin film thermocouples on ceramic materials for advanced propulsion system applications

NASA Technical Reports Server (NTRS)

Holanda, Raymond

1993-01-01

Thin film thermocouples were developed for use on metal parts in jet engines to 1000 C. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose is to develop thin film thermocouples for use on ceramic materials. The new thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials tested are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high heating rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hr or more up to temperatures of 1500 C depending on the stability of the particular ceramic substrate.

NMR characterization of thin films

DOEpatents

Gerald II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

2010-06-15

A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

NMR characterization of thin films

DOEpatents

Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

2008-11-25

A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, III, Jerome J.; Halpern, Bret L.

1993-01-01

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures.

Microwave plasma assisted supersonic gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J. III; Halpern, B.L.

1993-10-26

An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures. 5 figures.

Thin film thermocouples for thermoelectric characterization of nanostructured materials

NASA Astrophysics Data System (ADS)

Grayson, Matthew; Zhou, Chuanle; Varrenti, Andrew; Chyung, Seung Hye; Long, Jieyi; Memik, Seda

2011-03-01

The increased use of nanostructured materials as thermoelectrics requires reliable and accurate characterization of the anisotropic thermal coefficients of small structures, such as superlattices and quantum wire networks. Thin evaporated metal films can be used to create thermocouples with a very small thermal mass and low thermal conductivity, in order to measure thermal gradients on nanostructures and thereby measure the thermal conductivity and the Seebeck coefficient of the nanostructure. In this work we confirm the known result that thin metal films have lower Seebeck coefficients than bulk metals, and we also calibrate the Seebeck coefficient of a thin-film Ni/Cr thermocouple with 50 nm thickness, showing it to have about 1/4 the bulk value. We demonstrate reproducibility of this thin-filmSeebeck coefficient on multiple substrates, and we show that this coefficient does, in fact, change as a function of film thickness. We will discuss prototype measurement designs and preliminary work as to how these thin films can be used to study both Seebeck coefficients and thermal conductivities of superlattices in various geometries. The same technology can in principle be used on integrated circuits for thermal mapping, under the name ``Integrated On-Chip Thermocouple Array'' (IOTA).

Research progress of VO2 thin film as laser protecting material

NASA Astrophysics Data System (ADS)

Liu, Zhiwei; Lu, Yuan; Hou, Dianxin

2018-03-01

With the development of laser technology, the battlefield threat of directional laser weapons is becoming more and more serious. The blinding and destruction caused by laser weapons on the photoelectric equipment is an important part of the current photo-electronic warfare. The research on the defense technology of directional laser weapons based on the phase transition characteristics of VO2 thin films is an important subject. The researches of VO2 thin films are summarized based on review these points: the preparation methods of VO2 thin films, phase transition mechanism, phase transition temperature regulating, interaction between VO2 thin films and laser, and the application prospect of vo2 thin film as laser protecting material. This paper has some guiding significance for further research on the VO2 thin films in the field of defense directional laser weapons.

Liquid crystals for organic thin-film transistors

NASA Astrophysics Data System (ADS)

Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-Ichi

2015-04-01

Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10), for FETs and synthesize it. This material provides uniform and molecularly flat polycrystalline thin films reproducibly when SmE precursor thin films are crystallized, and also exhibits high durability of films up to 200 °C. In addition, the mobility of FETs is dramatically enhanced by about one order of magnitude (over 10 cm2 V-1 s-1) after thermal annealing at 120 °C in bottom-gate-bottom-contact FETs. We anticipate the use of SmE liquid crystals in solution-processed FETs may help overcome upcoming difficulties with novel technologies for printed electronics.

Organic and inorganic–organic thin film structures by molecular layer deposition: A review

PubMed Central

Sundberg, Pia

2014-01-01

Summary The possibility to deposit purely organic and hybrid inorganic–organic materials in a way parallel to the state-of-the-art gas-phase deposition method of inorganic thin films, i.e., atomic layer deposition (ALD), is currently experiencing a strongly growing interest. Like ALD in case of the inorganics, the emerging molecular layer deposition (MLD) technique for organic constituents can be employed to fabricate high-quality thin films and coatings with thickness and composition control on the molecular scale, even on complex three-dimensional structures. Moreover, by combining the two techniques, ALD and MLD, fundamentally new types of inorganic–organic hybrid materials can be produced. In this review article, we first describe the basic concepts regarding the MLD and ALD/MLD processes, followed by a comprehensive review of the various precursors and precursor pairs so far employed in these processes. Finally, we discuss the first proof-of-concept experiments in which the newly developed MLD and ALD/MLD processes are exploited to fabricate novel multilayer and nanostructure architectures by combining different inorganic, organic and hybrid material layers into on-demand designed mixtures, superlattices and nanolaminates, and employing new innovative nanotemplates or post-deposition treatments to, e.g., selectively decompose parts of the structure. Such layer-engineered and/or nanostructured hybrid materials with exciting combinations of functional properties hold great promise for high-end technological applications. PMID:25161845

Electrical and optical properties of C46H22N8O4KM (M=Co, Fe, Pb) molecular-material thin films prepared by the vacuum thermal evaporation technique.

PubMed

Sánchez-Vergara, M E; Ruiz Farfán, M A; Alvarez, J R; Ponce Pedraza, A; Ortiz, A; Alvarez Toledano, C

2007-03-01

In this work, the synthesis of new materials formed from metallic phthalocyanines (Pcs) and double potassium salt from 1,8-dihydroxianthraquinone is reported. The newly synthesized materials were characterized by scanning electron microscope (SEM), atomic force microscopy (AFM), infrared (IR) and Ultraviolet-visible (UV-vis) spectroscopy. The powder and thin-film samples of the synthesized materials, deposited by vacuum thermal evaporation, show the same intra-molecular bonds as in the IR spectroscopy studies, which suggests that the thermal evaporation process does not alter these bonds. The effect of temperature on conductivity and electrical conduction mechanism was measured in the thin films (approximately 137 nm thickness). They showed a semiconductor-like behaviour with an optical activation energy arising from indirect transitions of 2.15, 2.13 and 3.6eV for the C(46)H(22)N(8)O(4)KFe, C(46)H(22)N(8)O(4)KPb and C(46)H(22)N(8)O(4)KCo thin films.

Probing molecular orientations in thin films by x-ray photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Li, Y.; Li, P.; Lu, Z.-H.

2018-03-01

A great number of functional organic molecules in active thin-film layers of optoelectronic devices have highly asymmetric structures, such as plate-like, rod-like, etc. This makes molecular orientation an important aspect in thin-films as it can significantly affect both the optical and electrical performance of optoelectronic devices. With a combination of in-situ ultra violet photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS) investigations for organic molecules having a broad range of structural properties, we discovered a rigid connection of core levels and frontier highest occupied molecular orbital levels at organic interfaces. This finding opens up opportunities of using X-ray photoemission spectroscopy as an alternative tool to UPS for providing an easy and unambiguous data interpretation in probing molecular orientations.

Thin film materials and devices for resistive temperature sensing applications

NASA Astrophysics Data System (ADS)

Basantani, Hitesh A.

Thin films of vanadium oxide (VOx) and hydrogenated amorphous silicon (a-Si:H) are the two dominant material systems used in resistive infrared radiation detectors (microbolometers) for sensing long wave infrared (LWIR) wavelengths in the 8--14 microm range. Typical thin films of VO x (x < 2) currently used in the bolometer industry have a magnitude of temperature coefficient of resistance (TCR) between 2%/K -- 3%/K. In contrast, thin films of hydrogenated germanium (SiGe:H) have |TCR| between 3%/K to 4%/K. Devices made from either of these materials have resulted in similar device performance with NETD ≈ 25 mK. The performance of the microbolometers is limited by the electronic noise, especially 1/f noise. Therefore, regardless of the choice of bolometer sensing material and read out circuitry, manufacturers are constantly striving to reduce 1/f noise while simultaneously increasing TCR to give better signal to noise ratios in their bolometers and ultimately, better image quality with more thermal information to the end user. In this work, thin films of VOx and hydrogenated germanium (Ge:H), having TCR values > 4 %/K are investigated as potential candidates for higher sensitivity next generation of microbolometers. Thin films of VO x were deposited by Biased Target Ion Beam Deposition (BTIBD) (˜85 nm thick). Electrical characterization of lateral resistor structures showed resistivity ranging from 104 O--cm to 2.1 x 104 O--cm, TCR varying from --4%/K to --5%/K, normalized Hooge parameter (alphaH/n) of 5 x 10 -21 to 5 x 10-18 cm3. Thin films of Ge:H were deposited by plasma enhanced chemical vapor deposition (PECVD) by incorporating an increasing amount of crystal fraction in the growing thin films. Thin films of Ge:H having a mixed phase, amorphous + nanocrystalline, having a |TCR| > 6 %/K were deposited with resistivity < 2,300 O--cm and a normalized Hooge's parameter 'alphaH/n' < 2 x 10-20 cm3. Higher TCR materials are desired, however, such materials have

Rupture mechanism of liquid crystal thin films realized by large-scale molecular simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Trung D; Carrillo, Jan-Michael Y; Brown, W Michael

2014-01-01

The ability of liquid crystal (LC) molecules to respond to changes in their environment makes them an interesting candidate for thin film applications, particularly in bio-sensing, bio-mimicking devices, and optics. Yet the understanding of the (in)stability of this family of thin films has been limited by the inherent challenges encountered by experiment and continuum models. Using unprecedented largescale molecular dynamics (MD) simulations, we address the rupture origin of LC thin films wetting a solid substrate at length scales similar to those in experiment. Our simulations show the key signatures of spinodal instability in isotropic and nematic films on top ofmore » thermal nucleation, and importantly, for the first time, evidence of a common rupture mechanism independent of initial thickness and LC orientational ordering. We further demonstrate that the primary driving force for rupture is closely related to the tendency of the LC mesogens to recover their local environment in the bulk state. Our study not only provides new insights into the rupture mechanism of liquid crystal films, but also sets the stage for future investigations of thin film systems using peta-scale molecular dynamics simulations.« less

Thin film mechanics

NASA Astrophysics Data System (ADS)

Cooper, Ryan C.

This doctoral thesis details the methods of determining mechanical properties of two classes of novel thin films suspended two-dimensional crystals and electron beam irradiated microfilms of polydimethylsiloxane (PDMS). Thin films are used in a variety of surface coatings to alter the opto-electronic properties or increase the wear or corrosion resistance and are ideal for micro- and nanoelectromechanical system fabrication. One of the challenges in fabricating thin films is the introduction of strains which can arise due to application techniques, geometrical conformation, or other spurious conditions. Chapters 2-4 focus on two dimensional materials. This is the intrinsic limit of thin films-being constrained to one atomic or molecular unit of thickness. These materials have mechanical, electrical, and optical properties ideal for micro- and nanoelectromechanical systems with truly novel device functionality. As such, the breadth of applications that can benefit from a treatise on two dimensional film mechanics is reason enough for exploration. This study explores the anomylously high strength of two dimensional materials. Furthermore, this work also aims to bridge four main gaps in the understanding of material science: bridging the gap between ab initio calculations and finite element analysis, bridging the gap between ab initio calculations and experimental results, nanoscale to microscale, and microscale to mesoscale. A nonlinear elasticity model is used to determine the necessary elastic constants to define the strain-energy density function for finite strain. Then, ab initio calculations-density functional theory-is used to calculate the nonlinear elastic response. Chapter 2 focuses on validating this methodology with atomic force microscope nanoindentation on molybdenum disulfide. Chapter 3 explores the convergence criteria of three density functional theory solvers to further verify the numerical calculations. Chapter 4 then uses this model to investigate

Structured Ionomer Thin Films at Water Interface: Molecular Dynamics Simulation Insight

DOE PAGES

Aryal, Dipak; Agrawal, Anupriya; Perahia, Dvora; ...

2017-08-23

Controlling the structure and dynamics of thin films of ionizable polymers at water interfaces is critical to their many applications. As the chemical diversity within one polymer is increased, controlling the structure and dynamics of the polymer, which is a key to their use, becomes a challenge. Here molecular dynamics simulations (MD) are used to obtain molecular insight into the structure and dynamics of thin films of one such macromolecule at the interface with water. The polymer consists of an ABCBA topology with randomly sulfonated polystyrene (C), tethered symmetrically to flexible poly(ethylene- r-propylene) blocks (B), and end-capped by a poly(more » t-butylstyrene) block (A). The compositions of the interfacial and bulk regions of thin films of the ABCBA polymers are followed as a function of exposure time to water. We find that interfacial rearrangements take place where buried ionic segments migrate toward the water interface. The hydrophobic blocks collapse and rearrange to minimize their exposure to water. In conclusion, the water that initially drives interfacial reengagements breaks the ionic clusters within the film, forming a dynamic hydrophilic internal network within the hydrophobic segments.« less

Evaporation system and method for gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J.; Halpern, B.L.

1994-10-18

A method and apparatus are disclosed for depositing thin films of materials such as metals, oxides and nitrides at low temperature relies on a supersonic free jet of inert carrier gas to transport vapor species generated from an evaporation source to the surface of a substrate. Film deposition vapors are generated from solid film precursor materials, including those in the form of wires or powders. The vapor from these sources is carried downstream in a low pressure supersonic jet of inert gas to the surface of a substrate where the vapors deposit to form a thin film. A reactant gas can be introduced into the gas jet to form a reaction product with the evaporated material. The substrate can be moved from the gas jet past a gas jet containing a reactant gas in which a discharge has been generated, the speed of movement being sufficient to form a thin film which is chemically composed of the evaporated material and reactant gases. 8 figs.

Evaporation system and method for gas jet deposition of thin film materials

DOEpatents

Schmitt, Jerome J.; Halpern, Bret L.

1994-01-01

A method and apparatus for depositing thin films of materials such as metals, oxides and nitrides at low temperature relies on a supersonic free jet of inert carrier gas to transport vapor species generated from an evaporation source to the surface of a substrate. Film deposition vapors are generated from solid film precursor materials, including those in the form of wires or powders. The vapor from these sources is carried downstream in a low pressure supersonic jet of inert gas to the surface of a substrate where the vapors deposit to form a thin film. A reactant gas can be introduced into the gas jet to form a reaction product with the evaporated material. The substrate can be moved from the gas jet past a gas jet containing a reactant gas in which a discharge has been generated, the speed of movement being sufficient to form a thin film which is chemically composed of the evaporated material and reactant gases.

Liquid crystals for organic thin-film transistors

PubMed Central

Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-ichi

2015-01-01

Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10), for FETs and synthesize it. This material provides uniform and molecularly flat polycrystalline thin films reproducibly when SmE precursor thin films are crystallized, and also exhibits high durability of films up to 200 °C. In addition, the mobility of FETs is dramatically enhanced by about one order of magnitude (over 10 cm2 V−1 s−1) after thermal annealing at 120 °C in bottom-gate-bottom-contact FETs. We anticipate the use of SmE liquid crystals in solution-processed FETs may help overcome upcoming difficulties with novel technologies for printed electronics. PMID:25857435

Liquid crystals for organic thin-film transistors.

PubMed

Iino, Hiroaki; Usui, Takayuki; Hanna, Jun-ichi

2015-04-10

Crystalline thin films of organic semiconductors are a good candidate for field effect transistor (FET) materials in printed electronics. However, there are currently two main problems, which are associated with inhomogeneity and poor thermal durability of these films. Here we report that liquid crystalline materials exhibiting a highly ordered liquid crystal phase of smectic E (SmE) can solve both these problems. We design a SmE liquid crystalline material, 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10), for FETs and synthesize it. This material provides uniform and molecularly flat polycrystalline thin films reproducibly when SmE precursor thin films are crystallized, and also exhibits high durability of films up to 200 °C. In addition, the mobility of FETs is dramatically enhanced by about one order of magnitude (over 10 cm(2) V(-1) s(-1)) after thermal annealing at 120 °C in bottom-gate-bottom-contact FETs. We anticipate the use of SmE liquid crystals in solution-processed FETs may help overcome upcoming difficulties with novel technologies for printed electronics.

The effect of solvent upon molecularly thin rotaxane film formation

NASA Astrophysics Data System (ADS)

Farrell, Alan A.; Kay, Euan R.; Bottari, Giovanni; Leigh, David A.; Jarvis, Suzanne P.

2007-05-01

We have investigated variations in molecularly thin rotaxane films deposited by solvent evaporation, using atomic force microscopy (AFM). Small changes in rotaxane structure result in significant differences in film morphology. The addition of exo-pyridyl moietes to the rotaxane macrocycle results in uniform domains having orientations corresponding to the underlying substrate lattice, while a larger, less symmetric molecule results in a greater lattice mismatch and smaller domain sizes. We have measured differences in film heights both as a function of the solvent of deposition and as a function of surface coverage of rotaxanes. Based on these observations we describe how the use of solvents with higher hydrogen-bond basicity results in films which are more likely to favour sub-molecular motion.

Synthesis, characterization, and pulsed laser ablation of molecular sieves for thin film applications

NASA Astrophysics Data System (ADS)

Munoz, Trinidad, Jr.

1998-12-01

Molecular sieves are one class of crystalline low density metal oxides which are made up of one-, two-, and three dimensional pores and/or cages. We have investigated the synthesis and characterization of metal substituted aluminophosphates and all silica molecular sieves for thin film applications. A new copper substituted aluminophosphate, CuAPO-5 has been synthesized and characterized using x-ray powder diffraction, FT-IR spectroscopy and scanning electron microscopy. Electron spin resonance and electron spin echo modulation provided supporting evidence of framework incorporation of Cu(II) ions. Thus, an exciting addition has been added to the family of metal substituted aluminophosphates where substitution of the metal has been demonstrated as framework species. Also presented here is the synthesis and characterization of an iron substituted aluminophosphate, FeAPO-5, and an all silica zeolite, UTD-1 for thin film applications. Pulsed laser ablation has been employed as the technique to generate thin films. Here an excimer laser (KrFsp*, 248 nm) was used to deposit the molecular sieves on a variety of substrates including polished silicon, titanium nitride, and porous stainless steel disks. The crystallinity of the deposited films was enhanced by a post hydrothermal treatment. A vapor phase treatment of the laser deposited FeAPO-5 films has been shown to increase the crystallinity of the film without increasing film thickness. Thin films of the FeAPO-5 molecular sieves were subsequently used as the dielectric phase in capacitive type chemical sensors. The capacitance change of the FeAPO-5 devices to the relative moisture makes them potential humidity sensors. The all silica zeolite UTD-1 thin films were deposited on polished silicon and porous supports. A brief post hydrothermal treatment of the laser deposited films deposited on polished silicon and porous metal supports resulted in oriented film growth lending these films to applications in gas separations

Permanent laser conditioning of thin film optical materials

DOEpatents

Wolfe, C. Robert; Kozlowski, Mark R.; Campbell, John H.; Staggs, Michael; Rainer, Frank

1995-01-01

The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold.

Permanent laser conditioning of thin film optical materials

DOEpatents

Wolfe, C.R.; Kozlowski, M.R.; Campbell, J.H.; Staggs, M.; Rainer, F.

1995-12-05

The invention comprises a method for producing optical thin films with a high laser damage threshold and the resulting thin films. The laser damage threshold of the thin films is permanently increased by irradiating the thin films with a fluence below an unconditioned laser damage threshold. 9 figs.

Quinuclidinium salt ferroelectric thin-film with duodecuple-rotational polarization-directions

NASA Astrophysics Data System (ADS)

You, Yu-Meng; Tang, Yuan-Yuan; Li, Peng-Fei; Zhang, Han-Yue; Zhang, Wan-Ying; Zhang, Yi; Ye, Heng-Yun; Nakamura, Takayoshi; Xiong, Ren-Gen

2017-04-01

Ferroelectric thin-films are highly desirable for their applications on energy conversion, data storage and so on. Molecular ferroelectrics had been expected to be a better candidate compared to conventional ferroelectric ceramics, due to its simple and low-cost film-processability. However, most molecular ferroelectrics are mono-polar-axial, and the polar axes of the entire thin-film must be well oriented to a specific direction to realize the macroscopic ferroelectricity. To align the polar axes, an orientation-controlled single-crystalline thin-film growth method must be employed, which is complicated, high-cost and is extremely substrate-dependent. In this work, we discover a new molecular ferroelectric of quinuclidinium periodate, which possesses six-fold rotational polar axes. The multi-axes nature allows the thin-film of quinuclidinium periodate to be simply prepared on various substrates including flexible polymer, transparent glasses and amorphous metal plates, without considering the crystallinity and crystal orientation. With those benefits and excellent ferroelectric properties, quinuclidinium periodate shows great potential in applications like wearable devices, flexible materials, bio-machines and so on.

Spray Chemical Vapor Deposition of Single-Source Precursors for Chalcopyrite I-III-VI2 Thin-Film Materials

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Banger, Kulbinder K.; Jin, Michael H.-C.; Harris, Jerry D.; McNatt, Jeremiah S.; Dickman, John E.

2008-01-01

Thin-film solar cells on flexible, lightweight, space-qualified substrates provide an attractive approach to fabricating solar arrays with high mass-specific power. A polycrystalline chalcopyrite absorber layer is among the new generation of photovoltaic device technologies for thin film solar cells. At NASA Glenn Research Center we have focused on the development of new single-source precursors (SSPs) for deposition of semiconducting chalcopyrite materials onto lightweight, flexible substrates. We describe the syntheses and thermal modulation of SSPs via molecular engineering. Copper indium disulfide and related thin-film materials were deposited via aerosol-assisted chemical vapor deposition using SSPs. Processing and post-processing parameters were varied in order to modify morphology, stoichiometry, crystallography, electrical properties, and optical properties to optimize device quality. Growth at atmospheric pressure in a horizontal hotwall reactor at 395 C yielded the best device films. Placing the susceptor closer to the evaporation zone and flowing a more precursor-rich carrier gas through the reactor yielded shinier-, smoother-, and denser-looking films. Growth of (112)-oriented films yielded more Cu-rich films with fewer secondary phases than growth of (204)/(220)-oriented films. Post-deposition sulfur-vapor annealing enhanced stoichiometry and crystallinity of the films. Photoluminescence studies revealed four major emission bands and a broad band associated with deep defects. The highest device efficiency for an aerosol-assisted chemical vapor deposited cell was one percent.

Chalcogenide phase-change thin films used as grayscale photolithography materials.

PubMed

Wang, Rui; Wei, Jingsong; Fan, Yongtao

2014-03-10

Chalcogenide phase-change thin films are used in many fields, such as optical information storage and solid-state memory. In this work, we present another application of chalcogenide phase-change thin films, i.e., as grayscale photolithgraphy materials. The grayscale patterns can be directly inscribed on the chalcogenide phase-change thin films by a single process through direct laser writing method. In grayscale photolithography, the laser pulse can induce the formation of bump structure, and the bump height and size can be precisely controlled by changing laser energy. Bumps with different height and size present different optical reflection and transmission spectra, leading to the different gray levels. For example, the continuous-tone grayscale images of lifelike bird and cat are successfully inscribed onto Sb(2)Te(3) chalcogenide phase-change thin films using a home-built laser direct writer, where the expression and appearance of the lifelike bird and cat are fully presented. This work provides a way to fabricate complicated grayscale patterns using laser-induced bump structures onto chalcogenide phase-change thin films, different from current techniques such as photolithography, electron beam lithography, and focused ion beam lithography. The ability to form grayscale patterns of chalcogenide phase-change thin films reveals many potential applications in high-resolution optical images for micro/nano image storage, microartworks, and grayscale photomasks.

Multiferroic fluoride BaCoF4 Thin Films Grown Via Molecular Beam Epitaxy

NASA Astrophysics Data System (ADS)

Borisov, Pavel; Johnson, Trent; García-Castro, Camilo; Kc, Amit; Schrecongost, Dustin; Cen, Cheng; Romero, Aldo; Lederman, David

Multiferroic materials exhibit exciting physics related to the simultaneous presence of multiple long-range orders, in many cases consisting of antiferromagnetic (AF) and ferroelectric (FE) orderings. In order to provide a new, promising route for fluoride-based multiferroic material engineering, we grew multiferroic fluoride BaCoF4 in thin film form on Al2O3 (0001) substrates by molecular beam epitaxy. The films grow with the orthorhombic b-axis out-of-plane and with three in-plane structural twin domains along the polar c-axis directions. The FE ordering in thin films was verified by FE remanent hysteresis loops measurements at T = 14 K and by room temperature piezoresponse force microscopy (PFM). An AF behavior was found below Neel temperature TN ~ 80 K, which is in agreement with the bulk properties. At lower temperatures two additional magnetic phase transitions at 19 K and 41 K were found. First-principles calculations demonstrated that the growth strain applied to the bulk BaCoF4 indeed favors two canted spin orders, along the b- and a-axes, respectively, in addition to the main AF spin order along the c-axis. Supported by FAME (Contract 2013-MA-2382), WV Research Challenge Grant (HEPC.dsr.12.29), and DMREF-NSF 1434897.

High quality atomically thin PtSe2 films grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Yan, Mingzhe; Wang, Eryin; Zhou, Xue; Zhang, Guangqi; Zhang, Hongyun; Zhang, Kenan; Yao, Wei; Lu, Nianpeng; Yang, Shuzhen; Wu, Shilong; Yoshikawa, Tomoki; Miyamoto, Koji; Okuda, Taichi; Wu, Yang; Yu, Pu; Duan, Wenhui; Zhou, Shuyun

2017-12-01

Atomically thin PtSe2 films have attracted extensive research interests for potential applications in high-speed electronics, spintronics and photodetectors. Obtaining high quality thin films with large size and controlled thickness is critical. Here we report the first successful epitaxial growth of high quality PtSe2 films by molecular beam epitaxy. Atomically thin films from 1 ML to 22 ML have been grown and characterized by low-energy electron diffraction, Raman spectroscopy and x-ray photoemission spectroscopy. Moreover, a systematic thickness dependent study of the electronic structure is revealed by angle-resolved photoemission spectroscopy (ARPES), and helical spin texture is revealed by spin-ARPES. Our work provides new opportunities for growing large size single crystalline films to investigate the physical properties and potential applications of PtSe2.

Thin-Film Material Science and Processing | Materials Science | NREL

Science.gov Websites

, a prime example of this research is thin-film photovoltaics (PV). Thin films are important because have developed a quantitative high-throughput technique that can measure many barriers in parallel with

Effect of substrates on the molecular orientation of silicon phthalocyanine dichloride thin films

NASA Astrophysics Data System (ADS)

Deng, Juzhi; Baba, Yuji; Sekiguchi, Tetsuhiro; Hirao, Norie; Honda, Mitsunori

2007-05-01

Molecular orientations of silicon phthalocyanine dichloride (SiPcCl2) thin films deposited on three different substrates have been measured by near-edge x-ray absorption fine structure (NEXAFS) spectroscopy using linearly polarized synchrotron radiation. The substrates investigated were highly oriented pyrolitic graphite (HOPG), polycrystalline gold and indium tin oxide (ITO). For thin films of about five monolayers, the polarization dependences of the Si K-edge NEXAFS spectra showed that the molecular planes of SiPcCl2 on three substrates were nearly parallel to the surface. Quantitative analyses of the polarization dependences revealed that the tilted angle on HOPG was only 2°, which is interpreted by the perfect flatness of the HOPG surface. On the other hand, the tilted angle on ITO was 26°. Atomic force microscopy (AFM) observation of the ITO surface showed that the periodicity of the horizontal roughness is of the order of a few nanometres, which is larger than the molecular size of SiPcCl2. It is concluded that the morphology of the top surface layer of the substrate affects the molecular orientation of SiPcCl2 molecules not only for mono-layered adsorbates but also for multi-layered thin films.

Defect-Controlled Preparation of UiO-66 Metal-Organic Framework Thin Films with Molecular Sieving Capability.

PubMed

Zhang, Caiqin; Zhao, Yajing; Li, Yali; Zhang, Xuetong; Chi, Lifeng; Lu, Guang

2016-01-01

Metal-organic framework (MOF) UiO-66 thin films are solvothermally grown on conducting substrates. The as-synthesized MOF thin films are subsequently dried by a supercritical process or treated with polydimethylsiloxane (PDMS). The obtained UiO-66 thin films show excellent molecular sieving capability as confirmed by the electrochemical studies for redox-active species with different sizes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemically Deposited Thin-Film Solar Cell Materials

NASA Technical Reports Server (NTRS)

Raffaelle, R.; Junek, W.; Gorse, J.; Thompson, T.; Harris, J.; Hehemann, D.; Hepp, A.; Rybicki, G.

2005-01-01

We have been working on the development of thin film photovoltaic solar cell materials that can be produced entirely by wet chemical methods on low-cost flexible substrates. P-type copper indium diselenide (CIS) absorber layers have been deposited via electrochemical deposition. Similar techniques have also allowed us to incorporate both Ga and S into the CIS structure, in order to increase its optical bandgap. The ability to deposit similar absorber layers with a variety of bandgaps is essential to our efforts to develop a multi-junction thin-film solar cell. Chemical bath deposition methods were used to deposit a cadmium sulfide (CdS) buffer layers on our CIS-based absorber layers. Window contacts were made to these CdS/CIS junctions by the electrodeposition of zinc oxide (ZnO). Structural and elemental determinations of the individual ZnO, CdS and CIS-based films via transmission spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy and energy dispersive spectroscopy will be presented. The electrical characterization of the resulting devices will be discussed.

Thin-film optical initiator

DOEpatents

Erickson, Kenneth L.

2001-01-01

A thin-film optical initiator having an inert, transparent substrate, a reactive thin film, which can be either an explosive or a pyrotechnic, and a reflective thin film. The resultant thin-film optical initiator system also comprises a fiber-optic cable connected to a low-energy laser source, an output charge, and an initiator housing. The reactive thin film, which may contain very thin embedded layers or be a co-deposit of a light-absorbing material such as carbon, absorbs the incident laser light, is volumetrically heated, and explodes against the output charge, imparting about 5 to 20 times more energy than in the incident laser pulse.

Using Organic Light-Emitting Electrochemical Thin-Film Devices to Teach Materials Science

ERIC Educational Resources Information Center

Sevian, Hannah; Muller, Sean; Rudmann, Hartmut; Rubner, Michael F.

2004-01-01

Materials science can be taught by applying organic light-emitting electrochemical thin-film devices and in this method students were allowed to make a light-emitting device by spin coating a thin film containing ruthenium (II) complex ions onto a glass slide. Through this laboratory method students are provided with the opportunity to learn about…

Modeling of metal thin film growth: Linking angstrom-scale molecular dynamics results to micron-scale film topographies

NASA Astrophysics Data System (ADS)

Hansen, U.; Rodgers, S.; Jensen, K. F.

2000-07-01

A general method for modeling ionized physical vapor deposition is presented. As an example, the method is applied to growth of an aluminum film in the presence of an ionized argon flux. Molecular dynamics techniques are used to examine the surface adsorption, reflection, and sputter reactions taking place during ionized physical vapor deposition. We predict their relative probabilities and discuss their dependence on energy and incident angle. Subsequently, we combine the information obtained from molecular dynamics with a line of sight transport model in a two-dimensional feature, incorporating all effects of reemission and resputtering. This provides a complete growth rate model that allows inclusion of energy- and angular-dependent reaction rates. Finally, a level-set approach is used to describe the morphology of the growing film. We thus arrive at a computationally highly efficient and accurate scheme to model the growth of thin films. We demonstrate the capabilities of the model predicting the major differences on Al film topographies between conventional and ionized sputter deposition techniques studying thin film growth under ionized physical vapor deposition conditions with different Ar fluxes.

Iron-Terephthalate Coordination Network Thin Films Through In-Situ Atomic/Molecular Layer Deposition.

PubMed

Tanskanen, A; Karppinen, M

2018-06-12

Iron terephthalate coordination network thin films can be fabricated using the state-of-the-art gas-phase atomic/molecular layer deposition (ALD/MLD) technique in a highly controlled manner. Iron is an Earth-abundant and nonhazardous transition metal, and with its rich variety of potential applications an interesting metal constituent for the inorganic-organic coordination network films. Our work underlines the role of the metal precursor used when aiming at in-situ ALD/MLD growth of crystalline inorganic-organic thin films. We obtain crystalline iron terephthalate films when FeCl 3 is employed as the iron source whereas depositions based on the bulkier Fe(acac) 3 precursor yield amorphous films. The chemical composition and structure of the films are investigated with GIXRD, XRR, FTIR and XPS.

Magnetic properties of low-moment ferrimagnetic Heusler Cr2CoGa thin films grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Jamer, Michelle E.; Sterbinsky, George E.; Stephen, Gregory M.; DeCapua, Matthew C.; Player, Gabriel; Heiman, Don

2016-10-01

Recently, theorists have predicted many materials with a low magnetic moment and large spin-polarization for spintronic applications. These compounds are predicted to form in the inverse Heusler structure; however, many of these compounds have been found to phase segregate. In this study, ordered Cr2CoGa thin films were synthesized without phase segregation using molecular beam epitaxy. The present as-grown films exhibit a low magnetic moment from antiferromagnetically coupled Cr and Co atoms as measured with superconducting quantum interface device magnetometry and soft X-ray magnetic circular dichroism. Electrical measurements demonstrated a thermally-activated semiconductor-like resistivity component with an activation energy of 87 meV. These results confirm spin gapless semiconducting behavior, which makes these thin films well positioned for future devices.

Thin film microelectronics materials production in the vacuum of space

NASA Astrophysics Data System (ADS)

Ignatiev, A.; Sterling, M.; Horton, C.; Freundlich, A.; Pei, S.; Hill, R.

1997-01-01

The international Space Station era will open up a new dimension in the use of one of the unique attributes of space, vacuum, for the production of advanced semiconductor materials and devices for microelectronics applications. Ultra-vacuum is required for the fabrication in thin film form of high quality semiconductors. This can be accomplished behind a free flying platform similar to the current Wake Shield Facility which is specifically designed to support in-space production. The platform will require apparatus for thin film growth, a robotics interface to allow for the change out of raw materials and the harvesting of finished product, and a servicing plant incorporating Space Station that will support long-term utilization of the platform.

Thermoelectric Properties of Nanograined Si-Ge-Au Thin Films Grown by Molecular Beam Deposition

NASA Astrophysics Data System (ADS)

Nishino, Shunsuke; Ekino, Satoshi; Inukai, Manabu; Omprakash, Muthusamy; Adachi, Masahiro; Kiyama, Makoto; Yamamoto, Yoshiyuki; Takeuchi, Tsunehiro

2018-06-01

Conditions to achieve extremely large Seebeck coefficient and extremely small thermal conductivity in Si-Ge-Au thin films formed of nanosized grains precipitated in amorphous matrix have been investigated. We employed molecular beam deposition to prepare Si1- x Ge x Au y thin films on sapphire substrate. The deposited films were annealed under nitrogen gas atmosphere at 300°C to 500°C for 15 min to 30 min. Nanocrystals dispersed in amorphous matrix were clearly observed by transmission electron microscopy. We did not observe anomalously large Seebeck coefficient, but very low thermal conductivity of nearly 1.0 W K-1 m-1 was found at around 0.2 < x < 0.6. The compositional dependence of the thermal conductivity was well accounted for by the compositional dependence of the mixing entropy. Some of these values agree exactly with the amorphous limit predicted by theoretical calculations. The smallest lattice thermal conductivity found for the present samples is lower than that of nanostructured Si-Ge bulk material for which dimensionless figure of merit of ZT ≈ 1 was reported at high temperature.

Thin Film Delamination Using a High Power Pulsed Laser Materials Interaction

NASA Astrophysics Data System (ADS)

Sherman, Bradley

Thin films attached to substrates are only effective while the film is adhered to the substrate. When the film begins to spall the whole system can fail, thus knowing the working strength of the film substrate system is important when designing structures. Surface acoustic waves (SAWs) are suitable for characterization of thin film mechanical properties due to the confinement of their energy within a shallow depth from a material surface. In this project, we study the feasibility of inducing dynamic interfacial failure in thin films using surface waves generated by a high power pulsed laser. Surface acoustic waves are modeled using a finite element numerical code, where the ablative interaction between the pulsed laser and the incident film is modeled using equivalent surface mechanical stresses. The numerical results are validated using experimental results from a laser ultrasonic setup. Once validated the normal film-substrate interfacial stress can be extracted from the numerical code and tends to be in the mega-Pascal range. This study uses pulsed laser generation to produce SAW in various metallic thin film/substrate systems. Each system varies in its response based on its dispersive relationship and as such requires individualized numerical modeling to match the experimental data. In addition to pulsed SAW excitation using an ablative source, a constrained thermo-mechanical load produced by the ablation of a metal film under a polymer layer is explored to generate larger dynamic mechanical stresses. These stresses are sufficient to delaminate the thin film in a manner similar to a peel test. However, since the loading is produced by a pulsed laser source, it occurs at a much faster rate, limiting the influence of slower damage modes that are present in quasi-static loading. This approach is explored to predict the interfacial fracture toughness of weak thin film interfaces.

Simultaneous measurement of thermal conductivity and heat capacity of bulk and thin film materials using frequency-dependent transient thermoreflectance method.

PubMed

Liu, Jun; Zhu, Jie; Tian, Miao; Gu, Xiaokun; Schmidt, Aaron; Yang, Ronggui

2013-03-01

The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nanoscale materials with unknown or less-understood thermal properties, it is either questionable to assume bulk heat capacity for nanostructures or difficult to obtain the bulk form of those materials for a conventional heat capacity measurement. In this paper, we describe a technique for simultaneous measurement of thermal conductivity κ and volumetric heat capacity C of both bulk and thin film materials using frequency-dependent time-domain thermoreflectance (TDTR) signals. The heat transfer model is analyzed first to find how different combinations of κ and C determine the frequency-dependent TDTR signals. Simultaneous measurement of thermal conductivity and volumetric heat capacity is then demonstrated with bulk Si and thin film SiO2 samples using frequency-dependent TDTR measurement. This method is further testified by measuring both thermal conductivity and volumetric heat capacity of novel hybrid organic-inorganic thin films fabricated using the atomic∕molecular layer deposition. Simultaneous measurement of thermal conductivity and heat capacity can significantly shorten the development∕discovery cycle of novel materials.

Epitaxial thin films

DOEpatents

Hunt, Andrew Tye; Deshpande, Girish; Lin, Wen-Yi; Jan, Tzyy-Jiuan

2006-04-25

Epitatial thin films for use as buffer layers for high temperature superconductors, electrolytes in solid oxide fuel cells (SOFC), gas separation membranes or dielectric material in electronic devices, are disclosed. By using CCVD, CACVD or any other suitable deposition process, epitaxial films having pore-free, ideal grain boundaries, and dense structure can be formed. Several different types of materials are disclosed for use as buffer layers in high temperature superconductors. In addition, the use of epitaxial thin films for electrolytes and electrode formation in SOFCs results in densification for pore-free and ideal gain boundary/interface microstructure. Gas separation membranes for the production of oxygen and hydrogen are also disclosed. These semipermeable membranes are formed by high-quality, dense, gas-tight, pinhole free sub-micro scale layers of mixed-conducting oxides on porous ceramic substrates. Epitaxial thin films as dielectric material in capacitors are also taught herein. Capacitors are utilized according to their capacitance values which are dependent on their physical structure and dielectric permittivity. The epitaxial thin films of the current invention form low-loss dielectric layers with extremely high permittivity. This high permittivity allows for the formation of capacitors that can have their capacitance adjusted by applying a DC bias between their electrodes.

High-throughput screening for combinatorial thin-film library of thermoelectric materials.

PubMed

Watanabe, Masaki; Kita, Takuji; Fukumura, Tomoteru; Ohtomo, Akira; Ueno, Kazunori; Kawasaki, Masashi

2008-01-01

A high-throughput method has been developed to evaluate the Seebeck coefficient and electrical resistivity of combinatorial thin-film libraries of thermoelectric materials from room temperature to 673 K. Thin-film samples several millimeters in size were deposited on an integrated Al2O3 substrate with embedded lead wires and local heaters for measurement of the thermopower under a controlled temperature gradient. An infrared camera was used for real-time observation of the temperature difference Delta T between two electrical contacts on the sample to obtain the Seebeck coefficient. The Seebeck coefficient and electrical resistivity of constantan thin films were shown to be almost identical to standard data for bulk constantan. High-throughput screening was demonstrated for a thermoelectric Mg-Si-Ge combinatorial library.

Magnetic properties of low-moment ferrimagnetic Heusler Cr 2CoGa thin films grown by molecular beam epitaxy

DOE PAGES

Jamer, Michelle E.; Sterbinsky, George E.; Stephen, Gregory M.; ...

