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Sample records for chemical bath deposited

  1. Chemical bath deposition of II-VI compound thin films

    NASA Astrophysics Data System (ADS)

    Oladeji, Isaiah Olatunde

    II-VI compounds are direct bandgap semiconductors with great potentials in optoelectronic applications. Solar cells, where these materials are in greater demand, require a low cost production technology that will make the final product more affordable. Chemical bath deposition (CBD) a low cost growth technique capable of producing good quality thin film semiconductors over large area and at low temperature then becomes a suitable technology of choice. Heterogeneous reaction in a basic aqueous solution that is responsible for the II-VI compound film growth in CBD requires a metal complex. We have identified the stability constant (k) of the metal complex compatible with CBD growth mechanism to be about 106.9. This value is low enough to ensure that the substrate adsorbed complex relax for subsequent reaction with the chalcogen precursor to take place. It is also high enough to minimize the metal ion concentration in the bath participating in the precipitation of the bulk compounds. Homogeneous reaction that leads to precipitation in the reaction bath takes place because the solubility products of bulk II-VI compounds are very low. This reaction quickly depletes the bath of reactants, limit the film thickness, and degrade the film quality. While ZnS thin films are still hard to grow by CBD because of lack of suitable complexing agent, the homogeneous reaction still limits quality and thickness of both US and ZnS thin films. In this study, the zinc tetraammine complex ([Zn(NH3) 4]2+) with k = 108.9 has been forced to acquire its unsaturated form [Zn(NH3)3]2+ with a moderate k = 106.6 using hydrazine and nitrilotriacetate ion as complementary complexing agents and we have successfully grown ZnS thin films. We have also, minimized or eliminated the homogeneous reaction by using ammonium salt as a buffer and chemical bath with low reactant concentrations. These have allowed us to increase the saturation thickness of ZnS thin film by about 400% and raise that of US film

  2. SnS thin films deposited by chemical bath deposition, dip coating and SILAR techniques

    NASA Astrophysics Data System (ADS)

    Chaki, Sunil H.; Chaudhary, Mahesh D.; Deshpande, M. P.

    2016-05-01

    The SnS thin films were synthesized by chemical bath deposition (CBD), dip coating and successive ionic layer adsorption and reaction (SILAR) techniques. In them, the CBD thin films were deposited at two temperatures: ambient and 70 °C. The energy dispersive analysis of X-rays (EDAX), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and optical spectroscopy techniques were used to characterize the thin films. The electrical transport properties studies on the as-deposited thin films were done by measuring the I–V characteristics, DC electrical resistivity variation with temperature and the room temperature Hall effect. The obtained results are deliberated in this paper.

  3. Influence of Deposition Time on ZnS Thin Films Performance with Chemical Bath Deposition

    NASA Astrophysics Data System (ADS)

    Zhou, Limei; Tang, Nan; Wu, Sumei; Hu, Xiaofei; Xue, Yuzhi

    ZnS thin films had been deposited by chemical bath deposition method onto glass substrates in alkaline liquor. The reaction solution is made of ZnSO4, NH4OH and SC(NH2)2. Different deposition times (1 h, 1.5 h, 2 h, 2.5 h and 3 h) were selected to study the performance of ZnS thin films. As the results, the ZnS films' thickness were about 50-207 nm. XRD results showed an amorphous structure. Through comparing the surface morphology before and after annealing, it could be seen that annealing made some particles grow up and the surface smooth and even. The transmittance decreased with the increase of deposition time in the range of 300-800 nm. The transmittance of annealed ZnS film was lower than that of deposited one in the range of 300-800 nm. The ZnS band gap values were calculated in the range of 3.72-3.9 eV.

  4. Morphology control of zinc oxide films via polysaccharide-mediated, low temperature, chemical bath deposition

    PubMed Central

    Schneider, Andreas M; Eiden, Stefanie

    2015-01-01

    Summary In this study we present a three-step process for the low-temperature chemical bath deposition of crystalline ZnO films on glass substrates. The process consists of a seeding step followed by two chemical bath deposition steps. In the second step (the first of the two bath deposition steps), a natural polysaccharide, namely hyaluronic acid, is used to manipulate the morphology of the films. Previous experiments revealed a strong influence of this polysaccharide on the formation of zinc oxide crystallites. The present work aims to transfer this gained knowledge to the formation of zinc oxide films. The influence of hyaluronic acid and the time of its addition on the morphology of the resulting ZnO film were investigated. By meticulous adjustment of the parameters in this step, the film morphology can be tailored to provide an optimal growth platform for the third step (a subsequent chemical bath deposition step). In this step, the film is covered by a dense layer of ZnO. This optimized procedure leads to ZnO films with a very high electrical conductivity, opening up interesting possibilities for applications of such films. The films were characterized by means of electron microscopy, X-ray diffraction and measurements of the electrical conductivity. PMID:25977851

  5. Morphology control of zinc oxide films via polysaccharide-mediated, low temperature, chemical bath deposition.

    PubMed

    Waltz, Florian; Schwarz, Hans-Christoph; Schneider, Andreas M; Eiden, Stefanie; Behrens, Peter

    2015-01-01

    In this study we present a three-step process for the low-temperature chemical bath deposition of crystalline ZnO films on glass substrates. The process consists of a seeding step followed by two chemical bath deposition steps. In the second step (the first of the two bath deposition steps), a natural polysaccharide, namely hyaluronic acid, is used to manipulate the morphology of the films. Previous experiments revealed a strong influence of this polysaccharide on the formation of zinc oxide crystallites. The present work aims to transfer this gained knowledge to the formation of zinc oxide films. The influence of hyaluronic acid and the time of its addition on the morphology of the resulting ZnO film were investigated. By meticulous adjustment of the parameters in this step, the film morphology can be tailored to provide an optimal growth platform for the third step (a subsequent chemical bath deposition step). In this step, the film is covered by a dense layer of ZnO. This optimized procedure leads to ZnO films with a very high electrical conductivity, opening up interesting possibilities for applications of such films. The films were characterized by means of electron microscopy, X-ray diffraction and measurements of the electrical conductivity. PMID:25977851

  6. Preparation and Characterization of SnO2 thin films deposited by Chemical Bath Deposition method

    NASA Astrophysics Data System (ADS)

    Yusuf, Gbadebo; Raimi, Adepoju; Familusi, Timothy; Awodugba, Ayodeji; Efunwole, Hezekiah

    2013-04-01

    SnO2 thin films have been deposited onto the soda lime glass substrates by the chemical bath deposition method. The structural and optical properties of the SnO2 thin films were investigated. Tin chloride solution (SnCl2) and methanol were used as starting materials at substrate temperature 300°C. The crystal structure and orientation of the SnO2 thin films were investigated by X-ray diffraction (XRD) patterns. The average grain size of the films was calculated using the Scherer formula and was found to be 29.6 nm which increased to 30.04nm after annealing in air at 400°C. The optical absorbance and transmittance measurements were recorded by using spectrophotometer. The average transmittance of the film was around 80 % at wavelength 550 nm. The optical band gap of the thin films was determined and found to be 3.71eV. The gas sensing properties of tin oxide thin films obtained in this work could be performed for different gases like CO, CH4, H2S, H2 etc. The Authors would like to acknowledge the encouragement and financial support from the Management of Osun state Polytechnic, Iree.

  7. Preparation and Characterization of SnO2 thin films deposited by Chemical Bath Deposition method

    NASA Astrophysics Data System (ADS)

    Yusuf, Gbadebo T.; Raimi, Adepoju M.; Familusi, Timothy O.; Awodugba, Ayodeji O.; Efunwole, Hezekiah O.

    2013-04-01

    SnO2 thin films have been deposited onto the soda lime glass substrates by the chemical bath deposition method. The structural and optical properties of the SnO2 thin films were investigated. Tin chloride solution (SnCl2) and methanol were used as starting materials at substrate temperature 300^oC. The crystal structure and orientation of the SnO2 thin films were investigated by X-ray diffraction (XRD) patterns. The average grain size of the films was calculated using the Scherer formula and was found to be 29.6 nm which increased to 30.04nm after annealing in air at 400^oC. The optical absorbance and transmittance measurements were recorded by using spectrophotometer. The average transmittance of the film was around 80 % at wavelength 550 nm. The optical band gap of the thin films was determined and found to be 3.71eV. The gas sensing properties of tin oxide thin films obtained in this work could be performed for different gases like CO, CH4, H2S, H2 etc.

  8. Comprehensive optical studies on SnS layers synthesized by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Gedi, Sreedevi; Minnam Reddy, Vasudeva Reddy; Park, Chinho; Chan-Wook, Jeon; Ramakrishna Reddy, K. T.

    2015-04-01

    A simple non-vacuum and cost effective wet chemical technique, chemical bath deposition was used to prepare tin sulphide (SnS) layers on glass substrates. The layers were formed by varying bath temperature in the range, 40-80 °C, keeping other deposition parameters as constant. An exhaustive investigation on their optical properties with bath temperature was made using the transmittance and reflectance measurements. The absorption coefficient was evaluated from the optical transmittance data utilizing Lambert's principle and is >104 cm-1 for all the as-prepared layers. The energy band gap of the layers was determined from the differential reflectance spectra that varied from 1.41 eV to 1.30 eV. Consequently, refractive index and extinction coefficient were obtained from Pankov relations and dispersion constants were calculated using Wemple-Didomenico method. In addition, other optical parameters such as the optical conductivity, dielectric constants, dissipation factor, high frequency dielectric constant and relaxation time were also calculated. Finally electrical parameters such as resistivity, carrier mobility and carrier density of as-prepared layers were estimated using optical data. A detailed analysis of the dependence of all above mentioned parameters on bath temperature is reported and discussed for a clean understanding of electronic characteristics of SnS layers.

  9. Nanocrystalline CuInSSe thin films by chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Shrotriya, Vipin; Rajaram, P.

    2016-05-01

    Crystalline CuInSSe thin films have been deposited on glass substrate by chemical bath deposition technique. The CuCl2, InCl3, thiourea and SeO2 were used as source materials for the Cu2+, In3+, S2- and Se2- ions and the Cu/In ratio was kept at 1.0. EDC was used as a complexing agent. The XRD, Scanning Electron Microscope (SEM), Energy Dispersive Analysis of X-Ray (EDAX) and Optical transmission studies were used for structural analysis, surface morphology, elemental analysis and optical band gap, of the grown thin films respectively. The deposition parameters such as pH, deposition temperature and deposition time were optimized.

  10. Annealing effect on Cu2S thin films prepared by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    More, Pawan; Dhanayat, Swapnali; Gattu, Ketan; Mahajan, Sandeep; Upadhye, Deepak; Sharma, Ramphal

    2016-05-01

    In present work Cu2S thin film fabricated on glass substrate by simple, cost effective chemical bath deposition method subsequently it annealed at 150°c.These films were studied for their structural, optical and electrical properties using X-ray diffraction, UV-vis spectrophotometer and I-V system. The results show successful synthesis of Cu2S thin films and improvement in crystalline nature of the thin film which resulted in reduced bad gap and resistance of the film. Thus these thinfilms prove to be a promising candidate for solar cell application.

  11. Fabrication of ZnO nanorod using spray-pyrolysis and chemical bath deposition method

    SciTech Connect

    Ramadhani, Muhammad F. Pasaribu, Maruli A. H. Yuliarto, Brian Nugraha

    2014-02-24

    ZnO thin films with nanorod structure were deposited using Ultrasonic Spray Pyrolysis method for seed growth, and Chemical Bath Deposition (CBD) for nanorod growth. High purity Zn-hydrate and Urea are used to control Ph were dissolved in ethanol and aqua bidest in Ultrasonic Spray Pyrolysis process. Glass substrate was placed above the heater plate of reaction chamber, and subsequently sprayed with the range duration of 5, 10 and 20 minutes at the temperatures of 3500 C. As for the Chemical Bath Deposition, the glass substrate with ZnO seed on the surface was immerse to Zn-hydrate, HMTA (Hexa Methylene Tetra Amine) and deionized water solution for duration of 3, 5 and 7 hour and temperatures of 600 C, washed in distilled water, dried, and annealed at 3500 C for an hour. The characterization of samples was carried out to reveal the surface morphology using Scanning Electron Microscopy (SEM). From the data, the combination of 5 minutes of Ultrasonic Spray Pyrolysis process and 3 hour of CBD has showed the best structure of nanorod. Meanwhile the longer Spraying process and CBD yield the bigger nanorod structure that have been made, and it makes the films more dense which make the nanorod collide each other and as a result produce unsymetric nanorod structure.

  12. Low-temperature chemical bath deposition of crystalline ZnO

    NASA Astrophysics Data System (ADS)

    Jacobs, Klaus; Balitsky, Denis; Armand, Pascale; Papet, Philippe

    2010-03-01

    ZnO crystals can be grown from alkaline aqueous solution not only by the standard hydrothermal technique at temperatures between 350 °C and 400 °C, but also by chemical bath deposition (CBD) at temperatures below 100 °C. In the presence of ZnO and ScAlMgO 4 (SCAM) substrates almost all ZnO deposits on the substrate, with different habits, however. Under optimized conditions even homoepitaxial layers can be obtained, while rod-like structures are obtained on SCAM substrates. The chemistry and the driving forces behind the two processes are considered in detail and the temperature dependence of the solution composition has been calculated. The driving force for the ZnO crystal growth in the standard hydrothermal technique is the difference in the ZnO solubility in alkaline solutions at different temperatures. In contrast, the driving force for the chemical bath deposition of ZnO at low temperatures is the decay of zinc ion complex molecules with increasing temperature.

  13. Annealing effect on structural and optical properties of chemical bath deposited MnS thin film

    NASA Astrophysics Data System (ADS)

    Ulutas, Cemal; Gumus, Cebrail

    2016-03-01

    MnS thin film was prepared by the chemical bath deposition (CBD) method on commercial microscope glass substrate deposited at 30 °C. The as-deposited film was given thermal annealing treatment in air atmosphere at various temperatures (150, 300 and 450 °C) for 1 h. The MnS thin film was characterized by using X-ray diffraction (XRD), UV-vis spectrophotometer and Hall effect measurement system. The effect of annealing temperature on the structural, electrical and optical properties such as optical constants of refractive index (n) and energy band gap (Eg) of the film was determined. XRD measurements reveal that the film is crystallized in the wurtzite phase and changed to tetragonal Mn3O4 phase after being annealed at 300 °C. The energy band gap of film decreased from 3.69 eV to 3.21 eV based on the annealing temperature.

  14. Chemical-Bath-Deposited Indium Oxide Microcubes for Solar Water Splitting.

    PubMed

    Mali, Mukund G; Yoon, Hyun; Kim, Hayong; Joshi, Bhavana; Al-Deyab, Salem S; Yoon, Sam S

    2015-11-16

    We fabricated films of cubic indium oxide (In2O3) by chemical bath deposition (CBD) for solar water splitting. The fabricated films were characterized by X-ray diffraction analysis, Raman scattering, X-ray photoelectron spectroscopy, and scanning electron microscopy, and the three-dimensional microstructure of the In2O3 cubes was elucidated. The CBD deposition time was varied, to study its effect on the growth of the In2O3 microcubes. The optimal deposition time was determined to be 24 h, and the corresponding film exhibited a photocurrent density of 0.55 mA cm(-2). Finally, the film stability was tested by illuminating the films with light from an AM 1.5 filter with an intensity of 100 mW cm(-2). PMID:26332269

  15. Chemical Bath Deposition of Aluminum Oxide Buffer on Curved Surfaces for Growing Aligned Carbon Nanotube Arrays.

    PubMed

    Wang, Haitao; Na, Chongzheng

    2015-07-01

    Direct growth of vertically aligned carbon nanotube (CNT) arrays on substrates requires the deposition of an aluminum oxide buffer (AOB) layer to prevent the diffusion and coalescence of catalyst nanoparticles. Although AOB layers can be readily created on flat substrates using a variety of physical and chemical methods, the preparation of AOB layers on substrates with highly curved surfaces remains challenging. Here, we report a new solution-based method for preparing uniform layers of AOB on highly curved surfaces by the chemical bath deposition of basic aluminum sulfate and annealing. We show that the thickness of AOB layer can be increased by extending the immersion time of a substrate in the chemical bath, following the classical Johnson-Mehl-Avrami-Kolmogorov crystallization kinetics. The increase of AOB thickness in turn leads to the increase of CNT length and the reduction of CNT curviness. Using this method, we have successfully synthesized dense aligned CNT arrays of micrometers in length on substrates with highly curved surfaces including glass fibers, stainless steel mesh, and porous ceramic foam. PMID:26053766

  16. Chemical bath deposition of Cu3BiS3 thin films

    NASA Astrophysics Data System (ADS)

    Deshmukh S., G.; Panchal A., K.; Vipul, Kheraj

    2016-05-01

    First time, copper bismuth sulfide (Cu3BiS3) thin films were synthesized on the glass substrate using simple, low-cost chemical bath deposition (CBD) technique. The synthesized parameters such as temperature of bath, pH and concentration of precursors were optimized for the deposition of uniform, well adherent Cu3BiS3 thin films. The optical, surface morphology and structural properties of the Cu3BiS3 thin films were studied using UV-VIS-NIR spectra, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The as- synthesized Cu3BiS3 film exhibits a direct band gap 1.56 to 1.58 eV having absorption coefficient of the order of 105 cm-1. The XRD declares the amorphous nature of the films. SEM images shows films were composed of close-packed fine spherical nanoparticles of 70-80 nm in diameter. The chemical composition of the film was almost stoichiometric. The optical study indicates that the Cu3BiS3 films can be applied as an absorber layer for thin film solar cells.

  17. Synthesis and Characterization of SnO2 Thin Films by Chemical Bath Deposition

    NASA Astrophysics Data System (ADS)

    Rifai, Aditia; Iqbal, Muhammad; Nugraha; Nuruddin, Ahmad; Suyatman; Yuliarto, Brian

    2011-12-01

    SnO2 thin films were deposited on glass substrate by chemical bath deposition (CBD) with stannous chloride (SnCl2..2H2O) as a precursor and urea (CO(NH2)2) as a buffer. X-Ray Diffraction (XRD) are used to characterize the structure of the films; the surface morphology of the films were observed by Scanning Electron Microscope (SEM). Using this techniques, we specify the effect of stannous chloride concentration and weight ratio of urea/H2O on the crystallinity and morphology of these films. The rutile structure corresponding (110), (101) and (211) planes of SnO2 is obtained. The increasing of stannous chloride concentration and the decreasing weight ratio of urea/H2O is found to improve the crystallinity of the film. The average diameter of grain size is about 96 nm.

  18. Chemical bath deposition of cadmium sulfide on graphene-coated flexible glass substrate

    SciTech Connect

    Seo, Won-Oh; Jung, Younghun; Kim, Jihyun; Kim, Jiwan; Kim, Donghwan

    2014-03-31

    We demonstrate a flexible structure of cadmium sulfide (CdS) on graphene-coated glass substrate, where CdS was deposited by the chemical bath deposition method on defective tri-layer graphene. The defects in graphene, confirmed by micro-Raman spectroscopy, were created by a ultra-violet treatment with varying exposure time from 10 to 60 min. The number of defect sites in the graphene as a seed layer was related to the quality of the CdS thin films determined from the results from X-ray diffraction, optical transmittance, scanning electron microscopy, and room temperature micro-photoluminescence. Our film-on-substrate structure of CdS-graphene-on-glass was maintained up to a tensile strain of 0.3%, where graphene with a high failure strain was employed as a transparent conductive layer.

  19. Combinatorial Chemical Bath Deposition of CdS Contacts for Chalcogenide Photovoltaics.

    PubMed

    Mokurala, Krishnaiah; Baranowski, Lauryn L; de Souza Lucas, Francisco W; Siol, Sebastian; van Hest, Maikel F A M; Mallick, Sudhanshu; Bhargava, Parag; Zakutayev, Andriy

    2016-09-12

    Contact layers play an important role in thin film solar cells, but new material development and optimization of its thickness is usually a long and tedious process. A high-throughput experimental approach has been used to accelerate the rate of research in photovoltaic (PV) light absorbers and transparent conductive electrodes, however the combinatorial research on contact layers is less common. Here, we report on the chemical bath deposition (CBD) of CdS thin films by combinatorial dip coating technique and apply these contact layers to Cu(In,Ga)Se2 (CIGSe) and Cu2ZnSnSe4 (CZTSe) light absorbers in PV devices. Combinatorial thickness steps of CdS thin films were achieved by removal of the substrate from the chemical bath, at regular intervals of time, and in equal distance increments. The trends in the photoconversion efficiency and in the spectral response of the PV devices as a function of thickness of CdS contacts were explained with the help of optical and morphological characterization of the CdS thin films. The maximum PV efficiency achieved for the combinatorial dip-coating CBD was similar to that for the PV devices processed using conventional CBD. The results of this study lead to the conclusion that combinatorial dip-coating can be used to accelerate the optimization of PV device performance of CdS and other candidate contact layers for a wide range of emerging absorbers. PMID:27479495

  20. Chemical-bath deposition of ZnSe thin films: Process and material characterization

    SciTech Connect

    Dona, J.M.; Herrero, J.

    1995-03-01

    Chemical-bath deposition of ZnSe thin films from NH{sub 3}/NH{sub 2}-NH{sub 2}/SeC(NH{sub 2}){sub 2}/Na{sub 2}SO{sub 3}/ZnSO{sub 4} solutions has been studied. The effect of various process parameters on the growth and the film quality is presented. A first approach to a mechanistic interpretation of the chemical process, based on the influence of the process parameters on the film growth rate, is reported. The structural, optical, chemical, and electrical properties of the ZnSe thin-films deposited by this method have been studied. The electron diffraction (EDS) analysis shows that the films are microcrystalline with mixed cubic and hexagonal structure. EDS analysis has demonstrated that the films are highly stoichiometric. Scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy studies of the ZnSe thin films deposited by this method show that the films are continuous and homogeneous. Optical measurements have allowed the authors to detect the presence of the spin-orbit splitting effect in this material. Electrical conductivity measurements have shown the highly resistive nature of these films ({rho} {approximately} 10{sup 9} {Omega} cm).

  1. Characterization of PbS/PVA/GQDs nanocomposite prepared by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Tohidi, Tavakkol; Jamshidi-Ghaleh, Kazem; Mohammad-Rezaei, Rahim

    2014-10-01

    This work reports synthesis of PbS quantum dots (QDs) embedded in the poly-vinyl alcohol (PVA) in the presence of graphene quantum dots (GQDs) by the low cost and simple method of chemical bath deposition. The as-synthesized products were characterized by X-ray diffraction, transmission electron microscope and optical studies; absorption and photoluminescence measurements. Results showed that in comparison with GQDs and PbS/PVA, photoluminescence intensity of PbS/PVA/GQDs was improved and this could be attributed to rigidity of the local environment, PVA passivation and energy transformation between GQDs and PbS QDs. These analyses determined good distribution of PbS QDs on GQDs planes which is promising for practical applications in nanotechnology.

  2. Superhydrophobic poly(vinylidene fluoride) film fabricated by alkali treatment enhancing chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Zheng, Zhenrong; Gu, Zhenya; Huo, Ruiting; Luo, Zhishan

    2010-01-01

    Based on the lotus effect principle, the superhydrophobic poly(vinylidene fluoride) (PVDF) film was successfully prepared by the method of alkali treatment enhancing chemical bath deposition. The surface of PVDF film prepared in this work was constructed by many smooth and regular microreliefs. Oxygen-containing functional groups were introduced in PVDF film by treatment with aqueous NaOH solution. The nano-scale peaks on the top of the microreliefs were implemented by the reaction between dimethyldichlorosilane/methyltrichlorosilane solution and the oxygen-containing functional groups of PVDF film. The micro- and nano-scale structures, similar to the lotus leaf, was clearly observed on PVDF film surface by scanning electronic microscopy (SEM) and atomic force microscope (AFM). The water contact angle and sliding angle on the fabricated lotus-leaf-like PVDF film surface were 157° and 1°, respectively, exhibiting superhydrophobic property and self-cleaning property.

  3. Comprehensive study of ZnO nanostructures grown using chemical bath deposition: from growth to application

    NASA Astrophysics Data System (ADS)

    Urgessa, Z. N.; Murape, D. M.; Oluwafemi, O. S.; Venter, A.; Wagner, M.; Botha, J. R.

    2011-12-01

    ZnO nanostructures were grown using a simple and environmentally friendly chemical bath deposition technique on pre-treated p-type silicon substrate at temperatures below 100°C. The effects of growth parameters like seed layer density, growth time, growth temperature, precursor concentration and annealing temperature on the structural, morphological, electrical and optical properties of ZnO nanorods were systematically studied using field emission scanning electron microscopy, X-ray diffraction, photoluminescence spectroscopy and current-voltage measurements. A variety of architectures is demonstrated, ranging from single crystalline nanoparticles and c-axis orientated nanorods to highly compact crystalline thin films. Post-growth annealing at different temperatures profoundly affects the optical properties of the nanorods by, for example, reducing hydrogen- and intrinsic defect-related emission. The rectifying properties of the ZnO/Si heterojunction are discussed.

  4. Photoconducting nanocrystalline lead sulphide thin films obtained by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Kotadiya, Naresh B.; Kothari, Anjana J.; Tiwari, Devendra; Chaudhuri, Tapas K.

    2012-09-01

    A chemical bath deposition method of preparing photoconducting nanocrystalline lead sulphide (PbS) thin films at room temperature (RT) is described. The aqueous bath of lead acetate, thiourea, and ammonium hydroxide produce films of about 100 nm thicknesses in 45 minutes. X-ray diffraction (XRD) studies show that these films are nanocrystalline cubic PbS with 10 nm crystallite size. Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) revealed that the films consist of spherical grains of sizes 100 to 200 nm. The transmission spectra of the films show onset of absorption edge around 850 nm and the bandgap is around 1.65 eV. The films are p-type with dark conductivity of 2.5×10-3 S/cm and mobility of 0.07 cm2/Vṡs. The photosensitivity is 6-7 for an illumination of 80 mW/cm2 from a halogen lamp (50 W, 12 V). Transient photoconductivity measurements reveal short and long life times of minority carriers. Thermoelectric and photothermoelectric studies show that photoconductivity in these films is mainly due to photogenerated majority carriers.

  5. Preparation and properties of zinc blende and orthorhombic SnS films by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Gao, Chao; Shen, Honglie; Sun, Lei

    2011-05-01

    SnS (stannous sulfide) films were prepared by chemical bath deposition in which a novel chelating reagent ammonium citrate was used. The film has a zinc blende structure or an orthorhombic structure which is determined by the pH value and the temperature of the deposition solution. The reason for this result is considered to be that SnS films prepared under different conditions have different deposition mechanisms (ion-by-ion mechanism for the zinc blende structured SnS and hydroxide cluster mechanism for the orthorhombic structured SnS). The prepared SnS films are homogeneous and well adhered. SEM images show that the SnS films with different structures have different surface morphologies. Electrical test shows that the resistivity of the films is as low as 420 Ω cm and 3300 Ω cm for orthorhombic and zinc blende SnS films, respectively, which are much lower than the ever reported values. Persistent photoconductivity (PPC) phenomena are observed for both the films with zinc blende and orthorhombic structures by photo-current responses measurement. The optical bandgaps of the SnS films are determined to be 1.75 eV and 1.15 eV for zinc blende structure and orthorhombic structure, respectively.

  6. Chemical bath deposition of semiconductor thin films & nanostructures in novel microreactors

    NASA Astrophysics Data System (ADS)

    McPeak, Kevin M.

    Chemical bath deposition (CBD) offers a simple and inexpensive route to deposit semiconductor nanostructures and thin films, but lack of fundamental understanding and control of the underlying chemistry has limited its versatility. CBD is traditionally performed in a batch reactor, requiring only a substrate to be immersed in a supersaturated solution of aqueous precursors such as metal salts, complexing agents, and pH buffers. Highlights of CBD include low cost, operation at low temperature and atmospheric pressure, and scalability to large area substrates. In this dissertation, I explore CBD of semiconductor thin films and nanowire arrays in batch and continuous flow microreactors. Microreactors offer many advantages over traditional reactor designs including a reduction in mass transport limitations, precise temperature control and ease of production scale-up by "numbering up". Continuous flow micoreactors offer the unique advantage of providing reaction conditions that are time-invariant but change smoothly as a function of distance down the reaction channel. Growth from a bath whose composition changes along the reactor length results in deposited materials whose properties vary as a function of position on the substrate, essentially creating a combinatorial library. These substrates can be rapidly characterized to identify relationships between growth conditions and material properties or growth mechanisms. I have used CBD in a continuous flow microreactor to deposit ZnO nanowire arrays and CdZnS films whose optoelectronic properties vary as a function of position. The spatially-dependent optoelectronic properties of these materials have been correlated to changes in the composition, structure or growth mechanisms of the materials and ultimately their growth conditions by rigorous spatial characterization. CBD in a continuous flow microreactor, coupled with spatial characterization, provides a new route to understanding the connection between CBD growth

  7. Synthesis of CdS nanostructures using template-assisted ammonia-free chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Preda, N.; Enculescu, M.; Gherendi, F.; Matei, E.; Toimil-Molares, M. E.; Enculescu, I.

    2012-09-01

    CdS micro- and nano-structures (micro/nanotubes and nanostructured films) were obtained by ammonia-free chemical bath deposition using polymer templates (ion track-etched polycarbonate membranes and poly(styrene-hydroxyethyl methacrylate) nanosphere arrays). The semiconductor structures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), optical absorption, photoluminescence and electrical measurements. The diameters of CdS tubes are between 300 nm and few microns and the lengths are up to tens of micrometers. The SEM images prove that the CdS films are nanostructured due to the deposition on the polymer nanosphere arrays. For both CdS structures (tubes and films) the XRD patterns show a hexagonal phase. The optical studies reveal a band gap value of about 2.5-2.6 eV and a red luminescence at ˜1.77 eV. A higher increase of conductivity is observed for illuminating the CdS nanostructured film when compared to the simple semiconductor film. This is a consequence of the periodic patterning induced by the polymer nanosphere array.

  8. Tuning the morphology of metastable MnS films by simple chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Dhandayuthapani, T.; Girish, M.; Sivakumar, R.; Sanjeeviraja, C.; Gopalakrishnan, R.

    2015-10-01

    In the present investigation, we have prepared the spherical particles, almond-like, and cauliflower-like morphological structures of metastable MnS films on glass substrate by chemical bath deposition technique at low temperature without using any complexing or chelating agent. The morphological change of MnS films with molar ratio may be due to the oriented aggregation of adjacent particles. The compositional purity of deposited film was confirmed by the EDAX study. X-ray diffraction and micro-Raman studies confirm the sulfur source concentration induced enhancement in the crystallization of films with metastable MnS phase (zinc-blende β-MnS, and wurtzite γ-MnS). The shift in PL emission peak with molar ratio may be due to the change in optical energy band gap of the MnS, which was further confirmed by the optical absorbance study. The paramagnetic behavior of the sample was confirmed by the M-H plot.

  9. Effect of Reaction Temperature of CdS Buffer Layers by Chemical Bath Deposition Method.

    PubMed

    Kim, Hye Jin; Kim, Chae-Woong; Jung, Duk Young; Jeong, Chaehwan

    2016-05-01

    This study investigated CdS deposition on a Cu(In,Ga)Se2 (CIGS) film via chemical bath deposition (CBD) in order to obtain a high-quality optimized buffer layer. The thickness and reaction temperature (from 50 degrees C to 65 degrees C) were investigated, and we found that an increase in the reaction temperature during CBD, resulted in a thicker CdS layer. We obtained a thin film with a thickness of 50 nm at a reaction temperature of 60 degrees C, which also exhibited the highest photoelectric conversion efficiency for use in solar cells. Room temperature time-resolved photoluminescence (TR-PL) measurements were performed on the Cu(In,Ga)Se2 (CIGS) thin film and CdS/CIGS samples to determine the recombination process of the photo-generated minority carrier. The device performance was found to be dependent on the thickness of the CdS layer. As the thickness of the CdS increases, the fill factor and the series resistance increased to 61.66% and decreased to 8.35 Ω, respectively. The best condition was observed at a reaction temperature of 60 degrees C, and its conversion efficiency was 12.20%. PMID:27483883

  10. Electrical characteristics of (n)Si/(p)PbS heterojunction prepared by chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Hussain, Amir; Singh, Heisnam Shanjit; Rahman, Atowar

    2016-01-01

    Zn doped nanocrystalline PbS thin films is deposited on single crystal (n)-Si substrate by chemical bath deposition to form (n)Si/(p)PbS heterojunction structure. In order to study the current transport mechanism in (n)Si/(p)PbS heterojunction, the forward current-voltage characteristics is measured within the temperature 300 K - 340 K and capacitance-voltage characteristics is measured at a frequency of 1 kHz at 300 K. The forward current is greatly enhanced with increasing temperature whereas the reverse current is increased nominally. Junction parameters such as ideality factors, barrier heights, saturation current density, Richardson constant, etc. are determined from the I-V characteristics. The ideality factors are found to decrease with increase in temperature. The J-V characteristics under illumination showed poor photovoltaic effect of the junction. The higher value of ideality factor and poor photovoltaic conversion efficiency are due to the presence of interfacial layer, large series resistance and high defect density.

