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Sample records for cdte films deposited

  1. CdTe Films Deposited by Closed-space Sublimation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    CdTe films are prepared by closed-space sublimation technology. Dependence of film crystalline on substrate materials and substrate temperature is investigated. It is found that films exhibit higher crystallinity at substrate temperature higher than 400℃. And the CdTe films deposited on CdS films with higher crystallinity have bigger crystallite and higher uniformity. Treatment with CdCl2 methanol solution promotes the crystallite growth of CdTe films during annealing.

  2. Characterization of CdTe Films Deposited at Various Bath Temperatures and Concentrations Using Electrophoretic Deposition

    Directory of Open Access Journals (Sweden)

    Zulkarnain Zainal

    2012-05-01

    Full Text Available CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111 orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the CdTe film increased with the increase of CdTe concentration. The optical energy band gap of film decreased with the increase of CdTe concentration, and with the increase of isothermal bath temperature. The film thickness increased with respect to the increase of CdTe concentration and bath temperature, and following, the numerical expression for the film thickness with respect to these two variables has been established.

  3. Characterization of CdTe films deposited at various bath temperatures and concentrations using electrophoretic deposition.

    Science.gov (United States)

    Daud, Mohd Norizam Md; Zakaria, Azmi; Jafari, Atefeh; Ghazali, Mohd Sabri Mohd; Abdullah, Wan Rafizah Wan; Zainal, Zulkarnain

    2012-01-01

    CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111) orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the CdTe film increased with the increase of CdTe concentration. The optical energy band gap of film decreased with the increase of CdTe concentration, and with the increase of isothermal bath temperature. The film thickness increased with respect to the increase of CdTe concentration and bath temperature, and following, the numerical expression for the film thickness with respect to these two variables has been established.

  4. CdTe nanoparticles for the deposition of CdTe films using close spaced sublimation

    Science.gov (United States)

    Schumm, Benjamin; Althues, Holger; Kaskel, Stefan

    2010-08-01

    In this work a nanostructured CdTe powder was applied as a source material for CdTe film deposition via Close Spaced Sublimation (CSS). Growth kinetics and the resulting film properties were studied and compared to the films deposited from a commercially available CdTe bulk powder as source. The nanostructured powder was synthesized by a solvothermal elemental reaction of Cd and Te in ethylene diamine leading to particles of around 100-500 nm in diameter with a specific surface area of 4.1 m 2 g -1. An increase in the deposition rate by the factor of 1.7 was observed for the nanostructured powder as compared to the bulk material.

  5. Characterization of CdTe Films Deposited at Various Bath Temperatures and Concentrations Using Electrophoretic Deposition

    OpenAIRE

    Zulkarnain Zainal; Mohd Norizam Md Daud; Azmi Zakaria; Mohd Sabri Mohd Ghazali; Atefeh Jafari; Wan Rafizah Wan Abdullah

    2012-01-01

    CdTe film was deposited using the electrophoretic deposition technique onto an ITO glass at various bath temperatures. Four batch film compositions were used by mixing 1 to 4 wt% concentration of CdTe powder with 10 mL of a solution of methanol and toluene. X-ray Diffraction analysis showed that the films exhibited polycrystalline nature of zinc-blende structure with the (111) orientation as the most prominent peak. From the Atomic Force Microscopy, the thickness and surface roughness of the ...

  6. Properties of RF sputtered cadmium telluride (CdTe) thin films: Influence of deposition pressure

    Science.gov (United States)

    Kulkarni, R. R.; Pawbake, A. S.; Waykar, R. G.; Rondiya, S. R.; Jadhavar, A. A.; Pandharkar, S. M.; Karpe, S. D.; Diwate, K. D.; Jadkar, S. R.

    2016-04-01

    Influence of deposition pressure on structural, morphology, electrical and optical properties of CdTe thin films deposited at low substrate temperature (100°C) by RF magnetron sputtering was investigated. The formation of CdTe was confirmed by low angle XRD and Raman spectroscopy. The low angle XRD analysis revealed that the CdTe films have zinc blende (cubic) structure with crystallites having preferred orientation in (111) direction. Raman spectra show the longitudinal optical (LO) phonon mode peak ˜ 165.4 cm-1 suggesting high quality CdTe film were obtained over the entire range of deposition pressure studied. Scanning electron microscopy analysis showed that films are smooth, homogenous, and crack-free with no evidence of voids. The EDAX data revealed that CdTe films deposited at low deposition pressure are high-quality stoichiometric. However, for all deposition pressures, films are rich in Cd relative to Te. The UV-Visible spectroscopy analysis show the blue shift in absorption edge with increasing the deposition pressure while the band gap show decreasing trend. The highest electrical conductivity was obtained for the film deposited at deposition pressure 1 Pa which indicates that the optimized deposition pressure for our sputtering unit is 1 Pa. Based on the experimental results, these CdTe films can be useful for the application in the flexible solar cells and other opto-electronic devices.

  7. Induced Recrystallization of CdTe Thin Films Deposited by Close-Spaced Sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H. R.; Dhere, R. G.; Al-Jassim, M. M.; Levi, D. H.; Kazmerski, L. L. (National Renewable Energy Laboratory); Mayo, B. (Southern University and A& M College, Baton Rouge, LA)

    1998-10-26

    We have deposited CdTe thin films by close-spaced sublimation at two different temperature ranges. The films deposited at the lower temperature partially recrystallized after CdCl2 treatment at 350 C and completely recrystallized after the same treatment at 400 C. The films deposited at higher temperature did not recrystallize at these two temperatures. These results confirmed that the mechanisms responsible for changes in physical properties of CdTe films treated with CdCl2 are recrystallization and grain growth, and provided an alternative method to deposit CSS films using lower temperatures.

  8. Induced recrystallization of CdTe thin films deposited by close-spaced sublimation

    Science.gov (United States)

    Moutinho, H. R.; Dhere, R. G.; Al-Jassim, M. M.; Mayo, B.; Levi, D. H.; Kazmerski, L. L.

    1999-03-01

    We have deposited CdTe thin films by close-spaced sublimation at two different temperature ranges. The films deposited at the lower temperature partially recrystallized after CdCl2 treatment at 350 °C and completely recrystallized after the same treatment at 400 °C. The films deposited at higher temperature did not recrystallize at these two temperatures. These results confirmed that the mechanisms responsible for changes in physical properties of CdTe films treated with CdCl2 are recrystallization and grain growth, and provided an alternative method to deposit CSS films using lower temperatures.

  9. Induced Recrystallization of CdTe Thin Films Deposited by Close-Spaced Sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H. R.; Dhere, R. G.; Al-Jassim, M. M.; Levi, D. H.; Kazmerski, L. L. (National Renewable Energy Laboratory); Mayo, B. (Southern University and A& M College, LA)

    1998-10-29

    We have deposited CdTe thin films by close-spaced sublimation at two different temperature ranges. The films deposited at the lower temperature partially recrystallized after CdCl{sub 2} treatment at 350 C and completely recrystallized after the same treatment at 400 C. The films deposited at higher temperature did not recrystallize at these two temperatures. These results confirmed that the mechanisms responsible for changes in physical properties of CdTe films treated with CdCl{sub 2} are recrystallization and grain growth, and provided an alternative method to deposit CSS films using lower temperatures.

  10. Comparative study of CdTe sources used for deposition of CdTe thin films by close spaced sublimation technique

    OpenAIRE

    Pinheiro,Wagner Anacleto; Falcão, Vivienne Denise; Cruz,Leila Rosa de Oliveira; Ferreira,Carlos Luiz

    2006-01-01

    Unlike other thin film deposition techniques, close spaced sublimation (CSS) requires a short source-substrate distance. The kind of source used in this technique strongly affects the control of the deposition parameters, especially the deposition rate. When depositing CdTe thin films by CSS, the most common CdTe sources are: single-crystal or polycrystalline wafers, powders, pellets or pieces, a thick CdTe film deposited onto glass or molybdenum substrate (CdTe source-plate) and a sintered C...

  11. Comparative study of CdTe sources used for deposition of CdTe thin films by close spaced sublimation technique

    Directory of Open Access Journals (Sweden)

    Wagner Anacleto Pinheiro

    2006-03-01

    Full Text Available Unlike other thin film deposition techniques, close spaced sublimation (CSS requires a short source-substrate distance. The kind of source used in this technique strongly affects the control of the deposition parameters, especially the deposition rate. When depositing CdTe thin films by CSS, the most common CdTe sources are: single-crystal or polycrystalline wafers, powders, pellets or pieces, a thick CdTe film deposited onto glass or molybdenum substrate (CdTe source-plate and a sintered CdTe powder. In this work, CdTe thin films were deposited by CSS technique from different CdTe sources: particles, powder, compact powder, a paste made of CdTe and propylene glycol and source-plates (CdTe/Mo and CdTe/glass. The largest deposition rate was achieved when a paste made of CdTe and propylene glycol was used as the source. CdTe source-plates led to lower rates, probably due to the poor heat transmission, caused by the introduction of the plate substrate. The results also showed that compacting the powder the deposition rate increases due to the better thermal contact between powder particles.

  12. Deposition of Cl-doped CdTe polycrystalline films by close-spaced sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Tamotsu; Takahashi, Kohei; Akiba, Sho; Yasuda, Nao [Department of Electrical and Electronic Engineering, National Institute of Technology, Kisarazu College, 2-11-1 Kiyomidai-higashi, Kisarazu, Chiba 292-0041 (Japan); Tokuda, Satoshi; Kishihara, Hiroyuki; Ichioka, Akina; Doki, Takahiro; Sato, Toshiyuki [Technology Research Laboratory, Shimadzu Corporation, 3-9-4 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan)

    2015-06-15

    The effects of Cl-doping on the CdTe layers by the close-spaced sublimation (CSS) deposition were investigated. Cl-doped CdTe polycrystalline films were deposited on graphite substrates by CSS method using a mixture of CdTe and CdCl{sub 2} powder as a source. In X-ray diffraction (XRD) patterns of the obtained films with various deposition times, many diffraction peaks other than CdTe peaks were observed in the deposition times lower than 10 min. These diffraction peaks were probably due to the formation of chlorides of Cd, Te and C, such as CdCl{sub 2}, TeCl{sub 4}, Te{sub 3}Cl{sub 2} and C{sub 10}Cl{sub 8}. X-ray fluorescence (XRF) and secondary ion mass spectrometry (SIMS) analyses revealed that a large amount of chlorine was contained in the films with the deposition times lower than 10 min, and that Cl concentration decreased with increasing the deposition time above 3 min. These results indicate that the films containing the chlorides of Cd, Te and C in addition to CdTe are formed in the initial stage of the CSS deposition using a mixture of CdTe and CdCl{sub 2} powder as a source. Cross-sectional images revealed that the grain size was decreased by the effect of Cl-doping. Furthermore, current-voltage (I -V) characteristics of the CdTe/graphite structures were measured, and it was found that the resistivity of the Cl-doped CdTe layer was much higher than that of the undoped CdTe layer. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Resistivity, carrier concentration, and carrier mobility of electrochemically deposited CdTe films

    OpenAIRE

    Takahashi, Makoto; Uosaki, Kohei; Kita, Hideaki; Yamaguchi, Shoji

    1986-01-01

    The electrical type, resistivity, and donor or acceptor concentration of CdTe films deposited electrochemically at various potentials were measured. The carrier mobilities of the films were determined from these results. The deposition potential dependence of the mobility was small and the deposition potential dependence of the resistivity was mainly controlled by the deposition potential dependence of the donor or acceptor concentration. The carrier mobilities were very small compared with t...

  14. Spray Deposition of High Quality CuInSe2 and CdTe Films: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Curtis, C. J.; van Hest, M.; Miedaner, A.; Leisch, J.; Hersh, P.; Nekuda, J.; Ginley, D. S.

    2008-05-01

    A number of different ink and deposition approaches have been used for the deposition of CuInSe2 (CIS), Cu(In,Ga)Se2 (CIGS), and CdTe films. For CIS and CIGS, soluble precursors containing Cu, In, and Ga have been developed and used in two ways to produce CIS films. In the first, In-containing precursor films were sprayed on Mo-coated glass substrates and converted by rapid thermal processing (RTP) to In2Se3. Then a Cu-containing film was sprayed down on top of the In2Se3 and the stacked films were again thermally processed to give CIS. In the second approach, the Cu-, In-, and Ga-containing inks were combined in the proper ratio to produce a mixed Cu-In-Ga ink that was sprayed on substrates and thermally processed to give CIGS films directly. For CdTe deposition, ink consisting of CdTe nanoparticles dispersed in methanol was prepared and used to spray precursor films. Annealing these precursor films in the presence of CdCl2 produced large-grained CdTe films. The films were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Optimized spray and processing conditions are crucial to obtain dense, crystalline films.

  15. A direct solution deposition approach to CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Miskin, Caleb K.; Dubois-Camacho, Angela; Reese, Matthew O.; Agrawal, Rakesh

    2016-01-01

    A direct solution deposition approach to CdTe thin films is presented. The difficulty of co-dissolving Te and desirable Cd salts is overcome through a diamine-thiol solvent mixture. Thin films of densely-packed, micron-sized grains are achieved after annealing without the need for chalcogen or CdCl2 vapor treatments.

  16. D. C. electrical properties of vacuum-deposited CdTe films

    Energy Technology Data Exchange (ETDEWEB)

    Gogoi, S.; Barua, K.

    1982-06-18

    The current-voltage characteristics of vacuum-deposited CdTe films were studied as a function of film thickness (2500-13 000 A) at various temperatures (0-110/sup 0/C). The d.c. conduction mechanism was explained using a modified Poole-Frenkel equation.

  17. Investigation of polycrystalline CdTe thin films deposited by physical vapor deposition, close-spaced sublimation, and sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Hasoon, F.S.; Abulfotuh, F.; Kazmerski, L.L. [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)

    1995-11-01

    CdTe thin films, deposited on different substrate structures by physical vapor deposition, sputtering, and close-spaced sublimation, have been treated with CdCl{sub 2} at several temperatures. The morphology of the films has been studied by atomic force microscopy, and the observations were correlated to results obtained from x-ray diffraction, cathodoluminescence, and minority-carrier lifetime measurements. The samples treated at 400 {degree}C resulted in the best device-quality films, independent of deposition method and underlying substrate structure. For the first time, a nanograin structure was observed in CdTe sputtered samples. copyright {ital 1995} {ital American} {ital Vacuum} {ital Society}.

  18. Influence of deposition parameters on the properties of CdTe films deposited by close spaced sublimation

    OpenAIRE

    Falcão Vivienne Denise; Pinheiro Wagner Anacleto; Ferreira Carlos Luiz; Cruz Leila Rosa de Oliveira

    2006-01-01

    CdTe thin films are used as absorber layer in CdS/CdTe solar cells. The microstructure of this absorber layer plays a fundamental role in photovoltaic conversion and can be controlled by the deposition parameters used during the film growth. In this work, CdTe thin films were deposited by the CSS method onto glass substrates previously covered with In2O3:Sn. The effects of pressure, source temperature and substrate temperature on the microstructural properties of the films were studied. The p...

  19. Induced recrystallization of CdTe thin films deposited by close-spaced sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Dhere, R.G.; Al-Jassim, M.M.; Levi, D.H.; Kazmerski, L.L. [National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States); Mayo, B. [Southern University and AM College, Harding Boulevard, Baton Rouge, Louisiana 70813 (United States)

    1999-03-01

    We have deposited CdTe thin films by close-spaced sublimation at two different temperature ranges. The films deposited at the lower temperature partially recrystallized after CdCl{sub 2} treatment at 350&hthinsp;{degree}C and completely recrystallized after the same treatment at 400&hthinsp;{degree}C. The films deposited at higher temperature did not recrystallize at these two temperatures. These results confirmed that the mechanisms responsible for changes in physical properties of CdTe films treated with CdCl{sub 2} are recrystallization and grain growth, and provided an alternative method to deposit CSS films using lower temperatures. {copyright} {ital 1999 American Institute of Physics.}

  20. Determination of dispersion parameters of thermally deposited CdTe thin film

    Science.gov (United States)

    Dhimmar, J. M.; Desai, H. N.; Modi, B. P.

    2016-05-01

    Cadmium Telluride (CdTe) thin film was deposited onto glass substrates under a vacuum of 5 × 10-6 torr by using thermal evaporation technique. The prepared film was characterized for dispersion analysis from reflectance spectra within the wavelength range of 300 nm - 1100 nm which was recorded by using UV-Visible spectrophotometer. The dispersion parameters (oscillator strength, oscillator wavelength, high frequency dielectric constant, long wavelength refractive index, lattice dielectric constant and plasma resonance frequency) of CdTe thin film were investigated using single sellimeir oscillator model.

  1. Effects of temperature and deposition time on the RF- sputtered CdTe films preparation

    OpenAIRE

    E. Camacho-Espinosa; Rosendo, E.; T. Díaz; A. I. Oliva; V. Rejon; Peña, J. L.

    2014-01-01

    In this work, CdTe thin films were deposited by rf-sputtering at different substrate temperatures (room temperature (RT), 100, 150, 200, and 250 °C) and deposition times (30, 60, and 90 min). The applied power and vacuum pressure were maintained fixed for all depositions. A mean value of 18 .5 nm/s on the deposition rate was maintained for films deposition. The surface morphology, rms-roughness, and grain size of the sputtered-films were obtained from atomic force microscopy and scanning elec...

  2. Three-dimensional defects in CdTe films obtained by pulsed laser deposition

    NARCIS (Netherlands)

    Sagan, P; Virt, IS; Zawislak, J; Rudyj, IO; Kuzma, M

    2004-01-01

    The quality of Cd chalcodenides epitaxial films can be enhanced seriously by applying a pulsed (electron beam or laser beam) method for ablation of targets. The structure of laser deposited CdTe layers was investigated by transmission high energy electron diffraction. This method is very useful for

  3. Physical properties of Bi-doped CdTe thin films deposited by cosputtering

    Energy Technology Data Exchange (ETDEWEB)

    Becerril, M.; Zelaya-Angel, O. [Departamento de Fisica, CINVESTAV-IPN, Apdo. Postal 14-740, 07000 Mexico D.F. (Mexico); Vigil-Galan, O.; Contreras-Puente, G.; Sanchez-Meza, E. [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, 07738 Mexico D.F. (Mexico)

    2007-03-15

    The structural, morphological, electrical, and optical properties of CdTe-Bi cosputtered thin films related with composition are presented. The films were grown on Corning glass substrates at room temperature from a CdTe-Bi target. The composition measurements show that the Bi content in the films ranges from x = 0.0 to x = 6.37 at%, depending on the area fraction covered by the Bi piece attached to the CdTe target. The structure of the annealed films was determined from X-ray diffraction measurements. Two kinds of structures were observed, depending on the Bi content: (1) CdTe polycrystalline films containing a small amount of Bi that is probably incorporated in the Cd and Te sites of the CdTe lattice. (2) Amorphization of the polycrystalline films, with higher Bi content. From the experimental results, we concluded that using this deposition method n/p-type Bi-doped CdTe polycrystalline films can be produced with electrical resistivity between 10{sup 2}-10{sup 3} {omega} cm and electron mobility between 10{sup 1} and 10{sup 2} cm{sup 2}V{sup -1}s{sup -1}. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Effects of various deposition times and RF powers on CdTe thin film growth using magnetron sputtering

    Science.gov (United States)

    Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

    2016-09-01

    Cadmium telluride (CdTe) is a p-type II-VI compound semiconductor, which is an active component for producing photovoltaic solar cells in the form of thin films, due to its desirable physical properties. In this study, CdTe film was deposited using the radio frequency (RF) magnetron sputtering system onto a glass substrate. To improve the properties of the CdTe film, effects of two experimental parameters of deposition time and RF power were investigated on the physical properties of the CdTe films. X-ray Diffraction (XRD), atomic force microscopy (AFM) and spectrophotometer were used to study the structural, morphological and optical properties of the CdTe samples grown at different experimental conditions, respectively. Our results suggest that film properties strongly depend on the experimental parameters and by optimizing these parameters, it is possible to tune the desired structural, morphological and optical properties. From XRD data, it is found that increasing the deposition time and RF power leads to increasing the crystallinity as well as the crystal sizes of the grown film, and all the films represent zinc blende cubic structure. Roughness values given from AFM images suggest increasing the roughness of the CdTe films by increasing the RF power and deposition times. Finally, optical investigations reveal increasing the film band gaps by increasing the RF power and the deposition time.

  5. Radiative recombination mechanisms in CdTe thin films deposited by elemental vapor transport

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Shamara [Department of Electrical Engineering, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620 (United States); Vatavu, Sergiu, E-mail: svatavu@usm.md [Department of Electrical Engineering, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620 (United States); Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., Chisinau, MD-2009, Republic of Moldova (Moldova, Republic of); Evani, Vamsi; Khan, Md; Bakhshi, Sara; Palekis, Vasilios [Department of Electrical Engineering, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620 (United States); Rotaru, Corneliu [Faculty of Physics and Engineering, Moldova State University, 60 A. Mateevici str., Chisinau, MD-2009, Republic of Moldova (Moldova, Republic of); Ferekides, Chris [Department of Electrical Engineering, University of South Florida, 4202 East Fowler Ave, Tampa, FL 33620 (United States)

    2015-05-01

    A photoluminesence (PL) study of the radiative recombination mechanisms for CdTe films deposited under different Cd and Te overpressure by elemental vapor transport is presented. The experiment and analysis have been carried out in the temperature range of 12-130 K. The intensity of the PL laser excitation beam was varied by two orders of magnitude. It has been established that the bands in the 1.47-1.50 eV are determined by transitions involving shallow D and A states and the 1.36x-1.37x eV band is due to band to level transitions. Deep transitions at 1.042 eV and 1.129 eV are due to radiative transitions to levels determined by CdTe native defects. - Highlights: • Photoluminescense (PL) of CdTe thin films is present in the 0.8-1.6 eV spectral region. • High intensity excitonic peaks are among the main radiative paths. • Radiative transitions at 1.36x eV are assisted by dislocations caused levels. • Extremal Cd/Te overpressure ratios enhance PL for 1.497 eV, 1.486 eV, 1.474 eV bands. • PL intensity reaches its max value for the 0.45 and 1.25 Cd/Te overpressure ratios.

  6. Deposition of CdTe films under microgravity: Foton M3 mission

    Energy Technology Data Exchange (ETDEWEB)

    Benz, K.W.; Croell, A. [Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universitaet Freiburg (Germany); Zappettini, A.; Calestani, D. [CNR Parma, Instituto Materiali Speciali per Elettronica e Magnetismo IMEM, Fontani Parma (Italy); Dieguez, E. [Universidad Autonoma de Madrid (Spain). Departamento de Fisica de Materiales; Carotenuto, L.; Bassano, E. [Telespazio Napoli, Via Gianturco 31, 80146 Napoli (Italy); Fiederle, M.

    2009-10-15

    Experiments of deposition of CdTe films have been carried out under microgravity in the Russian Foton M3 mission. The influence of gravity has been studied with these experiments and compared to the results of simulations. The measured deposition rate could be confirmed by the theoretical results for lower temperatures. For higher temperatures the measured thickness of the deposited films was larger compared to the theoretical data. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Influence of deposition parameters on the properties of CdTe films deposited by close spaced sublimation

    Directory of Open Access Journals (Sweden)

    Vivienne Denise Falcão

    2006-03-01

    Full Text Available CdTe thin films are used as absorber layer in CdS/CdTe solar cells. The microstructure of this absorber layer plays a fundamental role in photovoltaic conversion and can be controlled by the deposition parameters used during the film growth. In this work, CdTe thin films were deposited by the CSS method onto glass substrates previously covered with In2O3:Sn. The effects of pressure, source temperature and substrate temperature on the microstructural properties of the films were studied. The properties were mainly influenced by the pressure, the presence of oxygen in the reaction chamber, and the substrate temperature. For films deposited under an argon atmosphere, an increase in grain size and a reduction of the texture were observed as the pressure and substrate temperature were increased. The introduction of oxygen in the atmosphere led to a decrease in the deposition rate and affected the microstructure and composition of the film. Films deposited under an argon-oxygen atmosphere have smaller grains than those deposited under argon and are richer in Te. The addition of oxygen to the atmosphere apparently did not result in the formation of oxides.

  8. Thin-film CdTe photovoltaic cells by laser deposition and rf sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A.; Bohn, R.G.; Bhat, A.; Tabory, C.; Shao, M.; Li, Y.; Savage, M.E.; Tsien, L. (Department of Physics and Astronomy, The University of Toledo, Toledo, Ohio 43606 (United States))

    1992-12-01

    Laser-driven physical vapor deposition (LDPVD) and radio-frequency (rf) sputtering have been used to fabricate thin-film solar cells on SnO[sub 2]-coated glass substrates. The laser-ablation process readily permits the use of several target materials in the same vacuum chamber and complete solar cell structures have been fabricated on SnO[sub 2]-coated glass using LDPVD for the CdS, CdTe, and CdCl[sub 2]. To date the best devices ([similar to]9% AM1.5) have been obtained after a post-deposition anneal at 400 [degree]C. In addition, cells have been fabricated with the combination of LDPVD CdS, rf-sputtered CdTe, and LDPVD CdCl[sub 2]. The performance of these cells indicates considerable promise for the potential of rf sputtering for CdTe photovoltaic devices. The physical mechanisms of LDPVD have been studied by transient optical spectroscopy on the laser ablation plume. These measurements have shown that, e.g., Cd is predominantly in the neutral atomic state in the plume but with a large fraction which is highly excited internally ([ge]6 eV) and that the typical neutral Cd translational kinetic energies perpendicular to the target are 20 eV and greater. Quality of as-grown and annealed films has been analyzed by optical absorption. Raman scattering, photoluminescence, electrical conductivity, Hall effect, x-ray diffraction, and SEM/EDS.

  9. Microcharacterization of CdTe films deposited by close-spaced sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Matson, R.J.; Hasoon, F.S.; Jones, K.M.; Al-Jassim, M.M. (National Renewable Energy Lab., Golden, CO (United States)); Tomlinson, R.D. (Salford Univ. (United Kingdom))

    1994-07-01

    Microcharacterization of the luminescent, structural, electrical and topographical properties of thin films of close-spaced sublimation (CSS)-fabricated CdTe was performed. The film morphology was found to be dependent on the film thickness, deposition conditions and post-deposition treatment. The complementary use of electron beam-induced current (EBIC) and cathodoluminescence (CL) analysis in the scanning electron microscope demonstrated large inter- and intragrain inhomogeneities in the luminescent and electrical properties of the films. Follow-on plan-view examinations with the transmission electron microscope revealed varying densities of structural defects, such as stacking faults and threading dislocations, which could explain the variations observed in the CL and EBIC images. (author)

  10. Physical properties of spray deposited CdTe thin films: PEC performance

    Institute of Scientific and Technical Information of China (English)

    V. M. Nikale; S. S. Shinde; C. H. Bhosale; K.Y. Rajpure

    2011-01-01

    p-CdTe thin films were prepared by spray pyrolysis under different ambient conditions and characterized using photoelectrochemical (PEC),X-ray diffraction (XRD),scanning electron microscopy,energy-dispersive analysis by X-ray (EDAX),and optical transmission studies.The different preparative parameters viz solution pH,solution quantity,substrate temperature and solution concentration have been optimized by the PEC technique in order to get good-quality photosensitive material.XRD analysis shows the polycrystalline nature of the film,having cubic structure with strong (111) orientation.Micrographs reveal that grains are uniformly distributed over the surface of the substrate indicating the well-defined growth ofpolycrystalline CdTe thin film.The EDAX study for the sample deposited at optimized preparative parameters shows the nearly stoichiometric Cd:Te ratio.Optical absorption shows the presence of direct transition with band gap energy of 1.5 eV.Deposited films exhibit the highest photocurrent of 2.3 mA,a photovoltage of 462 mV,a 0.48 fill factor and 3.4% efficiency for the optimized preparative parameters.

  11. The study of properties of CdTe thin films deposited in Ar/O{{2}} atmosphere

    Science.gov (United States)

    Li, Y.; Li, B.; Feng, L.; Zheng, J.; Li, W.

    2009-02-01

    The preparation and properties of CdTe thin films is of a primary interest for the CdTe thin film solar cells in both research and technology. In our work, polycrystalline CdTe thin films were deposited on pretreated glass substrates in Ar/O{2} atmosphere by closed-space sublimation (CSS) technology. Structural property was studied by X-ray diffraction (XRD), surface morphology was observed by scanning electron microscopy (SEM). The optical and electrical properties of CdTe films were investigated, as well as the effects of deposition temperatures, the ratio of gas (Ar/O{2}) and post-treatment on the properties. The high quality CdTe layer was prepared based on the above studies. These layers were used to prepared CdS/CdTe/ZnTe:Cu solar cells. Efficiency of 13.38% and fill factor of 70.3% (0.501 cm2 area) for CdTe solar cells have been achieved. Project supported by the National High Technology Research and Development Program of China (Grant No.2003AA513010) and the National Natural Science Foundation of China (Grant No.60506004).

  12. Physical properties of vacuum evaporated CdTe thin films with post-deposition thermal annealing

    Science.gov (United States)

    Chander, Subhash; Dhaka, M. S.

    2015-09-01

    This paper presents the physical properties of vacuum evaporated CdTe thin films with post-deposition thermal annealing. The thin films of thickness 500 nm were grown on glass and indium tin oxide (ITO) coated glass substrates employing thermal vacuum evaporation technique followed by post-deposition thermal annealing at temperature 450 °C. These films were subjected to the X-ray diffraction (XRD),UV-Vis spectrophotometer, source meter and atomic force microscopy (AFM) for structural, optical, electrical and surface morphological analysis respectively. The X-ray diffraction patterns reveal that the films have zinc-blende structure of single cubic phase with preferred orientation (111) and polycrystalline in nature. The crystallographic and optical parameters are calculated and discussed in brief. The optical band gap is found to be 1.62 eV and 1.52 eV for as-grown and annealed films respectively. The I-V characteristics show that the conductivity is decreased for annealed thin films. The AFM studies reveal that the surface roughness is observed to be increased for thermally annealed films.

  13. Structural and optical properties of Cu-doped CdTe films with hexagonal phase grown by pulsed laser deposition

    Directory of Open Access Journals (Sweden)

    F. de Moure-Flores

    2012-06-01

    Full Text Available Cu-doped CdTe thin films were prepared by pulsed laser deposition on Corning glass substrates using powders as target. Films were deposited at substrate temperatures ranging from 100 to 300 °C. The X-ray diffraction shows that both the Cu-doping and the increase in the substrate temperature promote the presence of the hexagonal CdTe phase. For a substrate temperature of 300 °C a CdTe:Cu film with hexagonal phase was obtained. Raman and EDS analysis indicate that the films grew with an excess of Te, which indicates that CdTe:Cu films have p-type conductivity.

  14. Atmospheric pressure chemical vapor deposition of CdTe for high efficiency thin film PV devices: Annual subcontract report, 26 January 1999--25 January 2000

    Energy Technology Data Exchange (ETDEWEB)

    Meyers, P. V.; Kee, R.; Wolden, C.; Kestner, J.; Raja, L.; Kaydanov, V.; Ohno, T.; Collins, R.; Fahrenbruch, A.

    2000-05-30

    ITN's three year project Atmospheric Pressure Chemical Vapor Deposition (APCVD) of CdTe for High Efficiency Thin Film PV Devices has the overall objectives of improving thin film CdTe PV manufacturing technology and increasing CdTe PV device power conversion efficiency. CdTe deposition by APCVD employs the same reaction chemistry as has been used to deposit 16% efficient CdTe PV films, i.e., close spaced sublimation, but employs forced convection rather than diffusion as a mechanism of mass transport. Tasks of the APCVD program center on demonstration of APCVD of CdTe films, discovery of fundamental mass transport parameters, application of established engineering principles to the deposition of CdTe films, and verification of reactor design principles which could be used to design high throughput, high yield manufacturing equipment. Additional tasks relate to improved device measurement and characterization procedures that can lead to a more fundamental understanding of CdTe PV device operation and ultimately to higher device conversion efficiency and greater stability. Under the APCVD program, device analysis goes beyond conventional one-dimensional device characterization and analysis toward two dimension measurements and modeling. Accomplishments of the second year of the APCVD subcontract include: deposition of the first APCVD CdTe; identification of deficiencies in the first generation APCVD reactor; design, fabrication and testing of a ``simplified'' APCVD reactor; deposition of the first dense, adherent APCVD CdTe films; fabrication of the first APCVD CdTe PV device; modeling effects of CdSTe and SnOx layers; and electrical modeling of grain boundaries.

  15. Structural reproducibility of CdTe thin films deposited on different substrates by close space sublimation method

    Energy Technology Data Exchange (ETDEWEB)

    Potlog, T.; Spalatu, N.; Maticiuc, N. [Physics Department, Moldova State University, Chisinau (Moldova); Hiie, J.; Valdna, V.; Mikli, V.; Mere, A. [Department of Materials Science, Tallinn University of Technology, Tallinn (Estonia)

    2012-02-15

    We report on the characterization of polycrystalline CdTe thin films grown directly on glass, SnO{sub 2}-coated glass, and CdS/SnO{sub 2}/glass at relatively low temperatures by employing the close space sublimation technique (CSS). The deposited films have been characterized by using optical absorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Based on the SEM and optical analysis, the CdTe/CdS/SnO{sub 2}/glass thin films exhibit a superior crystal quality and reproducibility in comparison to other CdTe films grown on glass and SnO{sub 2}/glass. XRD study reveals that films are polycrystalline with a cubic crystal structure. The EDX characterization indicates that all CdTe thin films are nearly stoichiometric. The optical absorption study shows a larger variation of band gap from 1.485 to 1.495 eV for CdTe grown on SnO{sub 2}-coated glass. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Effect of Substrate Temperature on Structural and Optical Properties of Nanocrystalline CdTe Thin Films Deposited by Electron Beam Evaporation

    OpenAIRE

    M. Rigana Begam; N. Madhusudhana Rao; S. Kaleemulla; M. Shobana; N. Sai Krishna; M. Kuppan

    2013-01-01

    Nanocrystalline Cadmium Telluride (CdTe) thin films were deposited onto glass substrates using electron beam evaporation technique. The effect of substrate temperature on the structural, morphological and optical properties of CdTe thin films has been investigated. All the CdTe films exhibited zinc blende structure with (111) preferential orientation. The crystallite size of the films increased from 35 nm to 116 nm with the increase of substrate temperature and the band gap of the films decre...

  17. Effect of Substrate Temperature on Structural and Optical Properties of Nanocrystalline CdTe Thin Films Deposited by Electron Beam Evaporation

    Directory of Open Access Journals (Sweden)

    M. Rigana Begam

    2013-07-01

    Full Text Available Nanocrystalline Cadmium Telluride (CdTe thin films were deposited onto glass substrates using electron beam evaporation technique. The effect of substrate temperature on the structural, morphological and optical properties of CdTe thin films has been investigated. All the CdTe films exhibited zinc blende structure with (111 preferential orientation. The crystallite size of the films increased from 35 nm to 116 nm with the increase of substrate temperature and the band gap of the films decreased from 2.87 eV to 2.05 eV with the increase of the crystallite size.

  18. CdTe thin film solar cells produced using a chamberless inline process via metalorganic chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kartopu, G., E-mail: giray.kartopu@glyndwr.ac.uk; Barrioz, V.; Monir, S.; Lamb, D.A.; Irvine, S.J.C.

    2015-03-02

    Cd{sub 1−x}Zn{sub x}S and CdTe:As thin films were deposited using a recently developed chamberless inline process via metalorganic chemical vapour deposition (MOCVD) at atmospheric pressure and assessed for fabrication of CdTe photovoltaic (PV) solar cells. Initially, CdS and Cd{sub 1−x}Zn{sub x}S coatings were applied onto 15 × 15 cm{sup 2} float glass substrates, characterised for their optical properties, and then used as the window layer in CdTe solar cells which were completed in a conventional MOCVD (batch) reactor. Such devices provided best conversion efficiency of 13.6% for Cd{sub 0.36}Zn{sub 0.64}S and 10% for CdS which compare favourably to the existing baseline MOCVD (batch reactor) devices. Next, sequential deposition of Cd{sub 0.36}Zn{sub 0.64}S and CdTe:As films was realised by the chamberless inline process. The chemical composition of a 1 μm CdTe:As/150 nm Cd{sub 0.36}Zn{sub 0.64}S bi-layer was observed via secondary ions mass spectroscopy, which showed that the key elements are uniformly distributed and the As doping level is suitable for CdTe device applications. CdTe solar cells formed using this structure provided a best efficiency of 11.8% which is promising for a reduced absorber thickness of 1.25 μm. The chamberless inline process is non-vacuum, flexible to implement and inherits from the legacy of MOCVD towards doping/alloying and low temperature operation. Thus, MOCVD enabled by the chamberless inline process is shown to be an attractive route for thin film PV applications. - Highlights: • CdS, CdZnS and CdTe thin films grown by a chamberless inline process • The inline films assessed for fabricating CdTe solar cells • 13.6% conversion efficiency obtained for CdZnS/CdTe cells.

  19. The large-area CdTe thin film for CdS/CdTe solar cell prepared by physical vapor deposition in medium pressure

    Science.gov (United States)

    Luo, Run; Liu, Bo; Yang, Xiaoyan; Bao, Zheng; Li, Bing; Zhang, Jingquan; Li, Wei; Wu, Lili; Feng, Lianghuan

    2016-01-01

    The Cadmium telluride (CdTe) thin film has been prepared by physical vapor deposition (PVD), the Ar + O2 pressure is about 0.9 kPa. This method is a newer technique to deposit CdTe thin film in large area, and the size of the film is 30 × 40 cm2. This method is much different from the close-spaced sublimation (CSS), as the relevance between the source temperature and the substrate temperature is weak, and the gas phase of CdTe is transferred to the substrate by Ar + O2 flow. Through this method, the compact and uniform CdTe film (30 × 40 cm2) has been achieved, and the performances of the CdTe thin film have been determined by transmission spectrum, SEM and XRD. The film is observed to be compact with a good crystallinity, the CdTe is polycrystalline with a cubic structure and a strongly preferred (1 1 1) orientation. Using the CdTe thin film (3 × 5 cm2) which is taken from the deposited large-area film, the 14.6% efficiency CdS/CdTe thin film solar cell has been prepared successfully. The structure of the cell is glass/FTO/CdS/CdTe/graphite slurry/Au, short circuit current density (Jsc) of the cell is 26.9 mA/cm2, open circuit voltage (Voc) is 823 mV, and filling factor (FF) is 66.05%. This technique can be a quite promising method to apply in the industrial production, as it has great prospects in the fabricating of large-area CdTe film.

  20. Influence of post-deposition heat treatment on optical properties derived from UV–vis of cadmium telluride (CdTe) thin films deposited on amorphous substrate

    Energy Technology Data Exchange (ETDEWEB)

    Punitha, K. [Department of Physics, Alagappa University, Karaikudi 630004 (India); Sivakumar, R., E-mail: krsivakumar1979@yahoo.com [Directorate of Distance Education, Alagappa University, Karaikudi 630004 (India); Sanjeeviraja, C. [Department of Physics, Alagappa Chettiar College of Engineering and Technology, Karaikudi 630004 (India); Ganesan, V. [UGC-DAE Consortium for Scientific Research, Indore 452001 (India)

    2015-07-30

    Graphical abstract: - Highlights: • Annealing-induced change in optical parameters of CdTe film was derived from UV–vis study. • Optical constants of the films were evaluated using Swanepoel method. • Dispersion energy data obeyed the single oscillator of the Wemple−Didomenico model. • Cd deficiency of the film confirmed the p-type conductive nature. - Abstract: In this work, we report on post-deposition heat treatment (annealing)-induced change in optical properties derived from UV–vis study of CdTe thin films prepared on amorphous glass substrate by electron beam evaporation technique. Annealing effect gives rise to the enhancement in crystalline nature (zinc blende structure) of CdTe films with (1 1 1) preferred orientation. The average transmittance was increased with the annealing temperature and the slight shift in transmission threshold towards higher wavelength region revealed the systematic reduction in optical energy band gap. The existence of shallow level just below the conduction band, within the band gap was identified in the range of 0.23 and 0.14 eV for the films annealed at 200 and 450 °C, respectively. The optical quality of deposited films was confirmed by the photoluminescence study. In addition, the scanning electron microscopic measurement supports the result of X-ray diffraction study. The Swanepoel, Hervé-Vandamme, and Wemple−DiDomenico models have been employed to evaluate the various optical parameters of CdTe films. These results are correlated well with other physical properties and discussed with the possible concepts underlying the phenomena.

  1. Characterization of CdTe films with in situ CdCl{sub 2} treatment grown by a simple vapor phase deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Rios Flores, Araceli, E-mail: arios@mda.cinvestav.mx [Applied Physics Department, CINVESTAV-IPN Merida, C.P. 97310 Merida, Yucatan (Mexico); Castro-Rodriguez, R.; Pena, J.L. [Applied Physics Department, CINVESTAV-IPN Merida, C.P. 97310 Merida, Yucatan (Mexico); Romeo, N.; Bosio, A. [Dipartimento di fisica, Universita di Parma, Campus Universitario, Parco Area delle Scienza, 43100 Parma (Italy)

    2009-05-15

    A unique vapor phase deposition (VPD) technique was designed and built to achieve in situ CdCl{sub 2} treatment of CdTe film. The substrate temperature was 400 deg. C, and the temperature of CdTe mixture with CdCl{sub 2} source was 500 deg. C. The structural and morphological properties of CdTe have been studied as a function of wt.% CdCl{sub 2} concentration by using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). XRD measurements show that the presence of CdCl{sub 2} vapor induces (1 1 1)-oriented growth in the CdTe film. SEM measurements have shown enhance growth of grains, in the presence of CdCl{sub 2}. From AFM the roughness of the films showed a heavy dependence on CdCl{sub 2} concentration. In the presence of 4% CdCl{sub 2} concentration, the CdTe films roughness has a root mean square (rms) value of about 275 A. This value is about 831 A for the non-treated CdTe films.

  2. Characterization of CdTe films with in situ CdCl 2 treatment grown by a simple vapor phase deposition technique

    Science.gov (United States)

    Flores, Araceli Rios; Castro-Rodríguez, R.; Peña, J. L.; Romeo, N.; Bosio, A.

    2009-05-01

    A unique vapor phase deposition (VPD) technique was designed and built to achieve in situ CdCl 2 treatment of CdTe film. The substrate temperature was 400 °C, and the temperature of CdTe mixture with CdCl 2 source was 500 °C. The structural and morphological properties of CdTe have been studied as a function of wt.% CdCl 2 concentration by using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). XRD measurements show that the presence of CdCl 2 vapor induces (1 1 1)-oriented growth in the CdTe film. SEM measurements have shown enhance growth of grains, in the presence of CdCl 2. From AFM the roughness of the films showed a heavy dependence on CdCl 2 concentration. In the presence of 4% CdCl 2 concentration, the CdTe films roughness has a root mean square (rms) value of about 275 Å. This value is about 831 Å for the non-treated CdTe films.

  3. Influence of plasma parameters and substrate temperature on the structural and optical properties of CdTe thin films deposited on glass by laser ablation

    Energy Technology Data Exchange (ETDEWEB)

    Quiñones-Galván, J. G.; Santana-Aranda, M. A.; Pérez-Centeno, A. [Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, Guadalajara, Jalisco C.P. 44430 (Mexico); Camps, Enrique [Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, D.F., C.P. 11801 (Mexico); Campos-González, E.; Guillén-Cervantes, A.; Santoyo-Salazar, J.; Zelaya-Angel, O. [Departamento de Física, CINVESTAV-IPN, Apartado Postal 14-740, D. F. C.P. 07360 (Mexico); Hernández-Hernández, A. [Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de Chimalpa Tlalayote s/n Colonia Chimalpa, Apan Hidalgo (Mexico); Moure-Flores, F. de [Facultad de Química, Materiales, Universidad Autónoma de Querétaro, Querétaro C.P. 76010 (Mexico)

    2015-09-28

    In the pulsed laser deposition of thin films, plasma parameters such as energy and density of ions play an important role in the properties of materials. In the present work, cadmium telluride thin films were obtained by laser ablation of a stoichiometric CdTe target in vacuum, using two different values for: substrate temperature (RT and 200 °C) and plasma energy (120 and 200 eV). Structural characterization revealed that the crystalline phase can be changed by controlling both plasma energy and substrate temperature; which affects the corresponding band gap energy. All the thin films showed smooth surfaces and a Te rich composition.

  4. High-efficiency CdTe thin-film solar cells using metalorganic chemical vapor deposition techniques

    Science.gov (United States)

    Nouhi, A.; Stirn, R. J.; Meyers, P. V.; Liu, C. H.

    1989-01-01

    Energy conversion efficiency of metalorganic chemical vapor deposited CdTe as an intrinsic active layer in n-i-p solar cell structures is reported. Small-area devices with efficiencies over 9 percent have been demonstrated. I-V characteristics, photospectral response, and the results of Auger profiling of structural composition for typical devices will be presented. Also presented are preliminary results on similar photovoltaic devices having Cd(0.85)Mn(0.15)Te in place of CdTe as an i layer.

  5. Electrochemical Deposition of CdTe Semiconductor Thin Films for Solar Cell Application Using Two-Electrode and Three-Electrode Configurations: A Comparative Study

    Directory of Open Access Journals (Sweden)

    O. K. Echendu

    2016-01-01

    Full Text Available Thin films of CdTe semiconductor were electrochemically deposited using two-electrode and three-electrode configurations in potentiostatic mode for comparison. Cadmium sulphate and tellurium dioxide were used as cadmium and tellurium sources, respectively. The layers obtained using both configurations exhibit similar structural, optical, and electrical properties with no specific dependence on any particular electrode configuration used. These results indicate that electrochemical deposition (electrodeposition of CdTe and semiconductors in general can equally be carried out using two-electrode system as well as the conventional three-electrode system without compromising the essential qualities of the materials produced. The results also highlight the advantages of the two-electrode configuration in process simplification, cost reduction, and removal of a possible impurity source in the growth system, especially as the reference electrode ages.

  6. High-quality CdTe films from nanoparticle precursors

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, D.L.; Pehnt, M.; Urgiles, E. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    In this paper the authors demonstrate that nanoparticulate precursors coupled with spray deposition offers an attractive route into electronic materials with improved smoothness, density, and lower processing temperatures. Employing a metathesis approach, cadmium iodide was reacted with sodium telluride in methanol solvent, resulting in the formation of soluble NaI and insoluble CdTe nanoparticles. After appropriate chemical workup, methanol-capped CdTe colloids were isolated. CdTe thin film formation was achieved by spray depositing the nanoparticle colloids (25-75 {Angstrom} diameter) onto substrates at elevated temperatures (T = 280-440{degrees}C) with no further thermal treatment. These films were characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Cubic CdTe phase formation was observed by XRD, with a contaminant oxide phase also detected. XPS analysis showed that CdTe films produced by this one-step method contained no Na or C and substantial O. AFM gave CdTe grain sizes of {approx}0.1-0.3 {mu}m for film sprayed at 400{degrees}C. A layer-by-layer film growth mechanism proposed for the one-step spray deposition of nanoparticle precursors will be discussed.

  7. Effect of the CdCl2 Treatment on the Morphology and Structural Properties of CdTe Thin Films Deposited by the CSS Method

    Science.gov (United States)

    Infante, H.; Gordillo, G.

    CdTe thin films deposited by the CSS (close spaced sublimation) method, with adequate properties to be used as absorber layer in solar cells, were submitted to a chemical treatment in a saturated CdCl2 solution, followed by thermal annealing in air at 400°C, in order to improve the electronic properties. The effect of chemical and thermal treatments on the morphological and crystallographic properties was studied through atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements. The studies revealed that the CdTe grows in the cubic phase and that the postdeposition treatments affect the morphology as well as the crystallographic properties; the effect on the morphology is significantly stronger. Increase of the grain size and roughness was observed in samples treated chemically and thermally. On the other hand, no effects were identified on the crystalline structure as induced by the treatments, although recrystallization was observed after thermal annealing.

  8. Recent advances in thin film CdTe solar cells

    Science.gov (United States)

    Ferekides, Chris S.; Ceekala, Vijaya; Dugan, Kathleen; Killian, Lawrence; Oman, Daniel; Swaminathan, Rajesh; Morel, Don

    1996-01-01

    CdTe thin film solar cells have been fabricated on a variety of glass substrates (borosilicate and soda lime). The CdS films were deposited to a thickness of 500-2000 Å by the chemical bath deposition (CBD), rf sputtering, or close spaced sublimation (CSS) processes. The CdTe films were deposited by CSS in the temperature range of 450-625 °C. The main objective of this work is to fabricate high efficiency solar cells using processes that can meet low cost manufacturing requirements. In an attempt to enhance the blue response of the CdTe cells, ZnS films have also been prepared (CBD, rf sputtering, CSS) as an alternative window layer to CdS. Device behavior has been found to be consistent with a recombination model.

  9. Comparative study of Hg xCd 1-xTe films grown on CdTe thin films previously deposited from two different techniques

    Science.gov (United States)

    Ali, A.; Abbas Shah, N.; Maqsood, A.

    2009-04-01

    High quality cadmium telluride (CdTe) thin films were grown on glass substrates with two different techniques, two evaporation source (TES) and closed space sublimation (CSS). Further to the above mercury telluride (HgTe) was then deposited by using single source on both CdTe thin films for obtaining Hg xCd 1-xTe samples. The crystalline structure of the Hg xCd 1-xTe sample grown from CSS-CdTe showed the preferential (1 1 1) orientation with smoother and larger grain size than those of TES-CdTe. The optical transmission for TES-CdTe sample was above 90% in the 1000-1500 nm range whereas it was significantly below 80% for CSS-CdTe sample. The optical transmission for TES-Hg xCd 1-xTe and CSS-Hg xCd 1-xTe was ˜60%. The resistivity at room temperature of TES-CdTe and CSS-CdTe was ˜3.33×10 9 Ω cm and ˜2.20×10 8 Ω cm, respectively, while the resistivity of TES-Hg xCd 1-xTe and CSS-Hg xCd 1-xTe samples was ˜1.73 Ω cm and ˜5.34×10 5 Ω cm, respectively. The comparative study of ternary compound prepared with the above techniques has been carried out for the first time.

  10. Fractal features of CdTe thin films grown by RF magnetron sputtering

    Science.gov (United States)

    Hosseinpanahi, Fayegh; Raoufi, Davood; Ranjbarghanei, Khadijeh; Karimi, Bayan; Babaei, Reza; Hasani, Ebrahim

    2015-12-01

    Cadmium telluride (CdTe) thin films were prepared by RF magnetron sputtering on glass substrates at room temperature (RT). The film deposition was performed for 5, 10, and 15 min at power of 30 W with a frequency of 13.56 MHz. The crystal structure of the prepared CdTe thin films was studied by X-ray diffraction (XRD) technique. XRD analyses indicate that the CdTe films are polycrystalline, having zinc blende structure of CdTe irrespective of their deposition time. All CdTe films showed a preferred orientation along (1 1 1) crystalline plane. The surface morphology characterization of the films was studied using atomic force microscopy (AFM). The quantitative AFM characterization shows that the RMS surface roughness of the prepared CdTe thin films increases with increasing the deposition time. The detrended fluctuation analysis (DFA) and also multifractal detrended fluctuation analysis (MFDFA) methods showed that prepared CdTe thin films have multifractal nature. The complexity, roughness of the CdTe thin films and strength of the multifractality increase as deposition time increases.

  11. Effect of CdCl{sub 2} treatment on structural and electronic property of CdTe thin films deposited by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M.A. [Solar Energy Research Institute (SERI), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Hossain, M.S.; Aliyu, M.M. [Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Karim, M.R. [Center of Excellence for Research in Engineering Materials (CEREM) College of Engineering, King Saud University, Riyadh, 11421 (Saudi Arabia); Razykov, T.; Sopian, K. [Solar Energy Research Institute (SERI), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Amin, N., E-mail: nowshad@eng.ukm.my [Solar Energy Research Institute (SERI), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Center of Excellence for Research in Engineering Materials (CEREM) College of Engineering, King Saud University, Riyadh, 11421 (Saudi Arabia)

    2013-11-01

    The structural and electrical properties of the magnetron sputtered CdTe thin films with subsequent CdCl{sub 2} solution treatment have been studied with a major focus on the influence of CdCl{sub 2} treatment to achieve high quality thin films. In this study, CdTe films with a thickness of 1.5 to 2 μm have been grown using the magnetron sputtering technique on top of glass substrate at an optimized substrate temperature of 250 °C. Aqueous CdCl{sub 2} concentration varied from 0.3 mol to 1.2 mol with the annealing temperature from 360 °C to 450 °C. The surface roughness of the films increases with the increase of solution concentration, while it fluctuates with the increase of annealing temperature. The density of nucleation centers and the strain increases for the films treated at 360 °C with 0.3 M to1.2 M while the grain growth of the films reduces. However, these strains are released at higher annealing temperatures, resulting in reduced dislocation densities, structural defects as well as increased crystalline property and grain size. The carrier concentration increases with the increase of treated CdCl{sub 2} concentration and subsequent annealing temperature. The highest carrier concentration of 1.05 × 10{sup 14}/cm{sup 3} was found for the CdTe thin films treated with 0.3 M CdCl{sub 2} solution followed by an annealing treatment at 420 °C for 20 min. - Highlights: • CdTe thin films are grown as absorption layers in CdTe solar cells by sputtering. • CdTe film quality in terms of structural and electronic properties is examined. • All growth parameters are optimized in the range of 1.5 to 2 μm CdTe films.

  12. Preparation and characterization of pulsed laser deposited a novel CdS/CdSe composite window layer for CdTe thin film solar cell

    Science.gov (United States)

    Yang, Xiaoyan; Liu, Bo; Li, Bing; Zhang, Jingquan; Li, Wei; Wu, Lili; Feng, Lianghuan

    2016-03-01

    A novel CdS/CdSe composite window structure was designed and then the corresponding films were prepared by pulsed laser deposition as an improved window layer for CdTe-based solar cells. Two types of this composite window structure with 5 cycles and 10 cycles CdS/CdSe respectively both combined with CdS layers were prepared at 200 °C compared with pure CdS window layer and finally were applied into CdTe thin film solar cells. The cross section and surface morphology of the two composite window layers were monitored by using scanning electron microscopy and the result shows that the pulsed laser deposited composite window layers with good crystallinity are stacking together as the design. The devices based on CdS/CdSe composite window layers have demonstrated the enhanced photocurrent collection from both short and long wavelength regions compared to CdS/CdTe solar cell. The efficiency of the best reference CdS/CdTe solar cell was 10.72%. And the device with 5 cycles CdS/CdSe composite window showed efficiency of 12.61% with VOC of 772.92 mV, JSC of 25.11 mA/cm2 and FF of 64.95%. In addition, there are some differences which exist within the optical transmittance spectra and QE curves between the two CdS/CdSe composite window samples, indicating that the volume proportion of CdSe may influence the performance of CdTe thin film solar cell.

  13. Effects of Various RF Powers on CdTe Thin Film Growth Using RF Magnetron Sputtering

    Science.gov (United States)

    Alibakhshi, Mohammad; Ghorannevis, Zohreh

    2016-09-01

    Cadmium telluride (CdTe) film was deposited using the magnetron sputtering system onto a glass substrate at various deposition times and radio frequency (RF) powers. Ar gas was used to generate plasma to sputter the CdTe atoms from CdTe target. Effects of two experimental parameters of deposition time and RF power were investigated on the physical properties of the CdTe films. X-ray Diffraction (XRD) analysis showed that the films exhibited polycrystalline nature of CdTe structure with the (111) orientation as the most prominent peak. Optimum condition to grow the CdTe film was obtained and it was found that increasing the deposition time and RF power increases the crystallinity of the films. From the profilometer and XRD data's, the thicknesses and crystal sizes of the CdTe films increased at the higher RF power and the longer deposition time, which results in affecting the band gap as well. From atomic force microscopy (AFM) analysis we found that roughnesses of the films depend on the deposition time and is independent of the RF power.

  14. Properties of CdTe layers deposited by a novel method -Pulsed Plasma Deposition

    OpenAIRE

    Ancora, C.; Nozar, P.; Mittica, G.; Prescimone, F.; A. Neri; Contaldi, S.; Milita, S.; Albonetti, C.; Corticelli, F.; Brillante, A.; Bilotti, I.; Tedeschi, G.; Taliani, C.

    2011-01-01

    CdTe and CdS are emerging as the most promising materials for thin film photovoltaics in the quest of the achievement of grid parity. The major challenge for the advancement of grid parity is the achievement of high quality at the same time as low fabrication cost. The present paper reports the results of the new deposition technique, Pulsed Plasma Deposition (PPD), for the growth of the CdTe layers on CdS/ZnO/quartz and quartz substrates. The PPD method allows to deposit at low temperature. ...

  15. Quantized Nanocrystalline CdTe Thin Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Nanocrystalline CdTe thin films were prepared by asymmetric rectangular pulse electrodeposition in organic solution at 110°C. STM image shows a porous network morphology constructed by interconnected spherical CdTe crystallites with a mean diameter of 4.2 nm. A pronounced size quantization was indicated in the action and absorption spectra. Potentials dependence dual conductive behavior was revealed in the photocurrent-potential (I-V) curves.

  16. Growth of CdTe: Al films; Crecimiento de peliculas de CdTe: Al

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez A, M.; Zapata T, M. [CICATA-IPN, 89600 Altamira, Tamaulipas (Mexico); Melendez L, M. [CINVESTAV-IPN, A.P. 14-740, 07000 Mexico D.F. (Mexico); Pena, J.L. [CINVESTAV-IPN, A.P. 73 Cordemex, 97310 Merida, Yucatan (Mexico)

    2006-07-01

    CdTe: AI films were grown by the close space vapor transport technique combined with free evaporation (CSVT-FE). The Aluminum (Al) evaporation was made by two kinds of sources: one made of graphite and the other of tantalum. The films were deposited on glass substrates. The Al source temperature was varied maintaining the CdTe source temperature fixed as well as the substrate temperature. The films were characterized by x-ray energy dispersive analysis (EDAX), x-ray diffraction and optical transmission. The results showed for the films grown with the graphite source for Al evaporation, the Al did not incorporate in the CdTe matrix, at least to the level of EDAX sensitivity; they maintained the same crystal structure and band gap. For the samples grown with the tantalum source, we were able to incorporate the Al. The x-ray diffraction patterns show that the films have a crystal structure that depends on Al concentration. They were cubic up to 2.16 at. % Al concentration; for 19.65 at. % we found a mixed phase; for Al concentration higher than 21 at. % the films were amorphous. For samples with cubic structure it was found that the lattice parameter decreases and the band gap increases with Al concentration. (Author)

  17. Thin-film CdTe cells: Reducing the CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Plotnikov, V.; Liu, X.; Paudel, N.; Kwon, D.; Wieland, K.A.; Compaan, A.D., E-mail: alvin.compaan@utoledo.edu

    2011-08-31

    Polycrystalline thin-film CdTe is currently the dominant thin-film technology in world-wide PV manufacturing. With finite Te resources world-wide, it is appropriate to consider the limits to reducing the thickness of the CdTe layer in these devices. In our laboratory we have emphasized the use of magnetron sputtering for both CdS and CdTe achieving AM1.5 efficiency over 13% on 3 mm soda-lime glass with commercial TCO and 14% on 1 mm aluminosilicate glass. This deposition technique is well suited to good control of very thin layers and yields relatively small grain size which also facilitates high performance with ultra-thin layers. This paper describes our magnetron sputtering studies for fabrication of very thin CdTe cells. Our thinnest cells had CdTe thicknesses of 1 {mu}m, 0.5 {mu}m and 0.3 {mu}m and yielded efficiencies of 12%, 9.7% and 6.8% respectively. With thinner cells Voc, FF and Jsc are reduced. Current-voltage (J-V), temperature dependent J-V (J-V-T) and apparent quantum efficiency (AQE) measurements provide valuable information for understanding and optimizing cell performance. We find that the stability under light soak appears not to depend on CdTe thickness from 2.5 to 0.5 {mu}m. The use of semitransparent back contacts allows the study of bifacial response which is particularly useful in understanding carrier collection in the very thin devices.

  18. Study of the physical properties of Bi doped CdTe thin films deposited by close space vapour transport

    Energy Technology Data Exchange (ETDEWEB)

    Vigil-Galan, O.; Sanchez-Meza, E.; Sastre-Hernandez, J.; Cruz-Gandarilla, F. [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, 07738 Mexico, D. F. (Mexico); Marin, E. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Instituto Politecnico Nacional, 11500 Mexico, D. F. (Mexico)], E-mail: emarin63@yahoo.es; Contreras-Puente, G. [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, 07738 Mexico, D. F. (Mexico); Saucedo, E.; Ruiz, C.M. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Tufino-Velazquez, M. [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, 07738 Mexico, D. F. (Mexico); Calderon, A. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Instituto Politecnico Nacional, 11500 Mexico, D. F. (Mexico)

    2008-04-30

    Bi doped cadmium telluride (CdTe:Bi) thin films were grown on glass-substrates by the close space vapour transport method. CdTe:Bi crystals grown by the vertical Bridgman method, varying the nominal Bi concentration in the range between 1 x 10{sup 17} and 8 x 10{sup 18} cm{sup -3}, were used in powder form for CdTe:Bi thin film deposition. Dark conductivity and photoconductivity measurements in the 90-300 K temperature range and determination by photoacoustic spectroscopy of the optical-absorption coefficient of the films in the 1.0 to 2.4 eV spectral region were carried out. The influence of Bi doping levels upon the intergrain barrier height and other associated grain boundary parameters of the polycrystalline CdTe:Bi thin films were determined from electrical, optical and morphological characterization.

  19. Properties of CdTe nanocrystalline thin films grown on different substrates by low temperature sputtering

    Institute of Scientific and Technical Information of China (English)

    Chen Huimin; Guo Fuqiang; Zhang Baohua

    2009-01-01

    CdTe nanocrystalline thin films have been prepared on glass, Si and Al2O3 substrates by radio-frequency magnetron sputtering at liquid nitrogen temperature. The crystal structure and morphology of the films were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). The XRD examinations revealed that CdTe films on glass and Si had a better crystal quality and higher preferential orientation along the (111) plane than the Al2O3. FESEM observations revealed a continuous and dense morphology of CdTe films on glass and Si substrates. Optical properties of nanocrystalline CdTe films deposited on glass substrates for different deposited times were studied.

  20. Post-growth CdCl₂ treatment on CdTe thin films grown on graphene layers using a close-spaced sublimation method.

    Science.gov (United States)

    Jung, Younghun; Yang, Gwangseok; Chun, Seungju; Kim, Donghwan; Kim, Jihyun

    2014-05-05

    We investigated the morphological, structural and optical properties of CdCl₂-treated cadmium telluride (CdTe) thin films deposited on defective graphene using a close-spaced sublimation (CSS) system. Heat treatment in the presence of CdCl₂ caused recrystallization of CSS-grown CdTe over the as-deposited structures. The preferential (111) orientation of as-deposited CdTe films was randomized after post-growth CdCl₂ treatment. New small grains (bumps) on the surface of CdCl₂-treated CdTe films were ascribed to nucleation of the CdTe grains during the CdCl₂ treatment. The properties of as-deposited and CdCl₂-treated CdTe films were characterized by room temperature micro-photoluminescence, micro-Raman spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. Our results are useful to demonstrate a substrate configuration CdTe thin film solar cells.

  1. Investigation on the Effect of the CdCl2 Treatment on CdTe Thin-film Solar Cells of Variable Thickness Fabricated Using Combinatorial Pulsed Laser Deposition

    Science.gov (United States)

    Kadhim, Ali Saber

    Cadmium Chloride (CdCl2) post annealing process has significant impacts on the performance of the CdS/CdTe solar cells since it affects the microstructure, crystallinity and charge carrier doping in CdTe films and also the CdS/CdTe p-n junction formed through S and Te interdiffusion at the junction interface. Therefore, this process has been investigated extensively during the past two decades, and has been optimized for polycrystalline CdS/CdTe thick film solar cells, in which the CdTe thickness is typically in the range of 3-8 microm. Nevertheless, the recent effort to develop cost-performance balanced thin film CdS/CdTe solar cells (with CdTe thickness on the order of 1 microm or less) has encountered difficulties through direct applications of the thick-film CdCl2 post annealing process. These difficulties stem from the large CdTe grain sizes typically in the range of microns in the thick film case. Grain boundaries between such large grains result in through-thickness shorts when the CdTe film thickness is comparable to or smaller than the grain size. Overcoming these difficulties to achieve precise controls of grain morphology, crystallinity and CdS/CdTe interface is important to high-performance CdS/CdTe thin film solar cells and will be the main objective of this thesis. In order to accelerate the study, a combinatorial Pulsed Laser Deposition technique (cPLD) was developed for deposition of CdTe films with different thicknesses on each sample to elucidate important physical properties of Cl diffusion through the selected thickness range at a given CdCl 2 annealing condition. Two sets of samples A and B of CdTe solar cells of multiple thicknesses of 1.5, 1.25, 1.0, and 0.75 microm have been fabricated by using cPLD. Sample A was completed without CdCl2 treatment as a reference, and sample B was treated with CdCl2 in different durations (10, 12, 15, and 17 min) at 360°C in mixed vapor of O2 and Argon (25 sccm:100 sccm). The sample that was treated at 15

  2. Preparation and properties of evaporated CdTe films

    Science.gov (United States)

    Bube, R. H.; Fahrenbruch, A. L.; Chien, K. F.