2016-10-31

Recently, theorists have predicted many materials with a low magnetic moment and large spin-polarization for spintronic applications. These compounds are predicted to form in the inverse Heusler structure; however, many of these compounds have been found to phase segregate. In this study, ordered Cr 2CoGa thin films were synthesized without phase segregation using molecular beam epitaxy. The present as-grown films exhibit a low magnetic moment from antiferromagnetically coupled Cr and Co atoms as measured with superconducting quantum interface device magnetometry and soft X-ray magnetic circular dichroism. Electrical measurements demonstrated a thermally-activated semiconductor-like resistivity component with an activation energy of 87more » meV. Finally, these results confirm spin gapless semiconducting behavior, which makes these thin films well positioned for future devices.« less

Electrodeposition of Metal Matrix Composites and Materials Characterization for Thin-Film Solar Cells

DTIC Science & Technology

2017-12-04

34High-Concentration III-V Multijunction Solar Cells," 2017, <http://www.nrel.gov/ pv /high-concentration-iii-v-multijunction- solar - cells.html>. O. K...AFRL-RV-PS- AFRL-RV-PS- TR-2017-0174 TR-2017-0174 ELECTRODEPOSITION OF METAL MATRIX COMPOSITES AND MATERIALS CHARACTERIZATION FOR THIN-FILM SOLAR ...0242 Electrodeposition of Metal Matrix Composites and Materials Characterization for Thin-Film Solar Cells 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

[Spectral emissivity of thin films].

PubMed

Zhong, D

2001-02-01

In this paper, the contribution of multiple reflections in thin film to the spectral emissivity of thin films of low absorption is discussed. The expression of emissivity of thin films derived here is related to the thin film thickness d and the optical constants n(lambda) and k(lambda). It is shown that in the special case d-->infinity the emissivity of thin films is equivalent to that of the bulk material. Realistic numerical and more precise general numerical results for the dependence of the emissivity on d, n(lambda) and k(lambda) are given.

Gas Permeation in Thin Glassy Polymer Films

NASA Astrophysics Data System (ADS)

Paul, Donald

2011-03-01

The development of asymmetric and composite membranes with very thin dense ``skins'' needed to achieve high gas fluxes enabled the commercial use of membranes for molecular level separations. It has been generally assumed that these thin skins, with thicknesses of the order of 100 nm, have the same permeation characteristics as films with thicknesses of 25 microns or more. Thick films are easily made in the laboratory and have been used extensively for measuring permeation characteristics to evaluate the potential of new polymers for membrane applications. There is now evidence that this assumption can be in very significant error, and use of thick film data to select membrane materials or predict performance should be done with caution. This presentation will summarize our work on preparing films of glassy polymers as thin as 20 nm and characterizing their behavior by gas permeation, ellipsometry and positron annihilation lifetime spectroscopy. Some of the most important polymers used commercially as gas separation membranes, i.e., Matrimid polyimide, polysulfone (PSF) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), have been made into well-defined thin films in our laboratories by spin casting techniques and their properties studied using the techniques we have developed. These thin films densify (or physically age) much faster than thicker films, and, as result, the permeability decreases, sometimes by several-fold over weeks or months for thin films. This means that the properties of these thin films can be very different from bulk films. The techniques, interpretations and implications of these observations will be discussed. In a broader sense, gas permeation measurements can be a powerful way of developing a better understanding of the effects of polymer chain confinement and/or surface mobility on the behavior of thin films.

The Constitutive Modeling of Thin Films with Randon Material Wrinkles

NASA Technical Reports Server (NTRS)

Murphey, Thomas W.; Mikulas, Martin M.

2001-01-01

Material wrinkles drastically alter the structural constitutive properties of thin films. Normally linear elastic materials, when wrinkled, become highly nonlinear and initially inelastic. Stiffness' reduced by 99% and negative Poisson's ratios are typically observed. This paper presents an effective continuum constitutive model for the elastic effects of material wrinkles in thin films. The model considers general two-dimensional stress and strain states (simultaneous bi-axial and shear stress/strain) and neglects out of plane bending. The constitutive model is derived from a traditional mechanics analysis of an idealized physical model of random material wrinkles. Model parameters are the directly measurable wrinkle characteristics of amplitude and wavelength. For these reasons, the equations are mechanistic and deterministic. The model is compared with bi-axial tensile test data for wrinkled Kaptong(Registered Trademark) HN and is shown to deterministically predict strain as a function of stress with an average RMS error of 22%. On average, fitting the model to test data yields an RMS error of 1.2%

Method of producing amorphous thin films

DOEpatents

Brusasco, Raymond M.

1992-01-01

Disclosed is a method of producing thin films by sintering which comprises: a. coating a substrate with a thin film of an inorganic glass forming parulate material possessing the capability of being sintered, and b. irridiating said thin film of said particulate material with a laser beam of sufficient power to cause sintering of said material below the temperature of liquidus thereof. Also disclosed is the article produced by the method claimed.

Method of producing amorphous thin films

DOEpatents

Brusasco, R.M.

1992-09-01

Disclosed is a method of producing thin films by sintering which comprises: (a) coating a substrate with a thin film of an inorganic glass forming material possessing the capability of being sintered; and (b) irradiating said thin film of said particulate material with a laser beam of sufficient power to cause sintering of said material below the temperature of liquidus thereof. Also disclosed is the article produced by the method claimed. 4 figs.

Neat monolayer tiling of molecularly thin two-dimensional materials in 1 min

PubMed Central

Matsuba, Kazuaki; Wang, Chengxiang; Saruwatari, Kazuko; Uesusuki, Yusuke; Akatsuka, Kosho; Osada, Minoru; Ebina, Yasuo; Ma, Renzhi; Sasaki, Takayoshi

2017-01-01

Controlled arrangement of molecularly thin two-dimensional (2D) materials on a substrate, particularly into precisely organized mono- and multilayer structures, is a key to design a nanodevice using their unique and enhanced physical properties. Several techniques such as mechanical transfer process and Langmuir-Blodgett deposition have been applied for this purpose, but they have severe restrictions for large-scale practical applications, for example, limited processable area and long fabrication time, requiring skilled multistep operations. We report a facile one-pot spin-coating method to realize dense monolayer tiling of various 2D materials, such as graphene and metal oxide nanosheets, within 1 min over a wide area (for example, a 30-mmφ substrate). Centrifugal force drives the nanosheets in a thin fluid layer to the substrate edge where they are packed edge to edge all the way to the central region, without forming overlaps. We investigated the relationship between precursor concentration, rotation speed, and ultraviolet-visible absorbance and developed an effective method to optimize the parameters for neat monolayer films. The multilayer buildup is feasible by repeating the spin-coating process combined with a heat treatment at moderate temperature. This versatile solution-based technique will provide both fundamental and practical advancements in the rapid large-scale production of artificial lattice-like films and nanodevices based on 2D materials. PMID:28695198

Method of forming particulate materials for thin-film solar cells

DOEpatents

Eberspacher, Chris; Pauls, Karen Lea

2004-11-23

A method for preparing particulate materials useful in fabricating thin-film solar cells is disclosed. Particulate materials is prepared by the method include for example materials comprising copper and indium and/or gallium in the form of single-phase, mixed-metal oxide particulates; multi-phase, mixed-metal particulates comprising a metal oxide; and multinary metal particulates.

Thin Crystal Film Polarizer for Display Application

NASA Astrophysics Data System (ADS)

Paukshto, Michael

2003-03-01

Optiva Inc. has pioneered the development of nano-thin crystalline film (TCF) optical coatings for use in information displays and other applications. TCF is a material based on water-based dichroic dye solutions. Disk-like dye molecules aggregate in a ``plane-to-plane" manner; this self-assembly results in formation of highly anisometric rod-like stacks. These stacks have an aspect ratio of approximately 200:1. At a certain threshold of dye concentration, a nematic ordering of the rod-like stacks appears. Such a system acquires polarizing properties according to the following mechanism. Flow-induced alignment is known to occur in the lyotropic systems in a shear flow. In our case, the material undergoes shear alignment while being coated onto a glass or plastic substrate. In the coated thin film, the long molecular stacks are oriented in the flow direction parallel to the flow direction and substrate plane. The planes of the dye molecules are perpendicular to the substrate plane with the optical transition oscillators lying in the molecule plane. After the coating, as the thin film dries, crystallization occurs due to water evaporation. In a dry film, the molecular planes maintain their orthogonal orientation with respect to the substrate surface. TCF is known to possess properties of an E-mode polarizer. TCF technology has now migrated out of the R stage into manufacturing and is currently being incorporated into new display products. This presentation will provide an overview of TCF technology. The first part of the presentation will describe material structure, optical properties and characterization, material processing and associated coating equipment. This will be followed by a presentation on optical modeling and simulation of display performance with TCF components. Comparisons of display performance will be made for exemplar configurations of a variety of LCDs, including TN, STN and AMLCD designs in both transmissive and reflective modes.

Multifunctional thin film surface

DOEpatents

Brozik, Susan M.; Harper, Jason C.; Polsky, Ronen; Wheeler, David R.; Arango, Dulce C.; Dirk, Shawn M.

2015-10-13

A thin film with multiple binding functionality can be prepared on an electrode surface via consecutive electroreduction of two or more aryl-onium salts with different functional groups. This versatile and simple method for forming multifunctional surfaces provides an effective means for immobilization of diverse molecules at close proximities. The multifunctional thin film has applications in bioelectronics, molecular electronics, clinical diagnostics, and chemical and biological sensing.

Understanding polymorphism in organic semiconductor thin films through nanoconfinement.

PubMed

Diao, Ying; Lenn, Kristina M; Lee, Wen-Ya; Blood-Forsythe, Martin A; Xu, Jie; Mao, Yisha; Kim, Yeongin; Reinspach, Julia A; Park, Steve; Aspuru-Guzik, Alán; Xue, Gi; Clancy, Paulette; Bao, Zhenan; Mannsfeld, Stefan C B

2014-12-10

Understanding crystal polymorphism is a long-standing challenge relevant to many fields, such as pharmaceuticals, organic semiconductors, pigments, food, and explosives. Controlling polymorphism of organic semiconductors (OSCs) in thin films is particularly important given that such films form the active layer in most organic electronics devices and that dramatic changes in the electronic properties can be induced even by small changes in the molecular packing. However, there are very few polymorphic OSCs for which the structure-property relationships have been elucidated so far. The major challenges lie in the transient nature of metastable forms and the preparation of phase-pure, highly crystalline thin films for resolving the crystal structures and evaluating the charge transport properties. Here we demonstrate that the nanoconfinement effect combined with the flow-enhanced crystal engineering technique is a powerful and likely material-agnostic method to identify existing polymorphs in OSC materials and to prepare the individual pure forms in thin films at ambient conditions. With this method we prepared high quality crystal polymorphs and resolved crystal structures of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene), including a new polymorph discovered via in situ grazing incidence X-ray diffraction and confirmed by molecular mechanic simulations. We further correlated molecular packing with charge transport properties using quantum chemical calculations and charge carrier mobility measurements. In addition, we applied our methodology to a [1]benzothieno[3,2-b][1]1benzothiophene (BTBT) derivative and successfully stabilized its metastable form.

Structural Evolution of Low-Molecular-Weight Poly(ethylene oxide)-block-polystyrene Diblock Copolymer Thin Film

PubMed Central

Huang, Xiaohua

2013-01-01

The structural evolution of low-molecular-weight poly(ethylene oxide)-block-polystyrene (PEO-b-PS) diblock copolymer thin film with various initial film thicknesses on silicon substrate under thermal annealing was investigated by atomic force microscopy, optical microscopy, and contact angle measurement. At film thickness below half of the interlamellar spacing of the diblock copolymer (6.2 nm), the entire silicon is covered by a polymer brush with PEO blocks anchored on the Si substrate due to the substrate-induced effect. When the film is thicker than 6.2 nm, a dense polymer brush which is equal to half of an interlamellar layer was formed on the silicon, while the excess material dewet this layer to form droplets. The droplet surface was rich with PS block and the PEO block crystallized inside the bigger droplet to form spherulite. PMID:24302862

Molecular dynamics simulations of disjoining pressure effects in ultra-thin water films on a metal surface

NASA Astrophysics Data System (ADS)

Hu, Han; Sun, Ying

2013-11-01

Disjoining pressure, the excess pressure in an ultra-thin liquid film as a result of van der Waals interactions, is important in lubrication, wetting, flow boiling, and thin film evaporation. The classic theory of disjoining pressure is developed for simple monoatomic liquids. However, real world applications often utilize water, a polar liquid, for which fundamental understanding of disjoining pressure is lacking. In the present study, molecular dynamics (MD) simulations are used to gain insights into the effect of disjoining pressure in a water thin film. Our MD models were firstly validated against Derjaguin's experiments on gold-gold interactions across a water film and then verified against disjoining pressure in an argon thin film using the Lennard-Jones potential. Next, a water thin film adsorbed on a gold surface was simulated to examine the change of vapor pressure with film thickness. The results agree well with the classic theory of disjoining pressure, which implies that the polar nature of water molecules does not play an important role. Finally, the effects of disjoining pressure on thin film evaporation in nanoporous membrane and on bubble nucleation are discussed.

Symposium Q: Magnetic Thin Films, Heterostructures, and Device Materials

DTIC Science & Technology

2007-05-22

results in the formation of sodium carboxylate groups, that electronics, also known as magnetoelectronics or spintronics. Mn promoted the adsorption of...Q8.29 Magnetic Properties of Microcrystalline Si Thin films and Nickel Silicide Nanowires. Joondong Kim’, Seongjin Jang 2 , Bi-Ching Shih 2 , Hao...Buffalo, New York. The silicides , such as NiSi 2 and CoSi2 , have been attractive materials to crystallize Si and grow an epitaxial Si film with a small

Molecular and electronic structure of thin films of protoporphyrin(IX)Fe(III)Cl

NASA Astrophysics Data System (ADS)

Snyder, Shelly R.; White, Henry S.

1991-11-01

Electrochemical, scanning tunneling microscopy (STM), and tunneling spectroscopy studies of the molecular and electronic properties of thin films of protoporphyrin(IX)Fe(III)Cl (abbreviated as PP(IX)Fe(III)Cl) on highly oriented pyrolytic graphite (HOPG) electrodes are reported. PP(IX)Fe(III)Cl films are prepared by two different methods: (1) adsorption, yielding an electrochemically-active film, and (2) irreversible electrooxidative polymerization, yielding an electrochemically-inactive film. STM images, in conjunction with electro-chemical results, indicate that adsorption of PP(IX)Fe(III)Cl from aqueous solutions onto freshly cleaved HOPG results in a film comprised of molecular aggregates. In contrast, films prepared by irreversible electrooxidative polymerization of PP(IX)Fe(III)Cl have a denser, highly structured morphology, including what appear to be small pinholes (approx. 50A diameter) in an otherwise continuous film.

Molecularly thin fluoro-polymeric nanolubricant films: tribology, rheology, morphology, and applications.

PubMed

Chung, Pil Seung; Jhon, Myung S; Choi, Hyoung Jin

2016-03-21

Molecularly thin perfluoropolyether (PFPE) has been used extensively as a high-performance lubricant in various applications and, more importantly, on carbon overcoats to enhance the reliability and lubrication of micro-/nanoelectro-mechanical systems, where the tribological performance caused by its molecular architecture is a critical issue, as are its physical properties and rheological characteristics. This Highlight addresses recent trends in the development of fluoro-polymeric lubricant films with regard to their tribology, rheology, and physio-chemical properties as they relate to heat-assisted magnetic recording. Nanorheology has been employed to examine the dynamic response of nonfunctional and functional PFPEs, while the viscoelastic properties of nanoscale PFPE films and the relaxation processes as a function of molecular structure and end-group functionality were analyzed experimentally; furthermore, the characteristics of binary blends were reported.

Structural control of In2Se3 polycrystalline thin films by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Okamoto, T.; Nakada, Y.; Aoki, T.; Takaba, Y.; Yamada, A.; Konagai, M.

2006-09-01

Structural control of In2Se3 polycrystalline thin films was attempted by molecular beam epitaxy (MBE) technique. In2Se3 polycrystalline films were obtained on glass substrates at substrate temperatures above 400 °C. VI/III ratio greatly affected crystal structure of In2Se3 polycrystalline films. Mixtures of -In2Se3 and γ-In2Se3 were obtained at VI/III ratios greater than 20, and layered InSe polycrystalline films were formed at VI/III ratios below 1. γ-In2Se3 polycrystalline thin films without α-phase were successfully deposited with VI/III ratios in a range of 2 to 4. Photocurrent spectra of the γ-In2Se3 polycrystalline films showed an abrupt increase at approximately 1.9 eV, which almost corresponds with the reported bandgap of γ-In2Se3. Dark conductivity and photoconductivity measured under solar simulator light (AM 1.5, 100 mW/cm2) were approximately 10-9 and 10-5 S/cm in the γ-In2Se3 polycrystalline thin films, respectively.

Molecular solution processing of metal chalcogenide thin film solar cells

NASA Astrophysics Data System (ADS)

Yang, Wenbing

The barrier to utilize solar generated electricity mainly comes from their higher cost relative to fossil fuels. However, innovations with new materials and processing techniques can potentially make cost effective photovoltaics. One such strategy is to develop solution processed photovoltaics which avoid the expensive vacuum processing required by traditional solar cells. The dissertation is mainly focused on two absorber material system for thin film solar cells: chalcopyrite CuIn(S,Se)2 (CISS) and kesterite Cu2ZnSn(S,Se) 4 organized in chronological order. Chalcopyrite CISS is a very promising material. It has been demonstrated to achieve the highest efficiency among thin film solar cells. Scaled-up industry production at present has reached the giga-watt per year level. The process however mainly relies on vacuum systems which account for a significant percentage of the manufacturing cost. In the first section of this dissertation, hydrazine based solution processed CISS has been explored. The focus of the research involves the procedures to fabricate devices from solution. The topics covered in Chapter 2 include: precursor solution synthesis with a focus on understanding the solution chemistry, CISS absorber formation from precursor, properties modification toward favorable device performance, and device structure innovation toward tandem device. For photovoltaics to have a significant impact toward meeting energy demands, the annual production capability needs to be on TW-level. On such a level, raw materials supply of rare elements (indium for CIS or tellurium for CdTe) will be the bottleneck limiting the scalability. Replacing indium with zinc and tin, earth abundant kesterite CZTS exhibits great potential to reach the goal of TW-level with no limitations on raw material availability. Chapter 3 shows pioneering work towards solution processing of CZTS film at low temperature. The solution processed devices show performances which rival vacuum

Multi-Material Front Contact for 19% Thin Film Solar Cells.

PubMed

van Deelen, Joop; Tezsevin, Yasemin; Barink, Marco

2016-02-06

The trade-off between transmittance and conductivity of the front contact material poses a bottleneck for thin film solar panels. Normally, the front contact material is a metal oxide and the optimal cell configuration and panel efficiency were determined for various band gap materials, representing Cu(In,Ga)Se₂ (CIGS), CdTe and high band gap perovskites. Supplementing the metal oxide with a metallic copper grid improves the performance of the front contact and aims to increase the efficiency. Various front contact designs with and without a metallic finger grid were calculated with a variation of the transparent conductive oxide (TCO) sheet resistance, scribing area, cell length, and finger dimensions. In addition, the contact resistance and illumination power were also assessed and the optimal thin film solar panel design was determined. Adding a metallic finger grid on a TCO gives a higher solar cell efficiency and this also enables longer cell lengths. However, contact resistance between the metal and the TCO material can reduce the efficiency benefit somewhat.

Growth, characterization and post-processing of inorganic and hybrid organic-inorganic thin films deposited using atomic and molecular layer deposition techniques

NASA Astrophysics Data System (ADS)

Abdulagatov, Aziz Ilmutdinovich

Atomic layer deposition (ALD) and molecular layer deposition (MLD) are advanced thin film coating techniques developed for deposition of inorganic and hybrid organic-inorganic films respectively. Decreasing device dimensions and increasing aspect ratios in semiconductor processing has motivated developments in ALD. The beginning of this thesis will cover study of new ALD chemistry for high dielectric constant Y 2O3. In addition, the feasibility of conducting low temperature ALD of TiN and TiAlN is explored using highly reactive hydrazine as a new nitrogen source. Developments of these ALD processes are important for the electronics industry. As the search for new materials with more advanced properties continues, attention has shifted toward exploring the synthesis of hierarchically nanostructured thin films. Such complex architectures can provide novel functions important to the development of state of the art devices for the electronics industry, catalysis, energy conversion and memory storage as a few examples. Therefore, the main focus of this thesis is on the growth, characterization, and post-processing of ALD and MLD films for fabrication of novel composite (nanostructured) thin films. Novel composite materials are created by annealing amorphous ALD oxide alloys in air and by heat treatment of hybrid organic-inorganic MLD films in inert atmosphere (pyrolysis). The synthesis of porous TiO2 or Al2O3 supported V2O5 for enhanced surface area catalysis was achieved by the annealing of inorganic TiVxOy and AlV xOy ALD films in air. The interplay between phase separation, surface energy difference, crystallization, and melting temperature of individual oxides were studied for their control of film morphology. In other work, a class of novel metal oxide-graphitic carbon composite thin films was produced by pyrolysis of MLD hybrid organic-inorganic films. For example, annealing in argon of titania based hybrid films enabled fabrication of thin films of intimately

Flat-lying semiconductor-insulator interfacial layer in DNTT thin films.

PubMed

Jung, Min-Cherl; Leyden, Matthew R; Nikiforov, Gueorgui O; Lee, Michael V; Lee, Han-Koo; Shin, Tae Joo; Takimiya, Kazuo; Qi, Yabing

2015-01-28

The molecular order of organic semiconductors at the gate dielectric is the most critical factor determining carrier mobility in thin film transistors since the conducting channel forms at the dielectric interface. Despite its fundamental importance, this semiconductor-insulator interface is not well understood, primarily because it is buried within the device. We fabricated dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) thin film transistors by thermal evaporation in vacuum onto substrates held at different temperatures and systematically correlated the extracted charge mobility to the crystal grain size and crystal orientation. As a result, we identify a molecular layer of flat-lying DNTT molecules at the semiconductor-insulator interface. It is likely that such a layer might form in other material systems as well, and could be one of the factors reducing charge transport. Controlling this interfacial flat-lying layer may raise the ultimate possible device performance for thin film devices.

Thin film growth studies using time-resolved x-ray scattering

NASA Astrophysics Data System (ADS)

Kowarik, Stefan

2017-02-01

Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.

Thin film growth studies using time-resolved x-ray scattering.

PubMed

Kowarik, Stefan

2017-02-01

Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.

Thin-film Rechargeable Lithium Batteries

DOE R&D Accomplishments Database

Dudney, N. J.; Bates, J. B.; Lubben, D.

1995-06-01

Thin film rechargeable lithium batteries using ceramic electrolyte and cathode materials have been fabricated by physical deposition techniques. The lithium phosphorous oxynitride electrolyte has exceptional electrochemical stability and a good lithium conductivity. The lithium insertion reaction of several different intercalation materials, amorphous V{sub 2}O{sub 5}, amorphous LiMn{sub 2}O{sub 4}, and crystalline LiMn{sub 2}O{sub 4} films, have been investigated using the completed cathode/electrolyte/lithium thin film battery.

Thin-Film Power Transformers

NASA Technical Reports Server (NTRS)

Katti, Romney R.

1995-01-01

Transformer core made of thin layers of insulating material interspersed with thin layers of ferromagnetic material. Flux-linking conductors made of thinner nonferromagnetic-conductor/insulator multilayers wrapped around core. Transformers have geometric features finer than those of transformers made in customary way by machining and mechanical pressing. In addition, some thin-film materials exhibit magnetic-flux-carrying capabilities superior to those of customary bulk transformer materials. Suitable for low-cost, high-yield mass production.

Exploiting Molecular Weight Distribution Shape to Tune Domain Spacing in Block Copolymer Thin Films.

PubMed

Gentekos, Dillon T; Jia, Junteng; Tirado, Erika S; Barteau, Katherine P; Smilgies, Detlef-M; DiStasio, Robert A; Fors, Brett P

2018-04-04

We report a method for tuning the domain spacing ( D sp ) of self-assembled block copolymer thin films of poly(styrene- block-methyl methacrylate) (PS- b-PMMA) over a large range of lamellar periods. By modifying the molecular weight distribution (MWD) shape (including both the breadth and skew) of the PS block via temporal control of polymer chain initiation in anionic polymerization, we observe increases of up to 41% in D sp for polymers with the same overall molecular weight ( M n ≈ 125 kg mol -1 ) without significantly changing the overall morphology or chemical composition of the final material. In conjunction with our experimental efforts, we have utilized concepts from population statistics and least-squares analysis to develop a model for predicting D sp based on the first three moments of the MWDs. This statistical model reproduces experimental D sp values with high fidelity (with mean absolute errors of 1.2 nm or 1.8%) and provides novel physical insight into the individual and collective roles played by the MWD moments in determining this property of interest. This work demonstrates that both MWD breadth and skew have a profound influence over D sp , thereby providing an experimental and conceptual platform for exploiting MWD shape as a simple and modular handle for fine-tuning D sp in block copolymer thin films.

An energy landscape based approach for studying supercooled liquid and glassy thin films

NASA Astrophysics Data System (ADS)

Shah, Pooja; Mittal, Jeetain; Truskett, Thomas M.

2004-03-01

Materials in confined spaces are important in science and technology. Examples include biological fluids in membranes, liquids trapped in porous rocks, and thin-film materials used in high-resolution patterning technologies. However, few reliable rules exist to predict how the properties of materials will be affected by thin-film confinement. We have recently shown that the potential energy landscape formalism can be used to study, by both theory [1] and simulation [2], how the behavior of thin-film materials depends on sample dimensions and film-substrate interactions. Our landscape-based mean-field theory [1] can be used to study both the thermodynamic properties and the ideal glass transition of thin films. It predicts that, in the case of neutral or repulsive walls, the ideal glass transition temperature is lowered by decreasing film thickness. This is in qualitative agreement with experimental trends for the kinetic glass transition in confined fluids. Landscape-based approaches are also valuable for understanding the structural and mechanical properties of thin-film glasses. We demonstrate how the concept of an "equation of state of the energy landscape" [3] can be generalized to thin films [1, 2], where it gives insights into potential molecular mechanisms of tensile strength. [1] T. M. Truskett and V. Ganesan, J. Chem. Phys. 119, 1897-1900(2003); J. Mittal, P. Shah and T. M. Truskett, to be submitted to Langmuir. [2] P. Shah and T. M. Truskett, to be submitted to J. Phys. Chem. B. [3] S. Sastry, P. G. Debenedetti and F. H. Stillinger, Phys. Rev. E 56, 5533 (1997)

Molecular Based Temperature and Strain Rate Dependent Yield Criterion for Anisotropic Elastomeric Thin Films

NASA Technical Reports Server (NTRS)

Bosi, F.; Pellegrino, S.

2017-01-01

A molecular formulation of the onset of plasticity is proposed to assess temperature and strain rate effects in anisotropic semi-crystalline rubbery films. The presented plane stress criterion is based on the strain rate-temperature superposition principle and the cooperative theory of yielding, where some parameters are assumed to be material constants, while others are considered to depend on specific modes of deformation. An orthotropic yield function is developed for a linear low density polyethylene thin film. Uniaxial and biaxial inflation experiments were carried out to determine the yield stress of the membrane via a strain recovery method. It is shown that the 3% offset method predicts the uniaxial elastoplastic transition with good accuracy. Both the tensile yield points along the two principal directions of the film and the biaxial yield stresses are found to obey the superposition principle. The proposed yield criterion is compared against experimental measurements, showing excellent agreement over a wide range of deformation rates and temperatures.

CeCo5 thin films with perpendicular anisotropy grown by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Sharma, S.; Hildebrandt, E.; Major, M.; Komissinskiy, P.; Radulov, I.; Alff, L.

2018-04-01

Buffer-free, highly textured (0 0 1) oriented CeCo5 thin films showing perpendicular magnetic anisotropy were synthesized on (0 0 1) Al2O3 substrates by molecular beam epitaxy. Ce exists in a mixture of Ce3+ and Ce4+ valence states as shown by X-ray photoelectron spectroscopy. The first anisotropy constant, K1, as measured by torque magnetometry was 0.82 MJ/m3 (8.2 ×106erg /cm3) . A maximum coercivity of 5.16 kOe with a negative temperature coefficient of -0.304%K-1 and a magnetization of 527.30 emu/cm3 was measured perpendicular to the film plane at 5 K. In addition, a large anisotropy of the magnetic moment of 15.5% was observed. These magnetic parameters make CeCo5 a potential candidate material for spintronic and magnetic recording applications.

Harnessing Thin-Film Continuous-Flow Assembly Lines.

PubMed

Britton, Joshua; Castle, Jared W; Weiss, Gregory A; Raston, Colin L

2016-07-25

Inspired by nature's ability to construct complex molecules through sequential synthetic transformations, an assembly line synthesis of α-aminophosphonates has been developed. In this approach, simple starting materials are continuously fed through a thin-film reactor where the intermediates accrue molecular complexity as they progress through the flow system. Flow chemistry allows rapid multistep transformations to occur via reaction compartmentalization, an approach not amenable to using conventional flasks. Thin film processing can also access facile in situ solvent exchange to drive reaction efficiency, and through this method, α-aminophosphonate synthesis requires only 443 s residence time to produce 3.22 g h(-1) . Assembly-line synthesis allows unprecedented reaction flexibility and processing efficiency. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Far-infrared transmission in GaN, AlN, and AlGaN thin films grown by molecular beam epitaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ibanez, J.; Hernandez, S.; Alarcon-Llado, E.

2008-08-01

We present a far-infrared transmission study on group-III nitride thin films. Cubic GaN and AlN layers and c-oriented wurtzite GaN, AlN, and Al{sub x}Ga{sub 1-x}N (x<0.3) layers were grown by molecular beam epitaxy on GaAs and Si(111) substrates, respectively. The Berreman effect allows us to observe simultaneously the transverse optic and the longitudinal optic phonons of both the cubic and the hexagonal films as transmission minima in the infrared spectra acquired with obliquely incident radiation. We discuss our results in terms of the relevant electromagnetic theory of infrared transmission in cubic and wurtzite thin films. We compare the infrared resultsmore » with visible Raman-scattering measurements. In the case of films with low scattering volumes and/or low Raman efficiencies and also when the Raman signal of the substrate material obscures the weaker peaks from the nitride films, we find that the Berreman technique is particularly useful to complement Raman spectroscopy.« less

Poly(vinyl acetate)/clay nanocomposite materials for organic thin film transistor application.

PubMed

Park, B J; Sung, J H; Park, J H; Choi, J S; Choi, H J

2008-05-01

Nanocomposite materials of poly(vinyl acetate) (PVAc) and organoclay were fabricated, in order to be utilized as dielectric materials of the organic thin film transistor (OTFT). Spin coating condition of the nanocomposite solution was examined considering shear viscosity of the composite materials dissolved in chloroform. Intercalated structure of the PVAc/clay nanocomposites was characterized using both wide-angle X-ray diffraction and TEM. Fracture morphology of the composite film on silicon wafer was also observed by SEM. Dielectric constant (4.15) of the nanocomposite materials shows that the PVAc/clay nanocomposites are applicable for the gate dielectric materials.

An overview of thin film nitinol endovascular devices.

PubMed

Shayan, Mahdis; Chun, Youngjae

2015-07-01

Thin film nitinol has unique mechanical properties (e.g., superelasticity), excellent biocompatibility, and ultra-smooth surface, as well as shape memory behavior. All these features along with its low-profile physical dimension (i.e., a few micrometers thick) make this material an ideal candidate in developing low-profile medical devices (e.g., endovascular devices). Thin film nitinol-based devices can be collapsed and inserted in remarkably smaller diameter catheters for a wide range of catheter-based procedures; therefore, it can be easily delivered through highly tortuous or narrow vascular system. A high-quality thin film nitinol can be fabricated by vacuum sputter deposition technique. Micromachining techniques were used to create micro patterns on the thin film nitinol to provide fenestrations for nutrition and oxygen transport and to increase the device's flexibility for the devices used as thin film nitinol covered stent. In addition, a new surface treatment method has been developed for improving the hemocompatibility of thin film nitinol when it is used as a graft material in endovascular devices. Both in vitro and in vivo test data demonstrated a superior hemocompatibility of the thin film nitinol when compared with commercially available endovascular graft materials such as ePTFE or Dacron polyester. Promising features like these have motivated the development of thin film nitinol as a novel biomaterial for creating endovascular devices such as stent grafts, neurovascular flow diverters, and heart valves. This review focuses on thin film nitinol fabrication processes, mechanical and biological properties of the material, as well as current and potential thin film nitinol medical applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

An Observation of Diamond-Shaped Particle Structure in a Soya Phosphatidylcohline and Bacteriorhodopsin Composite Langmuir Blodgett Film Fabricated by Multilayer Molecular Thin Film Method

NASA Astrophysics Data System (ADS)

Tsujiuchi, Y.; Makino, Y.

A composite film of soya phosphatidylcohline (soya PC) and bacteriorhodopsin (BR) was fabricated by the multilayer molecular thin film method using fatty acid and lipid on a quartz substrate. Direct Force Microscopy (DFM), UV absorption spectra and IR absorption spectra of the film were characterized on the detail of surface structure of the film. The DFM data revealed that many rhombus (diamond-shaped) particles were observed in the film. The spectroscopic data exhibited the yield of M-intermediate of BR in the film. On our modelling of molecular configuration indicate that the coexistence of the strong inter-molecular interaction and the strong inter-molecular interaction between BR trimmers attributed to form the particles.

Self-Limited Growth in Pentacene Thin Films

PubMed Central

2017-01-01

Pentacene is one of the most studied organic semiconducting materials. While many aspects of the film formation have already been identified in very thin films, this study provides new insight into the transition from the metastable thin-film phase to bulk phase polymorphs. This study focuses on the growth behavior of pentacene within thin films as a function of film thickness ranging from 20 to 300 nm. By employing various X-ray diffraction methods, combined with supporting atomic force microscopy investigations, one crystalline orientation for the thin-film phase is observed, while three differently tilted bulk phase orientations are found. First, bulk phase crystallites grow with their 00L planes parallel to the substrate surface; second, however, crystallites tilted by 0.75° with respect to the substrate are found, which clearly dominate the former in ratio; third, a different bulk phase polymorph with crystallites tilted by 21° is found. The transition from the thin-film phase to the bulk phase is rationalized by the nucleation of the latter at crystal facets of the thin-film-phase crystallites. This leads to a self-limiting growth of the thin-film phase and explains the thickness-dependent phase behavior observed in pentacene thin films, showing that a large amount of material is present in the bulk phase much earlier during the film growth than previously thought. PMID:28287698

Self-Limited Growth in Pentacene Thin Films.

PubMed

Pachmajer, Stefan; Jones, Andrew O F; Truger, Magdalena; Röthel, Christian; Salzmann, Ingo; Werzer, Oliver; Resel, Roland

2017-04-05

Pentacene is one of the most studied organic semiconducting materials. While many aspects of the film formation have already been identified in very thin films, this study provides new insight into the transition from the metastable thin-film phase to bulk phase polymorphs. This study focuses on the growth behavior of pentacene within thin films as a function of film thickness ranging from 20 to 300 nm. By employing various X-ray diffraction methods, combined with supporting atomic force microscopy investigations, one crystalline orientation for the thin-film phase is observed, while three differently tilted bulk phase orientations are found. First, bulk phase crystallites grow with their 00L planes parallel to the substrate surface; second, however, crystallites tilted by 0.75° with respect to the substrate are found, which clearly dominate the former in ratio; third, a different bulk phase polymorph with crystallites tilted by 21° is found. The transition from the thin-film phase to the bulk phase is rationalized by the nucleation of the latter at crystal facets of the thin-film-phase crystallites. This leads to a self-limiting growth of the thin-film phase and explains the thickness-dependent phase behavior observed in pentacene thin films, showing that a large amount of material is present in the bulk phase much earlier during the film growth than previously thought.

Molecular separations using nanostructured porous thin films fabricated by glancing angle deposition

NASA Astrophysics Data System (ADS)

Bezuidenhout, Louis Wentzel

Biomolecular separation techniques are an enabling technology that indirectly in.uence many aspects of our lives. Advances have led to faster analyses, reduced costs, higher specificity, and new analytical techniques, impacting areas such as health care, environmental monitoring, polymer sciences, agriculture, and nutrition. Further development of separations technology is anticipated to follow the path of computing technology such that miniaturization through the development of microfluidics technology, lab-on-a-chip systems, and other integrative, multi-component systems will further extend our analysis capabilities. Creation of new and improvement of existing separation technologies is an integral part of the pathway to miniaturized systems. the work of this thesis investigates molecular separations using porous nanostructured films fabricated by the thin film process glancing angle deposition (GLAD). Structural architecture, pore size and shape, and film density can be finely controlled to produce high-surface area thin films with engineered morphology. The characteristic size scales and structural control of GLAD films are well-suited to biomolecules and separation techniques, motivating investigation into the utility and performance of GLAD films for biomolecular separations. This project consisted of three phases. First, chromatographic separation of dye molecules on silica GLAD films was demonstrated by thin layer chromatography Direct control of film nanostructure altered the separation characteristics; most strikingly, anisotropic structures provided two-dimensional analyte migration. Second, nanostructures made with GLAD were integrated in PDMS microfluidic channels using a sacrificial etching process; DNA molecules (10/48 kbp and 6/10/20 kbp mixtures) were electrophoretically separated on a microfluidic chip using a porous bed of SiO2 vertical posts. Third, mass spectrometry of proteins and drugs in the mass range of 100-1300 m/z was performed using

Film and membrane-model thermodynamics of free thin liquid films.

PubMed

Radke, C J

2015-07-01

In spite of over 7 decades of effort, the thermodynamics of thin free liquid films (as in emulsions and foams) lacks clarity. Following a brief review of the meaning and measurement of thin-film forces (i.e., conjoining/disjoining pressures), we offer a consistent analysis of thin-film thermodynamics. By carefully defining film reversible work, two distinct thermodynamic formalisms emerge: a film model with two zero-volume membranes each of film tension γ(f) and a membrane model with a single zero-volume membrane of membrane tension 2γ(m). In both models, detailed thermodynamic analysis gives rise to thin-film Gibbs adsorption equations that allow calculation of film and membrane tensions from measurements of disjoining-pressure isotherms. A modified Young-Laplace equation arises in the film model to calculate film-thickness profiles from the film center to the surrounding bulk meniscus. No corresponding relation exists in the membrane model. Illustrative calculations of disjoining-pressure isotherms for water are presented using square-gradient theory. We report considerable deviations from Hamaker theory for films less than about 3 nm in thickness. Such thin films are considerably more attractive than in classical Hamaker theory. Available molecular simulations reinforce this finding. Copyright © 2014 Elsevier Inc. All rights reserved.

A thin film nitinol heart valve.

PubMed

Stepan, Lenka L; Levi, Daniel S; Carman, Gregory P

2005-11-01

In order to create a less thrombogenic heart valve with improved longevity, a prosthetic heart valve was developed using thin film nitinol (NiTi). A "butterfly" valve was constructed using a single, elliptical piece of thin film NiTi and a scaffold made from Teflon tubing and NiTi wire. Flow tests and pressure readings across the valve were performed in vitro in a pulsatile flow loop. Bio-corrosion experiments were conducted on untreated and passivated thin film nitinol. To determine the material's in vivo biocompatibility, thin film nitinol was implanted in pigs using stents covered with thin film NiTi. Flow rates and pressure tracings across the valve were comparable to those through a commercially available 19 mm Perimount Edwards tissue valve. No signs of corrosion were present on thin film nitinol samples after immersion in Hank's solution for one month. Finally, organ and tissue samples explanted from four pigs at 2, 3, 4, and 6 weeks after thin film NiTi implantation appeared without disease, and the thin film nitinol itself was without thrombus formation. Although long term testing is still necessary, thin film NiTi may be very well suited for use in artificial heart valves.

Thin film tritium dosimetry

DOEpatents

Moran, Paul R.

1976-01-01

The present invention provides a method for tritium dosimetry. A dosimeter comprising a thin film of a material having relatively sensitive RITAC-RITAP dosimetry properties is exposed to radiation from tritium, and after the dosimeter has been removed from the source of the radiation, the low energy electron dose deposited in the thin film is determined by radiation-induced, thermally-activated polarization dosimetry techniques.