  11. Chemical bath deposition and characterization of electrochromic thin films of sodium vanadium bronzes

    SciTech Connect

    Najdoski, Metodija; Koleva, Violeta; Demiri, Sani

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer We report a new chemical bath method for the deposition of vanadium bronze thin films. Black-Right-Pointing-Pointer The films are phase mixture of NaV{sub 6}O{sub 15} and Na{sub 1.1}V{sub 3}O{sub 7.9} with 10.58% lattice water. Black-Right-Pointing-Pointer The as-deposited vanadium bronze films exhibit two-step electrochromism. Black-Right-Pointing-Pointer They change their yellow-orange color to green and then from green to blue color. Black-Right-Pointing-Pointer The method allows the preparation of films on substrates with low melting point. -- Abstract: Thin yellow-orange films of sodium vanadium oxide bronzes have been prepared from a sodium-vanadium solution (1:1) at 75 Degree-Sign C and pH = 3. The composition, structure and morphology of the films have been studied by XRD, IR spectroscopy, TG and SEM-EDX analyses. It has been established that the prepared films are a phase mixture of hydrated NaV{sub 6}O{sub 15} (predominant component) and Na{sub 1.1}V{sub 3}O{sub 7.9} with total water content of 10.58%. The sodium vanadium bronze thin films exhibit two-step electrochromism followed by color change from yellow-orange to green, and then from green to blue. The cyclic voltammetry measurements on the as-deposited and annealed vanadium bronze films reveal the existence of different oxidation/reduction vanadium sites which make these films suitable for electrochromic devices. The annealing of the films at 400 Degree-Sign C changes the composition, optical and electrochemical properties.

  12. Study of the morphology of ZnS thin films deposited on different substrates via chemical bath deposition.

    PubMed

    Gómez-Gutiérrez, Claudia M; Luque, P A; Castro-Beltran, A; Vilchis-Nestor, A R; Lugo-Medina, Eder; Carrillo-Castillo, A; Quevedo-Lopez, M A; Olivas, A

    2015-01-01

    In this work, the influence of substrate on the morphology of ZnS thin films by chemical bath deposition is studied. The materials used were zinc acetate, tri-sodium citrate, thiourea, and ammonium hydroxide/ammonium chloride solution. The growth of ZnS thin films on different substrates showed a large variation on the surface, presenting a poor growth on SiO2 and HfO2 substrates. The thin films on ITO substrate presented a uniform and compact growth without pinholes. The optical properties showed a transmittance of about 85% in the visible range of 300-800 nm with band gap of 3.7 eV. PMID:26011683

  13. Surface studies, structural characterization and quantity determination of PbSe nanocrystals deposited by chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Ghobadi, Nader; Hatam, Ebrahim Gholami

    2015-05-01

    High quality PbSe nanostructural films are prepared by a chemical bath deposition (CBD) method. The experimental surface studies including scanning electron microscopy (SEM) and X-ray diffraction (XRD) have been used to analyze PbSe nanostructure indicated high purity of sample without cracks or holes in nanostructure scale. Quantity of material is relatively hard to measure accurately for thin films. Rutherford Backscattering Spectroscopy (RBS) was used to obtain stoichiometry as well as thin film thickness. For all nanoparticles size (50-250 nm) we found that the Pb to Se ratio (Pb:Se) variation in depth is approximately constant value of 0.42±0.06 until near to the substrate where it's value diminishes.

  14. Investigation of chemical bath deposition of CdO thin films using three different complexing agents

    NASA Astrophysics Data System (ADS)

    Khallaf, Hani; Chen, Chia-Ta; Chang, Liann-Be; Lupan, Oleg; Dutta, Aniruddha; Heinrich, Helge; Shenouda, A.; Chow, Lee

    2011-09-01

    Chemical bath deposition of CdO thin films using three different complexing agents, namely ammonia, ethanolamine, and methylamine is investigated. CdSO 4 is used as Cd precursor, while H 2O 2 is used as an oxidation agent. As-grown films are mainly cubic CdO 2, with some Cd(OH) 2 as well as CdO phases being detected. Annealing at 400 °C in air for 1 h transforms films into cubic CdO. The calculated optical band gap of as-grown films is in the range of 3.37-4.64 eV. Annealed films have a band gap of about 2.53 eV. Rutherford backscattering spectroscopy of as-grown films reveals cadmium to oxygen ratio of 1.00:1.74 ± 0.01 while much better stoichiometry is obtained after annealing, in accordance with the X-ray diffraction results. A carrier density as high as 1.89 × 10 20 cm -3 and a resistivity as low as 1.04 × 10 -2 Ω-cm are obtained.

  15. Investigation of chemical bath deposition of ZnO thin films using six different complexing agents

    NASA Astrophysics Data System (ADS)

    Khallaf, Hani; Chai, Guangyu; Lupan, Oleg; Heinrich, Helge; Park, Sanghoon; Schulte, Alfons; Chow, Lee

    2009-07-01

    Chemical bath deposition of ZnO thin films using six different complexing agents, namely ammonia, hydrazine, ethanolamine, methylamine, triethanolamine and dimethylamine, is investigated. As-grown films were mainly ZnO2 with a band gap around 4.3 eV. Films annealed at 400 °C were identified as ZnO with a band gap around 3.3 eV. X-ray diffraction and micro-Raman spectroscopy revealed that as-grown films consist mainly of cubic zinc peroxide that was transformed into hexagonal ZnO after annealing. Rutherford backscattering spectroscopy (RBS) detected excess oxygen content in ZnO films after annealing. Fourier transform infrared spectroscopy of as-grown films showed a broad absorption band around 3300 cm-1 suggesting that the as-grown films may consist of a mixture of zinc peroxide and zinc hydroxide. X-ray photoelectron spectroscopy multiplex spectra of the O 1s peak were found to be consistent with film stoichiometry revealed by RBS. High-resolution transmission electron micrographs showed small variations of the order of 10 nm in film thickness which corresponds to the average grain size. A carrier density as high as 2.24×1019 cm-3 and a resistivity as low as 6.48 × 10-1 Ω cm were obtained for films annealed at 500 °C in argon ambient.

  16. Optical and Electrical Properties of Pure and Y-Doped n-SnSe Films Deposited by Chemical Bath Deposition

    NASA Astrophysics Data System (ADS)

    He, H. Y.

    2015-09-01

    Pure and Y3+-doped SnSe films were fabricated by chemical bath deposition. The deposited films were characterized by x-ray diffraction, scanning electron microscopy, x-ray photoelectron spectroscopy, ultraviolet-visible spectrophotometry, photoluminescence spectrophotometry, and electrical conduction measurement. Since the films were deposited from the precursor solution with Se/Sn < 1, the Se/Sn molar ratios in the films was also smaller than the stoichiometric ratio. The films had thicknesses of ~409-615 nm and average transmittances of ~73.45-84.10% in the wavelength range of 350-850 nm. The direct and indirect optical band gaps estimated from the optical spectra with two methods of calculating absorption coefficiency. These bandgap values increased as decreasing Y3+-doping content. The films also showed a strong emission centered at ~699 nm and a weak emission centered at ~510 nm. The films showed n-type conduction and electrical resistance of ~5.83-96.40 × 10-3 Ω cm that decreased with increasing Y content. The refractive index, extinction coefficient, optical conductivity, and dielectric constant of the films were calculated with the transmittance and reflectance spectra.

  17. Structural and optical properties of nano-structured CdS thin films prepared by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Bai, Rekha; Kumar, Dinesh; Chaudhary, Sujeet; Pandya, Dinesh K.

    2016-05-01

    Cadmium sulfide (CdS) thin films have been deposited on conducting glass substrates by chemical bath deposition (CBD) technique. The effect of precursor concentration on the structural, morphological, compositional, and optical properties of the CdS films has been studied. Crystal structure of these CdS films is characterized by X-ray diffraction (XRD) and it reveals polycrystalline structure with mixture of cubic and wurtzite phases with grain size decreasing as precursor concentration is increased. Optical studies reveal that the CdS thin films have high transmittance in visible spectral region reaching 90% and the films possess direct optical band gap that decreases from 2.46 to 2.39 eV with decreasing bath concentration. Our study suggests that growth is nucleation controlled.

  18. Morphological control of PbS grown on functionalized self-assembled monolayers by chemical bath deposition.

    PubMed

    Yang, Jing; Walker, Amy V

    2014-06-17

    We have investigated the chemical bath deposition (CBD) of PbS on functionalized alkanethiolate self-assembled monolayers (SAMs) using time-of-flight secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy. The deposition mechanism involves both cluster-by-cluster and ion-by-ion growth. The dominant reaction pathway and the chemical composition and morphology of the deposited layer are dependent on both the SAM terminal group and the experimental conditions. On -COOH-terminated SAMs, three types of crystallites are observed: nanocrystals formed by heterogeneous ion-by-ion growth, larger needle-like particles, and ~2 μm particles deposited by homogeneous cluster-by-cluster deposition. The nanocrystals nucleate at Pb(2+)-carboxylate surface complexes, and so strongly adhere to the substrate. On -OH- and -CH3-terminated SAMs, only the micrometer-sized particles are formed by a cluster-by-cluster deposition mechanism. These particles do not adhere strongly to the SAM surface and can be easily removed. SIMS and XPS analyses indicate that the larger needle-like crystals and micrometer-sized particles are composed of oxidized lead sulfide and lead oxides, while the nanocrystals are composed of ≥85% PbS. Using sonication-assisted CBD, we demonstrate that PbS is deposited by ion-by-ion growth alone on -COOH-terminated SAMs. The deposited film is more compact with a smaller grain size and is >90% PbS. PMID:24854067

  19. Synthesis and characterization Bi2O2S thin film via chemical bath deposition at low pH

    NASA Astrophysics Data System (ADS)

    KARİPER, İ. Afşin

    2016-06-01

    Bismuth oxysulfide thin film was prepared using Bi(NO3)3 and Na2S as reactive. Since bismuth in the form of bismuth oxide is dissolved into water, bismuth and sulfide concentration of the chemical bath is very important. Bismuth oxysulfide (Bi2O2S) thin films were produced below pH 2. Tested bismuth and sulfide concentrations are as follows: 2 × 10- 1 M, 2 × 10- 2 M, 2 × 10- 3 M, 2 × 10- 4 M bismuth and 1 × 10- 1 M, 1 × 10- 2 M, 1 × 10- 3 M, 1 × 10- 4 M sulfide. The structure of the films was examined via X-ray diffraction (XRD). Optical properties, such as transmission and absorbance were measured with Ultra violet-visible spectrum, and then refractive index and reflectivity were calculated. The pH of chemical bath was stabilized below pH of 2 using 13.85 mL concentrated nitric acid. Deposition time and temperature of the baths were 4 h and 30 °C. It has been found that bismuth and sulfide concentrations affected the structure and thickness of the film. Also, optical band gap of the films varied with concentration, parallel to the change of the structure and film thickness.

  20. Synthesis and characterization Bi2O2S thin film via chemical bath deposition at low pH.

    PubMed

    Kariper, I Afşin

    2016-06-15

    Bismuth oxysulfide thin film was prepared using Bi(NO3)3 and Na2S as reactive. Since bismuth in the form of bismuth oxide is dissolved into water, bismuth and sulfide concentration of the chemical bath is very important. Bismuth oxysulfide (Bi2O2S) thin films were produced below pH2. Tested bismuth and sulfide concentrations are as follows: 2×10(-1)M, 2×10(-2)M, 2×10(-3)M, 2×10(-4)M bismuth and 1×10(-1)M, 1×10(-2)M, 1×10(-3)M, 1×10(-4)M sulfide. The structure of the films was examined via X-ray diffraction (XRD). Optical properties, such as transmission and absorbance were measured with Ultra violet-visible spectrum, and then refractive index and reflectivity were calculated. The pH of chemical bath was stabilized below pH of 2 using 13.85mL concentrated nitric acid. Deposition time and temperature of the baths were 4h and 30°C. It has been found that bismuth and sulfide concentrations affected the structure and thickness of the film. Also, optical band gap of the films varied with concentration, parallel to the change of the structure and film thickness. PMID:27043873

  1. The study of metal sulphide nanomaterials obtained by chemical bath deposition and hot-injection technique

    NASA Astrophysics Data System (ADS)

    Maraeva, E. V.; Alexandrova, O. A.; Forostyanaya, N. A.; Levitskiy, V. S.; Mazing, D. S.; Maskaeva, L. N.; Markov, V. Ph; Moshnikov, V. A.; Shupta, A. A.; Spivak, Yu M.; Tulenin, S. S.

    2015-11-01

    In this study lead sulphide - cadmium sulphide based layers were obtained through chemical deposition of water solutions and cadmium sulphide quantum dots were formed through hot-injection technique. The article discusses the results of surface investigations with the use of atomic force microscopy, Raman spectroscopy and photoluminescence measurements.

  2. The effects of porosity on optical properties of semiconductor chalcogenide films obtained by the chemical bath deposition

    PubMed Central

    2012-01-01

    This paper is dedicated to study the thin polycrystalline films of semiconductor chalcogenide materials (CdS, CdSe, and PbS) obtained by ammonia-free chemical bath deposition. The obtained material is of polycrystalline nature with crystallite of a size that, from a general point of view, should not result in any noticeable quantum confinement. Nevertheless, we were able to observe blueshift of the fundamental absorption edge and reduced refractive index in comparison with the corresponding bulk materials. Both effects are attributed to the material porosity which is a typical feature of chemical bath deposition technique. The blueshift is caused by quantum confinement in pores, whereas the refractive index variation is the evident result of the density reduction. Quantum mechanical description of the nanopores in semiconductor is given based on the application of even mirror boundary conditions for the solution of the Schrödinger equation; the results of calculations give a reasonable explanation of the experimental data. PMID:22931255

  3. Fabrication and morphology control of BaWO{sub 4} thin films by microwave assisted chemical bath deposition

    SciTech Connect

    Wang Rui; Liu Chen; Zeng Jia; Li KunWei; Wang Hao

    2009-04-15

    Highly crystallized barium tungstate (BaWO{sub 4}) thin films with dumbbell-like, kernel-like, bowknot-like and cauliflower-like microstructure were synthesized from an aqueous solution containing barium nitrate, ethylenediamine tetraacetate acid disodium and sodium tungstate, via mild microwave assisted chemical bath deposition process. The resulting BaWO{sub 4} films with different morphologies were characterized by X-ray diffraction spectrum, scanning electron microscope, Raman and photoluminescence spectra. The results indicate that the morphologies of final products significantly depend on the reaction conditions including the reaction time, the initial concentration of precursor reagent and the physicochemical characteristics of the substrates. Furthermore, the oriented aggregation mechanism is proposed as a possible formation mechanism of the films with specific morphologies. - Graphical abstract: Highly crystallized BaWO{sub 4} thin films with controllable morphologies have been synthesized via mild microwave assisted chemical bath deposition. The oriented aggregation mechanism has been proposed as the possible formation mechanism of specific films.

  4. Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution

    NASA Astrophysics Data System (ADS)

    Sandoval-Paz, M. G.; Rodríguez, C. A.; Porcile-Saavedra, P. F.; Trejo-Cruz, C.

    2016-07-01

    Copper (I) selenide thin films with orthorhombic and cubic structure were deposited on glass substrates by using the chemical bath deposition technique. The effects of the solution pH on the films growth and subsequently the structural, optical and electrical properties of the films were studied. Films with orthorhombic structure were obtained from baths wherein both metal complex and hydroxide coexist; while films with cubic structure were obtained from baths where the metal hydroxide there is no present. The structural modifications are accompanied by changes in bandgap energy, morphology and electrical resistivity of the films.

  5. Synthesis of nanostructured and microstructured ZnO and Zn(OH)2 on activated carbon cloth by hydrothermal and microwave-assisted chemical bath deposition methods

    NASA Astrophysics Data System (ADS)

    Mosayebi, Elham; Azizian, Saeid; Hajian, Ali

    2015-05-01

    Nanostructured and microstructured ZnO and Zn(OH)2 loaded on activated carbon cloth were synthesized by microwave-assisted chemical bath deposition and hydrothermal methods. By hydrothermal method the deposited sample on carbon fiber is pure ZnO with dandelion-like nanostructures. By microwave-assisted chemical bath method the structure and composition of deposited sample depends on solution pH. At pH = 9.8 the deposited sample on carbon fiber is pure ZnO with flower-like microstructure; but at pH = 10.8 the sample is a mixture of ZnO and Zn(OH)2 with flower-like and rhombic microstructures, respectively. The mechanism of crystal grow by microwave-assisted chemical bath method was investigated by SEM method at both pH.

  6. Structural and optical studied of nano structured lead sulfide thin films prepared by the chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Al Din, Nasser Saad; Hussain, Nabiha; Jandow, Nidhal

    2016-07-01

    Lead (II) Sulfide PbS thin films were deposited on glass substrates at 25°C by chemical bath deposition (CBD) method. The structural properties of the films were studied as a function of the concentration of Thiourea (CS (NH2)2) as Source of Sulfide and deposition time. The surface morphology of the films was characterized by X-ray diffraction and SEM. The obtained results showed that the as-deposited films Polycrystalline had cubic crystalline phase that belong to S.G: Fm3m. We found that they have preferred orientation [200]. Also the thickness of thin films decrease with deposition time after certain value and, it observed free sulfide had orthorhombic phase. Optical properties showed that the thin films have high transmission at visible range and low transmission at UV, IR range. The films of PbS have direct band gap (I.68 - 2.32 ev) at 300K the values of band energy decreases with increases thickness of the Lead (II) Sulfide films.

  7. Structural Properties and Electrochemical Performance of ZnO Nanosheets Grown Directly on Al substrate by Chemical Bath Deposition Techniques

    NASA Astrophysics Data System (ADS)

    Al-Asadi, Ahmed; Ferrera, Roberto; Henley, Luke; Lopez, Nestor; Carozo, Victor; Lin, Zhong; Terrones, Mauricio; Talapatra, Saikat

    We will report on the synthesis & electrochemical characterization of 2-dimentional zinc oxide grown directly on Al substrate by a simple chemical bath deposition method at low temperature (below 1000C). Detail structural characterizations of the synthesized ZnO sheets will be presented and discussed. The electrochemical performances of electrochemical double layer capacitors (EDLC) on electrodes fabricated using these materials were evaluated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy using various electrolytes. We found that high specific capacitance values (greater than 300 F/g) could be achieved using an aqueous electrolyte. The aforementioned results indicates the possibly for using 2-D ZnO architectures fabricated by this simple and cost efficient technique for future electrochemical energy storage devices.

  8. Structural and optical properties of Ni-doped CdS thin films prepared by chemical bath deposition method

    SciTech Connect

    Premarani, R.; Saravanakumar, S. Chandramohan, R.; Mahalingam, T.

    2015-06-24

    The structural and optical behavior of undoped Cadmiun Sulphide (CdS) and Ni-doped CdS thinfilms prepared by Chemical Bath Deposition (CBD) technique is reported. The crystallite sizes of the thinfilms have been characterized by X-ray diffraction pattern (XRD). The particle sizes increase with the increase of Ni content in the CdS thinfilms. Scanning Electron Microscope (SEM) results indicated that CdS thinfilms is made up of aggregate of spherical-like particles. The composition was estimated by Energy Dispersive Analysis of X-ray (EDX) and reported. Spectroscopic studies revealed considerable improvement in transmission and the band gap of the films changes with addition of Ni dopant that is associated with variation in crystallite sizes in the nano regime.

  9. Fabrication and characterization of ultraviolet photosensors from ZnO nanowires prepared using chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Al-Asadi, Ahmed S.; Henley, Luke Alexander; Ghosh, Sujoy; Quetz, Abdiel; Dubenko, Igor; Pradhan, Nihar; Balicas, Luis; Perea-Lopez, Nestor; Carozo, Victor; Lin, Zhong; Terrones, Mauricio; Talapatra, Saikat; Ali, Naushad

    2016-02-01

    Highly crystalline zinc oxide (ZnO) nanowires (NWs) were synthesized through chemical bath deposition (CBD) method by using a simple seeding technique. The process includes dispersion of commercially available ZnO nanoparticles through spraying on a desired substrate prior to the CBD growth. A typical growth period of 16 h produced ZnO NW assemblies with an average diameter of ˜45 nm and lengths of 1-1.3 μm, with an optical band gap of ˜3.61 eV. The as-prepared ZnO NWs were photoactive under ultra violet (UV) illumination. Photodetector devices fabricated using these NW assemblies demonstrated a high photoresponse factor of ˜40 and 120 at room temperature under moderate UV illumination power of ˜250 μW/cm2. These findings indicate the possibility of using ZnO NWs, grown using the simple method discussed in this paper, for various opto-electronic applications.

  10. Fabrication and morphology control of BaWO 4 thin films by microwave assisted chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Liu, Chen; Zeng, Jia; Li, KunWei; Wang, Hao

    2009-04-01

    Highly crystallized barium tungstate (BaWO 4) thin films with dumbbell-like, kernel-like, bowknot-like and cauliflower-like microstructure were synthesized from an aqueous solution containing barium nitrate, ethylenediamine tetraacetate acid disodium and sodium tungstate, via mild microwave assisted chemical bath deposition process. The resulting BaWO 4 films with different morphologies were characterized by X-ray diffraction spectrum, scanning electron microscope, Raman and photoluminescence spectra. The results indicate that the morphologies of final products significantly depend on the reaction conditions including the reaction time, the initial concentration of precursor reagent and the physicochemical characteristics of the substrates. Furthermore, the oriented aggregation mechanism is proposed as a possible formation mechanism of the films with specific morphologies.

  11. Role of the conducting layer substrate on TiO2 nucleation when using microwave activated chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Zumeta, I.; Espinosa, R.; Ayllón, J. A.; Vigil, E.

    2002-12-01

    Nanostructured TiO2 is used in novel dye sensitized solar cells. Because of their interaction with light, thin TiO2 films are also used as coatings for self-cleaning glasses and tiles. Microwave activated chemical bath deposition represents a simple and cost-effective way to obtain nanostructured TiO2 films. It is important to study, in this technique, the role of the conducting layer used as the substrate. The influence of microwave-substrate interactions on TiO2 deposition is analysed using different substrate positions, employing substrates with different conductivities, and also using different microwave radiation powers for film deposition. We prove that a common domestic microwave oven with a large cavity and inhomogeneous radiation field can be used with equally satisfactory results. The transmittance spectra of the obtained films were studied and used to analyse film thickness and to obtain gap energy values. The results, regarding different indium-tin oxide resistivities and different substrate positions in the oven cavity, show that the interaction of the microwave field with the conducting layer is determinant in layer deposition. It has also been found that film thickness increases with the power of the applied radiation while the gap energies of the TiO2 films decrease approaching the 3.2 eV value reported for bulk anatase. This indicates that these films are not crystalline and it agrees with x-ray spectra that do not reveal any peak.

  12. Effect of Thermal Annealing on the Band GAP and Optical Properties of Chemical Bath Deposited ZnSe Thin Films

    NASA Astrophysics Data System (ADS)

    Ezema, F. I.; Ekwealor, A. B. C.; Osuji, R. U.

    2006-05-01

    Zinc selenide (ZnSe) thin films were deposited on glass substrate using the chemical bath deposition method at room temperature from aqueous solutions of zinc sulphate and sodium selenosulfate in which sodium hydroxide was employed as complexing agents. The `as-deposited' ZnSe thin films are red in color and annealed in oven at 473 K for 1 hour and on a hot plate in open air at 333 K for 5 minutes, affecting the morphological and optical properties. Optical properties such as absorption coefficient a and extinction coefficient k, were determined using the absorbance and transmission measurement from Unico UV-2102 PC spectrophotometer, at normal incidence of light in the wavelength range of 200-1000 nm. The films have transmittance in VIS-NIR regions that range between 26 and 87%. From absorbance and transmittance spectra, the band gap energy determined ranged between 1.60 eV and 1.75 for the `as deposited' samples, and the annealed samples exhibited a band gap shift of 0.15 eV. The high transmittance of the films together with its large band gap made them good materials for selective coatings for solar cells.

  13. Single step synthesis of rutile TiO2 nanoflower array film by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Dhandayuthapani, T.; Sivakumar, R.; Ilangovan, R.

    2016-05-01

    Titanium oxide (TiO2) nanostructures such as nanorod arrays, nanotube arrays and nanoflower arrays have been extensively investigated by the researchers. Among them nanoflower arrays has shown superior performance than other nanostructures in Dye sensitized solar cell, photocatalysis and energy storage applications. Herein, a single step synthesis for rutile TiO2 nanoflower array films suitable for device applications has been reported. Rutile TiO2 nanoflower thin film was synthesized by chemical bath deposition method using NaCl as an additive. Bath temperature induced evolution of nanoflower thin film arrays was observed from the morphological study. X-ray diffraction study confirmed the presence of rutile phase polycrystalline TiO2. Micro-Raman study revealed the presence of surface phonon mode at 105 cm-1 due to the phonon confinement effect (finite size effect), in addition with the rutile Raman active modes of B1g (143 cm-1), Eg (442 cm-1) and A1g (607 cm-1). Further, the FTIR spectrum confirmed the presence of Ti-O-Ti bonding vibration. The Tauc plot showed the direct energy band gap nature of the film with the value of 2.9 eV.

  14. Hall Coefficient Determination and Electrical Properties of Chemical Bath-Deposited n-WO3 Thin Films

    NASA Astrophysics Data System (ADS)

    Amaechi, Ifeanyichukwu C.; Nwanya, Assumpta C.; Asogwa, Paul U.; Osuji, Rose U.; Maaza, Malik; Ezema, Fabian I.

    2015-04-01

    Nanocrystalline and porous chemical bath-deposited n-WO3 thin films at low temperature (318 K) are reported. The high-quality and well-reproducible films have been fabricated by acidic hydrolysis of tungstate ion followed by thermal annealing at 573 K for 1 h. X-ray diffraction analyses of the deposited WO3 films revealed that they were amorphous. However, an amorphous-to-crystalline transition with monoclinic phase was observed. Atomic force microscopy (AFM) analyses revealed a homogenous but irregular cluster of faceted spherically-shaped grains with pores. Scanning electron microscopy corroborated the AFM results. The optical absorption analysis of WO3 film showed that direct optical transition exists in the photon energy range 3.00-4.00 eV with bandgap of 3.70 eV. The refractive index developed peak at 315 nm in the dispersion region while the high frequency dielectric constant ɛ ∞, and the carrier concentration to effective mass ratio, N/m*, were found to be 1.37 and 1.45 × 1039 cm-3, respectively. The temperature dependence of the electrical resistivity of the deposited films follows the semiconductor behavior with thermal activation energy of 2.0 meV, while the Hall coefficient R H was determined to be 0.17 cm3/A s.

  15. Surface modification of cadmium sulfide thin film honey comb nanostructures: Effect of in situ tin doping using chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Wilson, K. C.; Basheer Ahamed, M.

    2016-01-01

    Even though nanostructures possess large surface to volume ratio compared to their thin film counterpart, the complicated procedure that demands for the deposition on a substrate kept them back foot in device fabrication techniques. In this work, a honey comb like cadmium sulfide (CdS) thin films nanostructure are deposited on glass substrates using simple chemical bath deposition technique at 65 °C. Energy band gaps, film thickness and shell size of the honey comb nanostructures are successfully controlled using tin (Sn) doping and number of shells per unit area is found to be maximum for 5% Sn doped (in the reaction mixture) sample. X-ray diffraction and optical absorption analysis showed that cadmium sulfide and cadmium hydroxide coexist in the samples. TEM measurements showed that CdS nanostructures are embedded in cadmium hydroxide just like "plum pudding". Persistent photoconductivity measurements of the samples are also carried out. The decay constants found to be increased with increases in Sn doping.

  16. Mimicry of sputtered i-ZnO thin films using chemical bath deposition for solution-processed solar cells.

    PubMed

    Della Gaspera, Enrico; van Embden, Joel; Chesman, Anthony S R; Duffy, Noel W; Jasieniak, Jacek J

    2014-12-24

    Solution processing provides a versatile and inexpensive means to prepare functional materials with specifically designed properties. The current challenge is to mimic the structural, optical, and/or chemical properties of thin films fabricated by vacuum-based techniques using solution-based approaches. In this work we focus on ZnO to show that thin films grown using a simple, aqueous-based, chemical bath deposition (CBD) method can mimic the properties of sputtered coatings, provided that the kinetic and thermodynamic reaction parameters are carefully tuned. The role of these parameters toward growing highly oriented and dense ZnO thin films is fully elucidated through detailed microscopic and spectroscopic investigations. The prepared samples exhibit bulk-like optical properties, are intrinsic in their electronic characteristics, and possess negligible organic contaminants, especially when compared to ZnO layers deposited by sol-gel or from nanocrystal inks. The efficacy of our CBD-grown ZnO thin films is demonstrated through the effective replacement of sputtered ZnO buffer layers within high efficiency solution processed Cu2ZnSnS4xSe4(1-x) solar cells. PMID:25506738

  17. Production of HfO2 thin films using different methods: chemical bath deposition, SILAR and sol-gel process

    NASA Astrophysics Data System (ADS)

    Kariper, İ. A.

    2014-08-01

    Hafnium oxide thin films (HOTFs) were successfully deposited onto amorphous glasses using chemical bath deposition, successive ionic layer absorption and reaction (SILAR), and sol-gel methods. The same reactive precursors were used for all of the methods, and all of the films were annealed at 300°C in an oven (ambient conditions). After this step, the optical and structural properties of the films produced by using the three different methods were compared. The structures of the films were analyzed by X-ray diffraction (XRD). The optical properties are investigated using the ultraviolet-visible (UV-VIS) spectroscopic technique. The film thickness was measured via atomic force microscopy (AFM) in the tapping mode. The surface properties and elemental ratios of the films were investigated and measured by scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX). The lowest transmittance and the highest reflectance values were observed for the films produced using the SILAR method. In addition, the most intense characteristic XRD peak was observed in the diffraction pattern of the film produced using the SILAR method, and the greatest thickness and average grain size were calculated for the film produced using the SILAR method. The films produced using SILAR method contained fewer cracks than those produced using the other methods. In conclusion, the SILAR method was observed to be the best method for the production of HOTFs.

  18. Some physical effects of reaction rate on PbS thin films obtained by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Altıokka, Barış; Baykul, Mevlana Celalettin; Altıokka, Mehmet Rıza

    2013-12-01

    Thin films of polycrystalline lead sulfide (PbS) have been deposited on glass substrates at 303±1 K using chemical bath deposition (CBD). The precipitation of PbS on solid surfaces under four different reaction conditions was performed using a sodium sulfite (Na2SO3) compound as an inhibitor. The kinetics model for the reaction between Pb2+ and S2- was developed according to the amounts of Pb2+ concentrations measured by atomic absorption spectroscopy (AAS) during the precipitation of PbS. The surface morphologies of PbS thin films were studied with a Scanning Electron Microscope (SEM). It was found that the precipitation rate effects the formation of pinhole. To obtain a good quality of thin films the optimum concentration of lead nitrate (Pb(NO3)2), sodium hydroxide (NaOH), thiourea (CS(NH2)2) and Na2SO3 in the final solution was determined to be 0.0089, 0.1460, 0.510 and 0.00023 M, respectively. The film structures were characterized by X-ray diffractometer (XRD). The XRD results showed that the films formed galena cubic structures which represent the natural mineral of PbS. The crystallite sizes of the films were found to be between 23 and 37 nm.

  19. RETRACTED: Ammonia-free method for synthesis of CdS nanocrystalline thin films through chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Karimi, M.; Rabiee, M.; Moztarzadeh, F.; Bodaghi, M.; Tahriri, M.