    1987-07-01

    Previous work on evaporated CdTe films for photovoltaics showed no clear path to successful p-type doping of CdTe during deposition. Post-deposition annealing of the films in various ambients thus was examined as a means of doping. Anneals were done in Te, Cd, P, and As vapors and in vacuum, air and Ar, all of which showed large effects on series resistance and diode parameters. With As, series resistance values of In/p-CdTe/graphite structures decreased markedly. This decrease was due to a decrease in grain boundary and/or back contact barrier height, and thus was due to large increases in mobility; the carrier density was not altered substantially. Although the series-resistance decreases were substantial, the diode characteristics became worse. The decreases were not observed when CdS/CdTe cells were fabricated on Te vapor-annealed films. Preparation of ZnO films by reactive evaporation yielded promising results. Deposition of p-ZnTe films by hot-wall vapor evaporation, using conventional techniques, yielded acceptable specimens.

  3. CdTe deposition by successive ionic layer adsorption and reaction (SILAR) technique onto ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Salazar, Raul; Delamoreanu, Alexandru; Saidi, Bilel; Ivanova, Valentina [CEA, LETI, MINATEC Campus, 17 Rue des Martyrs, 38054, Grenoble (France); Levy-Clement, Claude [CNRS, Institut de Chimie et des Materiaux de Paris-Est, 94320, Thiais (France)

    2014-09-15

    In this study is reported CdTe deposition by Successive Ionic Layer Adsorption and reaction (SILAR) at room temperature onto ZnO nanowires (NWs). The as-deposited CdTe layer exhibits poor crystalline quality and not well defined optical transition which is probably result of its amorphous nature. The implementation of an annealing step and chemical treatment by CdCl{sub 2} to the classical SILAR technique improved significantly the CdTe film quality. The XRD analysis showed that the as treated layers are crystallized in the cubic zinc blende structure. The full coverage of ZnO nanowires and thickness of the CdTe shell, composed of small crystallites, was confirmed by STEM and TEM analysis. The layer thickness could be controlled by the number of SILAR cycles. The sharper optical transitions for the annealed and CdCl{sub 2} treated heterostructures additionally proves the enhancement of the layer crystalline quality. For comparison CdTe was also deposited by close space sublimation (CSS) method onto ZnO nanowires. It is shown that the SILAR deposited CdTe exhibits equal crystalline and optical properties to that prepared by CSS. These results demonstrate that SILAR technique is more suitable for conformal thin film deposition on nanostructures. CdTe extremely thin film deposited by SILAR method onto ZnO nanowire. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. The Role of Dopant Concentration on Conductivity and Mobility of CdTe Thin Films

    Directory of Open Access Journals (Sweden)

    Ala J. Al-Douri

    2011-01-01

    Full Text Available Films of CdTe pure and doped with various atomic percentages of Al and Sb (0.5, 1.5 & 2.5 were prepared, and their electrical properties were investigated. The films were prepared by thermal evaporation on glass substrates at two substrate temperatures (Ts=RT & 423 K. The results showed that the conduction phenomena of all the investigated CdTe thin films on glass substrates are caused by two distinct mechanisms. Room temperature DC conductivity increases by a factor of four for undoped CdTe thin films as Ts increases and by 1-2 orders of magnitude with increasing dopant percentage of Al and Sb. In general, films doped with Sb are more efficient than Al-doped films. The activation energy (Ea2 decreases with increasing Ts and dopant percentage for both Al and Sb. Undoped CdTe films deposited at RT are p-type convert to n-type with increasing Ts and upon doping with Al at more than 0.5%. The carrier concentration decreases as Ts increases while it increases with increasing dopant percentage. Hall mobility decreases more than three times as Al increases whereas it increases about one order of magnitude with increasing Sb percentage in CdTe thin films deposited at 423 K and RT, respectively.

  5. Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Annual report, 1 February 1983-31 January 1984

    Energy Technology Data Exchange (ETDEWEB)

    Bube, R; Fahrenbruch, A; Huber, W; Fortmann, C; Thorpe, T

    1984-09-01

    Variation of CdS/CdTe/graphite thick film solar cell properties was investigated as a function of temperature for CdS film deposition. A maximum open-circuit voltage of 0.67 V was found for a deposition temperature of 160/sup 0/C, corresponding to a CdS film resistivity of 150 ohm-cm. The effect is not due to avoidance of higher temperature annealing of the CdTe film in higher temperature CdS film depositions nor to the diffusion of In from the outermost CdS: In layer. The effect of coating the graphite before CdTe deposition with Au or Cu was also investigated. Although high concentrations of both Au or Cu could be determined after CdTe deposition, CdTe films grown on this coated graphite had lower hole densities than films grown on uncoated graphite. Photovoltaic parameters of thin-film CdS/CdTe/graphite solar cells were investigated as a function of storage time to check the stability of these cells. Initial degradation of parameters (especially fill factor) could be reversed by heat treatment in hydrogen, with subsequent properties being stable. Heat treatment of CdS/CdTe/graphite solar cells in air increases cell resistivity and decreases fill factor; heat treatment in hydrogen produces the reverse effect. The hole density is not affected by these heat treatments, suggesting that effects are associated with grain boundaries in the film.

  6. Synthesis of CdTe thin films on flexible metal foil by electrodeposition

    Science.gov (United States)

    Luo, H.; Ma, L. G.; Xie, W. M.; Wei, Z. L.; Gao, K. G.; Zhang, F. M.; Wu, X. S.

    2016-04-01

    CdTe thin films have been deposited onto the Mo foil from aqueous acidic bath via electrodeposition method with water-soluble Na2TeO3 instead of the usually used TeO2. X-ray diffraction studies indicate that the CdTe thin films are crystallized in zinc-blende symmetry. The effect of tellurite concentration on the morphology of the deposited thin film is investigated. In such case, the Cd:Te molar ratios in the films are both stoichiometric at different tellurite concentrations. In addition, the reduction in tellurite concentration leads to the porous thin film and weakens the crystallinity of thin film. The island growth model is used to interpret the growth mechanism of CdTe. The bandgap of the CdTe thin films is assigned to be 1.49 eV from the UV-Vis spectroscopy measurement, which is considered to serve as a promising candidate for the heterojunction solar cells.

  7. Synthesis of CdTe thin films on flexible metal foil by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, H.; Ma, L.G.; Xie, W.M.; Wei, Z.L.; Gao, K.G.; Zhang, F.M.; Wu, X.S. [Nanjing University, Collaborative Innovation Center of Advanced Microstructures, Lab of Solid State Microstructures, School of Physics, Nanjing (China)

    2016-04-15

    CdTe thin films have been deposited onto the Mo foil from aqueous acidic bath via electrodeposition method with water-soluble Na{sub 2}TeO{sub 3} instead of the usually used TeO{sub 2}. X-ray diffraction studies indicate that the CdTe thin films are crystallized in zinc-blende symmetry. The effect of tellurite concentration on the morphology of the deposited thin film is investigated. In such case, the Cd:Te molar ratios in the films are both stoichiometric at different tellurite concentrations. In addition, the reduction in tellurite concentration leads to the porous thin film and weakens the crystallinity of thin film. The island growth model is used to interpret the growth mechanism of CdTe. The bandgap of the CdTe thin films is assigned to be 1.49 eV from the UV-Vis spectroscopy measurement, which is considered to serve as a promising candidate for the heterojunction solar cells. (orig.)

  8. Effects of Sn-doping on morphology and optical properties of CdTe polycrystalline films

    Institute of Scientific and Technical Information of China (English)

    Li Jin; Yang Linyu; Jian Jikang; Zou Hua; Sun Yanfei

    2009-01-01

    Sn-doped CdTe polycrystalline films were successfully deposited on ITO glass substrates by close space sublimation. The effects of Sn-doping on the microstructure, surface morphology, and optical properties of polycrystalline films were studied using X-ray diffraction, scanning electron microscopy, and ultraviolet-visible spectrophotometry, respectively. The results show that the lower molar ratio of Sn and CdTe conduces to a strongly preferential orientation of (111) in films and a larger grain size, which indicates that the crystallinity of films can be improved by appropriate Sn-doping. As the molar ratio of Sn and CdTe increases, the preferential orientation of (111) in films becomes weaker, the grain size becomes smaller, and the crystal boundary becomes indistinct, which indicates that the crystallization growth of films is incomplete. However, as the Sn content increases, optical absorption becomes stronger in the visible region. In summary, a strongly preferential orientation of (111) in films and a larger grain size can be obtained by appropriate Sn-doping (molar ratio of Sn : CdTe = 0.06 : 1), while the film retains a relatively high optical absorption in the visible region. However, Sn-doping has no obvious influence on the energy gap of CdTe films.

  9. Nucleation of CdTe thin films deposited by close-space sublimation under a nitrogen ambient

    Energy Technology Data Exchange (ETDEWEB)

    Major, J.D. [Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Proskuryakov, Y.Y. [Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Durose, K. [Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom)]. E-mail: ken.durose@durham.ac.uk; Green, S. [School of Engineering, Durham University, South Road, Durham, DH1 3LE (United Kingdom)

    2007-05-31

    The early stages of the close-space sublimation growth of CdTe/ITO (indium tin oxide) at 500deg. C under 26.7 kPa (200 Torr) of N{sub 2} were investigated, the relatively high pressure being used to slow the growth. Film development was monitored over 60 mins by ex-situ AFM (atomic force microscopy), the growth being controlled by a shutter. The films formed by the 'island' or Volmer-Weber growth mechanism. Developments in the areal island growth rate, the island density and spatial distribution type were explained using growth mechanisms. Significant changes in these phenomena at t {>=} 10 mins were attributed to a change in growth mechanism from surface migration limited, to a regime in which island coalescence and direct impingement of vapour species on the islands became important. Since the islands are characterised by distinct crystalline facets, this indicates the growth mechanism to be uninterrupted step-flow like addition of material to each island. Arguments are given to relate the final grain size in the films to the density of nuclei that are stable to re-evaporation after t = 10 mins.

  10. Studies of recrystallization of CdTe thin films after CdCl{sub 2} treatment

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Al-Jassim, M.M.; Abulfotuh, F.A.; Levi, D.H.; Dippo, P.C.; Dhere, R.G.; Kazmerski, L.L. [National Renewable Energy Lab., Golden, CO (United States)

    1997-12-31

    CdTe thin films deposited by physical vapor deposition (PVD) and close-spaced sublimation (CSS) have been treated with CdCl{sub 2} at 350 and 400 C. Atomic force microscopy (AFM) analysis showed that the films started recrystallizing during the 350 C CdCl{sub 2} treatment. These results were confirmed by the presence of two lattice parameters, detected in X-ray diffraction (XRD) analysis. The PVD films treated at 400 C were completely recrystallized and grain growth was observed. The formation of Cd(S{sub 1{minus}x}Te{sub x}) alloy in these films was evidenced by the appearance of extra peaks close to the CdTe peaks in the diffraction patterns. No major changes were observed in the structural properties of CSS CdTe films treated at the same conditions. It was concluded that the effect of the CdCl{sub 2} treatment in the CdTe films is to promote recrystallization and grain growth, but only if enough lattice-strain energy is available (as is the case for PVD films). Time-resolved photoluminescence (TRPL) analysis showed, for PVD and CSS films, an increase in minority-carrier lifetime with the treatment, mainly at 400 C, probably due to elimination of deep levels within the band gap.

  11. A photoluminescence study of film structure in CdTe nanoparticle thin films.

    Science.gov (United States)

    Gardner, H C; Gallardo, D E; Dunn, S; Gaponik, N; Eychmüller, A

    2008-05-01

    The layer-by-layer deposition of thin films of CdTe nanoparticles and three different polyelectrolytes has been investigated. Photoluminescence spectra were used to monitor the energy transfer properties within the films. As the number of bilayers in a thin film was increased a decrease in the energy of the light emitted was observed. The wavelength change is a two-stage process. Deposition of the first one to two bi-layers of a thin film produced a sharp energy change (626 nm to 637 nm with the addition of a single bi-layer) whereas deposition of subsequent bi-layers produced a more gradual energy change (642 nm-646 nm with the addition of 5 bi-layers). A space-filling mechanism is suggested to account for these changes; smaller nanoparticles penetrate the earlier levels of a thin film and increase the inter-particle energy transfer opportunities within the layers.

  12. Electronic structure, structural and optical properties of thermally evaporated CdTe thin films

    OpenAIRE

    S Lalitha; Karazhanov, S. Zh.; Ravindran, P.; Senthilarasu, S.; Sathyamoorthy, R.; Janabergenov, J.

    2006-01-01

    Thin films of CdTe were deposited on glass substrates by thermal evaporation. From the XRD measurements itis found that the films are of zinc-blende-type structure. Transmittance, absorption, extinction, and refractive coefficients are measured. Electronic structure, band parameters and optical spectra of CdTe were calculated from ab initio studies within the LDA and LDA+U approximations. It is shown that LDA underestimates the band gap, energy levels of the Cd-4d states, s-d coupling and ban...

  13. Studies on the grain boundary effect in polycrystalline CdTe films using optical reflectance measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, J. (Dept. of Materials Science, Indian Association for the Cultivation of Science, Calcutta (India)); Pal, R. (Dept. of Materials Science, Indian Association for the Cultivation of Science, Calcutta (India)); Bhattacharyya, S.K. (Central Glass and Ceramic Research Inst., Calcutta (India)); Chaudhuri, S. (Dept. of Materials Science, Indian Association for the Cultivation of Science, Calcutta (India)); Pal, A.K. (Dept. of Materials Science, Indian Association for the Cultivation of Science, Calcutta (India))

    1993-11-15

    The grain boundary effect in polycrystalline CdTe films deposited at various substrate temperatures has been studied critically. The grain boundary potential, the density of trap states at the boundary region and the carrier concentration in the films were obtained by an alternative technique that utilizes the reflectance measurements of the highly resistive films deposited on a nonabsorbing substrate. The barrier height in the CdTe films decreased from 0.34 to 0.2 eV as the grain size increased from 60 to 133 nm, owing to the increase in the deposition temperature from 373 to 523 K. Correspondingly, the density of trap states in the grain boundary region decreased from 1.63x10[sup 13] to 6.15x10[sup 12] cm[sup -2]. (orig.)

  14. Vapor transport deposition of large-area polycrystalline CdTe for radiation image sensor application

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Keedong; Cha, Bokyung; Heo, Duchang; Jeon, Sungchae [Korea Electrotechnology Research Institute, 111 Hanggaul-ro, Ansan-si, Gyeonggi-do 426-170 (Korea, Republic of)

    2014-07-15

    Vapor transport deposition (VTD) process delivers saturated vapor to substrate, resulting in high-throughput and scalable process. In addition, VTD can maintain lower substrate temperature than close-spaced sublimation (CSS). The motivation of this work is to adopt several advantages of VTD for radiation image sensor application. Polycrystalline CdTe films were obtained on 300 mm x 300 mm indium tin oxide (ITO) coated glass. The polycrystalline CdTe film has columnar structure with average grain size of 3 μm ∝ 9 μm, which can be controlled by changing the substrate temperature. In order to analyze electrical and X-ray characteristics, ITO-CdTe-Al sandwich structured device was fabricated. Effective resistivity of the polycrystalline CdTe film was ∝1.4 x 10{sup 9}Ωcm. The device was operated under hole-collection mode. The responsivity and the μτ product estimated to be 6.8 μC/cm{sup 2}R and 5.5 x 10{sup -7} cm{sup 2}/V. The VTD can be a process of choice for monolithic integration of CdTe thick film for radiation image sensor and CMOS/TFT circuitry. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Investigation of induced recrystallization and stress in close-spaced sublimated and radio-frequency magnetron sputtered CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Dhere, R.G.; Al-Jassim, M.M.; Levi, D.H.; Kazmerski, L.L. [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)

    1999-07-01

    We have induced recrystallization of small grain CdTe thin films deposited at low temperatures by close-spaced sublimation (CSS), using a standard CdCl{sub 2} annealing treatment. We also studied the changes in the physical properties of CdTe films deposited by radio-frequency magnetron sputtering after the same post-deposition processing. We demonstrated that the effects of CdCl{sub 2} on the physical properties of CdTe films are similar, and independent of the deposition method. The recrystallization process is linked directly to the grain size and stress in the films. These studies indicated the feasibility of using lower-temperature processes in fabricating efficient CSS CdTe solar cells. We believe that, after the optimization of the parameters of the chemical treatment, these films can attain a quality similar to CSS films grown using current standard conditions. {copyright} {ital 1999 American Vacuum Society.}

  16. Facile method to prepare CdS nanostructure based on the CdTe films

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ligang; Chen, Yuehui; Wei, Zelu; Cai, Hongling; Zhang, Fengming; Wu, Xiaoshan, E-mail: xswu@nju.edu.cn

    2015-09-15

    Graphical abstract: - Highlights: • CdS nanostructure is directly fabricated on CdTe film only by heating treatment under H{sub 2}S/N{sub 2} mixed atmosphere at a relatively low temperature (450 °C) with gold layer as the intermediate. • Nanostructure of CdS layer, varying from nanowires to nanosheets, may be controlled by the thickness of gold film. • The change of morphology adjusts its luminescence properties. - Abstract: Nanostructured cadmium sulfide (CdS) plays critical roles in electronics and optoelectronics. In this paper, we report a method to fabricate CdS nanostructure directly on CdTe film, via a thermal annealing method in H{sub 2}S/N{sub 2} mixed gas flow at a relatively low temperature (450 °C). The microstructure and optical properties of CdS nanostructure are investigated by X-ray diffraction, transmission electron microscopy, Raman, and photoluminescence. The morphology of CdS nanostructure, evolving from nanowires to nanosheets, can be controlled by the thickness of Au film deposited on the CdTe film. And CdS nanostructures are single crystalline with the hexagonal wurtzite structure. Raman spectroscopy under varying the excitation wavelengths confirm that synthesized CdS-CdTe films contain two layers, i.e., CdS nanostructure (top) and CdTe layer (bottom). The change of morphology modifies its luminescence properties. Obviously, through simply thermal annealing in H{sub 2}S/N{sub 2} mixed gas, fabricating CdS nanostructure on CdTe film can open up the new possibility for obtaining high efficient CdTe solar cell.

  17. van der Waals epitaxy of CdTe thin film on graphene

    Science.gov (United States)

    Mohanty, Dibyajyoti; Xie, Weiyu; Wang, Yiping; Lu, Zonghuan; Shi, Jian; Zhang, Shengbai; Wang, Gwo-Ching; Lu, Toh-Ming; Bhat, Ishwara B.

    2016-10-01

    van der Waals epitaxy (vdWE) facilitates the epitaxial growth of materials having a large lattice mismatch with the substrate. Although vdWE of two-dimensional (2D) materials on 2D materials have been extensively studied, the vdWE for three-dimensional (3D) materials on 2D substrates remains a challenge. It is perceived that a 2D substrate passes little information to dictate the 3D growth. In this article, we demonstrated the vdWE growth of the CdTe(111) thin film on a graphene buffered SiO2/Si substrate using metalorganic chemical vapor deposition technique, despite a 46% large lattice mismatch between CdTe and graphene and a symmetry change from cubic to hexagonal. Our CdTe films produce a very narrow X-ray rocking curve, and the X-ray pole figure analysis showed 12 CdTe (111) peaks at a chi angle of 70°. This was attributed to two sets of parallel epitaxy of CdTe on graphene with a 30° relative orientation giving rise to a 12-fold symmetry in the pole figure. First-principles calculations reveal that, despite the relatively small energy differences, the graphene buffer layer does pass epitaxial information to CdTe as the parallel epitaxy, obtained in the experiment, is energetically favored. The work paves a way for the growth of high quality CdTe film on a large area as well as on the amorphous substrates.

  18. Fabrication, Electrical Characterization and Simulation of Thin Film Solar Cells: CdTe and CIGS Materials

    OpenAIRE

    Es'haghi Gorji, Nima

    2014-01-01

    CdTe and Cu(In,Ga)Se2 (CIGS) thin film solar cells are fabricated, electrically characterized and modelled in this thesis. We start from the fabrication of CdTe thin film devices where the R.F. magnetron sputtering system is used to deposit the CdS/CdTe based solar cells. The chlorine post-growth treatment is modified in order to uniformly cover the cell surface and reduce the probability of pinholes and shunting pathways creation which, in turn, reduces the series resistance. The deionized wat...

  19. Effect of CdTe Deposition Conditions by Close Spaced Sublimation on Photovoltaic Properties of CdS/CdTe Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Han, B.W.; Ahn, J.H.; Ahn, B.T. [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1998-06-01

    CdTe films were deposited by close spaced sublimation with various substrate temperatures, cell areas, and thickness of CdTe and ITO layers and their effects on the CdS/CdTe solar cells were investigated. The resistivity of CdTe layers employed in this study was 3 X 10{sup 4} {Omega}.cm. For constant substrate temperature the optimum substrate temperature for CdTe deposition was 600 deg. C. To obtain larger grain size and more compact microstructure, CdTe film was initially deposited at 620 deg. C, and then deposited at 540 deg. C. The CdTe film was annealed at 620 deg. C and 600 deg. C sequentially to maintain the CdTe film quality. The photovoltaic cell efficiency improved by the two-wave process. For constant substrate temperature, the optimum thickness for CdTe was 5-6{mu}m. Above 6{mu}m CdTe thickness, the bulk resistance of CdTe film degraded the cell performance. As the cell area increased the V{sub oc} remained almost constant, while J{sub sc} and FF strongly decreased because of the increase of lateral resistance of the ITO layer. The optimum thickness of the ITO layer in this study was 300-450nm. In this experiment we obtained the efficiency of 9.4% in the 0.5cm{sup 2} cells. The series resistance of the cell should be further reduced to increase the fill factor and improve the efficiency. (author). 9 refs.,10 figs.

  20. Optical Properties of Al- and Sb-Doped CdTe Thin Films

    Directory of Open Access Journals (Sweden)

    A. A. J. Al-Douri

    2010-01-01

    Full Text Available Nondoped and (Al, Sb-doped CdTe thin films with 0.5, 1.5, and 2.5  wt.%, respectively, were deposited by thermal evaporation technique under vacuum onto Corning 7059 glass at substrate temperatures ( of room temperature (RT and 423 K. The optical properties of deposited CdTe films such as band gap, refractive index (n, extinction coefficient (, and dielectric coefficients were investigated as function of Al and Sb wt.% doping, respectively. The results showed that films have direct optical transition. Increasing and the wt.% of both types of dopant, the band gap decrease but the optical is constant as n, and real and imaginary parts of the dielectric coefficient increase.

  1. Large area thin film CdTe and Zn(x)Cd(1-x)Te heterojunction solar cells

    Science.gov (United States)

    Chu, T. L.; Chu, S. S.; Firszt, F.; Naseem, H. A.; Stawski, R.

    Thin film CdTe heterojunction solar cells have been prepared by the deposition of p-type CdTe films on CdS/SnO2:F/glass substrates using chemical vapor deposition (CVD) and close-spaced sublimation (CSS) techniques. The relative merits of the two techniques are discussed, and the characteristics of solar cells prepared by CVD and CSS techniques are compared. In addition, the properties of Zn(x)Cd(1-x)Te have been investigated.

  2. CdTe钝化介质膜的溅射沉积及其X射线光电子能谱研究%The Sputtering Deposition and the X-ray Photoelectron Spectroscopy Study for the CdTe Thin Film

    Institute of Scientific and Technical Information of China (English)

    周咏东; 李言谨; 吴小山; 徐国森; 方家熊; 汤定元

    2001-01-01

    用Ar+束溅射沉积技术实现了CdTe薄膜的低温沉积生长。用X射线光电子能谱(XPS)分析技术对溅射沉积CdTe薄膜以及CdTe体晶中的Cd元素、Te元素化学环境进行了对比实验研究。实验表明:溅射沉积CdTe薄膜具有很好的组份均匀性,未探测到有元素(Cd、Te)沉积存在。%The CdTe film was grown by using the low-temperature ion beam sputtering technique. The Cd and Te elements in the sputtering CdTe film sample were studied and compared with those in the CdTe bulk using X-ray photoelectron spectroscopy (XPS) technique. It is proved that the constituent elements in the sputtering CdTe film are homogeneous. No element deposition (Cd, Te) is detceted.

  3. Electro-Plating and Characterisation of CdTe Thin Films Using CdCl2 as the Cadmium Source

    Directory of Open Access Journals (Sweden)

    Nor A. Abdul-Manaf

    2015-09-01

    Full Text Available Cadmium telluride (CdTe thin films have been successfully prepared from an aqueous electrolyte bath containing cadmium chloride (CdCl2·H2O and tellurium dioxide (TeO2 using an electrodeposition technique. The structural, electrical, morphological and optical properties of these thin films have been characterised using X-ray diffraction (XRD, Raman spectroscopy, optical profilometry, DC current-voltage (I-V measurements, photoelectrochemical (PEC cell measurement, scanning electron microscopy (SEM, atomic force microscopy (AFM and UV-Vis spectrophotometry. It is observed that the best cathodic potential is 698 mV with respect to standard calomel electrode (SCE in a three electrode system. Structural analysis using XRD shows polycrystalline crystal structure in the as-deposited CdTe thin films and the peaks intensity increase after CdCl2 treatment. PEC cell measurements show the possibility of growing p-, i- and n-type CdTe layers by varying the growth potential during electrodeposition. The electrical resistivity of the as-deposited layers are in the order of 104 Ω·cm. SEM and AFM show that the CdCl2 treated samples are more roughness and have larger grain size when compared to CdTe grown by CdSO4 precursor. Results obtained from the optical absorption reveal that the bandgap of as-deposited CdTe (1.48–1.52 eV reduce to (1.45–1.49 eV after CdCl2 treatment. Full characterisation of this material is providing new information on crucial CdCl2 treatment of CdTe thin films due to its built-in CdCl2 treatment during the material growth. The work is progressing to fabricate solar cells with this material and compare with CdTe thin films grown by conventional sulphate precursors.

  4. [Spectral analysis of the effect of annealing on CdTe polycrystalline film].

    Science.gov (United States)

    Wang, Wen-Wu; Zheng, Jia-Gui; Feng, Liang-Huan; Cai, Ya-Ping; Lei, Zhi; Zhang, Jing-Quan; Li, Bing; Li, Wei; Wu, Li-Li

    2010-03-01

    Polycrystalline CdTe thin films were prepared by close-spaced sublimation (CCS) and were annealed in different condition. The thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy(XPS). The content distribution and valence state of all elements after annealing were studied. All results show that the as-deposited CdTe thin films are in a cubic phase and have the preferred orientation in (111) direction. After annealing, the peak intensity of (111), (220), (311) grows and the crystal grains grow up, while the crystal boundary decreases. So the compound probabilities of current carrier decrease, therefore shunt resistance and drain current are improved. From detailed analysis of X-ray photoelectron data, it is proposed that tellurium oxides present and its content reduces with depth increasing and that there are TeCl2O building blocks.

  5. Photo-responsivity characterizations of CdTe films for direct-conversion X-ray detectors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ryun Kyung; Cha, Bo Kyung; Jeon, Sung Chae; Seo, Chang Woo [Korea Electrotechnology Research Institute, Ansan (Korea, Republic of); Yun, Seung Man [Pusan National University, Busan (Korea, Republic of)

    2014-08-15

    We have fabricated and investigated thin, polycrystalline, cadmium-telluride (CdTe) films in order to utilize them for optical switching readout layers in direct-conversion X-ray detectors. The polycrystalline CdTe films are fabricated on ITO glasses by using the physical vapor deposition (PVD) method at a slow deposition rate and a pressure of 10{sup -6} torr. CdTe films with thicknesses of 5 and 20 μm are grown. The electrical and the optical characteristics of the CdTe films are investigated by measuring the dark-current and the photo-current as functions of the applied field under different wavelengths of light. Higher photo-currents are generated at the longer wavelengths of light for the same applied voltage. When a higher electrical field is applied to the 20 μm-thick CdTe film, a higher dark-current, a higher photo-current, a larger number of charges, and a higher quantum efficiency are generated.

  6. Preparation and Properties of CdTe Polycrystalline Films for Solar Cells

    Institute of Scientific and Technical Information of China (English)

    ZHENG Huajing; ZHANG Jingquan; FENG Lianghuan; ZHENG Jiagui; CAI Wei; LI Bing; CAI Yaping

    2006-01-01

    The structure and characteristics of CdTe thin films are closely dependent on the whole deposition process in close-space sublimation (CSS). The physical mechanism of CSS was analyzed and the temperature distribution in CSS system was measured, and the influences of the increasing-temperature process and pressure on the preliminary nucleus creation were studied. The results indicate: the samples deposited at different pressures have a cubical structure of CdTe and the diffraction peaks of CdS and SnO2∶F. As the atmosphere pressure increases, the crystal size of CdTe decreases, the rate of the transparency of the thin film decreases and the absorption side moves towards the short-wave direction. After a 4-minute depositing process with a substrate temperature of 500 ℃ and a source temperature of 620 ℃, the polycrystalline thin films can be made, so the production of high-quality integrated cell with SnO2:F/CdS/CdTe/Au structure is hopeful.

  7. Influence of CuxS back contact on CdTe thin film solar cells

    Institute of Scientific and Technical Information of China (English)

    Lei Zhi; Feng Lianghuan; Zeng Guanggen; Li Wei; Zhang Jingquan; Wu Lili; Wang Wenwu

    2013-01-01

    We present a detailed study on CuxS polycrystalline thin films prepared by chemical bath method and utilized as back contact material for CdTe solar cells.The characteristics of the films deposited on Si-substrate are studied by XRD.The results show that as-deposited CuxS thin film is in an amorphous phase while after annealing,samples are in polycrystalline phases with increasing temperature.The thickness of CuxS thin films has great impact on the performance of CdS/CdTe solar cells.When the thickness of the film is about 75 nm the performance of CdS/CdTe thin film solar cells is found to be the best.The energy conversion efficiency can be higher than 12.19%,the filling factor is higher than 68.82% and the open-circuit voltage is more than 820 mV.

  8. Influence of CuxS back contact on CdTe thin film solar cells

    Science.gov (United States)

    Zhi, Lei; Lianghuan, Feng; Guanggen, Zeng; Wei, Li; Jingquan, Zhang; Lili, Wu; Wenwu, Wang

    2013-01-01

    We present a detailed study on CuxS polycrystalline thin films prepared by chemical bath method and utilized as back contact material for CdTe solar cells. The characteristics of the films deposited on Si-substrate are studied by XRD. The results show that as-deposited CuxS thin film is in an amorphous phase while after annealing, samples are in polycrystalline phases with increasing temperature. The thickness of CuxS thin films has great impact on the performance of CdS/CdTe solar cells. When the thickness of the film is about 75 nm the performance of CdS/CdTe thin film solar cells is found to be the best. The energy conversion efficiency can be higher than 12.19%, the filling factor is higher than 68.82% and the open-circuit voltage is more than 820 mV.

  9. Thin film CdTe solar cells by close spaced sublimation: Recent results from pilot line

    Energy Technology Data Exchange (ETDEWEB)

    Siepchen, B., E-mail: bastian.siepchen@ctf-solar.com [CTF Solar GmbH, Industriestraße 2, 65779 Kelkheim (Germany); Drost, C.; Späth, B.; Krishnakumar, V.; Richter, H.; Harr, M. [CTF Solar GmbH, Industriestraße 2, 65779 Kelkheim (Germany); Bossert, S.; Grimm, M. [Roth and Rau AG, An der Baumschule 6-8, 09337 Hohenstein-Ernstthal (Germany); Häfner, K.; Modes, T.; Zywitzki, O.; Morgner, H. [Fraunhofer Institute for Electron Beam and Plasma Technology FEP, Winterbergstrasse 28, 01277 Dresden (Germany)

    2013-05-01

    CdTe is an attractive material to produce high efficient and low cost thin film solar cells. The semiconducting layers of this kind of solar cell can be deposited by the Close Spaced Sublimation (CSS) process. The advantages of this technique are high deposition rates and an excellent utilization of the raw material, leading to low production costs and competitive module prices. CTF Solar GmbH is offering equipment and process knowhow for the production of CdTe solar modules. For further improvement of the technology, research is done at a pilot line, which covers all relevant process steps for manufacture of CdTe solar cells. Herein, we present the latest results from the process development and our research activities on single functional layers as well as for complete solar cell devices. Efficiencies above 13% have already been obtained with Cu-free back contacts. An additional focus is set on different transparent conducting oxide materials for the front contact and a Sb{sub 2}Te{sub 3} based back contact. - Highlights: ► Laboratory established on industrial level for CdTe solar cell research ► 13.0% cell efficiency with our standard front contact and Cu-free back contact ► Research on ZnO-based transparent conducting oxide and Sb{sub 2}Te{sub 3} back contacts ► High resolution scanning electron microscopy analysis of ion polished cross section.

  10. Thermoelectric power and Hall effect measurements in polycrystalline CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Paez, B.A. [Pontificia Univ. Javeriana, Santafe de Bogota (Colombia). Thin Films Group

    2000-07-01

    Polycrystalline CdTe thin films deposited by close space sublimation (CSS), were characterized through thermoelectric power, {alpha}, Hall coefficient, and resistivity, {rho}, measurements in the range of 90 to 400 K. This was in order to determine the scattering mechanisms which mainly affect the electrical transport properties in CdTe thin films. The results were analyzed based on theoretical calculations of {alpha} against temperature. This model includes scattering processes within the grains and at the grain boundaries. Some of the parameters used in this calculation were determined experimentally: grain size, crystal structure, activation energy and effective mass. It is important to state that the main approximations were justified according to experimental measurements. (orig.)

  11. Physical properties of electron beam evaporated CdTe and CdTe:Cu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Punitha, K. [Department of Physics, Alagappa University, Karaikudi 630004 (India); Sivakumar, R., E-mail: krsivakumar1979@yahoo.com [Directorate of Distance Education, Alagappa University, Karaikudi 630004 (India); Sanjeeviraja, C. [Department of Physics, Alagappa Chettiar College of Engineering and Technology, Karaikudi 630004 (India); Sathe, Vasant; Ganesan, V. [UGC-DAE Consortium for Scientific Research, Indore 452001 (India)

    2014-12-07

    In this paper, we report on physical properties of pure and Cu doped cadmium telluride (CdTe) films deposited onto corning 7059 microscopic glass substrates by electron beam evaporation technique. X-ray diffraction study showed that all the deposited films belong to amorphous nature. The average transmittance of the films is varied between 77% and 90%. The optical energy band gap of pure CdTe film is 1.57 eV and it decreased to 1.47 eV upon 4 wt. % of Cu addition, which may be due to the extension of localized states in the band structure. The refractive index of the films was calculated using Swanepoel method. It was observed that the dispersion data obeyed the single oscillator of the Wemple-Didomenico model, from which the dispersion energy (E{sub d}) parameters, dielectric constants, plasma frequency, and oscillator energy (E{sub o}) of CdTe and CdTe:Cu films were calculated and discussed in detail with the light of possible mechanisms underlying the phenomena. The variation in intensity of photoluminescence band edge emission peak observed at 820 nm with Cu dopant is due to the change in surface state density. The observed trigonal lattice of Te peaks in the micro-Raman spectra confirms the p-type conductive nature of films, which was further corroborated by the Hall effect measurement. The lowest resistivity of 6.61 × 10{sup 4} Ω cm was obtained for the CdTe:Cu (3 wt. %) film.

  12. CdTe polycrystalline films on Ni foil substrates by screen printing and their photoelectric performance

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Huizhen [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Ma, Jinwen [College of New Energy, Bohai University, Jinzhou, Liaoning 121013 (China); Mu, Yannan [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Department of Physics and Chemistry, Heihe University, Heihe 164300 (China); Su, Shi; Lv, Pin; Zhang, Xiaoling; Zhou, Liying; Li, Xue; Liu, Li; Fu, Wuyou [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China); Yang, Haibin, E-mail: yanghb@jlu.edu.cn [National Key Lab of Superhard Materials, Jilin University, Changchun 130012 (China)

    2015-06-15

    Highlights: • The sintered CdTe polycrystalline films by a simple screen printing. • The flexible Ni foil was chose as substrates to reduce the weight of the electrode. • The compact CdTe film was obtained at 550 °C sintering temperature. • The photoelectric activity of the CdTe polycrystalline films was excellent. - Abstract: CdTe polycrystalline films were prepared on flexible Ni foil substrates by sequential screen printing and sintering in a nitrogen atmosphere for the first time. The effect of temperature on the quality of the screen-printed film was investigated in our work. The high-quality CdTe films were obtained after sintering at 550 °C for 2 h. The properties of the sintered CdTe films were characterized by scanning electron microscopy, X-ray diffraction pattern and UV–visible spectroscopy. The high-quality CdTe films have the photocurrent was 2.04 mA/cm{sup 2}, which is higher than that of samples prepared at other temperatures. Furthermore, CdCl{sub 2} treatment reduced the band gap of the CdTe film due to the larger grain size. The photocurrent of photoelectrode based on high crystalline CdTe polycrystalline films after CdCl{sub 2} treatment improved to 2.97 mA/cm{sup 2}, indicating a potential application in photovoltaic devices.

  13. Impact of thermal annealing on optical properties of vacuum evaporated CdTe thin films for solar cells

    Science.gov (United States)

    Chander, Subhash; Purohit, A.; Lal, C.; Nehra, S. P.; Dhaka, M. S.

    2016-05-01

    In this paper, the impact of thermal annealing on optical properties of cadmium telluride (CdTe) thin films is investigated. The films of thickness 650 nm were deposited on thoroughly cleaned glass substrate employing vacuum evaporation followed by thermal annealing in the temperature range 250-450 °C. The as-deposited and annealed films were characterized using UV-Vis spectrophotometer. The optical band gap is found to be decreased from 1.88 eV to 1.48 eV with thermal annealing. The refractive index is found to be in the range 2.73-2.92 and observed to increase with annealing treatment. The experimental results reveal that the thermal annealing plays an important role to enhance the optical properties of CdTe thin films and annealed films may be used as absorber layer in CdTe/CdS solar cells.

  14. Effect of film thickness on microstructure parameters and optical constants of CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shaaban, E.R., E-mail: esam_ramadan2008@yahoo.co [Physics Department, Faculty of Science, Qassim University, Buridah 51452 (Saudi Arabia); Physics Department, Faculty of Science, Al-Azhar University, Assiut, P.O. 71452 (Egypt); Afify, N. [Physics Department, Assiut University, Assiut (Egypt); El-Taher, A. [Physics Department, Faculty of Science, Qassim University, Buridah 51452 (Saudi Arabia); Physics Department, Faculty of Science, Al-Azhar University, Assiut, P.O. 71452 (Egypt)

    2009-08-12

    Different thickness of cadmium telluride (CdTe) thin films was deposited onto glass substrates by the thermal evaporation technique. Their structural characteristics were studied by X-ray diffraction (XRD). The XRD experiments showed that the films are polycrystalline and have a zinc-blende (cubic) structure. The microstructure parameters, crystallite size and microstrain were calculated. It is observed that the crystallite size increases and microstrain decreases with the increase in the film thickness. The fundamental optical parameters like band gap and extinction coefficient are calculated in the strong absorption region of transmittance and reflectance spectrum. The possible optical transition in these films is found to be allowed direct transition with energy gap increase from 1.481 to 1.533 eV with the increase in the film thickness. It was found that the optical band gap increases with the increase in thickness. The refractive indices have been evaluated in transparent region in terms of envelope method, which has been suggested by Swanepoul in the transparent region. The refractive index can be extrapolated by Cauchy dispersion relationship over the whole spectral range, which extended from 400 to 2500 nm. It is observed that the refractive index, n increases on increasing the film thickness up to 671 nm and then the variation of n with higher thickness lie within the experimental errors.

  15. Characterization of Highly Efficient CdTe Thin Film Solar Cells by Low-Temperature Photoluminescence

    Science.gov (United States)

    Okamoto, Tamotsu; Matsuzaki, Yuichi; Amin, Nowshad; Yamada, Akira; Konagai, Makoto

    1998-07-01

    Highly efficient CdTe thin film solar cells prepared by close-spaced sublimation (CSS) method with a glass/ITO/CdS/CdTe/Cu-doped carbon/Ag structure were characterized by low-temperature photoluminescence (PL) measurement. A broad 1.42 eV band probably due to VCd Cl defect complexes appeared as a result of CdCl2 treatment. CdS/CdTe junction PL revealed that a CdSxTe1-x mixed crystal layer was formed at the CdS/CdTe interface region during the deposition of CdTe by CSS and that CdCl2 treatment promoted the formation of the mixed crystal layer. Furthermore, in the PL spectra of the heat-treated CdTe after screen printing of the Cu-doped carbon electrode, a neutral-acceptor bound exciton (ACu0, X) line at 1.590 eV was observed, suggesting that Cu atoms were incorporated into CdTe as effective acceptors after the heat treatment.

  16. Impact of thermal annealing on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

    Science.gov (United States)

    Chander, Subhash; Dhaka, M. S.

    2016-06-01

    A study on impact of post-deposition thermal annealing on the physical properties of CdTe thin films is undertaken in this paper. The thin films of thickness 500 nm were grown on ITO and glass substrates employing thermal vacuum evaporation followed by post-deposition thermal annealing in air atmosphere within low temperature range 150-350 °C. These films were subjected to the XRD, UV-Vis NIR spectrophotometer, source meter, SEM coupled with EDS and AFM for structural, optical, electrical and surface topographical analysis respectively. The diffraction patterns reveal that the films are having zinc-blende cubic structure with preferred orientation along (111) and polycrystalline in nature. The crystallographic parameters are calculated and discussed in detail. The optical band gap is found in the range 1.48-1.64 eV and observed to decrease with thermal annealing. The current-voltage characteristics show that the CdTe films exhibit linear ohmic behavior. The SEM studies show that the as-grown films are homogeneous, uniform and free from defects. The AFM studies reveal that the surface roughness of films is observed to increase with annealing. The experimental results reveal that the thermal annealing has significant impact on the physical properties of CdTe thin films and may be used as absorber layer to the CdTe/CdS thin films solar cells.

  17. RF magnetron sputtering deposition of CdTe passivation on HgCdTe

    Science.gov (United States)

    Rutkowski, Jaroslaw; Adamiec, Krzysztof; Rogalski, Antoni

    1998-04-01

    In this study, we report the RF magnetron sputtering growth and characterization of CdTe passivant on bulk n-type HgCdTe. Our investigations include the HgCdTe surface preparation and in-situ pretreatment, deposition-induced surface damage, interface charge, CdTe film stoichiometry, and thermal stability. The metal-insulator-semiconductor test structures are processed and their electrical properties are measured by capacitance-voltage characteristics. The heterostructures are also characterized by reflectance measurement. In order to investigate the passivation properties of CdTe/HgCdTe heterostructures, we have modeled the band diagram of abrupt CdTe/HgCdTe heterojunction. The effect of sputtering growth condition parameters is also reported. The sputtering CdTe layers, exhibit excellent dielectric, insulating and mechano- chemical properties, as well as interface properties. The interfaces are characterized by slight accumulation and a small hysteresis. A carefully controlled growth process and surface pretreatment tailored to the specific material are required in order to obtain near flat band conditions on n- type materials. Additional informations on surface limitations are obtained from analyzing the I-V characteristics of photodiodes with metal gates covering the p-n junction surface location.

  18. Review of Photovoltaic Energy Production Using CdTe Thin-Film Modules: Extended Abstract Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gessert, T. A.

    2008-09-01

    CdTe has near-optimum bandgap, excellent deposition traits, and leads other technologies in commercial PV module production volume. Better understanding materials properties will accelerate deployment.

  19. Fabrication of the structures with autocatalytic CdTe nanowires using magnetron sputtering deposition

    Science.gov (United States)

    Soshnikov, I. P.; Semenov, A. A.; Belyavskii, P. Yu.; Shtrom, I. V.; Kotlyar, K. P.; Lysak, V. V.; Kudryashov, D. A.; Pavlov, S. I.; Nashchekin, A. V.; Cirlin, G. E.

    2016-12-01

    We report the possibility of autocatalytic synthesis of highly crystalline perfect CdTe nanowires by magnetron presputtering deposition through the windows in ultrathin layers of SiO2. The photoluminescence spectra of obtained CdTe nanowires exhibit an emission band in the 1.4-1.7 eV region, indicating crystalline perfection of the nanowires.

  20. Swift heavy ion irradiation induced nanograin formation in CdTe thin films

    Science.gov (United States)

    Survase, Smita; Narayan, Himanshu; Sulania, I.; Thakurdesai, Madhavi

    2016-11-01

    Swift Heavy Ion (SHI) irradiation is a unique technique for nanograin formation through grain fragmentation. Contrary to the generally reported SHI irradiation induced grain growth on CdTe thin films, we report fragmentation leading to nanograin formation. Thermally evaporated polycrystalline CdTe thin films were irradiated with 100 MeV 197Au, 107Ag and 58Ni ions beams up to a fluence of 5 × 1012 ions/cm2. Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) were carried out for surface analysis before and after irradiation. SEM micrographs indicate that the larger grains in the as-deposited films were fragmented into smaller grains due to irradiation. The extent of fragmentation was found to increase with increasing electronic energy loss (Se). AFM pictures also supported the irradiation induced fragmentation. Structural characterization was done using X-ray Diffraction (XRD) technique. The ion induced strain and dislocation density were calculated from the XRD data. Both the strain and dislocation density were found to increase with increasing Se . The observed grain fragmentation is explained on the basis of a combined effect of strain induced disintegration of grains after the Coulomb explosion, and an 'incomplete' re-crystallization of the molten thermal spikes. Moreover, the optical band gap Eg (1.5 eV for as-deposited film), determined from UV-vis spectroscopy, increased with Se, and possibly because of ion induced strain and defect annealing.

  1. Electron and hole drift mobility measurements on thin film CdTe solar cells

    Science.gov (United States)

    Long, Qi; Dinca, Steluta A.; Schiff, E. A.; Yu, Ming; Theil, Jeremy

    2014-07-01

    We report electron and hole drift mobilities in thin film polycrystalline CdTe solar cells based on photocarrier time-of-flight measurements. For a deposition process similar to that used for high-efficiency cells, the electron drift mobilities are in the range of 10-1-100 cm2/V s, and holes are in the range of 100-101 cm2/V s. The electron drift mobilities are about a thousand times smaller than those measured in single crystal CdTe with time-of-flight; the hole mobilities are about ten times smaller. Cells were examined before and after a vapor phase treatment with CdCl2; treatment had little effect on the hole drift mobility, but decreased the electron mobility. We are able to exclude bandtail trapping and dispersion as a mechanism for the small drift mobilities in thin film CdTe, but the actual mechanism reducing the mobilities from the single crystal values is not known.

  2. Physical properties of Bi doped CdTe thin films grown by CSVT and their influence on the CdS/CdTe solar cells PV-properties

    Energy Technology Data Exchange (ETDEWEB)

    Vigil-Galan, O. [Escuela Superior de Fisica y Matematicas-I.P.N., Edificio de Fisica Avanzada, av. IPN y Juan de Dios Batiz s/n U.P.A.L.M. 07738 Mexico D.F. (Mexico)]. E-mail: osvaldo@esfm.ipn.mx; Sanchez-Meza, E. [Escuela Superior de Fisica y Matematicas-I.P.N., Edificio de Fisica Avanzada, av. IPN y Juan de Dios Batiz s/n U.P.A.L.M. 07738 Mexico D.F. (Mexico); Ruiz, C.M. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Madrid 28049 (Spain); Sastre-Hernandez, J. [Escuela Superior de Fisica y Matematicas-I.P.N., Edificio de Fisica Avanzada, av. IPN y Juan de Dios Batiz s/n U.P.A.L.M. 07738 Mexico D.F. (Mexico); Morales-Acevedo, A. [Escuela Superior de Fisica y Matematicas-I.P.N., Edificio de Fisica Avanzada, av. IPN y Juan de Dios Batiz s/n U.P.A.L.M. 07738 Mexico D.F. (Mexico); CINVESTAV-IPN, Electrical Engineering Department, Av. IPN No2508, C. P. 07360, Mexico, D. F. (Mexico); Cruz-Gandarilla, F. [Escuela Superior de Fisica y Matematicas-I.P.N., Edificio de Fisica Avanzada, av. IPN y Juan de Dios Batiz s/n U.P.A.L.M. 07738 Mexico D.F. (Mexico); Aguilar-Hernandez, J. [Escuela Superior de Fisica y Matematicas-I.P.N., Edificio de Fisica Avanzada, av. IPN y Juan de Dios Batiz s/n U.P.A.L.M. 07738 Mexico D.F. (Mexico); Saucedo, E. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Madrid 28049 (Spain); Contreras-Puente, G. [Escuela Superior de Fisica y Matematicas-I.P.N., Edificio de Fisica Avanzada, av. IPN y Juan de Dios Batiz s/n U.P.A.L.M. 07738 Mexico D.F. (Mexico); Bermudez, V. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Madrid 28049 (Spain)

    2007-05-31

    The physical properties of Bi doped CdTe films, grown on glass substrates by the Closed Space Transport Vapour (CSVT) method, from different Bi doped CdTe powders are presented. The CdTe:Bi films were characterized using Photoluminescence, Hall effect, X-Ray diffraction, SEM and Photoconductivity measurements. Moreover, CdS/CdTe:Bi solar cells were made and their characteristics like short circuit current density (J {sub sc}), open circuit voltage (V {sub OC}), fill factor (FF) and efficiency ({eta}) were determined. These devices were fabricated from Bi doped CdTe layers deposited on CdS with the same growth conditions than those used for the single CdTe:Bi layers. A correlation between the CdS/CdTe:Bi solar cell characteristics and the physical properties of the Bi doped CdTe thin films are presented and discussed.

  3. Physical properties of Bi doped CdTe thin films grown by the CSVT method

    Energy Technology Data Exchange (ETDEWEB)

    Vigil-Galan, O.; Sastre-Hernandez, J.; Cruz-Gandarilla, F.; Aguilar-Hernandez, J.; Contreras-Puente, G.; Tufino-Velazquez, M. [Escuela Superior de Fisica y Matematicas, Instituto Politecnico Nacional, 07738 Mexico D. F. (Mexico); Marin, E. [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Instituto Politecnico Nacional, 11500 Mexico, D. F. (Mexico); Saucedo, E.; Ruiz, C.M.; Bermudez, V. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain)

    2006-09-22

    A study of the physical properties of CdTe thin films doped with Bi is presented. CdTe:Bi thin films were deposited by the close space vapor transport (CSVT) technique using powdered CdTe:Bi crystals grown by the vertical Bridgman method. CdTe:Bi crystals were obtained with nominal Bi doping concentrations varying in the 1x10{sup 17}-8x10{sup 18}cm{sup -3} range. The physical properties of CdTe:Bi thin films were studied performing photoluminescence, X-ray, SEM, photoacoustic spectroscopy and resistivity measurements. We observed a decrease of the resistivity values of CdTe:Bi films with the Bi content as low as 6x10{sup 5}{omega}-cm for Bi concentrations of 8x10{sup 18}cm{sup -3}. These are meaningful results for CdTe-based solar cells. (author)

  4. Crystallization from amorphous structure to hexagonal quantum dots induced by an electron beam on CdTe thin films

    Science.gov (United States)

    Becerril, M.; Zelaya-Angel, O.; Medina-Torres, A. C.; Aguilar-Hernández, J. R.; Ramírez-Bon, R.; Espinoza-Beltran, F. J.

    2009-02-01

    Amorphous cadmium-telluride films were prepared by rf sputtering on Corning 7059 glass substrates at room temperature. The deposition time was 10 and 12 h with a thickness of 400 and 480 (±40 nm), respectively. As-prepared films were amorphous according to X-ray diffraction (XRD) patterns, but a win-fit-software analysis of the main XRD broad band suggests a wurtzite structure at short range. Transmission electron microscopy (TEM) at 200 keV produces crystallization of the amorphous CdTe. The TEM-electron beam induces the formation of CdTe quantum dots with the wurtzite hexagonal structure (the metastable structure of CdTe) and with ˜6 nm of average grain size. As effect of a probable distortion of the CdTe crystalline lattice, the unit cell volume (UCV) shrinks to about 30% with respect to the bulk-UCV of CdTe. Besides, the energy band gap increases as expected, according to literature data on quantum confinement.

  5. Structural and electrical properties of polycrystalline CdTe films for direct X-ray imaging detectors

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Bo Kyung, E-mail: goldrain99@kaist.ac.kr [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Repulic of Korea (Korea, Republic of); Yang, Keedong [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Repulic of Korea (Korea, Republic of); Cha, Eun Seok; Yong, Seok-Min [Department of Materials Science and Engineering, KAIST, Daejeon, Repulic of Korea (Korea, Republic of); Heo, Duchang; Kim, Ryun Kyung; Jeon, Seongchae; Seo, Chang-Woo; Kim, Cho Rong [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Repulic of Korea (Korea, Republic of); Ahn, Byung Tae [Department of Materials Science and Engineering, KAIST, Daejeon, Repulic of Korea (Korea, Republic of); Lee, Tae-Bum [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute, Ansan, Repulic of Korea (Korea, Republic of)

    2013-12-11

    We introduce polycrystalline cadmium telluride (CdTe) with high atomic number and density, low effective energy and wide band gap for application in large area diagnostic X-ray digital imaging. In this work, polycrystalline CdTe films were fabricated on ITO/glass substrate by both physical vapor deposition (PVD) with slow deposition rate and pressure of 10{sup −6} Torr and the closed space sublimation (CSS) method with high deposition rate and low vacuum pressure(10{sup −2} Torr). The various polycrystalline CdTe films were grown at different deposition rates and substrate temperatures. Physical properties such as microstructures and the crystal structure of the polycrystalline samples were investigated by SEM and XRD patterns respectively. The PVD method resulted in microstructures with columnar shape and more uniform surface, while the CSS method produced microstructures with many larger grains and less uniform surface. The films were polycrystalline structures with a preferential (111) direction. The electrical and optical properties such as the dark current as a function of applied bias voltage and X-ray sensitivity of the fabricated films were measured and investigated under X-ray exposure.

  6. Structural and electrical properties of polycrystalline CdTe films for direct X-ray imaging detectors

    Science.gov (United States)

    Cha, Bo Kyung; Yang, Keedong; Cha, Eun Seok; Yong, Seok-Min; Heo, Duchang; Kim, Ryun Kyung; Jeon, Seongchae; Seo, Chang-Woo; Kim, Cho Rong; Ahn, Byung Tae; Lee, Tae-Bum

    2013-12-01

    We introduce polycrystalline cadmium telluride (CdTe) with high atomic number and density, low effective energy and wide band gap for application in large area diagnostic X-ray digital imaging. In this work, polycrystalline CdTe films were fabricated on ITO/glass substrate by both physical vapor deposition (PVD) with slow deposition rate and pressure of 10-6 Torr and the closed space sublimation (CSS) method with high deposition rate and low vacuum pressure(10-2 Torr). The various polycrystalline CdTe films were grown at different deposition rates and substrate temperatures. Physical properties such as microstructures and the crystal structure of the polycrystalline samples were investigated by SEM and XRD patterns respectively. The PVD method resulted in microstructures with columnar shape and more uniform surface, while the CSS method produced microstructures with many larger grains and less uniform surface. The films were polycrystalline structures with a preferential (111) direction. The electrical and optical properties such as the dark current as a function of applied bias voltage and X-ray sensitivity of the fabricated films were measured and investigated under X-ray exposure.

  7. Comparative study of electrical properties of Cd and Te-enriched CdTe thin films at cryogenic temperature

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Nazar Abbas, E-mail: nabbasqureshi@yahoo.co [Thin Films Research Laboratory, Department of Physics, COMSATS Institute of Information Technology, Park Road, Islamabad 45320 (Pakistan)

    2010-09-17

    Cd and Te-enriched cadmium telluride (CdTe) polycrystalline thin films were grown on corning glass substrates by Close Spaced Sublimation (CSS) technique. The structural investigations performed by means of X-ray diffraction (XRD) technique, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) showed that the deposited films exhibit a polycrystalline structure with <1 1 1> as preferred orientation. The optical transmittance for Te-enriched CdTe sample was above 0.8 in the range of 1500-2500 nm, which was significantly below 0.8 for Cd-enriched CdTe sample. The electrical properties of these samples were analyzed as a function of the Cd and Te concentration at cryogenic temperature. The electrical resistivity dropped several orders of magnitude. These properties are significantly changed at cryogenic temperature. The comparative study revealed that using this deposition technique, n-type, and p-type Cd and Te-enriched CdTe polycrystalline films can be produced.

  8. SEM, EDS, PL and absorbance study of CdTe thin films grown by CSS method

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Torres, M.E.; Silva-Gonzalez, R.; Gracia-Jimenez, J.M. [Instituto de Fisica, BUAP, Apdo. Postal J-48, San Manuel, 72570 Puebla, Pue. (Mexico); Casarrubias-Segura, G. [CIE- UNAM, 62580 Temixco, Morelos (Mexico)

    2006-09-22

    Oxygen-doped CdTe films were grown on conducting glass substrates by the close spaced sublimation (CSS) method and characterized using SEM, EDS, photoluminescence (PL) and absorbance. A significant change in the polycrystalline morphology is observed when the oxygen proportion is increased in the deposition atmosphere. The EDS analysis showed that all samples are nonstoichiometric with excess Te. The PL spectra show emission bands associated with Te vacancies (V{sub Te}), whose intensities decrease as the oxygen proportion in the CSS chamber is increased. The oxygen impurities occupy Te vacancies and modify the surfaces states, improving the nonradiative process. (author)

  9. Improvement to thin film CdTe solar cells with controlled back surface oxidation

    OpenAIRE

    Rugen-Hankey, S.L.; Clayton, Andrew J; Barrioz, Vincent; Kartopu, Giray; Irvine, Stuart J; McGettrick, J.D.; Hammond, D.

    2015-01-01

    Thin film CdTe solar cells were produced by MOCVD, at atmospheric pressure, under a hydrogen atmosphere (i.e. oxygen-free). Window layer alloying with zinc (forming Cd1−xZnxS) and extrinsic p-type doping with arsenic (giving CdTe:As) have been used to improve photovoltaic solar cell performances, but as-grown MOCVD-CdTe PV cells are still typically characterised by low Voc (~620–690 mV). Post-deposition annealing in air for 30 min at low temperature (170 °C) prior to evaporation of the back c...

  10. Effects of Antimony Doping in Polycrystalline CdTe Thin-Film Solar Cells

    Science.gov (United States)

    Okamoto, Tamotsu; Ikeda, Shigeyuki; Nagatsuka, Satsuki; Hayashi, Ryoji; Yoshino, Kaoru; Kanda, Yohei; Noda, Akira; Hirano, Ryuichi

    2012-10-01

    The effects of antimony (Sb) doping of the CdTe layer in the CdTe solar cells were investigated using Sb-doped CdTe powders as source materials for CdTe deposition by the close-spaced sublimation (CSS) method. Conversion efficiency increased with increasing Sb concentration below 1×1018 cm-3, mainly owing to the improvement of the fill factor. Secondary ion microprobe mass spectrometry (SIMS) depth profile revealed that the Sb impurities at a concentration of approximately 1×1016 cm-3 were incorporated into the CdTe layer when using the Sb-doped CdTe source of 1×1018 cm-3. The observation of surface morphology showed that the grain sizes were improved by Sb addition. Therefore, the improved performance upon Sb addition to CdTe solar cells was probably due to the improvements in crystallinity, such as increased grain size.

  11. Preparation and properties of evaporated CdTe films compared with single crystal CdTe. Progress report No. 4, August 1-October 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Bube, R H

    1981-10-01

    The hot-wall vacuum evaporation system is nearly complete and the first films are expected in early December. CdTe homojunction cells were theoretically modelled and to some extent tested experimentally using the n-type CdTe film on p-type CdTe crystal homojunction cells previously deposited at Linz. Modelling emphasizes the known importance of surface recombination velocity for such homojunction cells. The n-type layer on the experimental cell was thinned by etching from 5 micrometers to 1.5 micrometers, with a corresponding increase in short-circuit current from 0.1 to 1 mA/cm/sup 2/. This behavior is as theoretically expected; to obtain a short-circuit current of 11 mA/cm/sup 2/, as required for a 10% cell, requires a thickness of about 0.2 micrometers for a surface recombination velocity of 10/sup 6/ cm/sec and other realistic cell parameters. By doping experiments on single crystal CdTe, it has been shown that the hole density does decrease when the P dopant density is decreased below a critical value in CdTe:P crystals, thus eliminating the possibility that the major acceptors in the P-doped crystals were not P impurity. Attempts to heavily dope CdTe with As were less successful, but this may be due to the use of elemental As as the dopant in this case rather than a compound of the dopant. Cs was shown to be an effective dopant of CdTe and resistivities as low as 0.3 ohm-cm corresponding to hole densities in the low 10/sup 17/ cm/sup -3/ range were obtained. An apparent correlation between the low-temperature barrier height associated with a grain boundary in CdTe and the angle of mismatch between the two grains has been observed. Improved capacitance of grain boundary measurements should yield defect densities.

  12. Cu-doped CdS and its application in CdTe thin film solar cell

    Directory of Open Access Journals (Sweden)

    Yi Deng

    2016-01-01

    Full Text Available Cu is widely used in the back contact formation of CdTe thin film solar cells. However, Cu is easily to diffuse from the back contact into the CdTe absorber layer and even to the cell junction interface CdS/CdTe. This phenomenon is generally believed to be the main factor affecting the CdTe solar cell stability. In this study Cu was intentionally doped in CdS thin film to study its effect on the microstructural, optical and electrical properties of the CdS material. Upon Cu doping, the VCd− and the surface-state-related photoluminescence emissions were dramatically decreased/quenched. The presence of Cu atom hindered the recrystallization/coalescence of the nano-sized grains in the as-deposited CdS film during the air and the CdCl2 annealing. CdTe thin film solar cell fabricated with Cu-doped CdS window layers demonstrated much decreased fill factor, which was induced by the increased space-charge recombination near the p-n junction and the worsened junction crystalline quality. Temperature dependent current-voltage curve measurement indicated that the doped Cu in the CdS window layer was not stable at both room and higher temperatures.

  13. Cu-doped CdS and its application in CdTe thin film solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Yi [School of Automation, Wuhan University of Technology, Wuhan, Hubei 430070 (China); College of Electronic and Information Engineering, Hankou University, Wuhan, Hubei 430212 (China); Yang, Jun; Yang, Ruilong; Shen, Kai; Wang, Dezhao [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Wang, Deliang, E-mail: eedewang@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Key Laboratory of Materials for Energy Conversion, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2016-01-15

    Cu is widely used in the back contact formation of CdTe thin film solar cells. However, Cu is easily to diffuse from the back contact into the CdTe absorber layer and even to the cell junction interface CdS/CdTe. This phenomenon is generally believed to be the main factor affecting the CdTe solar cell stability. In this study Cu was intentionally doped in CdS thin film to study its effect on the microstructural, optical and electrical properties of the CdS material. Upon Cu doping, the V{sub Cd{sup −}} and the surface-state-related photoluminescence emissions were dramatically decreased/quenched. The presence of Cu atom hindered the recrystallization/coalescence of the nano-sized grains in the as-deposited CdS film during the air and the CdCl{sub 2} annealing. CdTe thin film solar cell fabricated with Cu-doped CdS window layers demonstrated much decreased fill factor, which was induced by the increased space-charge recombination near the p-n junction and the worsened junction crystalline quality. Temperature dependent current-voltage curve measurement indicated that the doped Cu in the CdS window layer was not stable at both room and higher temperatures.

  14. Cu-doped CdS and its application in CdTe thin film solar cell

    Science.gov (United States)

    Deng, Yi; Yang, Jun; Yang, Ruilong; Shen, Kai; Wang, Dezhao; Wang, Deliang

    2016-01-01

    Cu is widely used in the back contact formation of CdTe thin film solar cells. However, Cu is easily to diffuse from the back contact into the CdTe absorber layer and even to the cell junction interface CdS/CdTe. This phenomenon is generally believed to be the main factor affecting the CdTe solar cell stability. In this study Cu was intentionally doped in CdS thin film to study its effect on the microstructural, optical and electrical properties of the CdS material. Upon Cu doping, the VCd- and the surface-state-related photoluminescence emissions were dramatically decreased/quenched. The presence of Cu atom hindered the recrystallization/coalescence of the nano-sized grains in the as-deposited CdS film during the air and the CdCl2 annealing. CdTe thin film solar cell fabricated with Cu-doped CdS window layers demonstrated much decreased fill factor, which was induced by the increased space-charge recombination near the p-n junction and the worsened junction crystalline quality. Temperature dependent current-voltage curve measurement indicated that the doped Cu in the CdS window layer was not stable at both room and higher temperatures.