Thermoelectric properties of epitaxial β-FeSi2 thin films grown on Si(111) substrates with various film qualities

NASA Astrophysics Data System (ADS)

Watanabe, Kentaro; Taniguchi, Tatsuhiko; Sakane, Shunya; Aoki, Shunsuke; Suzuki, Takeyuki; Fujita, Takeshi; Nakamura, Yoshiaki

2017-05-01

Si-based epitaxial β-FeSi2 thin films are attractive as materials for on-chip thermoelectric power generators. We investigated the structure, crystallinity, and thermoelectric properties of β-FeSi2 thin films epitaxially grown on Si(111) substrates by using three different techniques: conventional reactive deposition epitaxy followed by molecular beam epitaxy (RDE+MBE), solid phase epitaxy (SPE) based on codeposition of Fe and Si presented previously, and SPE followed by MBE (SPE+MBE) presented newly by this work. Their epitaxial growth temperatures were fixed at 530 °C for comparison. RDE+MBE thin films exhibited high crystalline quality, but rough surfaces and rugged β-FeSi2/Si(111) interfaces. On the other hand, SPE thin films showed flat surfaces and abrupt β-FeSi2/Si(111) interfaces but low crystallinity. We found that SPE+MBE thin films realized crystallinity higher than SPE thin films, and also had flatter surfaces and sharper interfaces than RDE+MBE thin films. In SPE+MBE thin film growth, due to the initial SPE process with low temperature codeposition, thermal interdiffusion of Fe and Si was suppressed, resulting in the surface flatness and abrupt interface. Second high temperature MBE process improved the crystallinity. We also investigated thermoelectric properties of these β-FeSi2 thin films. Structural factors affecting the thermoelectric properties of RDE+MBE, SPE, and SPE+MBE thin films were investigated.

Molecular Engineering for Enhanced Charge Transfer in Thin-Film Photoanode.

PubMed

Kim, Jeong Soo; Kim, Byung-Man; Kim, Un-Young; Shin, HyeonOh; Nam, Jung Seung; Roh, Deok-Ho; Park, Jun-Hyeok; Kwon, Tae-Hyuk

2017-10-11

We developed three types of dithieno[3,2-b;2',3'-d]thiophene (DTT)-based organic sensitizers for high-performance thin photoactive TiO 2 films and investigated the simple but powerful molecular engineering of different types of bonding between the triarylamine electron donor and the conjugated DTT π-bridge by the introduction of single, double, and triple bonds. As a result, with only 1.3 μm transparent and 2.5-μm TiO 2 scattering layers, the triple-bond sensitizer (T-DAHTDTT) shows the highest power conversion efficiency (η = 8.4%; V OC = 0.73 V, J SC = 15.4 mA·cm -2 , and FF = 0.75) in an iodine electrolyte system under one solar illumination (AM 1.5, 1000 W·m -2 ), followed by the single-bond sensitizer (S-DAHTDTT) (η = 7.6%) and the double-bond sensitizer (D-DAHTDTT) (η = 6.4%). We suggest that the superior performance of T-DAHTDTT comes from enhanced intramolecular charge transfer (ICT) induced by the triple bond. Consequently, T-DAHTDTT exhibits the most active photoelectron injection and charge transport on a TiO 2 film during operation, which leads to the highest photocurrent density among the systems studied. We analyzed these correlations mainly in terms of charge injection efficiency, level of photocharge storage, and charge-transport kinetics. This study suggests that the molecular engineering of a triple bond between the electron donor and the π-bridge of a sensitizer increases the performance of dye-sensitized solar cell (DSC) with a thin photoactive film by enhancing not only J SC through improved ICT but also V OC through the evenly distributed sensitizer surface coverage.

Applications of Thin Film Thermocouples for Surface Temperature Measurement

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Holanda, Raymond

1994-01-01

Thin film thermocouples provide a minimally intrusive means of measuring surface temperature in hostile, high temperature environments. Unlike wire thermocouples, thin films do not necessitate any machining of the surface, therefore leaving intact its structural integrity. Thin films are many orders of magnitude thinner than wire, resulting in less disruption to the gas flow and thermal patterns that exist in the operating environment. Thin film thermocouples have been developed for surface temperature measurement on a variety of engine materials. The sensors are fabricated in the NASA Lewis Research Center's Thin Film Sensor Lab, which is a class 1000 clean room. The thermocouples are platinum-13 percent rhodium versus platinum and are fabricated by the sputtering process. Thin film-to-leadwire connections are made using the parallel-gap welding process. Thermocouples have been developed for use on superalloys, ceramics and ceramic composites, and intermetallics. Some applications of thin film thermocouples are: temperature measurement of space shuttle main engine turbine blade materials, temperature measurement in gas turbine engine testing of advanced materials, and temperature and heat flux measurements in a diesel engine. Fabrication of thin film thermocouples is described. Sensor durability, drift rate, and maximum temperature capabilities are addressed.

Analysis of Hard Thin Film Coating

NASA Technical Reports Server (NTRS)

Shen, Dashen

1998-01-01

Marshall Space Flight Center (MSFC) is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using Electron Cyclotron Resonance Chemical Vapor Deposition (ECRCVD) to deposit hard thin film on stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Analysis of Hard Thin Film Coating

NASA Technical Reports Server (NTRS)

Shen, Dashen

1998-01-01

MSFC is interested in developing hard thin film coating for bearings. The wearing of the bearing is an important problem for space flight engine. Hard thin film coating can drastically improve the surface of the bearing and improve the wear-endurance of the bearing. However, many fundamental problems in surface physics, plasma deposition, etc, need further research. The approach is using electron cyclotron resonance chemical vapor deposition (ECRCVD) to deposit hard thin film an stainless steel bearing. The thin films in consideration include SiC, SiN and other materials. An ECRCVD deposition system is being assembled at MSFC.

Apparatus and method for treating a cathode material provided on a thin-film substrate

DOEpatents

Hanson, Eric J.; Kooyer, Richard L.

2001-01-01

An apparatus and method for treating a cathode material provided on a surface of a continuous thin-film substrate and a treated thin-film cathode having increased smoothness are disclosed. A web of untreated cathode material is moved between a feed mechanism and a take-up mechanism, and passed through a treatment station. The web of cathode material typically includes areas having surface defects, such as prominences extending from the surface of the cathode material. The surface of the cathode material is treated with an abrasive material to reduce the height of the prominences so as to increase an 85 degree gloss value of the cathode material surface by at least approximately 10. The web of cathode material may be subjected to a subsequent abrasive treatment at the same or other treatment station. Burnishing or lapping film is employed at a treatment station to process the cathode material. An abrasive roller may alternatively be used to process the web of cathode material. The apparatus and method of the present invention may also be employed to treat the surface of a lithium anode foil so as to cleanse and reduce the roughness of the anode foil surface.

Apparatus and method for treating a cathode material provided on a thin-film substrate

DOEpatents

Hanson, Eric J.; Kooyer, Richard L.

2003-01-01

An apparatus and method for treating a cathode material provided on a surface of a continuous thin-film substrate and a treated thin-film cathode having increased smoothness are disclosed. A web of untreated cathode material is moved between a feed mechanism and a take-up mechanism, and passed through a treatment station. The web of cathode material typically includes areas having surface defects, such as prominences extending from the surface of the cathode material. The surface of the cathode material is treated with an abrasive material to reduce the height of the prominences so as to increase an 85 degree gloss value of the cathode material surface by at least approximately 10. The web of cathode material may be subjected to a subsequent abrasive treatment at the same or other treatment station. Burnishing or lapping film is employed at a treatment station to process the cathode material. An abrasive roller may alternatively be used to process the web of cathode material. The apparatus and method of the present invention may also be employed to treat the surface of a lithium anode foil so as to cleanse and reduce the roughness of the anode foil surface.

Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.

PubMed

Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

2009-11-09

Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing.

Control method and system for use when growing thin-films on semiconductor-based materials

DOEpatents

McKee, Rodney A.; Walker, Frederick J.

2001-01-01

A process and system for use during the growth of a thin film upon the surface of a substrate by exposing the substrate surface to vaporized material in a high vacuum (HV) facility involves the directing of an electron beam generally toward the surface of the substrate as the substrate is exposed to vaporized material so that electrons are diffracted from the substrate surface by the beam and the monitoring of the pattern of electrons diffracted from the substrate surface as vaporized material settles upon the substrate surface. When the monitored pattern achieves a condition indicative of the desired condition of the thin film being grown upon the substrate, the exposure of the substrate to the vaporized materials is shut off or otherwise adjusted. To facilitate the adjustment of the crystallographic orientation of the film relative to the electron beam, the system includes a mechanism for altering the orientation of the surface of the substrate relative to the electron beam.

Method for making surfactant-templated thin films

DOEpatents

Brinker, C. Jeffrey; Lu, Yunfeng; Fan, Hong You

2010-08-31

An evaporation-induced self-assembly method to prepare a porous, surfactant-templated, thin film by mixing a silica sol, a solvent, a surfactant, and an interstitial compound, evaporating a portion of the solvent to form a liquid, crystalline thin film mesophase material, and then removal of the surfactant template. Coating onto a substrate produces a thin film with the interstitial compound either covalently bonded to the internal surfaces of the ordered or disordered mesostructure framework or physically entrapped within the ordered or disordered mesostructured framework. Particles can be formed by aerosol processing or spray drying rather than coating onto a substrate. The selection of the interstitial compound provides a means for developing thin films for applications including membranes, sensors, low dielectric constant films, photonic materials and optical hosts.

Method for making surfactant-templated thin films

DOEpatents

Brinker, C. Jeffrey; Lu, Yunfeng; Fan, Hongyou

2002-01-01

An evaporation-induced self-assembly method to prepare a porous, surfactant-templated, thin film by mixing a silica sol, a solvent, a surfactant, and an interstitial compound, evaporating a portion of the solvent to form a liquid, crystalline thin film mesophase material, and then removal of the surfactant template. Coating onto a substrate produces a thin film with the interstitial compound either covalently bonded to the internal surfaces of the ordered or disordered mesostructure framework or physically entrapped within the ordered or disordered mesostructured framework. Particles can be formed by aerosol processing or spray drying rather than coating onto a substrate. The selection of the interstitial compound provides a means for developing thin films for applications including membranes, sensors, low dielectric constant films, photonic materials and optical hosts.

Primary research efforts on exploring the commercial possibilities of thin film growth and materials purification in space

NASA Technical Reports Server (NTRS)

1989-01-01

The progress made on research programs in the 1987 to 1988 year is reported. The research is aimed at producing thin film semiconductors and superconductor materials in space. Sophisticated vacuum chambers and equipment were attained for the epitaxial thin film growth of semiconductors, metals and superconductors. In order to grow the best possible epitaxial films at the lowest possible temperatures on earth, materials are being isoelectronically doped during growth. It was found that isoelectrically doped film shows the highest mobility in comparison with films grown at optimal temperatures. Success was also attained in growing epitaxial films of InSb on sapphire which show promise for infrared sensitive devices in the III-V semiconductor system.

Inelastic deformation of plasma polymerised thin films facilitated by transient dense plasma focus irradiation

NASA Astrophysics Data System (ADS)

Grant, Daniel S.; Rawat, Rajdeep S.; Bazaka, Kateryna; Jacob, Mohan V.

2017-09-01

The high degree of crosslinking present in plasma polymerised thin films, coupled with their high molecular weight, imbues these films with properties similar to those of thermosetting polymers. For instance, such films tend to be relatively hard, insoluble, and to date have not exhibited plasticity when subjected to elevated temperatures. In this paper it is demonstrated that plasma polymers can, in fact, undergo plastic deformation in response to the application of extremely short-lived thermal treatment delivered by a dense plasma focus device, as evidenced by the evolution of bubble-like structures from the thin film. This finding suggests new avenues for texturing plasma thin films, and synthesising cavities that may find utility as thermal insulators or domains for material encapsulation.

Pulsed—Laser Deposition Of Oxide Thin Films And Laser—Induced Breakdown Spectroscopy Of Multi—Element Materials

NASA Astrophysics Data System (ADS)

Pedarnig, Johannes D.

2010-10-01

New results of the Linz group on pulsed—laser deposition (PLD) of oxide thin films and on laser—induced breakdown spectroscopy (LIBS) of multi-element materials are reported. High-Tc superconducting (HTS) films with enhanced critical current density Jc are produced by laser ablation of novel nano-composite ceramic targets. The targets contain insulating nano-particles that are embedded into the YBa2Cu3O7 matrix. Epitaxial double-layers of lithium-doped and aluminum-doped ZnO are deposited on r-cut sapphire substrates. Acoustic over-modes in the GHz range are excited by piezoelectric actuation of layers. Smooth films of rare-earth doped glass are produced by F2—laser ablation. The transport properties of HTS thin films are modified by light—ion irradiation. Thin film nano—patterning is achieved by masked ion beam irradiation. LIBS is employed to analyze trace elements in industrial iron oxide powder and reference polymer materials. Various trace elements of ppm concentration are measured in the UV/VIS and vacuum-UV spectral range. Quantitative LIBS analysis of major components in oxide materials is performed by calibration-free methods.

Thin film growth of CaFe2As2 by molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Hatano, T.; Kawaguchi, T.; Fujimoto, R.; Nakamura, I.; Mori, Y.; Harada, S.; Ujihara, T.; Ikuta, H.

2016-01-01

Film growth of CaFe2As2 was realized by molecular beam epitaxy on six different substrates that have a wide variation in the lattice mismatch to the target compound. By carefully adjusting the Ca-to-Fe flux ratio, we obtained single-phase thin films for most of the substrates. Interestingly, an expansion of the CaFe2As2 lattice to the out-of-plane direction was observed for all films, even when an opposite strain was expected. A detailed microstructure observation of the thin film grown on MgO by transmission electron microscope revealed that it consists of cube-on-cube and 45°-rotated domains. The latter domains were compressively strained in plane, which caused a stretching along the c-axis direction. Because the domains were well connected across the boundary with no appreciable discontinuity, we think that the out-of-plane expansion in the 45°-rotated domains exerted a tensile stress on the other domains, resulting in the unexpectedly large c-axis lattice parameter, despite the apparently opposite lattice mismatch.

Pulsed laser deposition and characterization of cellulase thin films

NASA Astrophysics Data System (ADS)

Cicco, N.; Morone, A.; Verrastro, M.; Viggiano, V.

2013-08-01

Thin films of cellulase were obtained by pulsed laser deposition (PLD) on an appropriate substrate. Glycoside hydrolase cellulase has received our attention because it emerges among the antifouling enzymes (enzymes being able to remove and prevent the formation of micro-organism biofilms) used in industry and medicine field. Pressed cellulase pellets, used as target material, were ablated with pulses of a Nd-YAG laser working at wavelength of 532 nm. In this work, we evaluated the impact of PLD technique both on molecular structure and hydrolytic activity of cellulase. Characteristic chemical bonds and morphology of deposited layers were investigated by FTIR spectroscopy and SEM respectively. The hydrolytic activity of cellulase thin films was detected by a colorimetric assay.

Carbon Nanotube Thin-Film Antennas.

PubMed

Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

2016-08-17

Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of <10 ohm/sq is needed to achieve a 10 dB return loss in the unbalanced antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed.

Tuning polymorphism and orientation in organic semiconductor thin films via post-deposition processing.

PubMed

Hiszpanski, Anna M; Baur, Robin M; Kim, Bumjung; Tremblay, Noah J; Nuckolls, Colin; Woll, Arthur R; Loo, Yueh-Lin

2014-11-05

Though both the crystal structure and molecular orientation of organic semiconductors are known to impact charge transport in thin-film devices, separately accessing different polymorphs and varying the out-of-plane molecular orientation is challenging, typically requiring stringent control over film deposition conditions, film thickness, and substrate chemistry. Here we demonstrate independent tuning of the crystalline polymorph and molecular orientation in thin films of contorted hexabenzocoronene, c-HBC, during post-deposition processing without the need to adjust deposition conditions. Three polymorphs are observed, two of which have not been previously reported. Using our ability to independently tune the crystal structure and out-of-plane molecular orientation in thin films of c-HBC, we have decoupled and evaluated the effects that molecular packing and orientation have on device performance in thin-film transistors (TFTs). In the case of TFTs comprising c-HBC, polymorphism and molecular orientation are equally important; independently changing either one affects the field-effect mobility by an order of magnitude.

Oxide-based thin film transistors for flexible electronics

NASA Astrophysics Data System (ADS)

He, Yongli; Wang, Xiangyu; Gao, Ya; Hou, Yahui; Wan, Qing

2018-01-01

The continuous progress in thin film materials and devices has greatly promoted the development in the field of flexible electronics. As one of the most common thin film devices, thin film transistors (TFTs) are significant building blocks for flexible platforms. Flexible oxide-based TFTs are well compatible with flexible electronic systems due to low process temperature, high carrier mobility, and good uniformity. The present article is a review of the recent progress and major trends in the field of flexible oxide-based thin film transistors. First, an introduction of flexible electronics and flexible oxide-based thin film transistors is given. Next, we introduce oxide semiconductor materials and various flexible oxide-based TFTs classified by substrate materials including polymer plastics, paper sheets, metal foils, and flexible thin glass. Afterwards, applications of flexible oxide-based TFTs including bendable sensors, memories, circuits, and displays are presented. Finally, we give conclusions and a prospect for possible development trends. Project supported in part by the National Science Foundation for Distinguished Young Scholars of China (No. 61425020), in part by the National Natural Science Foundation of China (No. 11674162).

Flush Mounting Of Thin-Film Sensors

NASA Technical Reports Server (NTRS)

Moore, Thomas C., Sr.

1992-01-01

Technique developed for mounting thin-film sensors flush with surfaces like aerodynamic surfaces of aircraft, which often have compound curvatures. Sensor mounted in recess by use of vacuum pad and materials selected for specific application. Technique involves use of materials tailored to thermal properties of substrate in which sensor mounted. Together with customized materials, enables flush mounting of thin-film sensors in most situations in which recesses for sensors provided. Useful in both aircraft and automotive industries.

Young's modulus measurement of aluminum thin film with cantilever structure

NASA Astrophysics Data System (ADS)

Lee, ByoungChan; Lee, SangHun; Lee, Hwasu; Shin, Hyungjae

2001-09-01

Micromachined cantilever structures are commonly used for measuring mechanical properties of thin film materials in MEMS. The application of conventional cantilever theory in experiment raises severe problem. The deformation of the supporting post and flange is produced by the applied electrostatic force and lead to more reduced measurement value than real Young's modulus of thin film materials. In order to determine Young's modulus of aluminum thin film robustly and reproducibly, the modified cantilever structure is proposed. Two measurement methods, which are cantilever tip deflection measurement and resonant frequency measurement, are used for confirming the reliability of the proposed cantilever structure as well. Measured results indicate that the proposed measurement scheme provides useful and credible Young's modulus value for thin film materials with sub-micron thickness. The proved validation of the proposed scheme makes sure that in addition to Young's modulus of aluminum thin film, that of other thin film materials which are aluminum alloy, metal, and so forth, can be extracted easily and clearly.

Stretchable, adhesive and ultra-conformable elastomer thin films.

PubMed

Sato, Nobutaka; Murata, Atsushi; Fujie, Toshinori; Takeoka, Shinji

2016-11-16

Thermoplastic elastomers are attractive materials because of the drastic changes in their physical properties above and below the glass transition temperature (T g ). In this paper, we report that free-standing polystyrene (PS, T g : 100 °C) and polystyrene-polybutadiene-polystyrene triblock copolymer (SBS, T g : -70 °C) thin films with a thickness of hundreds of nanometers were prepared by a gravure coating method. Among the mechanical properties of these thin films determined by bulge testing and tensile testing, the SBS thin films exhibited a much lower elastic modulus (ca. 0.045 GPa, 212 nm thickness) in comparison with the PS thin films (ca. 1.19 GPa, 217 nm thickness). The lower elastic modulus and lower thickness of the SBS thin films resulted in higher conformability and thus higher strength of adhesion to an uneven surface such as an artificial skin model with roughness (R a = 10.6 μm), even though they both have similar surface energies. By analyzing the mechanical properties of the SBS thin films, the elastic modulus and thickness of the thin films were strongly correlated with their conformability to a rough surface, which thus led to a high adhesive strength. Therefore, the SBS thin films will be useful as coating layers for a variety of materials.

Molecular beam epitaxy growth of SmB6+/-δ thin films

NASA Astrophysics Data System (ADS)

Hoffman, Jason; Saleem, Muhammad; Day, James; Bonn, Doug; Hoffman, Jennifer

SmB6 has emerged as a leading candidate in the search for exotic topological states generated by strong interactions. The synthesis of epitaxial SmB6 thin films presents new avenues to control surface termination, thickness, and strain in this system. In this work, we use molecular beam epitaxy (MBE) to deposit SmB6+/-δ films on insulating (001)-oriented MgO substrates. We use ex-situ x-ray diffraction and magnetotransport measurements to assess the properties of the samples and compare them to previously reported values for single crystals. We also discuss the prospects of using rare-earth substitution to control the correlation strength and alter the topology of the bulk and surface electronic states.

Atomic layer deposition synthesized TiO{sub x} thin films and their application as microbolometer active materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanrikulu, Mahmud Yusuf, E-mail: mytanrikulu@adanabtu.edu.tr; Rasouli, Hamid Reza; Ghaffari, Mohammad

2016-05-15

This paper demonstrates the possible usage of TiO{sub x} thin films synthesized by atomic layer deposition as a microbolometer active material. Thin film electrical resistance is investigated as a function of thermal annealing. It is found that the temperature coefficient of resistance values can be controlled by coating/annealing processes, and the value as high as −9%/K near room temperature is obtained. The noise properties of TiO{sub x} films are characterized. It is shown that TiO{sub x} films grown by atomic layer deposition technique could have a significant potential to be used as a new active material for microbolometer-based applications.

Thin-film rechargeable lithium batteries

NASA Astrophysics Data System (ADS)

Dudney, N. J.; Bates, J. B.; Lubben, D.

1994-11-01

Small thin-film rechargeable cells have been fabricated with a lithium phosphorus oxynitride electrolyte, Li metal anode, and Li(1-x)Mn2O4 as the cathode film. The cathode films were fabricated by several different techniques resulting in both crystalline and amorphous films. These were compared by observing the cell discharge behavior. Estimates have been made for the scale-up of such a thin-film battery to meet the specifications for the electric vehicle application. The specific energy, energy density, and cycle life are expected to meet the USABC mid-term criteria. However, the areas of the thin-films needed to fabricate such a cell are very large. The required areas could be greatly reduced by operating the battery at temperatures near 100 C or by enhancing the lithium ion transport rate in the cathode material.

Positron annihilation studies of vacancy related defects in ceramic and thin film Pb(Zr,Ti)O3 materials

NASA Astrophysics Data System (ADS)

Keeble, D. J.; Krishnan, A.; Umlor, M. T.; Lynn, K. G.; Warren, W. L.; Dimos, D.; Tuttle, B. A.

Preliminary positron annihilation studies of ceramic and thin film Pb(Zr,Ti)O3 (PZT) materials have been completed. This paper examines effects of processing conditions on vacancy related defects. Positron lifetime measurements on bulk PLZT plates showed an increase in positron trapping to a defect state with increasing grain size consistent with trapping to lead vacancy related defects formed through lead oxide loss during processing. Variable energy positron beam measurements were completed on bulk PLZT plates, sol-gel PZT thin films, and laser ablated PLZT thin films. Films processed in a reduced oxygen atmosphere were found to give a higher S-parameter, due to an increase in concentration of neutral or negatively charged vacancy type defects, compared with material processed in an oxidizing ambient.

A molecular scale perspective: Monte Carlo simulation for rupturing of ultra thin polymer film melts

NASA Astrophysics Data System (ADS)

Singh, Satya Pal

2017-04-01

Monte Carlo simulation has been performed to study the rupturing process of thin polymer film under strong confinement. The change in mean square displacement; pair correlation function; density distribution; average bond length and microscopic viscosity are sampled by varying the molecular interaction parameters such as the strength and the equilibrium positions of the bonding, non-bonding potentials and the sizes of the beads. The variation in mean square angular displacement χθ = [ < Δθ2 > - < Δθ>2 ] fits very well to a function of type y (t) = A + B *e-t/τ. This may help to study the viscous properties of the films and its dependence on different parameters. The ultra thin film annealed at high temperature gets ruptured and holes are created in the film mimicking spinodal dewetting. The pair correlation function and density profile reveal rich information about the equilibrium structure of the film. The strength and equilibrium bond length of finite extensible non-linear elastic potential (FENE) and non-bonding Morse potential have clear impact on microscopic rupturing of the film. The beads show Rouse or repetition motion forming rim like structures near the holes created inside the film. The higher order interaction as dipole-quadrupole may get prominence under strong confinement. The enhanced excluded volume interaction under strong confinement may overlap with the molecular dispersion forces. It can work to reorganize the molecules at the bottom of the scale and can imprint its signature in complex patterns evolved.

Combinatorial screening of halide perovskite thin films and solar cells by mask-defined IR laser molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Kawashima, Kazuhiro; Okamoto, Yuji; Annayev, Orazmuhammet; Toyokura, Nobuo; Takahashi, Ryota; Lippmaa, Mikk; Itaka, Kenji; Suzuki, Yoshikazu; Matsuki, Nobuyuki; Koinuma, Hideomi

2017-12-01

As an extension of combinatorial molecular layer epitaxy via ablation of perovskite oxides by a pulsed excimer laser, we have developed a laser molecular beam epitaxy (MBE) system for parallel integration of nano-scaled thin films of organic-inorganic hybrid materials. A pulsed infrared (IR) semiconductor laser was adopted for thermal evaporation of organic halide (A-site: CH3NH3I) and inorganic halide (B-site: PbI2) powder targets to deposit repeated A/B bilayer films where the thickness of each layer was controlled on molecular layer scale by programming the evaporation IR laser pulse number, length, or power. The layer thickness was monitored with an in situ quartz crystal microbalance and calibrated against ex situ stylus profilometer measurements. A computer-controlled movable mask system enabled the deposition of combinatorial thin film libraries, where each library contains a vertically homogeneous film with spatially programmable A- and B-layer thicknesses. On the composition gradient film, a hole transport Spiro-OMeTAD layer was spin-coated and dried followed by the vacuum evaporation of Ag electrodes to form the solar cell. The preliminary cell performance was evaluated by measuring I-V characteristics at seven different positions on the 12.5 mm × 12.5 mm combinatorial library sample with seven 2 mm × 4 mm slits under a solar simulator irradiation. The combinatorial solar cell library clearly demonstrated that the energy conversion efficiency sharply changes from nearly zero to 10.2% as a function of the illumination area in the library. The exploration of deposition parameters for obtaining optimum performance could thus be greatly accelerated. Since the thickness ratio of PbI2 and CH3NH3I can be freely chosen along the shadow mask movement, these experiments show the potential of this system for high-throughput screening of optimum chemical composition in the binary film library and application to halide perovskite solar cell.

Combinatorial screening of halide perovskite thin films and solar cells by mask-defined IR laser molecular beam epitaxy

PubMed Central

Kawashima, Kazuhiro; Okamoto, Yuji; Annayev, Orazmuhammet; Toyokura, Nobuo; Takahashi, Ryota; Lippmaa, Mikk; Itaka, Kenji; Suzuki, Yoshikazu; Matsuki, Nobuyuki; Koinuma, Hideomi

2017-01-01

Abstract As an extension of combinatorial molecular layer epitaxy via ablation of perovskite oxides by a pulsed excimer laser, we have developed a laser molecular beam epitaxy (MBE) system for parallel integration of nano-scaled thin films of organic–inorganic hybrid materials. A pulsed infrared (IR) semiconductor laser was adopted for thermal evaporation of organic halide (A-site: CH3NH3I) and inorganic halide (B-site: PbI2) powder targets to deposit repeated A/B bilayer films where the thickness of each layer was controlled on molecular layer scale by programming the evaporation IR laser pulse number, length, or power. The layer thickness was monitored with an in situ quartz crystal microbalance and calibrated against ex situ stylus profilometer measurements. A computer-controlled movable mask system enabled the deposition of combinatorial thin film libraries, where each library contains a vertically homogeneous film with spatially programmable A- and B-layer thicknesses. On the composition gradient film, a hole transport Spiro-OMeTAD layer was spin-coated and dried followed by the vacuum evaporation of Ag electrodes to form the solar cell. The preliminary cell performance was evaluated by measuring I-V characteristics at seven different positions on the 12.5 mm × 12.5 mm combinatorial library sample with seven 2 mm × 4 mm slits under a solar simulator irradiation. The combinatorial solar cell library clearly demonstrated that the energy conversion efficiency sharply changes from nearly zero to 10.2% as a function of the illumination area in the library. The exploration of deposition parameters for obtaining optimum performance could thus be greatly accelerated. Since the thickness ratio of PbI2 and CH3NH3I can be freely chosen along the shadow mask movement, these experiments show the potential of this system for high-throughput screening of optimum chemical composition in the binary film library and application to halide perovskite solar cell. PMID

Combinatorial screening of halide perovskite thin films and solar cells by mask-defined IR laser molecular beam epitaxy.

PubMed

Kawashima, Kazuhiro; Okamoto, Yuji; Annayev, Orazmuhammet; Toyokura, Nobuo; Takahashi, Ryota; Lippmaa, Mikk; Itaka, Kenji; Suzuki, Yoshikazu; Matsuki, Nobuyuki; Koinuma, Hideomi

2017-01-01

As an extension of combinatorial molecular layer epitaxy via ablation of perovskite oxides by a pulsed excimer laser, we have developed a laser molecular beam epitaxy (MBE) system for parallel integration of nano-scaled thin films of organic-inorganic hybrid materials. A pulsed infrared (IR) semiconductor laser was adopted for thermal evaporation of organic halide (A-site: CH 3 NH 3 I) and inorganic halide (B-site: PbI 2 ) powder targets to deposit repeated A/B bilayer films where the thickness of each layer was controlled on molecular layer scale by programming the evaporation IR laser pulse number, length, or power. The layer thickness was monitored with an in situ quartz crystal microbalance and calibrated against ex situ stylus profilometer measurements. A computer-controlled movable mask system enabled the deposition of combinatorial thin film libraries, where each library contains a vertically homogeneous film with spatially programmable A- and B-layer thicknesses. On the composition gradient film, a hole transport Spiro-OMeTAD layer was spin-coated and dried followed by the vacuum evaporation of Ag electrodes to form the solar cell. The preliminary cell performance was evaluated by measuring I - V characteristics at seven different positions on the 12.5 mm × 12.5 mm combinatorial library sample with seven 2 mm × 4 mm slits under a solar simulator irradiation. The combinatorial solar cell library clearly demonstrated that the energy conversion efficiency sharply changes from nearly zero to 10.2% as a function of the illumination area in the library. The exploration of deposition parameters for obtaining optimum performance could thus be greatly accelerated. Since the thickness ratio of PbI 2 and CH 3 NH 3 I can be freely chosen along the shadow mask movement, these experiments show the potential of this system for high-throughput screening of optimum chemical composition in the binary film library and application to halide perovskite solar cell.

Emergent Topological Phenomena in Thin Films of Pyrochlore Iridates

NASA Astrophysics Data System (ADS)

Yang, Bohm-Jung; Nagaosa, Naoto

2014-06-01

Because of the recent development of thin film and artificial superstructure growth techniques, it is possible to control the dimensionality of the system, smoothly between two and three dimensions. In this Letter we unveil the dimensional crossover of emergent topological phenomena in correlated topological materials. In particular, by focusing on the thin film of pyrochlore iridate antiferromagnets grown along the [111] direction, we demonstrate that the thin film can have a giant anomalous Hall conductance, proportional to the thickness of the film, even though there is no Hall effect in 3D bulk material. Moreover, in the case of ultrathin films, a quantized anomalous Hall conductance can be observed, despite the fact that the system is an antiferromagnet. In addition, we uncover the emergence of a new topological phase, the nontrivial topological properties of which are hidden in the bulk insulator and manifest only in thin films. This shows that the thin film of correlated topological materials is a new platform to search for unexplored novel topological phenomena.

Thin film lithium-based batteries and electrochromic devices fabricated with nanocomposite electrode materials

DOEpatents

Gillaspie, Dane T; Lee, Se-Hee; Tracy, C. Edwin; Pitts, John Roland

2014-02-04

Thin-film lithium-based batteries and electrochromic devices (10) are fabricated with positive electrodes (12) comprising a nanocomposite material composed of lithiated metal oxide nanoparticles (40) dispersed in a matrix composed of lithium tungsten oxide.

Femtosecond laser ablation-based mass spectrometry. An ideal tool for stoichiometric analysis of thin films

DOE PAGES

LaHaye, Nicole L.; Kurian, Jose; Diwakar, Prasoon K.; ...

2015-08-19

An accurate and routinely available method for stoichiometric analysis of thin films is a desideratum of modern materials science where a material’s properties depend sensitively on elemental composition. We thoroughly investigated femtosecond laser ablation-inductively coupled plasma-mass spectrometry (fs-LA-ICP-MS) as an analytical technique for determination of the stoichiometry of thin films down to the nanometer scale. The use of femtosecond laser ablation allows for precise removal of material with high spatial and depth resolution that can be coupled to an ICP-MS to obtain elemental and isotopic information. We used molecular beam epitaxy-grown thin films of LaPd (x)Sb 2 and T´-La 2CuOmore » 4 to demonstrate the capacity of fs-LA-ICP-MS for stoichiometric analysis and the spatial and depth resolution of the technique. Here we demonstrate that the stoichiometric information of thin films with a thickness of ~10 nm or lower can be determined. Furthermore, our results indicate that fs-LA-ICP-MS provides precise information on the thin film-substrate interface and is able to detect the interdiffusion of cations.« less

Solid-State Solvation and Enhanced Exciton Diffusion in Doped Organic Thin Films under Mechanical Pressure.

PubMed

Chang, Wendi; Akselrod, Gleb M; Bulović, Vladimir

2015-04-28

Direct modification of exciton energy has been previously used to optimize the operation of organic optoelectronic devices. One demonstrated method for exciton energy modification is through the use of the solvent dielectric effects in doped molecular films. To gain a deeper appreciation of the underlying physical mechanisms, in this work we test the solid-state solvation effect in molecular thin films under applied external pressure. We observe that external mechanical pressure increases dipole-dipole interactions, leading to shifts in the Frenkel exciton energy and enhancement of the time-resolved spectral red shift associated with the energy-transfer-mediated exciton diffusion. Measurements are performed on host:dopant molecular thin films, which show bathochromic shifts in photoluminescence (PL) under increasing pressure. This is in agreement with a simple solvation theory model of exciton energetics with a fitting parameter based on the mechanical properties of the host matrix material. We measure no significant change in exciton lifetime with increasing pressure, consistent with unchanged aggregation in molecular films under compression. However, we do observe an increase in exciton spectral thermalization rate for compressed molecular films, indicating enhanced exciton diffusion for increased dipole-dipole interactions under pressure. The results highlight the contrast between molecular energy landscapes obtained when dipole-dipole interactions are increased by the pressure technique versus the conventional dopant concentration variation methods, which can lead to extraneous effects such as aggregation at higher doping concentrations. The present work demonstrates the use of pressure-probing techniques in studying energy disorder and exciton dynamics in amorphous molecular thin films.

Solid-State Solvation and Enhanced Exciton Diffusion in Doped Organic Thin Films under Mechanical Pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Wendi; Akselrod, Gleb M.; Bulović, Vladimir

2015-04-28

Direct modification of exciton energy has been previously used to optimize the operation of organic optoelectronic devices. One demonstrated method for exciton energy modification is through the use of the solvent dielectric effects in doped molecular films. To gain a deeper appreciation of the underlying physical mechanisms, in this work we test the solid-state solvation effect in molecular thin films under applied external pressure. We observe that external mechanical pressure increases dipole–dipole interactions, leading to shifts in the Frenkel exciton energy and enhancement of the time-resolved spectral red shift associated with the energy-transfer-mediated exciton diffusion. Measurements are performed on host:dopantmore » molecular thin films, which show bathochromic shifts in photoluminescence (PL) under increasing pressure. This is in agreement with a simple solvation theory model of exciton energetics with a fitting parameter based on the mechanical properties of the host matrix material. We measure no significant change in exciton lifetime with increasing pressure, consistent with unchanged aggregation in molecular films under compression. However, we do observe an increase in exciton spectral thermalization rate for compressed molecular films, indicating enhanced exciton diffusion for increased dipole–dipole interactions under pressure. The results highlight the contrast between molecular energy landscapes obtained when dipole–dipole interactions are increased by the pressure technique versus the conventional dopant concentration variation methods, which can lead to extraneous effects such as aggregation at higher doping concentrations. The present work demonstrates the use of pressure-probing techniques in studying energy disorder and exciton dynamics in amorphous molecular thin films.« less

Nanostructured manganese oxide thin films as electrode material for supercapacitors

NASA Astrophysics Data System (ADS)

Xia, Hui; Lai, Man On; Lu, Li

2011-01-01

Electrochemical capacitors, also called supercapacitors, are alternative energy storage devices, particularly for applications requiring high power densities. Recently, manganese oxides have been extensively evaluated as electrode materials for supercapacitors due to their low cost, environmental benignity, and promising supercapacitive performance. In order to maximize the utilization of manganese oxides as the electrode material for the supercapacitors and improve their supercapacitive performance, the nanostructured manganese oxides have therefore been developed. This paper reviews the synthesis of the nanostructured manganese oxide thin films by different methods and the supercapacitive performance of different nanostructures.

Epitaxial thin film growth in outer space

NASA Technical Reports Server (NTRS)

Ignatiev, Alex; Chu, C. W.

1988-01-01

A new concept for materials processing in space exploits the ultravacuum component of space for thin-film epitaxial growth. The unique LEO space environment is expected to yield 10-ftorr or better pressures, semiinfinite pumping speeds, and large ultravacuum volume (about 100 cu m) without walls. These space ultravacuum properties promise major improvement in the quality, unique nature, and throughput of epitaxially grown materials, including semiconductors, magnetic materials, and thin-film high-temperature superconductors.

Thin film ferroelectric electro-optic memory

NASA Technical Reports Server (NTRS)

Thakoor, Sarita (Inventor); Thakoor, Anilkumar P. (Inventor)

1993-01-01

An electrically programmable, optically readable data or memory cell is configured from a thin film of ferroelectric material, such as PZT, sandwiched between a transparent top electrode and a bottom electrode. The output photoresponse, which may be a photocurrent or photo-emf, is a function of the product of the remanent polarization from a previously applied polarization voltage and the incident light intensity. The cell is useful for analog and digital data storage as well as opto-electric computing. The optical read operation is non-destructive of the remanent polarization. The cell provides a method for computing the product of stored data and incident optical data by applying an electrical signal to store data by polarizing the thin film ferroelectric material, and then applying an intensity modulated optical signal incident onto the thin film material to generate a photoresponse therein related to the product of the electrical and optical signals.

Thin-film metal hydrides.

PubMed

Remhof, Arndt; Borgschulte, Andreas

2008-12-01

The goal of the medieval alchemist, the chemical transformation of common metals into nobel metals, will forever be a dream. However, key characteristics of metals, such as their electronic band structure and, consequently, their electric, magnetic and optical properties, can be tailored by controlled hydrogen doping. Due to their morphology and well-defined geometry with flat, coplanar surfaces/interfaces, novel phenomena may be observed in thin films. Prominent examples are the eye-catching hydrogen switchable mirror effect, the visualization of solid-state diffusion and the formation of complex surface morphologies. Thin films do not suffer as much from embrittlement and/or decrepitation as bulk materials, allowing the study of cyclic absorption and desorption. Therefore, thin-metal hydride films are used as model systems to study metal-insulator transitions, for high throughput combinatorial research or they may be used as indicator layers to study hydrogen diffusion. They can be found in technological applications as hydrogen sensors, in electrochromic and thermochromic devices. In this review, we discuss the effect of hydrogen loading of thin niobium and yttrium films as archetypical examples of a transition metal and a rare earth metal, respectively. Our focus thereby lies on the hydrogen induced changes of the electronic structure and the morphology of the thin films, their optical properties, the visualization and the control of hydrogen diffusion and on the study of surface phenomena and catalysis.