    2009-11-01

    This article has been retracted: please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief of Solid State Communications as the authors have plagiarized part of a paper that has also appeared in Current Applied Physics: Controlled synthesis, characterization and optical properties of CdS nanocrystalline thin films via chemical bath deposition (CBD) route Meysam Karimi, Mohammad Rabiee, Fathollah Moztarzadeh, Mohammadreza Tahriri and Masoud Bodaghi; Curr. Appl. Phys., 9 (2009) 1263-1268, doi: 10.1016/j.cap.2009.02.006. One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

  20. Coercivity enhancement of sintered Nd-Fe-B magnets by chemical bath deposition of TbCl{sub 3}

    SciTech Connect

    Guo, Shuai Zhang, Xiaofeng; Ding, Guangfei; Chen, Renjie; Yan, Aru; Lee, Don

    2014-05-07

    The chemical bath deposition (CBD) and the grain boundary diffusion method were combined to diffuse the heavy rare earth for obtain the thick magnets with high coercivity and low heavy rare earth. The jet mill powders were soaked into the alcohol solution of 0.2 wt. % TbCl{sub 3}. A thin layer of TbCl{sub 3} was wrapped to the surface of (PrNd){sub 2}Fe{sub 14}B powder particles. The coercivity of magnet is increased from 11.89 kOe to 14.72 kOe without significant reduction of remanence after grain boundary diffusion in the sintering and the annealing processes. The temperature coefficients of the remanence and the coercivity are improved by the substitution of PrNd by Tb in the surface of grains. The highly accelerated temperature/humidity stress test (HAST) results indicate that the CBD magnet has poor corrosion resistance, attributing to the present of Cl atoms in the grain boundaries.

  1. Annealed Ce3+-doped ZnO flower-like morphology synthesized by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Koao, Lehlohonolo F.; Dejene, Francis B.; Tsega, Moges; Swart, Hendrik C.

    2016-01-01

    We have successfully synthesized ZnO:xmol% Ce3+ (0≤x≤10 mol%) doped nanopowders via the chemical bath deposition method (CBD) technique at low temperature (80 °C) and annealed in air at 700 °C. The X-ray diffraction patterns showed that all the undoped and Ce-doped ZnO nanopowders have a hexagonal wurtzite polycrystalline structure with an average crystallite size of about 46 nm. Weak diffraction peaks related mainly to cerium oxide were also detected at higher concentrations of Ce3+ (x=5-10 mol%). The scanning electron microscopy study revealed that the nanopowder samples were assembled in flower-shaped undoped ZnO and pyramid-shaped Ce3+-doped ZnO nanostructures. The UV-vis spectra showed that the absorption edges shifted slightly to the longer wavelengths with the increase in the Ce3+ ions concentration. Moreover, the photoluminescence (PL) results showed a relative weak visible emission for the Ce3+-doped ZnO nanoparticles compared to the undoped ZnO. The effects of Ce3+-doping on the structure and PL of ZnO nanopowders are discussed in detail.

  2. Growth of CdS thin films on indium coated glass substrates via chemical bath deposition and subsequent air annealing

    NASA Astrophysics Data System (ADS)

    Ghosh, Biswajit; Kumar, Kamlesh; Singh, Balwant Kr; Banerjee, Pushan; Das, Subrata

    2014-11-01

    In the present work attempts were made to synthesize indium doped CdS films by fabricating In/CdS bilayers using CBD-CdS on vacuum evaporated In thin films and subsequent air annealing. 135 nm CdS films were grown onto 20 nm and 35 nm indium coated glass substrate employing chemical bath deposition technique. The In/CdS bilayers thus formed were subjected to heat treatment at the temperatures between 200 and 400 °C for 4 min in the muffle furnace to facilitate indium to diffuse into the CdS films. XRD pattern ascertained no noticeable shift in lattice constant implying grain boundary metal segregation, while secondary ion mass spectrometry indicated the diffusion profile of indium into CdS matrices. Mass spectrometry results showed that substantial diffusion of indium had been taken place within CdS at 400 °C. Dark and photocurrent with different illumination time were measured to ascertain the photosensitivity of pure and composite CdS films.

  3. Synthesis of Nanocrystalline SnOx (x = 1–2) Thin Film Using a Chemical Bath Deposition Method with Improved Deposition Time, Temperature and pH

    PubMed Central

    Ebrahimiasl, Saeideh; Yunus, Wan Md. Zin Wan; Kassim, Anuar; Zainal, Zulkarnain

    2011-01-01

    Nanocrystalline SnOx (x = 1–2) thin films were prepared on glass substrates by a simple chemical bath deposition method. Triethanolamine was used as complexing agent to decrease time and temperature of deposition and shift the pH of the solution to the noncorrosive region. The films were characterized for composition, surface morphology, structure and optical properties. X-ray diffraction analysis confirms that SnOx thin films consist of a polycrystalline structure with an average grain size of 36 nm. Atomic force microscopy studies show a uniform grain distribution without pinholes. The elemental composition was evaluated by energy dispersive X-ray spectroscopy. The average O/Sn atomic percentage ratio is 1.72. Band gap energy and optical transition were determined from optical absorbance data. The film was found to exhibit direct and indirect transitions in the visible spectrum with band gap values of about 3.9 and 3.7 eV, respectively. The optical transmittance in the visible region is 82%. The SnOx nanocrystals exhibit an ultraviolet emission band centered at 392 nm in the vicinity of the band edge, which is attributed to the well-known exciton transition in SnOx. Photosensitivity was detected in the positive region under illumination with white light. PMID:22163690

  4. Studies on growth and characterization of ternary CdS 1- xSe x alloy thin films deposited by chemical bath deposition technique

    NASA Astrophysics Data System (ADS)

    Chaudhari, J. B.; Deshpande, N. G.; Gudage, Y. G.; Ghosh, A.; Huse, V. B.; Sharma, Ramphal

    2008-08-01

    Ternary alloyed CdS 1- xSe x thin films of variable composition ' x' were grown by the simple and economical chemical bath deposition technique. The as-grown thin films were characterized for structural, compositional, surface morphological, optical and electrical studies. The X-ray diffraction (XRD) patterns of the sample indicated that all the samples were polycrystalline in nature with hexagonal structure. Scanning electron microscopy (SEM) micrographs showed uniform morphology with spherical shaped grains distributed over entire glass substrate. EDAX studies confirmed that the CdS 1- xSe x films were having approximately same stoichiometry initially as well as finally. Room temperature optical measurements showed that band gap engineering could be realized in CdS 1- xSe x thin films via modulation in composition ' x'. Electrical resistivity of CdS 1- xSe x thin films for various compositions was found to be low. The broad and fine tunable band gap properties of ternary CdS 1- xSe x thin films have potential applications in opto-electronic devices.

  5. On the sub-band gap optical absorption in heat treated cadmium sulphide thin film deposited on glass by chemical bath deposition technique

    SciTech Connect

    Chattopadhyay, P.; Karim, B.; Guha Roy, S.

    2013-12-28

    The sub-band gap optical absorption in chemical bath deposited cadmium sulphide thin films annealed at different temperatures has been critically analyzed with special reference to Urbach relation. It has been found that the absorption co-efficient of the material in the sub-band gap region is nearly constant up to a certain critical value of the photon energy. However, as the photon energy exceeds the critical value, the absorption coefficient increases exponentially indicating the dominance of Urbach rule. The absorption coefficients in the constant absorption region and the Urbach region have been found to be sensitive to annealing temperature. A critical examination of the temperature dependence of the absorption coefficient indicates two different kinds of optical transitions to be operative in the sub-band gap region. After a careful analyses of SEM images, energy dispersive x-ray spectra, and the dc current-voltage characteristics, we conclude that the absorption spectra in the sub-band gap domain is possibly associated with optical transition processes involving deep levels and the grain boundary states of the material.

  6. Effect of deposition temperature on the structural and optical properties of CdSe thin films synthesised by chemical bath deposition

    SciTech Connect

    Mohammed, Mudhafer Ali

    2013-12-16

    Cadmium selenide thin films were synthesized on glass substrates using chemical bath technique (CBD) at temperatures 320K, 330K, 340K,and 350K. The polycrystalline nature of the material was confirmed by X-ray diffraction technique and various structural parameters such as lattice parameters, grain size, dislocation density, and micro strain. The root mean square (RMS) roughness was obtained by using atomic force microscopy(AFM), which indicated a decreasing average roughness with the decrease of the bath temperature. Optical properties were carried out by UV-Visible transmittance spectra, and the band gap energy was determined.

  7. A chemical bath deposition route to facet-controlled Ag3PO4 thin films with improved visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Gunjakar, Jayavant L.; Jo, Yun Kyung; Kim, In Young; Lee, Jang Mee; Patil, Sharad B.; Pyun, Jae.-Chul.; Hwang, Seong-Ju

    2016-08-01

    A facile, economic, and reproducible chemical bath deposition (CBD) method is developed for the fabrication of facet-controlled Ag3PO4 thin films with enhanced visible light photocatalytic activity. The fine-control of bath temperature, precursor, complexing agent, substrate, and solution pH is fairly crucial in preparing the facet-selective thin film of Ag3PO4 nanocrystal. The change of precursor from silver nitrate to silver acetate makes possible the tailoring of the crystal shape of Ag3PO4 from cube to rhombic dodecahedron and also the bandgap tuning of the deposited films. The control of [Ag+]/[phosphate] ratio enables to maximize the loading amount of Ag3PO4 crystals per the unit area of the deposited film. All the fabricated Ag3PO4 thin films show high photocatalytic activity for visible light-induced degradation of organic molecules, which can be optimized by tailoring the crystal shape of the deposited crystals. This CBD method is also useful in preparing the facet-controlled hybrid film of Ag3PO4-ZnO photocatalyst. The present study clearly demonstrates the usefulness of the present CBD method for fabricating facet-controlled thin films of metal oxosalt and its nanohybrid.

  8. High-performance chemical-bath deposited CdS thin-film transistors with ZrO{sub 2} gate dielectric

    SciTech Connect

    Dondapati, Hareesh; Ha, Duc; Jenrette, Erin; Xiao, Bo; Pradhan, A. K.

    2014-08-04

    We demonstrate high performance chemical bath deposited CdS thin-film transistors (TFTs) using atomic layer deposited ZrO{sub 2} based high-k gate dielectric material. Our unique way of isolation of the CdS-based TFTs devices yielded significantly low leakage current as well as remarkable lower operating voltages (<5 V) which is four times smaller than the devices reported on CdS-based TFTs using SiO{sub 2} gate dielectric. Upon thermal annealing, the devices demonstrate even higher performance, including μ{sub FE} exceeding 4 ± 0.2 cm{sup 2} V{sup −1}S{sup −1}, threshold voltage V{sub T} of 3.8 V, and I{sub on-off} of 10{sup 4}–10{sup 5}, which hold much promise for applications in future electronic and optical devices.

  9. In Situ Localized Surface Plasmon Resonance (LSPR) Spectroscopy to Investigate Kinetics of Chemical Bath Deposition of CdS Thin Films

    SciTech Connect

    Kalyanaraman, Ramki; Taz, Humaira; Ruther, Rose E.; Nanda, Jagjit

    2015-02-11

    Techniques that can characterize the early stages of thin film deposition from liquid phase processes can aid greatly in our understanding of mechanistic aspects of chemical bath deposition (CBD). Here we have used localized surface plasmon resonance (LSPR) spectroscopy to monitor in-situ the kinetics of early-stage growth of cadmium sulfide (CdS) thin films on Ag nanoparticle on quartz substrates. Real-time shift during CdS deposition showed that the LSPR wavelength red shifted rapidly due to random deposition of CdS on the substrate, but saturated at longer times. LSPR modeling showed that these features could be interpreted as an initial deposition of CdS islands followed by preferential deposition onto itself. The CdS also showed significantly enhanced Raman signals up to 170 times due to surface enhanced raman scattering (SERS) from the CdS/Ag NP regions. The ex-situ SERS effect supported the LSPR shift suggesting that these techniques could be used to understand nucleation and growth phenomena from the liquid phase.

  10. In Situ Localized Surface Plasmon Resonance (LSPR) Spectroscopy to Investigate Kinetics of Chemical Bath Deposition of CdS Thin Films

    DOE PAGESBeta

    Kalyanaraman, Ramki; Taz, Humaira; Ruther, Rose E.; Nanda, Jagjit

    2015-02-11

    Techniques that can characterize the early stages of thin film deposition from liquid phase processes can aid greatly in our understanding of mechanistic aspects of chemical bath deposition (CBD). Here we have used localized surface plasmon resonance (LSPR) spectroscopy to monitor in-situ the kinetics of early-stage growth of cadmium sulfide (CdS) thin films on Ag nanoparticle on quartz substrates. Real-time shift during CdS deposition showed that the LSPR wavelength red shifted rapidly due to random deposition of CdS on the substrate, but saturated at longer times. LSPR modeling showed that these features could be interpreted as an initial deposition ofmore » CdS islands followed by preferential deposition onto itself. The CdS also showed significantly enhanced Raman signals up to 170 times due to surface enhanced raman scattering (SERS) from the CdS/Ag NP regions. The ex-situ SERS effect supported the LSPR shift suggesting that these techniques could be used to understand nucleation and growth phenomena from the liquid phase.« less

  11. Room temperature chemical bath deposition of cadmium selenide, cadmium sulfide and cadmium sulfoselenide thin films with novel nanostructures

    NASA Astrophysics Data System (ADS)

    VanderHyde, Cephas A.; Sartale, S. D.; Patil, Jayant M.; Ghoderao, Karuna P.; Sawant, Jitendra P.; Kale, Rohidas B.

    2015-10-01

    A simple, convenient and low cost chemical synthesis route has been used to deposit nanostructured cadmium sulfide, selenide and sulfoselenide thin films at room temperature. The films were deposited on glass substrates, using cadmium acetate as cadmium ion and sodium selenosulfate/thiourea as a selenium/sulfur ion sources. Aqueous ammonia was used as a complex reagent and also to adjust the pH of the final solution. The as-deposited films were uniform, well adherent to the glass substrate, specularly reflective and red/yellow in color depending on selenium and sulfur composition. The X-ray diffraction pattern of deposited cadmium selenide thin film revealed the nanocrystalline nature with cubic phase; cadmium sulfide revealed mixture of cubic along with hexagonal phase and cadmium sulfoselenide thin film were grown with purely hexagonal phase. The morphological observations revealed the growth and formation of interesting one, two and three-dimensional nanostructures. The band gap of thin films was calculated and the results are reported.

  12. Evolution of structural and optical properties of rutile TiO2 thin films synthesized at room temperature by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Mayabadi, A. H.; Waman, V. S.; Kamble, M. M.; Ghosh, S. S.; Gabhale, B. B.; Rondiya, S. R.; Rokade, A. V.; Khadtare, S. S.; Sathe, V. G.; Pathan, H. M.; Gosavi, S. W.; Jadkar, S. R.

    2014-02-01

    Nanocrystalline thin films of TiO2 were prepared on glass substrates from an aqueous solution of TiCl3 and NH4OH at room temperature using the simple and cost-effective chemical bath deposition (CBD) method. The influence of deposition time on structural, morphological and optical properties was systematically investigated. TiO2 transition from a mixed anatase-rutile phase to a pure rutile phase was revealed by low-angle XRD and Raman spectroscopy. Rutile phase formation was confirmed by FTIR spectroscopy. Scanning electron micrographs revealed that the multigrain structure of as-deposited TiO2 thin films was completely converted into semi-spherical nanoparticles. Optical studies showed that rutile thin films had a high absorption coefficient and a direct bandgap. The optical bandgap decreased slightly (3.29-3.07 eV) with increasing deposition time. The ease of deposition of rutile thin films at low temperature is useful for the fabrication of extremely thin absorber (ETA) solar cells, dye-sensitized solar cells, and gas sensors.

  13. Optimization of the ZnS Buffer Layer by Chemical Bath Deposition for Cu(In,Ga)Se2 Solar Cells.

    PubMed

    Jeon, Dong-Hwan; Hwang, Dae-Kue; Kim, Dae-Hwan; Kang, Jin-Kyu; Lee, Chang-Seop

    2016-05-01

    We evaluated a ZnS buffer layer prepared using a chemical bath deposition (CBD) process for application in cadmium-free Cu(In,Ga)Se2 (CIGS) solar cells. The ZnS buffer layer showed good transmittance (above 90%) in the spectral range from 300 to 800 nm and was non-toxic compared with the CdS buffer layers normally used in CIGS solar cells. The CBD process was affected by several deposition conditions. The deposition rate was dependent on the ammonia concentration (complexing agent). When the ammonia concentration was either too high or low, a decrease in the deposition rate was observed. In addition, post heat treatments at high temperatures had detrimental influences on the ZnS buffer layers because portions of the ZnS thin films were transformed into ZnO. With optimized deposition conditions, a CIGS solar cell with a ZnS buffer layer showed an efficiency of 14.18% with a 0.23 cm2 active area under 100 mW/cm2 illumination. PMID:27483938

  14. Quantum-dot-sensitized solar cells: Assembly of CdS-quantum-dots coupling techniques of self-assembled monolayer and chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Lin, Sheng-Chih; Lee, Yuh-Lang; Chang, Chi-Hsiu; Shen, Yu-Jen; Yang, Yu-Min

    2007-04-01

    Two methods, coupling self-assembled monolayer and chemical bath deposition (CBD), were utilized to assemble cadmium sulfide (CdS) quantum dots (QDs) onto mesoporous TiO2 films for dye-sensitized solar cell (DSSC) applications. Colloidal CdS QDs were first self-assembled on the TiO2 surface. CBD was then introduced to replenish the incorporated amount and increase the coverage ratio of CdS QDs on the TiO2 surface. The preassembled CdS QDs act as nucleation sites in the CBD process, forming a CdS nanofilm with an interfacial structure capable of inhibiting the recombination of injected electrons. An efficiency as high as 1.35% for the QD-sensitized DSSC was achieved using the present strategy.

  15. Chemical bath deposition growth and characterization of zinc oxide nanostructures on plain and platinum-coated glass substrates for hydrogen peroxide gas sensor application

    NASA Astrophysics Data System (ADS)

    Jamasali, Y. D. J.; Alguno, A. C.

    2015-06-01

    Growth of zinc oxide on plain and Pt-coated glass substrate via chemical bath deposition technique (CBD) were studied. Aqueous solutions of ammonium hydroxide (NH4OH) and zinc sulfate (ZnSO4) were used as the precursor substances in the synthesis. Ultraviolet-visible spectroscopy (UV-Vis) was performed to determine the energy band gap and X-ray diffraction (XRD) to examine crystallinity. Sensitivity measurements were carried out in order to examine its potential to be fabricated as hydrogen peroxide (H2O2) gas sensor. Experimental results in the sensitivity experiment show that in the presence of H2O2 gas, the resistance of ZnOincrease which can be used as the basis for H2O-2 detection. UV-Vis showed variation of energy band gap values but were all near the generally accepted value. XRD spectra further verify that ZnOwere indeed synthesized.

  16. Chemical bath deposition of textured and compact zinc oxide thin films on vinyl-terminated polystyrene brushes

    PubMed Central

    Blumenstein, Nina J; Hofmeister, Caroline G; Lindemann, Peter; Huang, Cheng; Baier, Johannes; Leineweber, Andreas; Wöll, Christof; Schimmel, Thomas

    2016-01-01

    Summary In this study we investigated the influence of an organic polystyrene brush on the deposition of ZnO thin films under moderate conditions. On a non-modified SiOx surface, island growth is observed, whereas the polymer brush induces homogeneous film growth. A chemical modification of the polystyrene brushes during the mineralization process occurs, which enables stronger interaction between the then polar template and polar ZnO crystallites in solution. This may lead to oriented attachment of the crystallites so that the observed (002) texture arises. Characterization of the templates and the resulting ZnO films were performed with ζ-potential and contact angle measurements as well as scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). Infrared spectroscopy (IR) measurements were used to investigate the polystyrene brushes before and after modification. PMID:26925358

  17. Chemical bath deposition of textured and compact zinc oxide thin films on vinyl-terminated polystyrene brushes.

    PubMed

    Blumenstein, Nina J; Hofmeister, Caroline G; Lindemann, Peter; Huang, Cheng; Baier, Johannes; Leineweber, Andreas; Walheim, Stefan; Wöll, Christof; Schimmel, Thomas; Bill, Joachim

    2016-01-01

    In this study we investigated the influence of an organic polystyrene brush on the deposition of ZnO thin films under moderate conditions. On a non-modified SiO x surface, island growth is observed, whereas the polymer brush induces homogeneous film growth. A chemical modification of the polystyrene brushes during the mineralization process occurs, which enables stronger interaction between the then polar template and polar ZnO crystallites in solution. This may lead to oriented attachment of the crystallites so that the observed (002) texture arises. Characterization of the templates and the resulting ZnO films were performed with ζ-potential and contact angle measurements as well as scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). Infrared spectroscopy (IR) measurements were used to investigate the polystyrene brushes before and after modification. PMID:26925358

  18. Photovoltaic p-n structure of MoSb2‑xCuxSe4/CdS absorber films obtained via chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Vijila, J. J. J.; Mohanraj, K.; Sivakumar, G.

    2016-07-01

    In this work, a novel mixed metal chalcogenide MoSb2‑xCuxSe4 nanocrystalline thin film was deposited for different copper concentrations (x = 0.0 M, 0.1 M, 0.2 M & 0.3 M) on glass substrate by chemical bath deposition method at room temperature. XRD patterns revealed the incorporation of copper content by the conversion of orthorhombic Sb2Se3 into Cu3SbSe3 with a shift to lower angles. Average crystallite was found to be 69 nm, 17 nm, 10 nm and 9 nm for the deposited films. FTIR spectra confirm the presence of functional groups of Trisodium citrate (TSC) and the metal oxide vibrations. FESEM analysis depicted the morphological changes with the addition of Cu content. UV–vis analysis shows higher absorption in the visible region and the band gap values are found to be 2.16–1.76 eV. Hall effect analysis confirms the p-type nature of the material. The photo-current analysis shows higher photo-conversion efficiency of 1.86% for 0.3 M copper content.

  19. Triton-X mediated interconnected nanowalls network of cadmium sulfide thin films via chemical bath deposition and their photoelectrochemical performance

    NASA Astrophysics Data System (ADS)

    Vanalakar, S. A.; Mali, S. S.; Jo, E. A.; Kim, J. Y.; Kim, J. H.; Patil, P. S.

    2014-10-01

    Thin films of cadmium sulfide (CdS) have been wet chemically deposited onto fluorine-doped tin oxide (FTO) coated conducting glass substrates by using non-ionic surfactant; Triton-X 100. An aqueous solution contains cadmium sulphate as a cadmium and thiourea as sulphur precursor. Ammonia used as a complexing agent. The results of measurements of the x-ray diffraction, Raman spectroscopy, optical spectroscopy, energy dispersive spectroscopy, scanning electron microscopy, Brunauer Emmett Teller (BET) surface areas and atomic force microscopy were used for the characterization of the films. These results revealed that the films are polycrystalline, consisting of CdS cubic phase. The films show a direct band gap with energy 2.39 eV. The films show interconnected nanowalls like morphology with well-defined surface area. Finally, the photoelectrochemical (PEC) performance of Triton-X mediated CdS thin film samples were studied. The sample shows photoelectrochemical (PEC) performance with maximum short circuit current density (Jsc) 1.71 mA/cm2 for larger area (1 cm2) solar cells.

  20. Role of ZnO thin film in the vertically aligned growth of ZnO nanorods by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Son, Nguyen Thanh; Noh, Jin-Seo; Park, Sungho

    2016-08-01

    The effect of ZnO thin film on the growth of ZnO nanorods was investigated. ZnO thin films were sputter-deposited on Si substrate with varying the thickness. ZnO nanorods were grown on the thin film using a chemical bath deposition (CBD) method at 90 °C. The ZnO thin films showed granular structure and vertical roughness on the surface, which facilitated the vertical growth of ZnO nanorods. The average grain size and the surface roughness of ZnO film increased with an increase in film thickness, and this led to the increase in both the average diameter and the average length of vertically grown ZnO nanorods. In particular, it was found that the average diameter of ZnO nanorods was very close to the average grain size of ZnO thin film, confirming the role of ZnO film as a seed layer for the vertical growth of ZnO nanorods. The CBD growth on ZnO seed layers may provide a facile route to engineering vertically aligned ZnO nanorod arrays.

  1. Microstructure, optical and structural characterization of Cd0.98Fe0.02S thin films co-doped with Zn by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Pitchaimani, K.; Amalraj, L.; Muthukumaran, S.

    2016-04-01

    Fe-doped CdS (Cd0.98Fe0.02S) and Fe, Zn co-doped CdS (Cd0.98-xZnxFe0.02S (x=0.02, 0.04, and 0.06)) thin films have been successfully deposited on glass substrate by chemical bath deposition technique using aqueous ammonia solution at pH = 9.5. Phase purity of the samples having cubic structure with (111) as the preferential orientation was confirmed by X-ray diffraction technique. Shift of X-ray diffraction peak position towards higher angle side and decrease of lattice parameters, volume and crystallite size confirmed the proper incorporation of Zn into Cd-Fe-S except Zn=6%. The compositional analysis (EDX) showed that Cd, Fe, Zn and S are present in the films. The enhanced band gap and higher transmittance observed in Cd0.94Zn0.04Fe0.02S films are the effective way to use solar energy and enhance its photocatalytic activity under visible light. The enhanced green band emission than blue band by Zn-doping evidenced the existence of higher defect states.

  2. Low-Temperature Growth of Well-Aligned ZnO Nanorod Arrays by Chemical Bath Deposition for Schottky Diode Application

    NASA Astrophysics Data System (ADS)

    Yuan, Zhaolin

    2015-04-01

    A well-aligned ZnO nanorod array (ZNRA) was successfully grown on an indium tin oxide (ITO) substrate by chemical bath deposition at low temperature. The morphology, crystalline structure, transmittance spectrum and photoluminescence spectrum of as-grown ZNRA were investigated by field emission scanning electron microscopy, x-ray diffraction, ultraviolet-visible spectroscopy and spectrophotometer, respectively. The results of these measurements showed that the ZNRA contained densely packed, aligned nanorods with diameters from 30 nm to 40 nm and a wurtzite structure. The ZNRA exhibited good optical transparency within the visible spectral range, with >80% transmission. Gold (Au) was deposited on top of the ZNRA, and the current-voltage characteristics of the resulting ITO/ZNRA/Au device in the dark were evaluated in detail. The ITO/ZNRA/Au device acted as a Schottky barrier diode with rectifying behaviour, low turn-on voltage (0.6 V), small reverse-bias saturation current (3.73 × 10-6 A), a high ideality factor (3.75), and a reasonable barrier height (0.65 V) between the ZNRA and Au.

  3. Fabrication and characterization of ZnO nanorods/p-6H-SiC heterojunction LED by microwave-assisted chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Hassan, J. J.; Mahdi, M. A.; Ramizy, Asmiet; Abu Hassan, H.; Hassan, Z.

    2013-01-01

    High-quality vertically aligned zinc oxide nanorods were successfully grown on p-type 6H-SiC substrate by microwave-assisted chemical bath deposition. The novel seed material poly(vinyl alcohol)-Zn(OH)2 nanocomposites was used to seed the 6H-SiC substrate. X-ray diffraction analysis and field emission scanning electron microscopy showed that the synthesized ZnO nanorods were vertically well aligned in the direction of the (0 0 2) plane of the hexagonal structure. The optical properties were examined by photoluminescence spectroscopy, which showed a high-intensity UV peak compared with visible defect peaks. The current-voltage property proved the good rectifier characteristic of the n-type ZnO nanorod/p-type SiC diode heterojunction. The electroluminescence emission of the heterojunction LED was sufficiently high to be seen with the naked eye, with a broad peak centered at the green part of the visible spectrum.

  4. Chemical Bath Deposition of p-Type Transparent, Highly Conducting (CuS)x:(ZnS)1-x Nanocomposite Thin Films and Fabrication of Si Heterojunction Solar Cells.

    PubMed

    Xu, Xiaojie; Bullock, James; Schelhas, Laura T; Stutz, Elias Z; Fonseca, Jose J; Hettick, Mark; Pool, Vanessa L; Tai, Kong Fai; Toney, Michael F; Fang, Xiaosheng; Javey, Ali; Wong, Lydia Helena; Ager, Joel W

    2016-03-01

    P-type transparent conducting films of nanocrystalline (CuS)x:(ZnS)1-x were synthesized by facile and low-cost chemical bath deposition. Wide angle X-ray scattering (WAXS) and high resolution transmission electron microscopy (HRTEM) were used to evaluate the nanocomposite structure, which consists of sub-5 nm crystallites of sphalerite ZnS and covellite CuS. Film transparency can be controlled by tuning the size of the nanocrystallites, which is achieved by adjusting the concentration of the complexing agent during growth; optimal films have optical transmission above 70% in the visible range of the spectrum. The hole conductivity increases with the fraction of the covellite phase and can be as high as 1000 S cm(-1), which is higher than most reported p-type transparent materials and approaches that of n-type transparent materials such as indium tin oxide (ITO) and aluminum doped zinc oxide (AZO) synthesized at a similar temperature. Heterojunction p-(CuS)x:(ZnS)1-x/n-Si solar cells were fabricated with the nanocomposite film serving as a hole-selective contact. Under 1 sun illumination, an open circuit voltage of 535 mV was observed. This value compares favorably to other emerging heterojunction Si solar cells which use a low temperature process to fabricate the contact, such as single-walled carbon nanotube/Si (370-530 mV) and graphene/Si (360-552 mV). PMID:26855162

  5. Effect of band-aligned double absorber layers on photovoltaic characteristics of chemical bath deposited PbS/CdS thin film solar cells

    NASA Astrophysics Data System (ADS)

    Ho Yeon, Deuk; Chandra Mohanty, Bhaskar; Lee, Seung Min; Soo Cho, Yong

    2015-09-01

    Here we report the highest energy conversion efficiency and good stability of PbS thin film-based depleted heterojunction solar cells, not involving PbS quantum dots. The PbS thin films were grown by the low cost chemical bath deposition (CBD) process at relatively low temperatures. Compared to the quantum dot solar cells which require critical and multistep complex procedures for surface passivation, the present approach, leveraging the facile modulation of the optoelectronic properties of the PbS films by the CBD process, offers a simpler route for optimization of PbS-based solar cells. Through an architectural modification, wherein two band-aligned junctions are stacked without any intervening layers, an enhancement of conversion efficiency by as much as 30% from 3.10 to 4.03% facilitated by absorption of a wider range of solar spectrum has been obtained. As an added advantage of the low band gap PbS stacked over a wide gap PbS, the devices show stability over a period of 10 days.

  6. Preparation of highly photocatalytic active CdS/TiO2 nanocomposites by combining chemical bath deposition and microwave-assisted hydrothermal synthesis

    NASA Astrophysics Data System (ADS)

    Li, Li; Wang, Lili; Hu, Tianyu; Zhang, Wenzhi; Zhang, Xiuli; Chen, Xi

    2014-10-01

    CdS/TiO2 nanocomposites were prepared from Cd and Ti (1:1 M ratio) using cetyltrimethylammonium bromide by a two-step chemical bath deposition (CBD) and microwave-assisted hydrothermal synthesis (MAHS) method. A series of nanocomposites with different morphologies and activities were prepared by varying the reaction time in the MAHS (2, 4, and 6 h). The crystal structure, morphology, and surface physicochemical properties of the nanocomposites were characterized by X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N2 adsorption-desorption measurements. The results show that the CdS/TiO2 nanocomposites were composed of anatase TiO2 and hexagonal CdS phases with strong absorption in the visible region. The surface morphologies changed slightly with increasing microwave irradiation time, while the Brunauer-Emmett-Teller surface area increased remarkably. The photocatalytic degradation of methyl orange (MO) was investigated under UV light and simulated sunlight irradiation. The photocatalytic activity of the CdS/TiO2 (6 h) composites prepared by the MAHS method was higher than those of CdS, P25, and other CdS/TiO2 nanocomposites. The CdS/TiO2 (6 h) nanocomposites significantly affected the UV and microwave-assisted photocatalytic degradation of different dyes. To elucidate the photocatalytic reaction mechanism for the CdS/TiO2 nanocomposites, controlled experiments were performed by adding different radical scavengers.

  7. Effect of band-aligned double absorber layers on photovoltaic characteristics of chemical bath deposited PbS/CdS thin film solar cells

    PubMed Central

    Ho Yeon, Deuk; Chandra Mohanty, Bhaskar; Lee, Seung Min; Soo Cho, Yong

    2015-01-01

    Here we report the highest energy conversion efficiency and good stability of PbS thin film-based depleted heterojunction solar cells, not involving PbS quantum dots. The PbS thin films were grown by the low cost chemical bath deposition (CBD) process at relatively low temperatures. Compared to the quantum dot solar cells which require critical and multistep complex procedures for surface passivation, the present approach, leveraging the facile modulation of the optoelectronic properties of the PbS films by the CBD process, offers a simpler route for optimization of PbS-based solar cells. Through an architectural modification, wherein two band-aligned junctions are stacked without any intervening layers, an enhancement of conversion efficiency by as much as 30% from 3.10 to 4.03% facilitated by absorption of a wider range of solar spectrum has been obtained. As an added advantage of the low band gap PbS stacked over a wide gap PbS, the devices show stability over a period of 10 days. PMID:26394761

  8. A highly porous NiO/polyaniline composite film prepared by combining chemical bath deposition and electro-polymerization and its electrochromic performance.