  15. About the use of photoacoustic spectroscopy for the optical characterization of semiconductor thin films: CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Marin, E.; Calderon, A. [CICATA-IPN, Av. Legaria 694, 11500 Mexico D.F. (Mexico); Vigil G, O.; Sastre, J.; Contreras P, G.; Aguilar H, J. [ESFM-IPN, 07738 Mexico D.F. (Mexico); Saucedo, E.; Ruiz, C.M. [Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, 28049 Madrid (Spain)

    2006-07-01

    CdTe has been used satisfactorily in multiple and diverse technological applications such as detectors of X and gamma rays that operate at room temperature, for digital imagenology of X rays with medical and industrial applications and as active part in CdTe/CdS solar cells. In form of films, CdTe is generally grown with thicknesses ranging between 3 and 15 {mu}m, for which it is difficult to measure, by means of optical techniques, absorption coefficients greater than 10{sup 3} cm{sup -1} because nearly full absorption of light should occur below 800 nm. The exact determination of the optical absorption coefficient in detectors on the basis of CdTe is very important since this parameter determines the absorption length at which 90% of the photons with energies over the forbidden zone of the CdTe will be absorbed by this. In CdS/CdTe polycrystalline solar cells the greater efficiency of conversion have been reported for film thicknesses of 10 mm, however, the optimal value of this parameter depends strongly on the method and the variables of growth. The optical absorption coefficient spectrum can be determined by several methods, often involving several approximations and the knowledge of some minority carrier related electronic parameters that reduce their application in general way. In this work we propose to determine the absorption coefficient in CdTe thin films by photoacoustic spectroscopy (PAS), because this technique allow us to obtain the optical absorption spectra in thicker layers and therefore the study of the influence of the several growth and post-growth processes in the optical properties of this thin films. We measure by PAS the optical-absorption coefficients of CdTe thin films in the spectral region near the fundamental absorption edge ranging from 1.0 to 2.4 eV using an open cell in the transmission configuration. The films were deposited on different substrates by the CSVT-HW (hot wall) technique. In order to study the influence of several

  16. [Spectral analyzing effects of atmosphere states on the structure and characteristics of CdTe polycrystalline thin films made by close-spaced sublimation].

    Science.gov (United States)

    Zheng, Hua-jing; Zheng, Jia-gui; Feng, Liang-huan; Zhang, Jing-quan; Xie, Er-qing

    2005-07-01

    The structure and characteristics of CdTe thin films are dependent on the working atmosphere states in close-spaced sublimation. In the present paper, CdTe polycrystalline thin films were deposited by CSS in mixture atmosphere of argon and oxygen. The physical mechanism of CSS was analyzed, and the temperature distribution in CSS system was measured. The dependence of preliminary nucleus creation on the atmosphere states (involving component and pressure) was studied. Transparencies were measured and optic energy gaps were calculated. The results show that: (1) The CdTe films deposited in different atmospheres are cubic structure. With increasing oxygen concentration, a increases and reaches the maximum at 6% oxygen concentration, then reduces, and increases again after passing the point at 12% oxygen concentration. Among them, the sample depositing at 9% oxygen concentration is the best. The optic energy gaps are 1.50-1.51 eV for all CdTe films. (2) The samples depositing at different pressures at 9% oxygen concentration are all cubical structure of CdTe, and the diffraction peaks of CdS and SnO2:F still appear. With the gas pressure increasing, the crystal size of CdTe minishes, the transparency of the thin film goes down, and the absorption side shifts to the short-wave direction. (3) The polycrystalline thin films with high quality deposit in 4 minutes under the depositing condition that the substrate temperature is 550 degrees C, and source temperature is 620 degrees C at 9% oxygen concentration.

  17. ``CuInSe2 and CdTe thin films for photovoltaic applications''

    Science.gov (United States)

    Attar, G.; Bhethanobolta, D. P.; Dugan, K.; Karthikeyan, S.; Kazi, M.; Killian, J. L.; Muthaiah, A. B.; Nierman, D.; Oman, D. M.; Swaminathan, R.; Zafar, S. A.; Ferekides, C. S.; Morel, D. L.

    1994-06-01

    We are developing processing techniques for CuInSe2 that are manufacturing-friendly due to relaxed controls on deposition conditions. We routinely achieve Jsc's in the range 35-45+ mA/cm2, FF's of 0.55-0.63, and have recently achieved 410 mV in devices without advanced Ga alloying techniques. Our progress and analysis suggests that these processing techniques can achieve state-of-the-art efficiencies. We are also developing an understanding of the complex underlying device mechanisms and their correlation to processing. We propose that a multi-junction classical model which includes space charge recombination can adequately explain device performance and help guide development efforts. The effect of the substrate temperature on the performance of CdTe solar cells prepared by the close spaced sublimation (CSS) process is being investigated. Significant progress has been made and the maximum open-circuit voltage, short-circuit current, and fill factor obtained are 840-860 mV, 22+ mA/cm2, and 69-70% respectively. The extend of interface reaction between the CdTe and CdS layers appears to be dependent on the substrate temperature. Other process parameters such as the total pressure and spacing are of equal importance in obtaining dense CdTe films. Stability studies are also underway in order to determine whether any degradation mechanisms exist and identify their origins.

  18. Molecular beam epitaxy and metalorganic chemical vapor deposition growth of epitaxial CdTe on (100) GaAs/Si and (111) GaAs/Si substrates

    Science.gov (United States)

    Nouhi, A.; Radhakrishnan, G.; Katz, J.; Koliwad, K.

    1988-01-01

    Epitaxial CdTe has been grown on both (100)GaAs/Si and (111)GaAs/Si substrates. A combination of molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD) has been employed for the first time to achieve this growth: the GaAs layers are grown on Si substrates by MBE and the CdTe film is subsequently deposited on GaAs/Si by MOCVD. The grown layers have been characterized by X-ray diffraction, scanning electron microscopy, and photoluminescence.

  19. Effects of CdCl{sub 2} treatment on the recrystallization and electro-optical properties of CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Moutinho, H.R.; Al-Jassim, M.M.; Levi, D.H.; Dippo, P.C.; Kazmerski, L.L. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    1998-05-01

    The effects of CdCl{sub 2} processing on the physical and electro-optical properties of CdTe were evaluated for thin films produced by physical vapor deposition and close-spaced sublimation (CSS). Two substrates (CdS and Indium{endash}tin{endash}oxide) were used with the physical vapor deposition (PVD) films specifically to isolate the effects of the Cd(S{sub x}Te{sub 1{minus}x}) alloy formed during the treatment of films deposited on CdS. The samples were analyzed by x-ray diffraction (XRD), atomic force microscopy (AFM), and photoluminescence. The observed changes in microstructure were caused by recrystallization, which consisted of the nucleation and development of a new CdTe structure and subsequent grain growth. Nevertheless, for these processes to take place, it was necessary that enough lattice-strain energy was available in the films. For this reason, PVD films did recrystallize, while CSS films did not. For the first time, recrystallization was observed directly in AFM images of CdTe films and confirmed by XRD analysis, which indicated the existence of two lattice parameters in PVD samples treated at 350{degree}C. For samples treated at 400{degree}C, the CdCl{sub 2} treatment improved the minority-carrier lifetime of the films by more than one order of magnitude. This improvement was attributed to the elimination of deep defect levels within the band gap of the CdTe films as a result of the treatment. The sulfur diffusion into CdTe films deposited on CdS, during the CdCl{sub 2} treatment at 400{degree}C, strongly affected the defect structure.

  20. Effect of Annealing on the Properties of Antimony Telluride Thin Films and Their Applications in CdTe Solar Cells

    Directory of Open Access Journals (Sweden)

    Zhouling Wang

    2014-01-01

    Full Text Available Antimony telluride alloy thin films were deposited at room temperature by using the vacuum coevaporation method. The films were annealed at different temperatures in N2 ambient, and then the compositional, structural, and electrical properties of antimony telluride thin films were characterized by X-ray fluorescence, X-ray diffraction, differential thermal analysis, and Hall measurements. The results indicate that single phase antimony telluride existed when the annealing temperature was higher than 488 K. All thin films exhibited p-type conductivity with high carrier concentrations. Cell performance was greatly improved when the antimony telluride thin films were used as the back contact layer for CdTe thin film solar cells. The dark current voltage and capacitance voltage measurements were performed to investigate the formation of the back contacts for the cells with or without Sb2Te3 buffer layers. CdTe solar cells with the buffer layers can reduce the series resistance and eliminate the reverse junction between CdTe and metal electrodes.

  1. Nanocrystalline CdTe thin films by electrochemical synthesis

    Directory of Open Access Journals (Sweden)

    Ramesh S. Kapadnis

    2013-03-01

    Full Text Available Cadmium telluride thin films were deposited onto different substrates as copper, Fluorine-doped tin oxide (FTO, Indium tin oxide (ITO, Aluminum and zinc at room temperature via electrochemical route. The morphology of the film shows the nanostructures on the deposited surface of the films and their growth in vertical direction. Different nanostructures developed on different substrates. The X-ray diffraction study reveals that the deposited films are nanocrystalline in nature. UV-Visible absorption spectrum shows the wide range of absorption in the visible region. Energy-dispersive spectroscopy confirms the formation of cadmium telluride.

  2. Characterization of Sputtered CdTe Thin Films with Electron Backscatter Diffraction and Correlation with Device Performance.

    Science.gov (United States)

    Nowell, Matthew M; Scarpulla, Michael A; Paudel, Naba R; Wieland, Kristopher A; Compaan, Alvin D; Liu, Xiangxin

    2015-08-01

    The performance of polycrystalline CdTe photovoltaic thin films is expected to depend on the grain boundary density and corresponding grain size of the film microstructure. However, the electrical performance of grain boundaries within these films is not well understood, and can be beneficial, harmful, or neutral in terms of film performance. Electron backscatter diffraction has been used to characterize the grain size, grain boundary structure, and crystallographic texture of sputtered CdTe at varying deposition pressures before and after CdCl2 treatment in order to correlate performance with microstructure. Weak fiber textures were observed in the as-deposited films, with (111) textures present at lower deposition pressures and (110) textures observed at higher deposition pressures. The CdCl2-treated samples exhibited significant grain recrystallization with a high fraction of twin boundaries. Good correlation of solar cell efficiency was observed with twin-corrected grain size while poor correlation was found if the twin boundaries were considered as grain boundaries in the grain size determination. This implies that the twin boundaries are neutral with respect to recombination and carrier transport.

  3. Biomimetic thin film deposition

    Science.gov (United States)

    Rieke, P. C.; Campbell, A. A.; Tarasevich, B. J.; Fryxell, G. E.; Bentjen, S. B.

    1991-04-01

    Surfaces derivatized with organic functional groups were used to promote the deposition of thin films of inorganic minerals. These derivatized surfaces were designed to mimic the nucleation proteins that control mineral deposition during formation of bone, shell, and other hard tissues in living organisms. By the use of derivatized substrates control was obtained over the phase of mineral deposited, the orientation of the crystal lattice and the location of deposition. These features are of considerable importance in many technically important thin films, coatings, and composite materials. Methods of derivatizing surfaces are considered and examples of controlled mineral deposition are presented.

  4. 14% sputtered thin-film solar cells based on CdTe

    Science.gov (United States)

    Compaan, A. D.; Gupta, A.; Drayton, J.; Lee, S.-H.; Wang, S.

    2004-02-01

    Polycrystalline II-VI semiconductor materials show great promise for thin-film photovoltaic cells and modules. Large-area deposition of these II-VI semiconductors such as CdTe is possible by a variety of methods but the use of a plasma-based method such as magnetron sputtering can have significant advantages. Here we present recent results in the fabrication of CdS/CdTe cells using rf magnetron sputtering and discuss some of the advantages that appear possible from the use of sputtering methods in this class of materials. Some of these advantages are particularly relevant as the polycrystalline thin-film PV community addresses issues related to the challenges of fabricating high efficiency tandem cells with efficiencies over 25%. Our best results have been obtained with sputtered ZnO:Al to achieve a CdTe solar cell with 14.0% efficiency at one sun for an air-mass-1.5 global spectrum. In addition, we have studied reactive sputtering of ZnTe:N which shows promise for use as a transparent back contact or recombination junction for alloyed II-VI-based top cells in a tandem solar-cell configuration.

  5. Sputtered CdTe thin film solar cells with Cu{sub 2}Te/Au back contact

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yongseob [Department of Photoelectronics Information, Chosun College of Science and Technology, Pilmudaero 309-1, Dong-gu, Gwangju 501-744 (Korea, Republic of); Lee, Suho; Yi, Junsin; Choi, Byung-Duck [School of Electronic and Electrical Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of); Kim, Doyoung [School of Electricity and Electronics, Ulsan College, Daehak-ro 57, Nam-gu, Ulsan 680-749 (Korea, Republic of); Lee, Jaehyeong, E-mail: jaehyeong@skku.edu [School of Electronic and Electrical Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2013-11-01

    In this work, Cu{sub 2}Te/Au back contact for CdTe thin film solar cells were prepared by vacuum evaporation. Influence of annealing temperature on the structure and electrical properties of Cu{sub 2}Te films were investigated by field emission scanning electron microscope, X-ray diffraction, and Hall effect measurement. Also, CdS/CdTe thin film solar cells were fabricated by magnetron sputtering process, which is favorable for large area deposition and mass production, and the photovoltaic characteristics were studied. As the annealing temperature was increased, the crystal structure transformed from Cu{sub 2}Te for as-deposited film to Cu{sub 2−x}Te hexagonal phase, and the grains in the film became bigger. The electrical resistivity was slightly higher by the annealing. The cell efficiency was significantly improved by the heat treatment, and showed a maximum value of 9.14% at 180 °C. From these results, Cu{sub 2}Te/Au contact acts as the proper pseudo-ohmic contact onto CdTe film. However, further increase of annealing temperature caused the deterioration of cell performance. - Highlights: • Annealing effects of the vacuum evaporated Cu{sub 2}Te films were investigated. • The transformation from Cu{sub 2}Te to Cu{sub 2−x}Te hexagonal phase occurred by annealing. • The performance of the solar cell was highly increased by annealing at 180 °C. • Cu{sub 2}Te/Au contact acts as the proper pseudo-ohmic contact onto CdTe film.

  6. Influence of thickness on physical properties of vacuum evaporated polycrystalline CdTe thin films for solar cell applications

    Science.gov (United States)

    Chander, Subhash; Dhaka, M. S.

    2016-02-01

    This paper presents the influence of thickness on physical properties of polycrystalline CdTe thin films. The thin films of thickness 450 nm, 650 nm and 850 nm were deposited employing thermal vacuum evaporation technique on glass and indium tin oxide (ITO) coated glass substrates. The physical properties of these as-grown thin films were investigated employing the X-ray diffraction (XRD), source meter, UV-Vis spectrophotometer, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The structural analysis reveals that the films have zinc-blende cubic structure and polycrystalline in nature with preferred orientation (111). The structural parameters like lattice constant, interplanar spacing, grain size, strain, dislocation density and number of crystallites per unit area are calculated. The average grain size and optical band gap are found in the range 15.16-21.22 nm and 1.44-1.63 eV respectively and observed to decrease with thickness. The current-voltage characteristics show that the electrical conductivity is observed to decrease with thickness. The surface morphology shows that films are free from crystal defects like pin holes and voids as well as homogeneous and uniform. The EDS patterns show the presence of cadmium and tellurium elements in the as grown films. The experimental results reveal that the film thickness plays significant role on the physical properties of as-grown CdTe thin films and higher thickness may be used as absorber layer to solar cells applications.

  7. Optical and structural characterization of oleic acid-stabilized CdTe nanocrystals for solution thin film processing

    OpenAIRE

    Claudio Davet Gutiérrez-Lazos; Mauricio Ortega-López; Manuel A. Pérez-Guzmán; A. Mauricio Espinoza-Rivas; Francisco Solís-Pomar; Rebeca Ortega-Amaya; L. Gerardo Silva-Vidaurri; Castro-Peña, Virginia C; Eduardo Pérez-Tijerina

    2014-01-01

    This work presents results of the optical and structural characterization of oleic acid-stabilized cadmium telluride nanocrystals (CdTe-NC) synthesized by an organometallic route. After being cleaned, the CdTe-NC were dispersed in toluene to obtain an ink-like dispersion, which was drop-cast on glass substrate to deposit a thin film. The CdTe-NC colloidal dispersion as well as the CdTe drop-cast thin films were characterized with regard to the optical and structural properties. TEM analysis i...

  8. On the doping problem of CdTe films: The bismuth case

    Energy Technology Data Exchange (ETDEWEB)

    Vigil-Galan, O. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Brown, M. [Department of Physics and Astronomy, The University of Toledo, 43606 Toledo, OH (United States); Ruiz, C.M. [Depto. Fisica de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Vidal-Borbolla, M.A. [Instituto de Investigacion en Comunicacion Optica, Av. Karakorum 1470, Lomas 4a. Secc., 78210 San Luis Potosi, SLP (Mexico); Ramirez-Bon, R. [CINVESTAV-IPN, U. Queretaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, 76230 Santiago de Queretaro, Qro. (Mexico); Sanchez-Meza, E. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Tufino-Velazquez, M. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico)], E-mail: mtufinovel@yahoo.com.mx; Calixto, M. Estela [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Compaan, A.D. [Department of Physics and Astronomy, The University of Toledo, 43606 Toledo, OH (United States); Contreras-Puente, G. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico)

    2008-08-30

    The controlled increase of hole concentration is an important issue and still an unsolved problem for polycrystalline CdTe-based solar cells. The typical hole concentration of as-grown CdTe thin-films goes up to 10{sup 13} cm{sup -3}, depending on the specific growth technique. The highest electron concentration obtained for CdS, the suitable window partner material of CdTe, is around 10{sup 15} cm{sup -3}. Thus, the PV-performance of a CdS/CdTe device can be optimized if the hole concentration in CdTe is increased. We have faced up this problem by studying the electrical properties of two types of CdTe films: CdTe films grown by Close Space Vapor Transport using a CdTe:Bi powder as the starting material and CdTe sputtered films doped by implantation with different Bi-doses. Temperature-dependent resistivity and Hall effect measurements and a discussion on the efficiency of both doping processes are presented.

  9. PENINGKATAN KUALITAS FILM TIPIS CdTe SEBAGAI ABSORBER SEL SURYA DENGAN MENGGUNAKAN DOPING TEMBAGA (Cu

    Directory of Open Access Journals (Sweden)

    P. Marwoto

    2012-12-01

    Full Text Available Film tipis CdTe dengan doping tembaga (Cu berkonsenterasi 2% telah berhasil ditumbuhkan di atas substrat Indium Tin Oxide (ITO dengan metode dc magnetron sputtering. Penelitian ini dilakukan untuk mengetahui pengaruh doping Cu(2% terhadap struktur morfologi, struktur kristal, fotoluminisensi dan resistivitas listrik film CdTe. Citra morfologi Scanning Electron Microscopy (SEM dan hasil analisis struktur dengan X-Ray Diffraction (XRD menunjukkan bahwa film CdTe:Cu(2% mempunyai citra permukaan dan struktur kristal yang lebih sempurna dibandingkan film CdTe tanpa doping. Hasil analisis spektrometer fotoluminisensi menunjukkan bahwa film CdTe dan CdTe(2% mempunyai puncak fotoluminisensi pada tiga panjang gelombang yang identik yaitu 685 nm (1,81 eV, 725 nm (1,71 eV dan 740 nm (1,67 eV. Film CdTe dengan doping Cu(2% memiliki intensitas puncak fotoluminisensi yang lebih tajam pada pita energi 1,81 eV dibandingkan dengan film CdTe tanpa doping. Pengukuran arus dan tegangan (I-V menunjukkan bahwa pemberian doping Cu(2% dapat menurunkan resistivitas film dari 8,40x109 Ωcm menjadi 6,92x105 Ωcm. Sebagai absorber sel surya, kualitas film tipis CdTe telah berhasil ditingkatkan dengan pemberian doping Cu(2%.CdTe:Cu(2% thin film has been successfully grown on Indium Tin Oxide (ITO substrates by using dc magnetron sputtering. This study was carried out in order to investigate the effect of Cu(2% doping on the morphologycal structure, crystal structure, photoluminesence, and resistivity of CdTe thin film. Scanning Electron Microscopy (SEM  images and X-Ray Diffraction (XRD results showed that CdTe:Cu(2% thin film has morphologycal and crystal structures more perfect than undoped CdTe film. Photoluminesence spectroscopy results showed that CdTe and CdTe:Cu(2% thin films have luminesence peak at three identical wevelength regions i.e. 685 nm (1.81 eV, 725 nm (1.71 eV and 740 nm (1.67 eV however CdTe:Cu(2% film shows sharper photoluminescence peak at band

  10. Preparation and multicolored fluorescent properties of CdTe quantum dots/polymethylmethacrylate composite films

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yanni; Liu, Jianjun, E-mail: jjliu717@aliyun.com; Yu, Yingchun; Zuo, Shengli

    2015-10-25

    A new simple route was presented for the preparation of stable fluorescent CdTe/polymethylmethacrylate (CdTe/PMMA) composite films by using hydrophilic thioglycolic acid capped CdTe quantum dots (TGA-CdTe QDs) and polymethylmethacrylate (PMMA) as raw materials. The TGA-CdTe QDs were firstly exchanged with n-dodecanethiol (DDT) to become hydrophobic DDT-CdTe QDs via a ligand exchange strategy, and then incorporated into PMMA matrix to obtain fluorescent CdTe/PMMA composite films. The structure and optical properties of DDT-CdTe QDs and CdTe/PMMA composite films were investigated by XRD, IR, UV and PL techniques. The results indicated that the obtained DDT-CdTe QDs well preserved the intrinsic structure and the maximum emission wavelength of the initial water-soluble QDs and the resulting 6.10 wt% CdTe/PMMA composite film exhibited significantly enhanced PL intensity. Furthermore, the multicolored composite films with green, yellow-green, yellow and orange light emissions were well tuned by incorporating the CdTe QDs of various maximum emission wavelengths. The TEM image demonstrated that the CdTe QDs were well-dispersed in the PMMA matrix without aggregation. Superior photostability of QDs in the composite film was confirmed by fluorescence lifetime measurement. Thermo-gravimetric analysis of CdTe/PMMA composite films showed no obvious enhancement of thermal stability compared with pure PMMA. - Highlights: • Ligand-exchange strategy was used to render CdTe QDs oil-soluble. • CdTe QDs were incorporated into PMMA matrix to fabricate fluorescent films. • The resulting 6.10 wt% CdTe/PMMA film exhibited significantly enhanced PL intensity. • Fluorescent colors of films were tuned by varying the λ{sub em} of incorporated CdTe QDs.

  11. Degradation processes occur on the CdTe thin films solar elements

    CERN Document Server

    Mirsagatov, S A; Makhmudov, M; Muzapharova, S A

    1999-01-01

    It is shown the Cu in CdTe polycristalline films is diffusing on the complex mechanism. By bringing of W atoms in thin CdTe layers it is possible to operate diffusion's speed of Cu atoms. Initiation of the (Cu sup + W sub C sub d sup -) complexes under the conditions N(W sub C sub d sup -)>=N(Cu sub i sup +) hardly reduce the diffusion velocity of Cu atoms.

  12. Atomic-resolution characterization of the effects of CdCl{sub 2} treatment on poly-crystalline CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Paulauskas, T., E-mail: tpaula2@uic.edu; Buurma, C.; Colegrove, E.; Guo, Z.; Sivananthan, S.; Klie, R. F. [Department of Physics, University of Illinois at Chicago, 845 W. Taylor St. M/C 273, Chicago, Illinois 60607-7059 (United States); Chan, M. K. Y. [Center for Nanoscale Materials, Argonne National Laboratory, 9700 S. Cass Ave., Building 440, Argonne, Illinois 60439 (United States)

    2014-08-18

    Poly-crystalline CdTe thin films on glass are used in commercial solar-cell superstrate devices. It is well known that post-deposition annealing of the CdTe thin films in a CdCl{sub 2} environment significantly increases the device performance, but a fundamental understanding of the effects of such annealing has not been achieved. In this Letter, we report a change in the stoichiometry across twin boundaries in CdTe and propose that native point defects alone cannot account for this variation. Upon annealing in CdCl{sub 2}, we find that the stoichiometry is restored. Our experimental measurements using atomic-resolution high-angle annular dark field imaging, electron energy-loss spectroscopy, and energy dispersive X-ray spectroscopy in a scanning transmission electron microscope are supported by first-principles density functional theory calculations.

  13. A pilot investigation on laser annealing for thin-film solar cells: Crystallinity and optical properties of laser-annealed CdTe thin films by using an 808-nm diode laser

    Science.gov (United States)

    Kim, Nam-Hoon; Park, Chan Il; Park, Jinseong

    2013-02-01

    Compared to conventional furnace and rapid thermal annealing, laser annealing for heterojunctioned thin-film solar cells has several advantages including excellent annealing selectivity to the under-layers with a localized high temperature for a short process time. A continuous wave 808-nm diode laser was used for the laser annealing process of CdTe thin films for various output powers. The grains in the laser-annealed CdTe thin films grew along the C (111), H (110), and C (311) planes. Laser annealing resulted in an increase in grain size and a decrease in surface roughness. The optical band gap energy of the CdTe thin films was affected directly by the grain size, showing 1.460 eV and 1.415 eV for the as-deposited and laser-annealed CdTe thin films, respectively. The absorbance of the CdTe thin films with better crystallinity showed an improved value of 99.5-99.9% in the visible spectral region after laser annealing at an output power of 0.91 W.

  14. Biomimetic thin film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L.; Tarasevich, B.J.; Fryxell, G.E.

    1995-09-01

    Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.

  15. Characterization of Smooth CdTe(111) Films by the Conventional Close-Spaced Sublimation Technique

    Science.gov (United States)

    Escobedo, A.; Quinones, S.; Adame, M.; McClure, J.; Zubia, D.; Brill, G.

    2010-04-01

    Thin epitaxial CdTe films were grown on CdTe(111)B substrates by the close-spaced sublimation (CSS) technique and were characterized over a range of experimental parameters. The source temperature was varied between 480°C and 540°C, maintaining an average constant source-substrate temperature difference Δ T of ˜130°C. Helium was used as a carrier gas at pressures between 2 Torr and 10 Torr. Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to analyze the film morphology and structure. Growth rates ranging from 1 μm/h to 4 μm/h were observed, based on profilometer thickness measurements. The addition of a pre-growth heat treatment step and post-growth annealing treatment resulted in smooth CdTe(111) films. An evolution in growth morphology was demonstrated with SEM images and film quality was confirmed with XRD.

  16. The Role of Dopant Concentration on Conductivity and Mobility of CdTe Thin Films

    OpenAIRE

    Al-Douri, Ala J.; Al-Shakily, F. Y.; Alnajjar, Abdalla A.; Maysoon F. A. Alias

    2011-01-01

    Films of CdTe pure and doped with various atomic percentages of Al and Sb (0.5, 1.5 & 2.5) were prepared, and their electrical properties were investigated. The films were prepared by thermal evaporation on glass substrates at two substrate temperatures (Ts=RT & 423 K). The results showed that the conduction phenomena of all the investigated CdTe thin films on glass substrates are caused by two distinct mechanisms. Room temperature DC conductivity increases by a factor of four for undoped CdT...

  17. High-Rate Vapor Deposition of Cadmium Telluride Films for Solar Cells

    Science.gov (United States)

    Khan, Nasim Akhter

    1992-01-01

    High rate vapor deposition is presently used for large scale low cost deposition of thin films for packaging and other applications. The feasibility of using this technology for low cost deposition of solar cells was explored. After an exhaustive literature survey, the cadmium telluride (CdTe) solar cell was found to be most suitable candidate for high rate vapor deposition. The high rate vapor deposition was investigated by sublimation with a short distance between sublimation source and the substrate (Close-Spaced Sublimation, CSS). Cadmium telluride (CdTe) solar cells were fabricated by depositing CdTe films at different rates on cadmium sulphide (CdS) films deposited by CSS or by evaporation. The CdTe films deposited at higher deposition rates were observed to have open circuit voltages (V_{ rm oc}) comparable to those deposited at lower rates. The effect of CdS film which acts as window layer for the cells were also investigated on the V_ {rm oc} of the solar cells. The results achieved proved the fact that CdS window layer is necessary to achieve higher V_{ rm oc} from solar cells. The substrate temperature during deposition of films by close space sublimation plays a vital role in the performance of solar cell. The increase in the substrate temperature during deposition of CdTe films increased the V_{rm oc} of solar cells. The solar cells with indium tin oxide (ITO) as top conductor, i.e. ITO/CdS/CdTe configuration were fabricated at rates up to 34 mum/minute and with tin oxide (TO) i.e. TO/CdTe configuration fabricated at rates up to 79 mum/minute have shown similar V_{rm oc} compared to those produced at lower rates. Higher CdTe film deposition rates are possible with larger capacity experimental setup. The method of contacting CdTe, used in this study, results in higher series resistance. An improved method of contacting CdTe needs to be developed.

  18. Red shift for CdTe nanoparticle thin films and suspensions during heating.

    Science.gov (United States)

    Dunn, S; Gardner, H C; Bertoni, C; Gallardo, D E; Gaponik, N; Eychmüller, A

    2008-05-01

    The work that we have conducted shows that temperature affects the wavelength of light emitted from CdTe nanoparticle clusters that are in a suspension or deposited into thin films via a layer-by-layer process. Compared with the stock suspension, the films show an initial photoluminescent shift, of circa 6-8 nm to the red, when the particles are deposited. A shift of circa 6-8 nm is also seen when the suspensions are first heated to 85 degrees C from room temperature (20 degrees C) having been stored in a fridge at 5 degrees C. This shift is non-recoverable. With continual cycling from room temperature to 85 degrees C the suspensions show a slight tendency for the emission to move increasingly to the red; whereas the films show no such tendency. In both cases, the range in emission is ca 10 nm from the room temperature state to 80 degrees C. The intensity of the emission from the film drops abruptly (ca 50% reduction) after one cycle of heating; in the suspension there is an initial increase (ca 3-5% increase) in intensity before it decays. We see that the shift towards the red has been attributed to energy transfer or a rearrangement of the packing of the particles in the thin films. After conducting analysis of the films using scanning probe microscopy we have determined that a change in the morphology is responsible for the permanent shift in emission wavelength associated with prolonged heating. The influence of traps has not been ruled out, but the morphological change in the samples is very large and is likely to be the dominating mechanism affecting change for the red shift at room temperature.

  19. Rf sputtering of CdTE and CdS for thin film PV

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A.D.; Tabory, C.N.; Shao, M.; Fischer, A.; Feng, Z.; Bohn, R.G. (Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 (United States))

    1994-06-30

    In late 1992 we demonstrated the first rf sputtered CdS/CdTe photovoltaic cell with efficiency exceeding 10%. In this cell both CdS and CdTe layers were deposited by rf sputtering. In this paper we report preliminary measurements of (1) optical emission spectroscopy of the rf plasma, (2) the width of the phonon Raman line as a function of deposition temperature for CdS, and (3) studies of oxygen doping during pulsed laser deposition of CdTe.

  20. A Comparative Study on the Optical Properties of Multilayer CdSe / CdTe Thin Film with Single Layer CdTe and CdSe Films

    Directory of Open Access Journals (Sweden)

    M. Melvin David Kumar

    2013-07-01

    Full Text Available CdTe and CdSe single layer thin films and CdSe / CdTe multilayer (ML thin film were prepared by using physical vapour deposition method. Optical properties of CdSe / CdTe multilayer thin film shows different behavior due to type II band structure alignment. Energy band gap value of CdSe / CdTe ML thin film is shifted to higher value than that of single layer CdTe film. This is due to decrease in crystallite size to dimension smaller than the Bohr exciton radius of CdTe (14 nm. Crystallite size of the multilayer sample was calculated with the predictions of the effective mass approximation model (i.e., Brus model. It is observed that the photoluminescence peak of CdSe / CdTe ML thin film is red shifted compared to the peaks corresponding to individual CdSe and CdTe thin films. This may be due to the presence of type II quantum dot formation in the CdSe / CdTe heterostructure multilayer thin film.

  1. Structural, optical, photoluminescence, dielectric and electrical studies of vacuum-evaporated CdTe thin films

    Indian Academy of Sciences (India)

    Ziaul Raza Khan; M Zulfequar; Mohd Shahid Khan

    2012-04-01

    Highly-oriented CdTe thin films were fabricated on quartz and glass substrates by thermal evaporation technique in the vacuum of about 2 × 10-5 torr. The CdTe thin films were characterized by X-ray diffraction (XRD), UV–VIS–NIR, photoluminescence spectroscopy and scanning electron microscopy (SEM). X-ray diffraction results showed that the films were polycrystalline with cubic structure and had preferred growth of grains along the (111) crystallographic direction. Scanning electron micrographs showed that the growth of crystallites of comparable size on both the substrates. At the room temperature, photoluminescence spectra of the films on both the substrates showed sharp peaks with a maximum at 805 nm. This band showed significant narrowing suggesting that it originates from the transitions involving grain boundary defects. The refractive index of CdTe thin films was calculated using interference pattern of transmission spectra. The optical band gap of thin films was found to allow direct transition with energy gap of 1.47–1.50 eV. a.c. conductivity of CdTe thin films was found to increase with the increase in frequency whereas dielectric constant was observed to decrease with the increase in frequency.

  2. Study of the defect levels, electrooptics, and interface properties of polycrystalline CdTe and CdS thin films and their junction

    Energy Technology Data Exchange (ETDEWEB)

    Abulfotuh, F.A.; Balcioglu, A.; Wangensteen, T.; Moutinho, H.R.; Hassoon, F.; Kazmerski, L.L. [National Renewable Energy Lab., Golden, CO (United States); Al-Douri, A.; Alnajjar, A. [United Arab Emirates Univ., Al-Ain (United Arab Emirates). Physics Dept.

    1997-12-31

    In this study, the electrical behavior of CdS/CdTe junctions was investigated using deep-level transient spectroscopy (DLTS) and capacitance-voltage (c-v) measurements. The results were then correlated to chemical composition and optical properties (measured by using a wavelength-scanning ellipsometer) of the CdTe film and the dominant defect states were determined by photoluminescence (PL) emission measured before and after post-deposition CdCl{sub 2} treatments. CdTe films used in this study were prepared by electrochemical deposition (ED), close-spaced sublimation (CSS), and physical vapor deposition (PVD). The chemical and heat treatments are shown to decrease Cd-vacancy levels (PL measurements), which determine various parameters crucial to the device performance such as the type and concentration of the dominant defects and deep levels, greatly affect the device performance by controlling open-circuit voltage.

  3. Spectrum-per-Pixel Cathodoluminescence Imaging of CdTe Thin-Film Bevels

    Energy Technology Data Exchange (ETDEWEB)

    Moseley, John; Al-Jassim, Mowafak M.; Burst, James; Guthrey, Harvey L.; Metzger, Wyatt K.

    2016-11-21

    We conduct T=6 K cathodoluminescence (CL) spectrum imaging with a nano-scale electron beam on beveled surfaces of CdTe thin-films at different critical stages of standard CdTe device fabrication. The through-thickness total CL intensity profiles are consistent with a reduction in grain boundary recombination due to the CdCl2 treatment. Color-coded maps of the low-temperature luminescence transition energies reveal that CdTe thin films have remarkably non-uniform opto-electronic properties, which depend strongly on sample processing history. The grain-to-grain S content in the interdiffused CdTe/CdS region is estimated from a sample size of thirty-five grains, and the S content in adjacent grains varies significantly in CdCl2-treated samples. A low-temperature luminescence model is developed to interpret spectral behavior at grain boundaries and grain interiors.

  4. Thermal characterization and determination of recombination parameters in CdTe films on glass substrates by using open photoacoustic cell technique

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-T, M.A. [Depto. de C. Basicas, ESCOM-IPN, Av. Miguel Othon de Mendizabal S/N, Col. Lindavista, CP 07738, Mexico DF (Mexico)]. E-mail: mgonzalezt@ipn.mx; Cruz-Orea, A. [Depto. de Fisica, CINVESTAV-IPN, Av. IPN No.2508, Col. San Pedro Zacatenco, CP. 07360, Mexico DF (Mexico); Albor-A, M.L. de [Depto. de Fisica, ESFM-IPN, Edif. 9, U.P. ' Adolfo Lopez Mateos' , CP 07738, Mexico DF (Mexico); Castillo-A, F. de L [Depto. de Fisica, ESFM-IPN, Edif. 9, U.P. ' Adolfo Lopez Mateos' , CP 07738, Mexico DF (Mexico)

    2005-06-01

    CdTe is a semiconductor with a wide variety of applications and perspectives for electronic industry (high-efficiency photoelectric cells, infrared radiation detectors, etc.). In the present work, we used photoacoustic (PA) technique to study the thermal properties and the surface recombination velocity in CdTe/glass samples. Experimental PA phase signal as a function of modulation frequency in a heat transmission configuration was fitted to the theoretical expression for PA signal, which takes into account the heat sources resulting from the absorption of light in semiconductors and the nonradiative processes involved, which depend on their thermal, optical and electronic transport properties. By this procedure, it was possible to determine the thermal diffusivity and the surface recombination velocity in these samples. The studied samples were thin polycrystalline CdTe film deposited on glass slides. CdTe layers were deposited by a hot-wall closed-spaced vapor transport method, known as gradient recrystallization and growth. The values for the deposition parameters used in this study were the following: 700 deg. C for the source temperature and 450 and 550 deg. C for the substrate temperatures with three different deposition times from 5 to 20 min (then three different film thicknesses were obtained). A clear increment in the surface velocity and surface roughness is observed as the film thickness is increased.

  5. Synthesis and optical characterization of nanocrystalline CdTe thin films

    Science.gov (United States)

    Al-Ghamdi, A. A.; Khan, Shamshad A.; Nagat, A.; Abd El-Sadek, M. S.

    2010-11-01

    From several years the study of binary compounds has been intensified in order to find new materials for solar photocells. The development of thin film solar cells is an active area of research at this time. Much attention has been paid to the development of low cost, high efficiency thin film solar cells. CdTe is one of the suitable candidates for the production of thin film solar cells due to its ideal band gap, high absorption coefficient. The present work deals with thickness dependent study of CdTe thin films. Nanocrystalline CdTe bulk powder was synthesized by wet chemical route at pH≈11.2 using cadmium chloride and potassium telluride as starting materials. The product sample was characterized by transmission electron microscope, X-ray diffraction and scanning electron microscope. The structural characteristics studied by X-ray diffraction showed that the films are polycrystalline in nature. CdTe thin films with thickness 40, 60, 80 and 100 nm were prepared on glass substrates by using thermal evaporation onto glass substrate under a vacuum of 10 -6 Torr. The optical constants (absorption coefficient, optical band gap, refractive index, extinction coefficient, real and imaginary part of dielectric constant) of CdTe thin films was studied as a function of photon energy in the wavelength region 400-2000 nm. Analysis of the optical absorption data shows that the rule of direct transitions predominates. It has been found that the absorption coefficient, refractive index ( n) and extinction coefficient ( k) decreases while the values of optical band gap increase with an increase in thickness from 40 to 100 nm, which can be explained qualitatively by a thickness dependence of the grain size through decrease in grain boundary barrier height with grain size.

  6. High efficiency thin film CdTe and a-Si based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A. D.; Deng, X.; Bohn, R. G.

    2000-01-04

    This report describes work done by the University of Toledo during the first year of this subcontract. During this time, the CdTe group constructed a second dual magnetron sputter deposition facility; optimized reactive sputtering for ZnTe:N films to achieve 10 ohm-cm resistivity and {approximately}9% efficiency cells with a copper-free ZnTe:N/Ni contact; identified Cu-related photoluminescence features and studied their correlation with cell performance including their dependence on temperature and E-fields; studied band-tail absorption in CdS{sub x}Te{sub 1{minus}x} films at 10 K and 300 K; collaborated with the National CdTe PV Team on (1) studies of high-resistivity tin oxide (HRT) layers from ITN Energy Systems, (2) fabrication of cells on the HRT layers with 0, 300, and 800-nm CdS, and (3) preparation of ZnTe:N-based contacts on First Solar materials for stress testing; and collaborated with Brooklyn College for ellipsometry studies of CdS{sub x}Te{sub 1{minus}x} alloy films, and with the University of Buffalo/Brookhaven NSLS for synchrotron X-ray fluorescence studies of interdiffusion in CdS/CdTe bilayers. The a-Si group established a baseline for fabricating a-Si-based solar cells with single, tandem, and triple-junction structures; fabricated a-Si/a-SiGe/a-SiGe triple-junction solar cells with an initial efficiency of 9.7% during the second quarter, and 10.6% during the fourth quarter (after 1166 hours of light-soaking under 1-sun light intensity at 50 C, the 10.6% solar cells stabilized at about 9%); fabricated wide-bandgap a-Si top cells, the highest Voc achieved for the single-junction top cell was 1.02 V, and top cells with high FF (up to 74%) were fabricated routinely; fabricated high-quality narrow-bandgap a-SiGe solar cells with 8.3% efficiency; found that bandgap-graded buffer layers improve the performance (Voc and FF) of the narrow-bandgap a-SiGe bottom cells; and found that a small amount of oxygen partial pressure ({approximately}2 {times} 10

  7. Native Defect Control of CdTe Thin Film Solar Cells by Close-Spaced Sublimation

    Science.gov (United States)

    Okamoto, Tamotsu; Kitamoto, Shinji; Yamada, Akira; Konagai, Makoto

    2001-05-01

    The control of native defects in the CdTe thin film solar cells was investigated using a novel source for close-spaced sublimation (CSS) process which was prepared by vacuum evaporation with elemental Cd and Te (evaporated source). The evaporated sources were prepared on glass substrates at room temperature, and the Cd/Te ratio was controlled by varying the Cd and Te beam equivalent pressures. In the cells using the Te-rich source, the conversion efficiency was less than 0.2% because of the extremely low shunt resistance. On the other hand, a conversion efficiency above 15% was obtained by using the Cd-rich source. Capacitance-voltage (C-V) characteristics revealed that the acceptor concentration in the CdTe layer increased with increasing Cd/Te ratio of the evaporated source. Furthermore, photoluminescence spectra implied that the formation of the Cd vacancies in the CdTe layer was suppressed using the Cd-rich source.

  8. Structural and Optical Properties of Sputtered Cadmium Telluride Thin Films Deposited on Flexible Substrates for Photovoltaic Applications.

    Science.gov (United States)

    Song, Woochang; Lee, Kiwon; Kim, Donguk; Lee, Jaehyeong

    2016-05-01

    Cadmium telluride (CdTe) is a photovoltaic technology based on the use of thin films of CdTe to absorb and convert sunlight into electricity. In this paper, polycrystalline CdTe thin films were deposited using radio frequency magnetron sputtering onto flexible substrates including polyimide and molybdenum foil. The structural and optical properties of the films grown at various sputtering pressures were investigated using X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), and UV/Nis/NIR spectrophotometry. The sputtering pressure was found to have significant effects on the structural properties, including crystallinity, preferential orientation, and microstructure. Deterioration of the optical properties of CdTe thin films were observed at high sputtering pressure.

  9. Optical and structural characterization of oleic acid-stabilized CdTe nanocrystals for solution thin film processing

    Directory of Open Access Journals (Sweden)

    Claudio Davet Gutiérrez-Lazos

    2014-06-01

    Full Text Available This work presents results of the optical and structural characterization of oleic acid-stabilized cadmium telluride nanocrystals (CdTe-NC synthesized by an organometallic route. After being cleaned, the CdTe-NC were dispersed in toluene to obtain an ink-like dispersion, which was drop-cast on glass substrate to deposit a thin film. The CdTe-NC colloidal dispersion as well as the CdTe drop-cast thin films were characterized with regard to the optical and structural properties. TEM analysis indicates that the CdTe-NC have a nearly spherical shape (3.5 nm as mean size. Electron diffraction and XRD diffraction analyses indicated the bulk-CdTe face-centered cubic structure for CdTe-NC. An additional diffraction line corresponding to the octahedral Cd3P2 was also detected as a secondary phase, which probably originates by reacting free cadmium ions with trioctylphosphine (the tellurium reducing agent. The Raman spectrum exhibits two broad bands centered at 141.6 and 162.3 cm−1, which could be associated to the TO and LO modes of cubic CdTe nanocrystals, respectively. Additional peaks located in the 222 to 324 cm−1 range, agree fairly well with the wavenumbers reported for TO modes of octahedral Cd3P2.

  10. Optical and structural characterization of oleic acid-stabilized CdTe nanocrystals for solution thin film processing.

    Science.gov (United States)

    Gutiérrez-Lazos, Claudio Davet; Ortega-López, Mauricio; Pérez-Guzmán, Manuel A; Espinoza-Rivas, A Mauricio; Solís-Pomar, Francisco; Ortega-Amaya, Rebeca; Silva-Vidaurri, L Gerardo; Castro-Peña, Virginia C; Pérez-Tijerina, Eduardo

    2014-01-01

    This work presents results of the optical and structural characterization of oleic acid-stabilized cadmium telluride nanocrystals (CdTe-NC) synthesized by an organometallic route. After being cleaned, the CdTe-NC were dispersed in toluene to obtain an ink-like dispersion, which was drop-cast on glass substrate to deposit a thin film. The CdTe-NC colloidal dispersion as well as the CdTe drop-cast thin films were characterized with regard to the optical and structural properties. TEM analysis indicates that the CdTe-NC have a nearly spherical shape (3.5 nm as mean size). Electron diffraction and XRD diffraction analyses indicated the bulk-CdTe face-centered cubic structure for CdTe-NC. An additional diffraction line corresponding to the octahedral Cd3P2 was also detected as a secondary phase, which probably originates by reacting free cadmium ions with trioctylphosphine (the tellurium reducing agent). The Raman spectrum exhibits two broad bands centered at 141.6 and 162.3 cm(-1), which could be associated to the TO and LO modes of cubic CdTe nanocrystals, respectively. Additional peaks located in the 222 to 324 cm(-1) range, agree fairly well with the wavenumbers reported for TO modes of octahedral Cd3P2.

  11. Cd-Te-In oxide thin films as possible transparent buffer layer in CdTe based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Castro-Rodriguez, R; Camacho, J M; Pena, J L [Applied Physics Department, CINVESTAV-IPN Merida, C.P. 97310, Merida, Yucatan (Mexico); Martel, A; Mendez-Gamboa, J, E-mail: romano@mda.cinvestav.m [Facultad de Ingenieria, Universidad Autonoma de Yucatan. AP 150 Cordemex, 97310 Merida, Yucatan (Mexico)

    2009-05-01

    Cd-Te-In-oxide thin films were grown by Pulsed Laser Deposition (PLD) technique using CdTe powder embedded in a matrix of indium metallic as target. The films were deposited at different oxygen pressures (P{sub o2}) from 15 to 50 mTorr at substrate temperature of 420{sup 0}C. Sheet resistance (R{sub sheet}) and transmission spectrum were measured as a function of P{sub o2}. From measurements of optical transmission, the Photonic Flux Density (PFD) spectrum were obtained and the integral of these PFD for each film were evaluated between energy range of 1.5 eV and 2.4 eV for obtain the amount of photons that can be transferred across the film in this range of solar energy spectrum. These values were evaluated over the R{sub sheet} to be used as a figure of merit. The best choice in our conditions was the films with P{sub o2} =28.5 mTorr, where the figure of merit reaches the maximum value.

  12. 12% efficient CdTe/CdS thin film solar cells deposited by low-temperature close space sublimation

    Science.gov (United States)

    Schaffner, Judith; Motzko, Markus; Tueschen, Alexander; Swirschuk, Andreas; Schimper, Hermann-Josef; Klein, Andreas; Modes, Thomas; Zywitzki, Olaf; Jaegermann, Wolfram

    2011-09-01

    We report 12% efficient CdS/CdTe thin film solar cells prepared by low temperature close space sublimation (CSS). Both semiconductor films, CdS and CdTe, were deposited by high vacuum CSS in superstrate configuration on glass substrates with fluorine doped tin oxide (FTO) front contact. The CdTe deposition was carried out at a substrate temperature (Tsub) of ≤340 ∘C, which is much lower than that used in conventional processes (>500 ∘C). The CdTe films were treated with the usual CdCl2 activation process. Different optimal annealing times and temperatures were found for low-temperature cells (Tsub≤ 340 ∘C) compared to high-temperature cells (Tsub = 520 ∘C). The influence of the activation step on the morphology of high-temperature and low-temperature CdTe is determined by XRD, AFM, SEM top views, and SEM cross-sections. Grain growth, strong recrystallization, and a reduction of planar defects during the activation step are observed, especially for low-temperature CdTe. Further, the influence of CdS deposition parameters on the solar cell performance is investigated by using three different sets of parameters with different deposition rates and substrate temperatures for the CdS preparation. Efficiencies about 10.9% with a copper-free back contact and 12.0% with a copper-containing back contact were achieved using the low temperature CdTe process.

  13. Influence of Kilo-Electron Oxygen Ion Irradiation on Structural, Electrical and Optical Properties of CdTe Thin Films

    Science.gov (United States)

    Honey, Shehla; Thema, F. T.; Bhatti, M. T.; Ishaq, A.; Naseem, Shahzad; Maaza, M.

    2016-09-01

    In this paper, effect of oxygen (O+) ion irradiation on the properties of polycrystalline cubic structure CdTe thin films has been investigated. CdTe thin films were irradiated with O+ ions of energy 80keV at different fluence ranging from 1×1015 to 5×1016 ion/cm2 at room temperature. At 1×1015 ion/cm2 O+ ions fluence, the CdTe structure was maintained while XRD peaks of cubic phase were shifted toward lower angles. At 5×1016 ion/cm2 O+ ions fluence, cubic structure of CdTe thin films was transformed into hexagonal structure. In addition, electrical resistivity and optical bandgap were decreased with increasing O+ ion beam irradiation.

  14. Cathodoluminescence spectrum imaging analysis of CdTe thin-film bevels

    Science.gov (United States)

    Moseley, John; Al-Jassim, Mowafak M.; Guthrey, Harvey L.; Burst, James M.; Duenow, Joel N.; Ahrenkiel, Richard K.; Metzger, Wyatt K.

    2016-09-01

    We conducted T = 6 K cathodoluminescence (CL) spectrum imaging with a nanoscale electron beam on beveled surfaces of CdTe thin films at the critical stages of standard CdTe solar cell fabrication. We find that the through-thickness CL total intensity profiles are consistent with a reduction in grain-boundary recombination due to the CdCl2 treatment. The color-coded CL maps of the near-band-edge transitions indicate significant variations in the defect recombination activity at the micron and sub-micron scales within grains, from grain to grain, throughout the film depth, and between films with different processing histories. We estimated the grain-interior sulfur-alloying fraction in the interdiffused CdTe/CdS region of the CdCl2-treated films from a sample of 35 grains and found that it is not strongly correlated with CL intensity. A kinetic rate-equation model was used to simulate grain-boundary (GB) and grain-interior CL spectra. Simulations indicate that the large reduction in the exciton band intensity and relatively small decrease in the lower-energy band intensity at CdTe GBs or dislocations can be explained by an enhanced electron-hole non-radiative recombination rate at the deep GB or dislocation defects. Simulations also show that higher GB concentrations of donors and/or acceptors can increase the lower-energy band intensity, while slightly decreasing the exciton band intensity.

  15. Cathodoluminescence spectrum imaging analysis of CdTe thin-film bevels

    Energy Technology Data Exchange (ETDEWEB)

    Moseley, John [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, USA; Al-Jassim, Mowafak M. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Guthrey, Harvey L. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Burst, James M. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Duenow, Joel N. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Ahrenkiel, Richard K. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA; Colorado School of Mines, 1500 Illinois Street, Golden, Colorado 80401, USA; Metzger, Wyatt K. [National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA

    2016-09-09

    We conducted T = 6 K cathodoluminescence (CL) spectrum imaging with a nanoscale electron beam on beveled surfaces of CdTe thin films at the critical stages of standard CdTe solar cell fabrication. We find that the through-thickness CL total intensity profiles are consistent with a reduction in grain-boundary recombination due to the CdCl2 treatment. The color-coded CL maps of the near-band-edge transitions indicate significant variations in the defect recombination activity at the micron and sub-micron scales within grains, from grain to grain, throughout the film depth, and between films with different processing histories. We estimated the grain-interior sulfur-alloying fraction in the interdiffused CdTe/CdS region of the CdCl2-treated films from a sample of 35 grains and found that it is not strongly correlated with CL intensity. A kinetic rate-equation model was used to simulate grain-boundary (GB) and grain-interior CL spectra. Simulations indicate that the large reduction in the exciton band intensity and relatively small decrease in the lower-energy band intensity at CdTe GBs or dislocations can be explained by an enhanced electron-hole non-radiative recombination rate at the deep GB or dislocation defects. Simulations also show that higher GB concentrations of donors and/or acceptors can increase the lower-energy band intensity, while slightly decreasing the exciton band intensity.

  16. K-edge EXAFS and XANES studies of Cu in CdTe thin-film solar cells

    Science.gov (United States)

    Liu, Xiangxin; Gupta, Akhlesh; Compaan, Alvin D.; Leyarovska, Nadia; Terry, Jeff

    2002-03-01

    Copper has been identified as a very important dopant element in CdTe thin-film solar cells. Cu is a deep acceptor in CdTe and is commonly used to obtain a heavily doped, low resistance back contact to polycrystalline CdTe. Cu also helps to increase the open circuit voltage of the cell. However, Cu is also a fast diffuser in CdTe, especially along grain boundaries, and can accumulate at the CdS/CdTe junction. It is suspected of leading to cell performance degradation in some cases. The present study is designed to help identify the lattice location of the Cu in CdTe. Cu K-edge, x-ray absorption (XAS) measurements were conducted on Cu in thin films of CdTe. Experiments were performed at the MR-CAT beamline at the Advanced Photon Source. The 3 mm CdTe layers were magnetron sputtered onto fused silica substrates. Some films were diffused with Cu from a 200 Å layer of evaporated Cu. XAS spectra were collected in fluorescence geometry with a 13 elements Ge detector. Quantitative fluorescence spectroscopy measurements were also performed. Details of the Cu environment and possible changes with time will be reported.

  17. Identification of critical stacking faults in thin-film CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Su-Hyun; Walsh, Aron, E-mail: a.walsh@bath.ac.uk [Global E3 Institute, Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Butler, Keith T. [Centre for Sustainable Chemical Technologies and Department of Chemistry, University of Bath, Bath BA2 7AY (United Kingdom); Soon, Aloysius [Global E3 Institute, Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Abbas, Ali; Walls, John M., E-mail: j.m.wall@loughborough.ac.uk [Centre for Renewable Energy Systems Technology, School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2014-08-11

    Cadmium telluride (CdTe) is a p-type semiconductor used in thin-film solar cells. To achieve high light-to-electricity conversion, annealing in the presence of CdCl{sub 2} is essential, but the underlying mechanism is still under debate. Recent evidence suggests that a reduction in the high density of stacking faults in the CdTe grains is a key process that occurs during the chemical treatment. A range of stacking faults, including intrinsic, extrinsic, and twin boundary, are computationally investigated to identify the extended defects that limit performance. The low-energy faults are found to be electrically benign, while a number of higher energy faults, consistent with atomic-resolution micrographs, are predicted to be hole traps with fluctuations in the local electrostatic potential. It is expected that stacking faults will also be important for other thin-film photovoltaic technologies.

  18. Analyses of photoluminescence spectra of CdTe thin films at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad-Bitar, R. [University of Jordan, Amman (Jordan); Moutinho, H.; Abulfotuh, F.; Kazmerski, L. [Solar Energy Research Inst., Golden, CO (United States)

    1995-11-01

    Photoluminescence (PL) spectra of thin films of CdTe grown on glass by evaporation have been obtained at different laser powers and at different temperatures near and to the red end of the band gap. We suggest an analytical method which deconvolutes the PL spectrum into peaks corresponding to the main electronic transitions. Each spectrum was analytically fitted to eight Gaussian peaks. Gaussian peaks have been found to give the best fit to the spectrum. The quality of the fit can be checked by the fact that the positions and the widths of the eight peaks of each PL spectrum should agree with the fit to another spectrum taken at a different excitation power or a different sample temperature. These results may help to identify these peaks and suggest a model for the shallow electrically active states between the conduction and valance bands of CdTe thin films. (Author)

  19. Admittance spectroscopy characterize graphite paste for back contact of CdTe thin film solar cells

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    CdTe thin film solar cells with a doped-graphite paste back contact layer were studied using admittance spectroscopy technology.The positions and the capture cross sections of energy level in the forbidden band were calculated,which are the important parameters to affect solar cell performance.The results showed that there were three defects in the CdTe thin films solar cells with the doped-graphite paste back contact layer,whose positions in the forbidden band were close to 0.34,0.46 and 0.51 eV,respectively above the valence band,and capture cross sections were 2.23×10-16,2.41×10-14,4.38×10-13 cm2,respectively.

  20. In-depth analysis of chloride treatments for thin-film CdTe solar cells

    OpenAIRE

    Major, J.D.; Al Turkestani, M.; Bowen, L; Brossard, M.; Li, C; Lagoudakis, P.; S. J. Pennycook; Phillips, L. J.; Treharne, R. E.; Durose, K.

    2016-01-01

    CdTe thin-film solar cells are now the main industrially established alternative to silicon-based photovoltaics. These cells remain reliant on the so-called chloride activation step in order to achieve high conversion efficiencies. Here, by comparison of effective and ineffective chloride treatments, we show the main role of the chloride process to be the modification of grain boundaries through chlorine accumulation, which leads an increase in the carrier lifetime. It is also demonstrated th...

  1. Anomalous scaling and super-roughness in the growth of CdTe polycrystalline films

    OpenAIRE

    Mata, Angélica S.; Ferreira, Jr,Augusto; Ribeiro, Igor R. B.; Ferreira, Sukarno O.

    2011-01-01

    CdTe films grown on glass substrates covered by fluorine doped tin oxide by Hot Wall Epitaxy (HWE) were studied through the interface dynamical scaling theory. Direct measures of the dynamical exponent revealed an intrinsically anomalous scaling characterized by a global roughness exponent $\\alpha$ distinct from the local one (the Hurst exponent $H$), previously reported [Ferreira \\textit{et al}., Appl. Phys. Lett. \\textbf{88}, 244103 (2006)]. A variety of scaling behaviors was obtained with ...

  2. Thin Film Deposition Techniques (PVD)

    Science.gov (United States)

    Steinbeiss, E.

    The most interesting materials for spin electronic devices are thin films of magnetic transition metals and magnetic perovskites, mainly the doped La-manganites [1] as well as several oxides and metals for passivating and contacting the magnetic films. The most suitable methods for the preparation of such films are the physical vapor deposition methods (PVD). Therefore this report will be restricted to these deposition methods.

  3. The effect of substrate rotation rate on physical properties of cadmium telluride films prepared by a glancing angle deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini Siyanaki, Fatemeh, E-mail: fatemeh.hosseini@gmail.com; Rezagholipour Dizaji, Hamid, E-mail: hrgholipour@semnan.ac.ir; Ehsani, Mohammad Hossein, E-mail: mhe_ehsani@yahoo.com; Khorramabadi, Shiva, E-mail: khorramabadi.sh@gmail.com

    2015-02-27

    Physical properties of cadmium telluride thin films, deposited on glass substrates by modified glancing angle deposition (GLAD) technique with various substrate rates of rotation, were investigated in this study. In contrast to obliquely columnar thin films fabricated by the conventional GLAD technique, in which higher columnar angle is coupled to higher degree of porosity, this study introduces obliquely deposited thin films which have packed columnar structures despite their highly tilted columns. Structural and optical properties and surface morphology of the CdTe thin films deposited by this technique were studied using X-ray diffraction, UV–visible spectroscopy and field emission scanning electron microscopy. - Highlights: • Glancing angle deposition technique was employed to prepare CdTe thin films. • The effect of substrate rate of rotation on optical properties was studied. • Highly tilted and packed columnar structure was fabricated. • A dramatic decline in refractive index in one of the specimens was observed.

  4. Modeling the defect distribution and degradation of CdTe ultrathin films

    Science.gov (United States)

    Gorji, Nima E.

    2014-12-01

    The defect distribution across an ultrathin film CdTe layer of a CdS/CdTe solar cell is modelled by solving the balance equation in steady state. The degradation of the device parameters due to the induced defects during ion implantation is considered where the degradation rate is accelerated if the defect distribution is considerable. The defect concentration is maximum at the surface of the CdTe layer where implantation is applied and it is minimum at the junction with the CdS layer. It shows that ultrathin devices degrade faster if the defect concentration is high at the junction rather than the back region (CdTe/Metal). Since the front and back contacts of the device are close in ultrathin films and the electric field is strong to drive the defects into the junction, the p-doping process might be precisely controlled during ion implantation. The modeling results presented here are in agreement with the few available experimental reports in literature about the degradation and defect configuration of the ultrathin CdTe films.

  5. High-Efficiency CdTe and CIGS Thin-Film Solar Cells: Highlights and Challenges; Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Noufi, R.; Zweibel, K.

    2006-05-01

    Thin-film photovoltaic (PV) modules of CdTe and Cu(In,Ga)Se2 (CIGS) have the potential to reach cost-effective PV-generated electricity. These technologies have transitioned from the laboratory to the market place. Pilot production and first-time manufacturing are ramping up to higher capacity and enjoying a flood of venture-capital funding. CIGS solar cells and modules have achieved 19.5% and 13% efficiencies, respectively. Likewise, CdTe cells and modules have reached 16.5% and 10.2% efficiencies, respectively. Even higher efficiencies from the laboratory and from the manufacturing line are only a matter of time. Manufacturing-line yield continues to improve and is surpassing 85%. Long-term stability has been demonstrated for both technologies; however, some failures in the field have also been observed, emphasizing the critical need for understanding degradation mechanisms and packaging options. The long-term potential of the two technologies require R&D emphasis on science and engineering-based challenges to find solutions to achieve targeted cost-effective module performance, and in-field durability. Some of the challenges are common to both, e.g., in-situ process control and diagnostics, thinner absorber, understanding degradation mechanisms, protection from water vapor, and innovation in high-speed processing and module design. Other topics are specific to the technology, such as lower-cost and fast-deposition processes for CIGS, and improved back contact and voltage for CdTe devices.

  6. Fabrication of solar cells based on polycrystalline CdTe thin films using an economical production. Energie

    Energy Technology Data Exchange (ETDEWEB)

    Tranchart, J.C.; Boucherez, P.

    1983-01-01

    Polycrystalline CdS and CdTe films were produced by serigraphy. High-quality CdS films were obtained, especially with CdCl as melting phase. In the field of CdTe films, further studies are required in order to improve the sintering process, the film porosity characteristics, and the electric resistivity which decides the serial conductivity of the n-CdS/p-CdTe structures. In the field of solar cells, quartz +In/sub 2/O/sub 3/+CdS+CdTe heterostructures with a photoelectric efficiency of 2.5% were obtained. This value is too low, even if the economic advantages of serigraphy are taken into account. Further studies should center on the sintering process for CdTe films.

  7. Study of the Mg incorporation in CdTe for developing wide band gap Cd{sub 1-x}Mg{sub x}Te thin films for possible use as top-cell absorber in a tandem solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Omar S. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Universidad Politecnica del Estado de Guerrero, Comunidad de Puente Campuzano, C.P. 40325 Taxco de Alarcon, Guerrero (Mexico); Millan, Aduljay Remolina [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Huerta, L.; Santana, G. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico. C.P 04510 Mexico D.F. (Mexico); Mathews, N.R.; Ramon-Garcia, M.L.; Morales, Erik R. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico); Mathew, X., E-mail: xm@cie.unam.mx [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, 62580 Temixco, Morelos (Mexico)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Thin films of Cd{sub 1-x}Mg{sub x}Te with high spatial uniformity and band gap in the range of 1.6-1.96 eV were deposited by vacuum co-evaporation of CdTe and Mg. Black-Right-Pointing-Pointer Obtained Cd{sub 1-x}Mg{sub x}Te films have the structural characteristics of the CdTe, evidence of the change in atomic scattering due to incorporation of Mg was observed. Black-Right-Pointing-Pointer XRD and XPS data confirmed the incorporation of Mg in the lattice of CdTe. Black-Right-Pointing-Pointer SEM images revealed the impact of Mg incorporation on the morphology of the films, the changes in grain size and grain morphology are noticeable. - Abstract: Thin films of Cd{sub 1-x}Mg{sub x}Te with band gap in the range of 1.6-1.96 eV were deposited by vacuum co-evaporation of CdTe and Mg on glass substrates heated at 300 Degree-Sign C. Different experimental techniques such as XRD, UV-vis spectroscopy, SEM, and XPS were used to study the effect of Mg incorporation into the lattice of CdTe. The band gap of the films showed a clear tendency to increase as the Mg content in the film is increased. The Cd{sub 1-x}Mg{sub x}Te films maintain all the structural characteristics of the CdTe, however, diminishing of intensity for the XRD patterns is observed due to both change in preferential orientation and change in atomic scattering due to the incorporation of Mg. SEM images showed significant evidences of morphological changes due to the presence of Mg. XRD, UV-vis spectroscopy, and XPS data confirmed the incorporation of Mg in the lattice of CdTe. The significant increase in band gap of CdTe due to incorporation of Mg suggests that the Cd{sub 1-x}Mg{sub x}Te thin film is a candidate material to use as absorber layer in the top-cell of a tandem solar cell.

  8. Growth of ZnO nanowires through thermal oxidation of metallic zinc films on CdTe substrates

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, O., E-mail: oscar@fmc.uva.es [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011, Valladolid (Spain); Hortelano, V.; Jimenez, J. [Optronlab Group, Dpto. Fisica Materia Condensada, Edificio I-D, Universidad de Valladolid, Paseo de Belen 1, 47011, Valladolid (Spain); Plaza, J.L.; Dios, S. de; Olvera, J.; Dieguez, E. [Laboratorio de Crecimiento de Cristales, Departamento de Fisica de Materiales, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Fath, R.; Lozano, J.G.; Ben, T.; Gonzalez, D. [Dpto. Ciencia de los Materiales e Ingenieria Metalurgica y Q.I., Facultad de Ciencias, Apdo. 40, 11510 Puerto Real, Cadiz (Spain); Mass, J. [Dpto. de Fisica, Universidad del Norte, Km.5 Via Puerto Colombia, Barranquilla (Colombia)

    2011-04-28

    Research highlights: > ZnO nanowires grown from thermal Zn oxidation. > TEM reveals high quality thin nanowires several microns long. > New phase formation at long oxidation time. > Good spectroscopic properties measured by Raman, Photo and Cathodoluminsecence spectroscopies. - Abstract: <112-bar 0> wurtzite ZnO nanowires (NWs) have been obtained by oxidizing in air at 500 deg. C thermally evaporated Zn metal films deposited onto CdTe substrates. The presence of Cd atoms from the substrate on the ZnO seeding layer and NWs seems to affect the growth of the NWs. The effects of the oxidation time on the structural and optical properties of the NWs are described in detail. It is shown that the NWs density decreases and their length increases when increasing the oxidation time. Thicker Zn layers result in thinner and longer ZnO NWs. Very long oxidation times also lead to the formation of a new CdO phase which is related to the partial destruction and quality reduction of the NWs. The possible process for ZnO NW formation on CdTe substrates is discussed.