Microstructure and ferroelectricity of BaTiO3 thin films on Si for integrated photonics

NASA Astrophysics Data System (ADS)

Kormondy, Kristy J.; Popoff, Youri; Sousa, Marilyne; Eltes, Felix; Caimi, Daniele; Rossell, Marta D.; Fiebig, Manfred; Hoffmann, Patrik; Marchiori, Chiara; Reinke, Michael; Trassin, Morgan; Demkov, Alexander A.; Fompeyrine, Jean; Abe, Stefan

2017-02-01

Significant progress has been made in integrating novel materials into silicon photonic structures in order to extend the functionality of photonic circuits. One of these promising optical materials is BaTiO3 or barium titanate (BTO) that exhibits a very large Pockels coefficient as required for high-speed light modulators. However, all previous demonstrations show a noticable reduction of the Pockels effect in BTO thin films deposited on silicon substrates compared to BTO bulk crystals. Here, we report on the strong dependence of the Pockels effect in BTO thin films on their microstructure, and provide guidelines on how to engineer thin films with strong electro-optic response. We employ several deposition methods such as molecular beam epitaxy and chemical vapor deposition to realize BTO thin films with different morphology and crystalline structure. While a linear electro-optic response is present even in porous, polycrystalline BTO thin films with an effective Pockels coefficient r eff = 6 pm V-1, it is maximized for dense, tetragonal, epitaxial BTO films (r eff = 140 pm V-1). By identifying the key structural predictors of electro-optic response in BTO/Si, we provide a roadmap to fully exploit the linear electro-optic effect in novel hybrid oxide/semiconductor nanophotonic devices.

Patterns and conformations in molecularly thin films

NASA Astrophysics Data System (ADS)

Basnet, Prem B.

Molecularly thin films have been a subject of great interest for the last several years because of their large variety of industrial applications ranging from micro-electronics to bio-medicine. Additionally, molecularly thin films can be used as good models for biomembrane and other systems where surfaces are critical. Many different kinds of molecules can make stable films. My research has considered three such molecules: a polymerizable phospholipid, a bent-core molecules, and a polymer. One common theme of these three molecules is chirality. The phospolipid molecules studied here are strongly chiral, which can be due to intrinsically chiral centers on the molecules and also due to chiral conformations. We find that these molecules give rise to chiral patterns. Bent-core molecules are not intrinsically chiral, but individual molecules and groups of molecules can show chiral structures, which can be changed by surface interactions. One major, unconfirmed hypothesis for the polymer conformation at surface is that it forms helices, which would be chiral. Most experiments were carried out at the air/water interface, in what are called Langmuir films. Our major tools for studying these films are Brewster Angle Microscopy (BAM) coupled with the thermodynamic information that can be deduced from surface pressure isotherms. Phospholipids are one of the important constituents of liposomes -- a spherical vesicle com-posed of a bilayer membrane, typically composed of a phospholipid and cholesterol bilayer. The application of liposomes in drug delivery is well-known. Crumpling of vesicles of polymerizable phospholipids has been observed. With BAM, on Langmuir films of such phospholipids, we see novel spiral/target patterns during compression. We have found that both the patterns and the critical pressure at which they formed depend on temperature (below the transition to a i¬‘uid layer). Bent-core liquid crystals, sometimes knows as banana liquid crystals, have drawn

High-throughput characterization of stresses in thin film materials libraries using Si cantilever array wafers and digital holographic microscopy.

PubMed

Lai, Y W; Hamann, S; Ehmann, M; Ludwig, A

2011-06-01

We report the development of an advanced high-throughput stress characterization method for thin film materials libraries sputter-deposited on micro-machined cantilever arrays consisting of around 1500 cantilevers on 4-inch silicon-on-insulator wafers. A low-cost custom-designed digital holographic microscope (DHM) is employed to simultaneously monitor the thin film thickness, the surface topography and the curvature of each of the cantilevers before and after deposition. The variation in stress state across the thin film materials library is then calculated by Stoney's equation based on the obtained radii of curvature of the cantilevers and film thicknesses. DHM with nanometer-scale out-of-plane resolution allows stress measurements in a wide range, at least from several MPa to several GPa. By using an automatic x-y translation stage, the local stresses within a 4-inch materials library are mapped with high accuracy within 10 min. The speed of measurement is greatly improved compared with the prior laser scanning approach that needs more than an hour of measuring time. A high-throughput stress measurement of an as-deposited Fe-Pd-W materials library was evaluated for demonstration. The fast characterization method is expected to accelerate the development of (functional) thin films, e.g., (magnetic) shape memory materials, whose functionality is greatly stress dependent. © 2011 American Institute of Physics

Chemical Fabrication Used to Produce Thin-Film Materials for High Power-to- Weight-Ratio Space Photovoltaic Arrays

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Rybicki, George C.; Raffaelle, Ryne P.; Harris, Jerry D.; Hehemann, David G.; Junek, William; Gorse, Joseph; Thompson, Tracy L.; Hollingsworth, Jennifer A.; Buhro, William E.

2000-01-01

The key to achieving high specific power (watts per kilogram) space solar arrays is the development of a high-efficiency, thin-film solar cell that can be fabricated directly on a flexible, lightweight, space-qualified durable substrate such as Kapton (DuPont) or other polyimide or suitable polymer film. Cell efficiencies approaching 20 percent at AM0 (air mass zero) are required. Current thin-film cell fabrication approaches are limited by either (1) the ultimate efficiency that can be achieved with the device material and structure or (2) the requirement for high-temperature deposition processes that are incompatible with all presently known flexible polyimide or other polymer substrate materials. Cell fabrication processes must be developed that will produce high-efficiency cells at temperatures below 400 degrees Celsius, and preferably below 300 degress Celsius to minimize the problems associated with the difference between the coefficients of thermal expansion of the substrate and thin-film solar cell and/or the decomposition of the substrate.

A proposal for epitaxial thin film growth in outer space

NASA Technical Reports Server (NTRS)

Ignatiev, Alex; Chu, C. W.

1988-01-01

A new concept for materials processing in space exploits the ultravacuum component of space for thin film epitaxial growth. The unique low earth orbit space environment is expected to yield 10 to the -14th torr or better pressures, semiinfinite pumping speeds, and large ultravacuum volume without walls. These space ultravacuum properties promise major improvement in the quality, unique nature, and the throughput of epitaxially grown materials. Advanced thin film materials to be epitaxially grown in space include semiconductors, magnetic materials, and thin film high temperature superconductors.

Solution processable semiconductor thin films: Correlation between morphological, structural, optical and charge transport properties

NASA Astrophysics Data System (ADS)

Isik, Dilek

This Ph.D. thesis is a result of multidisciplinary research bringing together fundamental concepts in thin film engineering, materials science, materials processing and characterization, electrochemistry, microfabrication, and device physics. Experiments were conducted by tackling scientific problems in the field of thin films and interfaces, with the aim to correlate the morphology, crystalline structure, electronic structure of thin films with the functional properties of the films and the performances of electronic devices based thereon. Furthermore, novel strategies based on interfacial phenomena at electrolyte/thin film interfaces were explored and exploited to control the electrical conductivity of the thin films. Three main chemical systems were the object of the studies performed during this Ph.D., two types of organic semiconductors (azomethine-based oligomers and polymers and soluble pentacene derivatives) and one metal oxide semiconductor (tungsten trioxide, WO3). To explore the morphological properties of the thin films, atomic force microscopy was employed. The morphological properties were further investigated by hyperspectral fluorescence microscopy and tentatively correlated to the charge transport properties of the films. X-ray diffraction (Grazing incidence XRD, GIXRD) was used to investigate the crystallinity of the film and the effect of the heat treatment on such crystallinity, as well as to understand the molecular arrangement of the organic molecules in the thin film. The charge transport properties of the films were evaluated in thin film transistor configuration. For electrolyte gated thin film transistors, time dependent transient measurements were conducted, in parallel to more conventional transistor characterizations, to explore the specific effects played on the gating by the anion and cation constituting the electrolyte. The capacitances of the electrical double layers at the electrolyte/WO3 interface were obtained from

Polythiophene thin films by surface-initiated polymerization: Mechanistic and structural studies

DOE PAGES

Youm, Sang Gil; Hwang, Euiyong; Chavez, Carlos A.; ...

2016-06-15

The ability to control nanoscale morphology and molecular organization in organic semiconducting polymer thin films is an important prerequisite for enhancing the efficiency of organic thin-film devices including organic light-emitting and photovoltaic devices. The current “top-down” paradigm for making such devices is based on utilizing solution-based processing (e.g., spin-casting) of soluble semiconducting polymers. This approach typically provides only modest control over nanoscale molecular organization and polymer chain alignment. A promising alternative to using solutions of presynthesized semiconducting polymers pursues instead a “bottom-up” approach to prepare surface-grafted semiconducting polymer thin films by surface-initiated polymerization of small-molecule monomers. Herein, we describe themore » development of an efficient method to prepare polythiophene thin films utilizing surface-initiated Kumada catalyst transfer polymerization. In this study, we provided evidence that the surface-initiated polymerization occurs by the highly robust controlled (quasi-“living”) chain-growth mechanism. Further optimization of this method enabled reliable preparation of polythiophene thin films with thickness up to 100 nm. Extensive structural studies of the resulting thin films using X-ray and neutron scattering methods as well as ultraviolet photoemission spectroscopy revealed detailed information on molecular organization and the bulk morphology of the films, and enabled further optimization of the polymerization protocol. One of the remarkable findings was that surface-initiated polymerization delivers polymer thin films showing complex molecular organization, where polythiophene chains assemble into lateral crystalline domains of about 3.2 nm size, with individual polymer chains folded to form in-plane aligned and densely packed oligomeric segments (7-8 thiophene units per each segment) within each domain. Achieving such a complex mesoscale

Ion Beam Assisted Deposition of Thin Epitaxial GaN Films.

PubMed

Rauschenbach, Bernd; Lotnyk, Andriy; Neumann, Lena; Poppitz, David; Gerlach, Jürgen W

2017-06-23

The assistance of thin film deposition with low-energy ion bombardment influences their final properties significantly. Especially, the application of so-called hyperthermal ions (energy <100 eV) is capable to modify the characteristics of the growing film without generating a large number of irradiation induced defects. The nitrogen ion beam assisted molecular beam epitaxy (ion energy <25 eV) is used to deposit GaN thin films on (0001)-oriented 6H-SiC substrates at 700 °C. The films are studied in situ by reflection high energy electron diffraction, ex situ by X-ray diffraction, scanning tunnelling microscopy, and high-resolution transmission electron microscopy. It is demonstrated that the film growth mode can be controlled by varying the ion to atom ratio, where 2D films are characterized by a smooth topography, a high crystalline quality, low biaxial stress, and low defect density. Typical structural defects in the GaN thin films were identified as basal plane stacking faults, low-angle grain boundaries forming between w-GaN and z-GaN and twin boundaries. The misfit strain between the GaN thin films and substrates is relieved by the generation of edge dislocations in the first and second monolayers of GaN thin films and of misfit interfacial dislocations. It can be demonstrated that the low-energy nitrogen ion assisted molecular beam epitaxy is a technique to produce thin GaN films of high crystalline quality.

Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

NASA Astrophysics Data System (ADS)

Chi, Su (Ike); Farias, Stephen; Cammarata, Robert

2013-03-01

Tellurium alloys are characterized by their high performance thermoelectric properties and recent research has shown nanostructured tellurium alloys display even greater performance than bulk equivalents. Increased thermoelectric efficiency of nanostructured materials have led to significant interests in developing thin film and nanowire structures. Here, we report on the first successful electrodeposition of lanthanum telluride thin films and nanowires. The electrodeposition of lanthanum telluride thin films is performed in ionic liquids at room temperature. The synthesis of nanowires involves electrodepositing lanthanum telluride arrays into anodic aluminum oxide (AAO) nanoporous membranes. These novel procedures can serve as an alternative means of simple, inexpensive and laboratory-environment friendly methods to synthesize nanostructured thermoelectric materials. The thermoelectric properties of thin films and nanowires will be presented to compare to current state-of-the-art thermoelectric materials. The morphologies and chemical compositions of the deposited films and nanowires are characterized using SEM and EDAX analysis.

Tunable Affinity and Molecular Architecture Lead to Diverse Self-Assembled Supramolecular Structures in Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Chih-Hao; Dong, Xue-Hui; Lin, Zhiwei

2015-12-03

The self-assembly behaviors of specifically designed giant surfactants are systematically studied in thin films using grazing incident X-ray and transmission electron microscopy (TEM), focusing on the effects of head surface functionalities and molecular architectures on nanostructure formation. Two molecular nanoparticles (MNPs) with different affinities, i.e., hydrophilic carboxylic acid functionalized [60]fullerene (AC60) and omniphobic fluorinated polyhedral oligomeric silsesquioxane (FPOSS), are utilized as heads of the giant surfactants. By covalently tethering these functional MNPs onto the chain end or the junction point of polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer, linear and star-like giant surfactants possess distinct molecular architectures are constructed. With fixed lengthmore » of the PEO block, the molecular weight change of the PS block originates the phase formation and transition. Due to the distinct affinity, the AC60-based giant surfactants form two-component morphologies, while three-component morphologies are found in the FPOSS-based ones. A PS block stretching parameter is introduced to characterize the PS chain conformation in different morphologies. The highly diverse self-assembly behaviors and the tunable dimensions in thin films suggest the giant surfactants could be a promising and robust platform for nanolithography applications.« less

Thin Film Ceramic Strain Sensor Development for Harsh Environments: Identification of Candidate Thin Film Ceramics to Test for Viability for Static Strain Sensor Development

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Hunter, Gary W.

2006-01-01

The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in propulsion system applications. In order to have a more passive method of negating changes of resistance due to temperature, an effort is underway at NASA GRC to develop high temperature thin film ceramic static strain gauges for application in turbine engines, specifically in the fan and compressor modules on blades. Other applications include on aircraft hot section structures and on thermal protection systems. The near-term interim goal of this research effort was to identify candidate thin film ceramic sensor materials to test for viability and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. This goal was achieved by a thorough literature search for ceramics that have the potential for application as high temperature thin film strain gauges, reviewing potential candidate materials for chemical & physical compatibility with NASA GRC's microfabrication procedures and substrates.

Titanium dioxide thin films by atomic layer deposition: a review

NASA Astrophysics Data System (ADS)

Niemelä, Janne-Petteri; Marin, Giovanni; Karppinen, Maarit

2017-09-01

Within its rich phase diagram titanium dioxide is a truly multifunctional material with a property palette that has been shown to span from dielectric to transparent-conducting characteristics, in addition to the well-known catalytic properties. At the same time down-scaling of microelectronic devices has led to an explosive growth in research on atomic layer deposition (ALD) of a wide variety of frontier thin-film materials, among which TiO2 is one of the most popular ones. In this topical review we summarize the advances in research of ALD of titanium dioxide starting from the chemistries of the over 50 different deposition routes developed for TiO2 and the resultant structural characteristics of the films. We then continue with the doped ALD-TiO2 thin films from the perspective of dielectric, transparent-conductor and photocatalytic applications. Moreover, in order to cover the latest trends in the research field, both the variously constructed TiO2 nanostructures enabled by ALD and the Ti-based hybrid inorganic-organic films grown by the emerging ALD/MLD (combined atomic/molecular layer deposition) technique are discussed.

Mesoscale simulations of confined Nafion thin films.

PubMed

Vanya, P; Sharman, J; Elliott, J A

2017-12-07

The morphology and transport properties of thin films of the ionomer Nafion, with thicknesses on the order of the bulk cluster size, have been investigated as a model system to explain the anomalous behaviour of catalyst/electrode-polymer interfaces in membrane electrode assemblies. We have employed dissipative particle dynamics (DPD) to investigate the interaction of water and fluorocarbon chains, with carbon and quartz as confining materials, for a wide range of operational water contents and film thicknesses. We found confinement-induced clustering of water perpendicular to the thin film. Hydrophobic carbon forms a water depletion zone near the film interface, whereas hydrophilic quartz results in a zone with excess water. There are, on average, oscillating water-rich and fluorocarbon-rich regions, in agreement with experimental results from neutron reflectometry. Water diffusivity shows increasing directional anisotropy of up to 30% with decreasing film thickness, depending on the hydrophilicity of the confining material. A percolation analysis revealed significant differences in water clustering and connectivity with the confining material. These findings indicate the fundamentally different nature of ionomer thin films, compared to membranes, and suggest explanations for increased ionic resistances observed in the catalyst layer.

Mesoscale simulations of confined Nafion thin films

NASA Astrophysics Data System (ADS)

Vanya, P.; Sharman, J.; Elliott, J. A.

2017-12-01

The morphology and transport properties of thin films of the ionomer Nafion, with thicknesses on the order of the bulk cluster size, have been investigated as a model system to explain the anomalous behaviour of catalyst/electrode-polymer interfaces in membrane electrode assemblies. We have employed dissipative particle dynamics (DPD) to investigate the interaction of water and fluorocarbon chains, with carbon and quartz as confining materials, for a wide range of operational water contents and film thicknesses. We found confinement-induced clustering of water perpendicular to the thin film. Hydrophobic carbon forms a water depletion zone near the film interface, whereas hydrophilic quartz results in a zone with excess water. There are, on average, oscillating water-rich and fluorocarbon-rich regions, in agreement with experimental results from neutron reflectometry. Water diffusivity shows increasing directional anisotropy of up to 30% with decreasing film thickness, depending on the hydrophilicity of the confining material. A percolation analysis revealed significant differences in water clustering and connectivity with the confining material. These findings indicate the fundamentally different nature of ionomer thin films, compared to membranes, and suggest explanations for increased ionic resistances observed in the catalyst layer.

Yttrium Iron Garnet Thin Films with Very Low Damping Obtained by Recrystallization of Amorphous Material

PubMed Central

Hauser, Christoph; Richter, Tim; Homonnay, Nico; Eisenschmidt, Christian; Qaid, Mohammad; Deniz, Hakan; Hesse, Dietrich; Sawicki, Maciej; Ebbinghaus, Stefan G.; Schmidt, Georg

2016-01-01

We have investigated recrystallization of amorphous Yttrium Iron Garnet (YIG) by annealing in oxygen atmosphere. Our findings show that well below the melting temperature the material transforms into a fully epitaxial layer with exceptional quality, both structural and magnetic. In ferromagnetic resonance (FMR) ultra low damping and extremely narrow linewidth can be observed. For a 56 nm thick layer a damping constant of α = (6.15 ± 1.50) · 10−5 is found and the linewidth at 9.6 GHz is as small as 1.30 ± 0.05 Oe which are the lowest values for PLD grown thin films reported so far. Even for a 20 nm thick layer a damping constant of α = (7.35 ± 1.40) · 10−5 is found which is the lowest value for ultrathin films published so far. The FMR linewidth in this case is 3.49 ± 0.10 Oe at 9.6 GHz. Our results not only present a method of depositing thin film YIG of unprecedented quality but also open up new options for the fabrication of thin film complex oxides or even other crystalline materials. PMID:26860816

Method for making surfactant-templated, high-porosity thin films

DOEpatents

Brinker, C. Jeffrey; Lu, Yunfeng; Fan, Hongyou

2001-01-01

An evaporation-induced self-assembly method to prepare a surfactant-templated thin film by mixing a silica sol, a surfactant, and a hydrophobic polymer and then evaporating a portion of the solvent during coating onto a substrate and then heating to form a liquid-phase, thin film material with a porosity greater than approximately 50 percent. The high porosity thin films can have dielectric constants less than 2 to be suitable for applications requiring low-dielectric constants. An interstitial compound can be added to the mixture, with the interstitial compound either covalently bonded to the pores or physically entrapped within the porous structure. The selection of the interstitial compound provides a means for developing thin films for applications including membranes, sensors, low dielectric constant films, photonic materials and optical hosts.

Through a Window, Brightly: A Review of Selected Nanofabricated Thin-Film Platforms for Spectroscopy, Imaging, and Detection.

PubMed

Dwyer, Jason R; Harb, Maher

2017-09-01

We present a review of the use of selected nanofabricated thin films to deliver a host of capabilities and insights spanning bioanalytical and biophysical chemistry, materials science, and fundamental molecular-level research. We discuss approaches where thin films have been vital, enabling experimental studies using a variety of optical spectroscopies across the visible and infrared spectral range, electron microscopies, and related techniques such as electron energy loss spectroscopy, X-ray photoelectron spectroscopy, and single molecule sensing. We anchor this broad discussion by highlighting two particularly exciting exemplars: a thin-walled nanofluidic sample cell concept that has advanced the discovery horizons of ultrafast spectroscopy and of electron microscopy investigations of in-liquid samples; and a unique class of thin-film-based nanofluidic devices, designed around a nanopore, with expansive prospects for single molecule sensing. Free-standing, low-stress silicon nitride membranes are a canonical structural element for these applications, and we elucidate the fabrication and resulting features-including mechanical stability, optical properties, X-ray and electron scattering properties, and chemical nature-of this material in this format. We also outline design and performance principles and include a discussion of underlying material preparations and properties suitable for understanding the use of alternative thin-film materials such as graphene.

Structure and transport in organic semiconductor thin films

NASA Astrophysics Data System (ADS)

Vos, Sandra Elizabeth Fritz

Organic Semiconductors represent an exciting area of research due to their potential application in cheap and flexible electronics. In spite of the abundant interest in organic electronics the electronic transport mechanism remains poorly understood. Understanding the connection between molecular structure, crystal packing, intermolecular interactions and electronic delocalization is an important aspect of improving the transport properties of organics in thin film transistors (TFTs). In an organic thin film transistor, charge carrier transport is believed to occur within the first few monolayers of the organic material adjacent to the dielectric. It is therefore critical to understand the initial stages of film growth and molecular structure in these first few layers and relate this structure to electronic transport properties. The structure of organic films at the interface with an amorphous silicon dioxide ( a-SiO2) dielectric and how structure relates to transport in a TFT is the focus of this thesis. Pentacene films on a-SiO2 were extensively characterized with specular and in-plane X-ray diffraction, and CuKalpha1, and synchrotron radiation. The first layer of pentacene molecules adjacent to the a-SiO2 crystallized in a rectangular unit cell with the long axis of the molecules perpendicular to the substrate surface. Subsequent layers of pentacene crystallized in a slightly oblique in-plane unit cell that evolved as thickness was increased. The rectangular monolayer phase of pentacene did not persist when subsequent layers were deposited. Specular diffraction with Synchrotron radiation of a 160 A pentacene film (˜ 10 layers) revealed growth initiation of a bulk-like phase and persistence of the thin-film phase. Pentacene molecules were more tilted in the bulk-like phase and the in-plane unit cell was slightly more oblique. Pentacene grains began to grow randomly oriented with respect to the substrate surface (out-of-plane) in films near 650 A in thickness

Thin film photovoltaic device

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1982-01-01

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids.

Thin film photovoltaic device

DOEpatents

Catalano, A.W.; Bhushan, M.

1982-08-03

A thin film photovoltaic solar cell which utilizes a zinc phosphide semiconductor is of the homojunction type comprising an n-type conductivity region forming an electrical junction with a p-type region, both regions consisting essentially of the same semiconductor material. The n-type region is formed by treating zinc phosphide with an extrinsic dopant such as magnesium. The semiconductor is formed on a multilayer substrate which acts as an opaque contact. Various transparent contacts may be used, including a thin metal film of the same chemical composition as the n-type dopant or conductive oxides or metal grids. 5 figs.

Strain-induced phenomenon in complex oxide thin films

NASA Astrophysics Data System (ADS)

Haislmaier, Ryan

Complex oxide materials wield an immense spectrum of functional properties such as ferroelectricity, ferromagnetism, magnetoelectricity, optoelectricity, optomechanical, magnetoresistance, superconductivity, etc. The rich coupling between charge, spin, strain, and orbital degrees of freedom makes this material class extremely desirable and relevant for next generation electronic devices and technologies which are trending towards nanoscale dimensions. Development of complex oxide thin film materials is essential for realizing their integration into nanoscale electronic devices, where theoretically predicted multifunctional capabilities of oxides could add tremendous value. Employing thin film growth strategies such as epitaxial strain and heterostructure interface engineering can greatly enhance and even unlock novel material properties in complex oxides, which will be the main focus of this work. However, physically incorporating oxide materials into devices remains a challenge. While advancements in molecular beam epitaxy (MBE) of thin film oxide materials has led to the ability to grow oxide materials with atomic layer precision, there are still major limitations such as controlling stoichiometric compositions during growth as well as creating abrupt interfaces in multi-component layered oxide structures. The work done in this thesis addresses ways to overcome these limitations in order to harness intrinsic material phenomena. The development of adsorption-controlled stoichiometric growth windows of CaTiO3 and SrTiO3 thin film materials grown by hybrid MBE where Ti is supplied using metal-organic titanium tetraisopropoxide material is thoroughly outlined. These growth windows enable superior epitaxial strain-induced ferroelectric and dielectric properties to be accessed as demonstrated by chemical, structural, electrical, and optical characterization techniques. For tensile strained CaTiO3 and compressive strained SrTiO 3 films, the critical effects of

In-space fabrication of thin-film structures

NASA Technical Reports Server (NTRS)

Lippman, M. E.

1972-01-01

A conceptual study of physical vapor-deposition processes for in-space fabrication of thin-film structures is presented. Potential advantages of in-space fabrication are improved structural integrity and surface reflectivity of free-standing ultra-thin films and coatings. Free-standing thin-film structures can find use as photon propulsion devices (solar sails). Other applications of the concept involve free-standing shadow shields, or thermal control coatings of spacecraft surfaces. Use of expendables (such as booster and interstage structures) as source material for the physical vapor deposition process is considered. The practicability of producing thin, textured, aluminum films by physical vapor deposition and subsequent separation from a revolving substrate is demonstrated by laboratory experiments. Heating power requirement for the evaporation process is estimated for a specific mission.

Initial Study on Thin Film Preparation of Carbon Nanodots Composites as Luminescence Material

NASA Astrophysics Data System (ADS)

Iskandar, F.; Aimon, A. H.; Akmaluddin, A. R.; Nuryadin, B. W.; Abdullah, M.

2016-08-01

Nowadays, the developments of phosphors materials require elements without noble metals and simple production process. Carbon nanodots (C-dots) are one of phosphor materials with wide range of emission band, and high biocompatibility. In this research thin film carbon nanodots composite have been prepared by spin coating method. Prior deposition, powder carbon nanodots were synthesized from a mixture of commercial urea as the nitrogen sources and citric acid as a carbon source by using hydrothermal and microwave-assisted heating method. The prepared powder was dispersed in transparent epoxy resin and then coated on glass substrate. The photoluminescence result for sample with 0.035 g citric acid exhibited an intense, single, homogeneous and broad spectrum with yellowish emission upon excitation at 365 nm. The Fourier Transform Infrared Spectroscopy (FTIR) result showed the existences of C=C, C-H, C=O, N-H and O-H functional groups which confirmed the quality of the sample. Further, based on UV-Vis measurement, the prepared thin film was highly transparent (transmittance 90%) with estimated film thickness around 764 nm. This result may open an opportunity for optoelectronic devices.

Material engineering to fabricate rare earth erbium thin films for exploring nuclear energy sources

NASA Astrophysics Data System (ADS)

Banerjee, A.; Abhilash, S. R.; Umapathy, G. R.; Kabiraj, D.; Ojha, S.; Mandal, S.

2018-04-01

High vacuum evaporation and cold-rolling techniques to fabricate thin films of the rare earth lanthanide-erbium have been discussed in this communication. Cold rolling has been used for the first time to successfully fabricate films of enriched and highly expensive erbium metal with areal density in the range of 0.5-1.0 mg/cm2. The fabricated films were used as target materials in an advanced nuclear physics experiment. The experiment was designed to investigate isomeric states in the heavy nuclei mass region for exploring physics related to nuclear energy sources. The films fabricated using different techniques varied in thickness as well as purity. Methods to fabricate films with thickness of the order of 0.9 mg/cm2 were different than those of 0.4 mg/cm2 areal density. All the thin films were characterized using multiple advanced techniques to accurately ascertain levels of contamination as well as to determine their exact surface density. Detailed fabrication methods as well as characterization techniques have been discussed.

Thin Film Approaches to the SRF Cavity Problem Fabrication and Characterization of Superconducting Thin Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beringer, Douglas

Superconducting Radio Frequency (SRF) cavities are responsible for the acceleration of charged particles to relativistic velocities in most modern linear accelerators, such as those employed at high-energy research facilities like Thomas Jefferson National Laboratory’s CEBAF and the LHC at CERN. Recognizing SRF as primarily a surface phenomenon enables the possibility of applying thin films to the interior surface of SRF cavities, opening a formidable tool chest of opportunities by combining and designing materials that offer greater performance benefit. Thus, while improvements in radio frequency cavity design and refinements in cavity processing techniques have improved accelerator performance and efficiency – 1.5more » GHz bulk niobium SRF cavities have achieved accelerating gradients in excess of 35 MV/m – there exist fundamental material bounds in bulk superconductors limiting the maximally sustained accelerating field gradient (≈ 45 MV/m for Nb) where inevitable thermodynamic breakdown occurs. With state of the art Nb based cavity design fast approaching these theoretical limits, novel material innovations must be sought in order to realize next generation SRF cavities. One proposed method to improve SRF performance is to utilize thin film superconducting-insulating-superconducting (SIS) multilayer structures to effectively magnetically screen a bulk superconducting layer such that it can operate at higher field gradients before suffering critically detrimental SRF losses. This dissertation focuses on the production and characterization of thin film superconductors for such SIS layers for radio frequency applications. Correlated studies on structure, surface morphology and superconducting properties of epitaxial Nb and MgB2 thin films are presented.« less

Epitaxial Bi2 FeCrO6 Multiferroic Thin Film as a New Visible Light Absorbing Photocathode Material.

PubMed

Li, Shun; AlOtaibi, Bandar; Huang, Wei; Mi, Zetian; Serpone, Nick; Nechache, Riad; Rosei, Federico

2015-08-26

Ferroelectric materials have been studied increasingly for solar energy conversion technologies due to the efficient charge separation driven by the polarization induced internal electric field. However, their insufficient conversion efficiency is still a major challenge. Here, a photocathode material of epitaxial double perovskite Bi(2) FeCrO(6) multiferroic thin film is reported with a suitable conduction band position and small bandgap (1.9-2.1 eV), for visible-light-driven reduction of water to hydrogen. Photoelectrochemical measurements show that the highest photocurrent density up to -1.02 mA cm(-2) at a potential of -0.97 V versus reversible hydrogen electrode is obtained in p-type Bi(2) FeCrO(6) thin film photocathode grown on SrTiO(3) substrate under AM 1.5G simulated sunlight. In addition, a twofold enhancement of photocurrent density is obtained after negatively poling the Bi(2) FeCrO(6) thin film, as a result of modulation of the band structure by suitable control of the internal electric field gradient originating from the ferroelectric polarization in the Bi(2) FeCrO(6) films. The findings validate the use of multiferroic Bi(2) FeCrO(6) thin films as photocathode materials, and also prove that the manipulation of internal fields through polarization in ferroelectric materials is a promising strategy for the design of improved photoelectrodes and smart devices for solar energy conversion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atmospheric-Pressure-Spray, Chemical- Vapor-Deposited Thin-Film Materials Being Developed for High Power-to- Weight-Ratio Space Photovoltaic Applications

NASA Technical Reports Server (NTRS)

Hepp, Aloysius F.; Harris, Jerry D.; Raffaelle, Ryne P.; Banger, Kulbinder K.; Smith, Mark A.; Cowen, Jonathan E.

2001-01-01

The key to achieving high specific power (watts per kilogram) space photovoltaic arrays is the development of high-efficiency thin-film solar cells that are fabricated on lightweight, space-qualified substrates such as Kapton (DuPont) or another polymer film. Cell efficiencies of 20 percent air mass zero (AM0) are required. One of the major obstacles to developing lightweight, flexible, thin-film solar cells is the unavailability of lightweight substrate or superstrate materials that are compatible with current deposition techniques. There are two solutions for working around this problem: (1) develop new substrate or superstrate materials that are compatible with current deposition techniques, or (2) develop new deposition techniques that are compatible with existing materials. The NASA Glenn Research Center has been focusing on the latter approach and has been developing a deposition technique for depositing thin-film absorbers at temperatures below 400 C.

Dynamics in thin folded polymer films

NASA Astrophysics Data System (ADS)

Croll, Andrew; Rozairo, Damith

Origami and Kirigami inspired structures depend on a complex interplay between geometry and material properties. While clearly important to the overall function, very little attention has focused on how extreme curvatures and singularities in real materials influence the overall dynamic behaviour of folded structures. In this work we use a set of three polymer thin films in order to closely examine the interaction of material and geometry. Specifically, we use polydimethylsiloxane (PDMS), polystyrene (PS) and polycarbonate (PC) thin films which we subject to loading in several model geometries of varying complexity. Depending on the material, vastly different responses are noted in our experiments; D-cones can annihilate, cut or lead to a crumpling cascade when pushed through a film. Remarkably, order can be generated with additional perturbation. Finally, the role of adhesion in complex folded structures can be addressed. AFOSR under the Young Investigator Program (FA9550-15-1-0168).

Eco-Friendly and Biodegradable Biopolymer Chitosan/Y₂O₃ Composite Materials in Flexible Organic Thin-Film Transistors.

PubMed

Du, Bo-Wei; Hu, Shao-Ying; Singh, Ranjodh; Tsai, Tsung-Tso; Lin, Ching-Chang; Ko, Fu-Hsiang

2017-09-03

The waste from semiconductor manufacturing processes causes serious pollution to the environment. In this work, a non-toxic material was developed under room temperature conditions for the fabrication of green electronics. Flexible organic thin-film transistors (OTFTs) on plastic substrates are increasingly in demand due to their high visible transmission and small size for use as displays and wearable devices. This work investigates and analyzes the structured formation of aqueous solutions of the non-toxic and biodegradable biopolymer, chitosan, blended with high-k-value, non-toxic, and biocompatible Y₂O₃ nanoparticles. Chitosan thin films blended with Y₂O₃ nanoparticles were adopted as the gate dielectric thin film in OTFTs, and an improvement in the dielectric properties and pinholes was observed. Meanwhile, the on/off current ratio was increased by 100 times, and a low leakage current was observed. In general, the blended chitosan/Y₂O₃ thin films used as the gate dielectric of OTFTs are non-toxic, environmentally friendly, and operate at low voltages. These OTFTs can be used on surfaces with different curvature radii because of their flexibility.

Transparent flexible thermoelectric material based on non-toxic earth-abundant p-type copper iodide thin film

PubMed Central

Yang, C.; Souchay, D.; Kneiß, M.; Bogner, M.; Wei, H. M.; Lorenz, M.; Oeckler, O.; Benstetter, G.; Fu, Y. Q.; Grundmann, M.

2017-01-01

Thermoelectric devices that are flexible and optically transparent hold unique promise for future electronics. However, development of invisible thermoelectric elements is hindered by the lack of p-type transparent thermoelectric materials. Here we present the superior room-temperature thermoelectric performance of p-type transparent copper iodide (CuI) thin films. Large Seebeck coefficients and power factors of the obtained CuI thin films are analysed based on a single-band model. The low-thermal conductivity of the CuI films is attributed to a combined effect of the heavy element iodine and strong phonon scattering. Accordingly, we achieve a large thermoelectric figure of merit of ZT=0.21 at 300 K for the CuI films, which is three orders of magnitude higher compared with state-of-the-art p-type transparent materials. A transparent and flexible CuI-based thermoelectric element is demonstrated. Our findings open a path for multifunctional technologies combing transparent electronics, flexible electronics and thermoelectricity. PMID:28681842

Transparent flexible thermoelectric material based on non-toxic earth-abundant p-type copper iodide thin film.

PubMed

Yang, C; Souchay, D; Kneiß, M; Bogner, M; Wei, H M; Lorenz, M; Oeckler, O; Benstetter, G; Fu, Y Q; Grundmann, M

2017-07-06

Thermoelectric devices that are flexible and optically transparent hold unique promise for future electronics. However, development of invisible thermoelectric elements is hindered by the lack of p-type transparent thermoelectric materials. Here we present the superior room-temperature thermoelectric performance of p-type transparent copper iodide (CuI) thin films. Large Seebeck coefficients and power factors of the obtained CuI thin films are analysed based on a single-band model. The low-thermal conductivity of the CuI films is attributed to a combined effect of the heavy element iodine and strong phonon scattering. Accordingly, we achieve a large thermoelectric figure of merit of ZT=0.21 at 300 K for the CuI films, which is three orders of magnitude higher compared with state-of-the-art p-type transparent materials. A transparent and flexible CuI-based thermoelectric element is demonstrated. Our findings open a path for multifunctional technologies combing transparent electronics, flexible electronics and thermoelectricity.

a Brief Survey on Basic Properties of Thin Films for Device Application

NASA Astrophysics Data System (ADS)

Rao, M. C.; Shekhawat, M. S.

Thin film materials are the key elements of continued technological advances made in the fields of optoelectronic, photonic and magnetic devices. Thin film studies have directly or indirectly advanced many new areas of research in solid state physics and chemistry which are based on phenomena uniquely characteristic of the thickness, geometry and structure of the film. The processing of materials into thin films allows easy integration into various types of devices. Thin films are extremely thermally stable and reasonably hard, but they are fragile. On the other hand organic materials have reasonable thermal stability and are tough, but are soft. Thin film mechanical properties can be measured by tensile testing of freestanding films and by the micro beam cantilever deflection technique, but the easiest way is by means of nanoindentation. Optical experiments provide a good way of examining the properties of semiconductors. Particularly measuring the absorption coefficient for various energies gives information about the band gaps of the material. Thin film materials have been used in semiconductor devices, wireless communications, telecommunications, integrated circuits, rectifiers, transistors, solar cells, light-emitting diodes, photoconductors and light crystal displays, lithography, micro- electromechanical systems (MEMS) and multifunctional emerging coatings, as well as other emerging cutting technologies.

Growth and characterization of β-Ga2O3 thin films by molecular beam epitaxy for deep-UV photodetectors

NASA Astrophysics Data System (ADS)

Ghose, Susmita; Rahman, Shafiqur; Hong, Liang; Rojas-Ramirez, Juan Salvador; Jin, Hanbyul; Park, Kibog; Klie, Robert; Droopad, Ravi

2017-09-01

The growth of high quality epitaxial beta-gallium oxide (β-Ga2O3) using a compound source by molecular beam epitaxy has been demonstrated on c-plane sapphire (Al2O3) substrates. The compound source provides oxidized gallium molecules in addition to oxygen when heated from an iridium crucible in a high temperature effusion cell enabling a lower heat of formation for the growth of Ga2O3, resulting in a more efficient growth process. This source also enabled the growth of crystalline β-Ga2O3 without the need for additional oxygen. The influence of the substrate temperatures on the crystal structure and quality, chemical bonding, surface morphology, and optical properties has been systematically evaluated by x-ray diffraction, scanning transmission electron microscopy, x-ray photoelectron spectroscopy, atomic force microscopy, spectroscopic ellipsometry, and UV-vis spectroscopy. Under optimized growth conditions, all films exhibited pure (" separators="|2 ¯01 ) oriented β-Ga2O3 thin films with six-fold rotational symmetry when grown on a sapphire substrate. The thin films demonstrated significant absorption in the deep-ultraviolet (UV) region with an optical bandgap around 5.0 eV and a refractive index of 1.9. A deep-UV photodetector fabricated on the high quality β-Ga2O3 thin film exhibits high resistance and small dark current (4.25 nA) with expected photoresponse for 254 nm UV light irradiation suggesting that the material grown using the compound source is a potential candidate for deep-ultraviolet photodetectors.

Structural comparison of Ag-Ge-S bulk glasses and thin films

NASA Astrophysics Data System (ADS)

Wang, Fei; Jain, Mukul; Dunn, Porter; de Leo, Carter; Boolchand, Punit

2007-03-01

Ternary glasses of composition (GeS3)1-xAgx (x=0.1 and 0.2) are studied in form of bulk and thin films. Bulk glasses are synthesized and examined in Raman scattering and SEM. Raman scattering results of bulk glasses show that with increasing x, an increasing fraction of the Ag additive enters the base glass as Ag^+ with S^-anions serving to form thiogermanate species with one, two and three non-bridging S^- species. SEM measurements of the bulk glass show the material is intrinsically phase separated. White colored islands are observed distributed in a dark base. The EDS measurements show islands are Ag rich and the base is relatively Ag deficient. The Ag rich islands are expected to be mainly glassy phase Ag2S. Thin films of same compositions are fabricated using thermal evaporation. Films are evaporated following two different procedures to prevent the material from spitting. One method was preheating outgas and the other method was using tungsten mesh wrapped boats. The stoichiometry and molecular structure of films under each procedure are analyzed by Raman scattering and SEM to be compared with bulk glasses.