    PubMed

    Xia, X H; Tu, J P; Zhang, J; Wang, X L; Zhang, W K; Huang, H

    2008-11-19

    A highly porous NiO/polyaniline (PANI) composite film was prepared on ITO glass by combining the chemical bath deposition and electro-polymerization methods, successively. The porous NiO film acts as a template for the preferential growth of PANI along NiO flakes, and the NiO/PANI composite film has an intercrossing net-like morphology. The electrochromic performance of the NiO/PANI composite film was investigated in 1 M LiClO(4)+1 mM HClO(4)/propylene carbonate (PC) by means of transmittance, cyclic voltammetry (CV) and chronoamperometry (CA) measurements. The NiO/PANI thin film exhibits a noticeable electrochromism with reversible color changes from transparent yellow to purple and presents quite good transmittance modulation with a variation of transmittance up to 56% at 550 nm. The porous NiO/polyaniline (PANI) composite film also shows good reaction kinetics with fast switching speed, and the response time for oxidation and reduction is 90 and 110 ms, respectively. PMID:21836256

  9. A highly porous NiO/polyaniline composite film prepared by combining chemical bath deposition and electro-polymerization and its electrochromic performance

    NASA Astrophysics Data System (ADS)

    Xia, X. H.; Tu, J. P.; Zhang, J.; Wang, X. L.; Zhang, W. K.; Huang, H.

    2008-11-01

    A highly porous NiO/polyaniline (PANI) composite film was prepared on ITO glass by combining the chemical bath deposition and electro-polymerization methods, successively. The porous NiO film acts as a template for the preferential growth of PANI along NiO flakes, and the NiO/PANI composite film has an intercrossing net-like morphology. The electrochromic performance of the NiO/PANI composite film was investigated in 1 M LiClO4+1 mM HClO4/propylene carbonate (PC) by means of transmittance, cyclic voltammetry (CV) and chronoamperometry (CA) measurements. The NiO/PANI thin film exhibits a noticeable electrochromism with reversible color changes from transparent yellow to purple and presents quite good transmittance modulation with a variation of transmittance up to 56% at 550 nm. The porous NiO/polyaniline (PANI) composite film also shows good reaction kinetics with fast switching speed, and the response time for oxidation and reduction is 90 and 110 ms, respectively.

  10. Effect of deposition variables on properties of CBD ZnS thin films prepared in chemical bath of ZnSO4/SC(NH2)2/Na3C3H5O7/NH4OH

    NASA Astrophysics Data System (ADS)

    Liu, Wei-Long; Yang, Chang-Siao; Hsieh, Shu-Huei; Chen, Wen-Jauh; Fern, Chi-Lon

    2013-01-01

    The CBD ZnS thin films were prepared on substrates of soda lime glass in chemical bath. The effect of deposition variables including zinc sulfate, thiourea, tri-sodium citrate, ammoina water, bath temperature, and deposition time on the properties of CBD ZnS thin films were comprehensively studied. The CBD ZnS thin films were characterized by a field emission scanning electron microscope (FESEM) for the surface and cross section morphologies and thicknesses, an energy dispersive spectrometer equipped in FESEM for the atomic% of Zn and S, an ultraviolet-visible spectrometer (300-800 nm) for the transmittance and energy gap, and an atomic force microscope for the surface roughness. The results showed that the CBD ZnS thin films have a transmittance for ultraviolet-visible rays (300-800 nm) from 70.8 to 87.8%. The CBD ZnS thin films prepared in bath 5 have an energy gap from 3.881 to 3.980 eV. The CBD ZnS thin films prepared in bath 6 have a growth rate from 1.8 to 3.2 nm/min and activation energy of 59.8 kJ/mol for their growth.

  11. Preparation of highly photocatalytic active CdS/TiO{sub 2} nanocomposites by combining chemical bath deposition and microwave-assisted hydrothermal synthesis

    SciTech Connect

    Li, Li; Wang, Lili; Hu, Tianyu; Zhang, Wenzhi; Zhang, Xiuli; Chen, Xi

    2014-10-15

    CdS/TiO{sub 2} nanocomposites were prepared from Cd and Ti (1:1 M ratio) using cetyltrimethylammonium bromide by a two-step chemical bath deposition (CBD) and microwave-assisted hydrothermal synthesis (MAHS) method. A series of nanocomposites with different morphologies and activities were prepared by varying the reaction time in the MAHS (2, 4, and 6 h). The crystal structure, morphology, and surface physicochemical properties of the nanocomposites were characterized by X-ray diffraction, UV–visible diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and N{sub 2} adsorption–desorption measurements. The results show that the CdS/TiO{sub 2} nanocomposites were composed of anatase TiO{sub 2} and hexagonal CdS phases with strong absorption in the visible region. The surface morphologies changed slightly with increasing microwave irradiation time, while the Brunauer–Emmett–Teller surface area increased remarkably. The photocatalytic degradation of methyl orange (MO) was investigated under UV light and simulated sunlight irradiation. The photocatalytic activity of the CdS/TiO{sub 2} (6 h) composites prepared by the MAHS method was higher than those of CdS, P25, and other CdS/TiO{sub 2} nanocomposites. The CdS/TiO{sub 2} (6 h) nanocomposites significantly affected the UV and microwave-assisted photocatalytic degradation of different dyes. To elucidate the photocatalytic reaction mechanism for the CdS/TiO{sub 2} nanocomposites, controlled experiments were performed by adding different radical scavengers. - Graphical abstract: CdS/TiO{sub 2} nanocomposites were prepared using CTAB by CBD combined with MAHS method. In addition, with increasing microwave irradiation time, the morphology of CdS/TiO{sub 2} changed from popcorn-like to wedge-like structure. - Highlights: • The CdS/TiO{sub 2} was prepared by CBD combined with MAHS two-step method under CTAB. • The morphologies of as-samples were different with the time of

  12. Enhancing the photovoltaic performance and stability of QDSSCs using surface reinforced Pt nanostructures with controllable morphology and superior electrocatalysis via cost-effective chemical bath deposition.

    PubMed

    Rao, S Srinivasa; Durga, Ikkurthi Kanaka; Kang, Tae-Su; Kim, Soo-Kyoung; Punnoose, Dinah; Gopi, Chandu V V M; Eswar Reddy, Araveeti; Krishna, T N V; Kim, Hee-Je

    2016-02-28

    To make quantum-dot sensitized solar cells (QDSSCs) competitive, photovoltaic parameters such as the power conversion efficiency (PCE) and fill factor (FF) must become comparable to those of other emerging solar cell technologies. In the present study, a novel strategy has been successfully developed for a highly efficient surface-modified platinum (Pt) counter electrode (CE) with high catalytic activity and long-term stability in a polysulfide redox electrolyte. The reinforcement of the Pt surface was performed using a thin passivating layer of CuS, NiS, or CoS by simple chemical bath deposition techniques. This method was a more efficient method for reducing the electron recombination in QDSSCs. The optimized Pt/CuS CE shows a very low charge transfer resistance of 37.01 Ω, which is an order of magnitude lower than those of bare Pt (86.32 Ω), Pt/NiS (53.83 Ω), and Pt/CoS (73.51 Ω) CEs. Therefore, the Pt/CuS CEs show much greater catalytic activity in the polysulfide redox electrolyte than Pt, Pt/NiS and Pt/CoS CEs. As a result, under one-sun illumination (AM 1.5G, 100 mW cm(-2)), the Pt/CuS CE exhibits a PCE of 4.32%, which is higher than the values of 1.77%, 2.95%, and 3.25% obtained with bare Pt, Pt/CoS, and Pt/NiS CEs, respectively. The performance of the Pt/CuS CE was enhanced by the improved current density, Cu vacancies with increased S composition, and surface morphology, which enable rapid electron transport and lower the electron recombination rate for the polysulfide electrolyte redox couple. Electrochemical impedance spectroscopy and Tafel polarization revealed that the hybrid CEs reduce interfacial recombination and exhibit better electrochemical and photovoltaic performance compared with a bare Pt CE. The Pt/CuS CE also shows superior stability in the polysulfide electrolyte in a working state for over 10 h, resulting in a long-term electrode stability than Pt CE. PMID:26796086

  13. Effect of deposition parameters and strontium doping on characteristics of nanostructured ZnO thin film by chemical bath deposition method

    SciTech Connect

    Sheeba, N. H.; Naduvath, J.; Abraham, A. Philip, R. R.; Weiss, M. P. E-mail: zachary.diener@hope.edu E-mail: deyoung@hope.edu; Diener, Z. J. E-mail: zachary.diener@hope.edu E-mail: deyoung@hope.edu; Remillard, S. K. E-mail: zachary.diener@hope.edu E-mail: deyoung@hope.edu; DeYoung, P. A. E-mail: zachary.diener@hope.edu E-mail: deyoung@hope.edu

    2014-10-15

    Polycrystalline thin films of ZnO and Sr-doped ZnO (ZnO:Sr) on ultrasonically cleaned soda lime glass substrates are synthesized through successive ionic layer adsorption and reaction. The XRD profiles of ZnO and ZnO:Sr films prepared at different number of deposition cycles exhibit hexagonal wurtzite structure with preferred orientation along (002) direction. The crystallites are found to be nano sized, having variation in size with the increase in number of depositions cycles and also with Sr doping. Optical absorbance studies reveal a systematically controllable blueshift in band gap of Sr-doped ZnO films. SEM images indicate enhanced assembling of crystallites to form elongated rods as number of dips increased in Sr doped ZnO. The films are found to be n-type with the Sr doping having little effect on the electrical properties.

  14. Effect of deposition parameters and strontium doping on characteristics of nanostructured ZnO thin film by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Sheeba, N. H.; Naduvath, J.; Abraham, A.; Weiss, M. P.; Diener, Z. J.; Remillard, S. K.; DeYoung, P. A.; Philip, R. R.

    2014-10-01

    Polycrystalline thin films of ZnO and Sr-doped ZnO (ZnO:Sr) on ultrasonically cleaned soda lime glass substrates are synthesized through successive ionic layer adsorption and reaction. The XRD profiles of ZnO and ZnO:Sr films prepared at different number of deposition cycles exhibit hexagonal wurtzite structure with preferred orientation along (002) direction. The crystallites are found to be nano sized, having variation in size with the increase in number of depositions cycles and also with Sr doping. Optical absorbance studies reveal a systematically controllable blueshift in band gap of Sr-doped ZnO films. SEM images indicate enhanced assembling of crystallites to form elongated rods as number of dips increased in Sr doped ZnO. The films are found to be n-type with the Sr doping having little effect on the electrical properties.

  15. Large-scale self-assembled epitaxial growth of highly-ordered three-dimensional micro/nano single-crystalline PbSe pyramid arrays by selective chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Qiu, Jijun; Weng, Binbin; Li, Lin; Li, Xiaomin; Shi, Zhisheng

    2015-05-01

    Highly ordered three-dimensional micro- and nano- PbSe pyramid arrays were synthesized by using selective epitaxial self-assembled chemical bath deposition method. Each pyramid consists of a very sharp (111) tip with six smooth equivalent {100} facets. Every (100) facet forms an angle of about 54.7° with respect to the (111) facet. The structural features including pyramidal size and period could be precisely tailored by pre-patterned Au mask and etching time. Pyramids are self-assembled on the confined positions by the dual functions of one-dimensional and two-dimensional oriented attachment mechanisms along [110] directions on the (111) surface, following the Gibbs-Curie-Wulff minimum energy principle. This method could effectively create large, bottom-up 3D pyramidal surface patterns in a cost-effective and time-saving manner, which has potential applications in infrared photoconductors, solar cells and light emitting enhancement for display, etc.

  16. Chemical bath deposition of ZnO nanowires at near-neutral pH conditions without hexamethylenetetramine (HMTA): understanding the role of HMTA in ZnO nanowire growth.

    PubMed

    McPeak, Kevin M; Le, Thinh P; Britton, Nathan G; Nickolov, Zhorro S; Elabd, Yossef A; Baxter, Jason B

    2011-04-01

    Chemical bath deposition (CBD) is an inexpensive and reproducible method for depositing ZnO nanowire arrays over large areas. The aqueous Zn(NO(3))(2)-hexamethylenetetramine (HMTA) chemistry is one of the most common CBD chemistries for ZnO nanowire synthesis, but some details of the reaction mechanism are still not well-understood. Here, we report the use of in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy to study HMTA adsorption from aqueous solutions onto ZnO nanoparticle films and show that HMTA does not adsorb on ZnO. This result refutes earlier claims that the anisotropic morphology arises from HMTA adsorbing onto and capping the ZnO {10 1 0} faces. We conclude that the role of HMTA in the CBD of ZnO nanowires is only to control the saturation index of ZnO. Furthermore, we demonstrate the first deposition of ZnO nanowire arrays at 90 °C and near-neutral pH conditions without HMTA. Nanowires were grown using the pH buffer 2-(N-morpholino)ethanesulfonic acid (MES) and continuous titratation with KOH to maintain the same pH conditions where growth with HMTA occurs. This semi-batch synthetic method opens many new opportunities to tailor the ZnO morphology and properties by independently controlling temperature and pH. PMID:21361384

  17. Fabrication of ZnO nanorod/p-GaN high-brightness UV LED by microwave-assisted chemical bath deposition with Zn(OH)2-PVA nanocomposites as seed layer

    NASA Astrophysics Data System (ADS)

    Hassan, J. J.; Mahdi, M. A.; Yusof, Y.; Abu-Hassan, H.; Hassan, Z.; Al-Attar, H. A.; Monkman, A. P.

    2013-03-01

    Chemical solution deposition is a low-temperature and possibly the lowest-cost method of growing ZnO nanorods on a GaN substrate. However, most reported methods leave an interface layer between the grown ZnO nanorods and substrate, which can interfere with light emission and extraction. Here we report the growth of high-quality, vertically aligned ZnO nanorods directly on a p-type GaN substrate, with no interface layer, by microwave-assisted chemical bath deposition using a polyvinyl alcohol (PVA)-Zn(OH)2 nanocomposites as the seed layer. X-ray diffraction and field-emission scanning electron microscopy confirmed the high quality of the nanorods in addition to the narrow and high-intensity UV peak of the photoluminescence spectrum. Three different filling insulator materials, poly methyl methacrylate (PMMA), SiO2, and PVA, were used to fabricate n-ZnO nanorod/p-GaN thin film LED structures. The electroluminescence (EL) properties for these three devices showed different emission peaks, which mainly originated from the recombination of free carriers at the two sides of the heterojunction. All devices showed excellent LED performance under forward and reverse bias; the PMMA device showed EL peaks in the UV-blue region, and the SiO2 device displayed EL peaks in the UV and green regions, respectively.

  18. A study on the structural and mechanical properties of nanocrystalline CuS thin films grown by chemical bath deposition technique

    SciTech Connect

    Mukherjee, Nillohit; Sinha, Arijit; Khan, Gobinda Gopal; Chandra, Debraj; Bhaumik, Asim; Mondal, Anup

    2011-01-15

    We report a chemical route for the deposition of nanocrystalline thin films of CuS, using aqueous solutions of Cu(CH{sub 3}COO){sub 2}, SC(NH{sub 2}){sub 2} and N(CH{sub 2}CH{sub 2}OH){sub 3} [triethanolamine, i.e. TEA] in proper concentrations and ratios. The films were structurally characterized using X-ray diffraction technique (XRD), field emission scanning electron microscopy (FESEM) and optical analysis [both photo luminescence (PL) and ultraviolet-visible (UV-vis)]. Optical studies showed a large blue shift in the band gap energy of the films due to quantum confinement effect exerted by the nanocrystals. From both XRD and FESEM analyses, formation of CuS nanocrystals with sizes within 10-15 nm was evident. A study on the mechanical properties was carried out using nanoindentation and nanoscratch techniques, which showed good mechanical stability and high adherence of the films with the bottom substrate. Such study on the mechanical properties of the CuS thin films is being reported here for the first time. Current-voltage (I-V) measurements were also carried out for the films, which showed p-type conductivity.

  19. Bathing

    MedlinePlus

    ... in the tub or shower. • Always check the water temperature before he or she gets in the tub ... to do, step by step. • Make sure the water temperature is comfortable. • Don’t use bath oil. It ...

  20. Effect of Aluminum Doping on the Nanocrystalline ZnS:Al3+ Films Fabricated on Heavily-Doped p-type Si(100) Substrates by Chemical Bath Deposition Method

    NASA Astrophysics Data System (ADS)

    Zhu, He-Jie; Liang, Yan; Gao, Xiao-Yong; Guo, Rui-Fang; Ji, Qiang-Min

    2015-06-01

    Intrinsic ZnS and aluminum-doped nanocrystalline ZnS (ZnS:Al3+) films with zinc-blende structure were fabricated on heavily-doped p-type Si(100) substrates by chemical bath deposition method. Influence of aluminum doping on the microstructure, and photoluminescent and electrical properties of the films, were intensively investigated. The average crystallite size of the films varying in the range of about 9.0 ˜ 35.0 nm initially increases and then decreases with aluminum doping contents, indicating that the crystallization of the films are initially enhanced and then weakened. The incorporation of Al3+ was confirmed from energy dispersive spectrometry and the induced microstrain in the films. Strong and stable visible emission band resulting from the defect-related light emission were observed for the intrinsic ZnS and ZnS:Al3+ films at room temperature. The photoluminescence related to the aluminum can annihilate due to the self-absorption of ZnS:Al3+ when the Al3+ content surpasses certain value. The variation of the resistivity of the films that initially reduces and then increases is mainly caused by the partial substitute for Zn2+ by Al3+ as well as the enhanced crystallization, and by the enhanced crystal boundary scattering, respectively.

  1. Characterization of ZnS thin films synthesized through a non-toxic precursors chemical bath

    SciTech Connect

    Rodríguez, C.A.; Sandoval-Paz, M.G.; Cabello, G.; Flores, M.; Fernández, H.; Carrasco, C.

    2014-12-15

    Highlights: • High quality ZnS thin films have been deposited by chemical bath deposition technique from a non-toxic precursor’s solution. • Nanocrystalline ZnS thin films with large band gap energy were synthesized without using ammonia. • Evidence that the growing of the thin films is carried out by means of hydroxide mechanism was found. • The properties of these ZnS thin films are similar and in some cases better than the corresponding ones produced using toxic precursors such as ammonia. - Abstract: In solar cells, ZnS window layer deposited by chemical bath technique can reach the highest conversion efficiency; however, precursors used in the process normally are materials highly volatile, toxic and harmful to the environment and health (typically ammonia and hydrazine). In this work the characterization of ZnS thin films deposited by chemical bath in a non-toxic alkaline solution is reported. The effect of deposition technique (growth in several times) on the properties of the ZnS thin film was studied. The films exhibited a high percentage of optical transmission (greater than 80%); as the deposition time increased a decreasing in the band gap values from 3.83 eV to 3.71 eV was observed. From chemical analysis, the presence of ZnS and Zn(OH){sub 2} was identified and X-ray diffraction patterns exhibited a clear peak corresponding to ZnS hexagonal phase (1 0 3) plane, which was confirmed by electron diffraction patterns. From morphological studies, compact samples with well-defined particles, low roughness, homogeneous and pinhole-free in the surface were observed. From obtained results, it is evident that deposits of ZnS–CBD using a non-toxic solution are suitable as window layer for TFSC.

  2. Synthesis of CuFeS2 thin films from acidic chemical baths

    NASA Astrophysics Data System (ADS)

    Tonpe, Dipak; Gattu, Ketan; More, Ganesh; Upadhye, Deepak; Mahajan, Sandip; Sharma, Ramphal

    2016-05-01

    The growth of Copper iron sulfide nanocrystalline thin films onto glass substrates has been achieved by chemical bath deposition at acidic values of pH. The deposited thin films were characterized for their optoelectronic properties using Raman, UV-Vis spectroscopy. The Raman analysis confirms the formation of CuFeS2 thin film. The thin film with nanosized crystallites of CuFeS2 showed a bandgap of 0.7eV from UV-vis absorption spectroscopy.

  3. Ammonia free growth of CdS thin films by Chemical Bath Technique

    NASA Astrophysics Data System (ADS)

    Jaber, A.; Alamri, S. N.; Aida, M. S.

    2011-10-01

    CdS thin films were deposited by a chemical bath deposition technique (CBD). The bath solution is composed of CdCl2 (0.1 M) salt as a source for Cd and thiourea (0.1M) as a source of sulphur (S). To avoid the toxicity and volatility of the commonly used ammonia, ethanolamine (ETA ) is used as complexing agent. Films were deposited with different times from 30 to 120 minutes in order to study the films growth mechanism. The solution temperature was fixed at 60°C. The structural and morphological films characterizations were carried by XRD analysis and AFM observations. From the XRD analysis we inferred that obtained CdS films have a pure hexagonal structure with the preferential orientation along the plane (101). The pure hexagonal structure is highly recommended for the realization of CdTe/ CdS or CuInSe/CdS solar cells. The presence of the hexagonal structure and the low growth rate in order of 1nm/min suggest that the growth mechanism is achieved through the ion by ion process. The optical characterization result indicates that the obtained films have a high transparency from 80 to 60 % in the visible range. In conclusion we inferred that CBD ammonia free CdS thin films deposition enables the production of films suitable for photovoltaic applications.

  4. Chemical Safety: Molten Salt Baths Cited as Lab Hazards.

    ERIC Educational Resources Information Center

    Baum, Rudy

    1982-01-01

    Discusses danger of explosions with molten salts baths, commonly used as heat-transfer media. One such explosion involved use of a bath containing 3-lb sodium nitrite and 1-lb potassium thiocyanate. Although most commercially available mixtures for heat transfer contain oxidizers, a reducer (thiocyanate) was included which possibly triggered the…

  5. Influence of coating bath chemistry on the deposition of 3-mercaptopropyl trimethoxysilane films deposited on magnesium alloy.

    PubMed

    Scott, A F; Gray-Munro, J E; Shepherd, J L

    2010-03-15

    Magnesium alloys have a low specific density and a high strength to weight ratio. This makes them sought after light weight construction materials for automotive and aerospace applications. These materials have also recently become of interest for biomedical applications. Unfortunately, the use of magnesium alloys in many applications has been limited due to its high susceptibility to corrosion. One way to improve the corrosion resistance of magnesium alloys is through the deposition of protective coatings. Many of the current pretreatments/coatings available use toxic chemicals such as chromates and hydrofluoric acid. One possible environmentally friendly alternative is organosilane coatings which have been shown to offer significant corrosion protection to both aluminum alloys and steels. Organosilanes are ambifunctional molecules that are capable of covalent bonding to metal hydroxide surfaces. In order for covalent bonding to occur, the organosilane must undergo hydrolysis in the coating bath followed by a condensation reaction with the surface. There are a number of factors that influence the rates of these reactions such as pH and concentration of reactants. These factors can also influence competing reactions in solution such as oligomerization. The rates of hydrolysis and condensation of 3-mercaptopropyltrimethoxy silane in methanol have been analyzed with (1)H NMR and ATR-FTIR. The results indicate that organosilane oligomers begin to form in solution before the molecules are fully hydrolyzed. The organosilane films deposited on magnesium alloy AZ91 at a variety of concentrations and pre-hydrolysis times were characterized with a combination of ATR-FTIR, ellipsometry and SEM/EDS. The results show that both organosilane film thickness and uniformity are affected by the chemistry occurring in the coating bath prior to deposition. PMID:20064643

  6. Chemical vapor deposition growth

    NASA Technical Reports Server (NTRS)

    Ruth, R. P.; Manasevit, H. M.; Kenty, J. L.; Moudy, L. A.; Simpson, W. I.; Yang, J. J.

    1976-01-01

    A chemical vapor deposition (CVD) reactor system with a vertical deposition chamber was used for the growth of Si films on glass, glass-ceramic, and polycrystalline ceramic substrates. Silicon vapor was produced by pyrolysis of SiH4 in a H2 or He carrier gas. Preliminary deposition experiments with two of the available glasses were not encouraging. Moderately encouraging results, however, were obtained with fired polycrystalline alumina substrates, which were used for Si deposition at temperatures above 1,000 C. The surfaces of both the substrates and the films were characterized by X-ray diffraction, reflection electron diffraction, scanning electron microscopy optical microscopy, and surface profilometric techniques. Several experiments were conducted to establish baseline performance data for the reactor system, including temperature distributions on the sample pedestal, effects of carrier gas flow rate on temperature and film thickness, and Si film growth rate as a function of temperature.

  7. Chemical vapor deposition sciences

    SciTech Connect

    1992-12-31

    Chemical vapor deposition (CVD) is a widely used method for depositing thin films of a variety of materials. Applications of CVD range from the fabrication of microelectronic devices to the deposition of protective coatings. New CVD processes are increasingly complex, with stringent requirements that make it more difficult to commercialize them in a timely fashion. However, a clear understanding of the fundamental science underlying a CVD process, as expressed through computer models, can substantially shorten the time required for reactor and process development. Research scientists at Sandia use a wide range of experimental and theoretical techniques for investigating the science of CVD. Experimental tools include optical probes for gas-phase and surface processes, a range of surface analytic techniques, molecular beam methods for gas/surface kinetics, flow visualization techniques and state-of-the-art crystal growth reactors. The theoretical strategy uses a structured approach to describe the coupled gas-phase and gas-surface chemistry, fluid dynamics, heat and mass transfer of a CVD process. The software used to describe chemical reaction mechanisms is easily adapted to codes that model a variety of reactor geometries. Carefully chosen experiments provide critical information on the chemical species, gas temperatures and flows that are necessary for model development and validation. This brochure provides basic information on Sandia`s capabilities in the physical and chemical sciences of CVD and related materials processing technologies. It contains a brief description of the major scientific and technical capabilities of the CVD staff and facilities, and a brief discussion of the approach that the staff uses to advance the scientific understanding of CVD processes.

  8. Chemical vapor deposition growth

    NASA Technical Reports Server (NTRS)

    Ruth, R. P.; Manasevit, H. M.; Kenty, J. L.; Moudy, L. A.; Simpson, W. I.; Yang, J. J.

    1976-01-01

    The chemical vapor deposition (CVD) method for the growth of Si sheet on inexpensive substrate materials is investigated. The objective is to develop CVD techniques for producing large areas of Si sheet on inexpensive substrate materials, with sheet properties suitable for fabricating solar cells meeting the technical goals of the Low Cost Silicon Solar Array Project. Specific areas covered include: (1) modification and test of existing CVD reactor system; (2) identification and/or development of suitable inexpensive substrate materials; (3) experimental investigation of CVD process parameters using various candidate substrate materials; (4) preparation of Si sheet samples for various special studies, including solar cell fabrication; (5) evaluation of the properties of the Si sheet material produced by the CVD process; and (6) fabrication and evaluation of experimental solar cell structures, using standard and near-standard processing techniques.

  9. Chemical vapor deposition growth

    NASA Technical Reports Server (NTRS)

    Ruth, R. P.; Manasevit, H. M.; Campbell, A. G.; Johnson, R. E.; Kenty, J. L.; Moudy, L. A.; Shaw, G. L.; Simpson, W. I.; Yang, J. J.

    1978-01-01

    The objective was to investigate and develop chemical vapor deposition (CVD) techniques for the growth of large areas of Si sheet on inexpensive substrate materials, with resulting sheet properties suitable for fabricating solar cells that would meet the technical goals of the Low Cost Silicon Solar Array Project. The program involved six main technical tasks: (1) modification and test of an existing vertical-chamber CVD reactor system; (2) identification and/or development of suitable inexpensive substrate materials; (3) experimental investigation of CVD process parameters using various candidate substrate materials; (4) preparation of Si sheet samples for various special studies, including solar cell fabrication; (5) evaluation of the properties of the Si sheet material produced by the CVD process; and (6) fabrication and evaluation of experimental solar cell structures, using impurity diffusion and other standard and near-standard processing techniques supplemented late in the program by the in situ CVD growth of n(+)/p/p(+) sheet structures subsequently processed into experimental cells.

  10. Effect of Bath ph on Electroless Ni-P Coating Deposited on Open-Cell Aluminum Foams

    NASA Astrophysics Data System (ADS)

    Liu, Jiaan; Si, Fujian; Li, Dong; Liu, Yan; Cao, Zheng; Wang, Guoyong

    2015-09-01

    Different electroless Ni-P coatings were deposited on open-cell aluminum foams at various bath pH. The effect of bath pH on the morphology, structure, components, phases and corrosion resistance of the Ni-P coating was studied by scanning electron microscopy (SEM), confocal laser scanning microscope (CLSM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), immersion test and electrochemical polarization measurement, respectively. The experimental results show that the bath pH not only changed the reactivity of the bath, but also had a influence on the microstructure and anticorrosive property of electroless Ni-P coating. The high pH bath raises the thickness of Ni-P coating but decreases the content of phosphorus element in the Ni-P coating. The corrosion resistance of the coated aluminum foams increases when the bath pH rises.

  11. Dynamics of surface evolution in semiconductor thin films grown from a chemical bath.

    PubMed

    Gupta, Indu; Mohanty, Bhaskar Chandra

    2016-01-01

    Dynamics of surface evolution in CdS thin films grown by chemical bath deposition technique has been studied from time sequence of atomic force micrographs. Detailed scaling analysis of surface fluctuation in real and Fourier space yielded characteristic exponents αloc = 0.78 ± 0.07, α = 2.20 ± 0.08, αs = 1.49 ± 0.22, β = 0.86 ± 0.05 and βloc = 0.43 ± 0.10, which are very different from those predicted by the local growth models and are not related to any known universality classes. The observed anomalous scaling pattern, characterized by power law scaling dependence of interface width on deposition time differently at local and global scale, with rapid roughening of the growth front has been discussed to arise as a consequence of a nonlocal effect in the form of diffusional instability. PMID:27615367

  12. Structure of as-deposited and heat-treated iron-zinc coatings from chloride bath

    SciTech Connect

    Drewien, C.A.; Goldstein, J.I.; Marder, A.R.

    1993-09-01

    The iron content, phase constitution, and microstructure of electrodeposited iron-zinc alloy (EZA) coatings, deposited from chloride baths, is described for as-deposited and heat-treated conditions of coatings containing bulk iron contents of 6, 8, 10, and 13 w/o. The observed influence of current density upon iron content, which in turn influences the phase constitution and microstructure of the coatings, is reported. The microstructure, composed of non-equilibrium phases that have nanometer grain sizes, is illustrated and described with respect to iron content, crystallography, and morphology. As-deposited {eta} phase coatings undergo transformations through a sequence of metastable phases when heated. The sequence of phase transformations varies with iron content, but the mechanisms of phase transformation from the as-deposited eta phase to the metastable G phase was found to be similar in 6, 8, and 10 w/o Fe coatings. Microstructural, compositional, and crystallographic changes associated with this phase transformation are discussed.

  13. Effect of bath temperature on electrochemical properties of the anodically deposited manganese dioxide

    NASA Astrophysics Data System (ADS)

    Ghaemi, M.; Biglari, Z.; Binder, L.

    The effect of bath temperature on the electrochemical properties of electrolytic manganese dioxide (EMD) was studied. EMD was produced by anodic deposition from acidic aqueous solution of manganese sulfate at different bath temperatures in the range of 60-120°C. At temperatures above the boiling point of water, the electrolysis was carried out in an autoclave. The EMD produced at 120°C was of gamma type, identified by X-ray diffraction (XRD). Furthermore, the materials produced at 115 and 120°C were quality-controlled by cycling a sample as cathode mix in small size RAM-cells and by scanning electron microscopy. The results indicated an increase in cyclic charge/discharge performance and an improvement of crystallization conditions of EMD produced at elevated temperature when compared to data of commercially available γ-MnO 2.

  14. Continuous High-Aligned Polyacrylonitrile Electrospun Nanofibers Yarns via Circular Deposition on Water Bath.

    PubMed

    Bin, Yu; Hao, Yu; Zhu, Meifang; Wang, Hongzhi

    2016-06-01

    A novel strategy for preparing high-aligned continuous Polyacrylonitrile (PAN) electrospun nanofibers yarns is introduced. The yarn is rolled up from circular deposition, which can be changed by controlling the humidity of spinning environment. High-aligned yarn is obtained with the rolling speed of 57 m/min. Very few defects are found in the received yarn. Also the as-spun yarn is drawn in hot water bath to improve its mechanical properties further. The mechanical properties and X-Ray Diffraction (XRD) tests are systematically investigated. The tensile strength of the as-spun yarn rolled with 57 m/min can reach 240 MPa, close to that of as-spun fibers from wet spinning. Furthermore, after drawn of 5 ratios, tensile strength of yarn comes to 580 MPa, which broaden the applied fields of electrospun nanofibers. In addition, the forming mechanism of yarn in the water bath is analyzed and compared with the previous work. Actually, it can be testified experimentally that PAN nanofibers yarn has the same mechanical properties as that prepared with the other approaches with the same testing conditions in this work. The continuous high-aligned electrospun nanofibers PAN yarn via circular deposition in this paper is capable of meeting the requirement of the more applications needing of high mechanical properties and alignment degree. PMID:27427608

  15. Chemical vapor deposition growth

    NASA Technical Reports Server (NTRS)

    Ruth, R. P.; Manasevit, H. M.; Johnson, R. E.; Kenty, J. L.; Moudy, L. A.; Simpson, W. I.; Yang, J. J.