  9. Variable temperature semiconductor film deposition

    Science.gov (United States)

    Li, Xiaonan; Sheldon, Peter

    1998-01-01

    A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  10. Influence of Zn2+ doping on the crystal structure and optical-electrical properties of CdTe thin films

    Science.gov (United States)

    Kavitha, R.; Sakthivel, K.

    2015-10-01

    The present study reports the synthesis of Cd1-xZnxTe (x = 0, 0.025, 0.050, 0.075 and 0.100) nanocrystalline thin film through a simple two step method. In the first step fine nanoparticles of Cd1-xZnxTe was prepared by solvothermal microwave irradiation (SMI) technique and then deposited as thin film using dip-coating technique. X-ray diffraction study showed that films are polycrystalline with cubic phase, which are preferentially oriented along the (1 1 1) direction. No impurity phase was observed in the XRD pattern even after higher concentration of doping (x = 0.100) of Zn. FESEM study revealed that the films are homogeneous without cracks and pinholes. TEM micrographs revealed the particles are slightly agglomerated and lesser than 25 nm. The optical absorption study revealed that pure and doped CdTe films possess a direct band gap material with bandgap values between 2.39 and 2.63 eV (±0.02 eV). The values of optical bandgap increase with an increase in dopant (Zn) concentration from x = 0.025 to 0.10. The pure cadmium telluride (CdTe) nanocrystalline film shows a strong green emission peak centered at about 525 nm. The emission peaks of Cd1-xZnxTe nanocrystalline films are red shifted from 525 nm to 611 nm according to the dopant (Zn2+) concentration. The grains in the prepared films are uniformly distributed, which was confirmed by narrow full width at half maximum (FWHM) of the emission peaks (40-65 nm). The DC conductivity has increased by 1.25 and 4 orders as the concentration of dopant increases from x = 0.025 to 0.10 at room temperature (30 °C) and 150 °C respectively. The higher conductivity value is underpinned by the smaller activation energy value and is explained by thermionic emission mechanism.

  11. Kardar-Parisi-Zhang universality, anomalous scaling and crossover efects in the growth of CdTe thin films

    OpenAIRE

    Almeida, Renan Augusto Lisbôa

    2015-01-01

    A relation between the mound evolution and large-wavelength fluctuations at CdTe surface has been established. One finds that short-length scales are dictated by an interplay between the effects of the for- mation of defects at colided boundaries of neighboring grains and a relaxation process which stems from the diffusion and deposition of particles (CdTe molecules) torward these regions. A Kinetic Monte Carlo model corroborates these reasonings. As T is increased, that competition gives ris...

  12. Epitaxial growth of CdTe oriented thin films, infrared characterization and possible applications to photo-voltaic cells

    OpenAIRE

    Gerbaux, X.; Pianelli, A.; Hadni, A.; Jeanniard, C.; Strimer, P.

    1980-01-01

    The growth of CdTe oriented thin films by the ENSH method - i.e. Epitaxial Nucleation in Sub-microscopic Holes of an intermediate layer closely applied on a bulk single crystal — has been recently described. The CdTe films are generally difficult to detach from the bulk crystal. However free films are needed to study the infrared transmission in the spectral region of high absorption. To get them, the vitreous or amorphous thin intermediate layers are substituted by quite soluble an oriented ...

  13. Optical and electrical characterizations of highly efficient CdTe thin film solar cells prepared by close-spaced sublimation

    Science.gov (United States)

    Okamoto, T.; Yamada, A.; Konagai, M.

    2000-06-01

    The effects of the Cu diffusion on the optical and electrical properties of CdTe thin film solar cells prepared by close-spaced sublimation (CSS) were investigated by capacitance-voltage ( C- V) measurement and low-temperature photoluminescence (PL) measurement. C- V measurement revealed that the net acceptor concentration in the CdTe layer was independent of the heat treatment after screen printing of the Cu-doped graphite electrode for Cu diffusion into the CdTe layer, although it greatly affected the solar cell performance. Furthermore, the depth profile of PL spectrum of CdTe layer implies that the heat treatment for Cu diffusion facilitates the formation of low-resistance contact to CdTe through the formation of a heavily doped (p +) region in the CdTe adjacent to the back electrode, but Cu atoms do not act as effective acceptors in the CdTe layer except the region near the back electrode.

  14. films using atomic layer deposition

    Science.gov (United States)

    Chervinskii, Semen; Matikainen, Antti; Dergachev, Alexey; Lipovskii, Andrey A.; Honkanen, Seppo

    2014-08-01

    We fabricated self-assembled silver nanoisland films using a recently developed technique based on out-diffusion of silver from an ion-exchanged glass substrate in reducing atmosphere. We demonstrate that the position of the surface plasmon resonance of the films depends on the conditions of the film growth. The resonance can be gradually shifted up to 100 nm towards longer wavelengths by using atomic layer deposition of titania, from 3 to 100 nm in thickness, upon the film. Examination of the nanoisland films in surface-enhanced Raman spectrometry showed that, in spite of a drop of the surface-enhanced Raman spectroscopy (SERS) signal after the titania spacer deposition, the Raman signal can be observed with spacers up to 7 nm in thickness. Denser nanoisland films show slower decay of the SERS signal with the increase in spacer thickness.

  15. Thin film CdTe solar cells with an absorber layer thickness in micro- and sub-micrometer scale

    Science.gov (United States)

    Bai, Zhizhong; Yang, Jun; Wang, Deliang

    2011-10-01

    CdTe thin film solar cell with an absorber layer as thin as 0.5 μm was fabricated. An efficiency of 7.9% was obtained for a 1-μm-thick CdTe solar cell. An increased intensity of deep recombination states in the band gap, which was responsible for the reduced open-circuit voltage and fill factor for ultra-thin solar cells, was induced due to the not-well-developed polycrystalline CdTe microstructure and the CdS/CdTe heterojunction and the presence of Cu in the back contact. The experimental results presented in this study demonstrated that 1-μm-thick absorber layer is thick enough to fabricate CdTe solar cell with a decent efficiency.

  16. The activation of thin film CdTe solar cells using alternative chlorine containing compounds

    Energy Technology Data Exchange (ETDEWEB)

    Maniscalco, B., E-mail: B.Maniscalco@lboro.ac.uk [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering (United Kingdom); Abbas, A.; Bowers, J.W.; Kaminski, P.M.; Bass, K. [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering (United Kingdom); West, G. [Department of Materials, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Walls, J.M. [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering (United Kingdom)

    2015-05-01

    The re-crystallisation of thin film cadmium telluride (CdTe) using cadmium chloride (CdCl{sub 2}) is a vital process for obtaining high efficiency photovoltaic devices. However, the precise micro-structural mechanisms involved are not well understood. In this study, we have used alternative chlorine-containing compounds to determine if these can also assist the re-crystallisation of the CdTe layer and to understand the separate roles of cadmium and chlorine during the activation. The compounds used were: tellurium tetrachloride (TeCl{sub 4}), cadmium acetate (Cd(CH{sub 3}CO{sub 2}){sub 2}), hydrochloric acid (HCl) and zinc chloride (ZnCl{sub 2}). TeCl{sub 4} was used to assess the role of Cl and the formation of a Te-rich outer layer which may assist the formation of the back contact. (Cd(CH{sub 3}CO{sub 2}){sub 2}) and HCl were used to distinguish between the roles of cadmium and chlorine in the process. Finally, ZnCl{sub 2} was employed as an alternative to CdCl{sub 2}. We report on the efficacy of using these alternative Cl-containing compounds to remove the high density of planar defects present in untreated CdTe. - Highlights: • Cadmium chloride (CdCl{sub 2}) activation treatment • Alternative chlorine containing compounds • Microstructure analysis and electrical performances.

  17. Characterization of intermixing at the CdS/CdTe interface in CSS deposited CdTe

    Science.gov (United States)

    Dhere, R. G.; Asher, S. E.; Jones, K. M.; Al-Jassim, M. M.; Moutinho, H. R.; Rose, D. H.; Dippo, P.; Sheldon, P.

    1996-01-01

    CdS/CdTe structures deposited on different substrates are analyzed using transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), optical transmission, atomic force microscopy (AFM), X-ray diffraction (XRD) and photoluminescence (PL). The microstructure of CdTe was found to be independent of CdS crystallinity, and the structural defects at CdS/CdTe interface are generated principally by the lattice mismatch between CdS and CdTe. The interdiffusion at the CdS/CdTe interface was found to be a function of substrate temperature and CdCl2 heat treatment.

  18. Nanofriction properties of molecular deposition films

    Institute of Scientific and Technical Information of China (English)

    王强斌; 高芒来; 张嗣伟

    2000-01-01

    The nanofriction properties of Au substrate and monolayer molecular deposition film and multilayer molecular deposition films on Au substrate and the molecular deposition films modified with alkyl-terminal molecule have been investigated by using an atomic force microscope. It is concluded that ( i ) the deposition of molecular deposition films on Au substrate and the modification of alkyl-terminal molecule to the molecular deposition films can reduce the frictional force; (ii) the molecular deposition films with the same terminal exhibit similar nanofriction properties, which has nothing to do with the molecular chain-length and the layer number; (iii) the unstable nanofriction properties of molecular deposition films are contributed to the active terminal of the molecular deposition film, which can be eliminated by decorating the active molecular deposition film with alkyl-terminal molecule, moreover, the decoration of alkyl-terminal molecule can lower the frictional force conspicuously; (iv) the relat

  19. Degradation of ultrathin CdTe films with SWCNT or Graphene back contact

    Science.gov (United States)

    Gorji, Nima E.

    2015-06-01

    The degradation of ultrathin film solar cells based on CdS/CdTe materials and back contacted with nanolayers are analysed using SCAPS. The ultrathin films suffer from uncompleted photo-absorption and fast degradation. The instability in performance was mainly attributed to the back contact materials which cause roll-over and cause mobile ions inter-diffusion. Thus, in this work, three different nanolayers such as single walled carbon nanotubes and Graphene are considered as the metal-free back contacts with wide controllable work function for the CdTe films. The simulations show that the roll-over in characteristics of the device disappears when the work function of the nanolayer increases by a proper doping. The current density-voltage curves showed promising results when the CdTe thickness was thinned down to 0.7 μm. Surface coverage of the grain boundaries at the interface of CdTe/nanolayer can reduce the contact series resistance and improve the carrier collection. However, the inter-sheet resistance of the nanolayers should be re-optimized. Finally, the time dependent approach was applied to simulate the defect generation under stress condition where the Cu-doped nanolayers showed faster degradation while the nanolayer back contacted devices showed higher stability.

  20. Thin Films with Low Zn Content Prepared by Chemical Bath Deposition

    Directory of Open Access Journals (Sweden)

    Caijuan Tian

    2012-01-01

    Full Text Available Chemical bath deposition (CBD was used for the growth of thin films with low Zn content. The influence of preparation conditions, such as pH, temperature, and concentration, on film properties was investigated. The chemical growth mechanism of thin films was analyzed, and optimized growth conditions for the thin films were established. The fill factor and short-circuit current were improved while was used to replace CdS as the window layer in CdTe solar cells.

  1. Nitric-phosphoric acid etching effects on the surface chemical composition of CdTe thin film.

    Science.gov (United States)

    Irfan, Irfan; Ding, Huanjun; Xia, Wei; Lin, Hao; Tang, Ching W.; Gao, Yongli

    2009-03-01

    Nitric-phosphoric (NP) acid etching has been regarded as one of the most successful methods for the formation of low resistance back contact with the metal electrode in CdTe based solar cells. We report back surface chemical composition for eight different durations of NP etching of CdTe polycrystalline thin film. We studied the surfaces with x-ray photoemission spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), inverse photoemission spectroscopy (IEPS) and atomic force microscopy (AFM). Etching dependence on the back surface composition and electronic structure was observed. Valence and conduction band shifts relative to the Fermi level of the system with different etching duration were analyzed. The sample was left in open ambient condition for three weeks and XPS data were obtained again in order to study the difference in surface chemical composition with the pristine CdTe film. Unetched and highly etched part of the sample were sputtered and the depth profile analyzed.

  2. Preparation and Characterization of RF Magntron Sputtering CdTe Thin Film%CdTe薄膜的射频磁控溅射制备及表征

    Institute of Scientific and Technical Information of China (English)

    王波; 张静全; 王生浩; 冯良桓; 雷智; 武莉莉; 李卫; 黎兵; 曾广根

    2011-01-01

    The cadmium telluride thin film was deposited on glass substrate at room teperature by RF magnetron sputtering. The film was characterized to show the variation of its properties with the diverse deposition conditions by X-ray diffraction, UV-VIS spectrometer, scanning electrical microscope, etc. The result indicates that thc deposition speed increases with the increase of deposition power and decreases with the increase of pressure. As the pressure decreases, the CdTe film' s crystallinity gets worse. It is found that the cubic crystalline structure of deposited sample changes to the crystalline hexagonal CdTe phase as the power increased from 100 W to140 W. While the CdTe thin films is deposited under the pressure of 0.3 Pa, with the power of 100 W and at room temperature, the crystallinity is the best and the band gap is 1.45 eV.%采用射频磁控溅射技术制备了Cdre薄膜,使用探针式台阶仪、X射线衍射分析仪、紫外可见分光光度计、扫描电镜等表征了薄膜的厚度、结构、透过率、表面形貌等随溅射工艺的变化.结果表明:沉积速率随着功率的增加而增加,随气压的增加而呈线性减小;薄膜的结晶程度随气压增大而降低;功率从100W增大到180 W,出现了CdTe薄膜晶相从立方相向六方相的转变;当沉积条件为纯氩气氛、气压0.3Pa、功率100W、室温时,沉积的CdTe薄膜结晶性能最好.

  3. SCAPS Modeling for Degradation of Ultrathin CdTe Films: Materials Interdiffusion

    Science.gov (United States)

    Houshmand, Mohammad; Zandi, M. Hossein; Gorji, Nima E.

    2015-09-01

    Ultrathin film solar cells based on CdS/CdTe ( d CdTe ≤ 1 µm) suffer from two main issues: incomplete photo absorption and high degradation rate. The former is cured by light-trapping techniques, whereas the latter is a matter of fabrication details. Interdiffusion of the material components and formation of subsequent interlayers at the front/back region can change the optical/electrical properties and performance/stability of the device. We model the degradation of the ultrathin CdTe film devices considering the material interdiffusion and interlayers formation: CdTeS, CdZnTe, Cu x Te (i.e., Te/Cu bilayer), and oxide interlayers (i.e., CdTeO3). The diffusion rate of the materials is considered separately and the reactions that change the interlayer's properties are studied. Additionally, a back contact of single-walled carbon nanotube showed a higher stability than the metallic contacts. A new time-dependent approach is applied to simulate the degradation rate due to formation of any interlayer. It is shown that the materials interdiffusion causes a defect increment under thermal stress and illumination. The metallic back contact accelerates the degradation, whereas single-walled carbon nanotubes show the highest stability. A SCAPS simulator was used because of its ability in defining the properties of the back contact and metastabilities at the interface layers. The properties of the layers were taken from the experimental data reported in the literature.

  4. Rectification and tunneling effects enabled by Al{sub 2}O{sub 3} atomic layer deposited on back contact of CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Jun; Lin, Qinxian; Li, Hao; Su, Yantao; Yang, Xiaoyang; Wu, Zhongzhen; Zheng, Jiaxin; Wang, Xinwei; Lin, Yuan; Pan, Feng, E-mail: panfeng@pkusz.edu.cn [School of Advanced Materials, Peking University Shenzhen Graduate School, Peking University, Shenzhen 518055 (China)

    2015-07-06

    Atomic layer deposition (ALD) of Aluminum oxide (Al{sub 2}O{sub 3}) is employed to optimize the back contact of thin film CdTe solar cells. Al{sub 2}O{sub 3} layers with a thickness of 0.5 nm to 5 nm are tested, and an improved efficiency, up to 12.1%, is found with the 1 nm Al{sub 2}O{sub 3} deposition, compared with the efficiency of 10.7% without Al{sub 2}O{sub 3} modification. The performance improvement stems from the surface modification that optimizes the rectification and tunneling of back contact. The current-voltage analysis indicates that the back contact with 1 nm Al{sub 2}O{sub 3} maintains large tunneling leakage current and improves the filled factor of CdTe cells through the rectification effect. XPS and capacitance-voltage electrical measurement analysis show that the ALD-Al{sub 2}O{sub 3} modification layer features a desired low-density of interface state of 8 × 10{sup 10 }cm{sup −2} by estimation.

  5. Development of high-efficiency, thin-film CdTe solar cells. Annual subcontract report, January 1, 1993--December 31, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Rohatgi, A.; Chou, H.C.; Kamra, S.; Bhat, A. [Georgia Institute of Technology, Atlanta, GA (United States)

    1994-09-01

    Polycrystalline thin film CdTe solar cells are one of the leading candidates for terrestrial photovoltaic applications. Theoretical calculations project an efficiency of 27% for single crystal, single junction CdTe cells, and the practically achievable efficiency for polycrystalline CdTe cells is 18-20%. Polycrystalline CdTe cells made by different groups show a significant variation in short circuit currents, open circuit voltages, and cell efficiencies. A better understanding of carrier loss and transport mechanism is crucial for explaining these differences, improving the yield, and bridging the gap between current and practically achievable limits in CdTe cell efficiencies. The goal of this program is to improve the understanding of the loss mechanisms in thin film CdS/CdTe solar cells and to improve their efficiency by characterizing the properties of the films as well as the finished devices.

  6. Improvement of the crystallinity of CdTe epitaxial film grown on Si substrates by molecular beam epitaxy using the two-step growth method

    Energy Technology Data Exchange (ETDEWEB)

    Han, M.S.; Ryu, Y.S.; Song, B.K.; Kang, T.W. [Dongguk Univ., Seoul (Korea, Republic of). Dept. of Phys.; Kim, T.W. [Department of Physics, Kwangwoon University, Seoul 139-701 (Korea, Republic of)

    1997-01-05

    Molecular beam epitaxy growth of CdTe epitaxial layers on Si (100) substrates using the two-step growth method was performed to produce high-quality CdTe thin layers. The reflection high-energy electron diffraction patterns were streaky with clear Kikuchi lines, which is direct evidence for layer-by-layer two-dimensional growth of CdTe on Si. From the X-ray diffraction analysis, the grown layer was found to be a CdTe (111) epitaxial film, regardless of the film thickness. Photoluminescence (PL) measurements at 12 K showed that the defect density of the CdTe film grown on Si using two-step growth decreased in comparison with that grown using direct growth. The bound exciton appearing in the PL measurements shifted to the low energy side as the thickness of the CdTe increased. When the CdTe thickness increased from 1 to 1.8 {mu}m, the peak position of the bound exciton shifted by 7.2 meV, and the stress obtained from the exciton peak shift was -12.405 kbar. These results indicate that high quality CdTe films grown by two-step growth hold promise for applications as buffer layers for the subsequent growth of Hg{sub x}Cd{sub 1-x}Te. (orig.) 16 refs.

  7. Enhanced electrical properties at boundaries including twin boundaries of polycrystalline CdTe thin-film solar cells.

    Science.gov (United States)

    Li, H; Liu, X X; Lin, Y S; Yang, B; Du, Z M

    2015-05-07

    The effect of grain boundaries (GBs), in particular twin boundaries (TBs), on CdTe polycrystalline thin films is studied by conductive atomic force microscopy (C-AFM), electron-beam-induced current (EBIC), scanning Kelvin probe microscopy (SKPM), electron backscatter diffraction (EBSD), and scanning transmission electron microscopy (STEM). Four types of CdTe grains with various densities of {111} Σ3 twin boundaries (TBs) are found in Cl-treated CdTe polycrystalline thin films: (1) grains having multiple {111} Σ3 TBs with a low angle to the film surface; (2) grains having multiple {111} Σ3 TBs parallel to the film surfaces; (3) small grains on a scale of not more than 500 nm, composed of Cd, Cl, Te, and O; and (4) CdTe grains with not more than two {111} Σ3 TBs. Grain boundaries (including TBs) exhibit enhanced current transport phenomena. However, the {111} Σ3 TB is much more beneficial to micro-current transport. The enhanced current transport can be explained by the lower electron potential at GBs (including TBs) than the grain interiors (GIs). Our results open new opportunities for enhancing solar cell performances by controlling the grain boundaries, and in particular TBs.

  8. Nanogoniometry with scanning force microscopy: a model study of CdTe thin films.

    Science.gov (United States)

    Palacios-Lidón, Elisa; Guanter, Luis; Zúñiga-Pérez, Jesús; Muñoz-Sanjosé, Vicente; Colchero, Jaime

    2007-03-01

    In this paper scanning force microscopy is combined with simple but powerful data processing to determine quantitatively, on a sub-micrometer scale, the orientation of surface facets present on crystalline materials. A high-quality scanning force topography image is used to determine an angular histogram of the surface normal at each image point. In addition to the known method for the assignment of Miller indices to the facets appearing on the surface, a quantitative analysis is presented that allows the characterization of the relative population and morphological quality of each of these facets. Two different CdTe thin films are used as model systems to probe the capabilities of this method, which enables further information to be obtained about the thermodynamic stability of particular crystallographic facets. The method, which is referred to as nanogoniometry, will be a powerful tool to study in detail the surface of crystalline materials, particularly thin films, with sub-micrometer resolution.

  9. Roughness of CdTe thin films grown on glass by hot wall epitaxy.

    Science.gov (United States)

    Leal, F F; Ferreira, S O; Menezes-Sobrinho, I L; Faria, T E

    2005-01-12

    Cadmium telluride films were grown on glass substrates using the hot wall epitaxy (HWE) technique. The samples were polycrystalline with a preferential (111) orientation. Scanning electron micrographs reveal a grain size between 0.1 and 0.5 µm. The surface morphology of the samples was studied by measuring the roughness profile using a stylus profiler. The roughness as a function of growth time and scale size were investigated to determine the growth and roughness exponents, β and α, respectively. From the results we can conclude that the growth surface has a self-affine character with a roughness exponent α equal to 0.69 ± 0.03 and almost independent of growth time. The growth exponent β was equal to 0.38 ± 0.06. These values agree with that determined previously for CdTe(111) films grown on GaAs(100).

  10. Optical properties of swift ion beam irradiated CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chandramohan, S. [PG and Research Department of Physics, Kongunadu Arts and Science College, Coimbatore, Tamilnadu 641029 (India); Sathyamoorthy, R. [PG and Research Department of Physics, Kongunadu Arts and Science College, Coimbatore, Tamilnadu 641029 (India)], E-mail: rsathya59@yahoo.co.in; Sudhagar, P. [PG and Research Department of Physics, Kongunadu Arts and Science College, Coimbatore, Tamilnadu 641029 (India); Kanjilal, D.; Kabiraj, D.; Asokan, K. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2008-06-30

    This paper reports the effect of swift (80 MeV) oxygen (O{sup +6}) ion irradiation on the optical properties of CdTe thin films grown by conventional thermal evaporation on glass substrates. The films are found to be slightly Te-rich in composition and irradiation results no change in the elemental composition. The optical constants such as refractive index (n), absorption coefficient ({alpha}) and the optical band gap energy show significant variation in their values with increase in ion fluence. Upon irradiation the band gap energy decreased from a value of 1.53 eV to 1.46 eV whereas the refractive index (n) increased from 2.38 to 3.12 at {lambda} = 850 nm. The photoluminescence spectrum shows high density of native defects whose density strongly depends on the ion fluence. Both analyses indicate considerable defect production after swift ion beam irradiation.

  11. Studies of key technologies for CdTe solar modules

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, CdS thin films, which act as the window layer and n-type partner to the p-type CdTe layer, were prepared by chemical bath deposition (CBD). CdTe thin films were deposited by the close-spaced sublimation (CSS) method. To obtain high-quality back contacts, a Te-rich layer was created with chemical etching and back contact materials were applied after CdTe annealing. The results indicate that the ZnTe/ZnTe:Cu complex layers show superior performance over other back contacts. Finally, by using laser scribing and mechanical scribing, the CdTe mini-modules were fabricated, in which a glass/SnO2:F/CdS/CdTe/ZnTe/ZnTe:Cu/Ni solar module with a PWQC-confirmed total-area efficiency of 7.03% (54 cm2) was achieved.

  12. CdTe Thin Film Solar Cells and Modules Tutorial; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    Albin, David S.

    2015-06-13

    This is a tutorial presented at the 42nd IEEE Photovoltaics Specialists Conference to cover the introduction, background, and updates on CdTe cell and module technology, including CdTe cell and module structure and fabrication.

  13. Electro-Plating and Characterisation of CdTe Thin Films Using CdCl2 as the Cadmium Source

    OpenAIRE

    Nor A. Abdul-Manaf; Hussein I. Salim; Mohammad L. Madugu; Olajide I. Olusola; Imyhamy M. Dharmadasa

    2015-01-01

    Cadmium telluride (CdTe) thin films have been successfully prepared from an aqueous electrolyte bath containing cadmium chloride (CdCl2)·H2O and tellurium dioxide (TeO2) using an electrodeposition technique. The structural, electrical, morphological and optical properties of these thin films have been characterised using X-ray diffraction (XRD), Raman spectroscopy, optical profilometry, DC current-voltage (I-V) measurements, photoelectrochemical (PEC) cell measurement, scanning electron micr...

  14. Dynamic effects in CdTe quantum-dot LEDs

    OpenAIRE

    Gallardo, D. E.

    2006-01-01

    In this work the electrical and electroluminescence properties CdTe nanocrystal films were analysed. The structure consisted of a multilayer of CdTe nanocrystals deposited by the layer-by-layer technique, sandwiched between an ITO anode and an aluminium cathode. The first part of this work was dedicated to structural and process improvement. Earlier devices, produced through a layer-by-layer (LbL) manual procedure, had an average thickness of 30nm per nanocrystal monolayer,...

  15. CdTe Photovoltaics for Sustainable Electricity Generation

    Science.gov (United States)

    Munshi, Amit; Sampath, Walajabad

    2016-09-01

    Thin film CdTe (cadmium telluride) is an important technology in the development of sustainable and affordable electricity generation. More than 10 GW of installations have been carried out using this technology around the globe. It has been demonstrated as a sustainable, green, renewable, affordable and abundant source of electricity. An advanced sublimation tool has been developed that allows highly controlled deposition of CdTe films onto commercial soda lime glass substrates. All deposition and treatment steps can be performed without breaking the vacuum within a single chamber in an inline process that can be conveniently scaled to a commercial process. In addition, an advanced cosublimation source has been developed to allow the deposition of ternary alloys such as Cd x Mg1- x Te to form an electron reflector layer which is expected to address the voltage deficits in current CdTe devices and to achieve very high efficiency. Extensive materials characterization, including but not limited to scanning electron microscopy, transmission electron microscopy, energy dispersive x-ray spectroscopy, high resolution transmission electron microscopy and electron back-scatter diffraction, has been performed to get a better understanding of the effects of processing conditions on CdTe thin film photovoltaics. This combined with computer modeling such as density function theory modeling gives a new insight into the mechanism of CdTe photovoltaic function. With all these efforts, CdTe photovoltaics has seen great progress in the last few years. Currently, it has been recorded as the cheapest source of electricity in the USA on a commercial scale, and further improvements are predicted to further reduce the cost while increasing its utilization. Here, we give an overview of the advantages of thin film CdTe photovoltaics as well as a brief review of the challenges that need to be addressed. Some fundamental studies of processing conditions for thin film CdTe are also presented

  16. Recrystallization of PVD CdTe Thin Films Induced by CdCl2 Treatment -- A Comparison Between Vapor and Solution Processes: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Mountinho, H. R.; Dhere, R. G.; Romero, M. J.; Jiang, C. S.; To, B.; Al-Jassim, M. M.

    2008-05-01

    This paper describes the large concentration of 60..deg.. <111> twin boundaries that was observed in every CdTe film analyzed in this work, even after recrystallization and grain growth, confirming the low energy of these interfaces.

  17. a Cdlts Study of the Deep Levels in n- and P - Cadmium Telluride Thin Films Deposited by Hot Wall Evaporation

    Science.gov (United States)

    Ginting, Masno

    CdTe thin films, both undoped and with different dopants, have been deposited unto graphite and Corning 7059 glass substrates using a Three-Stage Hot Wall Vacuum Evaporator (TSHWVE) system. The dopants were incorporated into the CdTe thin films using a "delta doping" technique. The conductivity type of the doped CdTe thin films was determined using the hot probe method, and the film stoichiometry was determined using X-ray and Auger electron spectroscopy measurements. Schottky diodes fabricated on the CdTe thin films that were deposited on graphite substrates have been studied using Current-Voltage (I-V), Capacitance-Voltage (C-V), and Capacitance Deep Level Transient Spectroscopy (CDLTS). The conductivity type of CdTe films that were undoped and doped with Antimony (Sb), Phosphorus (P), Gold (Au), Silver (Ag), and Copper (Cu) were found to be p-type, while Indium (In) doped CdTe thin films were found to be n-type. The highest carrier concentration of the CdTe films are 1 times 10^ {16} cm^{-3} , 1 times 10^ {17} cm^{-3} , and 7.5 times 10 ^{15} cm^{ -3} for In-, Sb-, and P-doped CdTe, respectively. For the In-doped CdTe films three majority carrier trap are found with activation energies measured from the conduction band of 0.23 +/- 0.05 eV, 0.46 +/- 0.06 eV, and 0.78 +/- 0.05 eV. For the Sb-doped CdTe films three majority carrier traps are found with activation energies measured from the valence band of 0.27 +/- 0.06 eV, 0.50 +/- 0.06 eV, and 0.80 +/- 0.06 eV. For the P-doped CdTe films three majority carrier traps are found with activation energies measured from the valence band of 0.28 +/- 0.05 eV, 0.50 +/- 0.06 eV and 0.75 +/- 0.05 eV. Our capture measurements on In-, Sb-, and P-doped CdTe showed non-exponential transients, however they could be fitted very well by Pons theory, and allowed us to determine values for the trap concentration (N_{ rm T}), the trap capture rate (c _{rm n,p}) and the trap capture cross-section (sigma_{rm n,p}). However, the capture

  18. In-depth analysis of chloride treatments for thin-film CdTe solar cells

    Science.gov (United States)

    Major, J. D.; Al Turkestani, M.; Bowen, L.; Brossard, M.; Li, C.; Lagoudakis, P.; Pennycook, S. J.; Phillips, L. J.; Treharne, R. E.; Durose, K.

    2016-10-01

    CdTe thin-film solar cells are now the main industrially established alternative to silicon-based photovoltaics. These cells remain reliant on the so-called chloride activation step in order to achieve high conversion efficiencies. Here, by comparison of effective and ineffective chloride treatments, we show the main role of the chloride process to be the modification of grain boundaries through chlorine accumulation, which leads an increase in the carrier lifetime. It is also demonstrated that while improvements in fill factor and short circuit current may be achieved through use of the ineffective chlorides, or indeed simple air annealing, voltage improvement is linked directly to chlorine incorporation at the grain boundaries. This suggests that focus on improved or more controlled grain boundary treatments may provide a route to achieving higher cell voltages and thus efficiencies.

  19. Anomalous scaling and super-roughness in the growth of CdTe polycrystalline films

    Science.gov (United States)

    Mata, Angélica S.; Ferreira, Silvio C., Jr.; Ribeiro, Igor R. B.; Ferreira, Sukarno O.

    2008-09-01

    CdTe films grown on glass substrates covered by fluorine-doped tin oxide by hot-wall epitaxy were studied through the interface dynamical scaling theory. Direct measures of the dynamical exponent revealed an intrinsically anomalous scaling characterized by a global roughness exponent α , distinct from the local one (the Hurst exponent H ) previously reported by Ferreira [Appl. Phys. Lett.88, 244103 (2006)]. A variety of scaling behaviors was obtained with varying substrate temperature. In particular, a transition from an intrinsically anomalous scaling regime with H≠αrough regime with H≠α>1 at high temperatures was observed. The temperature is a growth parameter that controls both the interface roughness and dynamical scaling exponents. Nonlocal effects are pointed out as the factors ruling the anomalous scaling behavior.

  20. Synthesis and properties of 10% Zn layered CdTe thin films by SEL method

    Science.gov (United States)

    Shanmugan, S.; Mutharasu, D.

    2011-10-01

    Te/Cd/Te/Zn/Cd stacked layers were prepared by Stacked Elemental Layer (SEL) Method. All stacks were annealed from 200 °C to 500 °C and the prepared films were confirmed as polycrystalline nature. Cubic CdTe and Hexagonal ZnTe were identified at high annealing temperature. Transmittance spectra emphasized the significance of Zn doping by annealing the stack. The calculated optical constants n and k were 1.52-2.45 and 0.07-0.36 respectively. The band gaps (Eg) were observed between 1.38 and 1.44 eV at above 350 °C. A uniform surface morphology could be observed at high annealing temperatures. The observed results encouraged the Zn doping using SEL method.

  1. Development of high-efficiency, thin-film CdTe solar cells. Final subcontract report, 1 February 1992--30 November 1995

    Energy Technology Data Exchange (ETDEWEB)

    Rohatgi, A.; Chou, H.C.; Kamra, S.; Bhat, A. [Georgia Inst. of Tech., Atlanta, GA (United States)

    1996-01-01

    This report describes work performed by the Georgia Institute of Technology (GIT) to bring the polycrystalline CdTe cell efficiency a step closer to the practically achievable efficiency of 18% through fundamental understanding of detects and loss mechanisms, the role of chemical and heat treatments, and investigation of now process techniques. The objective was addressed by a combination of in-depth characterization, modeling, materials growth, device fabrication, and `transport analyses of Au/Cu/CdTe/CdS/SnO {sub 2} glass front-wall heterojunction solar cells. GiT attempted to understand the loss mechanism(s) in each layer and interface by a step-by-step investigation of this multilayer cell structure. The first step was to understand, quantify, and reduce the reflectance and photocurrent loss in polycrystalline CdTe solar calls. The second step involved the investigation of detects and loss mechanisms associated with the CdTe layer and the CdTe/CdS interface. The third stop was to investigate the effect of chemical and heat treatments on CdTe films and cells. The fourth step was to achieve a better and reliable contact to CdTe solar cells by improving the fundamental understanding. Of the effects of Cu on cell efficiency. Finally, the research involved the investigation of the effect of crystallinity and grain boundaries on Cu incorporation in the CdTe films, including the fabrication of CdTe solar calls with larger CdTe grain size.

  2. Research Leading to High Throughput Manufacturing of Thin-Film CdTe PV Modules: Annual Subcontract Report, September 2004--September 2005

    Energy Technology Data Exchange (ETDEWEB)

    Powell, R. C.

    2006-04-01

    Specific overall objectives of this subcontract are improvement in baseline field performance of manufactured CdTe PV modules while reducing environmental, health and safety risk in the manufacturing environment. Project objectives focus on four broad categories: (1) development of advanced front-contact window layers, (2) improved semiconductor film deposition, (3) development of improved accelerated life test procedures that indicate baseline field performance, and (4) reduction of cadmium-related environmental, health and safety risks. First Solar has significantly increased manufacturing capacity from less than 2 MW/yr to more than 20 MW/yr, while increasing the average module total-area power conversion efficiency from 7% to >9%. First Solar currently manufactures and sells 50-65-W thin-film CdTe PV modules at a rate of about 1.9 MW/month. Sales backlog (booked sales less current inventory divided by production rate) is more than a year. First Solar is currently building new facilities and installing additional equipment to increase production capacity by 50 MW/yr; the additional capacity is expected to come on line in the third quarter of 2006.

  3. CdTe thin film solar cells. Optimization of material, morphology and device preparation

    Energy Technology Data Exchange (ETDEWEB)

    Schaffner, J.; Barati, A.; Krishnakumar, V.; Fu, G.; Schimper, H.J.; Haindl, A.; Swirschuk, A.; Gunnesch, E.; Schneikart, A.; Tueschen, A.; Klein, A.; Jaegermann, W. [Technische Univ. Darmstadt (Germany). Fachbereich Materialwissenschaft

    2010-07-01

    Correlations between layer-morphology and electrical properties are shown. At substrate temperatures between 330 C and 380 C the layer-morphology is similar to that obtained at the typically used high temperatures above 500 C. First results showed promising efficiencies for growth temperatures around 350 C. With optimized layer-morphology, dense, pinhole-free layers can be achieved. With a CdTe thickness below 3 {mu}m and CdS layers thinner than 100 nm, each of them deposited by a two step process using two different substrate temperatures, efficiencies of more than 10% were reached. For ANTEC CdS/CdTe cells, alternative back contacts were made in an all-dry vacuum process without any need for wet chemical etching. Cell efficiencies close to the efficiencies obtained with wet processing (NP etching and Au back contact) were obtained. This was achieved without the use of highly diffusive copper. (orig.)

  4. Fabrication of stable large-area thin-film CdTe photovoltaic modules. Annual subcontract report, 10 May 1992--9 May 1993

    Energy Technology Data Exchange (ETDEWEB)

    Nolan, J.F.; Meyers, P.V. [Solar Cells, Inc., Toledo, OH (United States)

    1993-08-01

    This report highlights the progress made by Solar Cells, Inc. (SCI), in its program to produce 60-cm {times} 120-cm solar modules based on CdTe films. During the past year, confirmed efficiency has increased to 10.4% (active area) on a 1 cm{sup 2} cell, 9.8% (aperture area) on a 64-cm{sup 2} 8-cell submodule, and 6.6% (total area) on a 7200-cm{sup 2} module. A module measured in-house had a power output of 53 W, for a total-area efficiency of 7.4%. Average efficiency of modules produced is steadily increasing and standard deviation is decreasing; in a limited run of 12 modules, results were 6.3% ({plus_minus} 0.2%). Field testing has begun; a nominal 1-kW array of 24 modules was set up adjacent to SCI`s facilities. Analysis indicates that present modules are limited in efficiency by shunt resistance and optical absorption losses in the glass superstrate. Loss analysis of present devices allows us to project a module efficiency of 11.8%. A third generation deposition method -- atmospheric pressure elemental vapor deposition (APEVD) has been brought on-line and has produced good quality CdTe. In addition, SCI is expanding its proactive safety, health, environmental, and disposal program dealing with issues surrounding cadmium.

  5. Influence of Deposition Conditions on Properties of All Sputtered CdS/CdTe Thin-Film Solar Cells.

    Science.gov (United States)

    Kim, Minha; Kim, Doyoung; Shim, Joong-Pyo; Kim, Donguk; Lee, Jaehyeong

    2016-05-01

    The effects of deposition conditions, such as substrate temperature and CdCl2 post treatments, on the structural and optical properties of CdTe films were investigated. In addition, CdS/CdTe thin-film solar cells were fabricated by an all-sputtering process, and their photovoltaic characteristics were studied. The CdTe films had a polycrystalline, cubic structure with a preferred orientation of the [1 1 1] direction parallel to the substrate surface, regardless of the substrate temperature. As the substrate temperature increased, the crystallinity of CdTe films improved. The grain size of the CdTe films increased after CdCl2 post treatment. In addition, the optical band gap increased with the substrate temperature. The conversion efficiency of the CdS/CdTe solar cell improved at higher substrate temperatures. The maximum efficiency, 9.23%, was obtained at a substrate temperature of 400 degrees C, with an open-circuit voltage (V(oc)) of 0.78 V, a short-circuit current density (J(sc)) of 20.4 mA/cm2, and a fill factor of 0.58.

  6. CdTe:Ge/Si (100) thin films grown by pulsed laser deposition (PLD) for photonic devices

    Science.gov (United States)

    Neretina, S.; Hughes, R. A.; Preston, J. S.; Sochinskii, N. V.; Mascher, P.

    2005-09-01

    Cadmium Telluride (CdTe) is a well known photonic material in the fields of infrared imaging and solar cells. Its nonlinear optical properties also make it a promising candidate for novel telecom applications that would utilize its high Kerr coefficient to produce advanced logical devices such as switches, routers and wavelength converters. The large photorefractive effect observed in CdTe also makes possible high-speed devices suitable for optical data processing. In order to advance such photorefractive waveguide applications, we have deposited CdTe films on silicon substrates with a native oxide layer using the pulsed laser deposition technique (PLD). Silicon was chosen as the substrate material as it is suitable for the monolithic integration of logical devices. Maintaining an oxide layer was deemed necessary as a high refractive index mismatch is desirable for high-index contrast waveguide based applications and such an index mismatch could be provided by a reasonably thick layer of SiO2. Films exhibiting some structural deficiencies, but with high optical quality were deposited through the optimization of the growth parameters. X-ray diffraction data indicates that the films are [111] oriented with rocking curves of substantial width. Atomic force microscopy images confirm that the films have a smooth surface morphology as was suggested by their mirror-like appearance. Using the optimum growth conditions, CdTe films doped with germanium were also deposited as this dopant introduces deep donor levels that enhance the photorefractive effect. A comparison of the optical properties obtained from the doped and undoped films indicate that impurities can have a marked effect on the index of refraction and extinction coefficient. Such alterations to the optical constants must be considered in the design of waveguide structures.

  7. CdTe devices and method of manufacturing same

    Energy Technology Data Exchange (ETDEWEB)

    Gessert, Timothy A.; Noufi, Rommel; Dhere, Ramesh G.; Albin, David S.; Barnes, Teresa; Burst, James; Duenow, Joel N.; Reese, Matthew

    2015-09-29

    A method of producing polycrystalline CdTe materials and devices that incorporate the polycrystalline CdTe materials are provided. In particular, a method of producing polycrystalline p-doped CdTe thin films for use in CdTe solar cells in which the CdTe thin films possess enhanced acceptor densities and minority carrier lifetimes, resulting in enhanced efficiency of the solar cells containing the CdTe material are provided.

  8. The growth of CdTe thin film by close space sublimation system

    Science.gov (United States)

    Alamri, S. N.

    2003-12-01

    The effects of source and substrate temperature, ambient gas pressure and the separation between source and substrate on the growth rate of CdTe using the close space sublimation (CSS) system have been investigated. The growth rate increased as the source temperature increased with an activation energy of 1.9 eV and it was constant and independent of the substrate temperature, up to some breakpoint temperature, above which the rate decreased rapidly to zero. Free sublimation and transport is involved at low pressures such as 7.5 × 10-5 mbar, whereas diffusion-limited transport was involved at pressures of 2 and 6 mbar of N2. The growth rate increased as the separation between the source and the substrate decreased. The film's grain size increased from <1 m at 335 °C to more than 2.5 m at above 445 °C. Analysis of the XRD traces indicated that the films grown at 335 °C were a highly preferred (111) orientation and the (111) texture coefficient reduced when the substrate temperature increased. (

  9. Stoichiometry dependence of the optical and minority-carrier lifetime behaviors of CdTe epitaxial films: A low-temperature and time-resolved photoluminescence study

    Science.gov (United States)

    Tang, Kai; Zhu, Xuanting; Zhu, Liangqing; Bai, Wei; Bai, Jiawei; Dong, Wenxia; Yang, Jing; Zhang, Yuanyuan; Chen, Ye; Tang, Xiaodong; Chu, Junhao

    2016-11-01

    Cadmium telluride (CdTe) epitaxial films (EFs) were grown on near-lattice-matched Cd0.96Zn0.04Te (CZT) substrates by molecular beam epitaxy at different ambients to achieve Cd-rich samples with extra Cd molecular flux or Te-rich samples with extra Te molecular flux. The evolution of epitaxial growth was in situ monitored by reflection high-energy electron diffraction (RHEED). A two-dimensional growth mode was indicated by the streaky RHEED patterns. Crystal structures of the CdTe EFs were characterised by X-ray diffraction (XRD). XRD data suggested that the crystal quality of the CdTe EFs was improved by controlling the Cd and Te flux ratio. Low-temperature photoluminescence (PL) spectra were carried out in these CdTe EFs. The typical characteristic peak at ∼1.552 eV denoted as the bound-to-free transition was only found in CdTe samples grown under an extra Cd flux, and Cd vacancy-related defects were absent in the Cd-rich EFs, confirming the Cd-rich or Te-rich states of the epitaxial CdTe films. Finally, minority-carrier lifetime was prolonged in Cd-rich CdTe EFs as supported by time-resolved photoluminescence (TRPL) measurement.

  10. Pulsed laser deposition: Prospects for commercial deposition of epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Muenchausen, R.E.

    1999-03-01

    Pulsed laser deposition (PLD) is a physical vapor deposition (PVD) technique for the deposition of thin films. The vapor source is induced by the flash evaporation that occurs when a laser pulse of sufficient intensity (about 100 MW/cm{sup 2}) is absorbed by a target. In this paper the author briefly defines pulsed laser deposition, current applications, research directed at gaining a better understanding of the pulsed laser deposition process, and suggests some future directions to enable commercial applications.

  11. Thin film growth of a topological crystal insulator SnTe on the CdTe (111) surface by molecular beam epitaxy

    Science.gov (United States)

    Ishikawa, Ryo; Yamaguchi, Tomonari; Ohtaki, Yusuke; Akiyama, Ryota; Kuroda, Shinji

    2016-11-01

    We report molecular beam epitaxial growth of a SnTe (111) layer on a CdTe template, fabricated by depositing it on a GaAs (111)A substrate, instead of BaF2 which has been conventionally used as a substrate. By optimizing temperatures for the growth of both SnTe and CdTe layers and the SnTe growth rate, we could obtain SnTe layers of the single phase grown only in the (111) orientation and of much improved surface morphology from the viewpoint of the extension and the flatness of flat regions, compared to the layers grown on BaF2. In this optimal growth condition, we have also achieved a low hole density of the order of 1017 cm-3 at 4 K, the lowest value ever reported for SnTe thin films without additional doping. In the magnetoresistance measurement on this optimized SnTe layer, we observe characteristic negative magneto-conductance which is attributed to the weak antilocalization effect of the two-dimensional transport in the topological surface state.

  12. Fabrication of CdTe solar cells by laser-driven physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Compaan, A.; Bhat, A.; Tabory, C.; Liu, S.; Nguyen, M.; Aydinli, A.; Tsien, L.H.; Bohn, R.G. (Toledo Univ., OH (USA). Dept. of Physics and Astronomy)

    1991-05-01

    Polycrystalline cadmium sulfide-cadmium telluride heterojunction solar cells were fabricated for the first time using a laser-driven physical vapor deposition method. An XeCl excimer laser was used to deposit both of the II-VI semiconductor layers in a single vacuum chamber from pressed powder targets. Results are presented from optical absorption. Raman scattering, X-ray diffraction, and electrical characterization of the films. Solar cells were fabricated by deposition onto SnO{sub 2}-coated glass with top contacts produced by gold evaporation. Device performance was evaluated from the spectral quantum efficiency and current-voltage measurements in the dark and with air mass 1.5 solar illumination. (orig.).

  13. Wiring-up carbon single wall nanotubes to polycrystalline inorganic semiconductor thin films: low-barrier, copper-free back contact to CdTe solar cells.

    Science.gov (United States)

    Phillips, Adam B; Khanal, Rajendra R; Song, Zhaoning; Zartman, Rosa M; DeWitt, Jonathan L; Stone, Jon M; Roland, Paul J; Plotnikov, Victor V; Carter, Chad W; Stayancho, John M; Ellingson, Randall J; Compaan, Alvin D; Heben, Michael J

    2013-11-13

    We have discovered that films of carbon single wall nanotubes (SWNTs) make excellent back contacts to CdTe devices without any modification to the CdTe surface. Efficiencies of SWNT-contacted devices are slightly higher than otherwise identical devices formed with standard Au/Cu back contacts. The SWNT layer is thermally stable and easily applied with a spray process, and SWNT-contacted devices show no signs of degradation during accelerated life testing.

  14. Electrodeposition, characterization and photo electrochemical properties of CdSe and CdTe

    Directory of Open Access Journals (Sweden)

    Atef Y. Shenouda

    2015-03-01

    Full Text Available CdSe and CdTe are electrodeposited using 0.1 M Cd2+ and different ion concentrations of Se and Te. The effect of the temperature on the electrodeposition process is also studied. The crystal structure of the deposited CdSe and CdTe is investigated by X-ray diffraction (XRD. Scanning electron microscopy (SEM of samples deposited at optimized parameters reveals that CdSe has spongy spherical grains while CdTe has coralloid morphology. Optical absorption shows the presence of direct transition with band gap energy 1.96 and 1.51 eV for CdSe and CdTe, respectively. The highest photo-conversion efficiencies of electrodeposited CdSe and CdTe films per unit area are 6% and 9.6%, respectively that achieved under simple laboratory conditions.

  15. Growth and characterization of CdTe on GaAs/Si substrates

    Science.gov (United States)

    Radhakrishnan, G.; Nouhi, A.; Liu, J.

    1988-01-01

    Epitaxial CdTe has been grown on both (100) GaAs/Si and (111) GaAs/Si substrates. A combination of molecular beam epitaxy and metal organic chemical vapor deposition have been employed to achieve this growth. The GaAs layers are grown in Si substrates by molecular beam epitaxy, followed by the growth of CdTe on GaAs/Si substra by metalorganic chemical vapor deposition. X-ray diffraction, photoluminescence, and scanning electron microscopy have been used to characterize the CdTe films.

  16. Energetic deposition of thin metal films

    CERN Document Server

    Al-Busaidy, M S K

    2001-01-01

    deposited films. The primary aim of this thesis was to study the physical effect of energetic deposition metal thin films. The secondary aim is to enhance the quality of the films produced to a desired quality. Grazing incidence X-ray reflectivity (GIXR) measurements from a high-energy synchrotron radiation source were carried out to study and characterise the samples. Optical Profilers Interferometery, Atomic Force Microscope (AFM), Auger electron spectroscopy (AES), Medium energy ion spectroscopy (MEIS), and the Electron microscope studies were the other main structural characterisation tools used. AI/Fe trilayers, as well as multilayers were deposited using a Nordico planar D.C. magnetron deposition system at different voltage biases and pressures. The films were calibrated and investigated. The relation between energetic deposition variation and structural properties was intensely researched. Energetic deposition refers to the method in which the deposited species possess higher kinetic energy and impact ...

  17. On the interpretation of {sup 57}Fe Moessbauer spectra from CdTe thin films with substitutions of Fe, In, and Sb

    Energy Technology Data Exchange (ETDEWEB)

    Yee-Madeira, H. [Centro de Investigacion y de Estudios Avanzados, IPN, Mexico City (Mexico). Dept. de Fisica]|[Depto. de Fisica, Esc. Sup. de Fisica y Matematicas (ESFM) del IPN, Edif. 9, U. P. ALM, 07738, Mexico D.F. (Mexico); Reguera, E.; Zelaya-Angel, O.; Sanchez-Sinencio, F. [Centro de Investigacion y de Estudios Avanzados, IPN, Mexico City (Mexico). Dept. de Fisica; Montiel-Sanchez, H. [Depto. de Fisica, Esc. Sup. de Fisica y Matematicas (ESFM) del IPN, Edif. 9, U. P. ALM, 07738, Mexico D.F. (Mexico); Scorzelli, R.B. [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150, CEP 22290, Urca, Rio de Janeiro (Brazil)

    1999-02-26

    {sup 57}Fe Moessbauer spectra of well characterized CdTe thin films with substitutions of Fe, In and Sb were recorded and interpreted according to the changes in the ionic radii and electronic properties of these substitutions relative to Cd in the CdTe framework. The literature reports of certain correlations among the iron valence, Fe{sup 2+} or Fe{sup 3+}, and the crystallinity of the films are critically discussed and an explanation of their origin is provided. The Moessbauer results also allow direct understanding of the effect of In and Sb substitutions on the properties of the films. (orig.) 22 refs.

  18. Electrochemical Behaviour of Sputtering Deposited DLC Films

    Institute of Scientific and Technical Information of China (English)

    LIU Erjia; ZENG A,LIU L X

    2003-01-01

    Diamondlike carbon (DLC) films were deposited via magnetron sputtering process. The energetic ion bombardment on the surface of growing film is one of the major parameters that control the atom mobility on the film surface and further the physical and chemical characteristics of the films. In this study, the energy of carbon ions was monitored by changing sputtering power density, and its effect on the electrochemical performance of the films was investigated. For the deposition at a higher sputtering power density, a higher sp3 content in the DLC films was achieved with denser structure and increased film-substrate adhesion. The impedance at the interface of Si substrate/sulfuric acid solution was significantly enhanced, and at the same time higher film resistance, lower capacitance, higher breakdown potential and longer breakdown time were observed, which were related to the significant sp3 content of the DLC films.

  19. Te-doped cadmium telluride films fabricated by close spaced sublimation

    Science.gov (United States)

    Li, J.; Zheng, Y. F.; Xu, J. B.; Dai, K.

    2003-07-01

    Te-doped cadmium telluride (CdTe) films were deposited on ITO/glass substrates using the close spaced sublimation (CSS) method. The films were characterized by x-ray diffraction (XRD), the x-ray fixed-quantity (XRF) method, scanning electron microscopy (SEM) and the Hall effect. The XRD and SEM results show that appropriate Te doping would be favourable to the growth of CdTe crystallite. The Hall effect measurements indicate that the conductivity of CdTe films could be dramatically improved by Te doping. The work presented here suggests that p-type doping CdTe films can be produced using this deposition method.

  20. Optimization of the front contact to minimize short-circuit current losses in CdTe thin-film solar cells

    Science.gov (United States)

    Kephart, Jason Michael

    With a growing population and rising standard of living, the world is in need of clean sources of energy at low cost in order to meet both economic and environmental needs. Solar energy is an abundant resource which is fundamentally adequate to meet all human energy needs. Photovoltaics are an attractive way to safely convert this energy to electricity with little to no noise, moving parts, water, or arable land. Currently, thin-film photovoltaic modules based on cadmium telluride are a low-cost solution with multiple GW/year commercial production, but have lower conversion efficiency than the dominant technology, crystalline silicon. Increasing the conversion efficiency of these panels through optimization of the electronic and optical structure of the cell can further lower the cost of these modules. The front contact of the CdTe thin-film solar cell is critical to device efficiency for three important reasons: it must transmit light to the CdTe absorber to be collected, it must form a reasonably passive interface and serve as a growth template for the CdTe, and it must allow electrons to be extracted from the CdTe. The current standard window layer material, cadmium sulfide, has a low bandgap of 2.4 eV which can block over 20% of available light from being converted to mobile charge carriers. Reducing the thickness of this layer or replacing it with a higher-bandgap material can provide a commensurate increase in device efficiency. When the CdS window is made thinner, a degradation in electronic quality of the device is observed with a reduction in open-circuit voltage and fill factor. One commonly used method to enable a thinner optimum CdS thickness is a high-resistance transparent (HRT) layer between the transparent conducting oxide electrode and window layer. The function of this layer has not been fully explained in the literature, and existing hypotheses center on the existence of pinholes in the window layer which are not consistent with observed results

  1. Effect of Substrate Temperature on CdTe Thin Film Property and Solar Cell Performance%衬底温度对碲化镉薄膜性质及太阳电池性能的影响

    Institute of Scientific and Technical Information of China (English)

    曹胜; 武莉莉; 冯良桓; 王文武; 张静全; 郁骁骑; 李鑫鑫; 李卫; 黎兵

    2016-01-01

    Vapor transport deposition is an excellent method for preparing large area CdTe thin films with high quality and uniformity. Polycrystalline CdTe thin films were deposited by home-made vapor transport deposition system (VTD). The effects of substrate temperature on the property of CdTe film and the performance of CdTe solar cell were inves-tigated. CdTe thin films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), UV-Vis spectrometer, and Hall Effect system. The results show that the CdTe thin films deposited by vapor transport deposi-tion are cubic phase with a preferred orientation in (111) direction. The average grain size increases from 2mm to 6mm and the carrier concentration increases from 1.93×1010 cm–3 to 2.36×1013 cm–3 when the substrate temperature increases from 520 ℃ to 620 ℃. This suggests that high substrate temperature can increase the carrier density significantly due to the suppressed defect recombination. The performance of CdTe thin film solar cells deposited at different sub-strate temperatures demonstrates that high substrate temperature (610℃) can greatly improve the efficiency, open cir-cuit voltage and fill factor of the solar cells. But the substrate temperature higher than 610℃ will reduce the spectral response of the cells in long wavelength region, which results in the degradation of solar cell performance. The small-area CdTe thin film solar cell without back contact layer deposited at substrate temperature of 610℃ obtains the best conversion efficiency of 11.2%.%蒸汽输运法是制备高质量且大面积均匀的 CdTe 薄膜的一种优良的方法。采用自主研发的一套蒸汽输运沉积系统制备了 CdTe 多晶薄膜,并研究了衬底温度对 CdTe 薄膜性质及太阳电池性能的影响。利用 XRD、SEM、UV-Vis和Hall等测试手段研究了衬底温度对薄膜的结构、光学性质和电学性质的影响。结果表明,蒸汽输运法制备的CdTe薄

  2. Effects of processing temperature on the thickness of CdS and the performance of CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ferekides, C.S.; Tetali, B.; Marinskiy, D.; Marinskaya, S.; Morel, D. [Department of Electrical Engineering, Center for Clean Energy and Vehicles, University of South Florida, Tampa, Florida 33620 (United States)

    1997-02-01

    CdTe cells have been fabricated on soda lime glass substrates. The effect of the CdS thickness and CdTe deposition temperature on the spectral response (SR) and solar cell parameters has been studied. The CdTe deposition temperature has been found to be a key processing parameter in determining the extent of interdiffusion at the CdTe and CdS interface. When the deposition of CdTe is carried out at high temperatures a significant portion of the CdS films is {open_quotes}lost{close_quotes} due to interdiffusion which leads to enhancement of the blue response of the solar cells. Devices with identical blue response (400{endash}500 nm) have been fabricated even though the starting CdS thicknesses were different; the cells for which the starting CdS thickness was greater exhibited higher open-circuit voltages and fill factors. {copyright} {ital 1997 American Institute of Physics.}

  3. Highly Luminescent Hybrid SiO2-Coated CdTe Quantum Dots Retained Initial Photoluminescence Efficiency in Sol-Gel SiO2 Film.

    Science.gov (United States)

    Sun, Hongsheng; Xing, Yugui; Wu, Qinan; Yang, Ping

    2015-02-01

    A highly luminescent silica film was fabricated using tetraethyl orthosilicate (TEOS) and 3-aminopropyltrimethoxysilane (APS) through a controlled sol-gel reaction. The pre-hydrolysis of TEOS and APS which resulted in the mixture of TEOS and APS in a molecular level is a key for the formation of homogenous films. The aminopropyl groups in APS play an important role for obtaining homogeneous film with high photoluminescence (PL). Red-emitting hybrid SiO2-coated CdTe nano-crystals (NCs) were fabricated by a two-step synthesis including a thin SiO2 coating via a sol-gel process and a subsequent refluxing using green-emitting CdTe NCs. The hybrid SiO2-coated CdTe NCs were embedded in a functional SiO2 film via a two-step process including adding the NCs in SiO2 sol with a high viscosity and almost without ethanol and a subsequent spinning coating. The hybrid SiO2-coated CdTe NCs retained their initial PL efficiency (54%) in the film. Being encapsulated with the hybrid NCs in the film, no change on the absorption and PL spectra of red-emitting CdTe NCs (632 nm) was observed. This indicates the hybrid NCs is stable enough during preparation. This phenomenon is ascribed to the controlled sol-gel process and a hybrid SiO2 shell on CdTe NCs. Because these films exhibited high PL efficiency and stability, they will be utilizable for potential applications in many fields.

  4. Thin Film & Deposition Systems (Windows)

    Data.gov (United States)

    Federal Laboratory Consortium — Coating Lab: Contains chambers for growing thin film window coatings. Plasma Applications Coating Lab: Contains chambers for growing thin film window coatings. Solar...

  5. Electrochemical Behaviour of Sputtering Deposited DLC Films

    Institute of Scientific and Technical Information of China (English)

    LIUErjia; ZENGA; LIULX

    2003-01-01

    Diamondlike carbon (DLC) films were deposited via magnetron sputtering process. The energetic ion hombardment on the surface of growing film is one of the major parameters that control the atom mobility on the flirt1 surface and further the physical and chemical characteristics of the films. In this study, the energy of carbon ions was monitored by changing sputtering powerdensity, and its effect on the electrochemical performance of the films was investigated. For the deposition at a higher sputtering power density, a higher sp3 content in the DLC films was achieved with denser structure and increased film-substrate adhesion. The impedance at the interface of Si substrate/sulfufic acid solution was significantly enhanced, and at the same time higher film resistance, lower capacitance, higher breakdown potential and longer breakdown time were observed, which were related to the significant sp3 content of the DLC films.

  6. Deposition of polycrystalline Cd{sub 1-x}Zn{sub x} Te films on ZnTe/graphite and graphite substrates by close-spaced sublimation

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Tamotsu; Akiba, Sho; Takahashi, Kohei; Nagatsuka, Satsuki; Kanda, Yohei [Department of Electrical and Electronic Engineering, Kisarazu National College of Technology, 2-11-1 Kiyomidai-higashi, Kisarazu, Chiba 292-0041 (Japan); Tokuda, Satoshi; Kishihara, Hiroyuki; Sato, Toshiyuki [Technology Research Laboratory, Shimadzu Corporation, 3-9-4 Hikaridai, Seika-cho, Soraku-gun, Kyoto 619-0237 (Japan)

    2014-07-15

    The effects of a ZnTe layer on the deposition of a Cd{sub 1-x}Zn{sub x}Te (CZT) layer in the initial stage of the close-spaced sublimation (CSS) deposition were investigated. The deposition rate was almost constant in the initial stage of the CdTe deposition on the ZnTe/graphite substrates. However, the deposition rate within 1 minute was lower than that after 1 minute in the CdTe deposition on graphite substrates. This result suggests that nucleation of CdTe directly deposited on graphite substrate is difficult when compared to that with a ZnTe layer. Furthermore, the effects of CdCl{sub 2} and ZnTe additions to the CdTe sources in the CSS deposition were also investigated. Both the grain size and the intensity of donor-acceptor pair (DAP) emission in photoluminescence (PL) spectra were decreased by the effect of CdCl{sub 2} addition. Zn content in CZT films was controlled by the ZnTe ratio in the CdTe/ZnTe powder sources. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Spatial luminescence imaging of dopant incorporation in CdTe Films

    Science.gov (United States)

    Guthrey, Harvey; Moseley, John; Colegrove, Eric; Burst, James; Albin, David; Metzger, Wyatt K.; Al-Jassim, Mowafak

    2017-01-01

    State-of-the-art cathodoluminescence (CL) spectrum imaging with spectrum-per-pixel CL emission mapping is applied to spatially profile how dopant elements are incorporated into Cadmium telluride (CdTe). Emission spectra and intensity monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on computational modeling. Our results show that grain boundaries play a role in incorporating dopants in CdTe exposed to copper, phosphorus, and intrinsic point defects in CdTe. The image analysis provides critical, unique feedback to understand dopant incorporation and activation in the inhomogeneous CdTe material, which has struggled to reach high levels of hole density.

  8. Spatial luminescence imaging of dopant incorporation in CdTe Films

    Energy Technology Data Exchange (ETDEWEB)

    Guthrey, Harvey; Moseley, John; Colegrove, Eric; Burst, James; Albin, David; Metzger, Wyatt K.; Al-Jassim, Mowafak

    2017-01-28

    State-of-the-art cathodoluminescence (CL) spectrum imaging with spectrum-per-pixel CL emission mapping is applied to spatially profile how dopant elements are incorporated into Cadmium telluride (CdTe). Emission spectra and intensity monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on computational modeling. Our results show that grain boundaries play a role in incorporating dopants in CdTe exposed to copper, phosphorus, and intrinsic point defects in CdTe. The image analysis provides critical, unique feedback to understand dopant incorporation and activation in the inhomogeneous CdTe material, which has struggled to reach high levels of hole density.

  9. Photoconductivity of CdTe Nanocrystal-Based Thin Films. Te2- Ligands Lead To Charge Carrier Diffusion Lengths Over 2 Micrometers

    Energy Technology Data Exchange (ETDEWEB)

    Crisp, Ryan W. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Callahan, Rebecca [National Renewable Energy Lab. (NREL), Golden, CO (United States); Reid, Obadiah G. [Univ. of Colorado, Boulder, CO (United States); Dolzhnikov, Dmitriy S. [Univ. of Chicago, IL (United States); Talapin, Dmitri V. [Univ. of Chicago, IL (United States); Rumbles, Garry [National Renewable Energy Lab. (NREL), Golden, CO (United States); Luther, Joseph M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Kopidakis, Nikos [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2015-11-16

    We report on photoconductivity of films of CdTe nanocrystals (NCs) using time-resolved microwave photoconductivity (TRMC). Spherical and tetrapodal CdTe NCs with tunable size-dependent properties are studied as a function of surface ligand (including inorganic molecular chalcogenide species) and annealing temperature. Relatively high carrier mobility is measured for films of sintered tetrapod NCs (4 cm2/(V s)). Our TRMC findings show that Te2- capped CdTe NCs show a marked improvement in carrier mobility (11 cm2/(V s)), indicating that NC surface termination can be altered to play a crucial role in charge-carrier mobility even after the NC solids are sintered into bulk films.