Photocurrent spectroscopy of pentacene thin film transistors

NASA Astrophysics Data System (ADS)

Breban, Mihaela

We demonstrate the application of photocurrent modulation spectroscopy in characterizing the performance of organic thin-film transistors. A parallel analysis of the direct current and photocurrent voltage characteristics provides a model free determination of the field-effect mobility and the density of free carriers in the transistor channel as a function of the applied gate voltage. Applying this technique to pentacene thin-film transistors demonstrates that the mobility increases as V1/3g . The free-carrier density is approximately 1/10 of the expected capacitive charge, and the mobility increases monotonically with the free carrier density, consistent with the trap and release model of transport. Also, the modulated photocurrent spectroscopy can be used as a probe of defect states in pentacene thin film transistors, measuring simultaneously the magnitude and the phase of the photocurrent as a function of the modulation frequency. This is accomplished by modeling the photo-carrier generation process as exciton dissociation via interaction with localized traps. Experimental data reveal a Gaussian distribution of localized states centered around 0.3 eV above the highest occupied molecular orbital. We also investigated the effect of the gate dielectric material with our probe and found that the position of the extracted Gaussian slightly shifts, consistent with the expected image charge effect for Pn through the dielectric substrate. Also shifts in the Gaussian position for samples fabricated with variable deposition conditions are correlated with changes in Pn morphology. The morphological differences between Pn films were also detected in current-voltage characteristics and photocurrent spectra. However, the origin of the ubiquitous 0.3 eV defect in Pn seems to be unrelated to structural differences in Pn films.

Long-Wave Infrared (LWIR) Molecular Laser-Induced Breakdown Spectroscopy (LIBS) Emissions of Thin Solid Explosive Powder Films Deposited on Aluminum Substrates.

PubMed

Yang, Clayton S-C; Jin, Feng; Trivedi, Sudhir B; Brown, Ei E; Hommerich, Uwe; Tripathi, Ashish; Samuels, Alan C

2017-04-01

Thin solid films made of high nitro (NO 2 )/nitrate (NO 3 ) content explosives were deposited on sand-blasted aluminum substrates and then studied using a mercury-cadmium-telluride (MCT) linear array detection system that is capable of rapidly capturing a broad spectrum of atomic and molecular laser-induced breakdown spectroscopy (LIBS) emissions in the long-wave infrared region (LWIR; ∼5.6-10 µm). Despite the similarities of their chemical compositions and structures, thin films of three commonly used explosives (RDX, HMX, and PETN) studied in this work can be rapidly identified in the ambient air by their molecular LIBS emission signatures in the LWIR region. A preliminary assessment of the detection limit for a thin film of RDX on aluminum appears to be much lower than 60 µg/cm 2 . This LWIR LIBS setup is capable of rapidly probing and charactering samples without the need for elaborate sample preparation and also offers the possibility of a simultaneous ultraviolet visible and LWIR LIBS measurement.

Preparation methodologies and nano/microstructural evaluation of metal/semiconductor thin films.

PubMed

Chen, Zhiwen; Jiao, Zheng; Wu, Minghong; Shek, Chan-Hung; Wu, C M Lawrence; Lai, Joseph K L

2012-01-01

Metal/semiconductor thin films are a class of unique materials that are widespread technological applications, particularly in the field of microelectronic devices. Assessment strategies of fractal and tures are of fundamental importance in the development of nano/microdevices. This review presents the preparation methodologies and nano/microstructural evaluation of metal/semiconductor thin films including Au/Ge bilayer films and Pd-Ge alloy thin films, which show in the form of fractals and nanocrystals. Firstly, the extended version of Au/Ge thin films for the fractal crystallization of amorphous Ge and the formation of nanocrystals developed with improved micro- and nanostructured features are described in Section 2. Secondly, the nano/microstructural characteristics of Pd/Ge alloy thin films during annealing have been investigated in detail and described in Section 3. Finally, we will draw the conclusions from the present work as shown in Section 4. It is expected that the preparation methodologies developed and the knowledge of nano/microstructural evolution gained in metal/semiconductor thin films, including Au/Ge bilayer films and Pd-Ge alloy thin films, will provide an important fundamental basis underpinning further interdisciplinary research in these fields such as physics, chemistry, materials science, and nanoscience and nanotechnology, leading to promising exciting opportunities for future technological applications involving these thin films.

Black thin film silicon

NASA Astrophysics Data System (ADS)

Koynov, Svetoslav; Brandt, Martin S.; Stutzmann, Martin

2011-08-01

"Black etching" has been proposed previously as a method for the nanoscale texturing of silicon surfaces, which results in an almost complete suppression of reflectivity in the spectral range of absorption relevant for photovoltaics. The method modifies the topmost 150 to 300 nm of the material and thus also is applicable for thin films of silicon. The present work is focused on the optical effects induced by the black-etching treatment on hydrogenated amorphous and microcrystalline silicon thin films, in particular with respect to their application in solar cells. In addition to a strong reduction of the reflectivity, efficient light trapping within the modified thin films is found. The enhancement of the optical absorption due to the light trapping is investigated via photometric measurements and photothermal deflection spectroscopy. The correlation of the texture morphology (characterized via atomic force microscopy) with the optical effects is discussed in terms of an effective medium with gradually varying optical density and in the framework of the theory of statistical light trapping. Photoconductivity spectra directly show that the light trapping causes a significant prolongation of the light path within the black silicon films by up to 15 μm for ˜1 μm thick films, leading to a significant increase of the absorption in the red.

Atomic-scale visualization of oxide thin-film surfaces.

PubMed

Iwaya, Katsuya; Ohsawa, Takeo; Shimizu, Ryota; Okada, Yoshinori; Hitosugi, Taro

2018-01-01

The interfaces of complex oxide heterostructures exhibit intriguing phenomena not observed in their constituent materials. The oxide thin-film growth of such heterostructures has been successfully controlled with unit-cell precision; however, atomic-scale understandings of oxide thin-film surfaces and interfaces have remained insufficient. We examined, with atomic precision, the surface and electronic structures of oxide thin films and their growth processes using low-temperature scanning tunneling microscopy. Our results reveal that oxide thin-film surface structures are complicated in contrast to the general perception and that atomically ordered surfaces can be achieved with careful attention to the surface preparation. Such atomically ordered oxide thin-film surfaces offer great opportunities not only for investigating the microscopic origins of interfacial phenomena but also for exploring new surface phenomena and for studying the electronic states of complex oxides that are inaccessible using bulk samples.

Metal Induced Growth of Si Thin Films and NiSi Nanowires

DTIC Science & Technology

2010-02-25

Zinc Oxide Over MIG Silicon- We have been studying the formation of ZnO films by RF sputtering. Part of this study deals with...about 50 nm. 15. SUBJECT TERMS Thin film silicon, solar cells, thin film transistors , nanowires, metal induced growth 16. SECURITY CLASSIFICATION...to achieve, µc-Si is more desirable than a-Si due to its increased mobility. Thin film µc-Si is also a popular material for thin film transistors

Thin film photovoltaic device and process of manufacture

DOEpatents

Albright, S.P.; Chamberlin, R.

1997-10-07

Provided is a thin film photovoltaic device and a method of manufacturing the device. The thin film photovoltaic device comprises a film layer having particles which are smaller than about 30 microns in size held in an electrically insulating matrix material to reduce the potential for electrical shorting through the film layer. The film layer may be provided by depositing preformed particles onto a surrogate substrate and binding the particles in a film-forming matrix material to form a flexible sheet with the film layer. The flexible sheet may be separated from the surrogate substrate and cut into flexible strips. A plurality of the flexible strips may be located adjacent to and supported by a common supporting substrate to form a photovoltaic module having a plurality of electrically interconnected photovoltaic cells. 13 figs.

Thin film photovoltaic device and process of manufacture

DOEpatents

Albright, Scot P.; Chamberlin, Rhodes

1999-02-09

Provided is a thin film photovoltaic device and a method of manufacturing the device. The thin film photovoltaic device comprises a film layer having particles which are smaller than about 30 microns in size held in an electrically insulating matrix material to reduce the potential for electrical shorting through the film layer. The film layer may be provided by depositing preformed particles onto a surrogate substrate and binding the particles in a film-forming matrix material to form a flexible sheet with the film layer. The flexible sheet may be separated from the surrogate substrate and cut into flexible strips. A plurality of the flexible strips may be located adjacent to and supported by a common supporting substrate to form a photovoltaic module having a plurality of electrically interconnected photovoltaic cells.

Thin film photovoltaic device and process of manufacture

DOEpatents

Albright, S.P.; Chamberlin, R.

1999-02-09

Provided is a thin film photovoltaic device and a method of manufacturing the device. The thin film photovoltaic device comprises a film layer having particles which are smaller than about 30 microns in size held in an electrically insulating matrix material to reduce the potential for electrical shorting through the film layer. The film layer may be provided by depositing preformed particles onto a surrogate substrate and binding the particles in a film-forming matrix material to form a flexible sheet with the film layer. The flexible sheet may be separated from the surrogate substrate and cut into flexible strips. A plurality of the flexible strips may be located adjacent to and supported by a common supporting substrate to form a photovoltaic module having a plurality of electrically interconnected photovoltaic cells. 13 figs.

Thin film photovoltaic device and process of manufacture

DOEpatents

Albright, Scot P.; Chamberlin, Rhodes

1997-10-07

Provided is a thin film photovoltaic device and a method of manufacturing the device. The thin film photovoltaic device comprises a film layer having particles which are smaller than about 30 microns in size held in an electrically insulating matrix material to reduce the potential for electrical shorting through the film layer. The film layer may be provided by depositing preformed particles onto a surrogate substrate and binding the particles in a film-forming matrix material to form a flexible sheet with the film layer. The flexible sheet may be separated from the surrogate substrate and cut into flexible strips. A plurality of the flexible strips may be located adjacent to and supported by a common supporting substrate to form a photovoltaic module having a plurality of electrically interconnected photovoltaic cells.

Altering properties of cerium oxide thin films by Rh doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ševčíková, Klára, E-mail: klarak.sevcikova@seznam.cz; NIMS Beamline Station at SPring-8, National Institute for Materials Science, Sayo, Hyogo 679-5148; Nehasil, Václav, E-mail: nehasil@mbox.troja.mff.cuni.cz

2015-07-15

Highlights: • Thin films of ceria doped by rhodium deposited by RF magnetron sputtering. • Concentration of rhodium has great impact on properties of Rh–CeO{sub x} thin films. • Intensive oxygen migration in films with low concentration of rhodium. • Oxygen migration suppressed in films with high amount of Rh dopants. - Abstract: Ceria containing highly dispersed ions of rhodium is a promising material for catalytic applications. The Rh–CeO{sub x} thin films with different concentrations of rhodium were deposited by RF magnetron sputtering and were studied by soft and hard X-ray photoelectron spectroscopies, Temperature programmed reaction and X-ray powder diffractionmore » techniques. The sputtered films consist of rhodium–cerium mixed oxide where cerium exhibits a mixed valency of Ce{sup 4+} and Ce{sup 3+} and rhodium occurs in two oxidation states, Rh{sup 3+} and Rh{sup n+}. We show that the concentration of rhodium has a great influence on the chemical composition, structure and reducibility of the Rh–CeO{sub x} thin films. The films with low concentrations of rhodium are polycrystalline, while the films with higher amount of Rh dopants are amorphous. The morphology of the films strongly influences the mobility of oxygen in the material. Therefore, varying the concentration of rhodium in Rh–CeO{sub x} thin films leads to preparing materials with different properties.« less

Study on Buckling of Stiff Thin Films on Soft Substrates as Functional Materials

NASA Astrophysics Data System (ADS)

Ma, Teng

In engineering, buckling is mechanical instability of walls or columns under compression and usually is a problem that engineers try to prevent. In everyday life buckles (wrinkles) on different substrates are ubiquitous -- from human skin to a rotten apple they are a commonly observed phenomenon. It seems that buckles with macroscopic wavelengths are not technologically useful; over the past decade or so, however, thanks to the widespread availability of soft polymers and silicone materials micro-buckles with wavelengths in submicron to micron scale have received increasing attention because it is useful for generating well-ordered periodic microstructures spontaneously without conventional lithographic techniques. This thesis investigates the buckling behavior of thin stiff films on soft polymeric substrates and explores a variety of applications, ranging from optical gratings, optical masks, energy harvest to energy storage. A laser scanning technique is proposed to detect micro-strain induced by thermomechanical loads and a periodic buckling microstructure is employed as a diffraction grating with broad wavelength tunability, which is spontaneously generated from a metallic thin film on polymer substrates. A mechanical strategy is also presented for quantitatively buckling nanoribbons of piezoelectric material on polymer substrates involving the combined use of lithographically patterning surface adhesion sites and transfer printing technique. The precisely engineered buckling configurations provide a route to energy harvesters with extremely high levels of stretchability. This stiff-thin-film/polymer hybrid structure is further employed into electrochemical field to circumvent the electrochemically-driven stress issue in silicon-anode-based lithium ion batteries. It shows that the initial flat silicon-nanoribbon-anode on a polymer substrate tends to buckle to mitigate the lithiation-induced stress so as to avoid the pulverization of silicon anode. Spontaneously

Paper-Thin Plastic Film Soaks Up Sun to Create Solar Energy

NASA Technical Reports Server (NTRS)

2006-01-01

A non-crystallized silicon known as amorphous silicon is the semiconductor material most frequently chosen for deposition, because it is a strong absorber of light. According to the U.S. Department of Energy, amorphous silicon absorbs solar radiation 40 times more efficiently than single-crystal silicon, and a thin film only about 1-micrometer (one one-millionth of a meter) thick containing amorphous silicon can absorb 90 percent of the usable light energy shining on it. Peak efficiency and significant reduction in the use of semiconductor and thin film materials translate directly into time and money savings for manufacturers. Thanks in part to NASA, thin film solar cells derived from amorphous silicon are gaining more and more attention in a market that has otherwise been dominated by mono- and poly-crystalline silicon cells for years. At Glenn Research Center, the Photovoltaic & Space Environments Branch conducts research focused on developing this type of thin film solar cell for space applications. Placing solar cells on thin film materials provides NASA with an attractively priced solution to fabricating other types of solar cells, given that thin film solar cells require significantly less semiconductor material to generate power. Using the super-lightweight solar materials also affords NASA the opportunity to cut down on payload weight during vehicle launches, as well as the weight of spacecraft being sent into orbit.

Recognition of Conformational Changes in β-Lactoglobulin by Molecularly Imprinted Thin Films

PubMed Central

Turner, Nicholas W.; Liu, Xiao; Piletsky, Sergey A.; Hlady, Vladimir; Britt, David W.

2008-01-01

Pathogenesis in protein conformational diseases is initiated by changes in protein secondary structure. This molecular restructuring presents an opportunity for novel shape-based detection approaches, as protein molecular weight and chemistry are otherwise unaltered. Here we apply molecular imprinting to discriminate between distinct conformations of the model protein β-lactoglobulin (BLG). Thermal- and fluoro-alcohol-induced BLG isoforms were imprinted in thin films of 3-aminophenylboronic acid on quartz crystal microbalance chips. Enhanced rebinding of the template isoform was observed in all cases when compared to the binding of nontemplate isoforms over the concentration range of 1–100 µg mL−1. Furthermore, it was observed that the greater the changes in the secondary structure of the template protein the lower the binding of native BLG challenges to the imprint, suggesting a strong steric influence in the recognition system. This feasibility study is a first demonstration of molecular imprints for recognition of distinct conformations of the same protein. PMID:17665947

Recognition of conformational changes in beta-lactoglobulin by molecularly imprinted thin films.

PubMed

Turner, Nicholas W; Liu, Xiao; Piletsky, Sergey A; Hlady, Vladimir; Britt, David W

2007-09-01

Pathogenesis in protein conformational diseases is initiated by changes in protein secondary structure. This molecular restructuring presents an opportunity for novel shape-based detection approaches, as protein molecular weight and chemistry are otherwise unaltered. Here we apply molecular imprinting to discriminate between distinct conformations of the model protein beta-lactoglobulin (BLG). Thermal- and fluoro-alcohol-induced BLG isoforms were imprinted in thin films of 3-aminophenylboronic acid on quartz crystal microbalance chips. Enhanced rebinding of the template isoform was observed in all cases when compared to the binding of nontemplate isoforms over the concentration range of 1-100 microg mL(-1). Furthermore, it was observed that the greater the changes in the secondary structure of the template protein the lower the binding of native BLG challenges to the imprint, suggesting a strong steric influence in the recognition system. This feasibility study is a first demonstration of molecular imprints for recognition of distinct conformations of the same protein.

Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers

NASA Astrophysics Data System (ADS)

Best, James P.; Michler, Johann; Liu, Jianxi; Wang, Zhengbang; Tsotsalas, Manuel; Maeder, Xavier; Röse, Silvana; Oberst, Vanessa; Liu, Jinxuan; Walheim, Stefan; Gliemann, Hartmut; Weidler, Peter G.; Redel, Engelbert; Wöll, Christof

2015-09-01

Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth method. Control over respective fabrication processes allowed for tuning of the thickness of the thin film systems with a high degree of precision. It was found that the mechanical indentation of such thin films is significantly affected by the substrate properties; however, elastic parameters were able to be decoupled for constituent thin-film materials (EITO ≈ 96.7 GPa, EHKUST-1 ≈ 22.0 GPa). For indentation of multilayer stacks, it was found that as the layer thicknesses were increased, while holding the relative thickness of ITO and HKUST-1 constant, the resistance to deformation was significantly altered. Such an observation is likely due to small, albeit significant, changes in film texture, interfacial roughness, size effects, and controlling deformation mechanism as a result of increasing material deposition during processing. Such effects may have consequences regarding the rational mechanical design and utilization of MOF-based hybrid thin-film devices.

Novel organic semiconductors and dielectric materials for high performance and low-voltage organic thin-film transistors

NASA Astrophysics Data System (ADS)

Yoon, Myung-Han

Two novel classes of organic semiconductors based on perfluoroarene/arene-modified oligothiophenes and perfluoroacyl/acyl-derivatized quaterthiophens are developed. The frontier molecular orbital energies of these compounds are studied by optical spectroscopy and electrochemistry while solid-state/film properties are investigated by thermal analysis, x-ray diffraction, and scanning electron microscopy. Organic thin film transistors (OTFTs) performance parameters are discussed in terms of the interplay between semiconductor molecular energetics and film morphologies/microstructures. For perfluoroarene-thiophene oligomer systems, majority charge carrier type and mobility exhibit a strong correlation with the regiochemistry of perfluoroarene incorporation. In quaterthiophene-based semiconductors, carbonyl-functionalization allows tuning of the majority carrier type from p-type to ambipolar and to n-type. In situ conversion of a p-type semiconducting film to n-type film is also demonstrated. Very thin self-assembled or spin-on organic dielectric films have been integrated into OTFTs to achieve 1 - 2 V operating voltages. These new dielectrics are deposited either by layer-by-layer solution phase deposition of molecular precursors or by spin-coating a mixture of polymer and crosslinker, resulting in smooth and virtually pinhole-free thin films having exceptionally large capacitances (300--700 nF/cm2) and low leakage currents (10 -9 - 10-7 A/cm2). These organic dielectrics are compatible with various vapor- or solution-deposited p- and n-channel organic semiconductors. Furthermore, it is demonstrated that spin-on crosslinked-polymer-blend dielectrics can be employed for large-area/patterned electronics, and complementary inverters. A general approach for probing semiconductor-dielectric interface effects on OTFT performance parameters using bilayer gate dielectrics is presented. Organic semiconductors having p-, n-type, or ambipolar majority charge carriers are grown on

Energy Migration in Organic Thin Films--From Excitons to Polarons

NASA Astrophysics Data System (ADS)

Mullenbach, Tyler K.

The rise of organic photovoltaic devices (OPVs) and organic light-emitting devices has generated interest in the physics governing exciton and polaron dynamics in thin films. Energy transfer has been well studied in dilute solutions, but there are emergent properties in thin films and greater complications due to complex morphologies which must be better understood. Despite the intense interest in energy transport in thin films, experimental limitations have slowed discoveries. Here, a new perspective of OPV operation is presented where photovoltage, instead of photocurrent, plays the fundamental role. By exploiting this new vantage point the first method of measuring the diffusion length (LD) of dark (non-luminescent) excitons is developed, a novel photodetector is invented, and the ability to watch exciton arrival, in real-time, at the donor-acceptor heterojunction is presented. Using an enhanced understanding of exciton migration in thin films, paradigms for enhancing LD by molecular modifications are discovered, and the first exciton gate is experimentally and theoretically demonstrated. Generation of polarons from exciton dissociation represents a second phase of energy migration in OPVs that remains understudied. Current approaches are capable of measuring the rate of charge carrier recombination only at open-circuit. To enable a better understanding of polaron dynamics in thin films, two new approaches are presented which are capable of measuring both the charge carrier recombination and transit rates at any OPV operating voltage. These techniques pave the way for a more complete understanding of charge carrier kinetics in molecular thin films.

Thin polymeric films for building biohybrid microrobots.

PubMed

Ricotti, Leonardo; Fujie, Toshinori

2017-03-06

This paper aims to describe the disruptive potential that polymeric thin films have in the field of biohybrid devices and to review the recent efforts in this area. Thin (thickness  <  1 mm) and ultra-thin (thickness  <  1 µm) matrices possess a series of intriguing features, such as large surface area/volume ratio, high flexibility, chemical and physical surface tailorability, etc. This enables the fabrication of advanced bio/non-bio interfaces able to efficiently drive cell-material interactions, which are the key for optimizing biohybrid device performances. Thin films can thus represent suitable platforms on which living and artificial elements are coupled, with the aim of exploiting the unique features of living cells/tissues. This may allow to carry out certain tasks, not achievable with fully artificial technologies. In the paper, after a description of the desirable chemical/physical cues to be targeted and of the fabrication, functionalization and characterization procedures to be used for thin and ultra-thin films, the state-of-the-art of biohybrid microrobots based on micro/nano-membranes are described and discussed. The research efforts in this field are rather recent and they focus on: (1) self-beating cells (such as cardiomyocytes) able to induce a relatively large deformation of the underlying substrates, but affected by a limited controllability by external users; (2) skeletal muscle cells, more difficult to engineer in mature and functional contractile tissues, but featured by a higher controllability. In this context, the different materials used and the performances achieved are analyzed. Despite recent interesting advancements and signs of maturity of this research field, important scientific and technological steps are still needed. In the paper some possible future perspectives are described, mainly concerning thin film manipulation and assembly in multilayer 3D systems, new advanced materials to be used for the fabrication

Piezoelectric thin films and their applications for electronics

NASA Astrophysics Data System (ADS)

Yoshino, Yukio

2009-03-01

ZnO and AlN piezoelectric thin films have been studied for applications in bulk acoustic wave (BAW) resonator. This article introduces methods of forming ZnO and AlN piezoelectric thin films by radio frequency sputtering and applications of BAW resonators considering the relationship between the crystallinity of piezoelectric thin films and the characteristics of the BAW resonators. Using ZnO thin films, BAW resonators were fabricated for a contour mode at 3.58 MHz and thickness modes from 200 MHz to 5 GHz. The ZnO thin films were combined with various materials, substrates, and thin films to minimize the temperature coefficient of frequency (TCF). The minimum TCF of BAW resonators was approximately 2 ppm/°C in the range -20 to 80 °C. The electromechanical coupling coefficient (k2) in a 1.9 GHz BAW resonator was 6.9%. Using AlN thin films, 5-20 GHz BAW resonators with an ultrathin membrane were realized. The membrane thickness of a 20 GHz BAW resonator was about 200 nm, k2 was 6.1%, and the quality factor (Q) was about 280. Q decreased with increasing resonant frequency. The value of k2 is almost the same for 5-20 GHz resonators. This result could be obtained by improving the thickness uniformity, by controlling internal stress of thin films, and by controlling the crystallinity of AlN piezoelectric thin film.

TI--CR--AL--O thin film resistors

DOEpatents

Jankowski, Alan F.; Schmid, Anthony P.

2000-01-01

Thin films of Ti--Cr--Al--O are used as a resistor material. The films are rf sputter deposited from ceramic targets using a reactive working gas mixture of Ar and O.sub.2. Resistivity values from 10.sup.4 to 10.sup.10 Ohm-cm have been measured for Ti--Cr--Al--O film <1 .mu.m thick. The film resistivity can be discretely selected through control of the target composition and the deposition parameters. The application of Ti--Cr--Al--O as a thin film resistor has been found to be thermodynamically stable, unlike other metal-oxide films. The Ti--Cr--Al--O film can be used as a vertical or lateral resistor, for example, as a layer beneath a field emission cathode in a flat panel display; or used to control surface emissivity, for example, as a coating on an insulating material such as vertical wall supports in flat panel displays.

Magnon dispersion in thin magnetic films.

PubMed

Balashov, T; Buczek, P; Sandratskii, L; Ernst, A; Wulfhekel, W

2014-10-01

Although the dispersion of magnons has been measured in many bulk materials, few studies deal with the changes in the dispersion when the material is in the form of a thin film, a system that is of interest for applications. Here we review inelastic tunneling spectroscopy studies of magnon dispersion in Mn/Cu3Au(1 0 0) and present new studies on Co and Ni thin films on Cu(1 0 0). The dispersion in Mn and Co films closely follows the dispersion of bulk samples with negligible dependence on thickness. The lifetime of magnons depends slightly on film thickness, and decreases considerably as the magnon energy increases. In Ni/Cu(1 0 0) films the thickness dependence of dispersion is much more pronounced. The measurements indicate a considerable mode softening for thinner films. Magnon lifetimes decrease dramatically near the edge of the Brillouin zone due to a close proximity of the Stoner continuum. The experimental study is supported by first-principles calculations.

Laser Deposition of Polymer Nanocomposite Thin Films and Hard Materials and Their Optical Characterization

DTIC Science & Technology

2013-12-05

visible light on instruments such as microscope tips and micro- surgical tools. Hard carbon known as diamond-like carbon films produced by pulsed laser ...visible (610 nm) LED source and a supplemental infra-red 980-nm laser diode (for the studies of the upconversion fluorescence). The basic package...5/2013 Final Performance Report 15 Sep 2012- 14 Sep 2013 LASER DEPOSITION OF POLYMER NANOCOMPOSITE THIN FILMS AND HARD MATERIALS AND THEIR OPTICAL

Surface induced molecular dynamics of thin lipid films confined to submicron cavities: A 1H multiple-quantum NMR study

NASA Astrophysics Data System (ADS)

Jagadeesh, B.; Prabhakar, A.; Demco, D. E.; Buda, A.; Blümich, B.

2005-03-01

The dynamics and molecular order of thin lipid (lecithin) films confined to 200, 100 and 20 nm cylindrical pores with varying surface coverage, were investigated by 1H multiple-quantum NMR. The results show that the molecular dynamics in the surface controlled layers are less hindered compared to those in the bulk. Dynamic heterogeneity among terminal CH 3 groups is evident. Enhanced dynamic freedom is observed for films with area per molecule, ˜ 128 Å 2. The results are discussed in terms of changes in the lipid molecular organization with respect to surface concentration, its plausible motional modes and dynamic heterogeneity.

Giant surfactants of poly(ethylene oxide)- b-polystyrene-(molecular nanoparticle): nanoparticle-driven self-assembly with sub-10-nm nanostructures in thin films

NASA Astrophysics Data System (ADS)

Hsu, Chih-Hao; Lin, Zhiwei; Dong, Xue-Hui; Hsieh, I.-Fan; Cheng, Stephen Z. D.

2014-03-01

Giant surfactants are built upon precisely attaching shape- and volume-persistent molecular nanoparticles (MNP) to polymeric flexible tails. The unique class of self-assembling materials, giant surfactants, has been demonstrated to form self-assembled ordered nanostructures, and their self-assembly behaviors are remarkably sensitive to primary chemical structures. In this work, two sets of giant surfactants with functionalized MNP attached to diblock copolymer tails were studied in thin films. Carboxylic acid-functionalized [60]fullerene (AC60) tethered with PEO- b-PS (PEO-PS-AC60) represents an ABA' (hydrophilic-hydrophobic-hydrophilic) giant surfactant, and fluoro-functionalized polyhedral oligomeric silsesquioxane (FPOSS) tethered with PEO- b-PS (PEO-PS-FPOSS) represents an ABC (hydrophilic-hydrophobic-omniphobic) one. The dissimilar chemical natures of the MNPs result in different arrangement of MNPs in self-assembled structures, the dispersion of AC60 in PEO domain and the single domain of FPOSS. Moreover, the chemically bonded MNPs could induce the originally disordered small molecular PEO- b-PS to form ordered cylindrical and lamellar structure, as evidenced by TEM and GISAXS, leading to sub-10-nm nanostructures of copolymer in the thin film state.

Thin Film Ceramic Strain Sensor Development for Harsh Environments: Interim Report on Identification of Candidate Thin Film Ceramics to Test for Viability for Static Strain Sensor Development

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Hunter, Gary W.

2006-01-01

The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in propulsion system applications. In order to have a more passive method of negating changes of resistance due to temperature, an effort is underway at NASA Glenn to develop high temperature thin film ceramic static strain gauges for application in turbine engines, specifically in the fan and compressor modules on blades. Other applications can be on aircraft hot section structures and on thermal protection systems. The near-term interim goal of the research effort was to identify candidate thin film ceramic sensor materials to test for viability and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. This goal was achieved by a thorough literature search for ceramics that have the potential for application as high temperature thin film strain gauges, reviewing potential candidate materials for chemical and physical compatibility with our microfabrication procedures and substrates.

Flexible Thin Metal Film Thermal Sensing System

NASA Technical Reports Server (NTRS)

Thomsen, Donald Laurence (Inventor)

2012-01-01

A flexible thin metal film thermal sensing system is provided. A thermally-conductive film made from a thermally-insulating material is doped with thermally-conductive material. At least one layer of electrically-conductive metal is deposited directly onto a surface of the thermally-conductive film. One or more devices are coupled to the layer(s) to measure an electrical characteristic associated therewith as an indication of temperature.

Germanium Lift-Off Masks for Thin Metal Film Patterning

NASA Technical Reports Server (NTRS)

Brown, Ari

2012-01-01

A technique has been developed for patterning thin metallic films that are, in turn, used to fabricate microelectronics circuitry and thin-film sensors. The technique uses germanium thin films as lift-off masks. This requires development of a technique to strip or undercut the germanium chemically without affecting the deposited metal. Unlike in the case of conventional polymeric lift-off masks, the substrate can be exposed to very high temperatures during processing (sputter deposition). The reason why polymeric liftoff masks cannot be exposed to very high temperatures (greater than 100 C) is because (a) they can become cross linked, making lift-off very difficult if not impossible, and (b) they can outgas nitrogen and oxygen, which then can react with the metal being deposited. Consequently, this innovation is expected to find use in the fabrication of transition edge sensors and microwave kinetic inductance detectors, which use thin superconducting films deposited at high temperature as their sensing elements. Transition edge sensors, microwave kinetic inductance detectors, and their circuitry are comprised of superconducting thin films, for example Nb and TiN. Reactive ion etching can be used to pattern these films; however, reactive ion etching also damages the underlying substrate, which is unwanted in many instances. Polymeric lift-off techniques permit thin-film patterning without any substrate damage, but they are difficult to remove and the polymer can outgas during thin-film deposition. The outgassed material can then react with the film with the consequence of altered and non-reproducible materials properties, which, in turn, is deleterious for sensors and their circuitry. The purpose of this innovation was to fabricate a germanium lift-off mask to be used for patterning thin metal films.

Nanoporous poly(3-hexylthiophene) thin film structures from self-organization of a tunable molecular bottlebrush scaffold

DOE PAGES

Ahn, Suk-kyun; Carrillo, Jan-Michael Y.; Keum, Jong K.; ...

2017-04-07

The ability to widely tune the design of macromolecular bottlebrushes provides access to self-assembled nanostructures formed by microphase segregation in melt, thin film and solution that depart from structures adopted by simple linear copolymers. A series of random bottlebrush copolymers containing poly(3-hexylthiophene) (P3HT) and poly(D,L-lactide) (PLA) side chains grafted on a poly(norbornene) backbone were synthesized via ring-opening metathesis polymerization (ROMP) using the grafting through approach. P3HT side chains induce a physical aggregation of the bottlebrush copolymers upon solvent removal by vacuum drying, primarily driven by attractive π–π interactions; however, the amount of aggregation can be controlled by adjusting side chainmore » composition or by adding linear P3HT chains to the bottlebrush copolymers. Coarse-grained molecular dynamics simulations reveal that linear P3HT chains preferentially associate with P3HT side chains of bottlebrush copolymers, which tends to reduce the aggregation. The nanoscale morphology of microphase segregated thin films created by casting P3HT–PLA random bottlebrush copolymers is highly dependent on the composition of P3HT and PLA side chains, while domain spacing of nanostructures is mainly determined by the length of the side chains. The selective removal of PLA side chains under alkaline conditions generates nanoporous P3HT structures that can be tuned by manipulating molecular design of the bottlebrush scaffold, which is affected by molecular weight and grafting density of the side chains, and their sequence. Furthermore, the ability to exploit the unusual architecture of bottlebrushes to fabricate tunable nanoporous P3HT thin film structures may be a useful way to design templates for optoelectronic applications or membranes for separations.« less

Nanoporous poly(3-hexylthiophene) thin film structures from self-organization of a tunable molecular bottlebrush scaffold

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahn, Suk-kyun; Carrillo, Jan-Michael Y.; Keum, Jong K.

The ability to widely tune the design of macromolecular bottlebrushes provides access to self-assembled nanostructures formed by microphase segregation in melt, thin film and solution that depart from structures adopted by simple linear copolymers. A series of random bottlebrush copolymers containing poly(3-hexylthiophene) (P3HT) and poly(D,L-lactide) (PLA) side chains grafted on a poly(norbornene) backbone were synthesized via ring-opening metathesis polymerization (ROMP) using the grafting through approach. P3HT side chains induce a physical aggregation of the bottlebrush copolymers upon solvent removal by vacuum drying, primarily driven by attractive π–π interactions; however, the amount of aggregation can be controlled by adjusting side chainmore » composition or by adding linear P3HT chains to the bottlebrush copolymers. Coarse-grained molecular dynamics simulations reveal that linear P3HT chains preferentially associate with P3HT side chains of bottlebrush copolymers, which tends to reduce the aggregation. The nanoscale morphology of microphase segregated thin films created by casting P3HT–PLA random bottlebrush copolymers is highly dependent on the composition of P3HT and PLA side chains, while domain spacing of nanostructures is mainly determined by the length of the side chains. The selective removal of PLA side chains under alkaline conditions generates nanoporous P3HT structures that can be tuned by manipulating molecular design of the bottlebrush scaffold, which is affected by molecular weight and grafting density of the side chains, and their sequence. Furthermore, the ability to exploit the unusual architecture of bottlebrushes to fabricate tunable nanoporous P3HT thin film structures may be a useful way to design templates for optoelectronic applications or membranes for separations.« less

Spectroscopic Ellipsometry Studies of Ag and ZnO Thin Films and Their Interfaces for Thin Film Photovoltaics

NASA Astrophysics Data System (ADS)

Sainju, Deepak

Many modern optical and electronic devices, including photovoltaic devices, consist of multilayered thin film structures. Spectroscopic ellipsometry (SE) is a critically important characterization technique for such multilayers. SE can be applied to measure key parameters related to the structural, optical, and electrical properties of the components of multilayers with high accuracy and precision. One of the key advantages of this non-destructive technique is its capability of monitoring the growth dynamics of thin films in-situ and in real time with monolayer level precision. In this dissertation, the techniques of SE have been applied to study the component layer materials and structures used as back-reflectors and as the transparent contact layers in thin film photovoltaic technologies, including hydrogenated silicon (Si:H), copper indium-gallium diselenide (CIGS), and cadmium telluride (CdTe). The component layer materials, including silver and both intrinsic and doped zinc oxide, are fabricated on crystalline silicon and glass substrates using magnetron sputtering techniques. These thin films are measured in-situ and in real time as well as ex-situ by spectroscopic ellipsometry in order to extract parameters related to the structural properties, such as bulk layer thickness and surface roughness layer thickness and their time evolution, the latter information specific to real time measurements. The index of refraction and extinction coefficient or complex dielectric function of a single unknown layer can also be obtained from the measurement versus photon energy. Applying analytical expressions for these optical properties versus photon energy, parameters that describe electronic transport, such as electrical resistivity and electron scattering time, can be extracted. The SE technique is also performed as the sample is heated in order to derive the effects of annealing on the optical properties and derived electrical transport parameters, as well as the

In-situ ellipsometry: applications to thin film research, development, and production

NASA Astrophysics Data System (ADS)

Kief, M. T.

1999-07-01

Many industries including the optics industry, semiconductor industry, and magnetic storage industry are deeply rooted in the science and technology of thin film materials and thin film based devices. Research in novel thin film systems and the engineering of artificial structures increasingly requires a control on the atomic scale in both thickness and lateral order. Development of the deposition and fabrication processes for these thin film structures requires technical sophistication and efficiency combined with an understanding of the multi-faceted process interactions. The production of these materials necessitates a remarkable degree of control to minimize scrap and assure good performance. Furthermore, in today's industry these operations must occur at an ever accelerating pace. In this article, we will review one technique which can make these challenges more tractable - insitu ellipsometry. This is a very powerful tool which is capable of characterizing thin film processes in real-time. We review the art and illustrate with novel applications to metal thin film growth. In addition, we will illustrate how information obtained with insitu ellipsometry can predict the end use thin film properties such as the transport properties. In conclusion, further advances in insitu ellipsometry and its applications will be discussed in terms of needs and trends as a tool for thin film research, development and production.

Advanced thin film thermocouples

NASA Technical Reports Server (NTRS)

Kreider, K. G.; Semancik, S.; Olson, C.

1984-01-01

The fabrication, materials characterization, and performance of thin film platinum rhodium thermocouples on gas turbine alloys was investigated. The materials chosen for the study were the turbine blade alloy systems MAR M200+Hf with NiCoCrAlY and FeCrAlY coatings, and vane alloy systems MAR M509 with FeCrAlY. Research was focussed on making improvements in the problem areas of coating substrate stability, adhesion, and insulation reliability and durability. Diffusion profiles between the substrate and coating with and without barrier coatings of Al2O3 are reported. The relationships between fabrication parameters of thermal oxidation and sputtering of the insulator and its characterization and performance are described. The best thin film thermocouples were fabricated with the NiCoCrAlY coatings which were thermally oxidized and sputter coated with Al2O3.

Synthesis and characterization of nanostructured bismuth selenide thin films.

PubMed

Sun, Zhengliang; Liufu, Shengcong; Chen, Lidong

2010-12-07

Nanostructured bismuth selenide thin films have been successfully fabricated on a silicon substrate at low temperature by rational design of the precursor solution. Bi(2)Se(3) thin films were constructed of coalesced lamella in the thickness of 50-80 nm. The nucleation and growth process of Bi(2)Se(3) thin films, as well as the influence of solution chemistry on the film structure were investigated in detail. As one of the most promising thermoelectric materials, the thermoelectric properties of the prepared Bi(2)Se(3) thin films were also investigated. The power factor increased with increasing carrier mobility, coming from the enlarged crystallites and enhanced coalesced structure, and reached 1 μW cm(-1) K(-1).

Reduced temperature-dependent thermal conductivity of magnetite thin films by controlling film thickness

PubMed Central

2014-01-01

We report on the out-of-plane thermal conductivities of epitaxial Fe3O4 thin films with thicknesses of 100, 300, and 400 nm, prepared using pulsed laser deposition (PLD) on SiO2/Si substrates. The four-point probe three-omega (3-ω) method was used for thermal conductivity measurements of the Fe3O4 thin films in the temperature range of 20 to 300 K. By measuring the temperature-dependent thermal characteristics of the Fe3O4 thin films, we realized that their thermal conductivities significantly decreased with decreasing grain size and thickness of the films. The out-of-plane thermal conductivities of the Fe3O4 films were found to be in the range of 0.52 to 3.51 W/m · K at 300 K. For 100-nm film, we found that the thermal conductivity was as low as approximately 0.52 W/m · K, which was 1.7 to 11.5 order of magnitude lower than the thermal conductivity of bulk material at 300 K. Furthermore, we calculated the temperature dependence of the thermal conductivity of these Fe3O4 films using a simple theoretical Callaway model for comparison with the experimental data. We found that the Callaway model predictions agree reasonably with the experimental data. We then noticed that the thin film-based oxide materials could be efficient thermoelectric materials to achieve high performance in thermoelectric devices. PMID:24571956

Solar Selective Coatings Prepared From Thin-Film Molecular Mixtures and Evaluated

NASA Technical Reports Server (NTRS)

Jaworske, Don A.