    1976-01-01

    A laboratory type CVD reactor system with a vertical deposition chamber and sample pedestal heated by an external RF coil has been extensively modified by installation of mass flow controllers, automatic process sequence timers, and special bellows-sealed air-operated valves for overall improved performance. Various film characterization procedures, including classical metallography, SEM analyses, X ray diffraction analyses, surface profilometry, and electrical measurements (resistivity, carrier concentration, mobility, spreading resistance profiles, and minority-carrier lifetime by the C-V-t method) area used to correlate Si sheet properties with CVD parameters and substrate properties. Evaluation procedures and measurements are given. Experimental solar cell structures were made both in epitaxial Si sheet (on sapphire substrates) and in polycrystalline material on alumina substrates, the former to provide an indication of what might be an upper limit on performance of the latter. Preliminary results are given, as obtained in cell structures not specially designed to allow for the unique properties of the sheet material, and fabricated in material known to be far from optimum for photovoltaic performance. Low power conversion efficiencies have been obtained in the epitaxial as well as the polycrystalline Si sheet.

  16. Simple Chemical Vapor Deposition Experiment

    ERIC Educational Resources Information Center

    Pedersen, Henrik

    2014-01-01

    Chemical vapor deposition (CVD) is a process commonly used for the synthesis of thin films for several important technological applications, for example, microelectronics, hard coatings, and smart windows. Unfortunately, the complexity and prohibitive cost of CVD equipment makes it seldom available for undergraduate chemistry students. Here, a…

  17. Chemical vapor deposition of sialon

    DOEpatents

    Landingham, R.L.; Casey, A.W.

    A laminated composite and a method for forming the composite by chemical vapor deposition are described. The composite includes a layer of sialon and a material to which the layer is bonded. The method includes the steps of exposing a surface of the material to an ammonia containing atmosphere; heating the surface to at least about 1200/sup 0/C; and impinging a gas containing N/sub 2/, SiCl/sub 4/, and AlCl/sub 3/ on the surface.

  18. Electroless Plating of Palladium on Stainless Steel Substrates in Hydrazine Solutions: A Study of the Relationships Between Bath Parameters, Deposition Mechanisms, and Deposit Morphologies

    NASA Astrophysics Data System (ADS)

    Davis, Stacy

    Development of a reliable and inexpensive method for producing hydrogen permeable membranes is of intense interest to ongoing fuel cell research. This study investigated electroless plating of palladium onto stainless steel substrates in hydrazine solution as a possible means of membrane production. Following initial research to establish the optimum infiltrant particle size, sensitization time, and activation time, electroless plating experiments were performed to determine the effects of varying hydrazine concentration, agitation, and residence time on the palladium deposit quality and morphology. SEM examination of the experimental products elucidated relationships between specific plating bath parameters or combinations of parameters, the governing deposition mechanisms, and the deposit morphologies. The results indicate that it is possible to produce application-specific deposit layer morphologies by modifying the plating bath parameters at critical stages of the plating cycle.

  19. Chemical vapor deposition of sialon

    DOEpatents

    Landingham, Richard L.; Casey, Alton W.

    1982-01-01

    A laminated composite and a method for forming the composite by chemical vapor deposition. The composite includes a layer of sialon and a material to which the layer is bonded. The method includes the steps of exposing a surface of the material to an ammonia containing atmosphere; heating the surface to at least about 1200.degree. C.; and impinging a gas containing in a flowing atmosphere of air N.sub.2, SiCl.sub.4, and AlCl.sub.3 on the surface.

  20. Chemical surface deposition of ultra-thin semiconductors

    DOEpatents

    McCandless, Brian E.; Shafarman, William N.

    2003-03-25

    A chemical surface deposition process for forming an ultra-thin semiconducting film of Group IIB-VIA compounds onto a substrate. This process eliminates particulates formed by homogeneous reactions in bath, dramatically increases the utilization of Group IIB species, and results in the formation of a dense, adherent film for thin film solar cells. The process involves applying a pre-mixed liquid coating composition containing Group IIB and Group VIA ionic species onto a preheated substrate. Heat from the substrate causes a heterogeneous reaction between the Group IIB and VIA ionic species of the liquid coating composition, thus forming a solid reaction product film on the substrate surface.

  1. Nanocrystalline hard chromium electrodeposition from trivalent chromium bath containing carbamide and formic acid: Structure, composition, electrochemical corrosion behavior, hardness and wear characteristics of deposits

    NASA Astrophysics Data System (ADS)

    Danilov, F. I.; Protsenko, V. S.; Gordiienko, V. O.; Kwon, S. C.; Lee, J. Y.; Kim, M.

    2011-07-01

    The paper is devoted to the structure, composition and properties investigations of coatings obtained from a sulfate trivalent chromium bath containing formic acid and carbamide as the complexing agents. The results indicate that the deposits have a nanocrystalline type of structure-there are regions with atomic ordered arrangement in bulk material with the average size of 3-5 nm. Carbon is present as chromium carbide within the coating and it is distributed uniformly inside of the deposit. The deposits under study exhibit particular electrochemical behavior (absence of the active dissolution range in acid solution). The hardness of these coatings does not differ noticeably from that typical of coatings obtained in Cr(VI)-based baths. The wear characteristics of the deposits from the proposed bath are somewhat better than in the case of a common hexavalent chromium bath.

  2. 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.

  3. Chemical vapor deposition of epitaxial silicon

    DOEpatents

    Berkman, Samuel

    1984-01-01

    A single chamber continuous chemical vapor deposition (CVD) reactor is described for depositing continuously on flat substrates, for example, epitaxial layers of semiconductor materials. The single chamber reactor is formed into three separate zones by baffles or tubes carrying chemical source material and a carrier gas in one gas stream and hydrogen gas in the other stream without interaction while the wafers are heated to deposition temperature. Diffusion of the two gas streams on heated wafers effects the epitaxial deposition in the intermediate zone and the wafers are cooled in the final zone by coolant gases. A CVD reactor for batch processing is also described embodying the deposition principles of the continuous reactor.

  4. Flexural strength of acrylic resin repairs processed by different methods: water bath, microwave energy and chemical polymerization

    PubMed Central

    ARIOLI FILHO, João Neudenir; BUTIGNON, Luís Eduardo; PEREIRA, Rodrigo de Paula; LUCAS, Matheus Guilherme; MOLLO JUNIOR, Francisco de Assis

    2011-01-01

    Denture fractures are common in daily practice, causing inconvenience to the patient and to the dentists. Denture repairs should have adequate strength, dimensional stability and color match, and should be easily and quickly performed as well as relatively inexpensive. Objective The aim of this study was to evaluate the flexural strength of acrylic resin repairs processed by different methods: warm water-bath, microwave energy, and chemical polymerization. Material and methods Sixty rectangular specimens (31x10x2.5 mm) were made with warm water-bath acrylic resin (Lucitone 550) and grouped (15 specimens per group) according to the resin type used to make repair procedure: 1) specimens of warm water-bath resin (Lucitone 550) without repair (control group); 2) specimens of warm water-bath resin repaired with warm water-bath; 3) specimens of warm water-bath resin repaired with microwave resin (Acron MC); 4) specimens of warm water-bath resin repaired with autopolymerized acrylic resin (Simplex). Flexural strength was measured with the three-point bending in a universal testing machine (MTS 810 Material Test System) with load cell of 100 kgf under constant speed of 5 mm/min. Data were analyzed statistically by Kruskal-Wallis test (p<0.05). Results The control group showed the best result (156.04±1.82 MPa). Significant differences were found among repaired specimens and the results were decreasing as follows: group 3 (43.02±2.25 MPa), group 2 (36.21±1.20 MPa) and group 4 (6.74±0.85 MPa). Conclusion All repaired specimens demonstrated lower flexural strength than the control group. Repairs with autopolymerized acrylic resin showed the lowest flexural strength. PMID:21625742

  5. Research and Analysis on the Physical and Chemical Properties of Molten Bath with Bottom-Blowing in EAF Steelmaking Process

    NASA Astrophysics Data System (ADS)

    Wei, Guangsheng; Zhu, Rong; Dong, Kai; Ma, Guohong; Cheng, Ting

    2016-06-01

    Bottom-blowing technology is widely adopted in electric arc furnace (EAF) steelmaking to promote the molten bath fluid flow, accelerate the metallurgical reaction, and improve the quality of molten steel. In this study, a water model experiment and a computational fluid dynamics model were established to investigate the effects of bottom-blowing gas flow rate on the fluid flow characteristics in the EAF molten bath. The results show that the interaction among the bottom-blowing gas streams influences the molten bath flow field, and increasing the bottom-blowing gas flow rate can accelerate the fluid flow and decrease the volume of the dead zone. Based on industrial application research, the physical and chemical properties of the molten bath with bottom-blowing were analyzed. Compared with traditional melting conditions without bottom-blowing, bottom-blowing technology demonstrates obvious advantages in promoting the heat transfer and metallurgical reactions in the molten bath. With the bottom-blowing arrangement, the dephosphorization and decarburization rates are accelerated, the contents of FeO and T. Fe in endpoint slag are decreased, and the endpoint carbon-oxygen equilibrium of molten steel is improved.

  6. Laser Induced Chemical Liquid Phase Deposition (LCLD)

    SciTech Connect

    Nanai, Laszlo; Balint, Agneta M.

    2012-08-17

    Laser induced chemical deposition (LCLD) of metals onto different substrates attracts growing attention during the last decade. Deposition of metals onto the surface of dielectrics and semiconductors with help of laser beam allows the creation of conducting metal of very complex architecture even in 3D. In the processes examined the deposition occurs from solutions containing metal ions and reducing agents. The deposition happens in the region of surface irradiated by laser beam (micro reactors). Physics -chemical reactions driven by laser beam will be discussed for different metal-substrate systems. The electrical, optical, mechanical properties of created interfaces will be demonstrated also including some practical-industrial applications.

  7. Modeling the transport of organic chemicals between polyethylene passive samplers and water in finite and infinite bath conditions.

    PubMed

    Tcaciuc, A Patricia; Apell, Jennifer N; Gschwend, Philip M

    2015-12-01

    Understanding the transfer of chemicals between passive samplers and water is essential for their use as monitoring devices of organic contaminants in surface waters. By applying Fick's second law to diffusion through the polymer and an aqueous boundary layer, the authors derived a mathematical model for the uptake of chemicals into a passive sampler from water, in finite and infinite bath conditions. The finite bath model performed well when applied to laboratory observations of sorption into polyethylene (PE) sheets for various chemicals (polycyclic aromatic hydrocarbons, polychlorinated biphenyls [PCBs], and dichlorodiphenyltrichloroethane [DDT]) and at varying turbulence levels. The authors used the infinite bath model to infer fractional equilibration of PCB and DDT analytes in field-deployed PE, and the results were nearly identical to those obtained using the sampling rate model. However, further comparison of the model and the sampling rate model revealed that the exchange of chemicals was inconsistent with the sampling rate model for partially or fully membrane-controlled transfer, which would be expected in turbulent conditions or when targeting compounds with small polymer diffusivities and small partition coefficients (e.g., phenols, some pesticides, and others). The model can be applied to other polymers besides PE as well as other chemicals and in any transfer regime (membrane, mixed, or water boundary layer-controlled). Lastly, the authors illustrate practical applications of this model such as improving passive sampler design and understanding the kinetics of passive dosing experiments. PMID:26109238

  8. Numerical modeling tools for chemical vapor deposition

    NASA Technical Reports Server (NTRS)

    Jasinski, Thomas J.; Childs, Edward P.

    1992-01-01

    Development of general numerical simulation tools for chemical vapor deposition (CVD) was the objective of this study. Physical models of important CVD phenomena were developed and implemented into the commercial computational fluid dynamics software FLUENT. The resulting software can address general geometries as well as the most important phenomena occurring with CVD reactors: fluid flow patterns, temperature and chemical species distribution, gas phase and surface deposition. The physical models are documented which are available and examples are provided of CVD simulation capabilities.

  9. Chemical vapor deposition of mullite coatings

    DOEpatents

    Sarin, Vinod; Mulpuri, Rao

    1998-01-01

    This invention is directed to the creation of crystalline mullite coatings having uniform microstructure by chemical vapor deposition (CVD). The process comprises the steps of establishing a flow of reactants which will yield mullite in a CVD reactor, and depositing a crystalline coating from the reactant flow. The process will yield crystalline coatings which are dense and of uniform thickness.

  10. Occult chemical deposition to a Maritime forest

    SciTech Connect

    Vong, R.J.; Kowalski, A.S.

    1996-12-31

    Studies of chemical fluxes from the atmosphere to vegetated surfaces have suggested that, along with conventional wet and dry processes, an additional chemical input occurs when wind-blown cloud droplets are directly intercepted by vegetation. This cloud water deposition process has been sometimes termed {open_quote}occult deposition{close_quote} because the water fluxes cannot ordinarily be observed using rain gauges. Such occult deposition of cloud water has rarely been measured directly, in part because of the complexity of the governing turbulent transfer process. However, reviews by the National Acidic Precipitation Assessment Program (NAPAP SoS/T-2,6) have suggested that the chemical flux to be forest decline in the eastern USA. This paper presents direct field measurements occult chemical fluxes to a silver fir forest located in complex terrain on the Olympic Peninsula near the coast of Washington State, USA.

  11. Quantitative study on the chemical solution deposition of zinc oxysulfide

    DOE PAGESBeta

    Reinisch, Michael; Perkins, Craig L.; Steirer, K. Xerxes

    2015-11-21

    Zinc Oxysulfide (ZnOS) has demonstrated potential in the last decade to replace CdS as a buffer layer material since it is a wide-band-gap semiconductor with performance advantages over CdS (Eg = 2.4 eV) in the near UV-range for solar energy conversion. However, questions remain on the growth mechanisms of chemical bath deposited ZnOS. In this study, a detailed model is employed to calculate solubility diagrams that describe simple conditions for complex speciation control using only ammonium hydroxide without additional base. For these conditions, ZnOS is deposited via aqueous solution deposition on a quartz crystal microbalance in a continuous flow cell.more » Data is used to analyze the growth rate dependence on temperature and also to elucidate the effects of dimethylsulfoxide (DMSO) when used as a co-solvent. Activation energies (EA) of ZnOS are calculated for different flow rates and solution compositions. As a result, the measured EA relationships are affected by changes in the primary growth mechanism when DMSO is included.« less

  12. Quantitative study on the chemical solution deposition of zinc oxysulfide

    SciTech Connect

    Reinisch, Michael; Perkins, Craig L.; Steirer, K. Xerxes

    2015-11-21

    Zinc Oxysulfide (ZnOS) has demonstrated potential in the last decade to replace CdS as a buffer layer material since it is a wide-band-gap semiconductor with performance advantages over CdS (Eg = 2.4 eV) in the near UV-range for solar energy conversion. However, questions remain on the growth mechanisms of chemical bath deposited ZnOS. In this study, a detailed model is employed to calculate solubility diagrams that describe simple conditions for complex speciation control using only ammonium hydroxide without additional base. For these conditions, ZnOS is deposited via aqueous solution deposition on a quartz crystal microbalance in a continuous flow cell. Data is used to analyze the growth rate dependence on temperature and also to elucidate the effects of dimethylsulfoxide (DMSO) when used as a co-solvent. Activation energies (EA) of ZnOS are calculated for different flow rates and solution compositions. As a result, the measured EA relationships are affected by changes in the primary growth mechanism when DMSO is included.

  13. Chemical-Vapor-Deposited Diamond Film

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa

    1999-01-01

    This chapter describes the nature of clean and contaminated diamond surfaces, Chemical-vapor-deposited (CVD) diamond film deposition technology, analytical techniques and the results of research on CVD diamond films, and the general properties of CVD diamond films. Further, it describes the friction and wear properties of CVD diamond films in the atmosphere, in a controlled nitrogen environment, and in an ultra-high-vacuum environment.

  14. Chemical effect on ozone deposition over seawater

    EPA Science Inventory

    Surface layer resistance plays an important role in determining ozone deposition velocity over seawater. Recent studies suggest that surface layer resistance over sea-water is influenced by wind-speed and chemical interaction at the air-water interface. Here, we investigate the e...

  15. Low-pressure, chemical vapor deposition polysilicon

    NASA Technical Reports Server (NTRS)

    Gallagher, B. D.; Crotty, G. C.

    1986-01-01

    The low-pressure chemical vapor deposition (LPCVD) of polycrystalline silicon was investigted. The physical system was described, as was the controlling process parameters and requirements for producing films for use as an integral portion of the solar cell contact system.

  16. Chemical vapor deposition coating for micromachines

    SciTech Connect

    MANI,SEETHAMBAL S.; FLEMING,JAMES G.; SNIEGOWSKI,JEFFRY J.; DE BOER,MAARTEN P.; IRWIN,LAWRENCE W.; WALRAVEN,JEREMY A.; TANNER,DANELLE M.; DUGGER,MICHAEL T.

    2000-04-21

    Two major problems associated with Si-based MEMS devices are stiction and wear. Surface modifications are needed to reduce both adhesion and friction in micromechanical structures to solve these problems. In this paper, the authors will present a process used to selectively coat MEMS devices with tungsten using a CVD (Chemical Vapor Deposition) process. The selective W deposition process results in a very conformal coating and can potentially solve both stiction and wear problems confronting MEMS processing. The selective deposition of tungsten is accomplished through silicon reduction of WF{sub 6}, which results in a self-limiting reaction. The selective deposition of W only on polysilicon surfaces prevents electrical shorts. Further, the self-limiting nature of this selective W deposition process ensures the consistency necessary for process control. Selective tungsten is deposited after the removal of the sacrificial oxides to minimize process integration problems. This tungsten coating adheres well and is hard and conducting, requirements for device performance. Furthermore, since the deposited tungsten infiltrates under adhered silicon parts and the volume of W deposited is less than the amount of Si consumed, it appears to be possible to release stuck parts that are contacted over small areas such as dimples. Results from tungsten deposition on MEMS structures with dimples will be presented. The effect of wet and vapor phase cleanings prior to the deposition will be discussed along with other process details. The W coating improved wear by orders of magnitude compared to uncoated parts. Tungsten CVD is used in the integrated-circuit industry, which makes this approach manufacturable.

  17. Chemical vapor deposition of group IIIB metals

    DOEpatents

    Erbil, A.

    1989-11-21

    Coatings of Group IIIB metals and compounds thereof are formed by chemical vapor deposition, in which a heat decomposable organometallic compound of the formula given in the patent where M is a Group IIIB metal, such as lanthanum or yttrium and R is a lower alkyl or alkenyl radical containing from 2 to about 6 carbon atoms, with a heated substrate which is above the decomposition temperature of the organometallic compound. The pure metal is obtained when the compound of the formula 1 is the sole heat decomposable compound present and deposition is carried out under nonoxidizing conditions. Intermetallic compounds such as lanthanum telluride can be deposited from a lanthanum compound of formula 1 and a heat decomposable tellurium compound under nonoxidizing conditions.

  18. Chemical vapor deposition of group IIIB metals

    DOEpatents

    Erbil, Ahmet

    1989-01-01

    Coatings of Group IIIB metals and compounds thereof are formed by chemical vapor deposition, in which a heat decomposable organometallic compound of the formula (I) ##STR1## where M is a Group IIIB metal, such as lanthanum or yttrium and R is a lower alkyl or alkenyl radical containing from 2 to about 6 carbon atoms, with a heated substrate which is above the decomposition temperature of the organometallic compound. The pure metal is obtained when the compound of the formula I is the sole heat decomposable compound present and deposition is carried out under nonoxidizing conditions. Intermetallic compounds such as lanthanum telluride can be deposited from a lanthanum compound of formula I and a heat decomposable tellurium compound under nonoxidizing conditions.

  19. Studies on Structural, Morphological and Optical Properties of Chemically Deposited CdS1-xSex Thin Films.

    PubMed

    Deo, Soumya R; Singh, Ajaya K; Deshmukh, Lata; Singh, Narendra Pratap; Aleksandrova, Mariya P

    2016-03-01

    The thin films of CdS1-xSex were successfully deposited over glass substrates by chemical bath deposition technique. Cadmium acetate, thiourea and sodium selenosulfate were used as source materials for Cd(2+), S(2-) and Se(2-) ions, while 2-mercaptoethanol was used as capping agent. The various deposition conditions such as precursor concentration, deposition temperature, pH and deposition time were optimized for the deposition of CdS1-xSex thin films of good quality and the films were annealed at 200° and 300 °C. The structural, morphological, chemical and optical properties were examined by various characterization techniques and discussed in detail. The optical band gap of CdS1-xSex thin film samples were estimated and found in the range from 2.11 to 1.79 eV for as-deposited and annealed thin films. PMID:26634707

  20. Chemical deposition methods using supercritical fluid solutions

    DOEpatents

    Sievers, Robert E.; Hansen, Brian N.

    1990-01-01

    A method for depositing a film of a desired material on a substrate comprises dissolving at least one reagent in a supercritical fluid comprising at least one solvent. Either the reagent is capable of reacting with or is a precursor of a compound capable of reacting with the solvent to form the desired product, or at least one additional reagent is included in the supercritical solution and is capable of reacting with or is a precursor of a compound capable of reacting with the first reagent or with a compound derived from the first reagent to form the desired material. The supercritical solution is expanded to produce a vapor or aerosol and a chemical reaction is induced in the vapor or aerosol so that a film of the desired material resulting from the chemical reaction is deposited on the substrate surface. In an alternate embodiment, the supercritical solution containing at least one reagent is expanded to produce a vapor or aerosol which is then mixed with a gas containing at least one additional reagent. A chemical reaction is induced in the resulting mixture so that a film of the desired material is deposited.

  1. Advanced deposition model for thermal activated chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Cai, Dang

    Thermal Activated Chemical Vapor Deposition (TACVD) is defined as the formation of a stable solid product on a heated substrate surface from chemical reactions and/or dissociation of gaseous reactants in an activated environment. It has become an essential process for producing solid film, bulk material, coating, fibers, powders and monolithic components. Global market of CVD products has reached multi billions dollars for each year. In the recent years CVD process has been extensively used to manufacture semiconductors and other electronic components such as polysilicon, AlN and GaN. Extensive research effort has been directed to improve deposition quality and throughput. To obtain fast and high quality deposition, operational conditions such as temperature, pressure, fluid velocity and species concentration and geometry conditions such as source-substrate distance need to be well controlled in a CVD system. This thesis will focus on design of CVD processes through understanding the transport and reaction phenomena in the growth reactor. Since the in situ monitor is almost impossible for CVD reactor, many industrial resources have been expended to determine the optimum design by semi-empirical methods and trial-and-error procedures. This approach has allowed the achievement of improvements in the deposition sequence, but begins to show its limitations, as this method cannot always fulfill the more and more stringent specifications of the industry. To resolve this problem, numerical simulation is widely used in studying the growth techniques. The difficulty of numerical simulation of TACVD crystal growth process lies in the simulation of gas phase and surface reactions, especially the latter one, due to the fact that very limited kinetic information is available in the open literature. In this thesis, an advanced deposition model was developed to study the multi-component fluid flow, homogeneous gas phase reactions inside the reactor chamber, heterogeneous surface

  2. Physical-chemical conditions of ore deposition

    USGS Publications Warehouse

    Barton, P.B., Jr.

    1981-01-01

    Ore deposits form under a wide range of physical and chemical conditions, but those precipitating from hot, aqueous fluids-i.e. the hydrothermal deposits-form generally below 700??C and at pressures of only 1 or 2 kbar or less. Natural aqueous fluids in rocks may extract metal and sulfur from a variety of rock types or may acquire them as a residual heritage from a crystallizing silicate magma. Ore-forming hydrothermal fluids never appear as hot springs (except in deep, submarine situations) because they boil, mix with surface waters, and cool, thereby losing their ore-bearing ability before reaching the surface. Mineral systems function as chemical buffers and indicators just as buffers and indicators function in a chemical laboratory. By reading the record written in the buffer/indicator assemblages of minerals one can reconstruct many aspects of the former chemical environment. By studying the record of changing conditions one may deduce information regarding the processes functioning to create the succession of chemical environments and the ore deposits they represent. The example of the OH vein at Creede, Colorado, shows a pH buffered by the K-feldspar + muscovite + quartz assemblage and the covariation of S2 and O2 buffered by the assemblage chlorite + pyrite + quartz. Boiling of the ore fluid led to its oxidation to hematite-bearing assemblages and simultaneously produced an intensely altered, sericitic capping over the vein in response to the condensation of vapors bearing acidic components. The solubility of metals as calculated from experimental and theoretical studies of mineral solubility appears too low by at least one or two powers of ten to explain the mineralization at Creede. In contrast to Creede where the mineral stabilities all point to a relatively consistent chemistry, the Mississippi Valley type deposits present a puzzle of conflicting chemical clues that are impossible to reconcile with any single equilibrium situation. Thus we must

  3. Chemical weathering within high mountain depositional structures

    NASA Astrophysics Data System (ADS)

    Emberson, R.; Hovius, N.; Hsieh, M.; Galy, A.

    2013-12-01

    Material eroded from active mountain belts can spend extended periods in depositional structures within the mountain catchments before reaching its final destination. This can be in the form of colluvial fills, debris fans, or alluvial valley fills and terraces. The existence of these landforms is testament to the catastrophic nature of the events that lead to their formation. Sourced by landslides or debris flows, the material that forms them is in many cases either unweathered or incompletely weathered (e.g. Hsieh and Chyi 2010). Due to their porosity and permeability, these deposits likely serve as locations for extensive chemical weathering within bedrock landscapes. Recent studies considering the weathering flux from active mountain belts (e.g. Calmels et al. 2011) have distinguished between shallow and deep groundwater in terms of the contribution to the solute budget from a catchment; in this study we have attempted to more tightly constrain the sources of these groundwater components in the context of the previously mentioned depositional structures. We have collected water samples from a large number of sites within the Chen-you-lan catchment (370 km2) in central west Taiwan to elucidate the location of chemical weathering as well as how the sourcing of weathering products varies depending on the meteorological conditions. Central Taiwan has good attributes for this work considering both the extremely active tectonics and tropical climate, (including extensive cyclonic activity) which stimulate both extensive physical erosion (Dadson et al. 2003) and chemical weathering (Calmels et al. 2011). The Chen-you-lan catchment in particular contains some of the largest alluvial deposits inside the Taiwan mountain belt (Hsieh and Chyi 2010). Our preliminary results suggest that weathering within intramontane deposits may be a significant source of solutes, with the hyporheic systems within mountain rivers of particular import. This input of solutes occurs over

  4. Chemical vapor deposition of copper films

    NASA Astrophysics Data System (ADS)

    Borgharkar, Narendra Shamkant

    We have studied the kinetics of copper chemical vapor deposition (CVD) for interconnect metallization using hydrogen (Hsb2) reduction of the Cu(hfac)sb2 (copper(II) hexafluoroacetylacetonate) precursor. Steady-state deposition rates were measured using a hot-wall microbalance reactor. For base case conditions of 2 Torr Cu(hfac)sb2, 40 Torr Hsb2, and 300sp°C, a growth rate of 0.5 mg cmsp{-2} hrsp{-1} (ca. 10 nm minsp{-1}) is observed. Reaction order experiments suggest that the deposition rate passes through a maximum at partial pressure of 2 Torr of Cu(hfac)sb2. The deposition rate has an overall half-order dependence on Hsb2 partial pressure. A Langmuir-Hinshelwood rate expression is used to describe the observed kinetic dependencies on Cu(hfac)sb2, Hsb2, and H(hfac). Based on the rate expression a mechanism is proposed in which the overall rate is determined by the surface reaction of adsorbed Cu(hfac)sb2 and H species. Additionally, the role of alcohols in enhancing the deposition rate has been investigated. Addition of isopropanol results in a six fold enhancement to yield a deposition rate of 3.3 mg cmsp{-2} hrsp{-1} (ca. 60 nm minsp{-1}) at 5 Torr of isopropanol, 0.4 Torr Cu(hfac)sb2, 40 Torr Hsb2, and 300sp°C. Ethanol and methanol give lower enhancements of 1.75 and 1.1 mg cmsp{-2} hrsp{-1}, respectively. A mechanism based on the ordering of the aqueous pKsba values of the alcohols is proposed to explain the observed results. Lastly, we have built a warm-wall Pedestal reactor apparatus to demonstrate copper CVD on TiN/Si substrates. The apparatus includes a liquid injection system for transport of isopropanol-diluted precursor solutions. At optimized conditions of precursor and substrate pre-treatments, we have deposited uniform films of copper on TiN/Si substrates at an average deposition rate of 3.0 mg cmsp{-2} hrsp{-1} (ca. 60 nm minsp{-1}).

  5. Biocompatibility of chemical-vapour-deposited diamond.

    PubMed

    Tang, L; Tsai, C; Gerberich, W W; Kruckeberg, L; Kania, D R

    1995-04-01

    The biocompatibility of chemical-vapour-deposited (CVD) diamond surfaces has been assessed. Our results indicate that CVD diamond is as biocompatible as titanium (Ti) and 316 stainless steel (SS). First, the amount of adsorbed and 'denatured' fibrinogen on CVD diamond was very close to that of Ti and SS. Second, both in vitro and in vivo there appears to be less cellular adhesion and activation on the surface of CVD diamond surfaces compared to Ti and SS. This evident biocompatibility, coupled with the corrosion resistance and notable mechanical integrity of CVD diamond, suggests that diamond-coated surfaces may be highly desirable in a number of biomedical applications. PMID:7654876

  6. Preventing Chemical-Vapor Deposition In Selected Areas

    NASA Technical Reports Server (NTRS)

    Keeley, Joseph T.; Goela, Jitendra Singh; Pickering, Michael A.; Taylor, Raymond L.

    1991-01-01

    Method for prevention of chemical-vapor deposition of material in selected areas developed. Gas shroud isolates specific area from rest of deposition system. Inert gas flowing from beneath substrate prevents deposition between substrate and outer ring. Method extremely successful in selective deposition of SiC in chemical-vapor-deposition reactor. Used in deposition of SiC mirror blanks in Large Mirror Substrate and Lidar Mirror programs. Critical element in overall chemical-vapor-deposition process for producing large, lightweight mirrors.

  7. Chemically deposited cubic structured CdO thin films: Room temperature

    NASA Astrophysics Data System (ADS)

    Bulakhe, R. N.; Lokhande, C. D.

    2013-06-01

    Cadmium oxide (CdO) thin films have been synthesized using a chemical bath deposition (CBD) method at room temperature. The prepared CdO thin film were annealed and further used for the structural, morphological, UVVIS characterization. The thermo emf study was made with the TEP setup. The structural study showed polycrystalline CdO material. Morphological study reveals the prism like morphology. Optical and thermo emf study showed n-type nature with optical band gap of 2.13 eV.

  8. Synthesis and characterization of chemically deposited CdS thin films without toxic precursors.

    NASA Astrophysics Data System (ADS)

    Fernández-Pérez, A.; Sandoval-Paz, M. G.

    2016-05-01

    Al doped and undoped CdS thin films (CdS:Al) were deposited on glass, copper and bronze substrates by chemical bath deposition technique in an ammonia-free cadmium-sodium citrate system. The structural and optical properties of the CdS films were determined by X-ray diffraction (XRD), scanning electron microscope (SEM), and simultaneous transmission- reflection spectroscopy. It was found that the properties of the films depend on the amount of Al in the growth solutions and deposition time. The increase in Al content in the reaction solution led to a smaller crystallite size and higher energy band gap that varies in the range 2.42 eV - 2.59 eV depending on the Al content.

  9. Chemical Vapor Deposition Of Silicon Carbide

    NASA Technical Reports Server (NTRS)

    Powell, J. Anthony; Larkin, David J.; Matus, Lawrence G.; Petit, Jeremy B.