  10. Photoconductivity of CdTe Nanocrystal-Based Thin Films: Te(2-) Ligands Lead To Charge Carrier Diffusion Lengths Over 2 μm.

    Science.gov (United States)

    Crisp, Ryan W; Callahan, Rebecca; Reid, Obadiah G; Dolzhnikov, Dmitriy S; Talapin, Dmitri V; Rumbles, Garry; Luther, Joseph M; Kopidakis, Nikos

    2015-12-03

    We report on photoconductivity of films of CdTe nanocrystals (NCs) using time-resolved microwave photoconductivity (TRMC). Spherical and tetrapodal CdTe NCs with tunable size-dependent properties are studied as a function of surface ligand (including inorganic molecular chalcogenide species) and annealing temperature. Relatively high carrier mobility is measured for films of sintered tetrapod NCs (4 cm(2)/(V s)). Our TRMC findings show that Te(2-) capped CdTe NCs show a marked improvement in carrier mobility (11 cm(2)/(V s)), indicating that NC surface termination can be altered to play a crucial role in charge-carrier mobility even after the NC solids are sintered into bulk films.

  11. Analysis of the electrodeposition and surface chemistry of CdTe, CdSe, and CdS thin films through substrate-overlayer surface-enhanced Raman spectroscopy.

    Science.gov (United States)

    Gu, Junsi; Fahrenkrug, Eli; Maldonado, Stephen

    2014-09-02

    The substrate-overlayer approach has been used to acquire surface enhanced Raman spectra (SERS) during and after electrochemical atomic layer deposition (ECALD) of CdSe, CdTe, and CdS thin films. The collected data suggest that SERS measurements performed with off-resonance (i.e. far from the surface plasmonic wavelength of the underlying SERS substrate) laser excitation do not introduce perturbations to the ECALD processes. Spectra acquired in this way afford rapid insight on the quality of the semiconductor film during the course of an ECALD process. For example, SERS data are used to highlight ECALD conditions that yield crystalline CdSe and CdS films. In contrast, SERS measurements with short wavelength laser excitation show evidence of photoelectrochemical effects that were not germane to the intended ECALD process. Using the semiconductor films prepared by ECALD, the substrate-overlayer SERS approach also affords analysis of semiconductor surface adsorbates. Specifically, Raman spectra of benzenethiol adsorbed onto CdSe, CdTe, and CdS films are detailed. Spectral shifts in the vibronic features of adsorbate bonding suggest subtle differences in substrate-adsorbate interactions, highlighting the sensitivity of this methodology.

  12. Effects of CdTe growth conditions and techniques on the efficiency limiting defects and mechanisms in CdTe solar cells

    Science.gov (United States)

    Rohatgi, A.; Chou, H. C.; Jokerst, N. M.; Thomas, E. W.; Ferekides, C.; Kamra, S.; Feng, Z. C.; Dugan, K. M.

    1996-01-01

    CdTe solar cells were fabricated by depositing CdTe films on CdS/SnO2/glass substrates using close-spaced sublimation (CSS) and metalorganic chemical vapor deposition (MOCVD). Te/Cd mole ratio was varied in the range of 0.02 to 6 in the MOCVD growth ambient in an attempt to vary the native defect concentration. Polycrystalline CdTe layers grown by MOCVD and CSS both showed average grain size of about 2 μm. However, the CdTe films grown by CSS were found to be less faceted and more dense compared to the CdTe grown by MOCVD. CdTe growth techniques and conditions had a significant impact on the electrical characteristics of the cells. The CdTe solar cells grown by MOCVD in the Te-rich growth condition and by the CSS technique gave high cell efficiencies of 11.5% and 12.4%, respectively, compared to 6.6% efficient MOCVD cells grown in Cd-rich conditions. This large difference in efficiency is explained on the basis of (a) XRD measurements which showed a higher degree of atomic interdiffusion at the CdS/CdTe interface in high performance devices, (b) Raman measurements which endorsed more uniform and preferred grain orientation by revealing a sharp CdTe TO mode in the high efficiency cells, and (c) carrier transport mechanism which switched from tunneling/interface recombination to depletion region recombination in the high efficiency cells. In this study, Cu/Au layers were evaporated on CdTe for the back contact. Lower efficiency of the Te-rich MOCVD cells, compared to the CSS cells, was attributed to contact related additional loss mechanisms, such as Cd pile-up near Cu/CdTe interface which can give rise to Cd-vacancy defects in the bulk, and higher Cu concentration in the CdTe layer which can cause shunts in the device. Finally, SIMS measurements on the CdTe films of different crystallinity and grain size confirmed that grain boundaries are the main conduits for Cu migration into the CdTe film. Thus larger CdTe grain size or lower grain boundary area per unit volume

  13. High rate deposition of thin film cadmium sulphide by pulsed direct current magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Lisco, F., E-mail: F.Lisco@lboro.ac.uk [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Kaminski, P.M.; Abbas, A.; Bowers, J.W.; Claudio, G. [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Losurdo, M. [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR, via Orabona 4, 70126 Bari (Italy); Walls, J.M. [Centre for Renewable Energy Systems Technology (CREST), School of Electronic, Electrical and Systems Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)

    2015-01-01

    Cadmium Sulphide (CdS) is an important n-type semiconductor widely used as a window layer in thin film photovoltaics Copper Indium Selenide, Copper Indium Gallium (di)Selenide, Copper Zinc Tin Sulphide and Cadmium Telluride (CdTe). Cadmium Sulphide has been deposited using a number of techniques but these techniques can be slow (chemical bath deposition and Radio Frequency sputtering) or the uniformity and the control of thickness can be relatively difficult (close space sublimation). In this paper we report on the development of a process using pulsed Direct Current magnetron sputtering which allows nanometre control of thin film thickness using time only. The CdS thin films deposited in this process are highly uniform and smooth. They exhibit the preferred hexagonal structure at room temperature deposition and they have excellent optical properties. Importantly, the process is highly stable despite the use of a semi-insulating magnetron target. Moreover, the process is very fast. The deposition rate using 1.5 kW of power to a 6-inch circular magnetron was measured to be greater than 8 nm/s. This makes the process suitable for industrial deployment. - Highlights: • Pulsed DC magnetron sputtering of CdS • High deposition rate deposition • Uniform, pinhole free films.

  14. Development of Combinatorial Pulsed Laser Deposition for Expedited Device Optimization in CdTe/CdS Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Ali Kadhim

    2016-01-01

    Full Text Available A combinatorial pulsed laser deposition system was developed by integrating a computer controlled scanning sample stage in order to rapidly screen processing conditions relevant to CdTe/CdS thin-film solar cells. Using this system, the thickness of the CdTe absorber layer is varied across a single sample from 1.5 μm to 0.75 μm. The effects of thickness on CdTe grain morphology, crystal orientation, and cell efficiency were investigated with respect to different postprocessing conditions. It is shown that the thinner CdTe layer of 0.75 μm obtained the best power conversion efficiency up to 5.3%. The results of this work shows the importance that CdTe grain size/morphology relative to CdTe thickness has on device performance and quantitatively exhibits what those values should be to obtain efficient thin-film CdTe/CdS solar cells fabricated with pulsed laser deposition. Further development of this combinatorial approach could enable high-throughput exploration and optimization of CdTe/CdS solar cells.

  15. Addendum to "Anomalous scaling and super-roughness in the growth of CdTe polycrystalline films"

    OpenAIRE

    Fábio S. Nascimento; Mata, Angélica S.; Ferreira, Silvio C.; Ferreira, Sukarno O.

    2011-01-01

    The scaling of the growth of CdTe films on glass substrates was investigated by Mata \\textit{et al.} [Phys. Rev. B \\textbf{78}, 115305 (2008)]. Part of the analysis consisted of the estimation of the correlation length $\\xi$ using the decay in the height-height correlation function. Afterwards, the dynamical exponent $z$ was determined using the scaling hypothesis $\\xi\\sim t^{1/z}$. In this Addendum, we show that the correlation lengths obtained by Mata \\textit{et al.} provide a long waveleng...

  16. Thin film CdTe based neutron detectors with high thermal neutron efficiency and gamma rejection for security applications

    Science.gov (United States)

    Smith, L.; Murphy, J. W.; Kim, J.; Rozhdestvenskyy, S.; Mejia, I.; Park, H.; Allee, D. R.; Quevedo-Lopez, M.; Gnade, B.

    2016-12-01

    Solid-state neutron detectors offer an alternative to 3He based detectors, but suffer from limited neutron efficiencies that make their use in security applications impractical. Solid-state neutron detectors based on single crystal silicon also have relatively high gamma-ray efficiencies that lead to false positives. Thin film polycrystalline CdTe based detectors require less complex processing with significantly lower gamma-ray efficiencies. Advanced geometries can also be implemented to achieve high thermal neutron efficiencies competitive with silicon based technology. This study evaluates these strategies by simulation and experimentation and demonstrates an approach to achieve >10% intrinsic efficiency with <10-6 gamma-ray efficiency.

  17. Characterization of Highly Efficient CdTe Thin Film Solar Cells by the Capacitance-Voltage Profiling Technique

    Science.gov (United States)

    Okamoto, Tamotsu; Yamada, Akira; Konagai, Makoto

    2000-05-01

    The electrical properties of highly efficient CdTe thin film solar cells prepared by close-spaced sublimation (CSS) were investigated by capacitance-voltage (C-V) measurement. According to the dependence of the cell performance on the substrate temperature in the CSS process, the open-circuit voltage (Voc) increased with increasing the substrate temperature below 630°C@. The carrier concentration profiles revealed that the net acceptor concentration exponentially increased from the CdS/CdTe interface to the rear and that the acceptor concentration increased with increasing substrate temperature. This result suggests that Voc is improved as a result of the increase in the acceptor concentration.

  18. Electroplating of CdTe Thin Films from Cadmium Sulphate Precursor and Comparison of Layers Grown by 3-Electrode and 2-Electrode Systems

    Directory of Open Access Journals (Sweden)

    Imyhamy M. Dharmadasa

    2017-01-01

    Full Text Available Electrodeposition of CdTe thin films was carried out from the late 1970s using the cadmium sulphate precursor. The solar energy group at Sheffield Hallam University has carried out a comprehensive study of CdTe thin films electroplated using cadmium sulfate, cadmium nitrate and cadmium chloride precursors, in order to select the best electrolyte. Some of these results have been published elsewhere, and this manuscript presents the summary of the results obtained on CdTe layers grown from cadmium sulphate precursor. In addition, this research program has been exploring the ways of eliminating the reference electrode, since this is a possible source of detrimental impurities, such as K+ and Ag+ for CdS/CdTe solar cells. This paper compares the results obtained from CdTe layers grown by three-electrode (3E and two-electrode (2E systems for their material properties and performance in CdS/CdTe devices. Thin films were characterized using a wide range of analytical techniques for their structural, morphological, optical and electrical properties. These layers have also been used in device structures; glass/FTO/CdS/CdTe/Au and CdTe from both methods have produced solar cells to date with efficiencies in the region of 5%–13%. Comprehensive work carried out to date produced comparable and superior devices fabricated from materials grown using 2E system.

  19. Advanced processing technology for high-efficiency, thin-film CuInSe{sub 2} and CdTe solar cells. Final subcontract report, March 1, 1992--April 30, 1995

    Energy Technology Data Exchange (ETDEWEB)

    Morel, D L; Ferekides, C S [University of South Florida, Tampa, FL (United States)

    1996-01-01

    This report describes work performed by the University of South Florida to develop a manufacturing-friendly fabrication process for CuInSe{sub 2} (CIS) solar cells. The process developed under this project uses conventional deposition processes and equipment, does not require stringent process control, and uses elemental Se as the selenium source. The authors believe it can be readily scaled up using off-the-shelf processing equipment and that it will meet the low manufacturing-cost objectives. Another significant achievement under this project was the development of a reactive sputtering deposition technology for ZnO. ZnO is used in many solar cell devices, and sputtering is a desirable manufacturing technology. The application of sputtering has been limited because conventional deposition uses ceramic targets that result in low sputtering rates. The use of Zn metal as the target in reactive sputtering overcomes this limitation. The authors have demonstrated that ZnO deposited by reactive sputtering has state-of-the-art opto-electronic properties. These developments result in large-area uniformity and optimized performance and provide a significant opportunity for applying and commercializing the technology. The second objective of this project was to fabricate high-efficiency CdTe solar cells using manufacturing-friendly processes. Three deposition processes were used to deposit CdS films: chemical bath deposition, rf sputtering, and close-spaced sublimation (CSS). The CdTe films were deposited by CSS. A cell with a record efficiency of 15.8% was obtained.

  20. Liquid phase deposition of electrochromic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Thomas J.; Rubin, Michael D.

    2000-08-18

    Thin films of titanium, zirconium and nickel oxides were deposited on conductive SnO2:F glass substrates by immersion in aqueous solutions. The films are transparent, conformal, of uniform thickness and appearance, and adhere strongly to the substrates. On electrochemical cycling, TiO2, mixed TiO2-ZrO2, and NiOx films exhibited stable electrochromism with high coloration efficiencies. These nickel oxide films were particularly stable compared with films prepared by other non-vacuum techniques. The method is simple, inexpensive, energy efficient, and readily scalable to larger substrates.

  1. Perovskite Thin Films via Atomic Layer Deposition

    KAUST Repository

    Sutherland, Brandon R.

    2014-10-30

    © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. (Graph Presented) A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3NH3PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm-1.

  2. Perovskite thin films via atomic layer deposition.

    Science.gov (United States)

    Sutherland, Brandon R; Hoogland, Sjoerd; Adachi, Michael M; Kanjanaboos, Pongsakorn; Wong, Chris T O; McDowell, Jeffrey J; Xu, Jixian; Voznyy, Oleksandr; Ning, Zhijun; Houtepen, Arjan J; Sargent, Edward H

    2015-01-01

    A new method to deposit perovskite thin films that benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3 NH3 PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm(-1) .

  3. Development of Combinatorial Pulsed Laser Deposition for Expedited Device Optimization in CdTe/CdS Thin-Film Solar Cells

    OpenAIRE

    Ali Kadhim; Paul Harrison; Jake Meeth; Alaa Al-Mebir; Guanggen Zeng; Judy Wu

    2016-01-01

    A combinatorial pulsed laser deposition system was developed by integrating a computer controlled scanning sample stage in order to rapidly screen processing conditions relevant to CdTe/CdS thin-film solar cells. Using this system, the thickness of the CdTe absorber layer is varied across a single sample from 1.5 μm to 0.75 μm. The effects of thickness on CdTe grain morphology, crystal orientation, and cell efficiency were investigated with respect to different postprocessing conditions. It i...

  4. Long Lifetime Hole Traps at Grain Boundaries in CdTe Thin-Film Photovoltaics

    Science.gov (United States)

    Mendis, B. G.; Gachet, D.; Major, J. D.; Durose, K.

    2015-11-01

    A novel time-resolved cathodoluminescence method, where a pulsed electron beam is generated via the photoelectric effect, is used to probe individual CdTe grain boundaries. Excitons have a short lifetime (≤100 ps ) within the grains and are rapidly quenched at the grain boundary. However, a ˜47 meV shallow acceptor, believed to be due to oxygen, can act as a long lifetime hole trap, even at the grain boundaries where their concentration is higher. This provides direct evidence supporting recent observations of hopping conduction across grain boundaries in highly doped CdTe at low temperature.

  5. Hard Carbon Films Deposited under Various Atmospheres

    Science.gov (United States)

    Wei, M.-K.; Chen, S.-C.; Wu, T. C.; Lee, Sanboh

    1998-03-01

    Using a carbon target ablated with an XeCl-excimer laser under various gas atmospheres at different pressures, hard carbon was deposited on silicon, iron and tungsten carbide substrates. The hardness, friction coefficient, and wear rate of the film against steel are better than pure substrate material, respectively, so that it has potential to be used as a protective coating for micromechanical elements. The influences of gas pressure, gas atmosphere, and power density of laser irradiation on the thermal stability of film were analyzed by means of Raman-spectroscope, time-of-flight method, and optical emission spectrum. It was found that the film deposited under higher pressure has less diamond-like character. The film deposited under rest gas or argon atmosphere was very unstable and looked like a little graphite-like character. The film deposited at high vacuum (10-5 mbar rest gas) was the most stable and looked like the most diamond-like character. The film deposited at higher power density was more diamond-like than that at lower power density.

  6. Band diagrams and performance of CdTe solar cells with a Sb2Te3 back contact buffer layer

    Directory of Open Access Journals (Sweden)

    Songbai Hu

    2011-12-01

    Full Text Available Sb2Te3 thin films were prepared by vacuum co-evaporation and the crystallinity of the films was greatly improved after annealing at 573 K in N2 ambient. Then they were deposited on the CdTe thick films. Band diagrams of the as-deposited and annealed CdTe/Sb2Te3 interfaces were constructed. Consequently, Sb2Te3 was used as a back contact layer for CdTe thin film solar cells and the cell performance was investigated. It was found that the Sb impurities accumulated in the CdTe grain boundaries diffuse deeply in the CdTe layer, and more photogenerated electrons and holes are separated by the segregated SbCd+ donors into the GBs. What is more, the doping concentration in the vicinity of the CdTe/CdS heterojunction increases for the formation of substitutional SbTe- acceptors under the Cd-rich conditions. For the introduction of the p-type Sb2Te3 layers as the back contact to the CdTe thin film solar cells, the performance of CdTe thin film solar cells has been greatly improved and an efficiency of 13.1% (FF=62.3%, Jsc=25.8 mA/cm2, Voc= 815.8 mV obtained.

  7. Thin-film CdTe detector for microdosimetric study of radiation dose enhancement at gold-tissue interface.

    Science.gov (United States)

    Paudel, Nava Raj; Shvydka, Diana; Parsai, E Ishmael

    2016-09-08

    Presence of interfaces between high and low atomic number (Z) materials, often encountered in diagnostic imaging and radiation therapy, leads to radiation dose perturbation. It is characterized by a very narrow region of sharp dose enhancement at the interface. A rapid falloff of dose enhancement over a very short distance from the interface makes the experimental dosimetry nontrivial. We use an in-house-built inexpensive thin-film Cadmium Telluride (CdTe) photodetector to study this effect at the gold-tissue interface and verify our experimental results with Monte Carlo (MC) modeling. Three-micron thick thin-film CdTe photodetectors were fabricated in our lab. One-, ten- or one hundred-micron thick gold foils placed in a tissue-equivalent-phantom were irradiated with a clinical Ir-192 high-dose-rate (HDR) source and current measured with a CdTe detector in each case was compared with the current measured for all uniform tissue-equivalent phantom. Percentage signal enhancement (PSE) due to each gold foil was then compared against MC modeled percentage dose enhancement (PDE), obtained from the geometry mimicking the experimental setup. The experimental PSEs due to 1, 10, and 100 μm thick gold foils at the closest measured distance of 12.5μm from the interface were 42.6 ± 10.8 , 137.0 ± 11.9, and 203.0 ± 15.4, respectively. The corresponding MC modeled PDEs were 38.1 ± 1, 164 ± 1, and 249 ± 1, respectively. The experimental and MC modeled values showed a closer agreement at the larger distances from the interface. The dose enhancement in the vicinity of gold-tissue interface was successfully measured using an in-house-built, high-resolution CdTe-based photodetector and validated with MC simulations. A close agreement between experimental and the MC modeled results shows that CdTe detector can be utilized for mapping interface dose distribution encountered in the application of ionizing radiation.

  8. Technology Support for High-Throughput Processing of Thin-Film CdTe PV Modules Annual Technical Report, Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Rose, D.H.; Powell, R.C.; Karpov, V.; Grecu, D.; Jayamaha, U.; Dorer, G.L. (First Solar, L.L.C.)

    2001-02-05

    Results and conclusions from Phase II of a three-year subcontract are presented. The subcontract, entitled Technology Support for High-Throughput Processing of Thin-Film CdTe PV Modules, is First Solar's portion of the Thin-Film Photovoltaic Partnership Program. The research effort of this subcontract is divided into four areas of effort: (1) process and equipment development, (2) efficiency improvement, (3) characterization and analysis, and (4) environmental, health, and safety. As part of the process and equipment development effort, a new semiconductor deposition system with a throughput of 3 m2/min was completed, and a production line in a new 75,000 ft2 facility was started and is near completion. As part of the efficiency-improvement task, research was done on cells and modules with thin CdS and buffer layers as way to increase photocurrent with no loss in the other photovoltaic characteristics. A number of activities were part of the characterization and analysis task, including developing a new admittance spectroscopy system, with a range of 0.001 Hz to 100 kHz, to characterize cells. As part of the environmental, health, and safety task, the methanol-based CdCl2 process was replaced with aqueous-CdCl2. This change enabled the retention of a De Minimus level of emissions for the manufacturing plant, so no permitting is required.

  9. Pulsed laser deposition of tantalum pentoxide film

    Science.gov (United States)

    Zhang, J.-Y.; Boyd, I. W.

    We report thin tantalum pentoxide (Ta2O5) films grown on quartz and silicon substrates by the pulsed laser deposition (PLD) technique employing a Nd:YAG laser (wavelength λ=532 nm) in various O2 gas environments. The effect of oxygen pressure, substrate temperature, and annealing under UV irradiation using a 172-nm excimer lamp on the properties of the grown films has been studied. The optical properties determined by UV spectrophotometry were also found to be a sensitive function of oxygen pressure in the chamber. At an O2 pressure of 0.2 mbar and deposition temperatures between 400 and 500 °C, the refractive index of the films was around 2.18 which is very close to the bulk Ta2O5 value of 2.2, and an optical transmittance around 90% in the visible region of the spectrum was obtained. X-ray diffraction measurements showed that the as-deposited films were amorphous at temperatures below 500 °C and possessed an orthorhombic (β-Ta2O5) crystal structure at temperatures above 600 °C. The most significant result of the present study was that oxygen pressure could be used to control the composition and modulate optical band gap of the films. It was also found that UV annealing can significantly improve the optical and electrical properties of the films deposited at low oxygen pressures (<0.1 mbar).

  10. Correlations of electro-optical and nanostructural properties of CdTe thin films

    Science.gov (United States)

    Levi, D. H.; Moutinho, H. R.; Hasoon, F. S.; Ahrenkiel, R. K.; Kazmerski, L. L.; Al-Jassim, M. M.

    1996-01-01

    This paper presents correlations of macroscopic optical properties with the nanoscale physical and electronic structure of CdTe/CdS thin films used for photovoltaic cell fabrication. We have studied the evolution of these properties under systematic variation of post-growth treatment conditions for several standard deposition techniques. The electro-optical properties and nanostructure depend strongly on deposition conditions and post-growth treatments. Our results indicate that the standard CdCl2—heat treatment enhances grain size and passivates defects. We have also found strong evidence for sulfur diffusion across the CdTe—CdS interface. This interdiffusion produces a thin layer at the junction with a bandgap lower than the rest of the absorber layer. This effect could have important implications for photoexcited carrier collection in photovoltaic applications.

  11. Correlations of electro-optical and nanostructural properties of CdTe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Levi, D.H.; Moutinho, H.R.; Hasoon, F.S.; Ahrenkiel, R.K.; Kazmerski, L.L.; Al-Jassim, M.M. [National Renewable Energy Laboratory, 1617 Cole Blvd., Golden, Colorado 80401 (United States)

    1996-01-01

    This paper presents correlations of macroscopic optical properties with the nanoscale physical and electronic structure of CdTe/CdS thin films used for photovoltaic cell fabrication. We have studied the evolution of these properties under systematic variation of post-growth treatment conditions for several standard deposition techniques. The electro-optical properties and nanostructure depend strongly on deposition conditions and post-growth treatments. Our results indicate that the standard CdCl{sub 2}{emdash}heat treatment enhances grain size and passivates defects. We have also found strong evidence for sulfur diffusion across the CdTe{emdash}CdS interface. This interdiffusion produces a thin layer at the junction with a bandgap lower than the rest of the absorber layer. This effect could have important implications for photoexcited carrier collection in photovoltaic applications. {copyright} {ital 1996 American Institute of Physics.}

  12. Effect of In Situ Thermal Annealing on Structural, Optical, and Electrical Properties of CdS/CdTe Thin Film Solar Cells Fabricated by Pulsed Laser Deposition

    Directory of Open Access Journals (Sweden)

    Alaa Ayad Al-mebir

    2016-01-01

    Full Text Available An in situ thermal annealing process (iTAP has been introduced before the common ex situ cadmium chloride (CdCl2 annealing to improve crystal quality and morphology of the CdTe thin films after pulsed laser deposition of CdS/CdTe heterostructures. A strong correlation between the two annealing processes was observed, leading to a profound effect on the performance of CdS/CdTe thin film solar cells. Atomic force microscopy and Raman spectroscopy show that the iTAP in the optimal processing window produces considerable CdTe grain growth and improves the CdTe crystallinity, which results in significantly improved optoelectronic properties and quantum efficiency of the CdS/CdTe solar cells. A power conversion efficiency of up to 7.0% has been obtained on thin film CdS/CdTe solar cells of absorber thickness as small as 0.75 μm processed with the optimal iTAP at 450°C for 10–20 min. This result illustrates the importance of controlling microstructures of CdTe thin films and iTAP provides a viable approach to achieve such a control.

  13. Iron films deposited on porous alumina substrates

    Science.gov (United States)

    Yamada, Yasuhiro; Tanabe, Kenichi; Nishida, Naoki; Kobayashi, Yoshio

    2016-12-01

    Iron films were deposited on porous alumina substrates using an arc plasma gun. The pore sizes (120 - 250 nm) of the substrates were controlled by changing the temperature during the anodic oxidation of aluminum plates. Iron atoms penetrated into pores with diameters of less than 160 nm, and were stabilized by forming γ-Fe, whereas α-Fe was produced as a flat plane covering the pores. For porous alumina substrates with pore sizes larger than 200 nm, the deposited iron films contained many defects and the resulting α-Fe had smaller hyperfine magnetic fields. In addition, only a very small amount of γ-Fe was obtained. It was demonstrated that the composition and structure of an iron film can be affected by the surface morphology of the porous alumina substrate on which the film is grown.

  14. Laser deposition of bimetallic island films

    Science.gov (United States)

    Kucherik, A. O.; Arakelyan, S. M.; Kutrovskaya, S. V.; Osipov, A. V.; Istratov, A. V.; Vartanyan, T. A.; Itina, T. E.

    2016-08-01

    In this work the results of a bimetallic Au-Ag structure deposition from the colloidal system by nanosecond laser radiation are presented. The formation of the extended arrays of gold and silver nanoparticles with controlled morphology is examined. We report the results of formation bimetallic islands films with various electrical and optical properties. The changes in the optical properties of the obtained thin films are found to depend on their morphology.

  15. Physical Vapor Deposition of Thin Films

    Science.gov (United States)

    Mahan, John E.

    2000-01-01

    A unified treatment of the theories, data, and technologies underlying physical vapor deposition methods With electronic, optical, and magnetic coating technologies increasingly dominating manufacturing in the high-tech industries, there is a growing need for expertise in physical vapor deposition of thin films. This important new work provides researchers and engineers in this field with the information they need to tackle thin film processes in the real world. Presenting a cohesive, thoroughly developed treatment of both fundamental and applied topics, Physical Vapor Deposition of Thin Films incorporates many critical results from across the literature as it imparts a working knowledge of a variety of present-day techniques. Numerous worked examples, extensive references, and more than 100 illustrations and photographs accompany coverage of: * Thermal evaporation, sputtering, and pulsed laser deposition techniques * Key theories and phenomena, including the kinetic theory of gases, adsorption and condensation, high-vacuum pumping dynamics, and sputtering discharges * Trends in sputter yield data and a new simplified collisional model of sputter yield for pure element targets * Quantitative models for film deposition rate, thickness profiles, and thermalization of the sputtered beam

  16. Flexible photodiodes constructed with CdTe nanoparticle thin films and single ZnO nanowires on plastics.

    Science.gov (United States)

    Kwak, Kiyeol; Cho, Kyoungah; Kim, Sangsig

    2011-10-14

    We construct a flexible pn heterostructured photodiode using a CdTe nanoparticle thin film and a single ZnO nanowire (NW) on a plastic substrate. The photocurrent characteristics of the flexible photodiode are examined under illumination with 325 nm wavelength light and the photocurrent efficiencies at bias voltages of ± 2.5 V are estimated to be 8.0 and 2.1 µA W(-1) under forward and reverse bias conditions, respectively. The photocurrent generation of the pn heterostructured photodiode is dominantly associated with the transport of the photogenerated charge carriers in the single ZnO NW. Furthermore, the operations of our flexible photodiode are investigated in the upwardly and downwardly bent states, as well as in the flat state.

  17. Deposition of biopolymer films on micromechanical sensors

    DEFF Research Database (Denmark)

    Keller, Stephan Sylvest; Gammelgaard, Lene; Jensen, Marie P.

    2011-01-01

    The influence of various parameters on the spray-coating of thin films of poly(l-lactide) (PLLA) was investigated. The optimized processing conditions were used for deposition of the biodegradable polymer on arrays of SU-8 microcantilevers. The resonance frequency of the cantilevers before and af...

  18. Pulsed laser deposition of nanostructured Ag films

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, Tony [School of Physics, Trinity College, Dublin 2 (Ireland); Doggett, Brendan [School of Physics, Trinity College, Dublin 2 (Ireland); Lunney, James G. [School of Physics, Trinity College, Dublin 2 (Ireland)]. E-mail: jlunney@tcd.ie

    2006-04-30

    Ultra-thin (0.5-5 nm) films of Ag have been prepared by pulsed laser deposition in vacuum using a 26 ns KrF excimer laser at 1 J cm{sup -2}. The deposition was controlled using a Langmuir ion probe and a quartz crystal thickness monitor. Transmission electron microscopy showed that the films are not continuous, but are structured on nanometer size scales. Optical absorption spectra showed the expected surface plasmon resonance feature, which shifted to longer wavelength and increased in strength as the equivalent film thickness was increased. It is shown that Maxwell Garnett effective medium theory can be used to calculate the main features of optical absorption spectra.

  19. Effect of In Situ Thermal Annealing Process on Structural, Optical and Electrical Properties of CdSCdTe Thin-Film Solar Cells Fabricated by Pulsed Laser Deposition

    Science.gov (United States)

    Al-mebir, Alaa Ayad Khedhair

    Cadmium Telluride has long been recognized as the second lowest- cost material after Si in the world photovoltaic market, specifically for thin-film solar cells. The two attractive properties of the CdTe are its nearly ideal band gap of ˜1.5 eV for single p-n junction photovoltaic and its high optical absorption coefficient up to 105 cm-1. Therefore, a thickness of ˜1 mum of CdTe can absorb up to 90% of the incident light. The key to high-performance thin film CdTe-based solar cells is controlling microstructure of the CdS/CdTe through obtaining high-quality crystalline CdTe thin films that have low density pinholes and other defects and form high-quality p-n heterojunction interfaces on the CdS or other window layers. Considering these, the relative high temperatures used for CdTe thick film growth may not be suitable in the thin film case due to lack of control in CdTe microstructure evolution. Therefore, development of low-temperature processes for CdTe thin film solar cells is important to achieving a precise control of the CdS/CdTe microstructure and optoelectronic properties. In addition, low temperatures provide benefits in wider selection of substrates especially those for low-cost, flexible solar cells applications. However, the CdS/CdTe solar cells based on thin CdTe films fabricated at low temperature have generally poor performance as a result of increased density of grain boundaries and defects. In order to address this issue, we have developed an in situ thermal annealing process (iTAP) immediately after the CdS/CdTe deposition using Pulsed laser deposition (PLD) at 200 °C and before the common ex situ CdCl2 annealing typically employed for optimization of the CdTe-based solar cells. A systematic study on the microstructure, optical and optoelectronic properties of CdS/CdTe solar cells processed under different iTAP conditions has been carried out. It has been found that these physical properties depend sensitively on the iTAP processing conditions

  20. Grain boundaries in CdTe thin film solar cells: a review

    Science.gov (United States)

    Major, Jonathan D.

    2016-09-01

    The current state of knowledge on the impact of grain boundaries in CdTe solar cells is reviewed with emphasis being placed on working cell structures. The role of the chemical composition of grain boundaries as well as growth processes are discussed, along with characterisation techniques such as electron beam induced current and cathodoluminescence, which are capable of extracting information on a level of resolution comparable to the size of the grain boundaries. Work which attempts to relate grain boundaries to device efficiency is also assessed and gaps in the current knowledge are highlighted.

  1. Oxygen Incorporation During Fabrication of Substrate CdTe Photovoltaic Devices: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Duenow, J. N.; Dhere, R. G.; Kuciauskas, D.; Li, J. V.; Pankow, J. W.; DeHart, C. M.; Gessert, T. A.

    2012-06-01

    Recently, CdTe photovoltaic (PV) devices fabricated in the nonstandard substrate configuration have attracted increasing interest because of their potential compatibility with flexible substrates such as metal foils and polymer films. This compatibility could lead to the suitability of CdTe for roll-to-roll processing and building-integrated PV. Currently, however, the efficiencies of substrate CdTe devices reported in the literature are significantly lower ({approx}6%-8%) than those of high-performance superstrate devices ({approx}17%) because of significantly lower open-circuit voltage (Voc) and fill factor (FF). In our recent device development efforts, we have found that processing parameters required to fabricate high-efficiency substrate CdTe PV devices differ from those necessary for traditional superstrate CdTe devices. Here, we investigate how oxygen incorporation in the CdTe deposition, CdCl2 heat treatment, CdS deposition, and post-deposition heat treatment affect device characteristics through their effects on the junction. By adjusting whether oxygen is incorporated during these processing steps, we have achieved Voc values greater than 860 mV and efficiencies greater than 10%.

  2. Potentiostatic Deposition and Characterization of Cuprous Oxide Thin Films

    OpenAIRE

    2013-01-01

    Electrodeposition technique was employed to deposit cuprous oxide Cu2O thin films. In this work, Cu2O thin films have been grown on fluorine doped tin oxide (FTO) transparent conducting glass as a substrate by potentiostatic deposition of cupric acetate. The effect of deposition time on the morphologies, crystalline, and optical quality of Cu2O thin films was investigated.

  3. Effect of Annealing on the Properties of Antimony Telluride Thin Films and Their Applications in CdTe Solar Cells

    OpenAIRE

    Zhouling Wang; Yu Hu; Wei Li; Guanggen Zeng; Lianghuan Feng; Jingquan Zhang; Lili Wu; Jingjing Gao

    2014-01-01

    Antimony telluride alloy thin films were deposited at room temperature by using the vacuum coevaporation method. The films were annealed at different temperatures in N2 ambient, and then the compositional, structural, and electrical properties of antimony telluride thin films were characterized by X-ray fluorescence, X-ray diffraction, differential thermal analysis, and Hall measurements. The results indicate that single phase antimony telluride existed when the annealing temperature was high...

  4. Silicon carbide and other films and method of deposition

    Science.gov (United States)

    Mehregany, Mehran (Inventor); Zorman, Christian A. (Inventor); Fu, Xiao-An (Inventor); Dunning, Jeremy (Inventor)

    2011-01-01

    A method of depositing a ceramic film, particularly a silicon carbide film, on a substrate is disclosed in which the residual stress, residual stress gradient, and resistivity are controlled. Also disclosed are substrates having a deposited film with these controlled properties and devices, particularly MEMS and NEMS devices, having substrates with films having these properties.

  5. VUV-light-induced deposited silica films

    Science.gov (United States)

    Buck, Christopher K.; Pedraza, Anthony J.; Benson, Roberto S.; Park, Jae-Won

    1998-05-01

    A novel technique to deposit dielectric films at room temperature is described. The deposition of the silica takes place inside a cylindrical glass chamber where a silent discharge is generated between two electrodes connected to a high voltage, high frequency AC source. The chamber contains two parallel glass tubes where the electrodes are located and is filled with argon or xenon at a pressure of 100 mbar. Under these conditions, it has been shown that high intensity VUV light is generated peaking at 126 nm for argon and at 172 nm for xenon. This VUV radiation seems to produce photoablation of the glass tubes that surround the electrodes. Upon operation of the lamp, polyimide, polypropylene and silicon wafer substrates lying at the bottom of the vessel became coated with silica. The films, identified using X-ray photoelectron spectroscopy (XPS), revealed that the silica is oxygen-deficient with a composition of SiO x where x is between 1.7 and 1.8. The deposition rate on silicon wafers was measured by ellipsometry. When Xe gas is used the deposition rate is much lower than when Ar is used. This result is consistent with a photoablation process since the energy of the photons generated in Ar peaks at 10 eV while those generated in Xe peaks at 7 eV. These energy values should be compared with the O-Si bond strength energy that is 8.3 eV. The morphology and structure of the films were examined by scanning and transmission electron microscopies. Deposition of carbonaceous films occurred when the glass tubes containing the electrodes were coated with carbon.

  6. Pulsed laser deposition of ferroelectric thin films

    Science.gov (United States)

    Sengupta, Somnath; McKnight, Steven H.; Sengupta, Louise C.

    1997-05-01

    It has been shown that in bulk ceramic form, the barium to strontium ratio in barium strontium titanium oxide (Ba1- xSrxTiO3, BSTO) affects the voltage tunability and electronic dissipation factor in an inverse fashion; increasing the strontium content reduces the dissipation factor at the expense of lower voltage tunability. However, the oxide composites of BSTO developed at the Army Research Laboratory still maintain low electronic loss factors for all compositions examined. The intent of this study is to determine whether such effects can be observed in the thin film form of the oxide composites. The pulsed laser deposition (PLD) method has been used to deposit the thin films. The different compositions of the compound (with 1 wt% of the oxide additive) chosen were: Ba0.3Sr0.7TiO3, Ba0.4Sr0.6TiO3, Ba0.5Sr0.5TiO3, Ba0.6Sr0.4TiO3, and Ba0.7Sr0.3TiO3. The electronic properties investigated in this study were the dielectric constant and the voltage tunability. The morphology of the thin films were examined using the atomic force microscopy. Fourier transform Raman spectroscopy was also utilized for optical characterization of the thin films. The electronic and optical properties of the thin films and the bulk ceramics were compared. The results of these investigations are discussed.

  7. Growth of CdTe on Si(100) surface by ionized cluster beam technique: Experimental and molecular dynamics simulation

    Science.gov (United States)

    Araghi, Houshang; Zabihi, Zabiholah; Nayebi, Payman; Ehsani, Mohammad Mahdi

    2016-10-01

    II-VI semiconductor CdTe was grown on the Si(100) substrate surface by the ionized cluster beam (ICB) technique. In the ICB method, when vapors of solid materials such as CdTe were ejected through a nozzle of a heated crucible into a vacuum region, nanoclusters were created by an adiabatic expansion phenomenon. The clusters thus obtained were partially ionized by electron bombardment and then accelerated onto the silicon substrate at 473 K by high potentials. The cluster size was determined using a retarding field energy analyzer. The results of X-ray diffraction measurements indicate the cubic zinc blende (ZB) crystalline structure of the CdTe thin film on the silicon substrate. The CdTe thin film prepared by the ICB method had high crystalline quality. The microscopic processes involved in the ICB deposition technique, such as impact and coalescence processes, have been studied in detail by molecular dynamics (MD) simulation.

  8. Deposition and characterization of CuInS2 thin films deposited over copper thin films

    Science.gov (United States)

    Thomas, Titu; Kumar, K. Rajeev; Kartha, C. Sudha; Vijayakumar, K. P.

    2015-06-01

    Simple, cost effective and versatile spray pyrolysis method is effectively combined with vacuum evaporation for the deposition of CuIns2 thin films for photovoltaic applications. In the present study In2s3 was spray deposited over vacuum evaporated Cu thin films and Cu was allowed to diffuse in to the In2S3 layer to form CuInS2. To analyse the dependence of precursor volume on the formation of CuInS2 films structural, electrical and morphological analzes are carried out. Successful deposition of CuInS2thin films with good crystallinity and morphology with considerably low resistivity is reported in this paper.

  9. Electrical Properties Analysis of Copper doped CdTe/CdS Deposited Thin Films on ITO Coated Glass Substrates

    Science.gov (United States)

    Lesinski, Darren; Flaherty, James; Sahiner, M. Alper

    CdTe proves to be a viable source for renewable energy in the form of photovoltaic conversion. While CdTe/CdS naturally provide interesting results adding dopants to the cell can yield higher conversion efficiencies. Copper, famous for its electrical properties, can be used as a dopant in the CdTe layer. In conjunction with its dopant characteristics Copper also improves cell performance by acting as a low resistant and high current back contact. All thin films were synthesized using pulsed laser deposition onto ITO coated glass substrates. The CdS layer across all cells has an approximate thickness of 1500 Angstroms. The following CdTe layer has an approximate thickness of 5500 Angstroms. This created the base cell that was then doped. Cu, typically deposited using sublimation or vapor deposition, was done by PLD as well. Two of the three base cells were treated with Cu using the same deposition parameters. The third cell also received a CdCl treatment on top of the Cu layer to understand the effect when the oxygen layer is deferred. Ellipsometer measurements were used to confirm layer thickness. XRD analysis was used to confirm the presence of Cu and the crystal structure of the thin films. A Hall Effect Measurement system was used to measure active charge carrier concentration introduced by dopant. Also, a Keithley sourcemeter was utilized to determine photovoltaic properties. Notable results discussed will be the effects of Copper dopant on the electrical properties of CdS/CdTe based solar cells.

  10. Optical characterization of epitaxial single crystal CdTe thin films on Al{sub 2}O{sub 3} (0001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Jovanovic, S.M.; Devenyi, G.A., E-mail: devenyga@mcmaster.ca; Jarvis, V.M.; Meinander, K.; Haapamaki, C.M.; Kuyanov, P.; Gerber, M.; LaPierre, R.R.; Preston, J.S.

    2014-11-03

    The optoelectronic properties of single crystal CdTe thin films were investigated by photoluminescence spectroscopy, photoreflectance spectroscopy and variable angle spectroscopic ellipsometry. The room temperature bandgap was measured to be 1.51 eV and was consistent between spectroscopic measurements and previously reported values. Breadth of bandgap emission was consistent with high quality material. Low temperature photoluminescence spectra indicated a dominant emission consistent with bound excitons. Emissions corresponding to self-compensation defects, doping and contaminants were not found. Variable angle spectroscopic ellipsometry measurements over the near-UV to infrared range demonstrated sharp resonance peaks. All spectroscopic measurements indicate high quality thin film material of comparable or better quality than bulk CdTe. - Highlights: • High quality epitaxial CdTe thin films were grown. • Two dimensional X-ray diffraction characterization confirmed single crystal material. • Photoluminescence indicated low defect density when compared to bulk single crystals. • Optical characterization indicated the presence of room temperature excitons.

  11. Effect of ZnTe and CdZnTe Alloys at the Back Contact of 1-μm-Thick CdTe Thin Film Solar Cells

    Science.gov (United States)

    Amin, Nowshad; Yamada, Akira; Konagai, Makoto

    2002-05-01

    N2-doped ZnTe was introduced onto 1-μm-thick CdTe absorbers in order to reduce the carrier recombination at the back contact of CdS/CdTe/C/Ag configuration solar cells. ZnTe films were grown by molecular beam epitaxy (MBE) on GaAs and Corning glass substrates to investigate the characteristics of the films. Epitaxial growth of ZnTe was realized on GaAs substrates and a hole concentration of 8 × 1018 cm-3 with a resistivity of 0.045 Ω \\cdotcm was achieved as a result of nitrogen doping. In contrast, polycrystalline ZnTe films were grown on Corning glass and CdTe thin films. Dark and photoconductivity of ZnTe films increased to 1.43 × 10-5 S/cm and 1.41 × 10-4 S/cm, respectively, while the Zn to Te ratio was decreased to 0.25 during MBE growth. These ZnTe films with different thicknesses were inserted into close-spaced sublimation (CSS)-grown 1-μm-thick CdTe solar cells. A conversion efficiency of 8.31% (Voc: 0.74 V, Jsc: 22.98 mA/cm2, FF: 0.49, area: 0.5 cm2) was achieved for a 0.2-μm-thick ZnTe layer with a cell configuration of CdS/CdTe/ZnTe/Cu-doped-C/Ag. Furthermore, to overcome the problem of possible recombination loss in the interface layer of CdTe and ZnTe, the intermediate ternary CdZnTe is investigated. The compositional factor in Cd1-xZnxTe:N alloy is varied and the dependence of the conductivity is evaluated. For instance, Cd0.5Zn0.5Te:N, with dark and photoconductivity of 2.13 × 10-6 and 2.9 × 10-5 S/cm, respectively, is inserted at the back contact of a 1-μm-thick CdTe solar cell. A conversion efficiency of 7.46% (Voc: 0.68 V, Jsc: 22.60 mA/cm2, FF: 0.49, area: 0.086 cm2) was achieved as the primary result for a 0.2-μm-thick Cd0.5Zn0.5Te:N layer with the cell configuration of CdS/CdTe/Cd0.5Zn0.5Te:N/Au.

  12. Multilayered films incorporating CdTe quantum dots with tunable optical properties for antibacterial application

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xuelian [Institute for Clean Energy and Advanced Materials, Southwest University, 1 Tiansheng Road, Chongqing 400715 (China); School of Chemistry and Chemical Engineering, Southwest University, 1 Tiansheng Road, Chongqing 400715 (China); Lu, Zhisong, E-mail: zslu@swu.edu.cn [Institute for Clean Energy and Advanced Materials, Southwest University, 1 Tiansheng Road, Chongqing 400715 (China); Li, Qing, E-mail: qli@swu.edu.cn [School of Chemistry and Chemical Engineering, Southwest University, 1 Tiansheng Road, Chongqing 400715 (China); School of Materials Science and Engineering, Southwest University, 1 Tiansheng Road, Chongqing 400715 (China)

    2013-12-02

    Tunable absorption/emission and antibacterial activity are highly desirable for antibacterial decorative coating layers. In this study, films with both tunable optical and effective antibacterial properties were fabricated with cadmium telluride quantum dots (QDs) and poly-L-lysine (PLL) via layer-by-layer assembly. Absorption and photoluminescence spectra as well as surface morphology were examined to monitor the film growth. The films are fabricated in a logarithmic growth mode, exhibiting effective antibacterial activity against Escherichia coli and good biocompatibility to Hela cells. By changing sizes of the incorporated QDs, optical properties of the films can be easily tailored. The PLL/QDs' multilayered films may be used as colorful coating layers for applications requiring both unique optical and antibacterial properties. - Highlights: • A layer-by-layer film incorporating quantum dots and poly-L-lysine was fabricated. • The film shows tunable optical properties and antibacterial activity. • The film is built up in a logarithmic growth mode.

  13. Preparation of p-type NiO films by reactive sputtering and their application to CdTe solar cells

    Science.gov (United States)

    Ishikawa, Ryousuke; Furuya, Yasuaki; Araki, Ryouichi; Nomoto, Takahiro; Ogawa, Yohei; Hosono, Aikyo; Okamoto, Tamotsu; Tsuboi, Nozomu

    2016-02-01

    Transparent p-type NiO films were prepared by reactive sputtering using the facing-target system under Ar-diluted O2 gas at Tsub of 30 and 200 °C. The increasing intensity of dominant X-ray diffraction (XRD) peaks indicates improvements in the crystallinity of NiO films upon Cu doping. In spite of the crystallographic and optical changes after Cu-doping, the electrical properties of Cu-doped NiO films were slightly improved. Upon Ag-doping at 30 °C under low O2 concentration, on the other hand, the intensity of the dominant (111) XRD peaks was suppressed and p-type conductivity increased from ˜10-3 to ˜10-1 S cm-1. Finally, our Ag-doped NiO films were applied as the back contact of CdTe solar cells. CdTe solar cells with a glass/ITO/CdS/CdTe/NiO structure exhibited an efficiency of 6.4%, suggesting the high potential of using p-type NiO for the back-contact film in thin-film solar cells.

  14. The effects of high temperature processing on the structural and optical properties of oxygenated CdS window layers in CdTe solar cells

    Science.gov (United States)

    Paudel, Naba R.; Grice, Corey R.; Xiao, Chuanxiao; Yan, Yanfa

    2014-07-01

    High efficiency CdTe solar cells typically use oxygenated CdS (CdS:O) window layers. We synthesize CdS:O window layers at room temperature (RT) and 270 °C using reactive sputtering. The band gaps of CdS:O layers deposited at RT increase when O2/(O2 + Ar) ratios in the deposition chamber increase. On the other hand, the band gaps of CdS:O layers deposited at 270 °C decrease as the O2/(O2 + Ar) ratios increase. Interestingly, however, our high temperature closed-space sublimation (CSS) processed CdTe solar cells using CdS:O window layers deposited at RT and 270 °C exhibit very similar cell performance, including similar short-circuit current densities. To understand the underlying reasons, CdS:O thin films deposited at RT and 270 °C are annealed at temperatures that simulate the CSS process of CdTe deposition. X-ray diffraction, atomic force microscopy, and UV-visible light absorption spectroscopy characterization of the annealed films reveals that the CdS:O films deposited at RT undergo grain regrowth and/or crystallization and exhibit reduced band gaps after the annealing. Our results suggest that CdS:O thin films deposited at RT and 270 °C should exhibit similar optical properties after the deposition of CdTe layers, explaining the similar cell performance.

  15. 具有复合背接触层的 CdTe多晶薄膜太阳电池%Polycrystalline CdTe thin- film solar cells with complex back contact layers

    Institute of Scientific and Technical Information of China (English)

    覃文治; 夏庚培; 郑家贵; 李卫; 蔡伟; 冯良桓; 蔡亚平; 黎兵; 张静全; 武莉莉

    2005-01-01

    To improve the properties of back contacts of CdTe solar cells, ZnTe:Cu and polycrystalline Cd1- xZnxTe films were deposited by simultaneous evaporation. Investigative data of the configuration and performance indicate that energy gap of Cd1- xZnxTe films assume quadratic connection with zinc content. With increasing of Cu content, energy gap of polycrystalline ZnTe:Cu will decrease. ZnTe/ZnTe:Cu or Cd1- xZnxTe/ZnTe:Cu back contacted cells can reduce the heterogeneous interface state density and modify the structure of energy band of the solar cells. Furthermore, diffusion of Cu can avoid by this compound films in CdTe solar cells. An efficiency of 13.38% of solar cell with dimension of 0.502cm2was fabricated.%为了提高 CdTe太阳电池的背接触性能,用共蒸发法制备了 ZnTe:Cu和 Cd1- xZnxTe多晶薄膜. 研究结果表明: Cd1- xZnxTe多晶薄膜的能隙与锌含量呈二次方关系, ZnTe:Cu多晶薄膜能隙随着掺 Cu浓度的增加而减小.分别用 ZnTe/ZnTe:Cu和 Cd1- xZnxTe/ZnTe:Cu复合膜作为背接触层,既能 修饰异质结界面,改善电池的能带结构,又能防止 Cu原子向电池内部扩散.因此获得了面积 0.502cm2,转换效率为 13.38%的 CdTe多晶薄膜太阳电池.

  16. Stress in and texture of PVD deposited metal nitride films

    NARCIS (Netherlands)

    Machunze, R.

    2010-01-01

    Thin metal nitride films deposited by Physical Vapor Deposition (PVD) are used amongst many other applications as wear protective coatings in tool industry or as diffusion barriers in integrated circuit technology. Typically these films exhibit a residual in-plane stress when deposited onto rigid su

  17. Strontium-Doped Lanthanum Manganite Films Prepared by Magnetic Deposition

    DEFF Research Database (Denmark)

    Menon, Mohan; Larsen, Casper; Andersen, Kjeld Bøhm

    2009-01-01

    Deposition of La0.85Sr0.15MnO3 (LSM) films from suspensions using a magnetic field was found to be a cheap and quick technique. Ninety weight percent of the particles present in the suspensions were deposited within the first minute of the deposition, and the thickness of the film varied linearly...

  18. Cadmium sulfide thin films deposited by close spaced sublimation and cadmium sulfide/cadmium telluride solar cells

    Science.gov (United States)

    Marinskiy, Dmitriy Nikolaevich

    1998-12-01

    One of the applications of CdS films is as a window layer in CdTe and Cu(In,Ga)Sesb2 solar cells. The study of the optical and structural properties of CdS films deposited by close spaced sublimation as well as their influence on CdS/CdTe solar cell performance is part of the CdTe solar cell program at the University of South Florida. CdS films have been deposited by the close-spaced sublimation technique. The influence of the main process parameters, the substrate and source temperatures, and the ambient in the deposition chamber has been investigated. As-deposited films have been subjected to heat treatments in Hsb2 ambient, in CdClsb2 atmosphere, and in atmosphere with small amounts of oxygen. A special annealing chamber was built to carry out the annealing experiments in the presence of CdClsb2 vapor and oxygen. Several CSS chambers were assembled to study the influence of various process parameters simultaneously and validate the results. Results of scanning electron microscopy and photoluminescence measurements have been used as the primary characterization techniques. X-ray diffraction, electron microprobe analysis, and transmission measurements have also been carried out. It was found that as deposited CdS films have a hexagonal structure independent of the process parameters used. The presence of a CdO phase was detected in the samples grown with the highest oxygen concentration in the ambient. The resistivity of CdS films is controlled by intergrain barriers. Photoluminescence measurements showed the presence of oxygen-acceptor transition and a wide variation in the intensity of deep emission bands. The variation in the intensities was correlated with the variation in the deposition and annealing conditions. However, no correlation was found between the PL intensities of defect bands and cell performance. CdS/CdTe junctions have been fabricated using standard deposition and postgrowth techniques developed in the USF solar cells laboratory. All cells have

  19. Manufacturing of CSS CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, D. [ANTEC Solar GmbH, Rudisleben (Germany)

    2000-02-21

    Due to its basic physical and chemical properties CdTe has become a favoured base material for thin film solar cells, using robust, high-throughput manufacturing procedures. The technology shows significant potential for attaining cost levels of <0.5 Euro/W{sub p}. Close-spaced sublimation (CSS) is the fastest and simplest deposition process for both semiconductors used, CdTe and CdS, permitting in-line production at a high linear speed of about 1 m/min. The individual manufacturing steps for integrated modules are explained in view of their incorporation into the production line. ANTEC solar GmbH is engaged to enter the production of CdTe thin film modules on a scale of 10 MW{sub p} (100000 m{sup 2}) per annum, using CSS as the deposition procedure for the semiconductor films, and high-rate in-line sputtering for transparent and opaque contacts. Standard module size will be 60 x 120 cm{sup 2}. The production line is presently under construction. (orig.)

  20. Effect of In Situ Thermal Annealing on Structural, Optical, and Electrical Properties of CdS/CdTe Thin Film Solar Cells Fabricated by Pulsed Laser Deposition

    OpenAIRE

    Alaa Ayad Al-mebir; Paul Harrison; Ali Kadhim; Guanggen Zeng; Judy Wu

    2016-01-01

    An in situ thermal annealing process (iTAP) has been introduced before the common ex situ cadmium chloride (CdCl2) annealing to improve crystal quality and morphology of the CdTe thin films after pulsed laser deposition of CdS/CdTe heterostructures. A strong correlation between the two annealing processes was observed, leading to a profound effect on the performance of CdS/CdTe thin film solar cells. Atomic force microscopy and Raman spectroscopy show that the iTAP in the optimal processing w...

  1. Photoluminescence study of Cu diffusion in CdTe

    Energy Technology Data Exchange (ETDEWEB)

    Grecu, D.; Compaan, A.D. [Department of Physics, University of Toledo, Toledo, Ohio (United States)

    1999-03-01

    We report changes in the photoluminescence spectra associated with the diffusion of Cu in CdTe thin films used in CdTe/CdS solar cells. Films grown by vapor transport deposition and radio-frequency sputtering as well as single crystal CdTe were included in the study. The main effects of Cu diffusion appear to be the quenching of a donor-acceptor transition associated with Cd vacancies and the increase in intensity of a lower energy broad-band transition. The PL is subsequently used to explore the effects of electric fields on Cu diffusion. The role of Te as a diffusion barrier for Cu is investigated. {copyright} {ital 1999 American Institute of Physics.}

  2. Optical Parameters of Spray-Deposited CdS1-y Te y Thin Films

    Science.gov (United States)

    Ikhmayies, Shadia J.

    2016-11-01

    CdS x Te1-x and CdS1-y Te y solid solutions are usually formed in the interfacial region in CdS/CdTe solar cells during the deposition of the CdTe layer and/or the processing steps of the device. In this work, indium-doped CdS1-y Te y thin films were prepared by first producing CdS:In thin films by the spray pyrolysis technique on glass substrates, then annealing the films in nitrogen atmosphere in the presence of elemental tellurium. The films were characterized by scanning electron microscopy, energy dispersive x-ray spectroscopy, and transmittance measurements. The transmittance was used to deduce the reflectance from which the optical parameters were computed. The extinction coefficient, refractive index, the real and imaginary parts of the dielectric constant, optical conductivity, and energy loss were computed, and their dependence on the composition was investigated. In addition, the dispersion of the refractive index was analyzed by the single oscillator model, and dispersion parameters were investigated.

  3. Optical Parameters of Spray-Deposited CdS1- y Te y Thin Films

    Science.gov (United States)

    Ikhmayies, Shadia J.

    2017-02-01

    CdS x Te1- x and CdS1- y Te y solid solutions are usually formed in the interfacial region in CdS/CdTe solar cells during the deposition of the CdTe layer and/or the processing steps of the device. In this work, indium-doped CdS1- y Te y thin films were prepared by first producing CdS:In thin films by the spray pyrolysis technique on glass substrates, then annealing the films in nitrogen atmosphere in the presence of elemental tellurium. The films were characterized by scanning electron microscopy, energy dispersive x-ray spectroscopy, and transmittance measurements. The transmittance was used to deduce the reflectance from which the optical parameters were computed. The extinction coefficient, refractive index, the real and imaginary parts of the dielectric constant, optical conductivity, and energy loss were computed, and their dependence on the composition was investigated. In addition, the dispersion of the refractive index was analyzed by the single oscillator model, and dispersion parameters were investigated.

  4. Direct observation of electrical properties of grain boundaries in sputter-deposited CdTe using scan-probe microwave reflectivity based capacitance measurements

    Science.gov (United States)

    Tuteja, Mohit; Koirala, Prakash; MacLaren, Scott; Collins, Robert; Rockett, Angus

    2015-10-01

    Polycrystalline CdTe in 12% efficient solar cells has been studied using scanning microwave impedance microscopy (sMIM). The CdS/CdTe junctions were grown on transparent-conducting-oxide-coated soda lime glass using rf sputter deposition. sMIM based capacitance measurements were performed on the exposed surface of CdCl2 treated CdTe adjacent to thermal-evaporation-deposited Cu/Au back contacts. The sMIM instrument was operated at ˜3 GHz, and capacitance measurements were performed as a function of ac and dc voltage biases applied to the tip, with and without sample illumination. Although dc capacitance measurements are affected by sample topography, the differential capacitance measurement was shown to be topography independent. It was found that the grain boundaries exhibit a depleted carrier concentration as compared to the grain bulk. This depletion effect is enhanced under photo-generated carrier separation or under sufficiently large probe tip biases opposite to the majority carrier charge.

  5. Pulsed laser deposition and characterization of Alnico5 magnetic films

    Energy Technology Data Exchange (ETDEWEB)

    Butt, M.Z., E-mail: mzbutt49@yahoo.com [Department of Physics, GC University, Lahore 54000 (Pakistan); Ali, Dilawar [Department of Physics, GC University, Lahore 54000 (Pakistan); Ahmad, Fayyaz [Department of Physics, University of Engineering and Technology, Lahore 54890 (Pakistan); Magnetophotonics Research Laboratory, Department of Physics, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2013-09-01

    Alnico5 films were deposited by pulsed laser deposition on glass substrate at room temperature under a vacuum ∼10{sup −3} Torr in the absence and in the presence of 500 Oe external transverse magnetic field applied on the plasma plume during film deposition. For this purpose, Nd:YAG laser was employed to ablate the Alnico5 target. The ablated material was deposited on glass substrate placed at a distance of 2 cm from the target. The structural and magnetic properties of the film were analyzed by X-ray diffraction, atomic force microscope, and vibrating sample magnetometer. X-ray diffraction patterns showed that the Alnico5 films were amorphous in nature. Atomic force microscopy revealed that the Alnico5 film deposited in absence of external magnetic field has larger root-mean-square roughness value (60.2 nm) than the magnetically deposited film (42.9 nm). Vibrating sample magnetometer measurements showed that the in-plane saturation magnetization of Alnico5 film deposited in the presence of external magnetic field increases by 32% as compared to that for the film deposited in the absence of external magnetic field. However, the out-of-plane saturation magnetization was almost independent of the external magnetic field. In magnetically deposited film, there is in-plane anisotropy parallel to the applied external magnetic field.

  6. The mechanical properties of thin alumina film deposited by metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Gellings, P.J.; Vendel, van de D.; Metselaar, H.S.C.; Corbach, van H.D.; Fransen, T.

    1995-01-01

    Amorphous alumina films were deposited by metal-organic chemical vapour deposition (MOCVD) on stainless steel, type AISI 304. The MOCVD experiments were performed in nitrogen at low and atmospheric pressures. The effects of deposition temperature, growth rate and film thickness on the mechanical pro

  7. Deposition of Aluminium Oxide Films by Pulsed Reactive Sputtering

    Institute of Scientific and Technical Information of China (English)

    Xinhui MAO; Bingchu CAI; Maosong WU; Guoping CHEN

    2003-01-01

    Pulsed reactive sputtering is a novel process used to deposit some compound films, which are not deposited by traditional D.C. reactive sputtering easily. In this paper some experimental results about the deposition of Al oxide films by pulsed reactive sputtering are presented. The hysteresis phenomenon of the sputtering voltage and deposition rate with the change of oxygen flow during sputtering process are discussed.

  8. Correlations of Capacitance-Voltage Hysteresis with Thin-Film CdTe Solar Cell Performance During Accelerated Lifetime Testing

    Energy Technology Data Exchange (ETDEWEB)

    Albin, D.; del Cueto, J.

    2011-03-01

    In this paper we present the correlation of CdTe solar cell performance with capacitance-voltage hysteresis, defined presently as the difference in capacitance measured at zero-volt bias when collecting such data with different pre-measurement bias conditions. These correlations were obtained on CdTe cells stressed under conditions of 1-sun illumination, open-circuit bias, and an acceleration temperature of approximately 100 degrees C.

  9. Room-Temperature Deposition of NbN Superconducting Films

    Science.gov (United States)

    Thakoor, S.; Lamb, J. L.; Thakoor, A. P.; Khanna, S. K.

    1986-01-01

    Films with high superconducting transition temperatures deposited by reactive magnetron sputtering. Since deposition process does not involve significantly high substrate temperatures, employed to deposit counter electrode in superconductor/insulator/superconductor junction without causing any thermal or mechanical degradation of underlying delicate tunneling barrier. Substrates for room-temperature deposition of NbN polymeric or coated with photoresist, making films accessible to conventional lithographic patterning techniques. Further refinements in deposition technique yield films with smaller transition widths, Tc of which might approach predicted value of 18 K.

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

    Energy Technology Data Exchange (ETDEWEB)

    Henley, W.B.; Sacks, G.J. [Univ. of South Florida, Tampa, FL (United States). Center of Microelectronics

    1997-03-01

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

  11. Characterization of Cu1.4Te Thin Films for CdTe Solar Cells

    Directory of Open Access Journals (Sweden)

    Guangcan Luo

    2014-01-01

    Full Text Available The copper telluride thin films were prepared by a coevaporation technique. The single-phase Cu1.4Te thin films could be obtained after annealing, and annealing temperature higher than 220°C could induce the presence of cuprous telluride coexisting phase. Cu1.4Te thin films also demonstrate the high carrier concentration and high reflectance for potential photovoltaic applications from the UV-visible-IR transmittance and reflectance spectra, and Hall measurements. With contacts such as Cu1.4Te and Cu1.4Te/CuTe, cell efficiencies comparable to those with conventional back contacts have been achieved. Temperature cycle tests show that the Cu1.4Te contact buffer has also improved cell stability.

  12. Elucidating PID Degradation Mechanisms and In Situ Dark I–V Monitoring for Modeling Degradation Rate in CdTe Thin-Film Modules

    Energy Technology Data Exchange (ETDEWEB)

    Hacke, Peter; Spataru, Sergiu; Johnston, Steve; Terwilliger, Kent; VanSant, Kaitlyn; Kempe, Michael; Wohlgemuth, John; Kurtz, Sarah; Olsson, Anders; Propst, Michelle

    2016-11-01

    A progression of potential-induced degradation (PID) mechanisms are observed in CdTe modules, including shunting/junction degradation and two different manifestations of series resistance depending on the stress level and water ingress. The dark I-V method for in-situ characterization of Pmax based on superposition was adapted for the thin-film modules undergoing PID in view of the degradation mechanisms observed. An exponential model based on module temperature and relative humidity was fit to the PID rate for multiple stress levels in chamber tests and validated by predicting the observed degradation of the module type in the field.

  13. High throughput manufacturing of thin-film CdTe photovoltaic modules. Annual subcontract report, 16 November 1993--15 November 1994

    Energy Technology Data Exchange (ETDEWEB)

    Sandwisch, D W [Solar Cells, Inc., Toledo, OH (United States)

    1995-11-01

    This report describes work performed by Solar Cells, Inc. (SCI), under a 3-year subcontract to advance SCI`s PV manufacturing technologies, reduce module production costs, increase module performance, and provide the groundwork for SCI to expand its commercial production capacities. SCI will meet these objectives in three phases by designing, debugging, and operating a 20-MW/year, automated, continuous PV manufacturing line that produces 60-cm {times} 120-cm thin-film CdTe PV modules. This report describes tasks completed under Phase 1 of the US Department of Energy`s PV Manufacturing Technology program.