2003-01-01

Thin films composed of molecular mixtures of metal and dielectric are being considered for use as solar selective coatings for a variety of space power applications. By controlling molecular mixing during ion-beam sputter deposition, researchers can tailor the solar selective coatings to have the combined properties of high solar absorptance and low infrared emittance. On orbit, these combined properties simultaneously maximize the amount of solar energy captured by the coating and minimize the amount of thermal energy radiated. The solar selective coatings are envisioned for use on minisatellites, for applications where solar energy is used to power heat engines or to heat remote regions in the interior of the spacecraft. Such systems may be useful for various missions, particularly those to middle Earth orbit. Sunlight must be concentrated by a factor of 100 or more to achieve the desired heat inlet operating temperature. At lower concentration factors, the temperature of the heat inlet surface of the heat engine is too low for efficient operation, and at high concentration factors, cavity type heat receivers become attractive. The an artist's concept of a heat engine, with the annular heat absorbing surface near the focus of the concentrator coated with a solar selective coating is shown. In this artist's concept, the heat absorbing surface powers a small Stirling convertor. The astronaut's gloved hand is provided for scale. Several thin-film molecular mixtures have been prepared and evaluated to date, including mixtures of aluminum and aluminum oxide, nickel and aluminum oxide, titanium and aluminum oxide, and platinum and aluminum oxide. For example, a 2400- Angstrom thick mixture of titanium and aluminum oxide was found to have a solar absorptance of 0.93 and an infrared emittance of 0.06. On the basis of tests performed under flowing nitrogen at temperatures as high as 680 C, the coating appeared to be durable at elevated temperatures. Additional durability

All-Ceramic Thin Film Battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

BOYLE, TIMOTHY J.; INGERSOLL, DAVID; CYGAN, RANDALL T.

2002-11-01

We have undertaken the synthesis of a thin film ''All Ceramic Battery'' (ACB) using solution route processes. Based on the literature and experimental results, we selected SnO{sub 2}, LiCoO{sub 2}, and LiLaTiO{sub 3} (LLT) as the anode, cathode, and electrolyte, respectively. Strain induced by lattice mismatch between the cathode and bottom electrode, as estimated by computational calculations, indicate that thin film orientations for batteries when thicknesses are as low as 500 {angstrom} are strongly controlled by surface energies. Therefore, we chose platinized silicon as the basal platform based on our previous experience with this material. The anode thin films weremore » generated by standard spin-cast methods and processing using a solution of [Sn(ONep)]{sub 8} and HOAc which was found to form Sn{sub 6}(O){sub 4}(ONep){sub 4}. Electrochemical evaluation showed that the SnO{sub 2} was converted to Sn{sup o} during the first cycle. The cathode was also prepared by spin coating using the novel [Li(ONep)]{sub 8} and Co(OAc){sub 2}. The films could be electrochemically cycled (i.e., charged/discharged), with all of the associated structural changes being observable by XRD. Computational models indicated that the LLT electrolyte would be the best available ceramic material for use as the electrolyte. The LLT was synthesized from [Li(ONep)]{sub 8}, [Ti(ONep){sub 4}]{sub 2}, and La(DIP){sub 3}(py){sub 3} with RTP processing at 900 C being necessary to form the perovskite phase. Alternatively, a novel route to thin films of the block co-polymer ORMOLYTE was developed. The integration of these components was undertaken with each part of the assembly being identifiably by XRD analysis (this will allow us to follow the progress of the charge/discharge cycles of the battery during use). SEM investigations revealed the films were continuous with minimal mixing. All initial testing of the thin-film cathode/electrolyte/anode ACB devices revealed electrical shorting

Thin Film Sensors for Surface Measurements

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Wrbanek, John D.; Fralick, Gustave C.

2001-01-01

Advanced thin film sensors that can provide accurate surface temperature, strain, and heat flux measurements have been developed at NASA Glenn Research Center. These sensors provide minimally intrusive characterization of advanced propulsion materials and components in hostile, high-temperature environments as well as validation of propulsion system design codes. The sensors are designed for applications on different material systems and engine components for testing in engine simulation facilities. Thin film thermocouples and strain gauges for the measurement of surface temperature and strain have been demonstrated on metals, ceramics and advanced ceramic-based composites of various component configurations. Test environments have included both air-breathing and space propulsion-based engine and burner rig environments at surface temperatures up to 1100 C and under high gas flow and pressure conditions. The technologies developed for these sensors as well as for a thin film heat flux gauge have been integrated into a single multifunctional gauge for the simultaneous real-time measurement of surface temperature, strain, and heat flux. This is the first step toward the development of smart sensors with integrated signal conditioning and high temperature electronics that would have the capability to provide feedback to the operating system in real-time. A description of the fabrication process for the thin film sensors and multifunctional gauge will be provided. In addition, the material systems on which the sensors have been demonstrated, the test facilities and the results of the tests to-date will be described. Finally, the results will be provided of the current effort to demonstrate the capabilities of the multifunctional gauge.

Method of improving field emission characteristics of diamond thin films

DOEpatents

Krauss, A.R.; Gruen, D.M.

1999-05-11

A method of preparing diamond thin films with improved field emission properties is disclosed. The method includes preparing a diamond thin film on a substrate, such as Mo, W, Si and Ni. An atmosphere of hydrogen (molecular or atomic) can be provided above the already deposited film to form absorbed hydrogen to reduce the work function and enhance field emission properties of the diamond film. In addition, hydrogen can be absorbed on intergranular surfaces to enhance electrical conductivity of the diamond film. The treated diamond film can be part of a microtip array in a flat panel display. 3 figs.

Method of improving field emission characteristics of diamond thin films

DOEpatents

Krauss, Alan R.; Gruen, Dieter M.

1999-01-01

A method of preparing diamond thin films with improved field emission properties. The method includes preparing a diamond thin film on a substrate, such as Mo, W, Si and Ni. An atmosphere of hydrogen (molecular or atomic) can be provided above the already deposited film to form absorbed hydrogen to reduce the work function and enhance field emission properties of the diamond film. In addition, hydrogen can be absorbed on intergranular surfaces to enhance electrical conductivity of the diamond film. The treated diamond film can be part of a microtip array in a flat panel display.

Nonlinear optical thin films

NASA Technical Reports Server (NTRS)

Leslie, Thomas M.

1993-01-01

A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film

Optical and structural properties of cobalt-permalloy slanted columnar heterostructure thin films

NASA Astrophysics Data System (ADS)

Sekora, Derek; Briley, Chad; Schubert, Mathias; Schubert, Eva

2017-11-01

Optical and structural properties of sequential Co-column-NiFe-column slanted columnar heterostructure thin films with an Al2O3 passivation coating are reported. Electron-beam evaporated glancing angle deposition is utilized to deposit the sequential multiple-material slanted columnar heterostructure thin films. Mueller matrix generalized spectroscopic ellipsometry data is analyzed with a best-match model approach employing the anisotropic Bruggeman effective medium approximation formalism to determine bulk-like and anisotropic optical and structural properties of the individual Co and NiFe slanted columnar material sub-layers. Scanning electron microscopy is applied to image the Co-NiFe sequential growth properties and to verify the results of the ellipsometric analysis. Comparisons to single-material slanted columnar thin films and optically bulk solid thin films are presented and discussed. We find that the optical and structural properties of each material sub-layer of the sequential slanted columnar heterostructure film are distinct from each other and resemble those of their respective single-material counterparts.

A simple solution to the problem of effective utilisation of the target material for pulsed laser deposition of thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuzanyan, A S; Kuzanyan, A A; Petrosyan, V A

The factors determining the efficiency of the target material utilisation for pulsed laser deposition of films are considered. The target volume is calculated, which is evaporated in the ablation process by the focused laser radiation having a rectangular form. The new device is suggested and developed for obtaining thin films by the method of laser deposition, which is specific in the employment of a simple optical system mounted outside a deposition chamber that comprises two lenses and the diaphragm and focuses the laser beam onto a target in the form of a sector-like spot. Thin films of CuO and YBaCuOmore » were deposited with this device. Several deposition cycles revealed that the target material is consumed uniformly from the entire surface of the target. A maximal spread of the target thickness was not greater than ±2% both prior to deposition and after it. The device designed provides a high coefficient of the target material utilisation efficiency. (laser deposition of thin films)« less

Recent progress in high-mobility thin-film transistors based on multilayer 2D materials

NASA Astrophysics Data System (ADS)

Hong, Young Ki; Liu, Na; Yin, Demin; Hong, Seongin; Kim, Dong Hak; Kim, Sunkook; Choi, Woong; Yoon, Youngki

2017-04-01

Two-dimensional (2D) layered semiconductors are emerging as promising candidates for next-generation thin-film electronics because of their high mobility, relatively large bandgap, low-power switching, and the availability of large-area growth methods. Thin-film transistors (TFTs) based on multilayer transition metal dichalcogenides or black phosphorus offer unique opportunities for next-generation electronic and optoelectronic devices. Here, we review recent progress in high-mobility transistors based on multilayer 2D semiconductors. We describe the theoretical background on characterizing methods of TFT performance and material properties, followed by their applications in flexible, transparent, and optoelectronic devices. Finally, we highlight some of the methods used in metal-semiconductor contacts, hybrid structures, heterostructures, and chemical doping to improve device performance.

Effect of native oxide layers on copper thin-film tensile properties: A reactive molecular dynamics study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skarlinski, Michael D., E-mail: michael.skarlinski@rochester.edu; Quesnel, David J.; Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627

2015-12-21

Metal-oxide layers are likely to be present on metallic nano-structures due to either environmental exposure during use, or high temperature processing techniques such as annealing. It is well known that nano-structured metals have vastly different mechanical properties from bulk metals; however, difficulties in modeling the transition between metallic and ionic bonding have prevented the computational investigation of the effects of oxide surface layers. Newly developed charge-optimized many body [Liang et al., Mater. Sci. Eng., R 74, 255 (2013)] potentials are used to perform fully reactive molecular dynamics simulations which elucidate the effects that metal-oxide layers have on the mechanical propertiesmore » of a copper thin-film. Simulated tensile tests are performed on thin-films while using different strain-rates, temperatures, and oxide thicknesses to evaluate changes in yield stress, modulus, and failure mechanisms. Findings indicate that copper-thin film mechanical properties are strongly affected by native oxide layers. The formed oxide layers have an amorphous structure with lower Cu-O bond-densities than bulk CuO, and a mixture of Cu{sub 2}O and CuO charge character. It is found that oxidation will cause modifications to the strain response of the elastic modulii, producing a stiffened modulii at low temperatures (<75 K) and low strain values (<5%), and a softened modulii at higher temperatures. While under strain, structural reorganization within the oxide layers facilitates brittle yielding through nucleation of defects across the oxide/metal interface. The oxide-free copper thin-film yielding mechanism is found to be a tensile-axis reorientation and grain creation. The oxide layers change the observed yielding mechanism, allowing for the inner copper thin-film to sustain an FCC-to-BCC transition during yielding. The mechanical properties are fit to a thermodynamic model based on classical nucleation theory. The fit implies that the oxidation of

Characterization of sputtered iridium oxide thin films on planar and laser micro-structured platinum thin film surfaces for neural stimulation applications

NASA Astrophysics Data System (ADS)

Thanawala, Sachin

Electrical stimulation of neurons provides promising results for treatment of a number of diseases and for restoration of lost function. Clinical examples include retinal stimulation for treatment of blindness and cochlear implants for deafness and deep brain stimulation for treatment of Parkinsons disease. A wide variety of materials have been tested for fabrication of electrodes for neural stimulation applications, some of which are platinum and its alloys, titanium nitride, and iridium oxide. In this study iridium oxide thin films were sputtered onto laser micro-structured platinum thin films by pulsed-DC reactive sputtering of iridium metal in oxygen-containing atmosphere, to obtain high charge capacity coatings for neural stimulation applications. The micro-structuring of platinum films was achieved by a pulsed-laser-based technique (KrF excimer laser emitting at lambda=248nm). The surface morphology of the micro-structured films was studied using different surface characterization techniques. In-vitro biocompatibility of these laser micro-structured films coated with iridium oxide thin films was evaluated using cortical neurons isolated from rat embryo brain. Characterization of these laser micro-structured films coated with iridium oxide, by cyclic voltammetry and impedance spectroscopy has revealed a considerable decrease in impedance and increase in charge capacity. A comparison between amorphous and crystalline iridium oxide thin films as electrode materials indicated that amorphous iridium oxide has significantly higher charge capacity and lower impedance making it preferable material for neural stimulation application. Our biocompatibility studies show that neural cells can grow and differentiate successfully on our laser micro-structured films coated with iridium oxide. This indicates that reactively sputtered iridium oxide (SIROF) is biocompatible.

Pyrolyzed thin film carbon

NASA Technical Reports Server (NTRS)

Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor); Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor)

2010-01-01

A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

Magnetically engineered smart thin films: toward lab-on-chip ultra-sensitive molecular imaging.

PubMed

Hassan, Muhammad A; Saqib, Mudassara; Shaikh, Haseeb; Ahmad, Nasir M; Elaissari, Abdelhamid

2013-03-01

Magnetically responsive engineered smart thin films of nanoferrites as contrast agent are employed to develop surface based magnetic resonance imaging to acquire simple yet fast molecular imaging. The work presented here can be of significant potential for future lab-on-chip point-of-care diagnostics from the whole blood pool on almost any substrates to reduce or even prevent clinical studies involve a living organism to enhance the non-invasive imaging to advance the '3Rs' of work in animals-replacement, refinement and reduction.

Thin Film Approaches to the SRF Cavity Problem: Fabrication and Characterization of Superconducting Thin Films

NASA Astrophysics Data System (ADS)

Beringer, Douglas B.

Superconducting Radio Frequency (SRF) cavities are responsible for the acceleration of charged particles to relativistic velocities in most modern linear accelerators, such as those employed at high-energy research facilities like Thomas Jefferson National Laboratory's CEBAF and the LHC at CERN. Recognizing SRF as primarily a surface phenomenon enables the possibility of applying thin films to the interior surface of SRF cavities, opening a formidable tool chest of opportunities by combining and designing materials that offer greater benefit. Thus, while improvements in radio frequency cavity design and refinements in cavity processing techniques have improved accelerator performance and efficiency - 1.5 GHz bulk niobium SRF cavities have achieved accelerating gradients in excess of 35 MV/m - there exist fundamental material bounds in bulk superconductors limiting the maximally sustained accelerating field gradient (approximately 45 MV/m for Niobium) where inevitable thermodynamic breakdown occurs. With state of the art niobium based cavity design fast approaching these theoretical limits, novel material innovations must be sought in order to realize next generation SRF cavities. One proposed method to improve SRF performance is to utilize thin film superconducting-insulating-superconducting (SIS) multilayer structures to effectively magnetically screen a bulk superconducting layer such that it can operate at higher field gradients before suffering critically detrimental SRF losses. This dissertation focuses on the production and characterization of thin film superconductors for such SIS layers for radio-frequency applications.

Methods for producing thin film charge selective transport layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammond, Scott Ryan; Olson, Dana C.; van Hest, Marinus Franciscus Antonius Maria

Methods for producing thin film charge selective transport layers are provided. In one embodiment, a method for forming a thin film charge selective transport layer comprises: providing a precursor solution comprising a metal containing reactive precursor material dissolved into a complexing solvent; depositing the precursor solution onto a surface of a substrate to form a film; and forming a charge selective transport layer on the substrate by annealing the film.

Nanomechanical investigation of thin-film electroceramic/metal-organic framework multilayers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Best, James P., E-mail: james.best@empa.ch, E-mail: engelbert.redel@kit.edu, E-mail: christof.woell@kit.edu; Michler, Johann; Maeder, Xavier

2015-09-07

Thin-film multilayer stacks of mechanically hard magnetron sputtered indium tin oxide (ITO) and mechanically soft highly porous surface anchored metal-organic framework (SURMOF) HKUST-1 were studied using nanoindentation. Crystalline, continuous, and monolithic surface anchored MOF thin films were fabricated using a liquid-phase epitaxial growth method. Control over respective fabrication processes allowed for tuning of the thickness of the thin film systems with a high degree of precision. It was found that the mechanical indentation of such thin films is significantly affected by the substrate properties; however, elastic parameters were able to be decoupled for constituent thin-film materials (E{sub ITO} ≈ 96.7 GPa, E{sub HKUST−1} ≈ 22.0 GPa).more » For indentation of multilayer stacks, it was found that as the layer thicknesses were increased, while holding the relative thickness of ITO and HKUST-1 constant, the resistance to deformation was significantly altered. Such an observation is likely due to small, albeit significant, changes in film texture, interfacial roughness, size effects, and controlling deformation mechanism as a result of increasing material deposition during processing. Such effects may have consequences regarding the rational mechanical design and utilization of MOF-based hybrid thin-film devices.« less

Suppression of copper thin film loss during graphene synthesis.

PubMed

Lee, Alvin L; Tao, Li; Akinwande, Deji

2015-01-28

Thin metal films can be used to catalyze the growth of nanomaterials in place of the bulk metal, while greatly reducing the amount of material used. A big drawback of copper thin films (0.5-1.5 μm thick) is that, under high temperature/vacuum synthesis, the mass loss of films severely reduces the process time due to discontinuities in the metal film, thereby limiting the time scale for controlling metal grain and film growth. In this work, we have developed a facile method, namely "covered growth" to extend the time copper thin films can be exposed to high temperature/vacuum environment for graphene synthesis. The key to preventing severe mass loss of copper film during the high temperature chemical vapor deposition (CVD) process is to have a cover piece on top of the growth substrate. This new "covered growth" method enables the high-temperature annealing of the copper film upward of 4 h with minimal mass loss, while increasing copper film grain and graphene domain size. Graphene was then successfully grown on the capped copper film with subsequent transfer for device fabrication. Device characterization indicated equivalent physical, chemical, and electrical properties to conventional CVD graphene. Our "covered growth" provides a convenient and effective solution to the mass loss issue of thin films that serve as catalysts for a variety of 2D material syntheses.

Mechanical properties of thin-film materials evaluated from amplitude-dependent internal friction

NASA Astrophysics Data System (ADS)

Nishino, Yoichi

1999-09-01

A method is presented to evaluate the mechanical properties of thin-film materials from measurements of the amplitude-dependent internal friction. According to the constitutive equation, the internal friction in the film can be determined separately from measured damping of the film/substrate composite. The internal friction in aluminum films is dependent on the strain amplitude that is approximately two orders of magnitude higher than that for bulk aluminum. On the basis of the microplasticity theory, the amplitude-dependent internal friction in the film can be converted into the plastic strain as a function of effective stress on dislocation motion. The mechanical responses thus obtained for aluminum films show that the plastic strain of the order of 10-9 increases nonlinearly with increasing stress. These curves tend to shift to a higher stress with decreasing film thickness and also with decreasing temperature, both indicating a suppression of microplastic flow. The microflow stress at a constant level of the plastic strain varies inversely with the film thickness, provided the grain size is larger than the film thickness. The film thickness effect in the microplastic range can be well explained by the bowing of a dislocation segment whose ends are pinned at the film surface and at the film/substrate interface.

In-situ ellipsometry: applications to thin film research, development, and production

NASA Astrophysics Data System (ADS)

Kief, Mark T.

1999-07-01

Many industries including the optics industry, semiconductor industry, and magnetic storage industry are deeply rooted in the science and technology of the film materials and thin film based devices. Research in novel thin film systems and the engineering of artificial structures increasingly requires a control on the atomic scale in both thickness and lateral order. Development of the deposition and fabrication processes for these thin film structures requires technical sophistication and efficiency combined with an understanding of the multi-faceted process interactions. The production of these materials necessitates a remarkable degree of control to minimize scrap and assure good performance. Furthermore, in today's industry these operations must occur at an ever accelerating pace. In this article, we will review one technique which can make these challenges more tractable-- insitu ellipsometry. This is a very powerful tool which is capable of characterizing thin film processes in real-time. We review the art and illustrate with novel applications to metal thin film growth. In addition, we will illustrate how information obtained with insitu ellipsometry can predict the end use thin film properties such as the transport properties. In conclusion, further advances in insitu ellipsometry and its applications will be discussed in terms of needs and trends as a tool for thin film research, development and production.

Sol-gel preparation of silica and titania thin films

NASA Astrophysics Data System (ADS)

Thoř, Tomáš; Václavík, Jan

2016-11-01

Thin films of silicon dioxide (SiO2) and titanium dioxide (TiO2) for application in precision optics prepared via the solgel route are being investigated in this paper. The sol-gel process presents a low cost approach, which is capable of tailoring thin films of various materials in optical grade quality. Both SiO2 and TiO2 are materials well known for their application in the field of anti-reflective and also highly reflective optical coatings. For precision optics purposes, thickness control and high quality of such coatings are of utmost importance. In this work, thin films were deposited on microscope glass slides substrates using the dip-coating technique from a solution based on alkoxide precursors of tetraethyl orthosilicate (TEOS) and titanium isopropoxide (TIP) for SiO2 and TiO2, respectively. As-deposited films were studied using spectroscopic ellipsometry to determine their thickness and refractive index. Using a semi-empirical equation, a relationship between the coating speed and the heat-treated film thickness was described for both SiO2 and TiO2 thin films. This allows us to control the final heat-treated thin film thickness by simply adjusting the coating speed. Furthermore, films' surface was studied using the white-light interferometry. As-prepared films exhibited low surface roughness with the area roughness parameter Sq being on average of 0.799 nm and 0.33 nm for SiO2 and TiO2, respectively.

Phases, line tension and pattern formation in molecularly thin films at the air-water interface

NASA Astrophysics Data System (ADS)

Mandal, Pritam

A Langmuir film, which is a molecularly thin insoluble film on a liquid substrate, is one practical realization of a quasi-two dimensional matter. The major advantages of this system for the study of phase separation and phase co-existence are (a) it allows accurate control of the components and molecular area of the film and (b) it can be studied by various methods that require very flat films. Phase separation in molecularly thin films plays an important role in a range of systems from biomembranes to biosensors. For example, phase-separated lipid nano-domains in biomembranes are thought to play crucial roles in membrane function. I use Brewster Angel Microscopy (BAM) coupled with Fluorescence Microscopy (FM) and static Light Scattering Microscopy (LSM) to image phases and patterns within Langmuir films. The three microscopic techniques --- BAM, FM and LSM --- are complimentary to each other, providing distinct sets of information. They allow direct comparison with literature results in lipid systems. I have quantitatively validated the use of detailed hydrodynamic simulations to determine line tension in monolayers. Line tension decreases as temperature rises. This decrease gives us information on the entropy associated with the line, and thus about line structure. I carefully consider the thermodynamics of line energy and entropy to make this connection. In the longer run, LSM will be exploited to give us further information about line structure. I have also extended the technique by testing it on domains within the curved surface of a bilayer vesicle. I also note that in the same way that the presence of surface-active agents, known as surfactants, affects surface energy, the addiction of line active agents alters the inter-phase line energy. Thus my results set to stage to systematically study the influence of line active agents ---'linactants' --- on the inter-phase line energy. Hierarchal self-assembled chiral patterns were observed as a function of

Preparation of LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries by a mist CVD process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tadanaga, Kiyoharu, E-mail: tadanaga@chem.osakafu-u.ac.jp; Yamaguchi, Akihiro; Sakuda, Atsushi

2014-05-01

Highlights: • LiMn{sub 2}O{sub 4} thin films were prepared by using the mist CVD process. • An aqueous solution of lithium and manganese acetates is used for the precursor solution. • The cell with the LiMn{sub 2}O{sub 4} thin films exhibited a capacity of about 80 mAh/g. • The cell showed good cycling performance during 10 cycles. - Abstract: LiMn{sub 2}O{sub 4} cathode thin films for thin film lithium secondary batteries were prepared by using so-called the “mist CVD process”, employing an aqueous solution of lithium acetate and manganese acetate, as the source of Li and Mn, respectively. The aqueousmore » solution of starting materials was ultrasonically atomized to form mist particles, and mists were transferred by nitrogen gas to silica glass substrate to form thin films. FE-SEM observation revealed that thin films obtained by this process were dense and smooth, and thin films with a thickness of about 750 nm were obtained. The electrochemical cell with the thin films obtained by sintering at 700 °C exhibited a capacity of about 80 mAh/g, and the cell showed good cycling performance during 10 cycles.« less

Multiferroic RMnO3 thin films

NASA Astrophysics Data System (ADS)

Fontcuberta, Josep

2015-03-01

Multiferroic materials have received an astonishing attention in the last decades due to expectations that potential coupling between distinct ferroic orders could inspire new applications and new device concepts. As a result, a new knowledge on coupling mechanisms and materials science has dramatically emerged. Multiferroic RMnO3 perovskites are central to this progress, providing a suitable platform to tailor spin-spin and spin-lattice interactions. With views towards applications, the development of thin films of multiferroic materials have also progressed enormously and nowadays thin-film manganites are available, with properties mimicking those of bulk compounds. Here we review achievements on the growth of hexagonal and orthorhombic RMnO3 epitaxial thin films and the characterization of their magnetic and ferroelectric properties, we discuss some challenging issues, and we suggest some guidelines for future research and developments. En ce qui concerne les applications, le développement de films minces de matériaux multiferroïques a aussi énormément progressé, et de nos jours des films minces de manganites avec des propriétés similaires à celles des matériaux massifs existent. Nous passons en revue ici les résultats obtenus dans le domaine de la croissance de couches minces épitaxiés de RMnO3 hexagonal et orthorhombique et de la caractérisation de leurs propriétés magnétiques et ferroélectriques. Nous discutons certains enjeux et proposons quelques idées pour des recherches et développements futurs.

Advances in Thin Film Thermocouple Durability Under High Temperature and Pressure Testing Conditions

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Fralick, Gustave C.; Taylor, Keith F.

1999-01-01

Thin film thermocouples for measuring material surface temperature have been previously demonstrated on several material systems and in various hostile test environments. A well-developed thin film fabrication procedure utilizing shadow masking for patterning the sensors elements had produced thin films with sufficient durability for applications in high temperature and pressure environments that exist in air-breathing and hydrogen-fueled burner rig and engine test facilities. However, while shadow masking had been a reliable method for specimens with flat and gently curved surfaces, it had not been consistently reliable for use on test components with sharp contours. This work reports on the feasibility of utilizing photolithography processing for patterning thin film thermocouples. Because this patterning process required changes in the thin film deposition process from that developed for shadow masking, the effect of these changes on thin film adherence during burner rig testing was evaluated. In addition to the results of changing the patterning method, the effects on thin film adherence of other processes used in the thin film fabrication procedure is also presented.

A-SITE-AND/OR B-SITE-MODIFIED PBZRTIO3 MATERIALS AND (PB, SR, CA, BA, MG) (ZR, TI,NB, TA)O3 FILMS HAVING UTILITY IN FERROELECTRIC RANDOM ACCESS MEMORIES AND HIGH PERFORMANCE THIN FILM MICROACTUATORS

NASA Technical Reports Server (NTRS)

Bilodeau, Steven (Inventor); Baum, Thomas H. (Inventor); Roeder, Jeffrey F. (Inventor); Chen, Ing-Shin (Inventor)

2004-01-01

A modified PbZrTiO.sub.3 perovskite crystal material thin film, wherein the PbZrTiO.sub.3 perovskite crystal material includes crystal lattice A-sites and B-sites at least one of which is modified by the presence of a substituent selected from the group consisting of (i) A-site substituents consisting of Sr, Ca, Ba and Mg, and (ii) B-site substituents selected from the group consisting of Nb and Ta. The perovskite crystal thin film material may be formed by liquid delivery MOCVD from metalorganic precursors of the metal components of the thin film, to form PZT and PSZT, and other piezoelectric and ferroelectric thin film materials. The thin films of the invention have utility in non-volatile ferroelectric memory devices (NV-FeRAMs), and in microelectromechanical systems (MEMS) as sensor and/or actuator elements, e.g., high speed digital system actuators requiring low input power levels.

Recent progress in n-channel organic thin-film transistors.

PubMed

Wen, Yugeng; Liu, Yunqi

2010-03-26

Particular attention has been focused on n-channel organic thin-film transistors (OTFTs) during the last few years, and the potentially cost-effective circuitry-based applications in flexible electronics, such as flexible radiofrequency identity tags, smart labels, and simple displays, will benefit from this fast development. This article reviews recent progress in performance and molecular design of n-channel semiconductors in the past five years, and limitations and practicable solutions for n-channel OTFTs are dealt with from the viewpoint of OTFT constitution and geometry, molecular design, and thin-film growth conditions. Strategy methodology is especially highlighted with an aim to investigate basic issues in this field.

A molecular dynamics study on thin film liquid boiling characteristics under rapid linear boundary heating: Effect of liquid film thickness

NASA Astrophysics Data System (ADS)

Rabbi, Kazi Fazle; Tamim, Saiful Islam; Faisal, A. H. M.; Mukut, K. M.; Hasan, Mohammad Nasim

2017-06-01

This study is a molecular dynamics investigation of phase change phenomena i.e. boiling of thin liquid films subjected to rapid linear heating at the boundary. The purpose of this study is to understand the phase change heat transfer phenomena at nano scale level. In the simulation, a thin film of liquid argon over a platinum surface has been considered. The simulation domain herein is a three-phase system consisting of liquid and vapor argon atoms placed over a platinum wall. Initially the whole system is brought to an equilibrium state at 90 K and then the temperature of the bottom wall is increased to a higher temperature (250K) within a finite time interval. Four different liquid argon film thicknesses have been considered (3 nm, 4 nm, 5 nm and 6 nm) in this study. The boundary heating rate (40×109 K/s) is kept constant in all these cases. Variation in system temperature, pressure, net evaporation number, spatial number density of the argon region with time for different film thickness have been demonstrated and analyzed. The present study indicates that the pattern of phase transition may be significantly different (i.e. evaporation or explosive boiling) depending on the liquid film thickness. Among the four cases considered in the present study, explosive boiling has been observed only for the liquid films of 5nm and 6nm thickness, while for the other cases, evaporation take place.

Thin film encapsulation for flexible AM-OLED: a review

NASA Astrophysics Data System (ADS)

Park, Jin-Seong; Chae, Heeyeop; Chung, Ho Kyoon; In Lee, Sang

2011-03-01

Flexible organic light emitting diode (OLED) will be the ultimate display technology to customers and industries in the near future but the challenges are still being unveiled one by one. Thin-film encapsulation (TFE) technology is the most demanding requirement to prevent water and oxygen permeation into flexible OLED devices. As a polymer substrate does not offer the same barrier performance as glass, the TFE should be developed on both the bottom and top side of the device layers for sufficient lifetimes. This work provides a review of promising thin-film barrier technologies as well as the basic gas diffusion background. Topics include the significance of the device structure, permeation rate measurement, proposed permeation mechanism, and thin-film deposition technologies (Vitex system and atomic layer deposition (ALD)/molecular layer deposition (MLD)) for effective barrier films.

Single Source Precursors for Thin Film Solar Cells

NASA Technical Reports Server (NTRS)

Banger, Kulbinder K.; Hollingsworth, Jennifer A.; Harris, Jerry D.; Cowen, Jonathan; Buhro, William E.; Hepp, Aloysius F.

2002-01-01

The development of thin film solar cells on flexible, lightweight, space-qualified substrates provides an attractive cost solution to fabricating solar arrays with high specific power, (W/kg). The use of a polycrystalline chalcopyrite absorber layer for thin film solar cells is considered as the next generation photovoltaic devices. At NASA GRC we have focused on the development of new single source precursors (SSP) and their utility to deposit the chalcopyrite semi-conducting layer (CIS) onto flexible substrates for solar cell fabrication. The syntheses and thermal modulation of SSPs via molecular engineering is described. Thin-film fabrication studies demonstrate the SSPs can be used in a spray CVD (chemical vapor deposition) process, for depositing CIS at reduced temperatures, which display good electrical properties, suitable for PV (photovoltaic) devices.

Dewetting of thin films on flexible substrates via direct-write laser exposure

NASA Astrophysics Data System (ADS)

Ferrer, Anthony Jesus

Microelectromechanical systems (MEMS) have enabled a wide variety of technologies both in the consumer space and in industrial/research areas. At the market level, such devices advance by the invention and innovation of production techniques. Additionally, there has been increased demand for flexible versions of such MEMS devices. Thin film patterning, represents a key technology for the realization of such flexible electronics. Patterns and methods that can be directly written into the thin film allow for design modification on the fly with the need for harsh chemicals and long etching steps. Laser-induced dewetting has the potential to create patterns in thin films at both the microscopic and nanoscopic level without wasting deposited material. This thesis presents the first demonstration of high-speed direct-write patterning of metallic thin films that uses a laser-induced dewetting phenomenon to prevent material loss. The ability to build film material with this technique is explored using various scanning geometries. Finally, demonstrations of direct-write dewetting of a variety of thin films will be presented with special consideration for high melting point metals deposited upon polymer substrates.

Electrochemical Analysis of Conducting Polymer Thin Films

PubMed Central

Vyas, Ritesh N.; Wang, Bin

2010-01-01

Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting polymer, poly(p-phenylene vinylene) (PPV), in the preparation of a stable thin film via the LbL method. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize the ionic conductivity of the PPV multilayer films. The ionic conductivity of the films has been found to be dependent on the polymerization temperature. The film conductivity can be fitted to a modified Randle’s circuit. The circuit equivalent calculations are performed to provide the diffusion coefficient values. PMID:20480052

An investigation of material properties and tribological performance of magnetron sputtered thin film coatings

NASA Astrophysics Data System (ADS)

Singh, Harpal

This dissertation is divided into two categories based upon lubrication functionality and its application. The categories are: Dry film lubrication and Fluid film lubrication with thin film coatings. Thin film coatings examined in this work were deposited using closed field unbalanced magnetron sputtering and RF-DC coupled magnetron sputtering systems. In Dry/Solid film lubrication, the mechanical, structural and tribological properties of two Molybdenum disulphide (MoS2) based coatings are examined and evaluated. Among the two coatings, one coating is doped with Ti (Ti-MoS2) and the other is a combination of metal, lubricant and oxide (Sb2O3/Au - MoS2). These coatings are known to provide low friction in vacuum environments. The goal of this work was to evaluate friction and wear performance of MoS2 doped coatings in unidirectional and reciprocating sliding contact under different environmental conditions. Sliding contact results showed friction and wear dependence on temperature and humidity. The formation and removal of transfer films and the recrystallization and reorientation of basal layers on the steel counterface was observed as the mechanism for low friction. Structural analysis revealed a relationship between the microstructural properties and tribological performance. It was also observed that the addition of dopants (Ti, Au, Sb 2O3) improved the mechanical properties as compared to pure MoS2 coatings. Further, the rolling contact performance of the coatings was measured on a five ball on rod tribometer and a Thrust bearing tribometer under vacuum and air environments. The rolling contact experiments indicated that life of the rolling components depend on the amount of material present between the contacts. Fluid film lubrication with thin film coatings investigates the possibilities to improve the performance and durability of tribological components when oils and thin films are synergistically coupled. In this work, the ability of a Diamond Like Carbon

High mobility n-type organic thin-film transistors deposited at room temperature by supersonic molecular beam deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiarella, F., E-mail: fabio.chiarella@spin.cnr.it; Barra, M.; Ciccullo, F.

In this paper, we report on the fabrication of N,N′-1H,1H-perfluorobutil dicyanoperylenediimide (PDIF-CN{sub 2}) organic thin-film transistors by Supersonic Molecular Beam Deposition. The devices exhibit mobility up to 0.2 cm{sup 2}/V s even if the substrate is kept at room temperature during the organic film growth, exceeding by three orders of magnitude the electrical performance of those grown at the same temperature by conventional Organic Molecular Beam Deposition. The possibility to get high-mobility n-type transistors avoiding thermal treatments during or after the deposition could significantly extend the number of substrates suitable to the fabrication of flexible high-performance complementary circuits by using this compound.

Soft Magnetic Multilayered Thin Films for HF Applications

NASA Astrophysics Data System (ADS)

Loizos, George; Giannopoulos, George; Serletis, Christos; Maity, Tuhin; Roy, Saibal; Lupu, Nicoleta; Kijima, Hanae; Yamaguchi, Masahiro; Niarchos, Dimitris

Multilayered thin films from various soft magnetic materials were successfully prepared by magnetron sputtering in Ar atmosphere. The magnetic properties and microstructure were investigated. It is found that the films show good soft magnetic properties: magnetic coercivity of 1-10 Oe and saturation magnetization higher than 1T. The initial permeability of the films is greater than 300 and flattens up to 600 MHz. The multilayer thin film properties in combination with their easy, fast and reproducible fabrication indicate that they are potential candidates for high frequency applications.

Thin Film Ceramic Strain Sensor Development for High Temperature Environments

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Gonzalez, Jose M.; Laster, Kimala L.

2008-01-01

The need for sensors to operate in harsh environments is illustrated by the need for measurements in the turbine engine hot section. The degradation and damage that develops over time in hot section components can lead to catastrophic failure. At present, the degradation processes that occur in the harsh hot section environment are poorly characterized, which hinders development of more durable components, and since it is so difficult to model turbine blade temperatures, strains, etc, actual measurements are needed. The need to consider ceramic sensing elements is brought about by the temperature limits of metal thin film sensors in harsh environments. The effort at the NASA Glenn Research Center (GRC) to develop high temperature thin film ceramic static strain gauges for application in turbine engines is described, first in the fan and compressor modules, and then in the hot section. The near-term goal of this research effort was to identify candidate thin film ceramic sensor materials and provide a list of possible thin film ceramic sensor materials and corresponding properties to test for viability. A thorough literature search was conducted for ceramics that have the potential for application as high temperature thin film strain gauges chemically and physically compatible with the NASA GRCs microfabrication procedures and substrate materials. Test results are given for tantalum, titanium and zirconium-based nitride and oxynitride ceramic films.

Melting Behavior of Al/Pb/Sn/Al Multilayered Thin Films

NASA Astrophysics Data System (ADS)

Khan, Patan Yousaf; Devi, M. Manolata; Biswas, Krishanu

2015-09-01

Metals or alloy nanoparticles (NPs) have been reported to exhibit superheating on melting when coated with higher melting point material or embedded in a matrix. This is due to the suppression of the heterogeneous nucleation of the melt at the epitaxial interface. For 2D thin films, this necessary condition is not feasible because even if a thin film is sandwiched between higher melting temperature materials with coherent interfaces, the heterogeneous nucleation of melt is possible at various detects. However, it has earlier been reported that 2D thin films of the pure metal sandwiched by other materials can exhibit superheating by suppression of melt growth. In order to probe this effect in case of alloy thin films, the present investigation has been carried out on Pb/Sn multilayers sandwiched between Al layers. The present study shows that such sandwiched thin films prepared by accumulative roll bonding process cause the formation of biphasic NPs in the intermixed region of Pb and Sn. Al layers undergo severe plastic deformation, leading to the generation of dislocations and sub-grain boundaries. DSC (differential canning calorimeter) thermograms of the films indicate superheating of 3 K to 6 K (or 3 °C to 6 °C). Theoretical analysis using currently available literatures has been carried out to justify the finding in the present investigation.

Method for synthesizing thin film electrodes

DOEpatents

Boyle, Timothy J [Albuquerque, NM

2007-03-13

A method for making a thin-film electrode, either an anode or a cathode, by preparing a precursor solution using an alkoxide reactant, depositing multiple thin film layers with each layer approximately 500 1000 .ANG. in thickness, and heating the layers to above 600.degree. C. to achieve a material with electrochemical properties suitable for use in a thin film battery. The preparation of the anode precursor solution uses Sn(OCH.sub.2C(CH.sub.3).sub.3).sub.2 dissolved in a solvent in the presence of HO.sub.2CCH.sub.3 and the cathode precursor solution is formed by dissolving a mixture of (Li(OCH.sub.2C(CH.sub.3).sub.3)).sub.8 and Co(O.sub.2CCH.sub.3).H.sub.2O in at least one polar solvent.