    1993-01-01

    Large single-crystal SiC boules from which wafers of large area cut now being produced commerically. Availability of wafers opens door for development of SiC semiconductor devices. Recently developed chemical vapor deposition (CVD) process produces thin single-crystal SiC films on SiC wafers. Essential step in sequence of steps used to fabricate semiconductor devices. Further development required for specific devices. Some potential high-temperature applications include sensors and control electronics for advanced turbine engines and automobile engines, power electronics for electromechanical actuators for advanced aircraft and for space power systems, and equipment used in drilling of deep wells. High-frequency applications include communication systems, high-speed computers, and microwave power transistors. High-radiation applications include sensors and controls for nuclear reactors.

  10. The effects of Mg2+, Mn2+, Zn2+, and Al3+ on the nickel deposit during electrowinning from sulfate bath

    NASA Astrophysics Data System (ADS)

    Gogia, S. K.; Das, S. C.

    1988-12-01

    The presence of impurities like Mg2+, Mn2+, Zn2+, and Al3+ during electrowinning of nickel shows several effects. The effects include current efficiency, deposit quality, purity, crystallographic orientation, surface morphology, and polarization behavior. Addition of the impurities did not change the current efficiency significantly but did change the quality and purity of the electrodeposited nickel. Based on the quality of the deposits obtained, the tolerance limits of these impurities in nickel bath were obtained. Although no deviation of nickel structure from fee was observed, the peak height values for different orientations changed with all of the impurities and the values varied with impurity concentration. The surface morphologies of electrodeposited nickel in the presence of impurities also showed changes. The potentiodynamic scan curves for nickel deposition showed deviations in the presence of all the impurities studied. Based on the results, an attempt was made to correlate the various effects.

  11. Characterization of Metalorganic Chemical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Jesser, W. A.

    1998-01-01

    A series of experimental and numerical investigations to develop a more complete understanding of the reactive fluid dynamics of chemical vapor deposition were conducted. In the experimental phases of the effort, a horizontal CVD reactor configuration was used for the growth of InP at UVA and for laser velocimetry measurements of the flow fields in the reactor at LaRC. This horizontal reactor configuration was developed for the growth of III-V semiconductors and has been used by our research group in the past to study the deposition of both GaAs and InP. While the ultimate resolution of many of the heat and mass transport issues will require access to a reduced-gravity environment, the series of groundbased research makes direct contributions to this area while attempting to answer the design questions for future experiments of how low must gravity be reduced and for how long must this gravity level be maintained to make the necessary measurements. It is hoped that the terrestrial experiments will be useful for the design of future microgravity experiments which likely will be designed to employ a core set of measurements for applications in the microgravity environment such as HOLOC, the Fluid Physics/Dynamics Facility, or the Schlieren photography, the Laser Imaging Velocimetry and the Laser Doppler Velocimetry instruments under development for the Advanced Fluids Experiment Module.

  12. Surface chemical deposition of advanced electronic materials

    NASA Astrophysics Data System (ADS)

    Bjelkevig, Cameron

    The focus of this work was to examine the direct plating of Cu on Ru diffusion barriers for use in interconnect technology and the substrate mediated growth of graphene on boron nitride for use in advanced electronic applications. The electrodeposition of Cu on Ru(0001) and polycrystalline substrates (with and without pretreatment in an iodine containing solution) has been studied by cyclic voltammetry (CV), current--time transient measurements (CTT), in situ electrochemical atomic force microscopy (EC-AFM), and X-ray photoelectron spectroscopy (XPS). The EC-AFM data show that at potentials near the OPD/UPD threshold, Cu crystallites exhibit pronounced growth anisotropy, with lateral dimensions greatly exceeding vertical dimensions. XPS measurements confirmed the presence and stability of adsorbed I on the Ru surface following pre-treatment in a KI/H2SO4 solution and following polarization to at least -200 mV vs. Ag/AgCl. CV data of samples pre-reduced in I-containing electrolyte exhibited a narrow Cu deposition peak in the overpotential region and a UPD peak. The kinetics of the electrodeposited Cu films was investigated by CTT measurements and applied to theoretical models of nucleation. The data indicated that a protective I adlayer may be deposited on an airexposed Ru electrode as the oxide surface is electrochemically reduced, and that this layer will inhibit reformation of an oxide during the Cu electroplating process. A novel method for epitaxial graphene growth directly on a dielectric substrate of systematically variable thickness was studied. Mono/multilayers of BN(111) were grown on Ru(0001) by atomic layer deposition (ALD), exhibiting a flat (non-nanomesh) R30(✓3x✓3) structure. BN(111) was used as a template for growth of graphene by chemical vapor deposition (CVD) of C2H4 at 1000 K. Characterization by LEED, Auger, STM/STS and Raman indicate the graphene is in registry with the BN substrate, and exhibits a HOPG-like 0 eV bandgap density

  13. Survival of the faucet snail after chemical disinfection, pH extremes, and heated water bath treatments

    USGS Publications Warehouse

    Mitchell, A.J.; Cole, R.A.

    2008-01-01

    The faucet snail Bithynia tentaculata, a nonindigenous aquatic snail from Eurasia, was introduced into Lake Michigan in 1871 and has spread to the mid-Atlantic states, the Great Lakes region, Montana, and most recently, the Mississippi River. The faucet snail serves as intermediate host for several trematodes that have caused large-scale mortality among water birds, primarily in the Great Lakes region and Montana. It is important to limit the spread of the faucet snail; small fisheries equipment can serve as a method of snail distribution. Treatments with chemical disinfection, pH extremes, and heated water baths were tested to determine their effectiveness as a disinfectant for small fisheries equipment. Two treatments eliminated all test snails: (1) a 24-h exposure to Hydrothol 191 at a concentration of at least 20 mg/L and (2) a treatment with 50??C heated water for 1 min or longer. Faucet snails were highly resistant to ethanol, NaCl, formalin, Lysol, potassium permanganate, copper sulfate, Baquacil, Virkon, household bleach, and pH extremes (as low as 1 and as high as 13).

  14. Effects of Buffer Salt Concentration on the Dominated Deposition Mechanism and Optical Characteristics of Chemically Deposited Cadmium Sulfide Thin Films

    NASA Astrophysics Data System (ADS)

    Kakhaki, Z. Makhdoumi; Youzbashi, A.; Sangpour, P.; Kazemzadeh, A.; Naderi, N.; Bazargan, A. M.

    2016-02-01

    Effects of buffer salt concentration on the rate of deposition, dominated deposition mechanism and subsequently the structural, morphological, and optical properties of cadmium sulfide (CdS) thin films deposited by chemical bath deposition (CBD) on glass substrate were investigated. The precursors were chosen to be cadmium chloride (CdCl2) as the cadmium source, thiourea (CS(NH2)2) as the sulfur source, ammonium nitrate (NH4NO3) as the buffer salt and ammonia as the complexing agent and the pH controller. The influence of the NH4NO3 concentration on the structure, morphology, film uniformity, stoichiometry and optical properties of CdS thin films was also studied by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX) spectroscope, uv-visible and photoluminescence (PL) spectroscopes. The XRD studies revealed that all the deposited films exhibited a (002)h/(111)c preferred orientation. The crystallite size was increased from 20nm to 30nm by the increase of concentration of NH4NO3 from 0.5M to 2.5M. The morphology of CdS thin films were agglomerated spherical particles consisted of smaller particles. The surface of thin films deposited at the NH4NO3 concentration of 0.5M was compact and smooth. The increase of the concentration of NH4NO3 decreased the packing density of the films. The optical band gap was in the range of 2.25-2.4eV, which was decreased by the decrement of packing density. The PL spectra showed two peaks centered at 400nm and 500nm which are attributed to violet and band-to-band emissions, respectively.

  15. The chemical/physical and microbiological characteristics of typical bath and laundry waste waters. [waste water reclamation during manned space flight

    NASA Technical Reports Server (NTRS)

    Hypes, W. D.; Batten, C. E.; Wilkins, J. R.

    1974-01-01

    Chemical/physical and microbiological characteristics are studied of typical bath and laundry waters collected during a 12 day test in which the untreated waste waters were reused for toilet flush. Most significant changes were found for ammonia, color, methylene blue active substances, phosphates, sodium, sulfates, total organic carbon, total solids, and turbidity in comparison with tap water baseline. The mean total number of microorganisms detected in the waste waters ranged from 1 million to 10 to the 7th power cells/m1 and the mean number of possible coliforms ranged from 10 to the 5th power to 1 million. An accumulation of particulates and an objectible odor were detected in the tankage used during the 12 day reuse of the untreated waste waters. The combined bath and laundry waste waters from a family of four provided 91 percent of the toilet flush water for the same family.

  16. Elimination of a pollution associated with chromic acid during the electro-deposition of Cr(III) using appropriate anodic and membrane materials in a double film bath.

    PubMed

    Jiang, Xiaojun; Chen, Wenchao; Xu, Hongbo

    2009-01-01

    A method using trivalent chromium has been used to replace hexavalent chromium for the electro-deposition of chromium. Using a tri-chamber bath system various anodic materials and membranes were evaluated to minimize the production of environmentally and health damaging chromic acid. By measuring the absorbance of Cr(VI) at 640 nm, the results indicate that the use of a titanium plated ruthenium (Ti-Ru) anode produces the least amount of chromic acid byproduct compared to lead-gold alloy and graphite anodes. The concentration of Cr(VI) in the immediate vicinity of the Ti-Ru anode decreased from 0.389 mg/L to 0 during a 40-min deposition period. The use of a Nafion(TM) quaternary cation exchange membrane portioning the buffer and anode selectively prevented Cr(III) from entering the anode compartment whilst allowing the migration of H(+) to maintain overall voltaic continuity. It has been demonstrated that the use of a Ti-Ru anode with a Nafion(TM) membrane can eliminate the production of chromic acid associated with the electro-deposition of chromium plate thereby preventing its health damaging exposure to plant operators and preventing discharge of Cr(VI) into the environment. Addition of a surfactant improved current efficiency by 34.7%. PMID:25084432

  17. Chemical vapor deposition of graphene single crystals.

    PubMed

    Yan, Zheng; Peng, Zhiwei; Tour, James M

    2014-04-15

    As a two-dimensional (2D) sp(2)-bonded carbon allotrope, graphene has attracted enormous interest over the past decade due to its unique properties, such as ultrahigh electron mobility, uniform broadband optical absorption and high tensile strength. In the initial research, graphene was isolated from natural graphite, and limited to small sizes and low yields. Recently developed chemical vapor deposition (CVD) techniques have emerged as an important method for the scalable production of large-size and high-quality graphene for various applications. However, CVD-derived graphene is polycrystalline and demonstrates degraded properties induced by grain boundaries. Thus, the next critical step of graphene growth relies on the synthesis of large graphene single crystals. In this Account, we first discuss graphene grain boundaries and their influence on graphene's properties. Mechanical and electrical behaviors of CVD-derived polycrystalline graphene are greatly reduced when compared to that of exfoliated graphene. We then review four representative pathways of pretreating Cu substrates to make millimeter-sized monolayer graphene grains: electrochemical polishing and high-pressure annealing of Cu substrate, adding of additional Cu enclosures, melting and resolidfying Cu substrates, and oxygen-rich Cu substrates. Due to these pretreatments, the nucleation site density on Cu substrates is greatly reduced, resulting in hexagonal-shaped graphene grains that show increased grain domain size and comparable electrical properties as to exfoliated graphene. Also, the properties of graphene can be engineered by its shape, thickness and spatial structure. Thus, we further discuss recently developed methods of making graphene grains with special spatial structures, including snowflakes, six-lobed flowers, pyramids and hexagonal graphene onion rings. The fundamental growth mechanism and practical applications of these well-shaped graphene structures should be interesting topics and

  18. Chemically deposited CdS by an ammonia-free process for solar cells window layers

    SciTech Connect

    Ochoa-Landin, R.; Sastre-Hernandez, J.; Vigil-Galan, O.; Ramirez-Bon, R.

    2010-02-15

    Chemically deposited CdS window layers were studied on two different transparent conductive substrates, namely indium tin oxide (ITO) and fluorine doped tin oxide (FTO), to determine the influence of their properties on CdS/CdTe solar cells performance. Three types of CdS films obtained from different chemical bath deposition (CBD) processes were studied. The three CBD processes employed sodium citrate as the complexing agent in partial or full substitution of ammonia. The CdS films were studied by X-ray diffraction, optical transmission spectroscopy and atomic force microscopy. CdS/CdTe devices were completed by depositing 3 {mu}m thick CdTe absorbent layers by means of the close-spaced vapor transport technique (CSVT). Evaporated Cu-Au was used as the back contact in all the solar cells. Dark and under illumination J-V characteristic and quantum efficiency measurements were done on the CdS/CdTe devices to determine their conversion efficiency and spectral response. The efficiency of the cells depended on the window layer and on the transparent contact with values between 5.7% and 8.7%. (author)

  19. Chemical vapor deposition of aluminum oxide

    DOEpatents

    Gordon, Roy; Kramer, Keith; Liu, Xinye

    2000-01-01

    An aluminum oxide film is deposited on a heated substrate by CVD from one or more alkylaluminum alkoxide compounds having composition R.sub.n Al.sub.2 (OR').sub.6-n, wherein R and R' are alkyl groups and n is in the range of 1 to 5.

  20. Chemical Vapor Deposition of Silicon from Silane Pyrolysis

    NASA Technical Reports Server (NTRS)

    Praturi, A. K.; Lutwack, R.; Hsu, G.

    1977-01-01

    The four basic elements in the chemical vapor deposition (CVD) of silicon from silane are analytically treated from a kinetic standpoint. These elements are mass transport of silane, pyrolysis of silane, nucleation of silicon, and silicon crystal growth. Rate expressions that describe the various steps involved in the chemical vapor deposition of silicon were derived from elementary principles. Applications of the rate expressions for modeling and simulation of the silicon CVD are discussed.

  1. Chemical vapor deposition for automatic processing of integrated circuits

    NASA Technical Reports Server (NTRS)

    Kennedy, B. W.

    1980-01-01

    Chemical vapor deposition for automatic processing of integrated circuits including the wafer carrier and loading from a receiving air track into automatic furnaces and unloading on to a sending air track is discussed. Passivation using electron beam deposited quartz is also considered.

  2. Synthetic Graphene Grown by Chemical Vapor Deposition on Copper Foils

    NASA Astrophysics Data System (ADS)

    Chung, Ting Fung; Shen, Tian; Cao, Helin; Jauregui, Luis A.; Wu, Wei; Yu, Qingkai; Newell, David; Chen, Yong P.

    2013-04-01

    The discovery of graphene, a single layer of covalently bonded carbon atoms, has attracted intense interest. Initial studies using mechanically exfoliated graphene unveiled its remarkable electronic, mechanical and thermal properties. There has been a growing need and rapid development in large-area deposition of graphene film and its applications. Chemical vapor deposition on copper has emerged as one of the most promising methods in obtaining large-scale graphene films with quality comparable to exfoliated graphene. In this paper, we review the synthesis and characterizations of graphene grown on copper foil substrates by atmospheric pressure chemical vapor deposition. We also discuss potential applications of such large-scale synthetic graphene.

  3. Chemical characterization of combustion deposits by TOF-SIMS

    NASA Astrophysics Data System (ADS)

    Sjövall, P.; Lausmaa, J.; Tullin, C.; Högberg, J.

    2003-01-01

    We have investigated the potential usefulness of TOF-SIMS for chemical analysis of deposits formed in combustion reactors. By using TOF-SIMS, it was possible to (i) identify inorganic chemical compounds in the deposits, (ii) semi-quantitatively estimate the relative concentrations of the main constituents and (iii) obtain images showing the lateral distribution of the main constituents, on the surface and in cross-sections of deposit samples. It was found that the main components in the deposit samples were KCl and K 2SO 4, while K 2CO 3, NaCl, Na 2SO 4, Ca(OH) 2 and CaCl 2 were present in smaller concentrations. In addition, deposits from combustion of recycled wood chips contained considerable amounts of ZnCl 2, PbCl 2, ZnO and PbO. Large variations in the chemical composition were observed for different samples and throughout the cross-section of a single sample. The chlorides, in particular NaCl, were present mainly as particles, while the sulfates were more homogeneously distributed in the deposit. The results from this study show that TOF-SIMS analysis of combustion deposits can contribute significantly to an increased understanding of the formation and growth of deposits in combustion reactors.

  4. Chemical vapor deposition of amorphous semiconductor films. Final subcontract report

    SciTech Connect

    Rocheleau, R.E.

    1984-12-01

    Chemical vapor deposition (CVD) from higher order silanes has been studied for fabricating amorphous hydrogenated silicon thin-film solar cells. Intrinsic and doped a-Si:H films were deposited in a reduced-pressure, tubular-flow reactor, using disilane feed-gas. Conditions for depositing intrinsic films at growth rates up to 10 A/s were identified. Electrical and optical properties, including dark conductivity, photoconductivity, activation energy, optical absorption, band-gap and sub-band-gap absorption properties of CVD intrinsic material were characterized. Parameter space for depositing intrinsic and doped films, suitable for device analysis, was identified.

  5. Chemical Vapor Deposition of Turbine Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Haven, Victor E.

    1999-01-01

    Ceramic thermal barrier coatings extend the operating temperature range of actively cooled gas turbine components, therefore increasing thermal efficiency. Performance and lifetime of existing ceram ic coatings are limited by spallation during heating and cooling cycles. Spallation of the ceramic is a function of its microstructure, which is determined by the deposition method. This research is investigating metalorganic chemical vapor deposition (MOCVD) of yttria stabilized zirconia to improve performance and reduce costs relative to electron beam physical vapor deposition. Coatings are deposited in an induction-heated, low-pressure reactor at 10 microns per hour. The coating's composition, structure, and response to the turbine environment will be characterized.

  6. Light-induced chemical vapour deposition painting with titanium dioxide

    NASA Astrophysics Data System (ADS)

    Halary-Wagner, E.; Bret, T.; Hoffmann, P.

    2003-03-01

    Light-induced chemical vapour deposits of titanium dioxide are obtained from titanium tetra-isopropoxide (TTIP) in an oxygen and nitrogen atmosphere with a long pulse (250 ns) 308 nm XeCl excimer laser using a mask projection set-up. The demonstrated advantages of this technique are: (i) selective area deposition, (ii) precise control of the deposited thickness and (iii) low temperature deposition, enabling to use a wide range of substrates. A revolving mask system enables, in a single reactor load, to deposit shapes of controlled heights, which overlap to build up a complex pattern. Interferential multi-coloured deposits are achieved, and the process limitations (available colours and resolution) are discussed.

  7. Noncyanide cadmium plating baths. Final report

    SciTech Connect

    Pearlstein, F.; Agarwala, V.S.

    1991-10-04

    One approach to minimizing toxic wastes is to eliminate the use of cyanide plating baths. Non-cyanide zinc plating baths have been successfully developed and have found widespread use. An investigation was conducted in an attempt to accomplish similar results with cadmium plating baths. The focus of this study was on additives to a near neutral cadmium bath, free of complexing agents. A Hull cell was used to enable visualization of deposits over a broad range of cathode current densities. Experimental design (Taguchi Method) was used to optimize bath parameters and constituent concentrations. Bath parameters have been developed which indicate promise for producing dense deposits with good covering power, and relatively low tendency for hydrogen embrittlement.

  8. Bubble bath soap poisoning

    MedlinePlus

    ... medlineplus.gov/ency/article/002762.htm Bubble bath soap poisoning To use the sharing features on this page, please enable JavaScript. Bubble bath soap poisoning occurs when someone swallows bubble bath soap. ...

  9. Chemical vapor deposition of boron-doped hydrogenated amorphous silicon

    SciTech Connect

    Ellis F.B. Jr.; Delahoy, A.E.

    1985-07-15

    Deposition conditions and film properties for a variety of boron-doped hydrogenated amorphous silicon films and silicon-carbon films produced by chemical vapor deposition (CVD) are discussed. Deposition gases include monosilane, disilane, trisilane, and acetylene. Two types of optically wide band-gap p layers are obtained. One of these window p layers (without carbon) has been extensively tested in photovoltaic devices. Remarkably, this p layer can be deposited between about 200 to 300 /sup 0/C. A typical open circuit voltage in an all CVD p-i-n device is 0.70--0.72 V, and in a hybrid device where the i and n layers are deposited by glow discharge, 0.8--0.83 V.

  10. Chemical vapor deposition reactor. [providing uniform film thickness

    NASA Technical Reports Server (NTRS)

    Chern, S. S.; Maserjian, J. (Inventor)

    1977-01-01

    An improved chemical vapor deposition reactor is characterized by a vapor deposition chamber configured to substantially eliminate non-uniformities in films deposited on substrates by control of gas flow and removing gas phase reaction materials from the chamber. Uniformity in the thickness of films is produced by having reactive gases injected through multiple jets which are placed at uniformally distributed locations. Gas phase reaction materials are removed through an exhaust chimney which is positioned above the centrally located, heated pad or platform on which substrates are placed. A baffle is situated above the heated platform below the mouth of the chimney to prevent downdraft dispersion and scattering of gas phase reactant materials.

  11. Chemical vapor deposition modeling: An assessment of current status

    NASA Technical Reports Server (NTRS)

    Gokoglu, Suleyman A.

    1991-01-01

    The shortcomings of earlier approaches that assumed thermochemical equilibrium and used chemical vapor deposition (CVD) phase diagrams are pointed out. Significant advancements in predictive capabilities due to recent computational developments, especially those for deposition rates controlled by gas phase mass transport, are demonstrated. The importance of using the proper boundary conditions is stressed, and the availability and reliability of gas phase and surface chemical kinetic information are emphasized as the most limiting factors. Future directions for CVD are proposed on the basis of current needs for efficient and effective progress in CVD process design and optimization.

  12. [Chemical composition of deposits on IUD removed from uterus].

    PubMed

    Liu, T Y

    1984-05-01

    An electroprobe is used to analyze the elements and x-ray diffraction technology to determine the crystal structure of deposits on IUDs removed from the uterus, so that the chemical composition of these deposits may be studied. Deposits on a number of copper or stainless steel IUDs are removed and undergo electroprobe analysis, the results of which are compare dwith the results of calcite analysis done using the same method. Several deposit samples are studied using x-ray diffraction technology. The results of the latter study are compared with the results of the x-ray diffraction studies of calcium carbonate and calcite. Both copper and stainless steel IUDs were found to have the same type of deposits, containing traces of cooper, magnesium, potassium, sodium, iron, sulphur, phosphorus, and chlorine. The x-ray diffraction spectrum for these deposits was found to be the same as those of calcium carbonate and calcite (hexagonal crystal). Deposits on stainless steel and copper IUDs were found to be similar to calcite. With the exception of calcium, the other elements are thought to come from amino acid, which is readily combined with calcium carbonate in the uterus. These findings confirm the fact that IUDs cause the presence of more calcium ions in th uterus. 120 copper IUDs place in the uterus from 1 to 7 years and 156 stainless steel IUDs placed in the uterus from 1 month to 19 years were used. The volume of the deposits was so small that electroprobing was the only method which could accurately determine all the chemical elements these deposits contained. PMID:12313205

  13. Chemical vapor deposition of graphene on copper at reduced temperatures

    NASA Astrophysics Data System (ADS)

    Gallo, Eric M.; Willner, Bruce I.; Hwang, Jeonghyun; Sun, Shangzhu; Spencer, Michael; Salagaj, Tom; Mitchel, William C.; Sbrockey, Nick; Tompa, Gary S.

    2012-09-01

    A preliminary study on reduced temperature chemical vapor deposition of graphene on copper substrates was performed. Graphene's exceptional mechanical strength, very high electrical and thermal conductivity, and stability at atomic layer thicknesses, generates potential for a broad range of applications, from nanodevices to transparent conductor to chemical sensor. Of the techniques demonstrated for graphene formation, chemical vapor deposition is the sole process suitable for manufacturing large area films. While large area film deposition of graphene has been shown on metal substrates, this process has been limited to high temperatures, 900-1000C, which increases the cost of production and limits methods of integrating the graphene with other material structures. In this work, CVD of graphene on copper foil was attempted over a range of temperatures (650 - 950C) on substrates as large as 5 x 15 cm in a horizontal tube reactor. Depositions were performed using both CVD and upstream Plasma-Enhanced CVD (PECVD), and the results are compared for both techniques. Quality of graphene films deposited with and without plasma enhancement was characterized by micro Raman spectroscopy.

  14. Finite-Size Bath in Qubit Thermodynamics

    NASA Astrophysics Data System (ADS)

    Pekola, J. P.; Suomela, S.; Galperin, Y. M.

    2016-09-01

    We discuss a qubit weakly coupled to a finite-size heat bath (calorimeter) from the point of view of quantum thermodynamics. The energy deposited to this environment together with the state of the qubit provides a basis to analyze the heat and work statistics of this closed combined system. We present results on two representative models, where the bath is composed of two-level systems or harmonic oscillators, respectively. Finally, we derive results for an open quantum system composed of the above qubit plus finite-size bath, but now the latter is coupled to a practically infinite bath of the same nature of oscillators or two-level systems.

  15. Finite-Size Bath in Qubit Thermodynamics

    NASA Astrophysics Data System (ADS)

    Pekola, J. P.; Suomela, S.; Galperin, Y. M.

    2016-04-01

    We discuss a qubit weakly coupled to a finite-size heat bath (calorimeter) from the point of view of quantum thermodynamics. The energy deposited to this environment together with the state of the qubit provides a basis to analyze the heat and work statistics of this closed combined system. We present results on two representative models, where the bath is composed of two-level systems or harmonic oscillators, respectively. Finally, we derive results for an open quantum system composed of the above qubit plus finite-size bath, but now the latter is coupled to a practically infinite bath of the same nature of oscillators or two-level systems.

  16. Chemical-vapor deposition of silicon from silane

    NASA Technical Reports Server (NTRS)

    Hsu, G. C.; Lutwack, R.; Praturi, A. K.

    1979-01-01

    Report lists tables of standard free-energy change, equilibrium constant, and heat of reaction for chemical vapor deposition (CVD) of silicon from silane over temperature range of 100 to 1000 K. Data indicates silicon CVD may be a commercially economical process for production of silicon for solar arrays and other applications.

  17. Chemical Vapor Deposition of Aluminum Oxide Thin Films

    ERIC Educational Resources Information Center

    Vohs, Jason K.; Bentz, Amy; Eleamos, Krystal; Poole, John; Fahlman, Bradley D.

    2010-01-01

    Chemical vapor deposition (CVD) is a process routinely used to produce thin films of materials via decomposition of volatile precursor molecules. Unfortunately, the equipment required for a conventional CVD experiment is not practical or affordable for many undergraduate chemistry laboratories, especially at smaller institutions. In an effort to…

  18. A model of silicon carbide chemical vapor deposition

    SciTech Connect

    Allendorf, M.D.; Kee, R.J. )

    1991-03-01

    This paper presents a model describing the interacting gas phase and surface chemistry present during the steady-state chemical vapor deposition (CVD) of silicon carbide (SiC). In this work, the authors treat the case of steady-state deposition of SiC from silane (SiH{sub 4}) and propane (C{sub 3}H{sub 8}) mixtures in hydrogen carrier gas at one atmosphere pressure. Epitaxial deposition is assumed to occur on a pre-existing epitaxial silicon carbide crystal. Pyrolysis of SiH{sub 4} and C{sub 3}H{sub 8} is modeled by 83 elementary gas-phase reactions. A set of 36 reactions of gas- phase species with the surface is used to simulate the deposition process. Rates for the gas/surface reactions were obtained from experimental measurements of sticking coefficients in the literature and theoretical estimates. The authors' results represent the first simulation of a silicon carbide deposition process that includes detailed description of both the gas phase and surface reactions. The chemical reaction mechanism is also combined with a model of a rotating disk reactor (RDR), which is a convenient way to study the interaction of chemical reactions with fluid mechanics. Transport of species from the gas to the surface is accounted for using multicomponent transport properties. Predictions of deposition rates as a function of susceptor temperature, disk rotation rate, and reactant partial pressure are presented. In addition, velocity, temperature, and concentration profiles normal to the heated disk for 41 gas-phase species are determined using reactor conditions typical of epitaxial silicon carbide deposition on silicon substrates.

  19. Chemical vapour deposition of zeolitic imidazolate framework thin films

    NASA Astrophysics Data System (ADS)

    Stassen, Ivo; Styles, Mark; Grenci, Gianluca; Gorp, Hans Van; Vanderlinden, Willem; Feyter, Steven De; Falcaro, Paolo; Vos, Dirk De; Vereecken, Philippe; Ameloot, Rob

    2016-03-01

    Integrating metal-organic frameworks (MOFs) in microelectronics has disruptive potential because of the unique properties of these microporous crystalline materials. Suitable film deposition methods are crucial to leverage MOFs in this field. Conventional solvent-based procedures, typically adapted from powder preparation routes, are incompatible with nanofabrication because of corrosion and contamination risks. We demonstrate a chemical vapour deposition process (MOF-CVD) that enables high-quality films of ZIF-8, a prototypical MOF material, with a uniform and controlled thickness, even on high-aspect-ratio features. Furthermore, we demonstrate how MOF-CVD enables previously inaccessible routes such as lift-off patterning and depositing MOF films on fragile features. The compatibility of MOF-CVD with existing infrastructure, both in research and production facilities, will greatly facilitate MOF integration in microelectronics. MOF-CVD is the first vapour-phase deposition method for any type of microporous crystalline network solid and marks a milestone in processing such materials.

  20. Modified chemical route for deposition of molybdenum disulphide thin films

    SciTech Connect

    Vyas, Akshay N. Sartale, S. D.

    2014-04-24

    Molybdenum disulphide (MoS{sub 2}) thin films were deposited on quartz substrates using a modified chemical route. Sodium molybdate and sodium sulphide were used as precursors for molybdenum and sulphur respectively. The route involves formation of tetrathiomolybdate ions (MoS{sub 4}{sup 2−}) and further reduction by sodium borohydride to form MoS{sub 2}. The deposition was performed at room temperature. The deposited films were annealed in argon atmosphere at 1073 K for 1 hour to improve its crystallinity. The deposited films were characterized using scanning electron microscopy (SEM) for morphology, UV-Vis absorption spectroscopy for optical studies and X-ray diffraction (XRD) for structure determination.

  1. Chemically deposited thin films of sulfides and selenides of antimony and bismuth as solar energy materials

    NASA Astrophysics Data System (ADS)

    Nair, M. T.; Nair, Padmanabhan K.; Garcia, V. M.; Pena, Y.; Arenas, O. L.; Garcia, J. C.; Gomez-Daza, O.

    1997-10-01

    Chemical bath deposition techniques for bismuth sulfide, bismuth selenide, antimony sulfide, and antimony selenide thin films of about 0.20 - 0.25 micrometer thickness are reported. All these materials may be considered as solar absorber films: strong optical absorption edges, with absorption coefficient, (alpha) , greater than 104 cm-1, are located at 1.31 eV for Bi2Se3, 1.33 eV for Bi2S3, 1.8 eV for Sb2S3, and 1.35 eV for Sb2Se3. As deposited, all the films are nearly amorphous. However, well defined crystalline peaks matching bismuthinite (JCPDS 17- 0320), paraguanajuatite (JCPDS 33-0214), and stibnite (JCPDS 6-0474) and antimony selenide (JCPDS 15-0861) for Bi2S3, Bi2Se3, Sb2S3 and Sb2Se3 respectively, are observed when the films are annealed in nitrogen at 300 degrees Celsius. This is accompanied by a substantial modification of the electrical conductivity in the films: from 10-7 (Omega) -1 cm-1 (in as prepared films) to 10 (Omega) -1 cm-1 in the case of bismuth sulfide and selenide films, and enhancement of photosensitivity in the case of antimony sulfide films. The chemical deposition of a CuS/CuxSe film on these Vx- VIy films and subsequent annealing at 300 degrees Celsius for 1 h at 1 torr of nitrogen leads to the formation of p-type films (conductivity of 1 - 100 (Omega) -1 cm-1) of multinary composition. Among these, the formation of Cu3BiS3 (JCPDS 9-0488) and Cu3SbS4 (JCPDS 35- 0581), CuSbS2 (JCPDS 35-0413) have been clearly detected. Solar energy applications of these films are suggested.