  14. Characterization of copper selenide thin films deposited by chemical bath deposition technique

    Science.gov (United States)

    Al-Mamun; Islam, A. B. M. O.

    2004-11-01

    A low-cost chemical bath deposition (CBD) technique has been used for the preparation of Cu2-xSe thin films onto glass substrates and deposited films were characterized by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV-vis spectrophotometry. Good quality thin films of smooth surface of copper selenide thin films were deposited using sodium selenosulfate as a source of selenide ions. The structural and optical behaviour of the films are discussed in the light of the observed data.

  15. Studies of crystalline CdZnTe radiation detectors and polycrystalline thin film CdTe for X-ray imaging applications

    CERN Document Server

    Ede, A

    2001-01-01

    The development of a replacement to the conventional film based X-ray imaging technique is required for many reasons. One possible route for this is the use of a large area film of a suitable semiconductor overlaid on an amorphous silicon readout array. A suitable semiconductor exists in cadmium telluride and its tertiary alloy cadmium zinc telluride. In this thesis the spectroscopic characteristics of commercially available CZT X- and gamma-radiation detectors are established. The electronic, optical, electro-optic, structural and compositional properties of these detectors are then investigated. The attained data is used to infer a greater understanding for the carrier transport in a CZT radiation detector following the interaction of a high energy photon. Following this a method used to fabricate large area films of CdTe on a commercial scale is described. This is cathodic electrodeposition from an aqueous electrolyte. The theory and experimental arrangement for this technique are described in detail with ...

  16. Selective CdTe Nanoheteroepitaxial Growth on Si(100) Substrates Using the Close-Spaced Sublimation Technique Without the Use of a Mask

    Science.gov (United States)

    Diaz, A.; Quinones, S. A.; Ferrer, D. A.

    2013-06-01

    The development of HgCdTe detectors requires high sensitivity, small pixel size, low defect density, long-term thermal-cycling reliability, and large-area substrates. CdTe bulk substrates were initially used for epitaxial growth of HgCdTe films. However, CdTe has a lattice mismatch with long-wavelength infrared (LWIR) and middle-wavelength infrared (MWIR) HgCdTe that results in detrimental dislocation densities above mid-106 cm-2. This work explores the use of CdTe/Si as a possible substrate for HgCdTe detectors. Although there is a 19% lattice mismatch between CdTe and Si, the nanoheteroepitaxy (NHE) technique makes it possible to grow CdTe on Si substrates with fewer defects at the CdTe/Si interface. In this work, Si(100) was patterned using photolithography and dry etching to create 500-nm to 1- μm pillars. CdTe was selectively deposited on the pillar surfaces using the close-spaced sublimation (CSS) technique. Scanning electron microscopy (SEM) was used to characterize the CdTe selective growth and grain morphology, and transmission electron microscopy (TEM) was used to analyze the structure and quality of the grains. CdTe selectivity was achieved for most of the substrate and source temperatures used in this study. The ability to selectively deposit CdTe on patterned Si(100) substrates without the use of a mask or seed layer has not been observed before using the CSS technique. The results from this study confirm that CSS has the potential to be an effective and low-cost technique for selective nanoheteroepitaxial growth of CdTe films on Si(100) substrates for infrared detector applications.

  17. ZnO thin films prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tsoutsouva, M.G. [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780 Athens (Greece); Panagopoulos, C.N., E-mail: chpanag@metal.ntua.gr [Laboratory of Physical Metallurgy, National Technical University of Athens, Zografos, 15780 Athens (Greece); Papadimitriou, D. [National Technical University of Athens, Department of Physics, GR-15780 Athens (Greece); Fasaki, I.; Kompitsas, M. [Theor. and Phys./Chem. Institute, National Hellenic Research Foundation, 48 Vas. Konstantinou Ave., 11635 Athens (Greece)

    2011-04-15

    Zinc oxide (ZnO) thin films were deposited on soda lime glass substrates by pulsed laser deposition (PLD) in an oxygen-reactive atmosphere. The structural, optical, and electrical properties of the as-prepared thin films were studied in dependence of substrate temperature and oxygen pressure. High quality polycrystalline ZnO films with hexagonal wurtzite structure were deposited at substrate temperatures of 100 and 300 deg. C. The RMS roughness of the deposited oxide films was found to be in the range 2-9 nm and was only slightly dependent on substrate temperature and oxygen pressure. Electrical measurements indicated a decrease of film resistivity with the increase of substrate temperature and the decrease of oxygen pressure. The ZnO films exhibited high transmittance of 90% and their energy band gap and thickness were in the range 3.26-3.30 eV and 256-627 nm, respectively.

  18. Ion Beam Assisted Deposition Of Optical Thin Films - Recent Results

    Science.gov (United States)

    McNally, J. J.; Al-Jumaily, G. A.; Wilson, S. R.; McNeil, J. R.

    1985-11-01

    We have examined the properties of dielectric (Ti02, Si02, -Al203, Ta205 and Hf02) films deposited using ion-assisted deposition (IAD). The films were characterized using an angularly resolved scatterometer, spectrophotometer and Raman spectroscopy. A reduction in optical scatter, especially that due to low spatial frequencies, is observed for films deposited with simultaneous ion bombardment. Higher values of refractive index are obtained for films deposited using IAD. Raman spectra indicate a crystalline phase change in TiO2 films is induced by bombardment of samples with 02 ions during deposition. Other experimental data and the effects of the induced phase transition on the optical properties of TiO2 will be discussed.

  19. Influence of deposition time on the properties of chemical bath deposited manganese sulfide thin films

    Directory of Open Access Journals (Sweden)

    Anuar Kassim

    2010-12-01

    Full Text Available Manganese sulfide thin films were chemically deposited from an aqueous solution containing manganese sulfate, sodium thiosulfate and sodium tartrate. The influence of deposition time (2, 3, 6 and 8 days on the properties of thin films was investigated. The structure and surface morphology of the thin films were studied by X-ray diffraction and atomic force microscopy, respectively. In addition, in order to investigate the optical properties of the thin films, the UV-visible spectrophotometry was used. The XRD results indicated that the deposited MnS2 thin films exhibited a polycrystalline cubic structure. The number of MnS2 peaks on the XRD patterns initially increased from three to six peaks and then decreased to five peaks, as the deposition time was increased from 2 to 8 days. From the AFM measurements, the film thickness and surface roughness were found to be dependent on the deposition time.

  20. Long Carrier Lifetimes in Large-Grain Polycrystalline CdTe Without CdCl2

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Soren A.; Burst, James M.; Duenow, Joel N.; Guthrey, Harvey L.; Moseley, John; Moutinho, Helio R.; Johnston, Steve W.; Kanevce, Ana; Al-Jassim, Mowafak M.; Metzger, Wyatt K.

    2016-06-27

    For decades, polycrystalline CdTe thin films for solar applications have been restricted to grain sizes of microns or less whereas other semiconductors such as silicon and perovskites have produced devices with grains ranging from less than a micron to more than 1 mm. Because the lifetimes in as-deposited polycrystalline CdTe films are typically limited to less than a few hundred picoseconds, a CdCl2 treatment is generally used to improve the lifetime; but this treatment may limit the achievable hole density by compensation. Here, we establish methods to produce CdTe films with grain sizes ranging from hundreds of nanometers to several hundred microns by close-spaced sublimation at industrial manufacturing growth rates. Two-photon excitation photoluminescence spectroscopy shows a positive correlation of lifetime with grain size. Large-grain, as-deposited CdTe exhibits lifetimes exceeding 10 ns without Cl, S, O, or Cu. This uncompensated material allows dopants such as P to achieve a hole density of 1016 cm-3, which is an order of magnitude higher than standard CdCl2-treated devices, without compromising the lifetime.

  1. Long carrier lifetimes in large-grain polycrystalline CdTe without CdCl2

    Science.gov (United States)

    Jensen, S. A.; Burst, J. M.; Duenow, J. N.; Guthrey, H. L.; Moseley, J.; Moutinho, H. R.; Johnston, S. W.; Kanevce, A.; Al-Jassim, M. M.; Metzger, W. K.

    2016-06-01

    For decades, polycrystalline CdTe thin films for solar applications have been restricted to grain sizes of microns or less whereas other semiconductors such as silicon and perovskites have produced devices with grains ranging from less than a micron to more than 1 mm. Because the lifetimes in as-deposited polycrystalline CdTe films are typically limited to less than a few hundred picoseconds, a CdCl2 treatment is generally used to improve the lifetime; but this treatment may limit the achievable hole density by compensation. Here, we establish methods to produce CdTe films with grain sizes ranging from hundreds of nanometers to several hundred microns by close-spaced sublimation at industrial manufacturing growth rates. Two-photon excitation photoluminescence spectroscopy shows a positive correlation of lifetime with grain size. Large-grain, as-deposited CdTe exhibits lifetimes exceeding 10 ns without Cl, S, O, or Cu. This uncompensated material allows dopants such as P to achieve a hole density of 1016 cm-3, which is an order of magnitude higher than standard CdCl2-treated devices, without compromising the lifetime.

  2. Properties of electrophoretically deposited single wall carbon nanotube films

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Junyoung; Jalali, Maryam; Campbell, Stephen A., E-mail: campb001@umn.edu

    2015-08-31

    This paper describes techniques for rapidly producing a carbon nanotube thin film by electrophoretic deposition at room temperature and determines the film mass density and electrical/mechanical properties of such films. The mechanism of electrophoretic deposition of thin layers is explained with experimental data. Also, film thickness is measured as a function of time, electrical field and suspension concentration. We use Rutherford backscattering spectroscopy to determine the film mass density. Films created in this manner have a resistivity of 2.14 × 10{sup −3} Ω·cm, a mass density that varies with thickness from 0.12 to 0.54 g/cm{sup 3}, and a Young's modulus between 4.72 and 5.67 GPa. The latter was found to be independent of thickness from 77 to 134 nm. We also report on fabricating free-standing films by removing the metal seed layer under the CNT film, and selectively etching a sacrificial layer. This method could be extended to flexible photovoltaic devices or high frequency RF MEMS devices. - Highlights: • We explain the electrophoretic deposition process and mechanism of thin SWCNT film deposition. • Characterization of the SWCNT film properties including density, resistivity, transmittance, and Young's modulus. • The film density and resistivity are found to be a function of the film thickness. • Techniques developed to create free standing layers of SW-CNTs for flexible electronics and mechanical actuators.

  3. Bismuth thin films obtained by pulsed laser deposition

    Science.gov (United States)

    Flores, Teresa; Arronte, Miguel; Rodriguez, Eugenio; Ponce, Luis; Alonso, J. C.; Garcia, C.; Fernandez, M.; Haro, E.

    1999-07-01

    In the present work Bi thin films were obtained by Pulsed Laser Deposition, using Nd:YAG lasers. The films were characterized by optical microscopy. Raman spectroscopy and X-rays diffraction. It was accomplished the real time spectral emission characterization of the plasma generated during the laser evaporation process. Highly oriented thin films were obtained.

  4. High efficiency CSS CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ferekides, C.S.; Marinskiy, D.; Viswanathan, V.; Tetali, B.; Palekis, V.; Selvaraj, P.; Morel, D.L. [University of South Florida, Tampa, FL (United States). Dept. of Electrical Engineering

    2000-02-21

    Cadmium telluride (CdTe) has long been recognized as a strong candidate for thin film solar cell applications. It has a bandgap of 1.45 eV, which is nearly ideal for photovoltaic energy conversion. Due to its high optical absorption coefficient essentially all incident radiation with energy above its band-gap is absorbed within 1-2 {mu}m from the surface. Thin film CdTe solar cells are typically heterojunctions, with cadmium sulfide (CdS) being the n-type junction partner. Small area efficiencies have reached the 16.0% level and considerable efforts are underway to commercialize this technology. This paper will present work carried out at the University South Florida sponsored by the National Renewable Energy Laboratory of the United States Department of Energy, on CdTe/CdS solar cells fabricated using the close spaced sublimation (CSS) process. The CSS technology has attractive features for large area applications such as high deposition rates and efficient material utilization. The structural and optical properties of CSS CdTe and CdS films and junctions will be presented and the influence of some important CSS process parameters will be discussed. (orig.)

  5. Deposition of copper selenide thin films and nanoparticles

    Science.gov (United States)

    Hu, Yunxiang; Afzaal, Mohammad; Malik, Mohammad A.; O'Brien, Paul

    2006-12-01

    A new method is reported for the growth of copper selenide thin films and nanoparticles using copper acetylacetonate and trioctylphosphine selenide. Aerosol-assisted chemical vapor deposition experiments lead to successful deposition of tetragonal Cu 2Se films. In contrast, hexadecylamine capped nanoparticles are composed of cubic Cu 2-xSe. The deposited materials are optically and structurally characterized. The results of this comprehensive study are described and discussed.

  6. Controlled cadmium telluride thin films for solar cell applications (emerging materials systems for solar cell applications). Quarterly progress report No. 1, April 9-July 8, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Vedam, K.

    1979-08-01

    Preparation and properties of cadmium telluride thin films for use in solar cells are studied. CdTe sputter deposition, crystal doping, and carrier typing are discussed. Future experimental plans are described. (WHK)

  7. Effects of deposition time in chemically deposited ZnS films in acidic solution

    Energy Technology Data Exchange (ETDEWEB)

    Haddad, H.; Chelouche, A., E-mail: azeddinechelouche@gmail.com; Talantikite, D.; Merzouk, H.; Boudjouan, F.; Djouadi, D.

    2015-08-31

    We report an experimental study on the synthesis and characterization of zinc sulfide (ZnS) single layer thin films deposited on glass substrates by chemical bath deposition technique in acidic solution. The effect of deposition time on the microstructure, surface morphology, optical absorption, transmittance, and photoluminescence (PL) was investigated by X-ray diffraction (XRD), scanning electronic microscopy (SEM), UV-Vis–NIR spectrophotometry and photoluminescence (PL) spectroscopy. The results showed that the samples exhibit wurtzite structure and their crystal quality is improved by increasing deposition time. The latter, was found to affect the morphology of the thin films as showed by SEM micrographs. The optical measurements revealed a high transparency in the visible range and a dependence of absorption edge and band gap on deposition time. The room temperature PL spectra indicated that all ZnS grown thin films emit a UV and blue light, while the band intensities are found to be dependent on deposition times. - Highlights: • Single layer ZnS thin films were deposited by CBD in acidic solution at 95 °C. • The effect of deposition time was investigated. • Coexistence of ZnS and ZnO hexagonal structures for time deposition below 2 h • Thicker ZnS films were achieved after monolayer deposition for 5 h. • The highest UV-blue emission observed in thin film deposited at 5 h.

  8. Spatial atomic layer deposition of zinc oxide thin films

    NARCIS (Netherlands)

    Illiberi, A.; Roozeboom, F.; Poodt, P.W.G.

    2012-01-01

    Zinc oxide thin films have been deposited at high growth rates (up to ~1 nm/s) by spatial atomic layer deposition technique at atmospheric pressure. Water has been used as oxidant for diethylzinc (DEZ) at deposition temperatures between 75 and 250 °C. The electrical, structural (crystallinity and mo

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

    Science.gov (United States)

    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.

  10. Resonant infrared pulsed laser deposition of thin biodegradable polymer films

    DEFF Research Database (Denmark)

    Bubb, D.M.; Toftmann, B.; Haglund Jr., R.F.

    2002-01-01

    Thin films of the biodegradable polymer poly(DL-lactide-co-glycolide) (PLGA) were deposited using resonant infrared pulsed laser deposition (RIR-PLD). The output of a free-electron laser was focused onto a solid target of the polymer, and the films were deposited using 2.90 (resonant with O-H str...... absorbance spectrum of the films is nearly identical with that of the native polymer, the average molecular weight of the films is a little less than half that of the starting material. Potential strategies for defeating this mass change are discussed.......Thin films of the biodegradable polymer poly(DL-lactide-co-glycolide) (PLGA) were deposited using resonant infrared pulsed laser deposition (RIR-PLD). The output of a free-electron laser was focused onto a solid target of the polymer, and the films were deposited using 2.90 (resonant with O......-H stretch) and 3.40 (C-H) mum light at macropulse fluences of 7.8 and 6.7 J/cm(2), respectively. Under these conditions, a 0.5-mum thick film can be grown in less than 5 min. Film structure was determined from infrared absorbance measurements and gel permeation chromatography (GPC). While the infrared...

  11. Crystalline Indium Sulphide thin film by photo accelerated deposition technique

    Science.gov (United States)

    Dhanya, A. C.; Preetha, K. C.; Deepa, K.; Remadevi, T. L.

    2015-02-01

    Indium sulfide thin films deserve special attention because of its potential application as buffer layers in CIGS based solar cells. Highly transparent indium sulfide (InS) thin films were prepared using a novel method called photo accelerated chemical deposition (PCD). Ultraviolet source of 150 W was used to irradiate the solution. Compared to all other chemical methods, PCD scores its advantage for its low cost, flexible substrate and capable of large area of deposition. Reports on deposition of high quality InS thin films at room temperature are very rare in literature. The precursor solution was initially heated to 90°C for ten minutes and then deposition was carried out at room temperature for two hours. The appearance of the film changed from lemon yellow to bright yellow as the deposition time increased. The sample was characterized for its structural and optical properties. XRD profile showed the polycrystalline behavior of the film with mixed phases having crystallite size of 17 nm. The surface morphology of the films exhibited uniformly distributed honey comb like structures. The film appeared to be smooth and the value of extinction coefficient was negligible. Optical measurements showed that the film has more than 80% transmission in the visible region. The direct band gap energy was 2.47eV. This method is highly suitable for the synthesis of crystalline and transparent indium sulfide thin films and can be used for various photo voltaic applications.

  12. Nanocrystalline Diamond Films Deposited by Electron Assisted Hot Filament Chemical Vapor Deposition

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nanocrystalline diamond films were deposited on polished Si wafer surface with electron assisted hot filament chemical vapor deposition at 1 kPa gas pressure, the deposited films were characterized and observed by Raman spectrum, X-ray diffraction, atomic force microscopy and semiconductor characterization system. The results show that when 8 A bias current is applied for 5 h, the surface roughness decreases to 28.5 nm. After 6 and 8 A bias current are applied for 1 h, and the nanocrystalline films deposition continue for 4 h with 0 A bias current at 1 kPa gas pressure. The nanocrystalline diamond films with 0.5×109 and 1×1010 Ω·cm resistivity respectively are obtained. It is demonstrated that electron bombardment plays an important role of nucleation to deposit diamond films with smooth surface and high resistivity.

  13. The effects of CdS processing and glass substrates on the performance of CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ferekides, C.S.; Dugan, K.; Ceekala, V.; Killian, J.; Oman, D.; Swaminathan, R.; Morel, D.L. [Univ. of South Florida, Tampa, FL (United States). Dept. of Electrical Engineering

    1994-12-31

    Cadmium Sulfide films prepared by rf sputtering and close spaced sublimation (CSS) have been used for the fabrication of CdTe/CdS thin film solar cells on borosilicate glass substrates. The CdTe layer was prepared by CSS at high processing temperatures (600 C). CdS films prepared by the chemical bath deposition process (CBD) were deposited on tin oxide coated soda lime glass substrates. For these devices the CSS CdTe films were prepared at low substrate temperatures (< 550 C). Devices prepared at low processing temperatures (CdTe-CSS/CdS-CBD) on soda lime glass substrates exhibited efficiencies in excess of 13% as measured under AM 1.5 conditions at the National Renewable Energy Laboratory.

  14. Construção e caracterização de células solares de filmes finos de CdS e CdTe

    OpenAIRE

    Morales Morales, Oswaldo [UNESP

    2012-01-01

    Neste trabalho, o objeto de estudo foi células Solares CdS/CdTe. Estas células usam o filme de sulfeto de cádmio (CdS) como semicondutor do tipo n e o filme de telureto de cádmio (CdTe) como semicondutor do tipo p. O recorde mundial, alcançado no laboratório, para estas células é 16,5% de eficiência. Nos Laboratórios do Departamento de Física e Química de Unesp - Ilha Solteira, este trabalho é pioneiro na fabricação de Células Solares de CdS/CdTe. Para realizar este trabalho foi necessário me...

  15. Band offsets for mismatched interfaces: The special case of ZnO on CdTe (001)

    Energy Technology Data Exchange (ETDEWEB)

    Jaffe, John E.; Kaspar, Tiffany C.; Droubay, Timothy C. [Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States); Varga, Tamas [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)

    2013-11-15

    High-quality planar interfaces between ZnO and CdTe would be useful in optoelectronic applications. Although CdTe is zinc blende with cubic lattice constant a = 6.482 Å while ZnO is hexagonal wurtzite with a = 3.253 Å and c = 5.213 Å, (001)-oriented cubic zinc blende ZnO films could be stabilized epitaxially on a CdTe (001) surface in an √2 × √2 R45° configuration with a lattice mismatch of <0.5%. Modeling such a configuration allows density-functional total-energy electronic-structure calculations to be performed on several interface arrangements (varying terminations and in-plane fractional translations) to identify the most likely form of the interface, and to predict valence-band offsets between CdTe and ZnO in each case. Growth of ZnO on Te-terminated CdTe(001) is predicted to produce small or even negative (CdTe below ZnO) valence band offsets, resulting in a Type I band alignment. Growth on Cd-terminated CdTe is predicted to produce large positive offsets for a Type II alignment as needed, for example, in solar cells. To corroborate some of these predictions, thin layers of ZnO were deposited on CdTe(001) by pulsed laser deposition, and the band alignments of the resulting heterojunctions were determined from x-ray photoelectron spectroscopy measurements. Although zinc blende ZnO could not be confirmed, the measured valence band offset (2.0–2.2 eV) matched well with the predicted value.

  16. Understanding misfit strain releasing mechanisms via molecular dynamics simulations of CdTe growth on {112}zinc-blende CdS

    Science.gov (United States)

    Zhou, X. W.; Chavez, J. J.; Almeida, S.; Zubia, D.

    2016-07-01

    Molecular dynamics simulations have been used to analyse microstructures of CdTe films grown on {112} surfaces of zinc-blende CdS. Interestingly, CdTe films grow in ⟨331⟩ orientations as opposed to ⟨112⟩ epitaxial orientations. At the CdTe-{331}/CdS-{112} interface, however, there exists an axis that is parallel to the ⟨110⟩ orientation of both CdS and CdTe. It is the direction orthogonal to this ⟨110⟩ that becomes different, being ⟨116⟩ for CdTe and ⟨111⟩ for CdS, respectively. Missing CdTe-{110} planes are found along the ⟨110⟩ axis, suggesting that the misfit strain is released by the conventional misfit dislocation mechanism along this axis. In the orthogonal axis, the misfit strain is found to be more effectively released by the new grain orientation mechanism. Our finding is supported by literature experimental observations of the change of growth direction when Cd0.96Zn0.04Te films are deposited on GaAs. Analyses of energetics clearly demonstrate the cause for the formation of the new orientation, and the insights gained from our studies can help understand the grain structures experimentally observed in lattice mismatched systems.

  17. Iridium thin films deposited via pulsed laser deposition for future applications as transition-edge sensors

    Energy Technology Data Exchange (ETDEWEB)

    Galeazzi, M. E-mail: galeazzi@physics.miami.edu; Chen, C.; Cohn, J.L.; Gundersen, J.O

    2004-03-11

    The University of Miami has recently started developing and studying high-resolution microcalorimeters operating near 100 mK for X-ray and particle physics and astrophysics. These detectors will be based on Transition Edge Sensors technology fabricated using iridium thin films deposited via the Pulsed Laser Deposition technique. We report here the preliminary result of the room temperature characterization of the Ir thin films, and an overview of future plans to use the films as transition edge sensors.

  18. Sputtering deposition and characterization of ultrathin amorphous carbon films

    Science.gov (United States)

    Lu, Wei

    1999-11-01

    This dissertation focuses on experimental investigations of ultrathin, ultrasmooth amorphous carbon (a-C) films deposited on Si(100) substrates by radio frequency (RF) sputtering and characterization of the nanomechanical and nanotribological properties and thermal stability of the films. Ultrathin a-C films of thickness 5--100 nm and typical root-mean-square roughness of 0.15--1 nm were deposited on ultrasmooth Si(100) substrates using pure argon as the sputtering gas. A low-pressure RF argon discharge model was used to analyze the plasma parameters in the film growth environment. These plasma parameters correlate the deposition conditions with the film growth processes. Atomic force microscopy (AFM) and surface force microscopy (SFM) were used to characterize the nanomechanical and nanotribological properties of the a-C films. X-ray photoelectron spectroscopy (XPS) was used to investigate the compositions and microstructures of the films. Sputter-etching measurements of the a-C films by energetic argon ion bombardment were used to study the surface binding energy of carbon atoms in a-C films deposited under different conditions. The dependence of film properties on deposition conditions was studied, and relations between nanomechanical and nanotribological properties were discussed in terms of a modified deformation index. The deformation and nanotribology mechanisms of the a-C films were compared with those of other films, such as TiC and Cr films (both 100 nm thick), and bulk Si(100). Reactive RF sputtering of nitrogenated amorphous carbon (a-CNx) films was investigated by introducing nitrogen into the a-C films during film growth by using an argon-nitrogen gas mixture as the sputtering gas. The alloying effect of nitrogen on the film growth and properties, such as hardness and surface energy, was studied and interpreted in terms of the changes in the plasma environment induced due to differences in the composition of the sputtering gas mixture. The thermal

  19. CdS薄膜的制备及其在CdTe电池中的应用%Preparation of CdS films and their application in CdTe solar cells

    Institute of Scientific and Technical Information of China (English)

    韩俊峰; 廖成; 江涛; 赵夔

    2011-01-01

    The CdTe solar cell is one of the most popular thin film PV devices, and CdS is used as a suitable window layer for CdTe-based photovoltaic systems. The CdS films here were prepared by chemical bath depostion (CBD) and closed space sublimation (CSS). The complete CdTe/CdS solar cell devices were fabricated and analyzed. It was found that the films prepared by the CSS method have larger grains and better optical/electrical properties. The photoelectric conversion efficiency of such a solar cell comes up to 10.9%. The films deposited by CSS method is fast in vacuum system and suitable for commercial applications.%CdTe薄膜电池是发展最快、应用前景最好的一类太阳能电池.CdS层是CdTe电池的窗口层材.料,其薄膜质量直接影响电池的转换效率.本文介绍了化学水浴沉积(CBD)和闭空间升华(CSS)两种方法沉积CdS薄膜,并完成单电池器件的制备和测试.CSS方法制备的薄膜结晶较大,光学和电学性能好于CBD方法制备的薄膜,太阳能电池的光电转换效率达到10.9%.CSS方法镀膜速度快,真空环境工作,有利于大规模产业化应用.

  20. Micro through nanostructure investigations of polycrystalline CdTe: Correlations with processing and electronic structures

    Energy Technology Data Exchange (ETDEWEB)

    Levi, D.H.; Moutinho, H.R.; Hasoon, F.A.; Keyes, B.M.; Ahrenkiel, R.K.; Al-Jassim, M.; Kazmerski, L.L. [National Renewable Energy Lab., Golden, CO (United States); Birkmire, R.W. [Univ. of Delaware, Newark, DE (United States). Inst. of Energy Conversion

    1994-12-31

    This paper provides first-time correlations of the nanoscale physical structure with the macroscale electronic and optical properties of CdTe/CdS thin films for several standard deposition techniques. Atomic force microscopy (AFM) was used to determine the micro and nanostructures of polycrystalline CdTe thin films used in photovoltaic (PV) cell fabrication. Photoluminescence (PL) was used to determine band gap, relative defect density, and photoexcited carrier lifetime. Nanostructural features (nanograins), beyond the spatial resolution of conventional scanning electron microscopy (SEM), were observed and characterized in as-deposited CdTe. The correlations of the proximal probe measurements of the physical structure with the optically determined electronic properties were used to show the effects of the chemical and heat processing, directly and conclusively. A particularly striking effect with important implications for PV applications is the diffusion of sulfur across the CdTe/CdS interface during heat treatment.

  1. Dual Ion Beam Deposition Of Diamond Films On Optical Elements

    Science.gov (United States)

    Deutchman, Arnold H.; Partyka, Robert J.; Lewis, J. C.

    1990-01-01

    Diamond film deposition processes are of great interest because of their potential use for the formation of both protective as well as anti-reflective coatings on the surfaces of optical elements. Conventional plasma-assisted chemical vapor deposition diamond coating processes are not ideal for use on optical components because of the high processing temperatures required, and difficulties faced in nucleating films on most optical substrate materials. A unique dual ion beam deposition technique has been developed which now makes possible deposition of diamond films on a wide variety of optical elements. The new DIOND process operates at temperatures below 150 aegrees Farenheit, and has been used to nucleate and grow both diamondlike carbon and diamond films on a wide variety of optical :taterials including borosilicate glass, quartz glass, plastic, ZnS, ZnSe, Si, and Ge.

  2. Chemical bath ZnSe thin films: deposition and characterisation

    Science.gov (United States)

    Lokhande, C. D.; Patil, P. S.; Ennaoui, A.; Tributsch, H.

    1998-01-01

    The zinc selenide (ZnSe) thin films have been deposited by a simple and inexpensive chemical bath deposition (CBD) method. The selenourea was used as a selenide ion source. The ZnSe films have been characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDAX), Rutherford back scattering (RBS), and optical absorption. The as-deposited ZnSe films on various substrates are found to be amorphous and contain O2 and N2 in addition to Zn and Se. The optical band gap of the film is estimated to be 2.9 eV. The films are photoactive as evidenced by time resolved microwave conductivity (TRMC).

  3. ZnS thin film deposited with chemical bath deposition process directed by different stirring speeds

    Science.gov (United States)

    Zhang, Y.; Dang, X. Y.; Jin, J.; Yu, T.; Li, B. Z.; He, Q.; Li, F. Y.; Sun, Y.

    2010-09-01

    In this combined film thickness, scanning electron microscopy (SEM), X-ray diffraction and optical properties study, we explore the effects of different stirring speeds on the growth and optical properties of ZnS film deposited by CBD method. From the disclosed changes of thickness of ZnS film, we conclude that film thickness is independent of the stirring speeds in the heterogeneous process (deposition time less than 40 min), but increases with the stirring speeds and/or deposition time increasing in the homogeneous process. Grazing incident X-ray diffraction (GIXRD) and the study of optical properties disclosed that the ZnS films grown with different stirring speeds show partially crystallized film and exhibit good transmittance (70-88% in the visible region), but the stirring speeds cannot give much effects on the structure and optical properties in the homogeneous process.

  4. Hardness and stress of amorphous carbon film deposited by glow discharge and ion beam assisting deposition

    CERN Document Server

    Marques, F C

    2000-01-01

    The hardness and stress of amorphous carbon films prepared by glow discharge and by ion beam assisting deposition are investigated. Relatively hard and almost stress free amorphous carbon films were deposited by the glow discharge technique. On the other hand, by using the ion beam assisting deposition, hard films were also obtained with a stress of the same order of those found in tetrahedral amorphous carbon films. A structural analysis indicates that all films are composed of a sp sup 2 -rich network. These results contradict the currently accepted concept that both stress and hardness are only related to the concentration of sp sup 3 sites. Furthermore, the same results also indicate that the sp sup 2 sites may also contribute to the hardness of the films.

  5. Nitrogen incorporation in sputter deposited molybdenum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stöber, Laura, E-mail: laura.stoeber@tuwien.ac.at; Patocka, Florian, E-mail: florian.patocka@tuwien.ac.at; Schneider, Michael, E-mail: michael.schneider@tuwien.ac.at; Schmid, Ulrich, E-mail: ulrich.e366.schmid@tuwien.ac.at [Institute of Sensor and Actuator Systems, TU Wien, Gußhausstraße 27-29, A-1040 Vienna (Austria); Konrath, Jens Peter, E-mail: jenspeter.konrath@infineon.com; Haberl, Verena, E-mail: verena.haberl@infineon.com [Infineon Technologies Austria AG, Siemensstraße 2, 9500 Villach (Austria)

    2016-03-15

    In this paper, the authors report on the high temperature performance of sputter deposited molybdenum (Mo) and molybdenum nitride (Mo{sub 2}N) thin films. Various argon and nitrogen gas compositions are applied for thin film synthetization, and the amount of nitrogen incorporation is determined by Auger measurements. Furthermore, effusion measurements identifying the binding conditions of the nitrogen in the thin film are performed up to 1000 °C. These results are in excellent agreement with film stress and scanning electron microscope analyses, both indicating stable film properties up to annealing temperatures of 500 °C.

  6. Continuous wave infrared laser deposition of organic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yaginuma, Seiichiro [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503 (Japan); Yamaguchi, Jun [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503 (Japan); Haemori, Masamitsu [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503 (Japan); Itaka, Kenji [Department of Advanced Materials Science, Graduate School of Frontier Sciences, Univesity of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8568 (Japan); Matsumoto, Yuji [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503 (Japan); Kondo, Michio [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503 (Japan); Koinuma, Hideomi [Department of Advanced Materials Science, Graduate School of Frontier Sciences, Univesity of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8568 (Japan)

    2007-04-15

    We developed a continuous-wave infrared laser molecular beam epitaxy (CW-IR-LMBE) optimized for the fabrication of organic semiconductor films. The crystal quality of these organic thin films deposited by CW-IR-LMBE was substantially the same as those deposited by thermal evaporation. Due to the possibility of quick switching of evaporation sources, CW-IR-LMBE is especially advantageous for rapid screening of composition, thickness, and fabrication parameters in materials and device optimization based on combinatorial technology.

  7. Thin film zinc oxide deposited by CVD and PVD

    Science.gov (United States)

    Hamelmann, Frank U.

    2016-10-01

    Zinc oxide is known as a mineral since 1810, but it came to scientific interest after its optoelectronic properties found to be tuneable by p-type doping. Since the late 1980’s the number of publications increased exponentially. All thin film deposition technologies, including sol-gel and spray pyrolysis, are able to produce ZnO films. However, for outstanding properties and specific doping, only chemical vapor deposition and physical vapor deposition have shown so far satisfying results in terms of high conductivity and high transparency. In this paper the different possibilities for doping will be discussed, some important applications of doped ZnO thin films will be presented. The deposition technologies used for industrial applications are shown in this paper. Especially sputtering of aluminium doped Zinc Oxide (ZnO:Al or AZO) and LPCVD of boron doped Zinc Oxide (ZnO:B or BZO) are used for the commercial production of transparent conductive oxide films on glass used for thin film photovoltaic cells. For this special application the typical process development for large area deposition is presented, with the important trade-off between optical properties (transparency and ability for light scattering) and electrical properties (conductivity). Also, the long term stability of doped ZnO films is important for applications, humidity in the ambient is often the reason for degradation of the films. The differences between the mentioned materials are presented.

  8. Recent Developments of Flexible CdTe Solar Cells on Metallic Substrates: Issues and Prospects

    Directory of Open Access Journals (Sweden)

    M. M. Aliyu

    2012-01-01

    Full Text Available This study investigates the key issues in the fabrication of CdTe solar cells on metallic substrates, their trends, and characteristics as well as effects on solar cell performance. Previous research works are reviewed while the successes, potentials, and problems of such technology are highlighted. Flexible solar cells offer several advantages in terms of production, cost, and application over glass-based types. Of all the metals studied as substrates for CdTe solar cells, molybdenum appears the most favorable candidate, while close spaced sublimation (CSS, electrodeposition (ED, magnetic sputtering (MS, and high vacuum thermal evaporation (HVE have been found to be most common deposition technologies used for CdTe on metal foils. The advantages of these techniques include large grain size (CSS, ease of constituent control (ED, high material incorporation (MS, and low temperature process (MS, HVE, ED. These invert-structured thin film CdTe solar cells, like their superstrate counterparts, suffer from problems of poor ohmic contact at the back electrode. Thus similar strategies are applied to minimize this problem. Despite the challenges faced by flexible structures, efficiencies of up to 13.8% and 7.8% have been achieved in superstrate and substrate cell, respectively. Based on these analyses, new strategies have been proposed for obtaining cheaper, more efficient, and viable flexible CdTe solar cells of the future.

  9. Characterization of polymer thin films obtained by pulsed laser deposition

    Science.gov (United States)

    Palla-Papavlu, A.; Dinca, V.; Ion, V.; Moldovan, A.; Mitu, B.; Luculescu, C.; Dinescu, M.

    2011-04-01

    The development of laser techniques for the deposition of polymer and biomaterial thin films on solid surfaces in a controlled manner has attracted great attention during the last few years. Here we report the deposition of thin polymer films, namely Polyepichlorhydrin by pulsed laser deposition. Polyepichlorhydrin polymer was deposited on flat substrate (i.e. silicon) using an NdYAG laser (266 nm, 5 ns pulse duration and 10 Hz repetition rate). The obtained thin films have been characterized by atomic force microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and spectroscopic ellipsometry. It was found that for laser fluences up to 1.5 J/cm 2 the chemical structure of the deposited polyepichlorhydrin polymer thin layers resembles to the native polymer, whilst by increasing the laser fluence above 1.5 J/cm 2 the polyepichlorohydrin films present deviations from the bulk polymer. Morphological investigations (atomic force microscopy and scanning electron microscopy) reveal continuous polyepichlorhydrin thin films for a relatively narrow range of fluences (1-1.5 J/cm 2). The wavelength dependence of the refractive index and extinction coefficient was determined by ellipsometry studies which lead to new insights about the material. The obtained results indicate that pulsed laser deposition method is potentially useful for the fabrication of polymer thin films to be used in applications including electronics, microsensor or bioengineering industries.

  10. Stress development during deposition of CNx thin films

    Science.gov (United States)

    Broitman, E.; Zheng, W. T.; Sjöström, H.; Ivanov, I.; Greene, J. E.; Sundgren, J.-E.

    1998-05-01

    We have investigated the influence of deposition parameters on stress generation in CNx (0.3films deposited onto Si(001) substrates by reactive magnetron sputtering of C in pure N2 discharges. Film stress, σ, which in all cases is compressive, decreases with an increase in the N2 pressure, PN2, due to structural changes induced by the pressure-dependent variation in the average energy of particles bombarding the film during deposition. The film stress σ is also a function of the film growth temperature, Ts, and exhibits a maximum value of ˜5 GPa at 350 °C. Under these conditions, the films have a distorted microstructure consisting of a three-dimensional, primarily sp2 bonded, network. In contrast, films deposited at Ts<200 °C with a low stress are amorphous. At 350 °Cfilms grown at 350 °C exhibit the highest hardness and elasticity.

  11. Pulsed laser deposition and characterisation of thin superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Morone, A. [CNR, zona industriale di Tito Scalo, Potenza (Italy). Istituto per i Materiali Speciali

    1996-09-01

    Same concepts on pulsed laser deposition of thin films will be discussed and same examples of high transition temperature (HTc) BiSrCaCuO (BISCO) and low transition temperature NbN/MgO/NbN multilayers will be presented. X-ray and others characterizations of these films will be reported and discussed. Electrical properties of superconducting thin films will be realized as a function of structural and morphological aspect.

  12. Vacuum deposition of stoichiometric crystalline PbS films: The effect of sulfurizing environment during deposition

    Science.gov (United States)

    Singh, B. P.; Kumar, R.; Kumar, A.; Tyagi, R. C.

    2015-10-01

    Thin film of lead sulfide (PbS) was deposited onto highly cleaned glass and quartz substrates using a vacuum thermal evaporation technique. The effect of the sulfurizing environment on the growth and properties of vacuum-deposited PbS thin film was studied. The ambient sulfurizing environment was created by thermal decomposition of thiourea inside the vacuum chamber during deposition to maintain the stoichiometry and quality of the PbS film. The sulfurizing gas H2S, produced in the thermal decomposition of the solid sulfur containing thiourea readily combines with the cations (Pb2+) without leaving any anions (S2-) at the substrates and also has not produced any excess of sulfur at the substrates. The deposited film was characterized by optical spectroscopy, x-ray diffraction patterns, scanning electron micrographs with energy dispersive analysis of x-rays, and atomic force micrographs. The physical characterization of the deposited PbS film revealed that the surface of film grown in the sulfurizing environment improved and contained more stoichiometric sulfur in comparison to film deposited without the sulfurizing environment.

  13. Stoichiometry controlled oxide thin film growth by pulsed laser deposition

    NARCIS (Netherlands)

    Groenen, Rik; Smit, Jasper; Orsel, Kasper; Vailionis, Arturas; Bastiaens, Bert; Huijben, Mark; Boller, Klaus; Rijnders, Guus; Koster, Gertjan

    2015-01-01

    The oxidation of species in the plasma plume during pulsed laser deposition controls both the stoichiometry as well as the growth kinetics of the deposited SrTiO3 thin films, instead of the commonly assumed mass distribution in the plasma plume and the kinetic energy of the arriving species. It was

  14. Ubiquitous pentacene monolayer on metals deposited onto pentacene films.

    Science.gov (United States)

    Jaeckel, B; Sambur, J B; Parkinson, B A

    2007-11-01

    Photoelectron spectroscopy (XPS and UPS) was used to study the deposition of metal layers (Ag, Cu, and Au) onto pentacene films. Very low work functions were measured (PhiAg = 3.91 eV, PhiCu = 3.93 eV, and PhiAu = 4.3 eV) for all of the metals, in agreement with results from the literature. The intensities of the C 1s core-level signals from pentacene that were monitored during stepwise metal deposition leveled off at a value of about 30% of a thick pentacene film. This C 1s intensity is comparable to that of one monolayer of pentacene deposited onto the respective metal. The valence band spectra of metals deposited onto pentacene and spectra collected for pentacene deposited onto bare metal surfaces are very similar. These findings lead to the conclusion that approximately one monolayer of pentacene is always present on top of the freshly deposited metal film, which explains the very low work function of the metals when they are deposited onto organic films. We expect similar behavior with other nonreactive metals deposited onto stable organic layers.

  15. Self-terminating growth of platinum films by electrochemical deposition.

    Science.gov (United States)

    Liu, Yihua; Gokcen, Dincer; Bertocci, Ugo; Moffat, Thomas P

    2012-12-07

    A self-terminating rapid electrodeposition process for controlled growth of platinum (Pt) monolayer films from a K(2)PtCl(4)-NaCl electrolyte has been developed that is tantamount to wet atomic layer deposition. Despite the deposition overpotential being in excess of 1 volt, Pt deposition was quenched at potentials just negative of proton reduction by an alteration of the double-layer structure induced by a saturated surface coverage of underpotential deposited H (H(upd)). The surface was reactivated for further Pt deposition by stepping the potential to more positive values, where H(upd) is oxidized and fresh sites for the adsorption of PtCl(4)(2-) become available. Periodic pulsing of the potential enables sequential deposition of two-dimensional Pt layers to fabricate films of desired thickness, relevant to a range of advanced technologies.

  16. Thin-film organic photonics molecular layer deposition and applications

    CERN Document Server

    Yoshimura, Tetsuzo

    2011-01-01

    Among the many atomic/molecular assembling techniques used to develop artificial materials, molecular layer deposition (MLD) continues to receive special attention as the next-generation growth technique for organic thin-film materials used in photonics and electronics. Thin-Film Organic Photonics: Molecular Layer Deposition and Applications describes how photonic/electronic properties of thin films can be improved through MLD, which enables precise control of atomic and molecular arrangements to construct a wire network that achieves ""three-dimensional growth"". MLD facilitates dot-by-dot--o

  17. An optimized multilayer structure of CdS layer for CdTe solar cells application

    Energy Technology Data Exchange (ETDEWEB)

    Han Junfeng, E-mail: pkuhjf@gmail.com [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Road Yiheyuan 5, Beijing 100871 (China); Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Liao Cheng, E-mail: Cliao@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Road Yiheyuan 5, Beijing 100871 (China); Jiang Tao [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Road Yiheyuan 5, Beijing 100871 (China); Spanheimer, C.; Haindl, G.; Fu, Ganhua; Krishnakumar, V. [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Zhao Kui [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Road Yiheyuan 5, Beijing 100871 (China); Klein, A.; Jaegermann, W. [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany)

    2011-04-28

    Research highlights: > Two different methods to prepare CdS films for CdTe solar cells. > A new multilayer structure of window layer for the CdTe solar cell. > Thinner CdS window layer for the solar cell than the standard CdS layer. > Higher performance of solar cells based on the new multilayer structure. - Abstract: CdS layers grown by 'dry' (close space sublimation) and 'wet' (chemical bath deposition) methods are deposited and analyzed. CdS prepared with close space sublimation (CSS) has better crystal quality, electrical and optical properties than that prepared with chemical bath deposition (CBD). The performance of CdTe solar cell based on the CSS CdS layer has higher efficiency than that based on CBD CdS layer. However, the CSS CdS suffers from the pinholes. And consequently it is necessary to prepare a 150 nm thin film for CdTe/CdS solar cell. To improve the performance of CdS/CdTe solar cells, a thin multilayer structure of CdS layer ({approx}80 nm) is applied, which is composed of a bottom layer (CSS CdS) and a top layer (CBD CdS). That bi-layer film can allow more photons to pass through it and significantly improve the short circuit current of the CdS/CdTe solar cells.

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

    Science.gov (United States)

    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.

  19. Aluminosilicate glass thin films elaborated by pulsed laser deposition

    Science.gov (United States)

    Carlier, Thibault; Saitzek, Sébastien; Méar, François O.; Blach, Jean-François; Ferri, Anthony; Huvé, Marielle; Montagne, Lionel

    2017-03-01

    In the present work, we report the elaboration of aluminosilicate glass thin films by Pulsed Laser Deposition at various temperatures deposition. The amorphous nature of glass thin films was highlighted by Grazing Incidence X-Ray Diffraction and no nanocristallites were observed in the glassy matrix. Chemical analysis, obtained with X-ray Photoelectron Spectroscopy and Time of Flight Secondary Ion Mass Spectroscopy, showed a good transfer and homogeneous elementary distribution with of chemical species from the target to the film a. Structural studies performed by Infrared Spectroscopy showed that the substrate temperature plays an important role on the bonding configuration of the layers. A slight shift of Si-O modes to larger wavenumber was observed with the synthesis temperature, assigned to a more strained sub-oxide network. Finally, optical properties of thins film measured by Spectroscopic Ellipsometry are similar to those of the bulk aluminosilicate glass, which indicate a good deposition of aluminosilicate bulk glass.

  20. Aerosol deposition of (Cu,Ti) substituted bismuth vanadate films

    Energy Technology Data Exchange (ETDEWEB)

    Exner, Jörg, E-mail: Functional.Materials@Uni-Bayreuth.de [University of Bayreuth, Department of Functional Materials, Universitätsstraße 30, 95440 Bayreuth (Germany); Fuierer, Paul [Materials and Metallurgical Engineering Department, New Mexico Institute of Mining and Technology, Socorro, NM 87801 (United States); Moos, Ralf [University of Bayreuth, Department of Functional Materials, Universitätsstraße 30, 95440 Bayreuth (Germany)

    2014-12-31

    Bismuth vanadate, Bi{sub 4}V{sub 2}O{sub 11}, and related compounds with various metal (Me) substitutions, Bi{sub 4}(Me{sub x}V{sub 1−x}){sub 2}O{sub 11−δ}, show some of the highest ionic conductivities among the known solid oxide electrolytes. Films of Cu and Ti substituted bismuth vanadate were prepared by an aerosol deposition method, a spray coating process also described as room temperature impact consolidation. Resultant films, several microns in thickness, were dense with good adhesion to the substrate. Scanning electron microscopy and high temperature X-ray diffraction were used to monitor the effects of temperature on the structure and microstructure of the film. The particle size remained nano-scale while microstrain decreased rapidly up to 500 °C, above which coarsening and texturing increased rapidly. Impedance measurements of films deposited on inter-digital electrodes revealed an annealing effect on the ionic conductivity, with the conductivity exceeding that of a screen printed film, and approaching that of bulk ceramic. - Highlights: • Cu and Ti doped bismuth vanadate films were prepared by aerosol deposition (AD). • Dense 3–5 μm thick films were deposited on alumina, silicon and gold electrodes. • Annealing of the AD-layer increases the conductivity by 1.5 orders of magnitude. • Effect of temperature on structure and microstructure was investigated.

  1. Deposition of antimony telluride thin film by ECALE

    Institute of Scientific and Technical Information of China (English)

    GAO; Xianhui; YANG; Junyou; ZHU; Wen; HOU; Jie; BAO; Siqian; FAN; Xi'an; DUAN; Xingkai

    2006-01-01

    The process of Sb2Te3 thin film growth on the Pt substrate by electrochemical atomic layer epitaxy (ECALE) was studied. Cyclic voltammetric scanning was performed to analyze the electrochemical behavior of Te and Sb on the Pt substrate. Sb2Te3 film was formed using an automated flow deposition system by alternately depositing Te and Sb atomic layers for 400 circles. The deposited Sb2Te3 films were characterized by XRD, EDX, FTIR and FESEM observation. Sb2Te3 compound structure was confirmed by XRD pattern and agreed well with the results of EDX quantitative analysis and coulometric analysis. FESEM micrographs showed that the deposit was composed of fine nano particles with size of about 20 nm. FESEM image of the cross section showed that the deposited films were very smooth and dense with thickness of about 190 nm. The optical band gap of the deposited Sb2Te3 film was determined as 0.42 eV by FTIR spectroscopy, and it was blue shifted in comparison with that of the bulk Sb2Te3 single crystal due to its nanocrystalline microstructure.

  2. UV laser deposition of metal films by photogenerated free radicals

    Science.gov (United States)

    Montgomery, R. K.; Mantei, T. D.

    1986-01-01

    A novel photochemical method for liquid-phase deposition of metal films is described. In the liquid phase deposition scheme, a metal containing compound and a metal-metal bonded carbonyl complex are dissolved together in a polar solvent and the mixture is irradiated using a UV laser. The optical arrangement consists of a HeCd laser which provides 7 mW of power at a wavelength of 325 nm in the TEM(OO) mode. The beam is attenuated and may be expanded to a diameter of 5-20 mm. Experiments with photochemical deposition of silver films onto glass and quartz substrates are described in detail. Mass spectrometric analysis of deposited silver films indicated a deposition rate of about 1 A/s at incident power levels of 0.01 W/sq cm. UV laser-induced copper and palladium films have also been obtained. A black and white photograph showing the silver Van Der Pauw pattern of a solution-deposited film is provided.

  3. Microreactor-Assisted Solution Deposition for Compound Semiconductor Thin Films

    Directory of Open Access Journals (Sweden)

    Chang-Ho Choi

    2014-05-01

    Full Text Available State-of-the-art techniques for the fabrication of compound semiconductors are mostly vacuum-based physical vapor or chemical vapor deposition processes. These vacuum-based techniques typically operate at high temperatures and normally require higher capital costs. Solution-based techniques offer opportunities to fabricate compound semiconductors at lower temperatures and lower capital costs. Among many solution-based deposition processes, chemical bath deposition is an attractive technique for depositing semiconductor films, owing to its low temperature, low cost and large area deposition capability. Chemical bath deposition processes are mainly performed using batch reactors, where all reactants are fed into the reactor simultaneously and products are removed after the processing is finished. Consequently, reaction selectivity is difficult, which can lead to unwanted secondary reactions. Microreactor-assisted solution deposition processes can overcome this limitation by producing short-life molecular intermediates used for heterogeneous thin film synthesis and quenching the reaction prior to homogeneous reactions. In this paper, we present progress in the synthesis and deposition of semiconductor thin films with a focus on CdS using microreactor-assisted solution deposition and provide an overview of its prospect for scale-up.

  4. XPS Study of CdTe Thin Films Doped with Gd%掺Gd-CdTe薄膜的XPS研究

    Institute of Scientific and Technical Information of China (English)

    安晓晖; 李蓉萍; 田磊; 何志刚; 吴蓉; 李忠贤

    2012-01-01

    CdTe thin film doped with Gd has been obtained by vacuum evaporation technique with two sources , and chemical state has been studied by X-ray photo-electron spectroscopy. XPS data show that Cd,Te,O,C and Gd elements exist on the surface of the film. C1s and O1s binding energy indicates that the two elements mainly exist in the form of physical adsorption. The experiment results show that Cd and Te atoms exist in oxidation state as in well as in CdTe. Due to carbon pol-lution, Gd element does not appear on the surface, only appears in the etching process. Erosion analysis shows the Cd element s content is greater than Te, and the ratio between them tends to 1:0. 8.%应用双源法真空蒸发制备掺Gd的CdTe薄膜,并借助XPS对其进行组份分析.实验表明,Gd掺杂的CdTe薄膜的组分为Cd、Te、O、C、Gd等元素,其中C、O主要以物理吸附方式存在于薄膜表面;Cd、Te元素的存在方式为CdTe化合物及其氧化物形式;而Gd元素由于碳污染的原因在其表面未曾出现,只在刻蚀过程中出现;深度剥蚀分析表明在样品内部Cd元素的含量大于Te元素的含量,且接近于1∶0.8,趋于稳定.

  5. Investigation on Structure and Optical Properties of Gd-doped CdTe Films%Gd掺杂CdTe薄膜的结构和光学特性研究

    Institute of Scientific and Technical Information of China (English)

    何志刚; 李蓉萍; 董海成; 安晓晖; 吴蓉; 李忠贤

    2011-01-01

    CdTe thin films and Gd - doped CdTe thin films were prepared by vacuum thermal evaporation on glass substrates. The effect of heat - treatment and doping content of Gd on the structure, optical characteristics of CdTe films was studied. The results show that all thin films are cube sphalerite structure. Gd doping doesn't change crystal structure of thin films, but it makes average crystal size of CdTe films tum small, the lattice constant and crystal cell volume tum big appreciably, and a preferential growth orientation along [220] tum to along [ 111 ] . The transmissivity becomes higher in visible spectrad range and the optical band gap changes small by Cd doping.%用真空热蒸发法在玻璃衬底制备CdTe和Cd掺杂CdTe薄膜.研究热处理和Gd掺杂量对CdTe薄膜结构、光学特性的影响.结果表明,薄膜均为立方闪锌矿结构,Gd的掺入没有改变薄膜的晶体结构,但使薄膜的晶粒尺寸减小,晶格常数和晶胞体积略有增大,并使其择优取向由[220]晶向变为[111]晶向.掺Gd使薄膜在可见光范围透过率增强,但对光能隙影响不大.

  6. Sputter deposited Terfenol-D thin films for multiferroic applications

    Directory of Open Access Journals (Sweden)

    K. P. Mohanchandra

    2015-09-01

    Full Text Available In this paper, we study the sputter deposition and crystallization process to produce high quality Terfenol-D thin film (100 nm with surface roughness below 1.5 nm. The Terfenol-D thin film was produced using DC magnetron sputtering technique with various sputtering parameters and two different crystallization methods, i.e. substrate heating and post-annealing. Several characterization techniques including WDS, XRD, TEM, AFM, SQUID and MOKE were used to determine the physical and magnetic properties of the Terfenol-D films. TEM studies reveal that the film deposited on the heated substrate has large grains grown along the film thickness producing undesirable surface roughness while the film crystallized by post-annealing method shows uniformly distributed small grains producing a smooth surface. The Terfenol-D film was also deposited onto (011 cut PMN-PT single crystal substrate. With the application of an electric field the film exhibited a 1553 Oe change in coercivity with an estimated saturation magnetostriction of λs = 910 x 10−6.

  7. Sputter deposited Terfenol-D thin films for multiferroic applications

    Science.gov (United States)

    Mohanchandra, K. P.; Prikhodko, S. V.; Wetzlar, K. P.; Sun, W. Y.; Nordeen, P.; Carman, G. P.

    2015-09-01

    In this paper, we study the sputter deposition and crystallization process to produce high quality Terfenol-D thin film (100 nm) with surface roughness below 1.5 nm. The Terfenol-D thin film was produced using DC magnetron sputtering technique with various sputtering parameters and two different crystallization methods, i.e. substrate heating and post-annealing. Several characterization techniques including WDS, XRD, TEM, AFM, SQUID and MOKE were used to determine the physical and magnetic properties of the Terfenol-D films. TEM studies reveal that the film deposited on the heated substrate has large grains grown along the film thickness producing undesirable surface roughness while the film crystallized by post-annealing method shows uniformly distributed small grains producing a smooth surface. The Terfenol-D film was also deposited onto (011) cut PMN-PT single crystal substrate. With the application of an electric field the film exhibited a 1553 Oe change in coercivity with an estimated saturation magnetostriction of λs = 910 x 10-6.

  8. Defect control in room temperature deposited cadmium sulfide thin films by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Como, N. [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080 (United States); Martinez-Landeros, V. [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080 (United States); Centro de Investigación en Materiales Avanzados, Monterrey, Nuevo Leon, 66600, México (Mexico); Mejia, I. [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080 (United States); Aguirre-Tostado, F.S. [Centro de Investigación en Materiales Avanzados, Monterrey, Nuevo Leon, 66600, México (Mexico); Nascimento, C.D.; Azevedo, G. de M; Krug, C. [Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91509-900 (Brazil); Quevedo-Lopez, M.A., E-mail: mquevedo@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080 (United States)

    2014-01-01

    The control of defects in cadmium sulfide thin films and its impact on the resulting CdS optical and electrical characteristics are studied. Sulfur vacancies and cadmium interstitial concentrations in the CdS films are controlled using the ambient pressure during pulsed laser deposition. CdS film resistivities ranging from 10{sup −1} to 10{sup 4} Ω-cm are achieved. Hall Effect measurements show that the carrier concentration ranges from 10{sup 19} to 10{sup 13} cm{sup −3} and is responsible for the observed resistivity variation. Hall mobility varies from 2 to 12 cm{sup 2}/V-s for the same pressure regime. Although the energy bandgap remains unaffected (∼ 2.42 eV), the optical transmittance is reduced due to the increase of defects in the CdS films. Rutherford back scattering spectroscopy shows the dependence of the CdS films stoichiometry with deposition pressure. The presence of CdS defects is attributed to more energetic species reaching the substrate, inducing surface damage in the CdS films during pulsed laser deposition. - Highlights: • CdS thin films deposited by pulsed laser deposition at room temperature. • The optical, electrical and structural properties were evaluated. • Carrier concentration ranged from 10{sup 19} to 10{sup 13} cm{sup −3}. • The chemical composition was studied by Rutherford back scattering. • The density of sulfur vacancies and cadmium interstitial was varied.

  9. Large-Scale Graphene Film Deposition for Monolithic Device Fabrication

    Science.gov (United States)

    Al-shurman, Khaled

    Since 1958, the concept of integrated circuit (IC) has achieved great technological developments and helped in shrinking electronic devices. Nowadays, an IC consists of more than a million of compacted transistors. The majority of current ICs use silicon as a semiconductor material. According to Moore's law, the number of transistors built-in on a microchip can be double every two years. However, silicon device manufacturing reaches its physical limits. To explain, there is a new trend to shrinking circuitry to seven nanometers where a lot of unknown quantum effects such as tunneling effect can not be controlled. Hence, there is an urgent need for a new platform material to replace Si. Graphene is considered a promising material with enormous potential applications in many electronic and optoelectronics devices due to its superior properties. There are several techniques to produce graphene films. Among these techniques, chemical vapor deposition (CVD) offers a very convenient method to fabricate films for large-scale graphene films. Though CVD method is suitable for large area growth of graphene, the need for transferring a graphene film to silicon-based substrates is required. Furthermore, the graphene films thus achieved are, in fact, not single crystalline. Also, graphene fabrication utilizing Cu and Ni at high growth temperature contaminates the substrate that holds Si CMOS circuitry and CVD chamber as well. So, lowering the deposition temperature is another technological milestone for the successful adoption of graphene in integrated circuits fabrication. In this research, direct large-scale graphene film fabrication on silicon based platform (i.e. SiO2 and Si3N4) at low temperature was achieved. With a focus on low-temperature graphene growth, hot-filament chemical vapor deposition (HF-CVD) was utilized to synthesize graphene film using 200 nm thick nickel film. Raman spectroscopy was utilized to examine graphene formation on the bottom side of the Ni film

  10. High-quality AlN films grown on chemical vapor-deposited graphene films

    Directory of Open Access Journals (Sweden)

    Chen Bin-Hao

    2016-01-01

    Full Text Available We report the growth of high-quality AlN films on graphene. The graphene films were synthesized by CVD and then transferred onto silicon substrates. Epitaxial aluminum nitride films were deposited by DC magnetron sputtering on both graphene as an intermediate layer and silicon as a substrate. The structural characteristics of the AlN films and graphene were investigated. Highly c-axis-oriented AlN crystal structures are investigated based on the XRDpatterns observations.

  11. MOCVD of thin film photovoltaic solar cells—Next-generation production technology?

    Science.gov (United States)

    Irvine, S. J. C.; Barrioz, V.; Lamb, D.; Jones, E. W.; Rowlands-Jones, R. L.

    2008-11-01

    This paper will review the chalcogenide thin film photovoltaic (PV) solar cells, based on cadmium telluride (CdTe) and copper indium diselenide (CIS) and discuss the potential for metalorganic chemical vapour deposition (MOCVD) to enable more advanced devices in the second generation of CdTe module production. The current generation of production methods is based on physical vapour deposition (PVD) or close-spaced sublimation (CSS). This paper concentrates on the less well-known topic of MOCVD of thin film chalcogenide cells, and in particular that of CdTe. Efficient CdTe PV solar cells (>10% AM1.5) have been demonstrated from deposition of the CdS, CdTe and CdCl 2 films in a single MOCVD chamber. The CdTe layer was doped with As and an additional high As concentration CdTe layer provides effective low resistance contacting without the need for wet etching the surface. The high level of flexibility in using MOCVD has been demonstrated where the CdS window layer has been alloyed with Zn to improve the blue response of the PV device and improve AM1.5 efficiency to 13.3%.

  12. Degradation sources of CdTe thin film PV: CdCl{sub 2} residue and shunting pinholes

    Energy Technology Data Exchange (ETDEWEB)

    Gorji, Nima E. [University of Bologna, Department of Electrical, Electronics and Information Engineering, Bologna (Italy)

    2014-09-15

    The present work considers two observable phenomena through the experimental fabrication and electrical characterization of the rf-sputtered CdS/CdTe thin film solar cells that extremely reduce the overall conversion efficiency of the device: CdCl{sub 2} residue on the surface of the semiconductor and shunting pinholes. The former happens through nonuniform treatment of the As-deposited solar cells before annealing at high temperature and the latter occurs by shunting pinholes when the cell surface is shunted by defects, wire-like pathways or scratches on the metallic back contact caused from the external contacts. Such physical problems may be quite common in the experimental activities and reduce the performance down to 4-5 % which leads to dismantle the device despite its precise fabrication. We present our electrical characterization on the samples that received wet CdCl{sub 2} surface treatment (uniform or nonuniform) and are damaged by the pinholes. (orig.)

  13. Growth of tantalum pentoxide film by pulsed laser deposition

    Science.gov (United States)

    Zhang, Jun-Ying; Fang, Qi; Boyd, Ian W.

    1999-01-01

    Thin films of Ta 2O 5 have been deposited on quartz and silicon substrates by 532-nm (Nd:YAG) pulsed laser deposition (PLD) in various O 2 gas environments. The influence of the deposition parameters, such as oxygen pressure, substrate temperature and annealing under UV irradiation using a 172-nm excimer lamp, on the properties of the grown films, has been studied. The refractive index of the films increases with increasing pressure of O 2. X-ray diffraction measurements show that the as-deposited films are amorphous at temperatures below 500°C and possess orthorhombic (β-Ta 2O 5) crystal structure at temperatures above 600°C. The optical properties determined by UV spectrophotometry also strongly depend on the deposition parameters. At O 2 pressures above 0.15 mbar, the refractive index of the films was about 2.12 which is close to the bulk Ta 2O 5 value of 2.2. Optical transmittance around 85% in the visible region of the spectrum was obtained at an oxygen pressure of 0.2 mbar.

  14. Pulsed laser deposition of niobium nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Farha, Ashraf Hassan, E-mail: ahass006@odu.edu; Elsayed-Ali, Hani E., E-mail: helsayed@odu.edu [Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529 (United States); Applied Research Center, Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Department of Physics, Faculty of Science, Ain Shams University, Cairo 11566 (Egypt); Ufuktepe, Yüksel, E-mail: ufuk@cu.edu.tr [Department of Physics, University of Cukurova, 01330 Adana (Turkey); Myneni, Ganapati, E-mail: rao@jlab.org [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)

    2015-12-04

    Niobium nitride (NbN{sub x}) films were grown on Nb and Si(100) substrates using pulsed laser deposition. NbN{sub x} films were deposited on Nb substrates using PLD with a Q-switched Nd:YAG laser (λ = 1064 nm, ∼40 ns pulse width, and 10 Hz repetition rate) at different laser fluences, nitrogen background pressures and deposition substrate temperatures. When all the fabrication parameters are fixed, except for the laser fluence, the surface roughness, nitrogen content, and grain size increase with increasing laser fluence. Increasing nitrogen background pressure leads to a change in the phase structure of the NbN{sub x} films from mixed β-Nb{sub 2}N and cubic δ-NbN phases to single hexagonal β-Nb{sub 2}N. The substrate temperature affects the preferred orientation of the crystal structure. The structural and electronic, properties of NbN{sub x} deposited on Si(100) were also investigated. The NbN{sub x} films exhibited a cubic δ-NbN with a strong (111) orientation. A correlation between surface morphology, electronic, and superconducting properties was found. The observations establish guidelines for adjusting the deposition parameters to achieve the desired NbN{sub x} film morphology and phase.