Dewetting of Thin Polymer Films

NASA Astrophysics Data System (ADS)

Dixit, P. S.; Sorensen, J. L.; Kent, M.; Jeon, H. S.

2001-03-01

DEWETTING OF THIN POLYMER FILMS P. S. Dixit,(1) J. L. Sorensen,(2) M. Kent,(2) H. S. Jeon*(1) (1) Department of Petroleum and Chemical Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, jeon@nmt.edu (2) Department 1832, Sandia National Laboratories, Albuquerque, NM. Dewetting of thin polymer films is of technological importance for a variety of applications such as protective coatings, dielectric layers, and adhesives. Stable and smooth films are required for the above applications. Above the glass transition temperature (Tg) the instability of polymer thin films on a nonwettable substrate can be occurred. The dewetting mechanism and structure of polypropylene (Tg = -20 ^circC) and polystyrene (Tg = 100 ^circC) thin films is investigated as a function of film thickness (25 Åh < 250 Åand quenching temperature. Contact angle measurements are used in conjunction with optical microscope to check the surface homogeneity of the films. Uniform thin films are prepared by spin casting the polymer solutions onto silicon substrates with different contact angles. We found that the stable and unstable regions of the thin films as a function of the film thickness and quenching temperature, and then constructed a stability diagram for the dewetting of thin polymer films. We also found that the dewetting patterns of the thin films are affected substantially by the changes of film thickness and quenching temperature.

Commercial aspects of epitaxial thin film growth in outer space

NASA Technical Reports Server (NTRS)

Ignatiev, Alex; Chu, C. W.

1988-01-01

A new concept for materials processing in space exploits the ultra vacuum component of space for thin film epitaxial growth. The unique low earth orbit space environment is expected to yield 10 to the -14th torr or better pressures, semiinfinite pumping speeds and large ultra vacuum volume (about 100 cu m) without walls. These space ultra vacuum properties promise major improvement in the quality, unique nature, and the throughput of epitaxially grown materials especially in the area of semiconductors for microelectronics use. For such thin film materials there is expected a very large value added from space ultra vacuum processing, and as a result the application of the epitaxial thin film growth technology to space could lead to major commercial efforts in space.

New organic semiconductor thin film derived from p-toluidine monomer

NASA Astrophysics Data System (ADS)

Al-Hossainy, A. F.; Zoromba, M. Sh

2018-03-01

p-Toluidine was used as a precursor to synthesize new organic compound [(E)-4-methyl-N1-((E)-4-methyl-6-(p-tolylimino) cyclohex-3-en-1-ylidene)-N2-(p-tolyl) benzene-1,2-diamine] (MBD) by oxidative reaction via potassium dichromate as oxidizing agent at room temperature. Spin coater was used to fabricate nano-size crystalline thin film of the MBD with thickness 73 nm. The characterizations of the MBD powder and thin film have been described by various techniques including Fourier Transform Infrared (FT-IR), Mass Spectra, X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), UV-Visible measurements and Atomic Force Microscope (AFM). The results revealed that the MBD as an organic material is semi-crystalline containing benzenoid (Bensbnd Nsbnd Ben) and quinonoid (Quin = N = Quin) structures. Various optical constants such as refractive index (n), and the absorption index, (k) of the MBD thin film were determined. The effect of temperature on the electrical resistivity of MBD film was studied by a Keithley 6517B electrometer. The energy band gap value of the MBD thin film was found to be 2.24 eV. Thus, MBD is located in the semiconductor materials range. In addition, structural and optical mechanisms of MBD nanostructured thin film were investigated. The obtained results illustrate the possibility of controlling the organic semiconductor MBD thin film for the optoelectronic applications.

High index glass thin film processing for photonics and photovoltaic (PV) applications

NASA Astrophysics Data System (ADS)

Ogbuu, Okechukwu Anthony

To favorably compete with fossil-fuel technology, the greatest challenge for thin film solar-cells is to improve efficiency and reduce material cost. Thickness scaling to thin film reduces material cost but affects the light absorption in the cells; therefore a concept that traps incident photons and increases its optical path length is needed to boost absorption in thin film solar cells. One approach is the integration of low symmetric gratings (LSG), using high index material, on either the front-side or backside of 30 um thin c-Si cells. In this study, Multicomponent TeO2--Bi2O 3--ZnO (TBZ) glass thin films were prepared using RF magnetron sputtering under different oxygen flow rates. The influences of oxygen flow rate on the structural and optical properties of the resulting thin films were investigated. The structural origin of the optical property variation was studied using X-ray diffraction, X-ray photoelectron spectroscopy, Raman Spectroscopy, and transmission electron microscopy. The results indicate that TBZ glass thin film is a suitable material for front side LSG material photovoltaic and photonics applications due to their amorphous nature, high refractive index (n > 2), broad band optical transparency window, low processing temperature. We developed a simple maskless method to pattern sputtered tellurite based glass thin films using unconventional agarose hydrogel mediated wet etching. Conventional wet etching process, while claiming low cost and high throughput, suffers from reproducibility and pattern fidelity issues due to the isotropic nature of wet chemical etching when applied to glasses and polymers. This method overcomes these challenges by using an agarose hydrogel stamp to mediate a conformal etching process. In our maskless method, agarose hydrogel stamps are patterned following a standard soft lithography and replica molding process from micropatterned masters and soaked in a chemical etchant. The micro-scale features on the stamp are

Molecular organization in MAPLE-deposited conjugated polymer thin films and the implications for carrier transport characteristics

DOE PAGES

Dong, Ban Xuan; Li, Anton; Strzalka, Joseph; ...

2016-09-18

The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. We found that the MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π-π stacking, and conjugated backbone directions. Furthermore, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. In spite of the seemingly unfavorable molecular orientations andmore » the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 meV versus 54 meV) to those reported in the literature for high mobility polymers.« less

Molecular organization in MAPLE-deposited conjugated polymer thin films and the implications for carrier transport characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Ban Xuan; Li, Anton; Strzalka, Joseph

The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. We found that the MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π-π stacking, and conjugated backbone directions. Furthermore, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. In spite of the seemingly unfavorable molecular orientations andmore » the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 meV versus 54 meV) to those reported in the literature for high mobility polymers.« less

Ultrahigh-Performance Cu2ZnSnS4 Thin Film and Its Application in Microscale Thin-Film Lithium-Ion Battery: Comparison with SnO2.

PubMed

Lin, Jie; Guo, Jianlai; Liu, Chang; Guo, Hang

2016-12-21

To develop a high-performance anode for thin-film lithium-ion batteries (TFBs, with a total thickness on the scale of micrometers), a Cu 2 ZnSnS 4 (CZTS) thin film is fabricated by magnetron sputtering and exhibits an ultrahigh performance of 950 mAh g -1 even after 500 cycles, which is the highest among the reported CZTS for lithium storage so far. The characterization and electrochemical tests reveal that the thin-film structure and additional reactions both contribute to the excellent properties. Furthermore, the microscale TFBs with effective footprints of 0.52 mm 2 utilizing the CZTS thin film as anode are manufactured by microfabrication techniques, showing superior capability than the analogous TFBs with the SnO 2 thin film as anode. This work demonstrates the advantages of exploiting thin-film electrodes and novel materials into micropower sources by electronic manufacture methods.

Temperature stabilized effusion cell evaporation source for thin film deposition and molecular-beam epitaxy

NASA Astrophysics Data System (ADS)

Tiedje, H. F.; Brodie, D. E.

2000-05-01

A simple effusion cell evaporation source for thin film deposition and molecular-beam epitaxy is described. The source consists of a crucible with a thermocouple temperature sensor heated by a resistive crucible heater. Radiation heat transfer from the crucible to the thermocouple produces a consistent and reproducible thermocouple temperature for a given crucible temperature, without direct contact between the thermocouple and the crucible. The thermocouple temperature is somewhat less than the actual crucible temperature because of heat flow from the thermocouple junction along the thermocouple lead wires. In a typical case, the thermocouple temperature is 1007 °C while the crucible is at 1083 °C. The crucible temperature stability is estimated from the measured sensitivity of the evaporation rate of indium to temperature, and the observed variations in the evaporation rate for a fixed thermocouple temperature. The crucible temperature peak-to-peak variation over a one hour period is 1.2 °C. Machined molybdenum crucibles were used in the indium and copper sources for depositing CuInSe2 thin films for solar cells.

Polycrystalline Thin Film Photovoltaics: Research, Development, and Technologies: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ullal, H. S.; Zweibel, K.; von Roedern, B.

2002-05-01

II-VI binary thin-film solar cells based on cadmium telluride (CdTe) and I-III-VI ternary thin-film solar cells based on copper indium diselenide (CIS) and related materials have been the subject of intense research and development in the past few years. Substantial progress has been made thus far in the area of materials research, device fabrication, and technology development, and numerous applications based on CdTe and CIS have been deployed worldwide. World record efficiency of 16.5% has been achieved by NREL scientists for a thin-film CdTe solar cell using a modified device structure. Also, NREL scientists achieved world-record efficiency of 21.1% formore » a thin-film CIGS solar cell under a 14X concentration and AM1.5 global spectrum. When measured under a AM1.5 direct spectrum, the efficiency increases to 21.5%. Pathways for achieving 25% efficiency for tandem polycrystalline thin-film solar cells are elucidated. R&D issues relating to CdTe and CIS are reported in this paper, such as contact stability and accelerated life testing in CdTe, and effects of moisture ingress in thin-film CIS devices. Substantial technology development is currently under way, with various groups reporting power module efficiencies in the range of 7.0% to 12.1% and power output of 40.0 to 92.5 W. A number of lessons learned during the scale-up activities of the technology development for fabrication of thin-film power modules are discussed. The major global players actively involved in the technology development and commercialization efforts using both rigid and flexible power modules are highlighted.« less

Growth and optical property characterization of textured barium titanate thin films for photonic applications

NASA Astrophysics Data System (ADS)

Dicken, Matthew J.; Diest, Kenneth; Park, Young-Bae; Atwater, Harry A.

2007-03-01

We have investigated the growth of barium titanate thin films on bulk crystalline and amorphous substrates utilizing biaxially oriented template layers. Ion beam-assisted deposition was used to grow thin, biaxially textured, magnesium oxide template layers on amorphous and silicon substrates. Growth of highly oriented barium titanate films on these template layers was achieved by molecular beam epitaxy using a layer-by-layer growth process. Barium titanate thin films were grown in molecular oxygen and in the presence of oxygen radicals produced by a 300 W radio frequency plasma. We used X-ray and in situ reflection high-energy electron diffraction (RHEED) to analyze the structural properties and show the predominantly c-oriented grains in the films. Variable angle spectroscopic ellipsometry was used to analyze and compare the optical properties of the thin films grown with and without oxygen plasma. We have shown that optical quality barium titanate thin films, which show bulk crystal-like properties, can be grown on any substrate through the use of biaxially oriented magnesium oxide template layers.

Magnetic damping phenomena in ferromagnetic thin-films and multilayers

NASA Astrophysics Data System (ADS)

Azzawi, S.; Hindmarch, A. T.; Atkinson, D.

2017-11-01

Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.

Thin film superconductor magnetic bearings

DOEpatents

Weinberger, Bernard R.

1995-12-26

A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

Combinatorial screening of organic electronic materials: thin film stability

NASA Astrophysics Data System (ADS)

Chattopadhyay, Santanu; Carson Meredith, J.

2005-01-01

Dewetting of thin polymeric semiconducting-insulating (and conducting-insulating) bilayers is a serious fundamental problem facing the fabrication of organic electronic devices such as transistors, light-emitting diodes and supercapacitors. This paper describes a high-throughput characterization method that utilizes orthogonal thickness-gradient libraries of the bilayer components poly(3-octylthiophene) (semiconductor) and poly(styrene) (insulator). The technique allows simultaneous observation of hundreds of combinations of thicknesses and has permitted rapid discovery of a previously-unknown VDW instability transition. We observe that the onset of VDW instability in the PS-P3OT bilayer is a complex function of P3OT thickness that cannot be predicted by Hamaker constant models for free energy. At low P3OT thickness, the semiconductor acts to stabilize the PS insulator. But above a P3OT thickness of 175 nm, this behaviour is switched and P3OT destabilizes the PS. These thickness-dependent effects are correlated very well with dramatic transitions in P3OT optical spectra and the P3OT-AFM tip interaction forces. This unusual behaviour places critical limitations on practical device thicknesses and interfacial combinations, and points to the need for a thin-film stability theory that accounts for thickness-dependent molecular-electronic effects.

Magnetic hysteresis measurements of thin films under isotropic stress.

NASA Astrophysics Data System (ADS)

Holland, Patrick; Dubey, Archana; Geerts, Wilhelmus

2000-10-01

Nowadays, ferromagnetic thin films are widely applied in devices for information technology (credit cards, video recorder tapes, floppies, hard disks) and sensors (air bags, anti-breaking systems, navigation systems). Thus, with the increase in the use of magnetic media continued investigation of magnetic properties of materials is necessary to help in determining the useful properties of materials for new or improved applications. We are currently interested in studying the effect of applied external stress on Kerr hysteresis curves of thin magnetic films. The Ni and NiFe films were grown using DC magnetron sputtering with Ar as the sputter gas (pAr=4 mTorr; Tsub=55-190 C). Seed and cap layers of Ti were used on all films for adhesion and oxidation protection, respectively. A brass membrane pressure cell was designed to apply in-plane isotropic stress to thin films. In this pressure cell, gas pressure is used to deform a flexible substrate onto which a thin magnetic film has been sputtered. The curvature of the samples could be controlled by changing the gas pressure to the cell. Magneto-Optical in-plane hysteresis curves at different values of strain were measured. The results obtained show that the stress sensitivity is dependent on the film thickness. For the 500nm NiFe films, the coercivity strongly decreased as a function of the applied stress.

Preparation and Optical Properties of GeBi Films by Using Molecular Beam Epitaxy Method

NASA Astrophysics Data System (ADS)

Zhang, Dainan; Liao, Yulong; Jin, Lichuan; Wen, Qi-Ye; Zhong, Zhiyong; Wen, Tianlong; Xiao, John Q.

2017-12-01

Ge-based alloys have drawn great interest as promising materials for their superior visible to infrared photoelectric performances. In this study, we report the preparation and optical properties of germanium-bismuth (Ge1-xBix) thin films by using molecular beam epitaxy (MBE). GeBi thin films belong to the n-type conductivity semiconductors, which have been rarely reported. With the increasing Bi-doping content from 2 to 22.2%, a series of Ge1-xBix thin film samples were obtained and characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. With the increase of Bi content, the mismatch of lattice constants increases, and the GeBi film shifts from direct energy band-gaps to indirect band-gaps. The moderate increase of Bi content reduces optical reflectance and promotes the transmittance of extinction coefficient in infrared wavelengths. The absorption and transmittance of GeBi films in THz band increase with the increase of Bi contents.

Novel organic semiconductors and a high capacitance gate dielectric for organic thin film transistors

NASA Astrophysics Data System (ADS)

Cai, Xiuyu

2007-12-01

Organic semiconductors are attracting more and more interest as a promising set of materials in the field of electronics research. This thesis focused on several new organic semiconductors and a novel high-kappa dielectric thin film (SrTiO3), which are two essential parts in Organic Thin Film Transistors (OTFTs). Structure and morphology of thin films of tricyanovinyl capped oligothiophenes were studied using atomic force microscopy and x-ray diffraction. Thin film transistors of one compound exhibited a reasonable electron mobility of 0.02 cm2/Vs. Temperature dependent measurements on the thin film transistor based on this compound revealed shallow trap states that were interpreted in terms of a multiple trap and release model. Moreover, inversion of the majority charge carrier type from electrons to holes was observed when the number of oligothiophene rings increased to six and ambipolar transport behavior was observed for tricyanovinyl sexithiophene. Another interesting organic semiconductor compound is the fluoalkylquarterthiophene, which showed ambipolar transport and large hysteresis in the transfer curve. Due to the bistable state at floating gate, the thin film transistor was exploited to study non-volatile floating gate memory effects. The temperature dependence of the retention time for this memory device revealed that the electron trapping was an activated process. Following the earlier work on hybrid acene-thiophene organic semiconductors, new compounds with similar structure were studied to reveal the mechanism of the air-stability exhibited by some compounds. They all formed highly crystalline thin films and showed reasonable device performances which are well correlated with the molecular structures, thin film microstructures, and solid state packing. The most air-stable compound had no observable degradation with exposure to air for 15 months. SrTiO3 was developed to be employed in OTFTs. Optimization of thin film growth was performed using reactive

Nanosphere lithography applied to magnetic thin films

NASA Astrophysics Data System (ADS)

Gleason, Russell

Magnetic nanostructures have widespread applications in many areas of physics and engineering, and nanosphere lithography has recently emerged as promising tool for the fabrication of such nanostructures. The goal of this research is to explore the magnetic properties of a thin film of ferromagnetic material deposited onto a hexagonally close-packed monolayer array of polystyrene nanospheres, and how they differ from the magnetic properties of a typical flat thin film. The first portion of this research focuses on determining the optimum conditions for depositing a monolayer of nanospheres onto chemically pretreated silicon substrates (via drop-coating) and the subsequent characterization of the deposited nanosphere layer with scanning electron microscopy. Single layers of permalloy (Ni80Fe20) are then deposited on top of the nanosphere array via DC magnetron sputtering, resulting in a thin film array of magnetic nanocaps. The coercivities of the thin films are measured using a home-built magneto-optical Kerr effect (MOKE) system in longitudinal arrangement. MOKE measurements show that for a single layer of permalloy (Py), the coercivity of a thin film deposited onto an array of nanospheres increases compared to that of a flat thin film. In addition, the coercivity increases as the nanosphere size decreases for the same deposited layer. It is postulated that magnetic exchange decoupling between neighboring nanocaps suppresses the propagation of magnetic domain walls, and this pinning of the domain walls is thought to be the primary source of the increase in coercivity.

Ceramic Composite Thin Films

NASA Technical Reports Server (NTRS)

Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor); Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor)

2013-01-01

A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

Thin-film metal coated insulation barrier in a Josephson tunnel junction. [Patent application

DOEpatents

Hawkins, G.A.; Clarke, J.

1975-10-31

A highly stable, durable, and reproducible Josephson tunnel junction consists of a thin-film electrode of a hard superconductor, a thin oxide insulation layer over the electrode constituting a Josephson tunnel junction barrier, a thin-film layer of stabilizing metal over the barrier, and a second thin-film hard superconductive electrode over the stabilizing film. The thin stabilizing metal film is made only thick enough to limit penetration of the electrode material through the insulation layer so as to prevent a superconductive short.

Antimicrobial activity of biopolymer-antibiotic thin films fabricated by advanced pulsed laser methods

NASA Astrophysics Data System (ADS)

Cristescu, R.; Popescu, C.; Dorcioman, G.; Miroiu, F. M.; Socol, G.; Mihailescu, I. N.; Gittard, S. D.; Miller, P. R.; Narayan, R. J.; Enculescu, M.; Chrisey, D. B.

2013-08-01

We report on thin film deposition by matrix assisted pulsed laser evaporation (MAPLE) of two polymer-drug composite thin film systems. A pulsed KrF* excimer laser source (λ = 248 nm, τ = 25 ns, ν = 10 Hz) was used to deposit composite thin films of poly(D,L-lactide) (PDLLA) containing several gentamicin concentrations. FTIR spectroscopy was used to demonstrate that MAPLE-transferred materials exhibited chemical structures similar to those of drop cast materials. Scanning electron microscopy data indicated that MAPLE may be used to fabricate thin films of good morphological quality. The activity of PDLLA-gentamicin composite thin films against Staphylococcus aureus bacteria was demonstrated using drop testing. The influence of drug concentration on microbial viability was also assessed. Our studies indicate that polymer-drug composite thin films prepared by MAPLE may be used to impart antimicrobial activity to implants, medical devices, and other contact surfaces.

Reflow dynamics of thin patterned viscous films

NASA Astrophysics Data System (ADS)

Leveder, T.; Landis, S.; Davoust, L.

2008-01-01

This letter presents a study of viscous smoothening dynamics of a nanopatterned thin film. Ultrathin film manufacturing processes appearing to be a key point of nanotechnology engineering and numerous studies have been recently led in order to exhibit driving parameters of this transient surface motion, focusing on time scale accuracy method. Based on nanomechanical analysis, this letter shows that controlled shape measurements provided much more detailed information about reflow mechanism. Control of reflow process of any complex surface shape, or measurement of material parameter as thin film viscosity, free surface energy, or even Hamaker constant are therefore possible.

Thin-Film Ceramic Thermocouples Fabricated and Tested

NASA Technical Reports Server (NTRS)

Wrbanek, John D.; Fralick, Gustave C.; Farmer, Serene C.; Sayir, Ali; Gregory, Otto J.; Blaha, Charles A.

2004-01-01

The Sensors and Electronics Technology Branch of the NASA Glenn Research Center is developing thin-film-based sensors for surface measurement in propulsion system research. Thin-film sensors do not require special machining of the components on which they are mounted, and they are considerably thinner than wire- or foil-based sensors. One type of sensor being advanced is the thin-film thermocouple, specifically for applications in high-temperature combustion environments. Ceramics are being demonstrated as having the potential to meet the demands of thin-film thermocouples in advanced aerospace environments. The maximum-use temperature of noble metal thin-film thermocouples, 1500 C (2700 F), may not be adequate for components used in the increasingly harsh conditions of advanced aircraft and next-generation launch vehicles. Ceramic-based thermocouples are known for their high stability and robustness at temperatures exceeding 1500 C, but are typically in the form of bulky rods or probes. As part of ASTP, Glenn's Sensors and Electronics Technology Branch is leading an in-house effort to apply ceramics as thin-film thermocouples for extremely high-temperature applications as part of ASTP. Since the purity of the ceramics is crucial for the stability of the thermocouples, Glenn's Ceramics Branch and Case Western Reserve University are developing high-purity ceramic sputtering targets for fabricating high-temperature sensors. Glenn's Microsystems Fabrication Laboratory, supported by the Akima Corporation, is using these targets to fabricate thermocouple samples for testing. The first of the materials used were chromium silicide (CrSi) and tantalum carbide (TaC). These refractory materials are expected to survive temperatures in excess of 1500 C. Preliminary results indicate that the thermoelectric voltage output of a thin-film CrSi versus TaC thermocouple is 15 times that of the standard type R (platinum-rhodium versus platinum) thermocouple, producing 20 mV with a 200

Thin film dielectric composite materials

DOEpatents

Jia, Quanxi; Gibbons, Brady J.; Findikoglu, Alp T.; Park, Bae Ho

2002-01-01

A dielectric composite material comprising at least two crystal phases of different components with TiO.sub.2 as a first component and a material selected from the group consisting of Ba.sub.1-x Sr.sub.x TiO.sub.3 where x is from 0.3 to 0.7, Pb.sub.1-x Ca.sub.x TiO.sub.3 where x is from 0.4 to 0.7, Sr.sub.1-x Pb.sub.x TiO.sub.3 where x is from 0.2 to 0.4, Ba.sub.1-x Cd.sub.x TiO.sub.3 where x is from 0.02 to 0.1, BaTi.sub.1-x Zr.sub.x O.sub.3 where x is from 0.2 to 0.3, BaTi.sub.1-x Sn.sub.x O.sub.3 where x is from 0.15 to 0.3, BaTi.sub.1-x Hf.sub.x O.sub.3 where x is from 0.24 to 0.3, Pb.sub.1-1.3x La.sub.x TiO.sub.3+0.2x where x is from 0.23 to 0.3, (BaTiO.sub.3).sub.x (PbFeo.sub.0.5 Nb.sub.0.5 O.sub.3).sub.1-x where x is from 0.75 to 0.9, (PbTiO.sub.3).sub.- (PbCo.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.1 to 0.45, (PbTiO.sub.3).sub.x (PbMg.sub.0.5 W.sub.0.5 O.sub.3).sub.1-x where x is from 0.2 to 0.4, and (PbTiO.sub.3).sub.x (PbFe.sub.0.5 Ta.sub.0.5 O.sub.3).sub.1-x where x is from 0 to 0.2, as the second component is described. The dielectric composite material can be formed as a thin film upon suitable substrates.

Influence of the side chain and substrate on polythiophene thin film surface, bulk, and buried interfacial structures.

PubMed

Xiao, Minyu; Jasensky, Joshua; Zhang, Xiaoxian; Li, Yaoxin; Pichan, Cayla; Lu, Xiaolin; Chen, Zhan

2016-08-10

The molecular structures of organic semiconducting thin films mediate the performance of various devices composed of such materials. To fully understand how the structures of organic semiconductors alter on substrates due to different polymer side chains and different interfacial interactions, thin films of two kinds of polythiophene derivatives with different side-chains, poly(3-hexylthiophene) (P3HT) and poly(3-potassium-6-hexanoate thiophene) (P3KHT), were deposited and compared on various surfaces. A combination of analytical tools was applied in this research: contact angle goniometry and X-ray photoelectron spectroscopy (XPS) were used to characterize substrate dielectric surfaces with varied hydrophobicity for polymer film deposition; X-ray diffraction and UV-vis spectroscopy were used to examine the polythiophene film bulk structure; sum frequency generation (SFG) vibrational spectroscopy was utilized to probe the molecular structures of polymer film surfaces in air and buried solid/solid interfaces. Both side-chain hydrophobicity and substrate hydrophobicity were found to mediate the crystallinity of the polythiophene film, as well as the orientation of the thiophene ring within the polymer backbone at the buried polymer/substrate interface and the polymer thin film surface in air. For the same type of polythiophene film deposited on different substrates, a more hydrophobic substrate surface induced thiophene ring alignment with the surface normal at both the buried interface and on the surface in air. For different films (P3HT vs. P3KHT) deposited on the same dielectric substrate, a more hydrophobic polythiophene side chain caused the thiophene ring to align more towards the surface at the buried polymer/substrate interface and on the surface in air. We believe that the polythiophene surface, bulk, and buried interfacial molecular structures all influence the hole mobility within the polythiophene film. Successful characterization of an organic conducting

Exciton-phonon coupling in diindenoperylene thin films

NASA Astrophysics Data System (ADS)

Heinemeyer, U.; Scholz, R.; Gisslén, L.; Alonso, M. I.; Ossó, J. O.; Garriga, M.; Hinderhofer, A.; Kytka, M.; Kowarik, S.; Gerlach, A.; Schreiber, F.

2008-08-01

We investigate exciton-phonon coupling and exciton transfer in diindenoperylene (DIP) thin films on oxidized Si substrates by analyzing the dielectric function determined by variable-angle spectroscopic ellipsometry. Since the molecules in the thin-film phase form crystallites that are randomly oriented azimuthally and highly oriented along the surface normal, DIP films exhibit strongly anisotropic optical properties with uniaxial symmetry. This anisotropy can be determined by multiple sample analysis. The thin-film spectrum is compared with a monomer spectrum in solution, which reveals similar vibronic subbands and a Huang-Rhys parameter of S≈0.87 for an effective internal vibration at ℏωeff=0.17eV . However, employing these parameters the observed dielectric function of the DIP films cannot be described by a pure Frenkel exciton model, and the inclusion of charge-transfer (CT) states becomes mandatory. A model Hamiltonian is parametrized with density-functional theory calculations of single DIP molecules and molecule pairs in the stacking geometry of the thin-film phase, revealing the vibronic coupling constants of DIP in its excited and charged states together with electron and hole transfer integrals along the stack. From a fit of the model calculation to the observed dielectric tensor, we find the lowest CT transition E00CT at 0.26±0.05eV above the neutral molecular excitation energy E00F , which is an important parameter for device applications.

Fabrication of Meso-Porous Sintered Metal Thin Films by Selective Etching of Silica Based Sacrificial Template

PubMed Central

Dumée, Ludovic F.; She, Fenghua; Duke, Mikel; Gray, Stephen; Hodgson, Peter; Kong, Lingxue

2014-01-01

Meso-porous metal materials have enhanced surface energies offering unique surface properties with potential applications in chemical catalysis, molecular sensing and selective separation. In this paper, commercial 20 nm diameter metal nano-particles, including silver and copper were blended with 7 nm silica nano-particles by shear mixing. The resulted powders were cold-sintered to form dense, hybrid thin films. The sacrificial silica template was then removed by selective etching in 12 wt% hydrofluoric acid solutions for 15 min to reveal a purely metallic meso-porous thin film material. The impact of the initial silica nano-particle diameter (7–20 nm) as well as the sintering pressure (5–20 ton·m−2) and etching conditions on the morphology and properties of the final nano-porous thin films were investigated by porometry, pyknometery, gas and liquid permeation and electron microscopy. Furthermore, the morphology of the pores and particle aggregation during shear mixing were assessed through cross-sectioning by focus ion beam milling. It is demonstrated that meso-pores ranging between 50 and 320 nm in average diameter and porosities up to 47% can be successfully formed for the range of materials tested. PMID:28344241

The Chemical Vapor Deposition of Thin Metal Oxide Films

NASA Astrophysics Data System (ADS)

Laurie, Angus Buchanan

1990-01-01

Chemical vapor deposition (CVD) is an important method of preparing thin films of materials. Copper (II) oxide is an important p-type semiconductor and a major component of high T_{rm c} superconducting oxides. By using a volatile copper (II) chelate precursor, copper (II) bishexafluoroacetylacetonate, it has been possible to prepare thin films of copper (II) oxide by low temperature normal pressure metalorganic chemical vapor deposition. In the metalorganic CVD (MOCVD) production of oxide thin films, oxygen gas saturated with water vapor has been used mainly to reduce residual carbon and fluorine content. This research has investigated the influence of water-saturated oxygen on the morphology of thin films of CuO produced by low temperature chemical vapor deposition onto quartz, magnesium oxide and cubic zirconia substrates. ZnO is a useful n-type semiconductor material and is commonly prepared by the MOCVD method using organometallic precursors such as dimethyl or diethylzinc. These compounds are difficult to handle under atmospheric conditions. In this research, thin polycrystalline films of zinc oxide were grown on a variety of substrates by normal pressure CVD using a zinc chelate complex with zinc(II) bishexafluoroacetylacetonate dihydrate (Zn(hfa)_2.2H _2O) as the zinc source. Zn(hfa) _2.2H_2O is not moisture - or air-sensitive and is thus more easily handled. By operating under reduced-pressure conditions (20-500 torr) it is possible to substantially reduce deposition times and improve film quality. This research has investigated the reduced-pressure CVD of thin films of CuO and ZnO. Sub-micron films of tin(IV) oxide (SnO _2) have been grown by normal pressure CVD on quartz substrates by using tetraphenyltin (TPT) as the source of tin. All CVD films were characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA).

Thin film seeds for melt processing textured superconductors for practical applications

DOEpatents

Veal, Boyd W.; Paulikas, Arvydas; Balachandran, Uthamalingam; Zhong, Wei

1999-01-01

A method of fabricating bulk superconducting material such as RBa.sub.2 Cu.sub.3 O.sub.7-.delta. where R is La or Y comprising depositing a thin epitaxially oriented film of Nd or Sm (123) on an oxide substrate. The powder oxides of RBa.sub.2 Cu.sub.3 O.sub.7-.delta. or oxides and/or carbonates of R and Ba and Cu present in mole ratios to form RBa.sub.2 Cu.sub.3 O.sub.7-.delta., where R is Y or La are heated, in physical contact with the thin film of Nd or Sm (123) on the oxide substrate to a temperature sufficient to form a liquid phase in the oxide or carbonate mixture while maintaining the thin film solid to grow a large single domain 123 superconducting material. Then the material is cooled. The thin film is between 200 .ANG. and 2000 .ANG.. A construction prepared by the method is also disclosed.

Thin film seeds for melt processing textured superconductors for practical applications

DOEpatents

Veal, B.W.; Paulikas, A.; Balachandran, U.; Zhong, W.

1999-02-09

A method of fabricating bulk superconducting material such as RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} where R is La or Y comprising depositing a thin epitaxially oriented film of Nd or Sm (123) on an oxide substrate is disclosed. The powder oxides of RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} or oxides and/or carbonates of R and Ba and Cu present in mole ratios to form RBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}, where R is Y or La are heated, in physical contact with the thin film of Nd or Sm (123) on the oxide substrate to a temperature sufficient to form a liquid phase in the oxide or carbonate mixture while maintaining the thin film solid to grow a large single domain 123 superconducting material. Then the material is cooled. The thin film is between 200 {angstrom} and 2000 {angstrom}. A construction prepared by the method is also disclosed.

Investigations of Si Thin Films as Anode of Lithium-Ion Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Qingliu; Shi, Bing; Bareño, Javier

Amorphous silicon thin films having various thicknesses were investigated as a negative electrode material for lithium-ion batteries. Electrochemical characterization of the 20 nm thick thin silicon film revealed a very low first cycle Coulombic efficiency, which can be attributed to the silicon oxide layer formed on both the surface of the as-deposited Si thin film and the interface between the Si and the substrate. Among the investigated films, the 100 nm Si thin film demonstrated the best performance in terms of first cycle efficiency and cycle life. Observations from scanning electron microscopy demonstrated that the generation of cracks was inevitablemore » in the cycled Si thin films, even as the thickness of the film was as little as 20 nm, which was not predicted by previous modeling work. However, the cycling performance of the 20 and 100 nm silicon thin films was not detrimentally affected by these cracks. The poor capacity retention of the 1 mu m silicon thin film was attributed to the delamination.« less

Controllable film densification and interface flatness for high-performance amorphous indium oxide based thin film transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ou-Yang, Wei, E-mail: OUYANG.Wei@nims.go.jp, E-mail: TSUKAGOSHI.Kazuhito@nims.go.jp; Mitoma, Nobuhiko; Kizu, Takio

2014-10-20

To avoid the problem of air sensitive and wet-etched Zn and/or Ga contained amorphous oxide transistors, we propose an alternative amorphous semiconductor of indium silicon tungsten oxide as the channel material for thin film transistors. In this study, we employ the material to reveal the relation between the active thin film and the transistor performance with aid of x-ray reflectivity study. By adjusting the pre-annealing temperature, we find that the film densification and interface flatness between the film and gate insulator are crucial for achieving controllable high-performance transistors. The material and findings in the study are believed helpful for realizingmore » controllable high-performance stable transistors.« less

Water-Based Peeling of Thin Hydrophobic Films

NASA Astrophysics Data System (ADS)

Khodaparast, Sepideh; Boulogne, François; Poulard, Christophe; Stone, Howard A.

2017-10-01

Inks of permanent markers and waterproof cosmetics create elastic thin films upon application on a surface. Such adhesive materials are deliberately designed to exhibit water-repellent behavior. Therefore, patterns made up of these inks become resistant to moisture and cannot be cleaned by water after drying. However, we show that sufficiently slow dipping of such elastic films, which are adhered to a substrate, into a bath of pure water allows for complete removal of the hydrophobic coatings. Upon dipping, the air-water interface in the bath forms a contact line on the substrate, which exerts a capillary-induced peeling force at the edge of the hydrophobic thin film. We highlight that this capillary peeling process is more effective at lower velocities of the air-liquid interface and lower viscosities. Capillary peeling not only removes such thin films from the substrate but also transfers them flawlessly onto the air-water interface.

Spectroscopic investigation of the chemical and electronic properties of chalcogenide materials for thin-film optoelectronic devices

NASA Astrophysics Data System (ADS)

Horsley, Kimberly Anne

Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials. For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe 2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These techniques enabled the investigation of the chemical and electronic structure of the materials, both at the surface and towards the bulk. CdS/Cu(In,Ga)Se2 thin-films produced from the roll-to-roll, ambient pressure, Nanosolar industrial line were studied. While record-breaking efficiency cells are usually prepared in high-vacuum (HV) or ultra-high vacuum (UHV) environments, these samples demonstrate competitive mass-production efficiency without the high-cost deposition environment. We found relatively low levels of C contaminants, limited Na and Se oxidation, and a S-Se intermixing at the CdS/CIGSe interface. The surface band gap compared closely to previously investigated CIGSe thin-films deposited under vacuum, illustrating that roll-to-roll processing is a promising and less-expensive alternative for solar cell production. An alternative deposition process for CuInSe2 was also studied, in collaboration with the University of Luxembourg. CuInSe2 absorbers were prepared with varying Cu content and surface treatments to investigate the potential to produce an absorber with a Cu-rich bulk and Cu-poor surface. This is desired to combine the bulk characteristics of reduced defects and larger grains in Cu-rich films, while maintaining

Thin film coatings for space electrical power system applications

NASA Technical Reports Server (NTRS)

Gulino, Daniel A.

1989-01-01

This paper examines some of the ways in which thin film coatings can play a role in aerospace applications. Space systems discussed include photovoltaic and solar dynamic electric power generation systems, including applications in environmental protection, thermal energy storage, and radiator emittance enhancement. Potential applications of diamondlike films to both atmospheric and space based systems are examined. Also, potential uses of thin films of the recently discovered high-temperature superconductive materials are discussed.

Thin film coatings for space electrical power system applications

NASA Technical Reports Server (NTRS)

Gulino, Daniel A.

1988-01-01

This paper examines some of the ways in which thin film coatings can play a role in aerospace applications. Space systems discussed include photovoltaic and solar dynamic electric power generation systems, including applications in environmental protection, thermal energy storage, and radiator emittance enhancement. Potential applications of diamondlike films to both atmospheric and space based systems are examined. Also, potential uses of thin films of the recently discovered high-temperature superconductive materials are discussed.

Formation and photopatterning of nanoporous titania thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Oun-Ho; Cheng, Joy Y.; Kim, Hyun Suk

2007-06-04

Photopatternable nanoporous titania thin films were generated from mixtures of an organic diblock copolymer, poly(styrene-b-ethylene oxide) (PS-b-PEO), and an oligomeric titanate (OT) prepared from a chelated titanium isopropoxide. The PS-b-PEO templates well-defined microdomains in thin films of the mixtures, which upon thermal treatment at 450 deg. C, become nanopores in titania. Average pore size and porosity are controlled by the molecular weight and loading level of the PS-b-PEO, respectively. Patterns of nanoporous titania were created by selectively exposing UV light on the mixture films. The UV irradiation destroys the chelating bond and induces the cross-linking reaction of the OT. Subsequentmore » wet development followed by thermal treatment gives patterned nanoporous films of anatase phase titania.« less

Thin Films and Interfaces of AN Organic Semiconductor: Perylenetetracarboxylic Dianhydride

NASA Astrophysics Data System (ADS)

Hirose, Yutaka

Structural and electronic properties of thin films of an archetype organic molecular semiconductor, 3,4,9,10 -perylenetetracarboxylic dianhydride, (PTCDA) and of their interfaces are investigated. The first part of the thesis focuses on the growth of PTCDA thin films on graphite and GaAs. Molecular order in the direction parallel to the substrate is found to depend critically on the substrate surface properties, as revealed by marked differences in the crystallinity of films grown on graphite and Se-passivated GaAs surfaces (long range order), on the c(4 x 4) GaAs surface (medium range order), and on the (2 x 4)-c(2 x 8) GaAs surface (short range order). These results are discussed in terms of interface bonding between molecules and the substrate. The second part deals with the electronic and chemical structure of PTCDA thin films and the band lineup of the PTCDA/GaAs heterojunction investigated by Ultraviolet - and X-ray Photoemission Spectroscopies. A basic understanding of the valence band structure and chemical states is obtained with the help of a semi-empirical molecular orbital calculation. At the PTCDA/GaAs interface, the PTCDA highest occupied molecular orbital is found to be ~0.7 eV below the GaAs valence band maximum. This result is discussed in light of previous electrical measurements. Third, chemistry of metal deposition on PTCDA is investigated by synchrotron radiation photoemission spectroscopy. Al, Ti, In, and Sn are found to be highly reactive against PTCDA, yielding a considerable interfacial layer with a large density of states in the PTCDA gap. Ag and Au are found to be inert against PTCDA, producing abrupt interfaces. These results are found to be directly correlated with the electrical properties. Finally, chemistry of contacts formed by reversing the sequence of deposition, i.e. PTCDA on reactive metals (In, Sn, and Ti) is explored. The interfacial layers are found to be considerably smaller than for metals on PTCDA, in accordance with the

Evaluation of space environmental effects on metals and optical thin films on EOIM-3

NASA Technical Reports Server (NTRS)

Vaughn, Jason A.; Linton, Roger C.; Finckenor, Miria M.; Kamenetzky, Rachel R.