  2. Chemical vapor deposition and atomic layer deposition of metal oxide and nitride thin films

    NASA Astrophysics Data System (ADS)

    Barton, Jeffrey Thomas

    Processes for depositing thin films with various electronic, optical, mechanical, and chemical properties are indispensable in many industries today. Of the many deposition methods available, chemical vapor deposition (CVD) has proved over time to be one of the most flexible, efficient, and cost-effective. Atomic layer deposition (ALD) is a newer process that is gaining favor as a method for depositing films with excellent properties and unparalleled precision. This work describes the development of novel CVD and ALD processes to deposit a variety of materials. Hafnium oxide and zirconium oxide show promise as replacements for SiO 2 as gate dielectrics in future-generation transistors. These high-k materials would provide sufficient capacitance with layers thick enough to avoid leakage from tunneling. An ALD method is presented here for depositing conformal hafnium oxide from tetrakis-(diethylamido)hafnium and oxygen gas. A CVD method for depositing zirconium oxide from tetrakis-(dialkylamido)zirconium and either oxygen gas or water vapor is also described. The use of copper for interconnects in integrated circuits requires improved diffusion barrier materials, given its high diffusivity compared to the previously-used aluminum and tungsten. Tungsten nitride has a low resistivity among barrier materials, and can be deposited in amorphous films that are effective diffusion barriers in layers as thin as a few nanometers. Here we demonstrate CVD and plasma-enhanced CVD methods to deposit tungsten nitride films from bis-(dialkylamido)bis-( tert-butylimido)tungsten precursors and ammonia gas. Recent findings had shown uniform copper growth on tantalum silicate films, without the dewetting that usually occurs on oxide surfaces. Tantalum and tungsten silicates were deposited by a CVD reaction from the reaction of either tris-(diethylamido)ethylimido tantalum or bis-(ethylmethylamido)-bis-( tert-butylimido)tungsten with tris-(tert-butoxy)silanol. The ability of evaporated

  3. Fundamental studies of chemical vapor deposition diamond growth processes

    SciTech Connect

    Shaw, R.W.; Whitten, W.B.; Ramsey, J.M.; Heatherly, L.

    1991-01-01

    We are developing laser spectroscopic techniques to foster a fundamental understanding of diamond film growth by hot filament chemical vapor deposition (CVD). Several spectroscopic techniques are under investigation to identify intermediate species present in the bulk reactor volume, the thin active volume immediately above the growing film, and the actual growing surface. Such a comprehensive examination of the overall deposition process is necessary because a combination of gas phase and surface chemistry is probably operating. Resonantly enhanced multiphoton ionization (REMPI) techniques have been emphasized. A growth rector that permits through-the-substrate gas sampling for REMPI/time-of-flight mass spectroscopy has been developed. 7 refs., 2 figs.

  4. Combustion chemical vapor deposited coatings for thermal barrier coating systems

    SciTech Connect

    Hampikian, J.M.; Carter, W.B.

    1995-12-31

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings. In this report, the evaluation of alumina and ceria coatings on a nickel-chromium alloy is described.

  5. Chemical and Magnetic Order in Vapor-Deposited Metal Films

    NASA Astrophysics Data System (ADS)

    Rooney, Peter Wiliam

    1995-01-01

    A stochastic Monte Carlo model of vapor deposition and growth of a crystalline, binary, A_3 B metallic alloy with a negative energy of mixing has been developed which incorporates deposition and surface diffusion in a physically correct manner and allows the simulation of deposition rates that are experimentally realizable. The effects of deposition rate and growth temperature on the development of short range order (SRO) in vapor-deposited films have been examined using this model. SRO in the simulated films increases with growth temperature up to the point at which the temperature corresponds to the energy of mixing, but we see no corresponding development of anisotropic SRO (preferential ordering of A-B pairs along the growth direction). Epitaxial (100) and (111) CoPt_3 films have been deposited over a range of growth temperatures from -50^circ C to 800^circC. Curie temperature (T_{rm c}) and saturation magnetization are dramatically enhanced in those films grown near 400^circ C over the values expected for the chemically homogeneous alloy. Magnetization data indicates that the high T _{rm c} films are inhomogeneous. These phenomena are interpreted as evidence of a previously unobserved magnetically driven miscibility gap in the Co-Pt phase diagram. Films grown near 400^circ C exhibit large uniaxial perpendicular magnetic anisotropy that cannot be accounted for by strain. The observed anisotropy coincides with the chemical phase separation and it seems likely that these two phenomena are related. Long range order (LRO) in the as-deposited films peaks at a growth temperature of 630^circC and then decreases with decreasing growth temperature. The decrease in LRO is either due to kinetic frustration or to competition from magnetically induced Co clustering. Theoretical phase diagrams based on the appropriate Blume-Emery-Griffiths Hamiltonian suggest the latter.

  6. Development and study of chemical vapor deposited tantalum base alloys

    NASA Technical Reports Server (NTRS)

    Meier, G. H.; Bryant, W. A.

    1976-01-01

    A technique for the chemical vapor deposition of alloys was developed. The process, termed pulsing, involves the periodic injection of reactant gases into a previously-evacuated reaction chamber where they blanket the substrate almost instantaneously. Formation of alternating layers of the alloy components and subsequent homogenization allows the formation of an alloy of uniform composition with the composition being determined by the duration and relative numbers of the various cycles. The technique has been utilized to produce dense alloys of uniform thickness and composition (Ta- 10 wt % W) by depositing alternating layers of Ta and W by the hydrogen reduction of TaCl5 and WCl6. A similar attempt to deposit a Ta - 8 wt % W - 2 wt% Hf alloy was unsuccessful because of the difficulty in reducing HfCl4 at temperatures below those at which gas phase nucleation of Ta and W occurred.

  7. Chemical vapor deposition of hydrogenated amorphous silicon from disilane

    SciTech Connect

    Bogaert, R.J.; Russell, T.W.F.; Klein, M.T. . Dept. of Chemical Engineering); Rocheleau, R.E.; Baron, B.N. . Inst. of Energy Conversion)

    1989-10-01

    The authors describe hydrogenated amorphous silicon (a-Si:H) thin films deposited at growth rates of 1 to 30 A/s by chemical vapor deposition (CVD) from disilane source gas at 24 torr total pressure in a tubular reactor. The effects of substrate temperature and gas holding time (flow rate) on film growth rate and effluent gas composition were measured at temperatures ranging from 360{sup 0} to 485{sup 0}C and gas holding times from 3 to 62s. Effluent gases determined by gas chromatography included silane, disilane and other higher order silanes. A chemical reaction engineering model, based on a silylene (SiH/sub 2/) insertion gas phase reaction network and film growth from both SiH/sub 2/ and high molecular weight silicon species, Si/sub n/H/sub 2n/, was developed. The model predictions were in good agreement with experimentally determined growth rates and effluent gas compositions.

  8. CHEMICAL SOLUTION DEPOSITION BASED OXIDE BUFFERS AND YBCO COATED CONDUCTORS

    SciTech Connect

    Paranthaman, Mariappan Parans

    2011-01-01

    We have reviewed briefly the growth of buffer and high temperature superconducting oxide thin films using a chemical solution deposition (CSD) method. In the Rolling-Assisted Biaxially Textured Substrates (RABiTS) process, developed at Oak Ridge National Laboratory, utilizes the thermo mechanical processing to obtain the flexible, biaxially oriented copper, nickel or nickel-alloy substrates. Buffers and Rare Earth Barium Copper Oxide (REBCO) superconductors have been deposited epitaxially on the textured nickel alloy substrates. The starting substrate serves as a template for the REBCO layer, which has substantially fewer weak links. Buffer layers play a major role in fabricating the second generation REBCO wire technology. The main purpose of the buffer layers is to provide a smooth, continuous and chemically inert surface for the growth of the REBCO film, while transferring the texture from the substrate to the superconductor layer. To achieve this, the buffer layers need to be epitaxial to the substrate, i.e. they have to nucleate and grow in the same bi-axial texture provided by the textured metal foil. The most commonly used RABiTS multi-layer architectures consist of a starting template of biaxially textured Ni-5 at.% W (Ni-W) substrate with a seed (first) layer of Yttrium Oxide (Y2O3), a barrier (second) layer of Yttria Stabilized Zirconia (YSZ), and a Cerium Oxide (CeO2) cap (third) layer. These three buffer layers are generally deposited using physical vapor deposition (PVD) techniques such as reactive sputtering. On top of the PVD template, REBCO film is then grown by a chemical solution deposition. This article reviews in detail about the list of oxide buffers and superconductor REBCO films grown epitaxially on single crystal and/or biaxially textured Ni-W substrates using a CSD method.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  10. Chemical vapor deposition coating of fibers using microwave application

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B. (Inventor); Hoover, Gordon (Inventor); Jackson, Henry W. (Inventor)

    2000-01-01

    Chemical vapor deposition coating is carried out in a cylindrical cavity. The fibers are heated by a microwave source that is uses a TM0N0 mode, where O is an integer, and produces a field that depends substantially only on radius. The fibers are observed to determine their heating, and their position can be adjusted. Once the fibers are uniformly heated, a CVD reagent is added to process the fibers.

  11. Chemical vapor deposition (CVD) of cubic silicon carbide. Patent Application

    SciTech Connect

    Addamiano, A.

    1985-07-02

    This invention relates to the growth of cubic silicon carbide crystals. More specifically, this invention relates to the growth of cubic silicon carbide by Chemical Vapor Deposition (CVD). One object of the present invention is to provide a novel method for the production of cubic SiC for high temperature electronic devices. Another object of the present invention is to provide a novel method for the production of highly pure, single crystal cubic SiC that is duplicable. Another object of the present invention is to provide a novel method for the production of large-area single-crystal wafers of cubic SiC. These and other objects of the present invention can be achieved by a method for chemical vapor deposition (CVD) of cubic Silicon Carbide (SiC) comprising the steps of etching silicon substrated having one mechanically polished face; depositing a thin buffer layer of cubic SiC formed by reaction between a heated Si substrate and a H2-C3H8 gas mixuture; and depositing SiC on the buffer layer at high temperature using H2+C3HY+SiH4 mixture.

  12. Research on chemical vapor deposition processes for advanced ceramic coatings

    NASA Technical Reports Server (NTRS)

    Rosner, Daniel E.

    1993-01-01

    Our interdisciplinary background and fundamentally-oriented studies of the laws governing multi-component chemical vapor deposition (VD), particle deposition (PD), and their interactions, put the Yale University HTCRE Laboratory in a unique position to significantly advance the 'state-of-the-art' of chemical vapor deposition (CVD) R&D. With NASA-Lewis RC financial support, we initiated a program in March of 1988 that has led to the advances described in this report (Section 2) in predicting chemical vapor transport in high temperature systems relevant to the fabrication of refractory ceramic coatings for turbine engine components. This Final Report covers our principal results and activities for the total NASA grant of $190,000. over the 4.67 year period: 1 March 1988-1 November 1992. Since our methods and the technical details are contained in the publications listed (9 Abstracts are given as Appendices) our emphasis here is on broad conclusions/implications and administrative data, including personnel, talks, interactions with industry, and some known applications of our work.

  13. Modeling and Simulation of Plasma Enhanced Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Smith, Aaron; Bett, Dominic; Cunningham, Monisha; Sen, Sudip

    2015-04-01

    Plasma Enhanced Chemical Vapor Deposition (PECVD) is a process used to deposit thin films from a gas state (vapor) to a solid state on a substrate. Recent study from the X-ray diffraction spectra of SnO2 films deposited as a function of RF power apparently indicates that RF power is playing a stabilizing role and hence in the better deposition. The results show that the RF power results in smoother morphology, improved crystallinity, and lower sheet resistance value in the PECVD process. The PECVD processing allows deposition at lower temperatures, which is often critical in the manufacture of semiconductors. In this talk we will address two aspects of the problem, first to develop a model to study the mechanism of how the PECVD is effected by the RF power, and second to actually simulate the effect of RF power on PECVD. As the PECVD is a very important component of the plasma processing technology with many applications in the semiconductor technology and surface science, the research proposed here has the prospect to revolutionize the plasma processing technology through the stabilizing role of the RF power.

  14. What Are Bath Salts?

    MedlinePlus

    ... Are bath salts becoming more popular? Marsha Lopez Hi, Lauren. Nope! Actually quite the opposite! This family ... and how dangerous for your body? Michelle Rankin Hi ParkerPanella - Bath salts are drugs known as synthetic ...

  15. Chemical etching and organometallic chemical vapor deposition on varied geometries of GaAs

    NASA Technical Reports Server (NTRS)

    Bailey, Sheila G.; Landis, Geoffrey A.; Wilt, David M.

    1989-01-01

    Results of micron-spaced geometries produced by wet chemical etching and subsequent OMCVD growth on various GaAs surfaces are presented. The polar lattice increases the complexity of the process. The slow-etch planes defined by anisotropic etching are not always the same as the growth facets produced during MOCVD deposition, especially for deposition on higher-order planes produced by the hex groove etching.

  16. METAL COATING BATHS

    DOEpatents

    Robinson, J.W.

    1958-08-26

    A method is presented for restoring the effectiveness of bronze coating baths used for hot dip coating of uranium. Such baths, containing a high proportion of copper, lose their ability to wet uranium surfaces after a period of use. The ability of such a bath to wet uranium can be restored by adding a small amount of metallic aluminum to the bath, and skimming the resultant hard alloy from the surface.

  17. Mechanical and piezoresistive properties of thin silicon films deposited by plasma-enhanced chemical vapor deposition and hot-wire chemical vapor deposition at low substrate temperatures

    NASA Astrophysics Data System (ADS)

    Gaspar, J.; Gualdino, A.; Lemke, B.; Paul, O.; Chu, V.; Conde, J. P.

    2012-07-01

    This paper reports on the mechanical and piezoresistance characterization of hydrogenated amorphous and nanocrystalline silicon thin films deposited by hot-wire chemical vapor deposition (HWCVD) and radio-frequency plasma-enhanced chemical vapor deposition (PECVD) using substrate temperatures between 100 and 250 °C. The microtensile technique is used to determine film properties such as Young's modulus, fracture strength and Weibull parameters, and linear and quadratic piezoresistance coefficients obtained at large applied stresses. The 95%-confidence interval for the elastic constant of the films characterized, 85.9 ± 0.3 GPa, does not depend significantly on the deposition method or on film structure. In contrast, mean fracture strength values range between 256 ± 8 MPa and 600 ± 32 MPa: nanocrystalline layers are slightly stronger than their amorphous counterparts and a pronounced increase in strength is observed for films deposited using HWCVD when compared to those grown by PECVD. Extracted Weibull moduli are below 10. In terms of piezoresistance, n-doped radio-frequency nanocrystalline silicon films deposited at 250 °C present longitudinal piezoresistive coefficients as large as -(2.57 ± 0.03) × 10-10 Pa-1 with marginally nonlinear response. Such values approach those of crystalline silicon and of polysilicon layers deposited at much higher temperatures.

  18. Modeling of InP metalorganic chemical vapor deposition

    NASA Technical Reports Server (NTRS)

    Black, Linda R.; Clark, Ivan O.; Kui, J.; Jesser, William A.

    1991-01-01

    The growth of InP by metalorganic chemical vapor deposition (MOCVD) in a horizontal reactor is being modeled with a commercially available computational fluid dynamics modeling code. The mathematical treatment of the MOCVD process has four primary areas of concern: 1) transport phenomena, 2) chemistry, 3) boundary conditions, and 4) numerical solution methods. The transport processes involved in CVD are described by conservation of total mass, momentum, energy, and atomic species. Momentum conservation is described by a generalized form of the Navier-Stokes equation for a Newtonian fluid and laminar flow. The effect of Soret diffusion on the transport of particular chemical species and on the predicted deposition rate is examined. Both gas-phase and surface chemical reactions are employed in the model. Boundary conditions are specified at the inlet and walls of the reactor for temperature, fluid flow and chemical species. The coupled set of equations described above is solved by a finite difference method over a nonuniform rectilinear grid in both two and three dimensions. The results of the 2-D computational model is presented for gravity levels of zero- and one-g. The predicted growth rates at one-g are compared to measured growth rates on fused silica substrates.

  19. Passivation properties of aluminum oxide films deposited by mist chemical vapor deposition for solar cell applications

    NASA Astrophysics Data System (ADS)

    Miki, Shohei; Iguchi, Koji; Kitano, Sho; Hayakashi, Koki; Hotta, Yasushi; Yoshida, Haruhiko; Ogura, Atsushi; Satoh, Shin-ichi; Arafune, Koji

    2015-08-01

    Aluminum oxide (AlOx) films were deposited by mist chemical vapor deposition (MCVD) in air for p-type crystalline silicon, and the effects of the deposition temperature (Tdep) and AlOx film thickness on the maximum surface recombination velocities (Smax) were evaluated. It was found that Smax was improved with increasing Tdep. The AlOx film deposited at 400 °C exhibited the best Smax value of 2.8 cm/s, and the passivation quality was comparable to that of AlOx deposited by other vacuum-based techniques. Smax was also improved with increasing film thickness. When the film thickness was above 10 nm, Smax was approximately 10 cm/s. From the Fourier transform infrared spectra, it was found that the AlOx films deposited by MCVD consisted of an AlOx layer and a Si-diffused AlOx layer. In addition, it is important for the layers to be thick enough to obtain high-quality passivation.

  20. Chemical vapor deposition modeling for high temperature materials

    NASA Technical Reports Server (NTRS)

    Gokoglu, Suleyman A.

    1992-01-01

    The formalism for the accurate modeling of chemical vapor deposition (CVD) processes has matured based on the well established principles of transport phenomena and chemical kinetics in the gas phase and on surfaces. The utility and limitations of such models are discussed in practical applications for high temperature structural materials. Attention is drawn to the complexities and uncertainties in chemical kinetics. Traditional approaches based on only equilibrium thermochemistry and/or transport phenomena are defended as useful tools, within their validity, for engineering purposes. The role of modeling is discussed within the context of establishing the link between CVD process parameters and material microstructures/properties. It is argued that CVD modeling is an essential part of designing CVD equipment and controlling/optimizing CVD processes for the production and/or coating of high performance structural materials.

  1. Further Experimental Investigation of Freeze-Lining/Bath Interface at Steady-State Conditions

    NASA Astrophysics Data System (ADS)

    Fallah-Mehrjardi, Ata; Hayes, Peter; Jak, Evgueni

    2014-12-01

    In design of the freeze-lining deposits in high-temperature reaction systems, it has been widely assumed that the interface temperature between the deposit and bath at steady-state conditions, that is, when the deposit interface velocity is zero, is the liquidus of the bulk bath material. Current work provides conclusive evidence that the interface temperature can be lower than that of the bulk liquidus. The observations are consistent with a mechanism involving the nucleation and growth of solids on detached crystals in a subliquidus layer as this fluid material moves toward the stagnant deposit interface and the dissolution of these detached crystals as they are transported away from the interface by turbulent eddies. The temperature and position of the stable deposit/liquid interface are determined by the balance between the extent of crystallization on the detached crystals and mass transfer across the subliquidus layer from the bulk bath. A conceptual framework is developed to analyze the factors influencing the steady-state deposit/interface temperature and deposit thickness in chemical systems operating in a positive temperature gradient. The framework can be used to explain the experimental observations in a diverse range of chemical systems and conditions, including high-temperature melts and aqueous solutions, and to explain why the interface temperature under these conditions can be between T liquidus and T solidus.

  2. Aerosol chemical vapor deposition of metal oxide films

    DOEpatents

    Ott, Kevin C.; Kodas, Toivo T.

    1994-01-01

    A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

  3. Deposition of thermal and hot-wire chemical vapor deposition copper thin films on patterned substrates.

    PubMed

    Papadimitropoulos, G; Davazoglou, D

    2011-09-01

    In this work we study the hot-wire chemical vapor deposition (HWCVD) of copper films on blanket and patterned substrates at high filament temperatures. A vertical chemical vapor deposition reactor was used in which the chemical reactions were assisted by a tungsten filament heated at 650 degrees C. Hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (CupraSelect) vapors were used, directly injected into the reactor with the aid of a liquid injection system using N2 as carrier gas. Copper thin films grown also by thermal and hot-wire CVD. The substrates used were oxidized silicon wafers on which trenches with dimensions of the order of 500 nm were formed and subsequently covered with LPCVD W. HWCVD copper thin films grown at filament temperature of 650 degrees C showed higher growth rates compared to the thermally ones. They also exhibited higher resistivities than thermal and HWCVD films grown at lower filament temperatures. Thermally grown Cu films have very uniform deposition leading to full coverage of the patterned substrates while the HWCVD films exhibited a tendency to vertical growth, thereby creating gaps and incomplete step coverage. PMID:22097561

  4. Textures and morphologies of chemical vapor deposited (CVD) diamond

    SciTech Connect

    Clausing, R.E.; Heatherly, L.; Horton, L.L.; Specht, E.D.; Begun, G.M. ); Wang, Z.L. )

    1991-01-01

    The textures, surface morphologies, structural perfection, and properties of diamond films grown by activated chemical vapor deposition (CVD) vary greatly with the growth conditions. The evolution of two commonly observed polycrystalline morphologies, which give rise to <110> textures, will be described as well as the development of four films grown to produce <100>, <111>, and near <100>'' textures with various combinations of growth facets. These films were grown to test models of texture development. Films free of twins, microtwins, and stacking faults are deposited when only (100) facets are permitted to grow. In polycrystalline materials, special conditions must be met to avoid the formation of planar defects at the peripheries of individual crystallites. The planar defects grow from (111) or mixed microfaceted surfaces. Twinning plays an important role in growth of (111) faceted surfaces. The films have been characterized with Raman spectroscopy, x-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and optical methods. 13 refs., 7 figs.

  5. Chemical vapor deposition of low reflective cobalt (II) oxide films

    NASA Astrophysics Data System (ADS)

    Amin-Chalhoub, Eliane; Duguet, Thomas; Samélor, Diane; Debieu, Olivier; Ungureanu, Elisabeta; Vahlas, Constantin

    2016-01-01

    Low reflective CoO coatings are processed by chemical vapor deposition from Co2(CO)8 at temperatures between 120 °C and 190 °C without additional oxygen source. The optical reflectivity in the visible and near infrared regions stems from 2 to 35% depending on deposition temperature. The combination of specific microstructural features of the coatings, namely a fractal "cauliflower" morphology and a grain size distribution more or less covering the near UV and IR wavelength ranges enhance light scattering and gives rise to a low reflectivity. In addition, the columnar morphology results in a density gradient in the vertical direction that we interpret as a refractive index gradient lowering reflectivity further down. The coating formed at 180 °C shows the lowest average reflectivity (2.9%), and presents an interesting deep black diffuse aspect.

  6. Synthesis of mullite coatings by chemical vapor deposition

    SciTech Connect

    Mulpuri, R.P.; Auger, M.; Sarin, V.K.

    1996-08-01

    Formation of mullite on ceramic substrates via chemical vapor deposition was investigated. Mullite is a solid solution of Al{sub 2}O{sub 3} and SiO{sub 2} with a composition of 3Al{sub 2}O{sub 3}{circ}2SiO{sub 2}. Thermodynamic calculations performed on the AlCl{sub 3}-SiCl{sub 4}-CO{sub 2}-H{sub 2} system were used to construct equilibrium CVD phase diagrams. With the aid of these diagrams and consideration of kinetic rate limiting factors, initial process parameters were determined. Through process optimization, crystalline CVD mullite coatings have been successfully grown on SiC and Si{sub 3}N{sub 4} substrates. Results from the thermodynamic analysis, process optimization, and effect of various process parameters on deposition rate and coating morphology are discussed.

  7. Electrical and chemical characterization of FIB-deposited insulators

    SciTech Connect

    Campbell, A.N.; Tanner, D.M.; Soden, J.M.; Adams, E.; Gibson, M.; Abramo, M.; Doyle, A.; Stewart, D.K.

    1997-10-01

    The electrical and chemical properties of insulators produced by codeposition of siloxane compounds or TEOS with oxygen in a focused ion beam (FIB) system were investigated. Metal-insulator-metal capacitor structures were fabricated and tested. Specifically, leakage current and breakdown voltage were measured and used to calculate the effective resistance and breakdown field. Capacitance measurements were performed on a subset of the structures. It was found that the siloxane-based FIB-insulators had superior electrical properties to those based on TEOS. Microbeam Rutherford backscattering spectrometry analysis and Fourier transform infrared spectroscopy were used to characterize the films and to help understand the differences in electrical behavior as a function of gas chemistry and deposition conditions. Finally, a comparison is made between the results presented here, previous results for FIB-deposited insulators, and typical thermally-grown gate oxides and interlevel dielectric SiO{sub 2} insulators.

  8. Regenerate metal-plating baths to cut waste and save

    SciTech Connect

    1995-03-01

    During electrode-based metal plating of equipment components, the formation of an electrical field causes metal deposits to be thicker at edges and seams, and thinner on flat surfaces. And, electrode-based methods consume large amounts of energy. Electroless-nickel (EN) -- or autocatalytic -- plating systems were pioneered in the 1940s to solve these problems. EN plating produces a more uniform coating, irrespective of the complexity of the part, and it consumes less electricity, since to electric current is required during plating. Plating in an EN system results from a chemical reaction between nickel in the bath and the substrate of the equipment component. The downside of electroless plating, however, is the limited life of the nickel bath, and the large volume of metal waste produced by bath disposal. Ionsep Corp. (Wilmington, Del.) has developed an electrodialytic system that continuously reforms the EN plating baths, to give them longer life. Its patented system has been successfully laboratory tested in a 1-ft{sup 2} cell, and the firm recently won a $250,000 grant from the US Dept. of Energy (Washington, D.C.) and Environmental Protection Agency (Washington, D.C.), to design and engineer a commercial-scale version of the system.

  9. Characterisation of TiO 2 deposited by photo-induced chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Kaliwoh, Never; Zhang, Jun-Ying; Boyd, Ian W.

    2002-01-01

    We report the deposition of thin TiO 2 films on crystalline Si and quartz by photo-induced chemical vapour deposition (CVD) using UV excimer lamps employing a dielectric barrier discharge in krypton chloride (KrCl ∗) to provide intense narrow band radiation at λ=222 nm. The precursor used was titanium isopropoxide (TTIP). Films from around 20-510 nm in thickness with refractive indices from 2.20 to 2.54 were grown at temperatures between 50 and 350 °C. The higher refractive index values compare favourably with the value of 2.58 recorded for the bulk material. The measured deposition rate was around 50 nm/min at 350 °C. Fourier transform infrared spectroscopy (FTIR) revealed the presence of TiO 2 through the observation of a Ti-O absorption peak and the absence of OH in films deposited at 250-350 °C indicated relatively good quality films. The phase of films deposited at 200-350 °C was anatase as determined by X-ray diffraction.

  10. Unusual thermopower of inhomogeneous graphene grown by chemical vapor deposition

    SciTech Connect

    Nam, Youngwoo; Sun, Jie; Lindvall, Niclas; Yurgens, August; Jae Yang, Seung; Rae Park, Chong; Woo Park, Yung

    2014-01-13

    We report on thermopower (TEP) and resistance measurements of inhomogeneous graphene grown by chemical vapor deposition (CVD). Unlike the conventional resistance of pristine graphene, the gate-dependent TEP shows a large electron-hole asymmetry. This can be accounted for by inhomogeneity of the CVD-graphene where individual graphene regions contribute with different TEPs. At the high magnetic field and low temperature, the TEP has large fluctuations near the Dirac point associated with the disorder in the CVD-graphene. TEP measurements reveal additional characteristics of CVD-graphene, which are difficult to obtain from the measurement of resistance alone.

  11. Unusual thermopower of inhomogeneous graphene grown by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Nam, Youngwoo; Sun, Jie; Lindvall, Niclas; Jae Yang, Seung; Rae Park, Chong; Woo Park, Yung; Yurgens, August

    2014-01-01

    We report on thermopower (TEP) and resistance measurements of inhomogeneous graphene grown by chemical vapor deposition (CVD). Unlike the conventional resistance of pristine graphene, the gate-dependent TEP shows a large electron-hole asymmetry. This can be accounted for by inhomogeneity of the CVD-graphene where individual graphene regions contribute with different TEPs. At the high magnetic field and low temperature, the TEP has large fluctuations near the Dirac point associated with the disorder in the CVD-graphene. TEP measurements reveal additional characteristics of CVD-graphene, which are difficult to obtain from the measurement of resistance alone.

  12. Microscopic characterisation of suspended graphene grown by chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Bignardi, Luca; van Dorp, Willem F.; Gottardi, Stefano; Ivashenko, Oleksii; Dudin, Pavel; Barinov, Alexei; de Hosson, Jeff Th. M.; Stöhr, Meike; Rudolf, Petra

    2013-09-01

    We present a multi-technique characterisation of graphene grown by chemical vapour deposition (CVD) and thereafter transferred to and suspended on a grid for transmission electron microscopy (TEM). The properties of the electronic band structure are investigated by angle-resolved photoelectron spectromicroscopy, while the structural and crystalline properties are studied by TEM and Raman spectroscopy. We demonstrate that the suspended graphene membrane locally shows electronic properties comparable with those of samples prepared by micromechanical cleaving of graphite. Measurements show that the area of high quality suspended graphene is limited by the folding of the graphene during the transfer.

  13. Microscopic characterisation of suspended graphene grown by chemical vapour deposition.

    PubMed

    Bignardi, Luca; van Dorp, Willem F; Gottardi, Stefano; Ivashenko, Oleksii; Dudin, Pavel; Barinov, Alexei; De Hosson, Jeff Th M; Stöhr, Meike; Rudolf, Petra

    2013-10-01

    We present a multi-technique characterisation of graphene grown by chemical vapour deposition (CVD) and thereafter transferred to and suspended on a grid for transmission electron microscopy (TEM). The properties of the electronic band structure are investigated by angle-resolved photoelectron spectromicroscopy, while the structural and crystalline properties are studied by TEM and Raman spectroscopy. We demonstrate that the suspended graphene membrane locally shows electronic properties comparable with those of samples prepared by micromechanical cleaving of graphite. Measurements show that the area of high quality suspended graphene is limited by the folding of the graphene during the transfer. PMID:23945527

  14. Chemical vapor deposited silicon carbide mirrors for extreme ultraviolet applications

    NASA Astrophysics Data System (ADS)

    Keski-Kuha, Ritva A.; Osantowski, John F.; Leviton, Douglas B.; Saha, Timo T.; Wright, Geraldine A.; Boucarut, Rene A.; Fleetwood, Charles M.; Madison, Timothy J.

    1997-01-01

    Advances in optical coating and materials technology have made possible the development of instruments with substantially improved efficiency in the extreme ultraviolet (EUV). For example, the development of the chemical vapor deposition (CVD) SiC mirrors provides an opportunity to extend the range of normal-incidence instruments dow to 60 nm. CVD SiC is a highly polishable material yielding low- scattering surfaces. High UV reflectivity and desirable mechanical and thermal properties make CVD SiC an attractive mirror and/or coating material for EUV applications. The EUV performance of SiC mirrors, as well as some strengths and problem areas, is discussed.

  15. Damping mechanisms in chemically vapor deposited SiC fibers

    NASA Technical Reports Server (NTRS)

    Dicarlo, James A.; Goldsby, Jon C.

    1993-01-01

    Evaluating the damping of reinforcement fibers is important for understanding their microstructures and the vibrational response of their structural composites. In this study the damping capacities of two types of chemically vapor deposited silicon carbide fibers were measured from -200 C to as high as 800 C. Measurements were made at frequencies in the range 50 to 15000 Hz on single cantilevered fibers. At least four sources were identified which contribute to fiber damping, the most significant being thermoelastic damping and grain boundary sliding. The mechanisms controlling all sources and their potential influence on fiber and composite performance are discussed.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  17. Chemical Vapor Deposited Zinc Sulfide. SPIE Press Monograph

    SciTech Connect

    McCloy, John S.; Tustison, Randal W.

    2013-04-22

    Zinc sulfide has shown unequaled utility for infrared windows that require a combination of long-wavelength infrared transparency, mechanical durability, and elevated-temperature performance. This book reviews the physical properties of chemical vapor deposited ZnS and their relationship to the CVD process that produced them. An in-depth look at the material microstructure is included, along with a discussion of the material's optical properties. Finally, because the CVD process itself is central to the development of this material, a brief history is presented.

  18. Low Temperature Deposition of β-phase Silicon Nitride Using Inductively Coupled Plasma Chemical Vapor Deposition Technique

    NASA Astrophysics Data System (ADS)

    Kshirsagar, Abhijeet; Duttagupta, S. P.; Gangal, S. A.

    2010-12-01

    Silicon nitride (SiN) films have been deposited at low temperature (≤100° C), by Inductively Coupled Plasma Chemical Vapor Deposition (ICPCVD) technique. The chemical and physical properties of deposited SiN films such as refractive index, deposition rate, and film stress have been measured. Additional structural characterization is performed using X-ray diffraction (XRD) and Micro Raman Spectroscopy. It is found that the films obtained are of low stress and have β-phase. To the best of authors knowledge such low temperature, low stress, β-phase SiN films deposition using ICPCVD are being reported for the first time.

  19. ZnS nanoflakes deposition by modified chemical method

    SciTech Connect

    Desai, Mangesh A. Sartale, S. D.