  15. Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Chu, T.L. (University of South Florida, Tampa, FL (United States))

    1992-04-01

    This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75% or higher at 0. 44 {mu}m and a photovoltaic efficiency of 11.5% or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65% and a photovoltaic conversion efficiency of 5% and 8%, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and metal-organic chemical vapor deposition (MOCVD) technique, (2) depositing CdTe films by close-spaced sublimation (CSS) and MOCVD techniques, (3) preparing and evaluating thin film CdTe solar cells, and (4) preparing and characterizing thin film ZnTe, CD{sub 1-x}Zn{sub 1-x}Te, and Hg{sub 1-x}Zn{sub x}Te solar cells. The deposition of CdS films from aqueous solutions was investigated in detail, and their crystallographic, optical, and electrical properties were characterized. CdTe films were deposited from DMCd and DIPTe at 400{degrees}C using TEGa and AsH{sub 3} as dopants. CdTe films deposited by CSS had significantly better microstructures than those deposited by MOCVD. Deep energy states in CdTe films deposited by CSS and MOCVD were investigated. Thin films of ZnTe, Cd{sub 1- x}Zn{sub x}Te, and Hg{sub 1-x}Zn{sub x}Te were deposited by MOCVD, and their crystallographic, optical, and electrical properties were characterized. 67 refs.

  16. Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells

    Science.gov (United States)

    Chu, T. L.

    1992-04-01

    This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75 percent or higher at 0.44 microns and a photovoltaic efficiency of 11.5 percent or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65 percent and a photovoltaic conversion efficiency of 5 percent and 8 percent, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and metal-organic chemical vapor deposition (MOCVD) technique, (2) depositing CdTe films by close-spaced sublimation (CSS) and MOCVD techniques, (3) preparing and evaluating thin film CdTe solar cells, and (4) preparing and characterizing thin film ZnTe, CD(1-x)Zn(1-x)Te, and Hg(1-x)Zn(x)Te solar cells. The deposition of CdS films from aqueous solutions was investigated in detail, and their crystallographic, optical, and electrical properties were characterized. CdTe films were deposited from DMCd and DIPTe at 400 C using TEGa and AsH3 as dopants. CdTe films deposited by CSS had significantly better microstructures than those deposited by MOCVD. Deep energy states in CdTe films deposited by CSS and MOCVD were investigated. Thin films of ZnTe, Cd(1-x)Zn(x)Te, and Hg(1-x)Zn(x)Te were deposited by MOCVD, and their crystallographic, optical, and electrical properties were characterized.

  17. Epitaxial yttrium iron garnet films grown by pulsed laser deposition

    Science.gov (United States)

    Dorsey, P. C.; Bushnell, S. E.; Seed, R. G.; Vittoria, C.

    1993-07-01

    Epitaxial Y3Fe5O12 (YIG) films have been grown by the pulsed laser deposition (PLD) technique on (111) gadolinium gallium garnet substrates. The effect of substrate temperature and oxygen partial pressure on the structure, composition, and magnetic properties of the films was investigated and compared to liquid phase epitaxy YIG films. The results demonstrated that epitaxial YIG films could be prepared under a wide range of deposition conditions, but narrow linewidth (ΔH≂1 Oe) films were producible only at low oxygen partial pressures (O2temperatures (Ts≳800 °C). Since the linewidth of single-crystal YIG is dominated by surface and volume defects and/or impurities, the narrow linewidth indicated that PLD is a viable technique for producing high-quality ferrite films for microwave device applications. In addition, under all deposition conditions (50-1000 mTorr and 700-850 °C) there is a uniaxial axis perpendicular to the film plane. However, at low oxygen pressure the uniaxial anisotropy energy constant Ku is negative while at high oxygen pressure Ku is positive.

  18. CdS films deposited by chemical bath under rotation

    Energy Technology Data Exchange (ETDEWEB)

    Oliva-Aviles, A.I., E-mail: aoliva@mda.cinvestav.mx [Centro de Investigacion y de Estudios Avanzados Unidad Merida, Departamento de Fisica Aplicada. A.P. 73-Cordemex, 97310 Merida, Yucatan (Mexico); Patino, R.; Oliva, A.I. [Centro de Investigacion y de Estudios Avanzados Unidad Merida, Departamento de Fisica Aplicada. A.P. 73-Cordemex, 97310 Merida, Yucatan (Mexico)

    2010-08-01

    Cadmium sulfide (CdS) films were deposited on rotating substrates by the chemical bath technique. The effects of the rotation speed on the morphological, optical, and structural properties of the films were discussed. A rotating substrate-holder was fabricated such that substrates can be taken out from the bath during the deposition. CdS films were deposited at different deposition times (10, 20, 30, 40 and 50 min) onto Corning glass substrates at different rotation velocities (150, 300, 450, and 600 rpm) during chemical deposition. The chemical bath was composed by CdCl{sub 2}, KOH, NH{sub 4}NO{sub 3} and CS(NH{sub 2}){sub 2} as chemical reagents and heated at 75 deg. C. The results show no critical effects on the band gap energy and the surface roughness of the CdS films when the rotation speed changes. However, a linear increase on the deposition rate with the rotation energy was observed, meanwhile the stoichiometry was strongly affected by the rotation speed, resulting a better 1:1 Cd/S ratio as speed increases. Rotation effects may be of interest in industrial production of CdTe/CdS solar cells.

  19. Deposition of Cadmium Sulphide Thin Films by Photochemical Deposition and Characterization

    Directory of Open Access Journals (Sweden)

    H.L. Pushpalatha

    2015-03-01

    Full Text Available Deposition of cadmium sulphide (CdS thin films on glass substrates in acidic medium by photochemical deposition (PCD and studies by several characterizations are presented. The structural characterization of the thin films was carried out by XRD. The elemental composition of the thin films was carried out by EDAX. The optical properties have been studied in the wavelength range 200-900 nm and the optical transition has been found to be direct and allowed. The morphological properties are studied by AFM and electrical properties are studied by four probe technique.

  20. Control of crystallite size in diamond film chemical vapor deposition

    Science.gov (United States)

    Moran, Mark B.; Johnson, Linda F.; Klemm, Karl A.

    1992-12-01

    In depositing an adhering, continuous, polycrystalline diamond film of optical or semiconductor quality on a substrate, as by forming on the substrate a layer of a refractory nitride interlayer and depositing diamond on the interlayer without mechanical treatment or seeding of the substrate or the interlayer, the substrate is heated in a vacuum chamber containing a microwave activated mixture of hydrogen and a gas including carbon, and the size of deposited diamond crystallites and their rate of deposition selectively varied by a bias voltage applied to the substrate.

  1. [The impact of ZnS/CdS composite window layer on the quantun efficiency of CdTe solar cell in short wavelength].

    Science.gov (United States)

    Zhang, Li-xiang; Feng, Liang-huan; Wang, Wen-wu; Xu, Hang; Wu, Li-li; Zhang, Jing-quan; Li, Wei; Zeng, Guang-gen

    2015-02-01

    ZnS/CdS composite window layer was prepared by magnetron sputtering method and then applied to CdTe solar cell. The morphology and structure of films were measured. The data of I-V in light and the quantum efficiency of CdTe solar cells with different window layers were also measured. The effect of ZnS films prepared in different conditions on the performance of CdTe solar cells was researched. The effects of both CdS thickness and ZnS/CdS composite layer on the transmission in short wavelength were studied. Particularly, the quantum efficiency of CdTe solar cells with ZnS/CdS window layer was measured. The results show as follows. With the thickness of CdS window layer reducing from 100 to 50 nm, the transmission increase 18.3% averagely in short wavelength and the quantum efficiency of CdTe solar cells increase 27.6% averagely. The grain size of ZnS prepared in 250 degrees C is smaller than prepared at room temperature. The performance of CdTe solar cells with ZnS/CdS window layer is much better if ZnS deposited at 250 degrees C. This indicates grain size has some effect on the electron transportation. When the CdS holds the same thickness, the transmission of ZnS/CdS window layer was improved about 2% in short wavelength compared with CdS window layer. The quantum efficiency of CdTe solar cells with ZnS/CdS window layer was also improved about 2% in short wavelength compared with that based on CdS window layer. These indicate ZnS/CdS composite window layer can increase the photon transmission in short wavelength so that more photons can be absorbed by the absorbent layer of CdTe solar cells.

  2. Aspects of thin film deposition on granulates by physical vapor deposition

    Science.gov (United States)

    Eder, Andreas; Schmid, Gerwin H. S.; Mahr, Harald; Eisenmenger-Sittner, Christoph

    2016-11-01

    Thin film and coating technology has entered fields which may show significant deviations from classical coating applications where films are deposited on plane, sometimes large substrates. Often surfaces of small and irregularly shaped bodies have to be improved in respect to electrical, thermal or mechanical properties. Film deposition and characterization on such small substrates is not a trivial task. This specially holds for methods based on Physical Vapor Deposition (PVD) processes such as sputter deposition and its ion- and plasma assisted varieties. Due to their line of sight nature a key issue for homogenous films is efficient intermixing. If this problem is mastered, another task is the prediction and determination of the film thickness on single particles as well as on large scale ensembles thereof. In this work a mechanism capable of uniformly coating up to 1000 cm3 of granulate with particle sizes ranging from approx. 10 μm to 150 μm by magnetron sputtering is thoroughly described. A method for predicting the average film thickness on the particles is presented and tested for several differently shaped objects like microspheres, irregular grains of sinter powder or micro diamonds. For assessing the film thickness on single particles as well as on particle ensembles several complementary methods based on optics, X-ray analysis and gravimetry are employed. Their respective merits and limitations are discussed. Finally an outlook on adapting the described technology for surface modification by plasma based reactive and non-reactive processes is given.

  3. Deposition of Cu seed layer film by supercritical fluid deposition for advanced interconnects

    Institute of Scientific and Technical Information of China (English)

    Zhao Bin; Zhao Ming-Tao; Zhang Yan-Fei; Yang Jun-He

    2013-01-01

    The deposition of a Cu seed layer film is investigated by supercritical fluid deposition (SCFD) using H2 as a reducing agent for Bis(2,2,6,6-tetramethyl-3,5-heptanedionato) copper in supercritical CO2 (scCO2).The effects of deposition temperature,precursor,and H2 concentration are investigated to optimize Cu deposition.Continuous metallic Cu films are deposited on Ru substrates at 190 ℃ when a 0.002 mol/L Cu precursor is introduced with 0.75 mol/L H2.A Cu precursor concentration higher than 0.002 mol/L is found to have negative effects on the surface qualities of Cu films.For a H2concentration above 0.56 mol/L,the root-mean-square (RMS) roughness of a Cu film decreases as the H2 concentration increases.Finally,a 20-nm thick Cu film with a smooth surface,which is required as a seed layer in advanced interconnects,is successfully deposited at a high H2 concentration (0.75 mol/L).

  4. Annealing effects on the chemical deposited CdS films and the electrical properties of CdS/CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Han, Junfeng [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Liao, Cheng, E-mail: Cliao@pku.edu.cn [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Jiang, Tao [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Fu, Ganhua; Krishnakumar, V.; Spanheimer, C.; Haindl, G. [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Zhao, Kui [State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871 (China); Klein, A.; Jaegermann, W. [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany)

    2011-02-15

    Graphical abstract: From XPS core level spectras, compared with as-depositing CdS (sample A), the Fermi level is shifting closer to the conduction band after annealing treatment in the oxygen (sample B) while it is shifting closer to the valence band after annealing treatment in the argon-hydrogen (sample C). That might be the main reason of the different performance of the final devices. The open circuit voltage of the CdS/CdTe solar cell increases when the CBD CdS is annealed with oxygen, while the performance of the solar cell decreases when the CBD CdS is annealed with argon-hydrogen. Research highlights: {yields} Two different methods (oxidation and reduction) were used to anneal CdS films for CdTe solar cells. {yields} Electrical properties were analyzed by XPS (Fermi levels of CdS films). {yields} Annealing treatment in oxidation atmosphere could shift Fermi level of CdS film to higher position and consequently improve the CdS/CdTe junction and performance of solar cells. -- Abstract: CdS layers grown by chemical bath deposition (CBD) are annealed in the oxygen and argon-hydrogen atmosphere respectively. It has been found that the open circuit voltage of the CdS/CdTe solar cell increases when the CBD CdS is annealed with oxygen before the deposition of CdTe by close spaced sublimation (CSS), while the performance of the solar cell decreases when the CBD CdS is annealed with argon-hydrogen. Electronic properties of the CdS films are investigated using X-ray photo-electron spectroscopy (XPS), which indicates that the Fermi level is shifting closer to the conduction band after annealing in the oxygen and consequently a higher open circuit voltage of the solar cell can be obtained.

  5. Ultraviolet laser deposition of graphene thin films without catalytic layers

    KAUST Repository

    Sarath Kumar, S. R.

    2013-01-09

    In this letter, the formation of nanostructured graphene by ultraviolet laser ablation of a highly ordered pyrolytic graphite target under optimized conditions is demonstrated, without a catalytic layer, and a model for the growth process is proposed. Previously, graphene film deposition by low-energy laser (2.3 eV) was explained by photo-thermal models, which implied that graphene films cannot be deposited by laser energies higher than the C-C bond energy in highly ordered pyrolytic graphite (3.7 eV). Here, we show that nanostructured graphene films can in fact be deposited using ultraviolet laser (5 eV) directly over different substrates, without a catalytic layer. The formation of graphene is explained by bond-breaking assisted by photoelectronic excitation leading to formation of carbon clusters at the target and annealing out of defects at the substrate.

  6. Shallow bath chemical deposition of CdS thin film

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Y.S. [Department of Molecule Science and Engineering, National Taipei University of Science and Technology, Taipei, 10617, Taiwan (China); Choubey, R.K. [Department of Applied Physics, Birla Institute of Technology, Mesra, Ranchi, 835 215 (India); Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan (China); Yu, W.C. [Department of Molecule Science and Engineering, National Taipei University of Science and Technology, Taipei, 10617, Taiwan (China); Hsu, W.T. [Green Energy and Environmental Research Laboratory, Industrial Technology Research Institute, Hsin-Chu, Taiwan (China); Lan, C.W., E-mail: cwlan@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei, 10617, Taiwan (China)

    2011-10-31

    Cadmium sulfide thin film was grown by shallow chemical bath deposition technique. This technique used a highly conducted hot plate to heat the substrate, while using a shallow bath for higher thermal gradients. As a result, large area uniformity could be achieved and the homogeneous nucleation was suppressed. More importantly, the solution used was greatly reduced, which is crucial for cost reduction in practice. The effects of temperature and shaking on the growth kinetics and film properties were investigated. The reaction activation energy was obtained to be 0.84 eV, and was not affected much by shaking indicating that the deposition is essentially reaction controlled. Furthermore, the films deposited at low or high temperature conditions had better photoconductivity.

  7. Cobalt Xanthate Thin Film with Chemical Bath Deposition

    Directory of Open Access Journals (Sweden)

    İ. A. Kariper

    2013-01-01

    Full Text Available Cobalt xanthate thin films (CXTFs were successfully deposited by chemical bath deposition, onto amorphous glass substrates, as well as on p- and n-silicon, indium tin oxide, and poly(methyl methacrylate. The structure of the films was analyzed by far-infrared spectrum (FIR, mid-infrared (MIR spectrum, nuclear magnetic resonance (NMR, and scanning electron microscopy (SEM. These films were investigated from their structural, optical, and electrical properties point of view. Electrical properties were measured using four-point method, whereas optical properties were investigated via UV-VIS spectroscopic technique. Uniform distribution of grains was clearly observed from the photographs taken by scanning electron microscope (SEM. The transmittance was about 70–80% (4 hours, 50°C. The optical band gap of the CXTF was graphically estimated to be 3.99–4.02 eV. The resistivity of the films was calculated as 22.47–75.91 Ω·cm on commercial glass depending on film thickness and 44.90–73.10 Ω ·cm on the other substrates. It has been observed that the relative resistivity changed with film thickness. The MIR and FIR spectra of the films were in agreement with the literature analogues. The expected peaks of cobalt xanthate were observed in NMR analysis on glass. The films were dipped in chloroform as organic solvent and were analyzed by NMR.

  8. Characterization of Thin Films Deposited with Precursor Ferrocene by Plasma Enhanced Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    YAO Kailun; ZHENG Jianwan; LIU Zuli; JIA Lihui

    2007-01-01

    In this paper,the characterization of thin films,deposited with the precursor ferrocene(FcH)by the plasma enhanced chemical vapour deposition(PECVD)technique,was investigated.The films were measured by Scanning Electronic Microscopy(SEM),Atomic Force Microscopy(AFM),Electron Spectroscopy for Chemical Analysis(ESCA),and superconducting Quantum Interference Device(SQUID).It was observed that the film's layer is homogeneous in thickness and has a dense morphology without cracks.The surface roughness is about 36 nm.From the results of ESCA,it can be inferred that the film mainly contains the compound FeOOH,and carbon is combined with oxygen in different forms under different supply-powers.The hysteresis loops indicate that the film is of soft magnetism.

  9. Microwave annealing effects on ZnO films deposited by atomic layer deposition

    Institute of Scientific and Technical Information of China (English)

    Zhao Shirui; Dong Yabin; Yu Mingyan; Guo Xiaolong; Xu Xinwei; Jing Yupeng; Xia Yang

    2014-01-01

    Zinc oxide thin films deposited on glass substrate at 150 ℃ by atomic layer deposition were annealed by the microwave method at temperatures below 500 ℃.The microwave annealing effects on the structural and luminescent properties of ZnO films have been investigated by X-ray diffraction and photoluminescence.The results show that the MWA process can increase the crystal quality of ZnO thin films with a lower annealing temperature than RTA and relatively decrease the green luminescence of ZnO films.The observed changes have demonstrated that MWA is a viable technique for improving the crystalline quality of ZnO thin film on glass.

  10. Recent Progress in Nanoelectrical Characterizations of CdTe and Cu(In,Ga)Se2

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Chun-Sheng; To, Bobby; Glynn, Stephen; Mahabaduge, Hasitha; Barnes, Teresa; Al-Jassim, Mowafak M.

    2016-11-21

    We report two recent nanoelectrical characterizations of CdTe and Cu(In, Ga)Se2 (CIGS) thin-film solar cells by developing atomic force microscopy-based nanoelectrical probes. Charges trapped at defects at the CdS/CdTe interface were probed by Kelvin probe force microscopy (KPFM) potential mapping and by ion-milling the CdTe superstrate device in a bevel glancing angle of ~0.5 degrees. The results show randomly distributed donor-like defects at the interface. The effect of K post-deposition treatment on the near-surface region of the CIGS film was studied by KPFM potential and scanning spreading resistance microscopy (SSRM) resistivity mapping, which shows passivation of grain-boundary potential and improvement of resistivity uniformity by the K treatment.

  11. The effects of high temperature processing on the structural and optical properties of oxygenated CdS window layers in CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Paudel, Naba R.; Grice, Corey R.; Xiao, Chuanxiao; Yan, Yanfa [Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization, The University of Toledo, Toledo, Ohio 43606 (United States)

    2014-07-28

    High efficiency CdTe solar cells typically use oxygenated CdS (CdS:O) window layers. We synthesize CdS:O window layers at room temperature (RT) and 270 °C using reactive sputtering. The band gaps of CdS:O layers deposited at RT increase when O{sub 2}/(O{sub 2} + Ar) ratios in the deposition chamber increase. On the other hand, the band gaps of CdS:O layers deposited at 270 °C decrease as the O{sub 2}/(O{sub 2} + Ar) ratios increase. Interestingly, however, our high temperature closed-space sublimation (CSS) processed CdTe solar cells using CdS:O window layers deposited at RT and 270 °C exhibit very similar cell performance, including similar short-circuit current densities. To understand the underlying reasons, CdS:O thin films deposited at RT and 270 °C are annealed at temperatures that simulate the CSS process of CdTe deposition. X-ray diffraction, atomic force microscopy, and UV-visible light absorption spectroscopy characterization of the annealed films reveals that the CdS:O films deposited at RT undergo grain regrowth and/or crystallization and exhibit reduced band gaps after the annealing. Our results suggest that CdS:O thin films deposited at RT and 270 °C should exhibit similar optical properties after the deposition of CdTe layers, explaining the similar cell performance.

  12. CdS: Characterization and recent advances in CdTe solar cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Ferekides, C.; Marinskiy, D.; Morel, D.L. [Univ. of South Florida, FL (United States)

    1997-12-31

    Cadmium sulfide (CdS) films deposited by chemical bath deposition (CBD) have been used for the fabrication of high efficiency CdTe and CuIn{sub 1{minus}x}Ga{sub x}Se{sub 2} thin film solar cells. An attractive alternative deposition technology with manufacturing advantages over the CBD is the close spaced sublimation (CSS). In this work CdTe/CdS solar cells prepared entirely by the CSS process exhibited 15.0% efficiencies under global AM1.5 conditions as verified at the National Renewable Energy Laboratory. This paper reports on studies carried out on as deposited and heat treated CSS CdS films and all CSS CdTe/CdS solar cells using photoluminescence, x-ray diffraction, and I-V-T measurements.

  13. Spray pyrolysis deposition of indium sulphide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Otto, K.; Katerski, A.; Mere, A.; Volobujeva, O.; Krunks, M., E-mail: malle@staff.ttu.e

    2011-03-01

    In{sub 2}S{sub 3} thin films were grown by the chemical spray pyrolysis (CSP) method using the pneumatic spray set-up and compressed air as a carrier gas. Aqueous solutions containing InCl{sub 3} and SC(NH{sub 2}){sub 2} at a molar ratio of In/S = 1/3 and 1/6 were deposited onto preheated glass sheets at substrate temperatures T{sub s} = 205-410 {sup o}C. The obtained films were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM,) optical transmission spectra, X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS). According to XRD, thin films deposited at T{sub s} = 205-365 {sup o}C were composed of the (0 0 12) orientated tetragonal {beta}-In{sub 2}S{sub 3} phase independent of the In/S ratio in the spray solution. Depositions performed at T{sub s} = 410 {sup o}C led to the formation of the In{sub 2}O{sub 3} phase, preferably when the 1/3 solution was sprayed. Post-deposition annealing in air indicated that oxidation of the sulphide phase has a minor role in the formation of In{sub 2}O{sub 3} at temperatures up to 450 {sup o}C. In{sub 2}S{sub 3} films grown at T{sub s} below 365 {sup o}C exhibited transparency over 70% in the visible spectral region and E{sub g} of 2.90-2.96 eV for direct and 2.15-2.30 eV for indirect transitions, respectively. Film thickness and chlorine content decreased with increasing deposition temperatures. The XPS study revealed that the In/S ratio in the spray solution had a significant influence on the content of oxygen (Me-O, BE = 530.0 eV) in the In{sub 2}S{sub 3} films deposited in the temperature range of 205-365 {sup o}C. Both XPS and EDS studies confirmed that oxygen content in the films deposited using the solution with the In/S ratio of 1/6 was substantially lower than in the films deposited with the In/S ratio of 1/3.

  14. Glancing angle deposition of thin films engineering the nanoscale

    CERN Document Server

    Hawkeye, Matthew M; Brett, Michael J

    2014-01-01

    This book provides a highly practical treatment of GLAD technology, gathering existing procedures, methodologies, and experimental designs into a single, cohesive volume which will be useful both as a ready reference for those in the field and as a definitive guide for those entering it. It covers: History and development of GLAD techniquesProperties and Characterization of GLAD fabricated filmsDesign and engineering of optical GLAD films including fabrication and testingPost-deposition processing and integrationDeposition systems for GLAD fabrication Also includes a patent survey of relevant literature and a survey of GLAD's wide range of material properties and diverse applications.

  15. Degradation and capacitance: voltage hysteresis in CdTe devices

    Science.gov (United States)

    Albin, D. S.; Dhere, R. G.; Glynn, S. C.; del Cueto, J. A.; Metzger, W. K.

    2009-08-01

    CdS/CdTe photovoltaic solar cells were made on two different transparent conducting oxide (TCO) structures in order to identify differences in fabrication, performance, and reliability. In one set of cells, chemical vapor deposition (CVD) was used to deposit a bi-layer TCO on Corning 7059 borosilicate glass consisting of a F-doped, conductive tin-oxide (cSnO2) layer capped by an insulating (undoped), buffer (iSnO2) layer. In the other set, a more advanced bi-layer structure consisting of sputtered cadmium stannate (Cd2SnO4; CTO) as the conducting layer and zinc stannate (Zn2SnO4; ZTO) as the buffer layer was used. CTO/ZTO substrates yielded higher performance devices however performance uniformity was worse due to possible strain effects associated with TCO layer fabrication. Cells using the SnO2-based structure were only slightly lower in performance, but exhibited considerably greater performance uniformity. When subjected to accelerated lifetime testing (ALT) at 85 - 100 °C under 1-sun illumination and open-circuit bias, more degradation was observed in CdTe cells deposited on the CTO/ZTO substrates. Considerable C-V hysteresis, defined as the depletion width difference between reverse and forward direction scans, was observed in all Cu-doped CdTe cells. These same effects can also be observed in thin-film modules. Hysteresis was observed to increase with increasing stress and degradation. The mechanism for hysteresis is discussed in terms of both an ionic-drift model and one involving majority carrier emission in the space-charge region (SCR). The increased generation of hysteresis observed in CdTe cells deposited on CTO/ZTO substrates suggests potential decomposition of these latter oxides when subjected to stress testing.

  16. Study of indium tin oxide thin films deposited on acrylics substrates by Ion beam assisted deposition technique

    OpenAIRE

    Meng Lijian; Liang Erjun; Gao Jinsong; Teixeira, Vasco M. P.; Santos, M. P. dos

    2009-01-01

    Indium tin oxide (ITO) thin films have been deposited onto acrylics (PMMA) substrates by ion beam assisted deposition technique at different oxygen flows. The structural, optical and electrical properties of the deposited films have been characterized by X-ray diffraction, transmittance, FTIR, ellipometry and Hall effect measurements. The optical constants of the deposited films have been calculated by fitting the ellipsometric spectra. The effects of the oxygen flow on the properties of the ...

  17. Fabrication and characterization of vacuum deposited fluorescein thin films

    Energy Technology Data Exchange (ETDEWEB)

    Jalkanen, Pasi, E-mail: pasi.jalkanen@gmail.co [University of Jyvaeskylae, Department of Physics, Nanoscience center (NSC), P.O. Box 35, FI-40014 Jyvaeskylae (Finland); Kulju, Sampo, E-mail: sampo.j.kulju@jyu.f [University of Jyvaeskylae, Department of Physics, Nanoscience center (NSC), P.O. Box 35, FI-40014 Jyvaeskylae (Finland); Arutyunov, Konstantin, E-mail: konstantin.arutyunov@jyu.f [University of Jyvaeskylae, Department of Physics, Nanoscience center (NSC), P.O. Box 35, FI-40014 Jyvaeskylae (Finland); Antila, Liisa, E-mail: liisa.j.antila@jyu.f [University of Jyvaeskylae, Department of Chemistry, Nanoscience center (NSC) P.O. Box 35, FI-40014 Jyvaeskylae (Finland); Myllyperkioe, Pasi, E-mail: pasi.myllyperkio@jyu.f [University of Jyvaeskylae, Department of Chemistry, Nanoscience center (NSC) P.O. Box 35, FI-40014 Jyvaeskylae (Finland); Ihalainen, Teemu, E-mail: teemu.o.ihalainen@jyu.f [University of Jyvaeskylae, Department of Biology, Nanoscience center (NSC), P.O. Box 35, FI-40014 Jyvaeskylae (Finland); Kaeaeriaeinen, Tommi, E-mail: tommi.kaariainen@lut.f [Lappeenranta University of Technology, ASTRal, P.O. Box 181, FI-50101 Mikkeli (Finland); Kaeaeriaeinen, Marja-Leena, E-mail: marja-leena.kaariainen@lut.f [Lappeenranta University of Technology, ASTRal, P.O. Box 181, FI-50101 Mikkeli (Finland); Korppi-Tommola, Jouko, E-mail: jouko.korppi-tommola@jyu.f [University of Jyvaeskylae, Department of Biology, Nanoscience center (NSC), P.O. Box 35, FI-40014 Jyvaeskylae (Finland)

    2011-03-31

    Simple vacuum evaporation technique for deposition of dyes on various solid surfaces has been developed. The method is compatible with conventional solvent-free nanofabrication processing enabling fabrication of nanoscale optoelectronic devices. Thin films of fluorescein were deposited on glass, fluorine-tin-oxide (FTO) coated glass with and without atomically layer deposited (ALD) nanocrystalline 20 nm thick anatase TiO{sub 2} coating. Surface topology, absorption and emission spectra of the films depend on their thickness and the material of supporting substrate. On a smooth glass surface the dye initially forms islands before merging into a uniform layer after 5 to 10 monolayers. On FTO covered glass the absorption spectra are similar to fluorescein solution in ethanol. Absorption spectra on ALD-TiO{sub 2} is red shifted compared to the film deposited on bare FTO. The corresponding emission spectra at {lambda} = 458 nm excitation show various thickness and substrate dependent features, while the emission of films deposited on TiO{sub 2} is quenched due to the effective electron transfer to the semiconductor conduction band.

  18. CdTe Photovoltaic Devices for Solar Cell Applications

    Science.gov (United States)

    2011-12-01

    July 28, 2011 14. ABSTRACT Cadmium telluride ( CdTe ) has been recognized as a promising photovoltaic material for thin - film solar cells because of...mail.mil Phone: 301 394 0963 ABSTRACT Cadmium telluride ( CdTe ) has been recognized as a promising photovoltaic material for thin - film ...absorption coefficient allows films as thin as 2 μm to absorb more than 98% of the above-bandgap radiation. Cells with efficiencies near 17% have been

  19. The Effect of Deposition Time on Textured Magnesium Diboride Thick Films Fabricated by Electrophoretic Deposition

    Directory of Open Access Journals (Sweden)

    W. G. Mutia

    2004-12-01

    Full Text Available MgB2 powders suspended in ethanol were electrophoretically deposited on high-purity molybdenum substrates having dimensions of 1 x 0.3 x 0.01 cm. The said substrate was set as the cathode and was placed 0.5 cm away from a graphite rod anode. A current density of ~0.02 mA/cm2 and a voltage of 600 V were applied. The effect of deposition time was studied by varying it as follows: 15 s, 30 s, 1 min, and 2 min. Heat treatment at 950 oC for 3 h was done after deposition. MgB2 thick films were successfully fabricated for the deposition carried out for 2 min. Deposition times less than 2 min resulted in insufficient deposited powder; hence formation of MgB2 was not facilitated. Films deposited at 15 and 30 s have good surface characteristics, wherein no microcracks were present. X-ray diffraction and surface image analysis reveal that the deposited films have a preferred orientation along the (10l direction.

  20. Morphological Study Of Palladium Thin Films Deposited By Sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Salcedo, K L; Rodriguez, C A [Grupo Plasma Laser y Aplicaciones, Ingenieria Fisica, Universidad Tecnologica de Pereira (Colombia); Perez, F A [WNANO, West Virginia University (United States); Riascos, H [Grupo Plasma Laser y Aplicaciones, Departamento de Fisica, Universidad Tecnologica de Pereira (Colombia)

    2011-01-01

    This paper presents a morphological analysis of thin films of palladium (Pd) deposited on a substrate of sapphire (Al{sub 2}O{sub 3}) at a constant pressure of 3.5 mbar at different substrate temperatures (473 K, 523 K and 573 K). The films were morphologically characterized by means of an Atomic Force Microscopy (AFM); finding a relation between the roughness and the temperature. A morphological analysis of the samples through AFM was carried out and the roughness was measured by simulating the X-ray reflectivity curve using GenX software. A direct relation between the experimental and simulation data of the Palladium thin films was found.

  1. Alternating deposition films of a polymer and dendrimers bearing diphenylanthracene

    Institute of Scientific and Technical Information of China (English)

    SUN Jing; WANG Liyan; GAO Jian; YU Xi; WANG Zhiqiang

    2005-01-01

    Two generations of carboxyl-terminated poly (aryl ether) dendrimers bearing 9,10-diphenylanthracene cores are designed and synthesized. Alternating deposition of two dendrimers and poly(4-vinylpyridine) is studied with UV-Vis spectroscopy, FT-IR spectroscopy and atomic force microscopy. Experimental results indicate that this method to introduce chromophore into multilayer film can effectively prevent desorption of dye molecule. Moreover, it is found that dendrimer can inhibit the aggregation of fluorophore in film using fluorescence spectroscopy. Increase of dendrimer's generation can enhance fluorescence intensity of each fluorophore. This provides a new approach to design luminescent thin film.

  2. Oxide films: low-temperature deposition and crystallization

    Science.gov (United States)

    Park, Sangmoon; Herman, Gregory S.; Keszler, Douglas A.

    2003-10-01

    Thin films of CeO 2 and (Ce,Sm)O 2 have been prepared by using the SILAR method of deposition in conjunction with hydrothermal and high-temperature annealing. Low-temperature, low-pressure hydrothermal annealing of amorphous Mn:Zn 2GeO 4 films has lead to the growth of grains having edge lengths near 1 μm. Thick films of crystalline Zn 2SiO 4 exhibiting limited cracking have been prepared by a doctor-blade method also in conjunction with hydrothermal dehydration and annealing.

  3. Impact toughness of tungsten films deposited on martensite stainless steel

    Institute of Scientific and Technical Information of China (English)

    HUANG Ning-kang; YANG Bin; WANG De-zhi

    2005-01-01

    Tungsten films were deposited on stainless steel Charpy specimens by magnetron sputtering followed by electron beam heat treatment. Charpy impact tests and scanning electron microscopy were used to investigate the ductile-brittle transition behavior of the specimens. With decreasing test temperature the fracture mode was transformed from ductile to brittle for both kinds of specimens with and without W films. The data of the crack initiation energy, crack propagation energy, impact absorbing energy, fracture time and deflection as well as the fracture morphologies at test temperature of -70 ℃ show that W films can improve the impact toughness of stainless steel.

  4. Cadmium Sulfide Thin Films Deposited onto MWCNT/Polysulfone Substrates by Chemical Bath Deposition

    Directory of Open Access Journals (Sweden)

    M. Moreno

    2016-01-01

    Full Text Available Cadmium sulfide (CdS thin films were deposited by chemical bath deposition (CBD onto polymeric composites with electric field-aligned multiwall carbon nanotubes (MWCNTs. MWCNT/polysulfone composites were prepared by dispersing low concentrations of MWCNTs within dissolved polysulfone (PSF. An alternating current electric field was “in situ” applied to align the MWCNTs within the dissolved polymer along the field direction until the solvent was evaporated. 80 μm thick solid MWCNT/PSF composites with an electrical conductivity 13 orders of magnitude higher than the conductivity of the neat PSF were obtained. The MWCNT/PSF composites were subsequently used as flexible substrates for the deposition of CdS thin films by CBD. Transparent and adherent CdS thin films with an average thickness of 475 nm were obtained. The values of the energy band gap, average grain size, rms roughness, crystalline structure, and preferential orientation of the CdS films deposited onto the polymeric substrate were very similar to the corresponding values of the CdS deposited onto glass (conventional substrate. These results show that the MWCNT/PSF composites with electric field-tailored MWCNTs represent a suitable option to be used as flexible conducting substrate for CdS thin films, which represents an important step towards the developing of flexible systems for photovoltaic applications.

  5. Deposition and characterisation of epitaxial oxide thin films for SOFCs

    KAUST Repository

    Santiso, José

    2010-10-24

    This paper reviews the recent advances in the use of thin films, mostly epitaxial, for fundamental studies of materials for solid oxide fuel cell (SOFC) applications. These studies include the influence of film microstructure, crystal orientation and strain in oxide ionic conducting materials used as electrolytes, such as fluorites, and in mixed ionic and electronic conducting materials used as electrodes, typically oxides with perovskite or perovskite-related layered structures. The recent effort towards the enhancement of the electrochemical performance of SOFC materials through the deposition of artificial film heterostructures is also presented. These thin films have been engineered at a nanoscale level, such as the case of epitaxial multilayers or nanocomposite cermet materials. The recent progress in the implementation of thin films in SOFC devices is also reported. © 2010 Springer-Verlag.

  6. Coaxial carbon plasma gun deposition of amorphous carbon films

    Science.gov (United States)

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

    1984-01-01

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

  7. Polyelectrolyte Coacervates Deposited as High Gas Barrier Thin Films.

    Science.gov (United States)

    Haile, Merid; Sarwar, Owais; Henderson, Robert; Smith, Ryan; Grunlan, Jaime C

    2017-01-01

    Multilayer coatings consisting of oppositely charged polyelectrolytes have proven to be extraordinarily effective oxygen barriers but require many processing steps to fabricate. In an effort to prepare high oxygen barrier thin films more quickly, a polyelectrolyte complex coacervate composed of polyethylenimine and polyacrylic acid is prepared. The coacervate fluid is applied as a thin film using a rod coating process. With humidity and thermal post-treatment, a 2 µm thin film reduces the oxygen transmission rate of 0.127 mm poly(ethylene terephthalate) by two orders of magnitude, rivalling conventional oxygen barrier technologies. These films are fabricated in ambient conditions using low-cost, water-based solutions, providing a tremendous opportunity for single-step deposition of polymeric high barrier thin films.

  8. Deposition of ZnO Films on Freestanding CVD Thick Diamond Films

    Institute of Scientific and Technical Information of China (English)

    SUN Jian; BAI Yi-Zhen; YANG Tian-Peng; XU Yi-Bin; WANG Xin-Sheng; DU Guo-Tong; WU Han-Hua

    2006-01-01

    @@ For ZnO/diamond structured surface acoustic wave (SAW) filters, performance is sensitively dependent on the quality of the ZnO films. In this paper, we prepare highly-oriented and fine grained polycrystalline ZnO thin films with excellent surface smoothness on the smooth nucleation surfaces of freestanding CVD diamond films by metal organic chemical vapour deposition (MOCVD). The properties of the ZnO films are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectrum. The influences of the deposition conditions on the quality of ZnO films are discussed briefly. ZnO/freestanding thick-diamond-film layered SAW devices with high response frequencies are expected to be developed.

  9. Environmentally stable sputter-deposited thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, D.J.

    1978-03-01

    Accelerated corrosion data are presented for the titanium-silver and chrome-gold thin film metallization systems presently used at Sandia Laboratories. Improvements in corrosion, hence reliability, as a result of interposing a thin intermediate layer of either platinum or palladium are shown. Potentiometric measurements showing the alteration of corrosion potential with the use of palladium for the titanium-silver system are also presented.

  10. CHEMICALLY DEPOSITED SILVER FILM USED AS A SERS-ACTIVE OVER COATING LAYER FOR POLYMER FILM

    Institute of Scientific and Technical Information of China (English)

    Xiao-ning Liu; Gi Xue; Yun Lu; Jun Zhang; Fen-ting Li; Chen-chen Xue; Stephen Z.D. Cheng

    2001-01-01

    When colloidal silver particles were chemically deposited onto polymer film as an over-coating layer, surfaceenhanced Raman scattering (SERS) spectra could be collected for the surface analysis. SERS measurements of liquid crystal film were successfully performed without disturbing the surface morphology.

  11. Fundamental Mechanisms of Roughening and Smoothing During Thin Film Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Headrick, Randall [Univ. of Vermont, Burlington, VT (United States)

    2016-03-18

    In this research program, we have explored the fundamental limits for thin film deposition in both crystalline and amorphous (i.e. non-crystalline) materials systems. For vacuum-based physical deposition processes such as sputter deposition, the background gas pressure of the inert gas (usually argon) used as the process gas has been found to be a key variable. Both a roughness transition and stress transition as a function of pressure have been linked to a common mechanism involving collisions of energetic particles from the deposition source with the process inert gas. As energetic particles collide with gas molecules in the deposition process they lose their energy rapidly if the pressure (and background gas density) is above a critical value. Both roughness and stress limit important properties of thin films for applications. In the area of epitaxial growth we have also discovered a related effect; there is a critical pressure below which highly crystalline layers grow in a layer-by-layer mode. This effect is also though to be due to energetic particle thermalization and scattering. Several other important effects such as the observation of coalescence dominated growth has been observed. This mode can be likened to the behavior of two-dimensional water droplets on the hood of a car during a rain storm; as the droplets grow and touch each other they tend to coalesce rapidly into new larger circular puddles, and this process proceeds exponentially as larger puddles overtake smaller ones and also merge with other large puddles. This discovery will enable more accurate simulations and modeling of epitaxial growth processes. We have also observed that epitaxial films undergo a roughening transition as a function of thickness, which is attributed to strain induced by the crystalline lattice mismatch with the substrate crystal. In addition, we have studied another physical deposition process called pulsed laser deposition. It differs from sputter deposition due to the

  12. Protection of elastomers with DLC film : deposition, characterization and performance

    NARCIS (Netherlands)

    Martinez Martinez, Diego

    2017-01-01

    Elastomers are materials which suffer from strong wear and cause high friction losses when subjected to dynamic contact, leading quite often to failure of the components in devices. In this Thesis, the protection of elastomers by the deposition of carbon-based films (DLC) is studied. To accomplish t

  13. Chemical Vapor Deposition of Aluminum Oxide Thin Films

    Science.gov (United States)

    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…

  14. Silicon Nitride Film Deposition by Photochemical Vapor Deposition Using an Argon Excimer Lamp

    Science.gov (United States)

    Maezono, Yoshinari; Toshikawa, Kiyohiko; Kurosawa, Kou; Amari, Kouichi; Ishimura, Sou; Katto, Masahito; Yokotani, Atsushi

    2007-06-01

    In this paper, we report the deposition of silicon nitride (SiNx) films for the production of semiconductor devices and flat panel displays, by chemical vapor deposition with vacuum ultraviolet excimer lamps (VUV-CVD) using SiH4 and NH3 as raw materials. An Ar2* excimer lamp (λ=126 nm, hν=9.8 eV) with a high photon energy was used to directly excite and dissociate SiH4 through a photochemical reaction. SiNx films were successfully formed at a low temperature of 100 °C with the Ar2* excimer lamp. Although the Si-rich films were obtained using an Ar2* lamp, they showed a quality almost similar to that of films obtained by conventional plasma-CVD at 400 °C.

  15. Low resistance polycrystalline diamond thin films deposited by hot filament chemical vapour deposition

    Indian Academy of Sciences (India)

    Mahtab Ullah; Ejaz Ahmed; Abdelbary Elhissi; Waqar Ahmed

    2014-05-01

    Polycrystalline diamond thin films with outgrowing diamond (OGD) grains were deposited onto silicon wafers using a hydrocarbon gas (CH4) highly diluted with H2 at low pressure in a hot filament chemical vapour deposition (HFCVD) reactor with a range of gas flow rates. X-ray diffraction (XRD) and SEM showed polycrystalline diamond structure with a random orientation. Polycrystalline diamond films with various textures were grown and (111) facets were dominant with sharp grain boundaries. Outgrowth was observed in flowerish character at high gas flow rates. Isolated single crystals with little openings appeared at various stages at low gas flow rates. Thus, changing gas flow rates had a beneficial influence on the grain size, growth rate and electrical resistivity. CVD diamond films gave an excellent performance for medium film thickness with relatively low electrical resistivity and making them potentially useful in many industrial applications.

  16. YBCO thin film evaporation on as-deposited silver film on MgO

    Science.gov (United States)

    Azoulay, J.

    1999-11-01

    YBa 2Cu 3O 7- δ (YBCO) thin film was evaporated on as-deposited Ag buffer layer on MgO substrate. A simple, inexpensive vacuum system equipped with one resistively heated source was used. The subsequent heat treatment was carried out under low oxygen partial pressure at a relatively low temperature and short dwelling time. The films thus obtained were characterized for electrical properties using DC four-probe electrical measurements and inspected for structural properties and chemical composition by scanning electron microscopy (SEM). It is shown that YBCO thin film can grow on as-deposited thin silver layer on MgO substrate.

  17. Enhanced performance of CdS/CdTe thin-film devices through temperature profiling techniques applied to close-spaced sublimation deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xiaonan Li; Sheldon, P.; Moutinho, H.; Matson, R. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    The authors describe a methodology developed and applied to the close-spaced sublimation technique for thin-film CdTe deposition. The developed temperature profiles consisted of three discrete temperature segments, which the authors called the nucleation, plugging, and annealing temperatures. They have demonstrated that these temperature profiles can be used to grow large-grain material, plug pinholes, and improve CdS/CdTe photovoltaic device performance by about 15%. The improved material and device properties have been obtained while maintaining deposition temperatures compatible with commercially available substrates. This temperature profiling technique can be easily applied to a manufacturing environment by adjusting the temperature as a function of substrate position instead of time.

  18. Structural and optical properties of tellurite thin film glasses deposited by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Martin, D.; Fernandez-Navarro, J.M. [Laser Processing Group, Instituto de Optica (CSIC), Serrano 121, 28006 Madrid (Spain); Gonzalo, J., E-mail: j.gonzalo@io.cfmac.csic.es [Laser Processing Group, Instituto de Optica (CSIC), Serrano 121, 28006 Madrid (Spain); Jose, G.; Jha, A. [Institute for Materials Research, University of Leeds, Clarendon Road, Leeds LS2 9JT (United Kingdom); Fierro, J.L.G. [Instituto de Catalisis y Petroleoquimica (CSIC), Marie Curie s/n, 28049 Cantoblanco (Spain); Domingo, C. [Instituto de Estructura de la Materia (CSIC), Serrano 121, 28006 Madrid (Spain); Garcia-Lopez, J. [Centro Nacional de Aceleradores, P. Tecnologico ' Cartuja 93' , 41092 Sevilla (Spain)

    2011-10-31

    Tellurite (TeO{sub 2}-TiO{sub 2}-Nb{sub 2}O{sub 5}) thin film glasses have been produced by pulsed laser deposition at room temperature at laser energy densities in the range of 0.8-1.5 J/cm{sup 2} and oxygen pressures in the range of 3-11 Pa. The oxygen concentration in the films increases with laser energy density to reach values very close to that of the bulk glass at 1.5 J/cm{sup 2}, while films prepared at 1.5 J/cm{sup 2} and pressures above 5 Pa show oxygen concentration in excess of 10% comparing to the glass. X-ray photoelectron spectroscopy shows the presence of elementary Te in films deposited at O{sub 2} pressures {<=} 5 Pa that is not detected at higher pressures, while analysis of Raman spectra of the samples suggests a progressive substitution of TeO{sub 3} trigonal pyramids by TeO{sub 4} trigonal bipyramids in the films when increasing their oxygen content. Spectroscopic ellipsometry analysis combined with Cauchy and effective medium modeling demonstrates the influence of these compositional and structural modifications on the optical response of the films. Since the oxygen content determines their optical response through the structural modifications induced in the films, those can be effectively controlled by tuning the deposition conditions, and films having large n (2.08) and reduced k (< 10{sup -4}) at 1.5 {mu}m have been produced using the optimum deposition conditions.

  19. Directed vapor deposition of lithium manganese oxide films

    Science.gov (United States)

    Jin, Sang-Wan

    Electron beam evaporation and sputtering techniques are used to fabricate multilayered thin film structures. However, these techniques suffer several drawbacks resulting from (i) the complex chemistries of the lithiated oxide layers used for the cathode and electrolyte, (ii) the need for precise microstructure control in systems with many metastable phases, and (iii) the low deposition rate and poor material utilization efficiency, which slows the application of this energy storage approach. This dissertation has investigated the use of a novel electron-beam directed vapor deposition (EB-DVD) method for the synthesis of thin film batteries. The dissertation focuses upon the cathode layer of a representative Li-ion thin film battery system and investigates in detail the deposition of lithium manganese oxide films. Many phases with offering various electrochemical performance exist in the Li-Mn-O system and the thesis also investigates the use of processing conditions to control the structure and composition of these cathode layers. In the EB-DVD approach, a high voltage electron beam is used to evaporate a source material in the throat of a nozzle that forms a coaxial transonic gas jet around the vapor. The gas jet entrains and transports the vapor to a substrate where the deposition occurs. Directed simulation of Monte Carlo (DSMC) methods indicated that the vapor plume could be matched to a substrate diameter, and the deposition rate (and vapor utilization efficiency) therefore controlled by adjusting the pressure ratio up and downstream of the nozzle opening in the deposition chamber, and by varying the gas jet density and speed. The highest deposition rates were obtained with a high pressure ratio and the gas jet density. These observations are found to be consistent with the experimental results. Deposition rates up to 16 nm/s could be achieved using the most effective gas entrainment conditions identified by DSMC calculation. This was about a factor of ten

  20. Dual ion beam deposition of carbon films with diamondlike properties

    Science.gov (United States)

    Mirtich, M. J.; Swec, D. M.; Angus, J. C.

    1984-01-01

    A single and dual ion beam system was used to generate amorphous carbon films with diamond like properties. A methane/argon mixture at a molar ratio of 0.28 was ionized in the low pressure discharge chamber of a 30-cm-diameter ion source. A second ion source, 8 cm in diameter was used to direct a beam of 600 eV Argon ions on the substrates (fused silica or silicon) while the deposition from the 30-cm ion source was taking place. Nuclear reaction and combustion analysis indicate H/C ratios for the films to be 1.00. This high value of H/C, it is felt, allowed the films to have good transmittance. The films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Although the measured density of the films was approximately 1.8 gm/cu cm, a value lower than diamond, the films exhibited other properties that were relatively close to diamond. These films were compared with diamondlike films generated by sputtering a graphite target.

  1. Effective conductivity of chemically deposited ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Robles, M. [Universidad Autonoma del Estado de Morelos (UAEM), Cuernavaca (Mexico). Fac. de Ciencias; Tagueena-Martinez, J. [IIM-UNAM, Temixco, Morelos (Mexico). Lab. de Energia Solar; Del Rio, J.A. [IIM-UNAM, Temixco, Morelos (Mexico). Lab. de Energia Solar

    1997-01-30

    Chemically deposited thin films have multiple applications. However, as a result of their complex structure, their physical properties are very difficult to predict. In this paper, we use an effective medium approach to model these heterogeneous systems. We extend Thorpe`s formula for the effective electrical conductivity of elliptical holes randomly distributed in a matrix to a system composed of conducting ellipses in a conducting matrix. This extension is used to calculate the effective electrical conductivity of polycrystalline chemically deposited ZnO thin films. We compare experimental results obtained by two different deposition methods: spray pyrolysis and successive ion layer adsorption and reaction (SILAR) reported here. We select the elliptical geometric parameters from microstructural data. Good agreement between the experimental measurements and our calculation is obtained. In addition, we present a new proof of the reciprocity theorem used to derive the theoretical relation. (orig.)

  2. Flame spray pyrolysis synthesis and aerosol deposition of nanoparticle films

    DEFF Research Database (Denmark)

    Tricoli, Antonio; Elmøe, Tobias Dokkedal

    2012-01-01

    (>100 nm) fractal‐like structures with low diffusivity. As a result, thermophoresis was confirmed as the dominant nanoparticle deposition mechanism down to small (≈40 K) temperature differences (ΔT) between the aerosol and the substrate surface. For moderate‐high ΔT (>120 K), thermal equilibrium......The assembly of nanoparticle films by flame spray pyrolysis (FSP) synthesis and deposition on temperature‐controlled substrates (323–723 K) was investigated for several application‐relevant conditions. An exemplary SnO2 nanoparticle aerosol was generated by FSP and its properties (e.g., particle...... size distribution), and deposition dynamics were studied in details aiming to a simple correlation between process settings and film growth rate. At high precursor concentrations (0.05–0.5·mol/L), typically used for FSP synthesis, the nanoparticles agglomerated rapidly in the aerosol leading to large...

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

    Science.gov (United States)

    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.

  4. Annealing dependence of residual stress and optical properties of TiO2 thin film deposited by different deposition methods.

    Science.gov (United States)

    Chen, Hsi-Chao; Lee, Kuan-Shiang; Lee, Cheng-Chung

    2008-05-01

    Titanium oxide (TiO(2)) thin films were prepared by different deposition methods. The methods were E-gun evaporation with ion-assisted deposition (IAD), radio-frequency (RF) ion-beam sputtering, and direct current (DC) magnetron sputtering. Residual stress was released after annealing the films deposited by RF ion-beam or DC magnetron sputtering but not evaporation, and the extinction coefficient varied significantly. The surface roughness of the evaporated films exceeded that of both sputtered films. At the annealing temperature of 300 degrees C, anatase crystallization occurred in evaporated film but not in the RF ion-beam or DC magnetron-sputtered films. TiO(2) films deposited by sputtering were generally more stable during annealing than those deposited by evaporation.

  5. Vacuum deposition onto webs, films and foils

    CERN Document Server

    Bishop, Charles A

    2011-01-01

    Roll-to-roll vacuum deposition is the technology that applies an even coating to a flexible material that can be held on a roll and provides a much faster and cheaper method of bulk coating than deposition onto single pieces or non-flexible surfaces, such as glass. This technology has been used in industrial-scale applications for some time, including a wide range of metalized packaging (e.g. snack packets). Its potential as a high-speed, scalable process has seen an increasing range of new products emerging that employ this cost-effective technology: solar energy products are moving from rigid panels onto flexible substrates, which are cheaper and more versatile; in a similar way, electronic circuit 'boards' can be produced on a flexible polymer, creating a new range of 'flexible electronics' products; and, flexible displays are another area of new technology in vacuum coating, with flexible display panels and light sources emerging. Charles Bishop has written this book to meet the need he identified, as a t...

  6. Enhanced Bactericidal Activity of Silver Thin Films Deposited via Aerosol-Assisted Chemical Vapor Deposition

    OpenAIRE

    Ponja, S. D.; Sehmi, S. K.; Allan, E.; MacRobert, A. J.; Parkin, I. P.; Carmalt, C. J.

    2015-01-01

    Silver thin films were deposited on SiO2-barrier-coated float glass, fluorine-doped tin oxide (FTO) glass, Activ glass, and TiO2-coated float glass via AACVD using silver nitrate at 350 °C. The films were annealed at 600 °C and analyzed by X-ray powder diffraction, X-ray photoelectron spectroscopy, UV/vis/near-IR spectroscopy, and scanning electron microscopy. All the films were crystalline, and the silver was present in its elemental form and of nanometer dimension. The antibacterial activit...

  7. Laser-assisted deposition of thin C60 films

    DEFF Research Database (Denmark)

    Schou, Jørgen; Canulescu, Stela; Fæster, Søren

    . However, organic materials are usually not well suited for direct laser irradiation, since the organic molecules may suffer from fragmentation by the laser light. We have, therefore, explored the possible fragmentation of organic molecules by attempting to produce thin films of C60 which is a strongly...... bound carbon molecule with a well-defined mass (M = 720 amu) and therefore a good, organic test molecule. C60 fullerene thin films of average thickness of more than 100 nm was produced in vacuum by matrix-assisted pulsed laser evaporation (MAPLE). A 355 nm Nd:YAG laser was directed onto a frozen target...... of the matrix material, anisole, with a concentration of 0.67 wt% C60. At laser fluences below 1.5 J/cm2, a dominant fraction of the film molecules are C60 transferred to the substrate without any fragmentation. High-resolution SEM images of MAPLE deposited films reveal large circular features on the surface...

  8. High conductivity transparent carbon nanotube films deposited from superacid

    Energy Technology Data Exchange (ETDEWEB)

    Hecht, David S; Lee, Roland; Hu Liangbing [Unidym Incorporated, 1244 Reamwood Drive, Sunnyvale, CA 94089 (United States); Heintz, Amy M; Moore, Bryon; Cucksey, Chad; Risser, Steven, E-mail: dhecht@gmail.com [Battelle, 505 King Avenue, Columbus, OH 43201 (United States)

    2011-02-18

    Carbon nanotubes (CNTs) were deposited from a chlorosulfonic superacid solution onto PET substrates by a filtration/transfer method. The sheet resistance and transmission (at 550 nm) of the films were 60 {Omega}/sq and 90.9% respectively, which corresponds to a DC conductivity of 12 825 S cm{sup -1} and a DC/optical conductivity ratio of 64.1. This is the highest DC conductivity reported for CNT thin films to date, and attributed to both the high quality of the CNT material and the exfoliation/doping by the superacid. This work demonstrates that CNT transparent films have not reached the conductivity limit; continued improvements will enable these films to be used as the transparent electrode for applications in solid state lighting, LCD displays, touch panels, and photovoltaics.

  9. High conductivity transparent carbon nanotube films deposited from superacid.

    Science.gov (United States)

    Hecht, David S; Heintz, Amy M; Lee, Roland; Hu, Liangbing; Moore, Bryon; Cucksey, Chad; Risser, Steven

    2011-02-18

    Carbon nanotubes (CNTs) were deposited from a chlorosulfonic superacid solution onto PET substrates by a filtration/transfer method. The sheet resistance and transmission (at 550 nm) of the films were 60 Ω/sq and 90.9% respectively, which corresponds to a DC conductivity of 12,825 S cm(-1) and a DC/optical conductivity ratio of 64.1. This is the highest DC conductivity reported for CNT thin films to date, and attributed to both the high quality of the CNT material and the exfoliation/doping by the superacid. This work demonstrates that CNT transparent films have not reached the conductivity limit; continued improvements will enable these films to be used as the transparent electrode for applications in solid state lighting, LCD displays, touch panels, and photovoltaics.

  10. Reactive sputtering deposition of SiO2 thin films

    Directory of Open Access Journals (Sweden)

    IVAN RADOVIC

    2008-01-01

    Full Text Available SiO2 layers were deposited in a UHV chamber by 1 keV Ar+ ion sputtering from a high purity silicon target, using different values of the oxygen partial pressure (5×10-6–2×10-4 mbar and of the ion beam current on the target (1.67–6.85 mA. The argon partial pressure during operation of the ion gun was 1×10-3 mbar. The substrate temperature was held at 550 °C and the films were deposited to a thickness of 12.5–150 nm, at a rate from 0.0018–0.035 nm s-1. Structural characterization of the deposited thin films was performed by Rutherford backscattering spectrometry (RBS analysis. Reactive sputtering was proved to be efficient for the deposition of silica at 550 °C, an oxygen partial pressure of 2×10-4 mbar (ion beam current on the target of 5 mA or, at a lower deposition rate, ion beam current of 1.67 mA and an oxygen partial pressure of 6×10-5 mbar. One aspect of these investigations was to study the consumption of oxygen from the gas cylinder, which was found to be lower for higher deposition rates.

  11. Thin film deposition using rarefied gas jet

    Science.gov (United States)

    Pradhan, Sahadev, , Dr.

    2017-01-01

    The rarefied gas jet of aluminium is studied at Mach number Ma =(U_j /√{ kbTj / m }) in the range .01 mass and diameter, and kb is the Boltzmann constant. An important finding is that the capture width (cross-section of the gas jet deposited on the substrate) is symmetric around the centerline of the substrate, and decreases with increased Mach number due to an increase in the momentum of the gas molecules. DSMC simulation results reveals that at low Knudsen number ((Kn =0.01); shorter mean free paths), the atoms experience more collisions, which direct them toward the substrate. However, the atoms also move with lower momentum at low Mach number ,which allows scattering collisions to rapidly direct the atoms to the substrate.

  12. A Comprehensive Study on Mo/CdTe Metal-Semiconductor Interface Deposited by Radio Frequency Magnetron Sputtering.

    Science.gov (United States)

    Dhar, N; Khan, N A; Chelvanathan, P; Akhtaruzzaman, M; Alam, M M; Alothman, Z A; Sopian, K; Amin, N

    2015-11-01

    Metal-semiconductor (MS) junction between Mo and CdTe, which is one of the fundamental issues for CdTe based solar cell, has been investigated for films deposited on different substrates. XRD pattern of Mo/CdTe films on the polyimide (PI) substrate shows a strong preferential orientation of MoTe2 in (100) at 2θ = 29.44 degrees, which becomes less apparent as deposition time of CdTe increases. However, on soda lime glass (SLG) no such XRD reflection pattern is observed. Moreover, from EDX measurement, Mo-Te compound also identifies MoTe2 at Mo/CdTe interface on PI substrate, which is not present on SLG. Bulk carrier concentration of Mo/CdTe films on PI substrate for lower deposition time of CdTe is found 1.42 x 10(18) cm(-3), which is almost equal to MoTe2. Thereafter, it decreases as CdTe growth time increases. The type of unintentionally formed MoTe2 on PI substrate is found to be n-type in nature. Lattice constants of a = 6.5 Å for CdTe and a = 3.52 Å for MoTe2 are found from nanostructure study by TEM.

  13. Electrolytically deposited Cadmium Selenide Films for Photovoltaic Applications

    Directory of Open Access Journals (Sweden)

    Palaiologopoulou M. D.

    2012-10-01

    Full Text Available CdSe films were electrodeposited on pure nickel substrates. The nickel substrate was polished to a mirror finish by Al2O3 paste, etched in 10% HCl solution for 40 s and rinsed thoroughly by de-ionized water. The deposition bath contained solutions with excessive Cd2+ (0.2M from CdSO4 and small amounts of SeO2 (1x10-3 M. The pH of the bath was adjusted to a value of 2.2 at RT by adding 10% H2SO4. The bath was first thermostated at the required temperature, which varied from 55°C to 65°C. Plating was accomplished at deposition potential 1000 mV (vs. Hg/Hg2SO4. The films formed had a uniform thickness and it was found to be approximately 2.0 μm thick (for 20 min electrodeposition process. The produced CdSe films were characterized by X-Ray diffraction and SEM. The induced semiconductor doping effect by thermal annealing in pure dry nitrogen gas was also investigated. Gold contacts were placed on top of the CdSe films, either by evaporation, or mechanically. Depending on the deposition parameters the electrical characteristics of the Ni/CdSe/Au structures may exhibit rectification properties. The optical excitation of the structure was investigated for various CdSe thicknesses.

  14. Chemical bath deposition and characterization of Cu2O-CuxS thin films

    OpenAIRE

    EYA, D. D. O.

    2010-01-01

    Cu2O-CuxS thin films have been deposited on glass substrate by chemical bath deposition technique. The films were obtained by depositing Copper Sulphide (CuxS) on Copper (I) Oxide (Cu2O) and then Cu2O on CuxS. The peak solar transmittance across the thin films were found to be

  15. Homogeneous CdTe quantum dots-carbon nanotubes heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Kayo Oliveira [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil); Bettini, Jefferson [Laboratório Nacional de Nanotecnologia, Centro Nacional de Pesquisa em Energia e Materiais, CEP 13083-970, Campinas, SP (Brazil); Ferrari, Jefferson Luis [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil); Schiavon, Marco Antonio, E-mail: schiavon@ufsj.edu.br [Grupo de Pesquisa em Química de Materiais – (GPQM), Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, Campus Dom Bosco, Praça Dom Helvécio, 74, CEP 36301-160, São João del-Rei, MG (Brazil)

    2015-01-15

    The development of homogeneous CdTe quantum dots-carbon nanotubes heterostructures based on electrostatic interactions has been investigated. We report a simple and reproducible non-covalent functionalization route that can be accomplished at room temperature, to prepare colloidal composites consisting of CdTe nanocrystals deposited onto multi-walled carbon nanotubes (MWCNTs) functionalized with a thin layer of polyelectrolytes by layer-by-layer technique. Specifically, physical adsorption of polyelectrolytes such as poly (4-styrene sulfonate) and poly (diallyldimethylammonium chloride) was used to deagglomerate and disperse MWCNTs, onto which we deposited CdTe quantum dots coated with mercaptopropionic acid (MPA), as surface ligand, via electrostatic interactions. Confirmation of the CdTe quantum dots/carbon nanotubes heterostructures was done by transmission and scanning electron microscopies (TEM and SEM), dynamic-light scattering (DLS) together with absorption, emission, Raman and infrared spectroscopies (UV–vis, PL, Raman and FT-IR). Almost complete quenching of the PL band of the CdTe quantum dots was observed after adsorption on the MWCNTs, presumably through efficient energy transfer process from photoexcited CdTe to MWCNTs. - Highlights: • Highly homogeneous CdTe-carbon nanotubes heterostructures were prepared. • Simple and reproducible non-covalent functionalization route. • CdTe nanocrystals homogeneously deposited onto multi-walled carbon nanotubes. • Efficient energy transfer process from photoexcited CdTe to MWCNTs.

  16. Biaxial CdTe/CaF{sub 2} films growth on amorphous surface

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, W., E-mail: yuanw@rpi.ed [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110, 8th St., Troy, NY 12180 (United States); Tang, F.; Li, H.-F.; Parker, T. [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110, 8th St., Troy, NY 12180 (United States); LiCausi, N. [Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute, 110, 8th St., Troy, NY 12180 (United States); Lu, T.-M. [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110, 8th St., Troy, NY 12180 (United States); Bhat, I. [Department of Electrical, Computer and Systems Engineering, Rensselaer Polytechnic Institute, 110, 8th St., Troy, NY 12180 (United States); Wang, G.-C. [Department of Physics, Applied Physics and Astronomy, Rensselaer Polytechnic Institute, 110, 8th St., Troy, NY 12180 (United States); Lee, S. [US Army Armament Research, Development and Engineering Center, Benet Labs, Watervliet, NY 12189 (United States)

    2009-10-30

    A continuous and highly biaxially textured CdTe film was grown by metal organic chemical vapor deposition on an amorphous substrate using biaxial CaF{sub 2} nanorods as a buffer layer. The interface between the CdTe film and CaF{sub 2} nanorods and the morphology of the CdTe film were studied by transmission electron microscopy (TEM) and scanning electron microscopy. Both the TEM and X-ray pole figure analysis clearly reveal that the crystalline orientation of the continuous CdTe film followed the {l_brace}111{r_brace}<121> biaxial texture of the CaF{sub 2} nanorods. A high density of twin faults was observed in the CdTe film. Furthermore, the near surface texture of the CdTe thin film was investigated by reflection high-energy electron diffraction (RHEED) and RHEED surface pole figure analysis. Twinning was also observed from the RHEED surface pole figure analysis.