1995-01-01

Metals and optical thin films exposed to the space environment on the Third Flight of the Evaluation of Oxygen Interactions with Materials (EOIM-3) payload, onboard Space Shuttle mission STS-46 were evaluated. The materials effects described in this paper include the effects of space exposure on various pure metals, optical thin films, and optical thin film metals. The changes induced by exposure to the space environment in the material properties were evaluated using bidirectional reflectance distribution function (BRDF), specular reflectance (250 nm to 2500 nm), ESCA, VUV reflectance (120 nm to 200 nm), ellipsometry, FTIR and optical properties. Using these analysis techniques gold optically thin film metal mirrors with nickel undercoats were observed to darken due to nickel diffusion through the gold to the surface. Also, thin film nickel mirrors formed nickel oxide due to exposure to both the atmosphere and space.

Confining metal-halide perovskites in nanoporous thin films

PubMed Central

Demchyshyn, Stepan; Roemer, Janina Melanie; Groiß, Heiko; Heilbrunner, Herwig; Ulbricht, Christoph; Apaydin, Dogukan; Böhm, Anton; Rütt, Uta; Bertram, Florian; Hesser, Günter; Scharber, Markus Clark; Sariciftci, Niyazi Serdar; Nickel, Bert; Bauer, Siegfried; Głowacki, Eric Daniel; Kaltenbrunner, Martin

2017-01-01

Controlling the size and shape of semiconducting nanocrystals advances nanoelectronics and photonics. Quantum-confined, inexpensive, solution-derived metal halide perovskites offer narrowband, color-pure emitters as integral parts of next-generation displays and optoelectronic devices. We use nanoporous silicon and alumina thin films as templates for the growth of perovskite nanocrystallites directly within device-relevant architectures without the use of colloidal stabilization. We find significantly blue-shifted photoluminescence emission by reducing the pore size; normally infrared-emitting materials become visibly red, and green-emitting materials become cyan and blue. Confining perovskite nanocrystals within porous oxide thin films drastically increases photoluminescence stability because the templates auspiciously serve as encapsulation. We quantify the template-induced size of the perovskite crystals in nanoporous silicon with microfocus high-energy x-ray depth profiling in transmission geometry, verifying the growth of perovskite nanocrystals throughout the entire thickness of the nanoporous films. Low-voltage electroluminescent diodes with narrow, blue-shifted emission fabricated from nanocrystalline perovskites grown in embedded nanoporous alumina thin films substantiate our general concept for next-generation photonic devices. PMID:28798959

Magnetoelastic Properties of Magnetic Thin Films Using the Magnetooptic Kerr Effect

NASA Astrophysics Data System (ADS)

Mayo, Elizabeth; Lederman, David

1998-03-01

The magnetoelastic properties of Co and Fe thin films were measured using the magnetooptic Kerr effect (MOKE). Films were grown via magnetron sputtering on thin mica substrates. Magnetization loops were measured using MOKE with the magnetic field along different in-plane directions. Subsequently, the samples were mounted on a cylindrical sample holder, which imposed a well-defined strain to the film. This caused the magnetization loops to change dramatically due to the magnetoelastic coefficient of the thin film materials. The effects of the surface roughness and film thickness will also be discussed.

Patterning layer-by-layer self-assembled multilayer by lithography and its applications to thin film devices

NASA Astrophysics Data System (ADS)

Hua, Feng

Nanoparticles are exciting materials because they exhibit unique electronic, catalytic, and optical properties. As a novel and promising nanobuilding block, it attracts considerable research efforts in its integration into a wide variety of thin film devices. Nanoparticles were adsorbed onto the substrate with layer-by-layer self-assembly which becomes of great interest due to its suitability in colloid particle assembly. Without extremely high temperatures and sophisticated equipment, molecularly organized films in an exactly pre-designed order can grow on almost all the substrates in nature. Two approaches generating spatially separated patterns comprised of nanoparticles are demonstrated, as well as two approaches patterning more than one type of nonoparticle on a silicon wafer. The structure of the thin film patterned by these approaches are analyzed and considered suitable to the thin film device. Finally, the combination of lithography and layer-by-layer (lbl) self-assembly is utilized to realize the microelectronic device with functional nonoparticles. The lbl self-assembly is the way to coat the nonoparticles and the lighography to pattern them. Based on the coating and patterning technique, a MOS-capacitor, a MOS field-effect-transistor and magnetic thin film cantilever are fabricated.

Sample-morphology effects on x-ray photoelectron peak intensities. II. Estimation of detection limits for thin-film materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, Cedric J., E-mail: cedric.powell@nist.gov; Werner, Wolfgang S. M.; Smekal, Werner

2014-09-01

The authors show that the National Institute of Standards and Technology database for the simulation of electron spectra for surface analysis (SESSA) can be used to determine detection limits for thin-film materials such as a thin film on a substrate or buried at varying depths in another material for common x-ray photoelectron spectroscopy (XPS) measurement conditions. Illustrative simulations were made for a W film on or in a Ru matrix and for a Ru film on or in a W matrix. In the former case, the thickness of a W film at a given depth in the Ru matrix wasmore » varied so that the intensity of the W 4d{sub 5/2} peak was essentially the same as that for a homogeneous RuW{sub 0.001} alloy. Similarly, the thickness of a Ru film at a selected depth in the W matrix was varied so that the intensity of the Ru 3p{sub 3/2} peak matched that from a homogeneous WRu{sub 0.01} alloy. These film thicknesses correspond to the detection limits of each minor component for measurement conditions where the detection limits for a homogeneous sample varied between 0.1 at. % (for the RuW{sub 0.001} alloy) and 1 at. % (for the WRu{sub 0.01} alloy). SESSA can be similarly used to convert estimates of XPS detection limits for a minor species in a homogeneous solid to the corresponding XPS detection limits for that species as a thin film on or buried in the chosen solid.« less

Thin-Film Phase Plates for Transmission Electron Microscopy Fabricated from Metallic Glasses.

PubMed

Dries, Manuel; Hettler, Simon; Schulze, Tina; Send, Winfried; Müller, Erich; Schneider, Reinhard; Gerthsen, Dagmar; Luo, Yuansu; Samwer, Konrad

2016-10-01

Thin-film phase plates (PPs) have become an interesting tool to enhance the contrast of weak-phase objects in transmission electron microscopy (TEM). The thin film usually consists of amorphous carbon, which suffers from quick degeneration under the intense electron-beam illumination. Recent investigations have focused on the search for alternative materials with an improved material stability. This work presents thin-film PPs fabricated from metallic glass alloys, which are characterized by a high electrical conductivity and an amorphous structure. Thin films of the zirconium-based alloy Zr65.0Al7.5Cu27.5 (ZAC) were fabricated and their phase-shifting properties were evaluated. The ZAC film was investigated by different TEM techniques, which reveal beneficial properties compared with amorphous carbon PPs. Particularly favorable is the small probability for inelastic plasmon scattering, which results from the combined effect of a moderate inelastic mean free path and a reduced film thickness due to a high mean inner potential. Small probability plasmon scattering improves contrast transfer at high spatial frequencies, which makes the ZAC alloy a promising material for PP fabrication.

Exchange Stiffness in Thin-Film Cobalt Alloys

NASA Astrophysics Data System (ADS)

Eyrich, Charles

The exchange stiffness, Aex, is one of the key parameters controlling magnetization reversal in magnetic materials but is very difficult to measure, especially in thin films. We developed a new technique for measuring the exchange stiffness of a magnetic material based on the formation of a spin spiral within two antiferromagnetically coupled ferromagnetic films [1]. Using this method, I was able to measure the exchange stiffness of thin film Co alloyed with Cr, Fe, Ni, Pd, Pt and Ru. The results of this work showed that the rate at which a substituent element reduces the exchange stiffness is not directly related to its effect on the magnetization of the alloy. These measured trends have been understood by combining measurements of element specific magnetic moments obtained using X-ray magnetic circular dichroism (XMCD) and material specific modeling based on density functional theory (DFT) within the local density approximation (LDA). The experimental results also hint at significant reduction of the exchange stiffness at the interface that can account for the difference between our results and those obtained on bulk materials.

Geometric shape control of thin film ferroelectrics and resulting structures

DOEpatents

McKee, Rodney A.; Walker, Frederick J.

2000-01-01

A monolithic crystalline structure and a method of making involves a semiconductor substrate, such as silicon, and a ferroelectric film, such as BaTiO.sub.3, overlying the surface of the substrate wherein the atomic layers of the ferroelectric film directly overlie the surface of the substrate. By controlling the geometry of the ferroelectric thin film, either during build-up of the thin film or through appropriate treatment of the thin film adjacent the boundary thereof, the in-plane tensile strain within the ferroelectric film is relieved to the extent necessary to permit the ferroelectric film to be poled out-of-plane, thereby effecting in-plane switching of the polarization of the underlying substrate material. The method of the invention includes the steps involved in effecting a discontinuity of the mechanical restraint at the boundary of the ferroelectric film atop the semiconductor substrate by, for example, either removing material from a ferroelectric film which has already been built upon the substrate, building up a ferroelectric film upon the substrate in a mesa-shaped geometry or inducing the discontinuity at the boundary by ion beam deposition techniques.

Multilayer SnSb4-SbSe Thin Films for Phase Change Materials Possessing Ultrafast Phase Change Speed and Enhanced Stability.

PubMed

Liu, Ruirui; Zhou, Xiao; Zhai, Jiwei; Song, Jun; Wu, Pengzhi; Lai, Tianshu; Song, Sannian; Song, Zhitang

2017-08-16

A multilayer thin film, comprising two different phase change material (PCM) components alternatively deposited, provides an effective means to tune and leverage good properties of its components, promising a new route toward high-performance PCMs. The present study systematically investigated the SnSb 4 -SbSe multilayer thin film as a potential PCM, combining experiments and first-principles calculations, and demonstrated that these multilayer thin films exhibit good electrical resistivity, robust thermal stability, and superior phase change speed. In particular, the potential operating temperature for 10 years is shown to be 122.0 °C and the phase change speed reaches 5 ns in the device test. The good thermal stability of the multilayer thin film is shown to come from the formation of the Sb 2 Se 3 phase, whereas the fast phase change speed can be attributed to the formation of vacancies and a SbSe metastable phase. It is also demonstrated that the SbSe metastable phase contributes to further enhancing the electrical resistivity of the crystalline state and the thermal stability of the amorphous state, being vital to determining the properties of the multilayer SnSb 4 -SbSe thin film.

Thin film cell development workshop report

NASA Technical Reports Server (NTRS)

Woodyard, James R.

1991-01-01

The Thin Film Development Workshop provided an opportunity for those interested in space applications of thin film cells to debate several topics. The unique characteristics of thin film cells as well as a number of other issues were covered during the discussions. The potential of thin film cells, key research and development issues, manufacturing issues, radiation damage, substrates, and space qualification of thin film cells were discussed.

The state of the art of thin-film photovoltaics

NASA Astrophysics Data System (ADS)

Surek, T.

1993-10-01

Thin-film photovoltaic technologies, based on materials such as amorphous or polycrystalline silicon, copper indium diselenide, cadmium telluride, and gallium arsenide, offer the potential for significantly reducing the cost of electricity generated by photovoltaics. The significant progress in the technologies, from the laboratory to the marketplace, is reviewed. The common concerns and questions raised about thin films are addressed. Based on the progress to date and the potential of these technologies, along with continuing investments by the private sector to commercialize the technologies, one can conclude that thin-film PV will provide a competitive alternative for large-scale power generation in the future.

Surface diffusion in homoepitaxial SrTiO3 thin films

NASA Astrophysics Data System (ADS)

Woo, Chang-Su; Chu, Kanghyun; Song, Jong-Hyun; Yang, Chan-Ho; Charm Lab Team; Nano Spintronics Lab Collaboration

The development of growth techniques such as molecular beam epitaxy (MBE) and pulsed laser deposition (PLD) has facilitated growths of complex oxide thin films at the atomic level .... Systematic studies on surface diffusion process of adatoms using theoretical and experimental methods allow us to understand growth mechanism enabling atomically flat thin film surface. In this presentation, we introduce the synthesis of homoepitaxial SrTiO3 thin films using a PLD equipped with reflection of high energy electron diffraction (RHEED). We determine the surface diffusion time as a function of growth temperature and extract the activation energy of diffusion on the surface by in-situ monitoring the RHEED intensity recovery during the film deposition. From the extracted experimental results, we discuss the microscopic mechanism of the diffusion process

Nucleation of fcc Ta when heating thin films

DOE PAGES

Janish, Matthew T.; Mook, William M.; Carter, C. Barry

2014-10-25

Thin tantalum films have been studied during in-situ heating in a transmission electron microscope. Diffraction patterns from the as-deposited films were typical of amorphous materials. Crystalline grains were observed to form when the specimen was annealed in-situ at 450°C. Particular attention was addressed to the formation and growth of grains with the face-centered cubic (fcc) crystal structure. As a result, these observations are discussed in relation to prior work on the formation of fcc Ta by deformation and during thin film deposition.

Growth of Cu2ZnSnS4(CZTS) by Pulsed Laser Deposition for Thin film Photovoltaic Absorber Material

NASA Astrophysics Data System (ADS)

Nandur, Abhishek; White, Bruce

2014-03-01

CZTS (Cu2ZnSnS4) has become the subject of intense interest because it is an ideal candidate absorber material for thin-film solar cells with an optimal band gap (1.5 eV), high absorption coefficient (104 cm-1) and abundant elemental components. Pulsed Laser Deposition (PLD) provides excellent control over film composition since thin films are deposited under high vacuum with excellent stoichiometry transfer from the target. CZTS thin films were deposited using PLD from a stoichiometrically close CZTS target (Cu2.6Zn1.1Sn0.7S3.44). The effects of laser energy fluence and substrate temperature and post-deposition sulfur annealing on the surface morphology, composition and optical absorption have been investigated. Optimal CZTS thin films exhibited a band gap of 1.54 eV with an absorption coefficient of 4x104cm-1. A solar cell utilizing PLD grown CZTS with the structure SLG/Mo/CZTS/CdS/ZnO/ITO showed a conversion efficiency of 5.85% with Voc = 376 mV, Jsc = 38.9 mA/cm2 and Fill Factor, FF = 0.40.

Effect of substrate baking temperature on zinc sulfide and germanium thin films optical parameters

NASA Astrophysics Data System (ADS)

Liu, Fang; Gao, Jiaobo; Yang, Chongmin; Zhang, Jianfu; Liu, Yongqiang; Liu, Qinglong; Wang, Songlin; Mi, Gaoyuan; Wang, Huina

2016-10-01

ZnS and Ge are very normal optical thin film materials in Infrared wave. Studying the influence of different substrate baking temperature to refractive index and actual deposition rates is very important to promote optical thin film quality. In the same vacuum level, monitoring thickness and evaporation rate, we use hot evaporation to deposit ZnS thin film materials and use ion-assisted electron beam to deposit Ge thin film materials with different baking temperature. We measure the spectral transmittance with the spectrophotometer and calculate the actual deposition rates and the refractive index in different temperature. With the higher and higher temperature in a particular range, ZnS and Ge refractive index become higher and actual deposition rates become smaller. The refractive index of Ge film material change with baking temperature is more sensitive than ZnS. However, ZnS film actual deposition rates change with baking temperature is more sensitive than Ge.

Mixed Valence Perovskite Cs2 Au2 I6 : A Potential Material for Thin-Film Pb-Free Photovoltaic Cells with Ultrahigh Efficiency.

PubMed

Debbichi, Lamjed; Lee, Songju; Cho, Hyunyoung; Rappe, Andrew M; Hong, Ki-Ha; Jang, Min Seok; Kim, Hyungjun

2018-03-01

New light is shed on the previously known perovskite material, Cs 2 Au 2 I 6 , as a potential active material for high-efficiency thin-film Pb-free photovoltaic cells. First-principles calculations demonstrate that Cs 2 Au 2 I 6 has an optimal band gap that is close to the Shockley-Queisser value. The band gap size is governed by intermediate band formation. Charge disproportionation on Au makes Cs 2 Au 2 I 6 a double-perovskite material, although it is stoichiometrically a single perovskite. In contrast to most previously discussed double perovskites, Cs 2 Au 2 I 6 has a direct-band-gap feature, and optical simulation predicts that a very thin layer of active material is sufficient to achieve a high photoconversion efficiency using a polycrystalline film layer. The already confirmed synthesizability of this material, coupled with the state-of-the-art multiscale simulations connecting from the material to the device, strongly suggests that Cs 2 Au 2 I 6 will serve as the active material in highly efficient, nontoxic, and thin-film perovskite solar cells in the very near future. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Universal Method for Creating Hierarchical Wrinkles on Thin-Film Surfaces.

PubMed

Jung, Woo-Bin; Cho, Kyeong Min; Lee, Won-Kyu; Odom, Teri W; Jung, Hee-Tae

2018-01-10

One of the most interesting topics in physical science and materials science is the creation of complex wrinkled structures on thin-film surfaces because of their several advantages of high surface area, localized strain, and stress tolerance. In this study, a significant step was taken toward solving limitations imposed by the fabrication of previous artificial wrinkles. A universal method for preparing hierarchical three-dimensional wrinkle structures of thin films on a multiple scale (e.g., nanometers to micrometers) by sequential wrinkling with different skin layers was developed. Notably, this method was not limited to specific materials, and it was applicable to fabricating hierarchical wrinkles on all of the thin-film surfaces tested thus far, including those of metals, two-dimensional and one-dimensional materials, and polymers. The hierarchical wrinkles with multiscale structures were prepared by sequential wrinkling, in which a sacrificial layer was used as the additional skin layer between sequences. For example, a hierarchical MoS 2 wrinkle exhibited highly enhanced catalytic behavior because of the superaerophobicity and effective surface area, which are related to topological effects. As the developed method can be adopted to a majority of thin films, it is thought to be a universal method for enhancing the physical properties of various materials.

Thermoelectric effects of amorphous Ga-Sn-O thin film

NASA Astrophysics Data System (ADS)

Matsuda, Tokiyoshi; Uenuma, Mutsunori; Kimura, Mutsumi

2017-07-01

The thermoelectric effects of an amorphous Ga-Sn-O (a-GTO) thin film have been evaluated as a physical parameter of a novel oxide semiconductor. Currently, a-GTO thin films are greatly desired not only because they do not contain rare metals and are therefore free from problems on the exhaustion of resources and the increase in cost but also because their initial characteristics and performance stabilities are excellent when they are used in thin-film transistors. In this study, an a-GTO thin film was deposited on a quartz substrate by RF magnetron sputtering and postannealing was performed in air at 350 °C for 1 h using an annealing furnace. The Seebeck coefficient and electrical conductivity of the a-GTO thin film were -137 µV/K and 31.8 S/cm at room temperature, and -183 µV/K and 43.8 S/cm at 397 K, respectively, and as a result, the power factor was 1.47 µW/(cm·K2) at 397 K; these values were roughly as high as those of amorphous In-Ga-Zn-O (a-IGZO) thin films. Therefore, a-GTO thin films will be a candidate material for thermoelectric devices fabricated in a large area at a low cost by controlling the carrier mobility, carrier density, device structures, and so forth.

Thin film metrology and microwave loss characterization of indium and aluminum/indium superconducting planar resonators

NASA Astrophysics Data System (ADS)

McRae, C. R. H.; Béjanin, J. H.; Earnest, C. T.; McConkey, T. G.; Rinehart, J. R.; Deimert, C.; Thomas, J. P.; Wasilewski, Z. R.; Mariantoni, M.

2018-05-01

Scalable architectures characterized by quantum bits (qubits) with low error rates are essential to the development of a practical quantum computer. In the superconducting quantum computing implementation, understanding and minimizing material losses are crucial to the improvement of qubit performance. A new material that has recently received particular attention is indium, a low-temperature superconductor that can be used to bond pairs of chips containing standard aluminum-based qubit circuitry. In this work, we characterize microwave loss in indium and aluminum/indium thin films on silicon substrates by measuring superconducting coplanar waveguide resonators and estimating the main loss parameters at powers down to the sub-photon regime and at temperatures between 10 and 450 mK. We compare films deposited by thermal evaporation, sputtering, and molecular beam epitaxy. We study the effects of heating in a vacuum and ambient atmospheric pressure as well as the effects of pre-deposition wafer cleaning using hydrofluoric acid. The microwave measurements are supported by thin film metrology including secondary-ion mass spectrometry. For thermally evaporated and sputtered films, we find that two-level state are the dominant loss mechanism at low photon number and temperature, with a loss tangent due to native indium oxide of ˜ 5 × 10 - 5 . The molecular beam epitaxial films show evidence of the formation of a substantial indium-silicon eutectic layer, which leads to a drastic degradation in resonator performance.

Thin film production method and apparatus

DOEpatents

Loutfy, Raouf O.; Moravsky, Alexander P.; Hassen, Charles N.

2010-08-10

A method for forming a thin film material which comprises depositing solid particles from a flowing suspension or aerosol onto a filter and next adhering the solid particles to a second substrate using an adhesive.

Effect of current injection into thin-film Josephson junctions

DOE PAGES

Kogan, V. G.; Mints, R. G.

2014-11-11

New thin-film Josephson junctions have recently been tested in which the current injected into one of the junction banks governs Josephson phenomena. One thus can continuously manage the phase distribution at the junction by changing the injected current. Our method of calculating the distribution of injected currents is also proposed for a half-infinite thin-film strip with source-sink points at arbitrary positions at the film edges. The strip width W is assumed small relative to Λ=2λ 2/d;λ is the bulk London penetration depth of the film material and d is the film thickness.

Strategies towards controlling strain-induced mesoscopic phase separation in manganite thin films

NASA Astrophysics Data System (ADS)

Habermeier, H.-U.

2008-10-01

Complex oxides represent a class of materials with a plethora of fascinating intrinsic physical functionalities. The intriguing interplay of charge, spin and orbital ordering in these systems superimposed by lattice effects opens a scientifically rewarding playground for both fundamental as well as application oriented research. The existence of nanoscale electronic phase separation in correlated complex oxides is one of the areas in this field whose impact on the current understanding of their physics and potential applications is not yet clear. In this paper this issue is treated from the point of view of complex oxide thin film technology. Commenting on aspects of complex oxide thin film growth gives an insight into the complexity of a reliable thin film technology for these materials. Exploring fundamentals of interfacial strain generation and strain accommodation paves the way to intentionally manipulate thin film properties. Furthermore, examples are given for an extrinsic continuous tuning of intrinsic electronic inhomogeneities in perovskite-type complex oxide thin films.

Emittance Theory for Thin Film Selective Emitter

NASA Technical Reports Server (NTRS)

Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

1994-01-01

Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

NASA Astrophysics Data System (ADS)

Ievlev, Anton V.; Chyasnavichyus, Marius; Leonard, Donovan N.; Agar, Joshua C.; Velarde, Gabriel A.; Martin, Lane W.; Kalinin, Sergei V.; Maksymovych, Petro; Ovchinnikova, Olga S.

2018-04-01

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ievlev, Anton; Chyasnavichyus, Marius; Leonard, Donovan N.

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy tomore » a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Lastly, our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.« less

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

DOE PAGES

Ievlev, Anton; Chyasnavichyus, Marius; Leonard, Donovan N.; ...

2018-02-22

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy tomore » a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Lastly, our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.« less

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness.

PubMed

Ievlev, Anton V; Chyasnavichyus, Marius; Leonard, Donovan N; Agar, Joshua C; Velarde, Gabriel A; Martin, Lane W; Kalinin, Sergei V; Maksymovych, Petro; Ovchinnikova, Olga S

2018-04-02

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

Rechargeable Thin-film Lithium Batteries

DOE R&D Accomplishments Database

Bates, J. B.; Gruzalski, G. R.; Dudney, N. J.; Luck, C. F.; Yu, Xiaohua

1993-08-01

Rechargeable thin film batteries consisting of lithium metal anodes, an amorphous inorganic electrolyte, and cathodes of lithium intercalation compounds have recently been developed. The batteries, which are typically less than 6 {mu}m thick, can be fabricated to any specified size, large or small, onto a variety of substrates including ceramics, semiconductors, and plastics. The cells that have been investigated include Li TiS{sub 2}, Li V{sub 2}O{sub 5}, and Li Li{sub x}Mn{sub 2}O{sub 4}, with open circuit voltages at full charge of about 2.5, 3.6, and 4.2, respectively. The development of these batteries would not have been possible without the discovery of a new thin film lithium electrolyte, lithium phosphorus oxynitride, that is stable in contact with metallic lithium at these potentials. Deposited by rf magnetron sputtering of Li{sub 3}PO{sub 4} in N{sub 2}, this material has a typical composition of Li{sub 2.9}PO{sub 3.3}N{sub 0.46} and a conductivity at 25{degrees}C of 2 {mu}S/cm. The maximum practical current density obtained from the thin film cells is limited to about 100 {mu}A/cm{sup 2} due to a low diffusivity of Li{sup +} ions in the cathodes. In this work, the authors present a short review of their work on rechargeable thin film lithium batteries.

Optical, wetting and electrical properties of functionalized fulleropyrrolidine thin films

NASA Astrophysics Data System (ADS)

Abdulrazack, Parveen; Venkatesan, Sughanya; Chellasamy, Manoharan; Samuthira, Nagarajan

2017-12-01

Fulleropyrrolidine derivatives acts as an electron acceptor in the fabrication of solar cells and other optoelectronic devices. In this investigation thin film of functionalized fulleropyrrolidines were fabricated and studied their photo-physical properties. Surface morphology of the thin films was investigated through AFM and FE-SEM. The results suggested that large dependence on structure vs molecular packing. The long alkyl chain substituted C60 were assembled in the form of nanorods. C60- C60 intermolecular distance were measured, the films were with good absorption and exhibits n-type semiconducting behavior. The films were having high contact angle and can be effectively used for fabricating semiconducting devices with self- cleaning property.

Controlling the Pore Size of Mesoporous Carbon Thin Films through Thermal and Solvent Annealing.

PubMed

Zhou, Zhengping; Liu, Guoliang

2017-04-01

Herein an approach to controlling the pore size of mesoporous carbon thin films from metal-free polyacrylonitrile-containing block copolymers is described. A high-molecular-weight poly(acrylonitrile-block-methyl methacrylate) (PAN-b-PMMA) is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The authors systematically investigate the self-assembly behavior of PAN-b-PMMA thin films during thermal and solvent annealing, as well as the pore size of mesoporous carbon thin films after pyrolysis. The as-spin-coated PAN-b-PMMA is microphase-separated into uniformly spaced globular nanostructures, and these globular nanostructures evolve into various morphologies after thermal or solvent annealing. Surprisingly, through thermal annealing and subsequent pyrolysis of PAN-b-PMMA into mesoporous carbon thin films, the pore size and center-to-center spacing increase significantly with thermal annealing temperature, different from most block copolymers. In addition, the choice of solvent in solvent annealing strongly influences the block copolymer nanostructure and the pore size of mesoporous carbon thin films. The discoveries herein provide a simple strategy to control the pore size of mesoporous carbon thin films by tuning thermal or solvent annealing conditions, instead of synthesizing a series of block copolymers of various molecular weights and compositions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A-site- and/or B-site-modified PbZrTiO3 materials and (Pb, Sr, Ca, Ba, Mg) (Zr, Ti, Nb, Ta)O3 films having utility in ferroelectric random access memories and high performance thin film microactuators

NASA Technical Reports Server (NTRS)

Bilodeau, Steven (Inventor); Baum, Thomas H. (Inventor); Roeder, Jeffrey F. (Inventor); Chen, Ing-Shin (Inventor)

2001-01-01

A modified PbZrTiO.sub.3 perovskite crystal material thin film, wherein the PbZrTiO.sub.3 perovskite crystal material includes crystal lattice A-sites and B-sites at least one of which is modified by the presence of a substituent selected from the group consisting of (i) A-site substituents consisting of Sr, Ca, Ba and Mg, and (ii) B-site substituents selected from the group consisting of Nb and Ta. The perovskite crystal thin film material may be formed by liquid delivery MOCVD from metalorganic precursors of the metal components of the thin film, to form PZT and PSZT, and other piezoelectric and ferroelectric thin film materials. The thin films of the invention have utility in non-volatile ferroelectric memory devices (NV-FeRAMs), and in microelectromechanical systems (MEMS) as sensor and/or actuator elements, e.g., high speed digital system actuators requiring low input power levels.

Thin-film semiconductor perspective of organometal trihalide perovskite materials for high-efficiency solar cells

DOE PAGES

Xiao, Zhengguo; Yuan, Yongbo; Wang, Qi; ...

2016-02-19

Organolead trihalide perovskites (OTPs) are arising as a new generation of low-cost active materials for solar cells with efficiency rocketing from 3.5% to over 20% within only five years. From “dye” in dye sensitized solar cells to “hole conductors” and “electron conductors” in mesoscopic heterojunction solar cells, there has been a dramatic conceptual evolution on the function of OTPs in photovoltaic devices. OTPs were originally used as dyes in Gratzel cells, achieving a high efficiency above 15% which, however, did not manifest the excellent charge transport properties of OTPs. An analogy of OTPs to traditional semiconductors was drawn after themore » demonstration of highly efficient planar heterojunction structure OTP devices and the observation of their excellent bipolar transport properties with a large diffusion length exceeding 100 nm in CH 3NH 3PbI 3 (MAPbI 3) polycrystalline thin films. Here, this review aims to provide the most recent advances in the understanding of the origin of the high OTP device efficiency. Specifically we will focus on reviewing the progress in understanding 1) the characterization of fantastic optoelectronic property of OTPs, 2) the unusual defect physics that originate the optoelectronic property; 3) morphology control of the perovskite film from fabrication process and film post-treatment, and 4) device interface and charge transport layers that dramatically impact device efficiency in the OTP thin film devices; 5) photocurrent hysteresis; 6) tandem solar cells; 7) stability of the perovskite materials and solar cell devices.« less

Boundary element method for 2D materials and thin films.

PubMed

Hrtoň, M; Křápek, V; Šikola, T

2017-10-02

2D materials emerge as a viable platform for the control of light at the nanoscale. In this context the need has arisen for a fast and reliable tool capable of capturing their strictly 2D nature in 3D light scattering simulations. So far, 2D materials and their patterned structures (ribbons, discs, etc.) have been mostly treated as very thin films of subnanometer thickness with an effective dielectric function derived from their 2D optical conductivity. In this study an extension to the existing framework of the boundary element method (BEM) with 2D materials treated as a conductive interface between two media is presented. The testing of our enhanced method on problems with known analytical solutions reveals that for certain types of tasks the new modification is faster than the original BEM algorithm. Furthermore, the representation of 2D materials as an interface allows us to simulate problems in which their optical properties depend on spatial coordinates. Such spatial dependence can occur naturally or can be tailored artificially to attain new functional properties.

Nanocomposite thin films for triggerable drug delivery.

PubMed

Vannozzi, Lorenzo; Iacovacci, Veronica; Menciassi, Arianna; Ricotti, Leonardo

2018-05-01

Traditional drug release systems normally rely on a passive delivery of therapeutic compounds, which can be partially programmed, prior to injection or implantation, through variations in the material composition. With this strategy, the drug release kinetics cannot be remotely modified and thus adapted to changing therapeutic needs. To overcome this issue, drug delivery systems able to respond to external stimuli are highly desirable, as they allow a high level of temporal and spatial control over drug release kinetics, in an operator-dependent fashion. Areas covered: On-demand drug delivery systems actually represent a frontier in this field and are attracting an increasing interest at both research and industrial level. Stimuli-responsive thin films, enabled by nanofillers, hold a tremendous potential in the field of triggerable drug delivery systems. The inclusion of responsive elements in homogeneous or heterogeneous thin film-shaped polymeric matrices strengthens and/or adds intriguing properties to conventional (bare) materials in film shape. Expert opinion: This Expert Opinion review aims to discuss the approaches currently pursued to achieve an effective on-demand drug delivery, through nanocomposite thin films. Different triggering mechanisms allowing a fine control on drug delivery are described, together with current challenges and possible future applications in therapy and surgery.

Ultra-smooth glassy graphene thin films for flexible transparent circuits

PubMed Central

Dai, Xiao; Wu, Jiang; Qian, Zhicheng; Wang, Haiyan; Jian, Jie; Cao, Yingjie; Rummeli, Mark H.; Yi, Qinghua; Liu, Huiyun; Zou, Guifu

2016-01-01

Large-area graphene thin films are prized in flexible and transparent devices. We report on a type of glassy graphene that is in an intermediate state between glassy carbon and graphene and that has high crystallinity but curly lattice planes. A polymer-assisted approach is introduced to grow an ultra-smooth (roughness, <0.7 nm) glassy graphene thin film at the inch scale. Owing to the advantages inherited by the glassy graphene thin film from graphene and glassy carbon, the glassy graphene thin film exhibits conductivity, transparency, and flexibility comparable to those of graphene, as well as glassy carbon–like mechanical and chemical stability. Moreover, glassy graphene–based circuits are fabricated using a laser direct writing approach. The circuits are transferred to flexible substrates and are shown to perform reliably. The glassy graphene thin film should stimulate the application of flexible transparent conductive materials in integrated circuits. PMID:28138535

Low work function, stable thin films

DOEpatents

Dinh, Long N.; McLean, II, William; Balooch, Mehdi; Fehring, Jr., Edward J.; Schildbach, Marcus A.

2000-01-01

Generation of low work function, stable compound thin films by laser ablation. Compound thin films with low work function can be synthesized by simultaneously laser ablating silicon, for example, and thermal evaporating an alkali metal into an oxygen environment. For example, the compound thin film may be composed of Si/Cs/O. The work functions of the thin films can be varied by changing the silicon/alkali metal/oxygen ratio. Low work functions of the compound thin films deposited on silicon substrates were confirmed by ultraviolet photoelectron spectroscopy (UPS). The compound thin films are stable up to 500.degree. C. as measured by x-ray photoelectron spectroscopy (XPS). Tests have established that for certain chemical compositions and annealing temperatures of the compound thin films, negative electron affinity (NEA) was detected. The low work function, stable compound thin films can be utilized in solar cells, field emission flat panel displays, electron guns, and cold cathode electron guns.

Quantifying resistances across nanoscale low- and high-angle interspherulite boundaries in solution-processed organic semiconductor thin films.

PubMed

Lee, Stephanie S; Mativetsky, Jeffrey M; Loth, Marsha A; Anthony, John E; Loo, Yueh-Lin

2012-11-27

The nanoscale boundaries formed when neighboring spherulites impinge in polycrystalline, solution-processed organic semiconductor thin films act as bottlenecks to charge transport, significantly reducing organic thin-film transistor mobility in devices comprising spherulitic thin films as the active layers. These interspherulite boundaries (ISBs) are structurally complex, with varying angles of molecular orientation mismatch along their lengths. We have successfully engineered exclusively low- and exclusively high-angle ISBs to elucidate how the angle of molecular orientation mismatch at ISBs affects their resistivities in triethylsilylethynyl anthradithiophene thin films. Conductive AFM and four-probe measurements reveal that current flow is unaffected by the presence of low-angle ISBs, whereas current flow is significantly disrupted across high-angle ISBs. In the latter case, we estimate the resistivity to be 22 MΩμm(2)/width of the ISB, only less than a quarter of the resistivity measured across low-angle grain boundaries in thermally evaporated sexithiophene thin films. This discrepancy in resistivities across ISBs in solution-processed organic semiconductor thin films and grain boundaries in thermally evaporated organic semiconductor thin films likely arises from inherent differences in the nature of film formation in the respective systems.

Mechanics of fragmentation of crocodile skin and other thin films.

PubMed

Qin, Zhao; Pugno, Nicola M; Buehler, Markus J

2014-05-27

Fragmentation of thin layers of materials is mediated by a network of cracks on its surface. It is commonly seen in dehydrated paintings or asphalt pavements and even in graphene or other two-dimensional materials, but is also observed in the characteristic polygonal pattern on a crocodile's head. Here, we build a simple mechanical model of a thin film and investigate the generation and development of fragmentation patterns as the material is exposed to various modes of deformation. We find that the characteristic size of fragmentation, defined by the mean diameter of polygons, is strictly governed by mechanical properties of the film material. Our result demonstrates that skin fragmentation on the head of crocodiles is dominated by that it features a small ratio between the fracture energy and Young's modulus, and the patterns agree well with experimental observations. Understanding this mechanics-driven process could be applied to improve the lifetime and reliability of thin film coatings by mimicking crocodile skin.

Mechanics of fragmentation of crocodile skin and other thin films

PubMed Central

Qin, Zhao; Pugno, Nicola M.; Buehler, Markus J.

2014-01-01

Fragmentation of thin layers of materials is mediated by a network of cracks on its surface. It is commonly seen in dehydrated paintings or asphalt pavements and even in graphene or other two-dimensional materials, but is also observed in the characteristic polygonal pattern on a crocodile's head. Here, we build a simple mechanical model of a thin film and investigate the generation and development of fragmentation patterns as the material is exposed to various modes of deformation. We find that the characteristic size of fragmentation, defined by the mean diameter of polygons, is strictly governed by mechanical properties of the film material. Our result demonstrates that skin fragmentation on the head of crocodiles is dominated by that it features a small ratio between the fracture energy and Young's modulus, and the patterns agree well with experimental observations. Understanding this mechanics-driven process could be applied to improve the lifetime and reliability of thin film coatings by mimicking crocodile skin. PMID:24862190

Mechanics of fragmentation of crocodile skin and other thin films

NASA Astrophysics Data System (ADS)

Qin, Zhao; Pugno, Nicola M.; Buehler, Markus J.

2014-05-01

Fragmentation of thin layers of materials is mediated by a network of cracks on its surface. It is commonly seen in dehydrated paintings or asphalt pavements and even in graphene or other two-dimensional materials, but is also observed in the characteristic polygonal pattern on a crocodile's head. Here, we build a simple mechanical model of a thin film and investigate the generation and development of fragmentation patterns as the material is exposed to various modes of deformation. We find that the characteristic size of fragmentation, defined by the mean diameter of polygons, is strictly governed by mechanical properties of the film material. Our result demonstrates that skin fragmentation on the head of crocodiles is dominated by that it features a small ratio between the fracture energy and Young's modulus, and the patterns agree well with experimental observations. Understanding this mechanics-driven process could be applied to improve the lifetime and reliability of thin film coatings by mimicking crocodile skin.

Packaging material for thin film lithium batteries

DOEpatents

Bates, John B.; Dudney, Nancy J.; Weatherspoon, Kim A.

1996-01-01

A thin film battery including components which are capable of reacting upon exposure to air and water vapor incorporates a packaging system which provides a barrier against the penetration of air and water vapor. The packaging system includes a protective sheath overlying and coating the battery components and can be comprised of an overlayer including metal, ceramic, a ceramic-metal combination, a parylene-metal combination, a parylene-ceramic combination or a parylene-metal-ceramic combination.

Drop dynamics on a thin film: Thin film rupture

NASA Astrophysics Data System (ADS)

Carlson, Andreas; Kim, Pilnam; Stone, Howard A.

2011-11-01

The spreading of a water drop on an oil film that covers a solid substrate is a common event in many industrial processes. We study in experiments the dynamics of a water drop on a thin silicone oil film and quantify its interaction with the solid substrate that supports the film. The oil film becomes unstable and ruptures for solids that are hydrophilic. We determine the ``waiting time,'' the time it takes the water drop to drain the silicone film. This timescale is found to highly depend on how well water wets the solid, illustrating the interplay between intermolecular and hydrodynamic forces in the phenomenon. A phase diagram for the thin film stability is extracted based on waters equilibrium contact angle on the solid, which shows that we can either promote or inhibit de-wetting. As water comes in direct contact with the solid, it spreads and peels off the silicone film. We show the influence of viscosity, equilibrium contact angle and film height on the opening radius of the hole formed as the solid de-wets.

Tungsten-rhenium thin film thermocouples for SiC-based ceramic matrix composites

NASA Astrophysics Data System (ADS)

Tian, Bian; Zhang, Zhongkai; Shi, Peng; Zheng, Chen; Yu, Qiuyue; Jing, Weixuan; Jiang, Zhuangde

2017-01-01

A tungsten-rhenium thin film thermocouple is designed and fabricated, depending on the principle of thermal-electric effect caused by the high temperature. The characteristics of thin film thermocouples in different temperatures are investigated via numerical analysis and analog simulation. The working mechanism and thermo-electric features of the thermocouples are analyzed depending on the simulation results. Then the thin film thermocouples are fabricated and calibrated. The calibration results show that the thin film thermocouples based on the tungsten-rhenium material achieve ideal static characteristics and work well in the practical applications.