    2014-04-24

    We report deposition of zinc sulfide nanoflakes on glass substrates by modified chemical method. The modified chemical method involves adsorption of zinc–thiourea complex on the substrate and its dissociation in presence of hydroxide ions to release sulfur ions from thiourea which react with zinc ions present in the complex to form zinc sulfide nanoflakes at room temperature. Influence of zinc salt and thiourea concentrations ratios on the morphology of the films was investigated by scanning electron microscope (SEM). The ratio of zinc and thiourea in the zinc–thiourea complex significantly affect the size of the zinc sulfide nanoflakes, especially width and density of the nanoflakes. The X-ray diffraction analysis exhibits polycrystalline nature of the zinc sulfide nanoflakes with hexagonal phase.

  20. Chemical vapor deposition of conformal, functional, and responsive polymer films.

    PubMed

    Alf, Mahriah E; Asatekin, Ayse; Barr, Miles C; Baxamusa, Salmaan H; Chelawat, Hitesh; Ozaydin-Ince, Gozde; Petruczok, Christy D; Sreenivasan, Ramaswamy; Tenhaeff, Wyatt E; Trujillo, Nathan J; Vaddiraju, Sreeram; Xu, Jingjing; Gleason, Karen K

    2010-05-11

    Chemical vapor deposition (CVD) polymerization utilizes the delivery of vapor-phase monomers to form chemically well-defined polymeric films directly on the surface of a substrate. CVD polymers are desirable as conformal surface modification layers exhibiting strong retention of organic functional groups, and, in some cases, are responsive to external stimuli. Traditional wet-chemical chain- and step-growth mechanisms guide the development of new heterogeneous CVD polymerization techniques. Commonality with inorganic CVD methods facilitates the fabrication of hybrid devices. CVD polymers bridge microfabrication technology with chemical, biological, and nanoparticle systems and assembly. Robust interfaces can be achieved through covalent grafting enabling high-resolution (60 nm) patterning, even on flexible substrates. Utilizing only low-energy input to drive selective chemistry, modest vacuum, and room-temperature substrates, CVD polymerization is compatible with thermally sensitive substrates, such as paper, textiles, and plastics. CVD methods are particularly valuable for insoluble and infusible films, including fluoropolymers, electrically conductive polymers, and controllably crosslinked networks and for the potential to reduce environmental, health, and safety impacts associated with solvents. Quantitative models aid the development of large-area and roll-to-roll CVD polymer reactors. Relevant background, fundamental principles, and selected applications are reviewed. PMID:20544886

  1. Fundamental studies of the chemical vapor deposition of diamond

    SciTech Connect

    Stevenson, D.A.

    1991-01-01

    The plasma or thermally enhanced low pressure chemical vapor deposition of diamond films is an exciting development with many challenging fundamental problems. The early stages of nucleation is relevant to the initial growth rate and the perfection and morphology of the deposit. To isolate one of the factors that influence nucleation, we have studied the effect of surface topography on the nucleation process. Our earlier work has shown preferential nucleation on sharp convex features and we have proposed several possible reasons for this behavior, including dangling bonds at the convex features. In our recent work, we have extended our investigation to include a novel patterning of silicon substrates used to pattern silicon solar cells. The results are consistent with our earlier observations that the majority of nucleation events occur on protruding surface features. In an effort to establish whether dangling bonds at the protruding surfaces may be responsible for the selective nucleation, we have evaluated the dangling bond concentration using electron spin resonance. We have carried out deposition under nominally identical surface topography, but with different concentrations of dangling bonds at or near the surface. The results of this study indicate that dangling bonds play a minor role in enhancing nucleation, in contrast to a substantial role played by special surface topographical features. In the course of the past year, we have submitted four manuscripts for publication and have made six presentations.

  2. Solvent-assisted dewetting during chemical vapor deposition.

    PubMed

    Chen, Xichong; Anthamatten, Mitchell

    2009-10-01

    This study examines the use of a nonreactive solvent vapor, tert-butanol, during initiated chemical vapor deposition (iCVD) to promote polymer film dewetting. iCVD is a solventless technique to grow polymer thin films directly from gas phase feeds. Using a custom-built axisymmetric hot-zone reactor, smooth poly(methyl methacrylate) films are grown from methyl methacrylate (MMA) and tert-butyl peroxide (TBPO). When solvent vapor is used, nonequilibrium dewetted structures comprising of randomly distributed polymer droplets are observed. The length scale of observed topographies, determined using power spectral density (PSD) analysis, ranges from 5 to 100 microm and is influenced by deposition conditions, especially the carrier gas and solvent vapor flow rates. The use of a carrier gas leads to faster deposition rates and suppresses thin film dewetting. The use of solvent vapor promotes dewetting and leads to larger length scales of the dewetted features. Control over lateral length scale is demonstrated by preparation of hierarchal "bump on bump" topographies. Vapor-induced dewetting is demonstrated on silicon wafer substrate with a native oxide layer and also on hydrophobically modified substrate prepared using silane coupling. Autophobic dewetting of PMMA from SiOx/Si during iCVD is attributed to a thin film instability driven by both long-range van der Waals forces and short-range polar interactions. PMID:19670895

  3. Chemical vapor deposition of amorphous silicon films from disilane

    SciTech Connect

    Bogaert, R.J.

    1986-01-01

    Amorphous silicon films for fabrication of solar cells have been deposited by thermal chemical vapor deposition (CVD) from disilane (Si/sub 2/H/sub 6/) using a tubular flow reactor. A mathematical description for the CVD reactor was developed and solved by a numerical procedure. The proposed chemical reaction network for the model is based on silylene (SiH/sub 2/) insertion in the gas phase and film growth from SiH/sub 2/ and silicon polymers (Si/sub n/N/sub 2n/, n approx. 10). Estimates of the rate constants have been obtained for trisilane decomposition, silicon polymer formation, and polymer dehydrogenation. The silane unimolecular decomposition rate constants were corrected for pressure effects. The model behavior is compared to the experimental results over the range of conditions: reactor temperature (360 to 485/sup 0/C), pressures (2 to 48 torr), and gas holding time (1 to 70 s). Within the above range of conditions, film growth rate varies from 0.01 to 30 A/s. Results indicate that silicon polymers are the main film precursors for gas holding times greater than 3 s. Film growth by silylene only becomes important at short holding times, large inert gas dilution, and positions near the beginning of the reactor hot zone.

  4. Conversion Coatings for Aluminum Alloys by Chemical Vapor Deposition Mechanisms

    NASA Technical Reports Server (NTRS)

    Reye, John T.; McFadden, Lisa S.; Gatica, Jorge E.; Morales, Wilfredo

    2004-01-01

    With the rise of environmental awareness and the renewed importance of environmentally friendly processes, the United States Environmental Protection Agency has targeted surface pre-treatment processes based on chromates. Indeed, this process has been subject to regulations under the Clean Water Act as well as other environmental initiatives, and there is today a marked movement to phase the process out in the near future. Therefore, there is a clear need for new advances in coating technology that could provide practical options for replacing present industrial practices. Depending on the final application, such coatings might be required to be resistant to corrosion, act as chemically resistant coatings, or both. This research examined a chemical vapor deposition (CVD) mechanism to deposit uniform conversion coatings onto aluminum alloy substrates. Robust protocols based on solutions of aryl phosphate ester and multi-oxide conversion coating (submicron) films were successfully grown onto the aluminum alloy samples. These films were characterized by X-ray Photoelectron Spectroscopy (XPS). Preliminary results indicate the potential of this technology to replace aqueous-based chromate processes.

  5. Deposition of aligned bamboo-like carbon nanotubes via microwave plasma enhanced chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Cui, H.; Zhou, O.; Stoner, B. R.

    2000-11-01

    Aligned multiwall carbon nanotubes have been grown on silicon substrates by microwave plasma enhanced chemical vapor deposition using methane/ammonia mixtures. Scanning electron microscopy shows that the nanotubes are well aligned with high aspect ratio and growth direction normal to the substrate. Transmission electron microscopy reveals that the majority phase has a bamboo-like structure. Data are also presented showing process variable effects on the size and microstructure of the aligned nanotubes, giving insight into possible nucleation and growth mechanisms for the process.

  6. NASA evaluation of Type 2 chemical depositions. [effects of deicer deposition on aircraft tire friction performance

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.; Stubbs, Sandy M.; Howell, W. Edward; Webb, Granville L.

    1993-01-01

    Recent findings from NASA Langley tests to define effects of aircraft Type 2 chemical deicer depositions on aircraft tire friction performance are summarized. The Aircraft Landing Dynamics Facility (ALDF) is described together with the scope of the tire cornering and braking friction tests conducted up to 160 knots ground speed. Some lower speed 32 - 96 km/hr (20 - 60 mph) test run data obtained using an Instrumented Tire Test Vehicle (ITTV) to determine effects of tire bearing pressure and transverse grooving on cornering friction performance are also discussed. Recommendations are made concerning which parameters should be evaluated in future testing.

  7. Growth of graphene films by plasma enhanced chemical vapour deposition

    NASA Astrophysics Data System (ADS)

    Baraton, Laurent; Gangloff, Laurent; Xavier, Stéphane; Cojocaru, Costel S.; Huc, Vincent; Legagneux, Pierre; Lee, Young Hee; Pribat, Didier

    2009-08-01

    Since it was isolated in 2004, graphene, the first known 2D crystal, is the object of a growing interest, due to the range of its possible applications as well as its intrinsic properties. From large scale electronics and photovoltaics to spintronics and fundamental quantum phenomena, graphene films have attracted a large community of researchers. But bringing graphene to industrial applications will require a reliable, low cost and easily scalable synthesis process. In this paper we present a new growth process based on plasma enhanced chemical vapor deposition. Furthermore, we show that, when the substrate is an oxidized silicon wafer covered by a nickel thin film, graphene is formed not only on top of the nickel film, but also at the interface with the supporting SiO2 layer. The films grown using this method were characterized using classical methods (Raman spectroscopy, AFM, SEM) and their conductivity is found to be close to those reported by others.

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

    NASA Technical Reports Server (NTRS)

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

    1989-01-01

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

  9. Chemical vapor deposition growth of patterned graphene on copper

    NASA Astrophysics Data System (ADS)

    Gutierrez, Humberto; Wang, Bei; Zhu, J.

    2010-03-01

    Graphene possesses unique electronic properties and application potentials. However, the synthesis of high-quality, single-layer graphene on large scale remains challenging. Mechanical exfoliation from graphite crystals yields graphene of the highest quality but in an uncontrolled and non-scalable way. Epitaxial growth on SiC has made significant advances in large-scale synthesis, although the cost is relatively high. Very recently, chemical vapor deposition (CVD) is used to grow graphene on Ni and Cu surfaces and has also produced large-area graphene of reasonably high quality. Cracks and ripples, however, present considerable challenges to the CVD growth and transfer process. We report the CVD growth of single-layer graphene on patterned, micron-size copper templates. Raman spectra of the films show low D-band and relatively narrow 2D peak, suggesting high quality. We present and discuss the transport properties of graphene films transferred onto an insulating substrate.

  10. Chemical vapor deposition fluid flow simulation modelling tool

    NASA Technical Reports Server (NTRS)

    Bullister, Edward T.

    1992-01-01

    Accurate numerical simulation of chemical vapor deposition (CVD) processes requires a general purpose computational fluid dynamics package combined with specialized capabilities for high temperature chemistry. In this report, we describe the implementation of these specialized capabilities in the spectral element code NEKTON. The thermal expansion of the gases involved is shown to be accurately approximated by the low Mach number perturbation expansion of the incompressible Navier-Stokes equations. The radiative heat transfer between multiple interacting radiating surfaces is shown to be tractable using the method of Gebhart. The disparate rates of reaction and diffusion in CVD processes are calculated via a point-implicit time integration scheme. We demonstrate the use above capabilities on prototypical CVD applications.

  11. Synthesis of large-size graphene by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Wu, Ruizhe; Ding, Yao; Gan, Lin; Luo, Zhengtang

    2015-09-01

    The requirement for long-range structure coherence and property uniformity for graphene-based electronics are crucial for their applications in electronics. Here, we briefly review our recent progress on synthesis of large-size graphene by seeded growth method. We demonstrate a seeded growth method which allows us to reduce the nucleation density in early stage of Chemical Vapor Deposition (CVD) leading to the production of low density of graphene grains and consequently achieve grain size of sub-centimeter. We further demonstrate that we can amplify the graphene grain size by limiting the second seeded growth only from the graphene seed edges. Moreover, we demonstrate that similar method can be used for the preparation of large-grain bilayer graphene flakes.

  12. Chemical Vapor Deposition at High Pressure in a Microgravity Environment

    NASA Technical Reports Server (NTRS)

    McCall, Sonya; Bachmann, Klaus; LeSure, Stacie; Sukidi, Nkadi; Wang, Fuchao

    1999-01-01

    In this paper we present an evaluation of critical requirements of organometallic chemical vapor deposition (OMCVD) at elevated pressure for a channel flow reactor in a microgravity environment. The objective of using high pressure is to maintain single-phase surface composition for materials that have high thermal decomposition pressure at their optimum growth temperature. Access to microgravity is needed to maintain conditions of laminar flow, which is essential for process analysis. Based on ground based observations we present an optimized reactor design for OMCVD at high pressure and reduced gravity. Also, we discuss non-intrusive real-time optical monitoring of flow dynamics coupled to homogeneous gas phase reactions, transport and surface processes. While suborbital flights may suffice for studies of initial stages of heteroepitaxy experiments in space are essential for a complete evaluation of steady-state growth.

  13. Optics applications of chemical vapor deposited beta-SiC

    NASA Astrophysics Data System (ADS)

    Goela, Jitendra S.; Pickering, Michael A.

    1997-09-01

    The fabrication process, properties and optics applications of transparent and opaque chemical vapor deposited (CVD) (beta) -SiC are reviewed. CVD-SiC is produced by the pyrolysis of methyltrichlorosilane, in excess H2, in a low-pressure CVD reactor. The CVD process has been successfully scaled to produce monolithic SiC parts of diameter up to 1.5-m and thickness 2.5-cm. The characterization of CVD-SiC for important physical, optical, mechanical and thermal properties indicates that it is a superior material for optics applications. Important properties of CVD-SiC are compared with those of the other candidate mirror and window materials. The applications of CVD-SiC for lightweight optics, x-ray telescopes, optical buffers, lens molds, optical standards and windows and domes are discussed in detail.

  14. Chemical vapor deposited {beta}-SiC for optics applications

    SciTech Connect

    Goela, J.S.; Pikcering, M.A.; Taylor, R.L.

    1995-08-01

    The fabrication, properties and optics applications of transparent and opaque Chemical Vapor Deposited (CVD) {beta}-SiC are reviewed. CVD-SiC is fabricated by the pyrolysis of methyltrichlorosilane, in excess H{sub 2}, in a low-pressure CVD reactor. The CVD process has been successfully scaled to produce monolithic SiC parts of diameter up to 1.5 m and thickness 2.5 cm. The characterization of CVD-SiC for important physical, optical, mechanical and thermal properties indicate that it is a superior material for optics applications. CVD-SiC properties are compared with those of the other candidate mirror and window materials. SiC process/property relationships are discussed, emphasizing the differences in process conditions, microstructure, and properties between transparent and opaque CVD-SiC.

  15. Strain relaxation in graphene grown by chemical vapor deposition

    SciTech Connect

    Troppenz, Gerald V. Gluba, Marc A.; Kraft, Marco; Rappich, Jörg; Nickel, Norbert H.

    2013-12-07

    The growth of single layer graphene by chemical vapor deposition on polycrystalline Cu substrates induces large internal biaxial compressive strain due to thermal expansion mismatch. Raman backscattering spectroscopy and atomic force microscopy were used to study the strain relaxation during and after the transfer process from Cu foil to SiO{sub 2}. Interestingly, the growth of graphene results in a pronounced ripple structure on the Cu substrate that is indicative of strain relaxation of about 0.76% during the cooling from the growth temperature. Removing graphene from the Cu substrates and transferring it to SiO{sub 2} results in a shift of the 2D phonon line by 27 cm{sup −1} to lower frequencies. This translates into additional strain relaxation. The influence of the processing steps, used etching solution and solvents on strain, is investigated.

  16. Creep of chemically vapor deposited SiC fibers

    NASA Technical Reports Server (NTRS)

    Dicarlo, J. A.

    1984-01-01

    The creep, thermal expansion, and elastic modulus properties for chemically vapor deposited SiC fibers were measured between 1000 and 1500 C. Creep strain was observed to increase logarithmically with time, monotonically with temperature, and linearly with tensile stress up to 600 MPa. The controlling activation energy was 480 + or - 20 kJ/mole. Thermal pretreatments near 1200 and 1450 C were found to significantly reduce fiber creep. These results coupled with creep recovery observations indicate that below 1400 C fiber creep is anelastic with neglible plastic component. This allowed a simple predictive method to be developed for describing fiber total deformation as a function of time, temperature, and stress. Mechanistic analysis of the property data suggests that fiber creep is the result of beta-SiC grain boundary sliding controlled by a small percent of free silicon in the grain boundaries.

  17. Chemical vapour deposition synthetic diamond: materials, technology and applications

    NASA Astrophysics Data System (ADS)

    Balmer, R. S.; Brandon, J. R.; Clewes, S. L.; Dhillon, H. K.; Dodson, J. M.; Friel, I.; Inglis, P. N.; Madgwick, T. D.; Markham, M. L.; Mollart, T. P.; Perkins, N.; Scarsbrook, G. A.; Twitchen, D. J.; Whitehead, A. J.; Wilman, J. J.; Woollard, S. M.

    2009-09-01

    Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synthesized in planar form; however, non-planar geometries are also possible and enable a number of key applications. This paper reviews the material properties and characteristics of single crystal and polycrystalline CVD diamond, and how these can be utilized, focusing particularly on optics, electronics and electrochemistry. It also summarizes how CVD diamond can be tailored for specific applications, on the basis of the ability to synthesize a consistent and engineered high performance product.

  18. Chemical vapour deposition synthetic diamond: materials, technology and applications.

    PubMed

    Balmer, R S; Brandon, J R; Clewes, S L; Dhillon, H K; Dodson, J M; Friel, I; Inglis, P N; Madgwick, T D; Markham, M L; Mollart, T P; Perkins, N; Scarsbrook, G A; Twitchen, D J; Whitehead, A J; Wilman, J J; Woollard, S M

    2009-09-01

    Substantial developments have been achieved in the synthesis of chemical vapour deposition (CVD) diamond in recent years, providing engineers and designers with access to a large range of new diamond materials. CVD diamond has a number of outstanding material properties that can enable exceptional performance in applications as diverse as medical diagnostics, water treatment, radiation detection, high power electronics, consumer audio, magnetometry and novel lasers. Often the material is synthesized in planar form; however, non-planar geometries are also possible and enable a number of key applications. This paper reviews the material properties and characteristics of single crystal and polycrystalline CVD diamond, and how these can be utilized, focusing particularly on optics, electronics and electrochemistry. It also summarizes how CVD diamond can be tailored for specific applications, on the basis of the ability to synthesize a consistent and engineered high performance product. PMID:21832327

  19. Characterization of Carbon Nanotubes Grown by Chemical Vapor Deposition

    NASA Technical Reports Server (NTRS)

    Cochrane, J. C.; Zhu, Shen; Su, Ching-Hua; Lehoczky, S. L.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Since the superior properties of multi-wall carbon nanotubes (MWCNT) could improve numerous devices such as electronics and sensors, many efforts have been made in investigating the growth mechanism of MWCNT to synthesize high quality MWCNT. Chemical vapor deposition (CVD) is widely used for MWCNT synthesis, and scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) are useful methods for analyzing the structure, morphology and composition of MWCNT. Temperature and pressure are two important growth parameters for fabricating carbon nanotubes. In MWCNT growth by CVD, the plasma assisted method is normally used for low temperature growth. However a high temperature environment is required for thermal CVD. A systematic study of temperature and pressure-dependence is very helpful to understanding MWCNT growth. Transition metal particles are commonly used as catalysis in carbon nanotube growth. It is also interesting to know how temperature and pressure affect the interface of carbon species and catalyst particles

  20. Low Temperature Chemical Vapor Deposition Of Thin Film Magnets

    DOEpatents

    Miller, Joel S.; Pokhodnya, Kostyantyn I.

    2003-12-09

    A thin-film magnet formed from a gas-phase reaction of tetracyanoetheylene (TCNE) OR (TCNQ), 7,7,8,8-tetracyano-P-quinodimethane, and a vanadium-containing compound such as vanadium hexcarbonyl (V(CO).sub.6) and bis(benzene)vanalium (V(C.sub.6 H.sub.6).sub.2) and a process of forming a magnetic thin film upon at least one substrate by chemical vapor deposition (CVD) at a process temperature not exceeding approximately 90.degree. C. and in the absence of a solvent. The magnetic thin film is particularly suitable for being disposed upon rigid or flexible substrates at temperatures in the range of 40.degree. C. and 70.degree. C. The present invention exhibits air-stable characteristics and qualities and is particularly suitable for providing being disposed upon a wide variety of substrates.

  1. Development and evaluation of chemically inpregnated filter for deposition monitoring

    SciTech Connect

    Fung, K. )

    1988-01-01

    The Operational and Evaluation Network (OEN) and the Acid Model Operational Diagnostic Model Evaluation Study (ACID MODES) are large scale regional networks sponsored respectively by the Electric Power Research Institute (EPRI) and the U.S. Environmental Protection Agency to collect daily average concentration data of particles and gases for the evaluation of acid deposition models such as the Acid Deposition and Oxidant Model (ADOM) and the Regional Acid Deposition Model (RADM). Data from two Canadian Networks, CAPMoN and APIOS, will also be incorporated for the evaluation purpose. While the design of the sampler may vary, a basic sampling unit common to these programs is the filter pack, which has two or more filters in a stacked arrangement, depending on the application. The top filter, usually Teflon, is used to collect or remove particles from the sampling air stream. The subsequent filters are for the collection of gases: Nylon for HNO{sub 3} and volatilized nitrate, citric acid-impregnated filter for NH{sub 3}, triethanolamine (TEA)-impregnated filter for NO{sub 2}, and K{sub 2}CO{sub 3}-impregnated filter for SO{sub 2}. These various chemically treated filters have been used previously. But since the monitoring is conducted year-round over very large geographic areas, the diversity of the climatic conditions under which sampling will be conducted may seriously affect the performance of these filters. Also, when multiple filters are stacked for the collection of various gases, their order of arrangement as well as pressure drop must be considered in terms of filter collection selectivity and pump performance. This paper reports on a series of tests that were conducted to address these various issues to ensure that the measurements will be conducted successfully in these programs.

  2. Design and implementation of a novel portable atomic layer deposition/chemical vapor deposition hybrid reactor

    NASA Astrophysics Data System (ADS)

    Selvaraj, Sathees Kannan; Jursich, Gregory; Takoudis, Christos G.

    2013-09-01

    We report the development of a novel portable atomic layer deposition chemical vapor deposition (ALD/CVD) hybrid reactor setup. Unique feature of this reactor is the use of ALD/CVD mode in a single portable deposition system to fabricate multi-layer thin films over a broad range from "bulk-like" multi-micrometer to nanometer atomic dimensions. The precursor delivery system and control-architecture are designed so that continuous reactant flows for CVD and cyclic pulsating flows for ALD mode are facilitated. A custom-written LabVIEW program controls the valve sequencing to allow synthesis of different kinds of film structures under either ALD or CVD mode or both. The entire reactor setup weighs less than 40 lb and has a relatively small footprint of 8 × 9 in., making it compact and easy for transportation. The reactor is tested in the ALD mode with titanium oxide (TiO2) ALD using tetrakis(diethylamino)titanium and water vapor. The resulting growth rate of 0.04 nm/cycle and purity of the films are in good agreement with literature values. The ALD/CVD hybrid mode is demonstrated with ALD of TiO2 and CVD of tin oxide (SnOx). Transmission electron microscopy images of the resulting films confirm the formation of successive distinct TiO2-ALD and SnOx-CVD layers.

  3. Amorphous Carbon Deposited by a Novel Aerosol-Assisted Chemical Vapor Deposition for Photovoltaic Solar Cells

    NASA Astrophysics Data System (ADS)

    Ahmad, Nurfadzilah; Kamaruzzaman, Dayana; Rusop, Mohamad

    2012-06-01

    Amorphous carbon (a-C) solar cells were successfully prepared using a novel and self-designed aerosol-assisted chemical vapor deposition (AACVD) method using camphor oil as a precursor. The fabricated solar cell with the configuration of Au/p-C/n-Si/Au achieved an efficiency of 0.008% with a fill factor of 0.15 for the device deposited at 0.5 h. The current-voltage (I-V) graph emphasized on the linear graph (ohmic) for the a-C thin films, whereas for the p-n device structure, a rectifying curve was obtained. The rectifying curves signify the heterojunction between the p-type a-C film and the n-Si substrate and designate the generation of electron-hole pair of the samples under illumination. Photoresponse characteristics of the deposited a-C was highlighted when being illuminated (AM 1.5 illumination: 100 mW/cm2, 25 °C). Transmittance spectrum exhibit a large transmittance value (>85%) and absorption coefficient value of 103-104 cm-1 at the visible range of 390 to 790 nm. The atomization of a liquid precursor solution into fine sub-micrometre-sized aerosol droplets in AACVD induced the smooth surface of a-C films. To the best of our knowledge, fabrication of a-C solar cell using this AACVD method has not yet been reported.

  4. Design and implementation of a novel portable atomic layer deposition/chemical vapor deposition hybrid reactor.

    PubMed

    Selvaraj, Sathees Kannan; Jursich, Gregory; Takoudis, Christos G

    2013-09-01

    We report the development of a novel portable atomic layer deposition chemical vapor deposition (ALD/CVD) hybrid reactor setup. Unique feature of this reactor is the use of ALD/CVD mode in a single portable deposition system to fabricate multi-layer thin films over a broad range from "bulk-like" multi-micrometer to nanometer atomic dimensions. The precursor delivery system and control-architecture are designed so that continuous reactant flows for CVD and cyclic pulsating flows for ALD mode are facilitated. A custom-written LabVIEW program controls the valve sequencing to allow synthesis of different kinds of film structures under either ALD or CVD mode or both. The entire reactor setup weighs less than 40 lb and has a relatively small footprint of 8 × 9 in., making it compact and easy for transportation. The reactor is tested in the ALD mode with titanium oxide (TiO2) ALD using tetrakis(diethylamino)titanium and water vapor. The resulting growth rate of 0.04 nm/cycle and purity of the films are in good agreement with literature values. The ALD/CVD hybrid mode is demonstrated with ALD of TiO2 and CVD of tin oxide (SnOx). Transmission electron microscopy images of the resulting films confirm the formation of successive distinct TiO2-ALD and SnO(x)-CVD layers. PMID:24089868

  5. Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene.

    PubMed

    Harberts, Megan; Lu, Yu; Yu, Howard; Epstein, Arthur J; Johnston-Halperin, Ezekiel

    2015-01-01

    Recent progress in the field of organic materials has yielded devices such as organic light emitting diodes (OLEDs) which have advantages not found in traditional materials, including low cost and mechanical flexibility. In a similar vein, it would be advantageous to expand the use of organics into high frequency electronics and spin-based electronics. This work presents a synthetic process for the growth of thin films of the room temperature organic ferrimagnet, vanadium tetracyanoethylene (V[TCNE]x, x~2) by low temperature chemical vapor deposition (CVD). The thin film is grown at <60 °C, and can accommodate a wide variety of substrates including, but not limited to, silicon, glass, Teflon and flexible substrates. The conformal deposition is conducive to pre-patterned and three-dimensional structures as well. Additionally this technique can yield films with thicknesses ranging from 30 nm to several microns. Recent progress in optimization of film growth creates a film whose qualities, such as higher Curie temperature (600 K), improved magnetic homogeneity, and narrow ferromagnetic resonance line-width (1.5 G) show promise for a variety of applications in spintronics and microwave electronics. PMID:26168285

  6. Chemical vapor deposition coatings for oxidation protection of titanium alloys

    NASA Technical Reports Server (NTRS)

    Cunnington, G. R.; Robinson, J. C.; Clark, R. K.

    1991-01-01

    Results of an experimental investigation of the oxidation protection afforded to Ti-14Al-21Nb and Ti-14Al-23Nb-2V titanium aluminides and Ti-17Mo-3Al-3Nb titanium alloy by aluminum-boron-silicon and boron-silicon coatings are presented. These coatings are applied by a combination of physical vapor deposition (PVD) and chemical vapor deposition (CVD) processes. The former is for the application of aluminum, and the latter is for codeposition of boron and silicon. Coating thickness is in the range of 2 to 7 microns, and coating weights are 0.6 to 2.0 mg/sq cm. Oxidation testing was performed in air at temperatures to 1255 K in both static and hypersonic flow environments. The degree of oxidation protection provided by the coatings is determined from weight change measurements made during the testing and post test compositional analyses. Temperature-dependent total normal emittance data are also presented for four coating/substrate combinations. Both types of coatings provided excellent oxidation protection for the exposure conditions of this investigation. Total normal emittances were greater than 0.80 in all cases.

  7. Thirty Gigahertz Optoelectronic Mixing in Chemical Vapor Deposited Graphene.

    PubMed

    Montanaro, Alberto; Mzali, Sana; Mazellier, Jean-Paul; Bezencenet, Odile; Larat, Christian; Molin, Stephanie; Morvan, Loïc; Legagneux, Pierre; Dolfi, Daniel; Dlubak, Bruno; Seneor, Pierre; Martin, Marie-Blandine; Hofmann, Stephan; Robertson, John; Centeno, Alba; Zurutuza, Amaia

    2016-05-11

    The remarkable properties of graphene, such as broadband optical absorption, high carrier mobility, and short photogenerated carrier lifetime, are particularly attractive for high-frequency optoelectronic devices operating at 1.55 μm telecom wavelength. Moreover, the possibility to transfer graphene on a silicon substrate using a complementary metal-oxide-semiconductor-compatible process opens the ability to integrate electronics and optics on a single cost-effective chip. Here, we report an optoelectronic mixer based on chemical vapor-deposited graphene transferred on an oxidized silicon substrate. Our device consists in a coplanar waveguide that integrates a graphene channel, passivated with an atomic layer-deposited Al2O3 film. With this new structure, 30 GHz optoelectronic mixing in commercially available graphene is demonstrated for the first time. In particular, using a 30 GHz intensity-modulated optical signal and a 29.9 GHz electrical signal, we show frequency downconversion to 100 MHz. These results open promising perspectives in the domain of optoelectronics for radar and radio-communication systems. PMID:27043922

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

    NASA Astrophysics Data System (ADS)

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

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

  9. Selected area chemical vapor deposition of thin films for conductometric microelectronic chemical sensors

    NASA Astrophysics Data System (ADS)

    Majoo, Sanjeev

    Recent advances in microelectronics and silicon processing have been exploited to fabricate miniaturized chemical sensors. Although the capability of chemical sensing technology has grown steadily, it has been outpaced by the increasing demands for more reliable, inexpensive, and selective sensors. The diversity of applications requires the deployment of different sensing materials that have rich interfacial chemistry. However, several promising sensor materials are often incompatible with silicon micromachining and their deposition requires complicated masking steps. The new approach described here is to first micromachine a generic, instrumented, conductometric, microelectronic sensor platform that is fully functional except for the front-end sensing element. This generic platform contains a thin dielectric membrane, an integrated boron-doped silicon heater, and conductance electrodes. The membrane has low thermal mass and excellent thermal isolation. A proprietary selected-area chemical vapor deposition (SACVD) process in a cold-wall reactor at low pressures was then used to achieve maskless, self-lithographic deposition of thin films. The temperature-programmable integrated microheater initiates localized thermal decomposition/reaction of suitable CVD precursors confined to a small heated area (500 mum in diameter), and this creates the active sensing element. Platinum and titania (TiOsb2) films were deposited from pyrolysis of organometallic precursors, tetrakistrifluorophosphine platinum Pt(PFsb3)sb4 and titanium tetraisopropoxide Ti(OCH(CHsb3)sb2rbrack sb4, respectively. Deposition of gold metal films from chlorotriethylphosphine gold (Csb2Hsb5)sb3PAuCl precursor was also attempted but without success. The conductance electrodes permit in situ monitoring of film growth. The as-deposited films were characterized in situ by conductance measurements and optical microscopy and ex situ by electron microscopy and spectroscopy methods. Devices equipped with

  10. X-RAY, MICROSCOPE, AND WET CHEMICAL TECHNIQUES: COMPLEMENTARY TEAM FOR DEPOSIT ANALYSIS

    EPA Science Inventory

    Commonly used techniques for the analysis of potable water scale and corrosion deposits do not provide equivalent information about the chemical nature and significance of the deposits. ptical examination, with unaided eye and with microscopes, provides some useful information. -...