  17. Production of selective membranes using plasma deposited nanochanneled thin films

    Directory of Open Access Journals (Sweden)

    Rodrigo Amorim Motta Carvalho

    2006-12-01

    Full Text Available The hydrolization of thin films obtained by tetraethoxysilane plasma polymerization results in the formation of a nanochanneled silicone like structure that could be useful for the production of selective membranes. Therefore, the aim of this work is to test the permeation properties of hydrolyzed thin films. The films were tested for: 1 permeation of polar organic compounds and/or water in gaseous phase and 2 permeation of salt in liquid phase. The efficiency of permeation was tested using a quartz crystal microbalance (QCM technique in gas phase and conductimetric analysis (CA in liquid phase. The substrates used were: silicon for characterization of the deposited films, piezoelectric quartz crystals for tests of selective membranes and cellophane paper for tests of permeation. QCM analysis showed that the nanochannels allow the adsorption and/or permeation of polar organic compounds, such as acetone and 2-propanol, and water. CA showed that the films allow salt permeation after an inhibition time needed for hydrolysis of the organic radicals within the film. Due to their characteristics, the films can be used for grains protection against microorganism proliferation during storage without preventing germination.

  18. Growth and microstructure properties of microcrystalline silicon films deposited using jet-ICPCVD

    Institute of Scientific and Technical Information of China (English)

    Zuo Zewen; Guan Wentian; Xin Yu; Lü Jin; Wang Junzhuan; Pu Lin; Shi Yi; Zheng Youdou

    2011-01-01

    Microcrystalline silicon films were deposited at a high rate and low temperature using jet-type inductively coupled plasma chemical vapor deposition (jet-ICPCVD).An investigation into the deposition rate and microstructure properties of the deposited films showed that a high deposition rate of over 20 nm/s can be achieved while maintaining reasonable material quality.The deposition rate can be controlled by regulating the generation rate and transport of film growth precursors.The film with high crystallinity deposited at low temperature could principally result from hydrogen-induced chemical annealing.

  19. Studies of CdS/CdTe interface: Comparison of CdS films deposited by close space sublimation and chemical bath deposition techniques

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jun-feng, E-mail: pkuhjf@bit.edu.cn [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, UMR CNRS 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France); Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Fu, Gan-hua; Krishnakumar, V.; Schimper, Hermann-Josef [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Liao, Cheng [Department of Physics, Peking University, Beijing 100871 (China); Jaegermann, Wolfram [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Besland, M.P. [Institut des Matériaux Jean Rouxel (IMN), Université de Nantes, UMR CNRS 6502, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 3 (France)

    2015-05-01

    The CdS layers were deposited by two different methods, close space sublimation (CSS) and chemical bath deposition (CBD) technique. The CdS/CdTe interface properties were investigated by transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The TEM images showed a large CSS-CdS grain size in the range of 70-80 nm. The interface between CSS-CdS and CdTe were clear and sharp, indicating an abrupt hetero-junction. On the other hand, CBD-CdS layer had much smaller grain size in the 5-10 nm range. The interface between CBD-CdS and CdTe was not as clear as CSS-CdS. With the stepwise coverage of CdTe layer, the XPS core levels of Cd 3d and S 2p in CSS-CdS had a sudden shift to lower binding energies, while those core levels shifted gradually in CBD-CdS. In addition, XPS depth profile analyses indicated a strong diffusion in the interface between CBD-CdS and CdTe. The solar cells prepared using CSS-CdS yielded better device performance than the CBD-CdS layer. The relationships between the solar cell performances and properties of CdS/CdTe interfaces were discussed. - Highlights: • Studies of CdS deposited by close space sublimation and chemical bath deposition • An observation of CdS/CdTe interface by transmission electron microscope • A careful investigation of CdS/CdTe interface by X ray photoelectron spectra • An easier diffusion at the chemical bath deposition CdS and CdTe interface.

  20. Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells. Final subcontract report, 1 July 1988--31 December 1991

    Energy Technology Data Exchange (ETDEWEB)

    Chu, T.L. [University of South Florida, Tampa, FL (United States)

    1992-04-01

    This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75% or higher at 0. 44 {mu}m and a photovoltaic efficiency of 11.5% or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65% and a photovoltaic conversion efficiency of 5% and 8%, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and metal-organic chemical vapor deposition (MOCVD) technique, (2) depositing CdTe films by close-spaced sublimation (CSS) and MOCVD techniques, (3) preparing and evaluating thin film CdTe solar cells, and (4) preparing and characterizing thin film ZnTe, CD{sub 1-x}Zn{sub 1-x}Te, and Hg{sub 1-x}Zn{sub x}Te solar cells. The deposition of CdS films from aqueous solutions was investigated in detail, and their crystallographic, optical, and electrical properties were characterized. CdTe films were deposited from DMCd and DIPTe at 400{degrees}C using TEGa and AsH{sub 3} as dopants. CdTe films deposited by CSS had significantly better microstructures than those deposited by MOCVD. Deep energy states in CdTe films deposited by CSS and MOCVD were investigated. Thin films of ZnTe, Cd{sub 1- x}Zn{sub x}Te, and Hg{sub 1-x}Zn{sub x}Te were deposited by MOCVD, and their crystallographic, optical, and electrical properties were characterized. 67 refs.

  1. Polymer-assisted deposition of metal-oxide films.

    Science.gov (United States)

    Jia, Q X; McCleskey, T M; Burrell, A K; Lin, Y; Collis, G E; Wang, H; Li, A D Q; Foltyn, S R

    2004-08-01

    Metal oxides are emerging as important materials for their versatile properties such as high-temperature superconductivity, ferroelectricity, ferromagnetism, piezoelectricity and semiconductivity. Metal-oxide films are conventionally grown by physical and chemical vapour deposition. However, the high cost of necessary equipment and restriction of coatings on a relatively small area have limited their potential applications. Chemical-solution depositions such as sol-gel are more cost-effective, but many metal oxides cannot be deposited and the control of stoichiometry is not always possible owing to differences in chemical reactivity among the metals. Here we report a novel process to grow metal-oxide films in large areas at low cost using polymer-assisted deposition (PAD), where the polymer controls the viscosity and binds metal ions, resulting in a homogeneous distribution of metal precursors in the solution and the formation of uniform metal-organic films. The latter feature makes it possible to grow simple and complex crack-free epitaxial metal-oxides.

  2. Liposomes as drug deposits in multilayered polymer films.

    Science.gov (United States)

    Lynge, Martin E; Laursen, Marie Baekgaard; Hosta-Rigau, Leticia; Jensen, Bettina E B; Ogaki, Ryosuke; Smith, Anton A A; Zelikin, Alexander N; Städler, Brigitte

    2013-04-24

    The ex vivo growth of implantable hepatic or cardiac tissue remains a challenge and novel approaches are highly sought after. We report an approach to use liposomes embedded within multilayered films as drug deposits to deliver active cargo to adherent cells. We verify and characterize the assembly of poly(l-lysine) (PLL)/alginate, PLL/poly(l-glutamic acid), PLL/poly(methacrylic acid) (PMA), and PLL/cholesterol-modified PMA (PMAc) films, and assess the myoblast and hepatocyte adhesion to these coatings using different numbers of polyelectrolyte layers. The assembly of liposome-containing multilayered coatings is monitored by QCM-D, and the films are visualized using microscopy. The myoblast and hepatocyte adhesion to these films using PLL/PMAc or poly(styrenesulfonate) (PSS)/poly(allyl amine hydrochloride) (PAH) as capping layers is evaluated. Finally, the uptake of fluorescent lipids from the surface by these cells is demonstrated and compared. The activity of this liposome-containing coating is confirmed for both cell lines by trapping the small cytotoxic compound thiocoraline within the liposomes. It is shown that the biological response depends on the number of capping layers, and is different for the two cell lines when the compound is delivered from the surface, while it is similar when administered from solution. Taken together, we demonstrate the potential of liposomes as drug deposits in multilayered films for surface-mediated drug delivery.

  3. Ultraviolet optical properties of aluminum fluoride thin films deposited by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hennessy, John, E-mail: john.j.hennessy@jpl.nasa.gov; Jewell, April D.; Balasubramanian, Kunjithapatham; Nikzad, Shouleh [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

    2016-01-15

    Aluminum fluoride (AlF{sub 3}) is a low refractive index material with promising optical applications for ultraviolet (UV) wavelengths. An atomic layer deposition process using trimethylaluminum and anhydrous hydrogen fluoride has been developed for the deposition of AlF{sub 3} at substrate temperatures between 100 and 200 °C. This low temperature process has resulted in thin films with UV-optical properties that have been characterized by ellipsometric and reflection/transmission measurements at wavelengths down to 200 nm. The optical loss for 93 nm thick films deposited at 100 °C was measured to be less than 0.2% from visible wavelengths down to 200 nm, and additional microstructural characterization demonstrates that the films are amorphous with moderate tensile stress of 42–105 MPa as deposited on silicon substrates. X-ray photoelectron spectroscopy analysis shows no signature of residual aluminum oxide components making these films good candidates for a variety of applications at even shorter UV wavelengths.

  4. Poly-para-xylylene thin films: A study of the deposition chemistry, kinetics, film properties, and film stability

    Science.gov (United States)

    Fortin, Jeffrey Bernard

    Poly-para-xylylene, or parylene, thin films are chemically vapor deposited (CVD), conformal, pin-hole free polymeric thin films. They have found many industrial uses since there invention in 1947 and continue to find new applications in micro-electronics, biotechnology, and micro-electro-mechanical systems. In this study the deposition chemistry, deposition kinetics, film properties, and film stability were investigated. A differentially pumped quadrupole mass spectrometer was used to analyze the vapor species present during the CVD process. The identity of dimer contamination and its impact on the CVD process and film properties was studied. The quantitative conversion of dimer to monomer was investigated and it was found that conversion begins at around 385°C and by 565°C 100% conversion is obtained. The kinetics of the CVD process was analyzed for a range of substrate temperatures and chamber pressures. A new kinetic model based on a two-step adsorption was developed and fit the kinetic data well. This model should be appropriate for use with all parylene family polymers. Many of the properties of the films deposited in this study were analyzed. This includes a detailed study of surface morphology using atomic force microscopy which shows the interface width increases as a power law of film thickness. Other properties analyzed were the thermal stability, electrical properties, index of refraction, birefringence, hardness, and elastic modulus. The effect of ultraviolet (UV) radiation of lambda ≥ 250 nm on the thermal stability, electrical, and optical properties of thin parylene films was studied. The thermal stability and electrical properties of UV treated films were seen to deteriorate as the radiation dose increased. The stability of parylene thin films receiving plasma etching was analyzed. The dielectric constant, dissipation factor, and leakage current of plasma etched thin parylene films were investigated and found to be stable for the range of

  5. Synthesis, deposition and characterization of ferroelectric films for electrooptic devices

    Science.gov (United States)

    Tunaboylu, Bahadir

    The use of integrable ferroelectric electro-optic thin films is a revolutionary approach in the development of high-speed, low-voltage and high-contrast ratio integrated electro-optic spatial light modulators (SLM) for free-space optoelectronic interconnects. Thin films offer improved performance over bulk ferroelectric (FE) materials because of their lower modulator capacitance and operation at high speeds with low switching energies. Integration of ferroelectric thin films with silicon technology will also impact both the uncooled infrared sensor and dynamic and nonvolatile memory technologies. Ferroelectrics such as lead lanthanum zirconate titanate (PLZT) and patassium tantalate niobate (KTN) present great potential for SLMs due to their large electro-optic (EO) effect in the bulk form. The development of thin-film SLMs require electro-optic films of high optical quality with good dielectric and EO properties. High quality thin films of PLZT and KTN were deposited using RF magnetron sputtering on r-plane sapphire substrates which offer integration capability with semiconductor devices. PLZT films with extremely large peak dielectric constant, 2800 at the Curie temperature of 180sp°C, were achieved with remarkably low dissipation loss factor dielectric frequency dispersion was determined to be very small up to 1 Mhz. Also, the absorption of the light in the films was very low. A giant effective quadratic electrooptic effect was demonstrated in PLZT films. These results represent a huge leap forward for the FE-SLM technology with respect to the goal of fully integrated thin film electrooptic light modulators. Microstructural development and phase transformation kinetics in PLZT films were also analyzed for the first time and are presented here. Energy required for the formation of desirable perovskite phase was determined to be 322 kJ/mol. Single-phase PLZT films with larger average grain size showed higher dielectric constants and better EO properties as

  6. Deposition and consolidation of porous ceramic films for membrane separation

    DEFF Research Database (Denmark)

    Elmøe, Tobias Dokkedal; Tricoli, Antonio; Johannessen, Tue

    The deposition of porous ceramic films for membrane separation can be done by several processes such as thermophoresis [1], dip-coating [2] and spray pyrolysis [3]. Here we present a high-speed method, in which ceramic nano-particles form a porous film by filtration on top of a porous ceramic...... substrate [4]. Ceramic nano-particles are generated in a flame, using either a premixed (gas) flame, in which a metal-oxide precursor is evaporated in an N2 stream, which is combusted with methane and air, or using a flame spray pyrolysis, in which a liquid metal-oxide precursor is sprayed through a nozzle...

  7. Thin-film cadmium telluride solar cells

    Science.gov (United States)

    Chu, T. L.

    1986-08-01

    The major objective of this work was to demonstrate CdTe devices grown by chemical vapor deposition (CVD) with a total area greater than 1 cm2 and photovoltic efficiencies of at least 13%. During the period covered, various processing steps were investigated for the preparation of thin-film CdTe heterojunction solar cells of the inverted configuration. Glass coated with fluorine-doped tin oxide was used as the substrate. Thin-film heterojunction solar cells were prepared by depositing p-CdTe films on substrates using CVD and close-spaced sublimation (CSS). Cells prepared from CSS CdTe usually have a higher conversion efficiency than those prepared from CVD CdTe, presumably due to the chemical interaction between CdS and CdTe at the interface during the CVD process. The best cell, about 1.2 sq cm in area, had an AM 1.5 (global) efficiency of 10.5%, and further improvements are expected by optimizing the process parameters.

  8. Structural and Optical Properties of Chemical Bath Deposited Silver Oxide Thin Films: Role of Deposition Time

    Directory of Open Access Journals (Sweden)

    A. C. Nwanya

    2013-01-01

    Full Text Available Silver oxide thin films were deposited on glass substrates at a temperature of 50°C by chemical bath deposition technique under different deposition times using pure AgNO3 precursor and triethanolamine as the complexing agent. The chemical analysis based on EDX technique shows the presence of Ag and O at the appropriate energy levels. The morphological features obtained from SEM showed that the AgxO structures varied as the deposition time changes. The X-ray diffraction showed the peaks of Ag2O and AgO in the structure. The direct band gap and the refractive index increased as the deposition time increased and was in the range of 1.64–1.95 eV and 1.02–2.07, respectively. The values of the band gap and refractive index obtained indicate possible applications in photovoltaic and photothermal systems.

  9. Auger relative sensitivivity factors for CdTe oxide

    OpenAIRE

    P. Bartolo-Pérez; J. L. Peña; M.H. Farías

    1999-01-01

    The Auger lineshape of Te MNN in measurements of Auger spectra of CdTe oxide films with various degrees of oxidation was analyzed. By using standards from stoichiometric compounds, Auger relative sensitivity factors (RSF´s) of Cd, Te and O for CdTe oxide thin films were obtained. The value of the RFS of oxygen is about constant, 0.27-0.28, for the standard compound, CdO, TeO2 and CdTeO3 (considering the RSF of Cd as 1). However, the obtained RSF of Te changes from 0.69 in CdTe up to 0.87 in C...

  10. Process Development for High Voc CdTe Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Ferekides, C. S.; Morel, D. L.

    2011-05-01

    This is a cumulative and final report for Phases I, II and III of this NREL funded project (subcontract # XXL-5-44205-10). The main research activities of this project focused on the open-circuit voltage of the CdTe thin film solar cells. Although, thin film CdTe continues to be one of the leading materials for large-scale cost-effective production of photovoltaics, the efficiency of the CdTe solar cells have been stagnant for the last few years. This report describes and summarizes the results for this 3-year research project.

  11. Properties of Te-rich cadmium telluride thin films fabricated by closed space sublimation technique

    Science.gov (United States)

    Abbas Shah, N.; Ali, A.; Ali, Z.; Maqsood, A.; Aqili, A. K. S.

    2005-11-01

    Cadmium telluride (CdTe) thin films were prepared by the closed space sublimation (CSS) technique, using CdTe powder as evaporant onto substrates of water-white glass. In the next step, the same procedure was adopted by using tellurium as evaporant and already deposited CdTe film as substrate. Such compositions were then annealed at 300 °C for 30 min to obtain Te-enriched films. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), spectrophotometry, DC electrical resistivity, dark conductivity and activation energy analysis as a function of temperature by two-probe method. The electron microprobe analyzer (EMPA) results showed an increase of Te content composition in the samples as the mass of the Te-deposition increased in CdTe. The Hall measurements indicated the increase in mobility and carrier concentrations of CdTe films by addition of tellurium. A significant change in the shape and size of the CdTe grains were observed.

  12. Electrophoretic deposition and constrained sintering of strontium titanate thick films

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, Luís; Vilarinho, Paula M., E-mail: paula.vilarinho@ua.pt; Senos, Ana M.R.

    2015-01-15

    Thick films of functional oxides are currently substituting counterparts bulk ceramics, as in the case of low loss dielectrics. For SrTiO{sub 3} (ST) based compositions it is demonstrated that electrophoretic deposition (EPD), using acetone as a suspension media with iodine addition, is a suitable technology to fabricate 12 μm thick films. The microstructural analysis of the films sintered at 1500 °C shows that highly densified microstructures can be obtained and, by slightly varying the Sr/Ti stoichiometry in the powder composition, increased densification and grain size and enlargement of the distribution with decreasing Sr/Ti ratio can be observed. In spite of the high densification of the films, it is also demonstrated that due to the constraint imposed by the substrate a smaller grain size is observed in thick films as compared to equivalent bulk ceramics. In addition, a preferential vertical pore orientation is observed in ST thick films. These results may have broad implications if one considers that the dielectric losses and dielectric tunability is affected by pore orientation, since it affects the electric field distribution. - Highlights: • Nonstoichiometry effect on microstructure of constrained sintered thick films and bulk is similar. • Increased densification and grain size and enlargement of distribution with decreasing Sr/Ti ratio. • Independent of Sr/Ti ratio smaller grain size for thick films compared to ceramics. • Preferential vertical pore orientation for constrained sintering of thick films. • Anisotropic porosity as tailoring factor to engineer permittivity and tunability.

  13. The structural characterisation of HWCVD-deposited nanocrystalline silicon films

    Directory of Open Access Journals (Sweden)

    Bibhu P. Swain

    2009-12-01

    Full Text Available Nanocrystalline silicon (nc-Si films were deposited by hot-wire chemical vapour deposition (HWCVD in the presence of varying H2 concentrations and their structural and interfacial character investigated by X-ray diffraction, small-angle X-ray scattering (SAXS and Raman spectroscopy. The crystalline fraction was around 30–50% and the nc-Si crystallite size was in the range 20–35 nm. The SAXS results were analysed by Guinier plot, scaling factor, and correlation distance. The nc-Si grains displayed a mass fractal appearance, and the interfacial inhomogeneity distance was ~2 nm.

  14. Growth Model for Pulsed-Laser Deposited Perovskite Oxide Films

    Institute of Scientific and Technical Information of China (English)

    WANG Xu; FEI Yi-Yan; ZHU Xiang-Dong; Lu Hui-Bin; YANG Guo-Zhen

    2008-01-01

    We present a multi-level growth model that yields some of the key features of perovskite oxide film growth as observed in the reflection high energy electron diffraction(RHEED)and ellipsometry studies.The model describes the effect of deposition,temperature,intra-layer transport,interlayer transport and Ostwald ripening on the morphology of a growth surface in terms of the distribution of terraces and step edges during and after deposition.The numerical results of the model coincide well with the experimental observation.

  15. Research on fabrication technology for thin film solar cells for practical use. Research on low-cost fabrication technology for large-area modules (CdS/CdTe solar cell modules); Usumaku taiyo denchi seizo gijutsu no jitsuyoka kenkyu. Daimenseki module no tei cost seizo gijutsu (CdTe taiyo denchi module seizo no gijutsu kaihatsu)

    Energy Technology Data Exchange (ETDEWEB)

    Tatsuta, M. [New Energy and Industrial Technology Development Organization, Tokyo (Japan)

    1994-12-01

    This paper reports the study results on the fabrication technology of CdS/CdTe solar cell modules in fiscal 1994. (1) On the fabrication technology for high-efficiency large-area solar cells, high-quality CdTe active layer was studied. S content taken in the active layer at sintering of CdTe decreased with an increase in formed CdTe, resulting in improvement of Voc of cells. (2) On the window layer with wide band gap, the solar cell superior in collection efficiency and photoelectric characteristics could be obtained using the newly developed mixed crystal film of Cd(1-x)Zn(x)S. (3) On the forming technology of large-area coating/sintering films, improvement of CdS film quality was studied by pressurized processing of printed CdS films. As a result, improvement of film density and light transmissivity was confirmed. (4) On the leveling process technology of CdTe films, smooth surface films were obtained by experiment using an equipment simultaneously exciting samples in all directions as one of uniform coating methods of films. 7 figs.

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

    Science.gov (United States)

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

    2016-09-01

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

  17. Methods of Boron-carbon Deposited Film Removal

    Science.gov (United States)

    Airapetov, A.; Terentiev, V.; Voituk, A.; Zakharov, A.

    Boron carbide was proposed as a material for in-situ renewable protecting coating for tungsten tiles of the ITER divertor. It is necessary to develop a method of gasification of boron-carbon film which deposits during B4C sputtering. In this paper the results of the first stage investigation of gasification methods of boron-carbon films are presented. Two gasification methods of films are investigated: interaction with the ozone-oxygen mixture and irradiation in plasma with the working gas composed of oxygen, ethanol, and, in some cases, helium. The gasification rate in the ozone-oxygen mixture at 250 °C for B/C films with different B/C ratio and carbon fiber composite (CFC), was measured. For B/C films the gasification rate decreased with increasing B/C ratio (from 45 nm/h at B/C=0.7 to 4 nm/h at B/C=2.1; for CFC - 15 μm/h). Films gasification rates were measured under ion irradiation from ethanol-oxygen-helium plasma at different temperatures, with different ion energies and different gas mixtures. The maximum obtained removal rate was near 230 nm/h in case of ethanol-oxygen plasma and at 150°C of the sample temperature.

  18. Raman spectra of amorphous carbon films deposited by SWP

    Science.gov (United States)

    Xu, Junqi; Liu, Weiguo; Hang, Lingxia; Su, Junhong; Fan, Huiqing

    2010-10-01

    Amorphous carbon film is one of the most important anti-reflection protective films coated on infrared optical components. In this paper, hydrogen-free amorphous carbon films were deposited by new type surface-wave-sustained plasma (SWP) source with a graphite target at various experiment parameters. The laser Raman spectroscopy at wavelength of 514 nm was used to investigate the structure and bonding of these carbon films. The results showed consanguineous correlations between the intensity ratio ID/IG and the experiment parameters such as microwave power, target voltage and gas pressure applied to the SWP source. Raman spectra proved the structure of these carbon films prepared by SWP technique is typical diamond-like carbon (DLC). The analysis on G peak position and intensity ratio ID/IG indicated that Raman shifts moves to low wavenumber and ID/IG decreases with the increasing of microwave power from 150 W to 330 W. These results means the formation of sp3 bond prefers higher microwave power. DLC films prepared at target voltage of -200 V have higher sp3 content than that of -350 V, moreover, an increase of gas pressure during experiments yields higher sp3 content at the microwave power below 270 W, whereas the change of sp3 content is slight with the various conditions when microwave power exceeds 270 W.

  19. Reactive pulsed laser deposition of gold nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Caricato, A.P. [University of Salento, Department of Physics, 73100 Lecce (Italy); Fernandez, M. [University of Salento, Department of Physics, 73100 Lecce (Italy); Leggieri, G. [University of Salento, Department of Physics, 73100 Lecce (Italy)]. E-mail: leggieri@le.infn.it; Luches, A. [University of Salento, Department of Physics, 73100 Lecce (Italy); Martino, M. [University of Salento, Department of Physics, 73100 Lecce (Italy); Romano, F. [University of Salento, Department of Physics, 73100 Lecce (Italy); Tunno, T. [University of Salento, Department of Physics, 73100 Lecce (Italy); Valerini, D. [University of Salento, Department of Physics, 73100 Lecce (Italy); Verdyan, A. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Soifer, Y.M. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Azoulay, J. [Science Department, Holon Academic Institute of Technology, Holon 58102 (Israel); Meda, L. [IGD Polimeri Europa S.p.A, Novara (Italy)

    2007-07-31

    We report on the growth and characterization of gold nitride thin films on Si <1 0 0> substrates at room temperature by reactive pulsed laser ablation. A pure (99.95%) Au target was ablated with KrF excimer laser pulses in nitrogen containing atmosphere (N{sub 2} or NH{sub 3}). The gas ambient pressure was varied in the range 0.1-100 Pa. The morphology of the films was studied by using optical, scanning electron and atomic force microscopy, evidencing compact films with RMS roughness in the range 3.6-35.1 nm, depending on the deposition pressure. Rutherford backscattering spectrometry and energy dispersion spectroscopy (EDS) were used to detect the nitrogen concentration into the films. The EDS nitrogen peak does not decrease in intensity after 2 h annealing at 250 deg. C. Film resistivity was measured using a four-point probe and resulted in the (4-20) x 10{sup -8} {omega} m range, depending on the ambient pressure, to be compared with the value 2.6 x 10{sup -8} {omega} m of a pure gold film. Indentation and scratch measurements gave microhardness values of 2-3 GPa and the Young's modulus close to 100 GPa. X-ray photoemission spectra clearly showed the N 1s peak around 400 eV and displaced with respect to N{sub 2} phase. All these measurements point to the formation of the gold nitride phase.

  20. Reactive pulsed laser deposition of gold nitride thin films

    Science.gov (United States)

    Caricato, A. P.; Fernàndez, M.; Leggieri, G.; Luches, A.; Martino, M.; Romano, F.; Tunno, T.; Valerini, D.; Verdyan, A.; Soifer, Y. M.; Azoulay, J.; Meda, L.

    2007-07-01

    We report on the growth and characterization of gold nitride thin films on Si substrates at room temperature by reactive pulsed laser ablation. A pure (99.95%) Au target was ablated with KrF excimer laser pulses in nitrogen containing atmosphere (N 2 or NH 3). The gas ambient pressure was varied in the range 0.1-100 Pa. The morphology of the films was studied by using optical, scanning electron and atomic force microscopy, evidencing compact films with RMS roughness in the range 3.6-35.1 nm, depending on the deposition pressure. Rutherford backscattering spectrometry and energy dispersion spectroscopy (EDS) were used to detect the nitrogen concentration into the films. The EDS nitrogen peak does not decrease in intensity after 2 h annealing at 250 °C. Film resistivity was measured using a four-point probe and resulted in the (4-20) × 10 -8 Ω m range, depending on the ambient pressure, to be compared with the value 2.6 × 10 -8 Ω m of a pure gold film. Indentation and scratch measurements gave microhardness values of 2-3 GPa and the Young's modulus close to 100 GPa. X-ray photoemission spectra clearly showed the N 1s peak around 400 eV and displaced with respect to N 2 phase. All these measurements point to the formation of the gold nitride phase.

  1. DLC Films Deposited by the DC PACVD Method

    Directory of Open Access Journals (Sweden)

    D. Palamarchuk

    2003-01-01

    Full Text Available DLC (Diamond-Like Carbon coatings have been suggested as protective surface layers against wear. However hard DLC coatings, especially those of greater thickness, have poor adhesion to substrates. We have used several ways to increase the adhesion of DLC coatings prepared by the PACVD (Plasma Assisted Chemical Vapour Deposition method on steel substrates. One of these is the DC PACVD method for preparing DLC films.

  2. DLC Films Deposited by the DC PACVD Method

    OpenAIRE

    D. Palamarchuk; M. Zoriy; J. Gurovič; F. Černý; S. Konvičková; I. Hüttel

    2003-01-01

    DLC (Diamond-Like Carbon) coatings have been suggested as protective surface layers against wear. However hard DLC coatings, especially those of greater thickness, have poor adhesion to substrates. We have used several ways to increase the adhesion of DLC coatings prepared by the PACVD (Plasma Assisted Chemical Vapour Deposition) method on steel substrates. One of these is the DC PACVD method for preparing DLC films.

  3. Carbon film deposition from high velocity rarefied flow

    Energy Technology Data Exchange (ETDEWEB)

    Rebrov, A.K., E-mail: rebrov@itp.nsc.ru; Emelyanov, A.A.; Yudin, I.B.

    2015-01-30

    The presented study is based on the idea of the activation of a gas-precursor high velocity flow by hot wire. The wire forms the channel for flow before expansion to substrate. The construction allows change of the specific flow rate, velocity, composition and temperature of a gas mixture by studying the film synthesis in conditions from free molecular to continuum flow at velocities from hundreds to thousands of m/s. At a high pressure, the film has typical and unusual hexagonal incorporations for diamond tetragonal particles. Raman spectrum with the pronounced diamond peak is typical for diamond-like film. X-ray diffraction points in the presence of lonsdaleite. Conditions of deposition were simulated by Monte Carlo method. Collisions with hot surfaces and chemical transformations were taken into consideration as well.

  4. Nanostructured zinc oxide thin film by simple vapor transport deposition

    Science.gov (United States)

    Athma, P. V.; Martinez, Arturo I.; Johns, N.; Safeera, T. A.; Reshmi, R.; Anila, E. I.

    2015-09-01

    Zinc oxide (ZnO) nanostructures find applications in optoelectronic devices, photo voltaic displays and sensors. In this work zinc oxide nanostructures in different forms like nanorods, tripods and tetrapods have been synthesized by thermal evaporation of zinc metal and subsequent deposition on a glass substrate by vapor transport in the presence of oxygen. It is a comparatively simpler and environment friendly technique for the preparation of thin films. The structure, morphology and optical properties of the synthesized nanostructured thin film were characterized in detail by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and photoluminescence (PL). The film exhibited bluish white emission with Commission International d'Eclairage (CIE) coordinates x = 0.22, y = 0.31.

  5. Chemical vapor deposition of amorphous ruthenium-phosphorus alloy films

    Energy Technology Data Exchange (ETDEWEB)

    Shin Jinhong [Texas Materials Institute, University of Texas at Austin, Austin, TX 78750 (United States); Waheed, Abdul [Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States); Winkenwerder, Wyatt A. [Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712 (United States); Kim, Hyun-Woo [Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712 (United States); Agapiou, Kyriacos [Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States); Jones, Richard A. [Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712 (United States); Hwang, Gyeong S. [Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712 (United States); Ekerdt, John G. [Department of Chemical Engineering, University of Texas at Austin, Austin, TX 78712 (United States)]. E-mail: ekerdt@che.utexas.edu

    2007-05-07

    Chemical vapor deposition growth of amorphous ruthenium-phosphorus films on SiO{sub 2} containing {approx} 15% phosphorus is reported. cis-Ruthenium(II)dihydridotetrakis-(trimethylphosphine), cis-RuH{sub 2}(PMe{sub 3}){sub 4} (Me = CH{sub 3}) was used at growth temperatures ranging from 525 to 575 K. Both Ru and P are zero-valent. The films are metastable, becoming increasingly more polycrystalline upon annealing to 775 and 975 K. Surface studies illustrate that demethylation is quite efficient near 560 K. Precursor adsorption at 135 K or 210 K and heating reveal the precursor undergoes a complex decomposition process in which the hydride and trimethylphosphine ligands are lost at temperatures as low at 280 K. Phosphorus and its manner of incorporation appear responsible for the amorphous-like character. Molecular dynamics simulations are presented to suggest the local structure in the films and the causes for phosphorus stabilizing the amorphous phase.

  6. EPD-deposited ZnO thin films: a review

    Energy Technology Data Exchange (ETDEWEB)

    Verde, M.

    2014-07-01

    ZnO-based materials and specifically ZnO films with tailored morphology have been subjected to extensive research in the past few years due to their high potential for multiple prospective applications, mainly in electronics. Electrophoretic Deposition (EPD) constitutes an economical, eco friendly, low energy consuming and easily scalable alternative to the high energy consuming evaporative techniques which are commonly used for the obtaining of these ZnO films. For its application, however, the use of stable, well dispersed suspensions is a necessary requirement, and thus a thorough study of their colloidal chemistry is essential. In this work the main contributions to the study of colloidal chemistry of ZnO nanoparticle suspensions and their shaping into ZnO films by EPD are summarized. (Author)

  7. Magnetic Phases of Sputter Deposited Thin-Film Erbium

    Science.gov (United States)

    Witt, J. D. S.; Cooper, J. F. K.; Satchell, N.; Kinane, C. J.; Curran, P. J.; Bending, S. J.; Langridge, S.; Heyderman, L. J.; Burnell, G.

    2016-12-01

    We present a detailed structural and magnetic characterization of sputter deposited thin film erbium, determined by x-ray diffraction, transport measurements, magnetometry and neutron diffraction. This provides information on the onset and change of the magnetic state as a function of temperature and applied magnetic field. Many of the features of bulk material are reproduced. Also of interest is the identification of a conical magnetic state which repeats with a wavevector parallel to the c axis τc = 4/17 in units of the reciprocal lattice parameter c*, which is a state not observed in any other thin film or bulk measurements. The data from the various techniques are combined to construct magnetic field, temperature (H, T)–phase diagrams for the 200 nm-thick Er sample that serves as a foundation for future exploitation of this complex magnetic thin film system.

  8. Electrochemical deposition of conductive and adhesive polypyrrole-dopamine films

    Science.gov (United States)

    Kim, Semin; Jang, Lindy K.; Park, Hyun S.; Lee, Jae Young

    2016-07-01

    Electrode surfaces have been widely modified with electrically conductive polymers, including polypyrrole (PPY), to improve the performance of electrodes. To utilize conductive polymers for electrode modification, strong adhesion between the polymer films and electrode substrates should be ensured with high electrical/electrochemical activities. In this study, PPY films were electrochemically polymerized on electrodes (e.g., indium tin oxide (ITO)) with dopamine as a bio-inspired adhesive molecule. Efficient and fast PPY electrodeposition with dopamine (PDA/PPY) was found; the resultant PDA/PPY films exhibited greatly increased adhesion strengths of up to 3.7 ± 0.8 MPa and the modified electrodes had electrochemical impedances two to three orders of magnitude lower than that of an unmodified electrode. This electrochemical deposition of adhesive and conductive PDA/PPY offers a facile and versatile electrode modification for various applications, such as biosensors and batteries.

  9. Supercritical fluid molecular spray film deposition and powder formation

    Science.gov (United States)

    Smith, Richard D.

    1986-01-01

    Solid films are deposited, or fine powders formed, by dissolving a solid material into a supercritical fluid solution at an elevated pressure and then rapidly expanding the solution through a short orifice into a region of relatively low pressure. This produces a molecular spray which is directed against a substrate to deposit a solid thin film thereon, or discharged into a collection chamber to collect a fine powder. Upon expansion and supersonic interaction with background gases in the low pressure region, any clusters of solvent are broken up and the solvent is vaporized and pumped away. Solute concentration in the solution is varied primarily by varying solution pressure to determine, together with flow rate, the rate of deposition and to control in part whether a film or powder is produced and the granularity of each. Solvent clustering and solute nucleation are controlled by manipulating the rate of expansion of the solution and the pressure of the lower pressure region. Solution and low pressure region temperatures are also controlled.

  10. Superconducting niobium nitride films deposited by unbalanced magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Olaya, J.J. [Departamento de Ingenieria Mecanica y Mecatronica, Universidad Nacional de Colombia, Ciudad Universitaria, Carrera 30 Numero 45-03, Bogota (Colombia); Huerta, L. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito exterior s/n, CU Coyoacan, Mexico D.F. 04510 (Mexico); Rodil, S.E. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito exterior s/n, CU Coyoacan, Mexico D.F. 04510 (Mexico)], E-mail: ser42@iim.unam.mx; Escamilla, R. [Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Circuito exterior s/n, CU Coyoacan, Mexico D.F. 04510 (Mexico)

    2008-10-01

    Niobium nitride (NbN) thin films were deposited under different configurations of the magnetic field using a magnetron sputtering system. The magnetic field configuration varied from balanced to unbalanced leading to different growth conditions and film properties. The aim of the paper was to identify correlations between deposition conditions, film properties and the electrical properties, specially the superconductive critical temperature (T{sub C}). The results suggested that there is a critical deposition condition, having an optimum ion-atom arrival ratio that promotes a well ordered and textured nanocrystalline structure (cubic phase) with the minimum residual stress and only under this condition a high critical temperature (16K) was obtained. Lower T{sub C} values around 12K were obtained for the NbN samples having a lower degree of structural perfection and texture, and a larger fraction of intergranular voids. On the other hand, analysis of valence-band spectra showed that the contribution of the Nb 4d states remained essentially constant while the higher T{sub C} was correlated to a higher contribution of the N 2p states.

  11. Effects of Stoichiometry in Undoped CdTe Heteroepilayers on Si

    Energy Technology Data Exchange (ETDEWEB)

    Gessert, Timothy A.; Colegrove, Eric; Stafford, Brian; Gao, Wei; Sivananthan, Siva; Kuciauskas, Darius; Moutinho, Helio; Farrell, Stuart; Barnes, Teresa

    2015-06-14

    Crystalline CdTe layers have been grown heteroepitaxially onto crystalline Si substrates to establish material parameters needed for advanced photovoltaic (PV) device development and related simulation. These studies suggest that additional availability of the intrinsic anion (i.e., Te) during molecular beam epitaxy deposition can improve structural and optoelectronic quality of the epilayer and the interface between Si substrate and the epilayer. This is seen most notably for thin CdTe epitaxial films (<; ~10 micrometers). Although these observations are foundationally important, they are also relevant to envisioned high-performance multijunction II-VI alloy PV devices-where thin layers will be required to achieve production costs aligned with market constraints.

  12. Technology support for high-throughput processing of thin-film CdTe PV modules: Annual technical report, Phase 1, 1 April 1998--31 March 1999

    Energy Technology Data Exchange (ETDEWEB)

    Rose, D.H.; Powell, R.C.; Grecu, D.; Jayamaha, U.; Hanak, J.J.; Bohland, J.; Smigielski, K.; Dorer, G.L.

    1999-10-25

    This report describes work performed by First Solar, L.L.C., during Phase 1 of this 3-year subcontract. The research effort of this subcontract is divided into four areas: (1) process and equipment development, (2) efficiency improvement, (3) characterization and analysis, and (4) environmental, health, and safety. As part of the process development effort, the output of the pilot-production facility was increased. More than 6,200 8-ft{sup 2} CdS/CdTe plates were produced during Phase 1--more than double the total number produced prior to Phase 1. This increase in pilot-production rate was accomplished without a loss in the PV conversion efficiency: the average total-area AM1.5 efficiency of sub-modules produced during the reporting period was 6.4%. Several measurement techniques, such as large-area measurement of CdS thickness, were developed to aid process improvement, and the vapor-transport deposition method was refined. CdTe thickness uniformity and reproducibility were improved. From a population of more than 1,100 plates, the mean standard deviation within a plate was 7.3% and the standard deviation of individual-plate averages was 6.8%. As part of the efficiency-improvement task, research was done on devices with thin-CdS and buffer layers. A cell with 13.9% efficiency was produced on a high-quality substrate, and higher than 12% efficiency was achieved with a cell with no CdS layer. A number of experiments were performed as part of the characterization and analysis task. The temperature dependence of CdTe modules was investigated; the power output was found to be relatively insensitive (<5%) to temperature in the 25 to 50 C range. As part of the characterization and analysis task, considerable effort was also given to reliability verification and improvement. The most carefully monitored array, located at the NREL, was found to have unchanged power output within the margin of error of measurement (5%) after 5 years in the field. The first round of National

  13. Structural and electrical properties of electric field assisted spray deposited pea structured ZnO film

    Science.gov (United States)

    Chaturvedi, Neha; Swami, Sanjay Kumar; Dutta, Viresh

    2016-05-01

    Spray deposition of ZnO film was carried out. The uneven growth of ZnO nanostructures is resulted for spray deposited ZnO film. Application of DC voltage (1000V) during spray deposition provides formation of pea like structures with uniform coverage over the substrate. Electric field assisted spray deposition provides increased crystallinity with reduced resistivity and improved mobility of the ZnO film as compared to spray deposited ZnO film without electric field. This with large area deposition makes the process more efficient than other techniques.

  14. Plasma-enhanced Deposition of Nano-Structured Carbon Films

    Institute of Scientific and Technical Information of China (English)

    Yang Qiaoqin (杨巧勤); Xiao Chijin (肖持进); A. Hirose

    2005-01-01

    By pre-treating substrate with different methods and patterning the catalyst, selective and patterned growth of diamond and graphitic nano-structured carbon films have been realized through DC Plasma-Enhanced Hot Filament Chemical Vapor Deposition (PE-HFCVD).Through two-step processing in an HFCVD reactor, novel nano-structured composite diamond films containing a nanocrystalline diamond layer on the top of a nanocone diamond layer have been synthesized. Well-aligned carbon nanotubes, diamond and graphitic carbon nanocones with controllable alignment orientations have been synthesized by using PE-HFCVD. The orientation of the nanostructures can be controlled by adjusting the working pressure. In a Microwave Plasma Enhanced Chemical Vapor Deposition (MW-PECVD) reactor, high-quality diamond films have been synthesized at low temperatures (310 ℃~550 ℃) without adding oxygen or halogen gas in a newly developed processing technique. In this process, carbon source originates from graphite etching, instead of hydrocarbon. The lowest growth temperature for the growth of nanocrystalline diamond films with a reasonable growth rate without addition of oxygen or halogen is 260 ℃.

  15. Atomic layer deposition of nanolaminate oxide films on Si

    Science.gov (United States)

    Tallarida, M.; Weisheit, M.; Kolanek, K.; Michling, M.; Engelmann, H. J.; Schmeisser, D.

    2011-11-01

    Among the methods for depositing thin films, atomic layer deposition is unique for its capability of growing conformal thin films of compounds with a control of composition and thickness at the atomic level. The conformal growth of thin films can be of particular interest for covering nanostructures since it assures the homogeneous growth of the ALD film in all directions, independent of the position of the sample with respect to the incoming precursor flow. Here we describe the technique for growing the HfO2/Al2O3 bilayer on Si substrate and our in situ approach for its investigation by means of synchrotron radiation photoemission. In particular, we study the interface interactions between the two oxides for various thickness compositions ranging from 0.4 to 2.7 nm. We find that the ALD of HfO2 on Si induces the increase of the interfacial SiO2 layer, and a change in the band bending of Si. On the contrary, the ALD of Al2O3 on HfO2 shows negligible interaction between layers as the binding energies of Hf4f, Si2p, and O1s core level peaks and the valence band maximum of HfO2 do not change and the interfacial SiO2 does not increase.

  16. Comparison Between Research-Grade SnO2 and Commercial Available SnO2 for Thin-Film CdTe Solar Cell (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.; Pankow, J.; To, B.; Gessert, T.

    2008-05-01

    A comparison between research-grade, tin-oxide (SnO{sub 2}) thin films and those available from commercial sources is performed. The research-grade SnO{sub 2} film is fabricated at NREL by low-pressure metal-organic chemical vapor deposition. The commercial SnO{sub 2} films are Pilkington Tec 8 and Tec 15 fabricated by atmospheric-pressure chemical vapor deposition. Optical, structural, and compositional analyses are performed. From the optical analysis, an estimation of the current losses due to the SnO{sub 2} layer and glass is provided. Our analysis indicates that the optical properties of commercial SnO{sub 2} could be improved for PV usage.

  17. Luminescent Nanocrystalline Silicon Carbide Thin Film Deposited by Helicon Wave Plasma Enhanced Chemical Vapour Deposition

    Institute of Scientific and Technical Information of China (English)

    LU Wan-bing; YU Wei; WU Li-ping; CUI Shuang-kui; FU Guang-sheng

    2006-01-01

    Hydrogenated nanocrystalline silicon carbide (SiC) thin films were deposited on the single-crystal silicon substrate using the helicon wave plasma enhanced chemical vapor deposition (HW-PECVD) technique. The influences of magnetic field and hydrogen dilution ratio on the structures of SiC thin film were investigated with the atomic force microscopy (AFM), the Fourier transform infrared absorption (FTIR) and the transmission electron microscopy (TEM). The results indicate that the high plasma activity of the helicon wave mode proves to be a key factor to grow crystalline SiC thin films at a relative low substrate temperature. Also, the decrease in the grain sizes from the level of microcrystalline to that of nanocrystalline can be achieved by increasing the hydrogen dilution ratios. Transmission electron microscopy measurements reveal that the size of most nanocrystals in the film deposited under the higher hydrogen dilution ratios is smaller than the doubled Bohr radius of 3C-SiC (approximately 5.4 nm), and the light emission measurements also show a strong blue photoluminescence at the room temperature, which is considered to be caused by the quantum confinement effect of small-sized SiC nanocrystals.

  18. Deposition and Tribological Properties of Sulfur-Doped DLC Films Deposited by PBII Method

    Directory of Open Access Journals (Sweden)

    Nutthanun Moolsradoo

    2010-01-01

    Full Text Available Sulfur-doped diamond-like carbon films (S-DLC fabricated from C2H2 and SF6 mixtures were used to study the effects of sulfur content and negative pulse bias voltage on the deposition and tribological properties of films prepared by plasma-based ion implantation (PBII. The structure and relative concentration of the films were analyzed by Raman spectroscopy and Auger electron spectroscopy. Hardness and elastic modulus of films were measured by nanoindentation hardness testing. Tribological characteristics of films were performed using a ball-on-disk friction tester. The results indicate that with the increasing sulfur content, the hardness and elastic modulus decrease. Additionally, by changing the negative pulse bias voltage from 0 kV to −5 kV, the hardness and elastic modulus increase, while the friction coefficient and specific wear rate tends to decrease. Moreover, at a negative pulse bias voltage of −5 kV and flow-rate ratio of 1 : 2, there is considerable improvement in friction coefficient of 0.05 under ambient air is due to the formation of a transfer films on the interface. The decrease in the friction coefficient of films doped with 4.9 at.% sulfur is greater under high vacuum (0.03 than under ambient air (>0.1.

  19. In-situ CdS/CdTe Heterojuntions Deposited by Pulsed Laser Deposition

    KAUST Repository

    Avila-Avendano, Jesus

    2016-04-09

    In this paper pulsed laser deposition (PLD) methods are used to study p-n CdTe/CdS heterojunctions fabricated in-situ. In-situ film deposition allows higher quality p-n interfaces by minimizing spurious contamination from the atmosphere. Morphologic and structural analyses were carried for CdTe films deposited on various substrates and different deposition conditions. The electrical characteristics and performance of the resulting p-n heterojunctions were studied as function of substrate and post-deposition anneal temperature. In-situ growth results on diodes with a rectification factor of ~ 105, an ideality factor < 2, and a reverse saturation current ~ 10-8 A. The carrier concentration in the CdTe film was in the range of ~ 1015 cm-3, as measured by C-V methods. The possible impact of sulfur diffusion from the CdS into the CdTe film is also investigated using High Resolution Rutherford Back-Scattering.

  20. How grain boundaries affect the efficiency of poly-CdTe solar-cells: A fundamental atomic-scale study of grain boundary dislocation cores using CdTe bi-crystal thin films.

    Energy Technology Data Exchange (ETDEWEB)

    Klie, Robert [Univ. of Illinois, Chicago, IL (United States)

    2016-10-25

    It is now widely accepted that grain boundaries in poly-crystalline CdTe thin film devices have a detrimental effect on the minority carrier lifetimes, the open circuit voltage and therefore the overall solar-cell performance. The goal of this project was to develop a fundamental understanding of the role of grain boundaries in CdTe on the carrier life-time, open-circuit voltage, Voc, and the diffusion of impurities. To achieve this goal, i) CdTe bi-crystals were fabricated with various misorientation angels, ii) the atomic- and electronic structures of the grain boundaries were characterized using scanning transmission electron microscopy (STEM), and iii) first-principles density functional theory modeling was performed on the structures determined by STEM to predict the grain boundary potential. The transport properties and minority carrier lifetimes of the bi-crystal grain boundaries were measured using a variety of approaches, including TRPL, and provided feedback to the characterization and modeling effort about the effectiveness of the proposed models.

  1. Scaling in film growth by pulsed laser deposition and modulated beam deposition.

    Science.gov (United States)

    Lee, Sang Bub

    2011-04-01

    The scalings in film growth by pulsed laser deposition (PLD) and modulated beam deposition (MBD) were investigated by Monte Carlo simulations. In PLD, an atomic pulse beam with a period t(0) were deposited instantaneously on a substrate, whereas in MBD, adatoms were deposited during a short time interval t(1) (0≤t(1)≤t(0)) within each period. If t(1)=0, MBD will be identical to PLD and, if t(1)=t(0), MBD will become usual molecular beam epitaxy (MBE). Specifically, logarithmic scaling was investigated for the nucleation density reported for PLD, and the scaling of island density was studied regarding the growth for 0MBE growth was observed as t(1) increased. The phase diagram was also presented.

  2. Studies of Structure,Composition and Photoelectric Properties of CdTe Thin Film Grown by Vacuum Sublimation%真空热蒸发碲化镉薄膜的结构组成和光电性能研究

    Institute of Scientific and Technical Information of China (English)

    张溪文; 韩高荣

    2001-01-01

    Microstructure,chemical composition,film growth mechanism and photoelectric properties of CdTe films grown by vacuum sublimation were studied.Through analysis of XRD,TEM,XPS and photo/dark conductivity,the relation between substrate temperature and microstructure,composition and film oxidation was described systematically.The substrate temperature is the key parameter to decide the film quality.150 ℃ is confirmed to be the most suitable substrate temperature to obtain the film with the best photoelectric and physical properties.Furthermore,the mechanisms of film oxidation and film deposition were preliminarily discussed.%研究了真空热蒸发制备CdTe薄膜的光电性能以及微结构、化学组成和成膜机理。通过X射线衍射、透射电镜电子衍射、X光电子能谱和光、暗电导测试等分析手段,系统表述了薄膜的组成、结构、表面氧化与真空热蒸发工艺的关系。指出基板温度是决定CdTe薄膜组成和结构的关键参数,150 ℃左右制备的CdTe薄膜具有最佳光电性能和成膜质量。另外,对CdTe薄膜的氧化机制和成膜机理也进行了初步探讨。

  3. P-type thin films transistors with solution-deposited lead sulfide films as semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Carrillo-Castillo, A.; Salas-Villasenor, A.; Mejia, I. [Department of Materials Science and Engineering, The University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Aguirre-Tostado, S. [Centro de Investigacion en Materiales Avanzados, S. C. Alianza Norte 202, Parque de Investigacion e Innovacion Tecnologica, Apodaca, Nuevo Leon, C.P. 666000 (Mexico); Gnade, B.E. [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States); Quevedo-Lopez, M.A., E-mail: mxq071000@utdallas.edu [Department of Materials Science and Engineering, University of Texas at Dallas. 800 West Campbell Rd, Richardson, TX 75083 (United States)

    2012-01-31

    In this paper we demonstrate p-type thin film transistors fabricated with lead sulfide (PbS) as semiconductor deposited by chemical bath deposition methods. Crystallinity and morphology of the resulting PbS films were characterized using X-ray diffraction, atomic force microscopy and scanning electron microscopy. Devices were fabricated using photolithographic processes in a bottom gate configuration with Au as source and drain top contacts. Field effect mobility for as-fabricated devices was {approx} 0.09 cm{sup 2} V{sup -1} s{sup -1} whereas the mobility for devices annealed at 150 Degree-Sign C/h in forming gas increased up to {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Besides the thermal annealing, the entire fabrications process was maintained below 100 Degree-Sign C. The electrical performance of the PbS-thin film transistors was studied before and after the 150 Degree-Sign C anneal as well as a function of the PbS active layer thicknesses. - Highlights: Black-Right-Pointing-Pointer Thin film transistors with PbS as semiconductor deposited by chemical bath deposition. Black-Right-Pointing-Pointer Photolithography-based thin film transistors with PbS films at low temperatures. Black-Right-Pointing-Pointer Electron mobility for anneal-PbS devices of {approx} 0.14 cm{sup 2} V{sup -1} s{sup -1}. Black-Right-Pointing-Pointer Highest mobility reported in thin film transistors with PbS as the semiconductor.

  4. The Effects of Two Thick Film Deposition Methods on Tin Dioxide Gas Sensor Performance

    OpenAIRE

    Bakrania, Smitesh D.; Margaret S. Wooldridge

    2009-01-01

    This work demonstrates the variability in performance between SnO2 thick film gas sensors prepared using two types of film deposition methods. SnO2 powders were deposited on sensor platforms with and without the use of binders. Three commonly utilized binder recipes were investigated, and a new binder-less deposition procedure was developed and characterized. The binder recipes yielded sensors with poor film uniformity and poor structural integrity, compared to the binder-less deposition meth...

  5. Atomic layer deposition ultrathin film origami using focused ion beams

    Science.gov (United States)

    Supekar, O. D.; Brown, J. J.; Eigenfeld, N. T.; Gertsch, J. C.; Bright, V. M.

    2016-12-01

    Focused ion beam (FIB) micromachining is a powerful tool for maskless lithography and in recent years FIB has been explored as a tool for strain engineering. Ion beam induced deformation can be utilized as a means for folding freestanding thin films into complex 3D structures. FIB of high energy gallium (Ga+) ions induces stress by generation of dislocations and ion implantation within material layers, which create creases or folds upon mechanical relaxation enabled by motion of the material layers. One limitation on such processing is the ability to fabricate flat freestanding thin film structures. This capability is limited by the residual stresses formed during processing and fabrication of the films, which can result in initial curvature and deformation of films upon release from a sacrificial fabrication layer. This paper demonstrates folding in freestanding ultrathin films (1:1000) by ion-induced stress relaxation. The ultrathin flat structures are fabricated using atomic layer deposition on sacrificial polyimide. We have demonstrated vertical folding with 30 keV Ga+ ions in structures with lateral dimensions varying from 10 to 50 μm.

  6. Resonant Infrared Matrix Assisted Pulsed Laser Deposition of Polymers: Improving the Morphology of As-Deposited Films

    Science.gov (United States)

    Bubb, Daniel; Papantonakis, Michael; Collins, Brian; Brookes, Elijah; Wood, Joshua; Gurudas, Ullas

    2008-03-01

    Resonant infrared matrix assisted pulsed laser deposition has been used to deposit thin films of PMMA, a widely used industrial polymer. This technique is similar to conventional pulsed laser deposition, except that the polymer to be deposited is dissolved in a solvent and the solution is frozen before ablation in a vacuum chamber. The laser wavelength is absorbed by a vibrational band in the frozen matrix. The polymer lands on the substrate to form a film, while the solvent is pumped away. Our preliminary results show that the surface roughness of the as-deposited films depends strongly on the differential solubility radius, as defined by Hansen solubility parameters of the solvent and the solubility radius of the polymer. Our results will be compared with computational and experimental studies of the same polymer using a KrF (248 nm) laser. The ejection mechanism will be discussed as well as the implications of these results for the deposition of smooth high quality films.

  7. Pulsed laser deposition of fluoride glass thin films

    Science.gov (United States)

    Ganser, Dimitri; Gottmann, Jens; Mackens, Uwe; Weichmann, Ulrich

    2010-11-01

    The development of integrated waveguide lasers for different applications such as marking, illumination or medical technology has become highly desirable. Diode pumped planar waveguide lasers emitting in the green visible spectral range, e.g. thin films from praseodymium doped fluorozirconate glass matrix (called ZBLAN, owing to the main components ZrF 4, BaF 2, LaF 3, AlF 3 and NaF) as the active material pumped by a blue laser diode, have aroused great interest. In this work we have investigated the deposition of Pr:ZBLAN thin films using pulsed laser radiation of λ = 193 and λ = 248 nm. The deposition has been carried out on MgF 2 single crystal substrates in a vacuum chamber by varying both processing gas pressure and energy fluence. The existence of an absorption line at 210 nm in Pr:ZBLAN leads to absorption and radiative relaxation of the absorbed laser energy of λ = 193 nm preventing the evaporation of target material. The deposited thin films consist of solidified and molten droplets and irregular particulates only. Furthermore, X-ray radiation has been applied to fluoride glass targets to enhance the absorption in the UV spectral region and to investigate the deposition of X-ray treated targets applying laser radiation of λ = 248 nm. It has been shown that induced F-centres near the target surface are not thermally stable and can be easily ablated. Therefore, λ = 248 nm is not suitable for evaporation of Pr:ZBLAN.

  8. Pulsed laser deposition of fluoride glass thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ganser, Dimitri, E-mail: dimitri.ganser@llt.rwth-aachen.de [Chair for Laser Technology LLT, RWTH Aachen University, Steinbachstr. 15, D-52074 Aachen (Germany); Gottmann, Jens [Chair for Laser Technology LLT, RWTH Aachen University, Steinbachstr. 15, D-52074 Aachen (Germany); Mackens, Uwe; Weichmann, Ulrich [Philips Research Laboratories, Weisshausstrasse 2, D-52066 Aachen (Germany)

    2010-11-15

    The development of integrated waveguide lasers for different applications such as marking, illumination or medical technology has become highly desirable. Diode pumped planar waveguide lasers emitting in the green visible spectral range, e.g. thin films from praseodymium doped fluorozirconate glass matrix (called ZBLAN, owing to the main components ZrF{sub 4}, BaF{sub 2}, LaF{sub 3}, AlF{sub 3} and NaF) as the active material pumped by a blue laser diode, have aroused great interest. In this work we have investigated the deposition of Pr:ZBLAN thin films using pulsed laser radiation of {lambda} = 193 and {lambda} = 248 nm. The deposition has been carried out on MgF{sub 2} single crystal substrates in a vacuum chamber by varying both processing gas pressure and energy fluence. The existence of an absorption line at 210 nm in Pr:ZBLAN leads to absorption and radiative relaxation of the absorbed laser energy of {lambda} = 193 nm preventing the evaporation of target material. The deposited thin films consist of solidified and molten droplets and irregular particulates only. Furthermore, X-ray radiation has been applied to fluoride glass targets to enhance the absorption in the UV spectral region and to investigate the deposition of X-ray treated targets applying laser radiation of {lambda} 248 nm. It has been shown that induced F-centres near the target surface are not thermally stable and can be easily ablated. Therefore, {lambda} = 248 nm is not suitable for evaporation of Pr:ZBLAN.

  9. Innovative sputtering techniques for CIS and CdTe submodule fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, J.M.; Misra, M.S.; Lanning, B. (Martin Marietta Aerospace, Denver, CO (United States). Astronautics Group)

    1993-03-01

    This report describes work done during Phase 1 of the subject subcontract. The subcontract was designed to study innovative deposition techniques, such as the rotating cylindrical magnetron sputtering system and electrodeposition for large-area, low-cost copper indium diselenide (CIS) and cadmium telluride (CdTe) devices. A key issue for photovoltaics (PV) in terrestrial and future space applications is producibility, particularly for applications using a large quantity of PV. Among the concerns for fabrication of polycrystalline thin-film PV, such as CIS and CdTe, are production volume, cost, and minimization of waste. Both rotating cylindrical magnetron (C-Mag[trademark]) sputtering and electrodeposition have tremendous potential for the fabrication of polycrystalline thin-film PV due to scaleability, efficient utilization of source materials, and inherently higher deposition rates. In the case of sputtering, the unique geometry of the C-Mae facilitates innovative cosputtering and reactive sputtering that could lead to greater throughput reduced health and safety risks, and, ultimately, lower fabrication cost. Electrodeposited films appear to be adherent and comparable with low-cost fabrication techniques. Phase I involved the initial film and device fabrication using the two techniques mentioned herein. Devices were tested by both internal facilities, as well as NREL and ISET.

  10. Direct current magnetron sputter-deposited ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hoon, Jian-Wei [Faculty of Engineering, Multimedia University, Persiaran Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Chan, Kah-Yoong, E-mail: kychan@mmu.edu.my [Faculty of Engineering, Multimedia University, Persiaran Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Krishnasamy, Jegenathan; Tou, Teck-Yong [Faculty of Engineering, Multimedia University, Persiaran Multimedia, 63100 Cyberjaya, Selangor (Malaysia); Knipp, Dietmar [School of Engineering and Science, Jacobs University Bremen, 28759 Bremen (Germany)

    2011-01-15

    Zinc oxide (ZnO) is a very promising electronic material for emerging transparent large-area electronic applications including thin-film sensors, transistors and solar cells. We fabricated ZnO thin films by employing direct current (DC) magnetron sputtering deposition technique. ZnO films with different thicknesses ranging from 150 nm to 750 nm were deposited on glass substrates. The deposition pressure and the substrate temperature were varied from 12 mTorr to 25 mTorr, and from room temperature to 450 deg. C, respectively. The influence of the film thickness, deposition pressure and the substrate temperature on structural and optical properties of the ZnO films was investigated using atomic force microscopy (AFM) and ultraviolet-visible (UV-Vis) spectrometer. The experimental results reveal that the film thickness, deposition pressure and the substrate temperature play significant role in the structural formation and the optical properties of the deposited ZnO thin films.

  11. Effects of deposition parameters on the properties of VO2 thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Lixia; LI Jianping; GAO Xiaoguang; HE Xiuli

    2006-01-01

    The vanadium oxide thin films are deposited for microbolometers by radio frequency reactive sputtering method at room temperature. The effects of the oxygen partial pressure on the deposition rate, electrical properties and compositions of the films are discussed. The as-deposited VOx thin films with x value of nearly 2 are deposited by adjusting the oxygen partial pressure. After oxidation annealing of these films in air, the VO2 films with high temperature coefficients of resistivity (about - 49%/℃ ) and low resistivity can be obtained. The square resistances of the films are in the range of 100 kΩ/squ-300 kΩ/squ. All films are deposited at room temperature and annealed at 400℃, in which the compatibility between VOx deposition process and MEMS (micro electromechanical systems) is greatly improved.

  12. Tribological Properties of DLC Film Prepared by C + Ion Beam-assisted Deposition (IBAD)

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    C + ion beam-assisted deposition was utilized to prepare deposit diamond-like carbon (DLC) film.With the help of a series of experiments such as Raman spectroscopy, FT- IR spectroscopy, AFM and nanoindentation, the DLC film has been recognized as hydrogenated DLC film and its tribological properties have been evaluated.The ball-on-disc testing results show that the hardness and the tribological properties of the DLC film produced by C + ion beam-assisted deposition are improved significandy.DLC film produced by C+ ion beam-assisted deposition is positive to have a prosperous tribological application in the near future.

  13. Atomistic study of deposition process of Al thin film on Cu substrate

    Energy Technology Data Exchange (ETDEWEB)

    Cao Yongzhi, E-mail: yzcaohit@gmail.com [Center for Precision Engineering, Harbin Institute of Technology, Harbin (China); Zhang Junjie; Sun Tao; Yan Yongda; Yu Fuli [Center for Precision Engineering, Harbin Institute of Technology, Harbin (China)

    2010-08-01

    In this paper we report molecular dynamics based atomistic simulations of deposition process of Al atoms onto Cu substrate and following nanoindentation process on that nanostructured material. Effects of incident energy on the morphology of deposited thin film and mechanical property of this nanostructured material are emphasized. The results reveal that the morphology of growing film is layer-by-layer-like at incident energy of 0.1-10 eV. The epitaxy mode of film growth is observed at incident energy below 1 eV, but film-mixing mode commences when incident energy increase to 10 eV accompanying with increased disorder of film structure, which improves quality of deposited thin film. Following indentation studies indicate deposited thin films pose lower stiffness than single crystal Al due to considerable amount of defects existed in them, but Cu substrate is strengthened by the interface generated from lattice mismatch between deposited Al thin film and Cu substrate.

  14. Substrate heating measurements in pulsed ion beam film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Olson, J.C.; Davis, H.A.; Rej, D.J.; Waganaar, W.J. [Los Alamos National Lab., NM (United States); Tallant, D.R. [Cornell Univ., Ithaca, NY (United States). Materials Science and Engineering Dept.; Thompson, M.O. [Sandia National Labs., Albuquerque, NM (United States)

    1995-05-01

    Diamond-like Carbon (DLC) films have been deposited at Los Alamos National Laboratory by pulsed ion beam ablation of graphite targets. The targets were illuminated by an intense beam of hydrogen, carbon, and oxygen ions at a fluence of 15-45 J/cm{sup 2}. Ion energies were on the order of 350 keV, with beam current rising to 35 kA over a 400 ns ion current pulse. Raman spectra of the deposited films indicate an increasing ratio of sp{sup 3} to sp{sup 2} bonding as the substrate is moved further away from the target and further off the target normal. Using a thin film platinum resistor at varying positions, we have measured the heating of the substrate surface due to the kinetic energy and heat of condensation of the ablated material. This information is used to determine if substrate heating is responsible for the lack of DLC in positions close to the target and near the target normal. Latest data and analysis will be presented.

  15. Controlled Mechanical Cracking of Metal Films Deposited on Polydimethylsiloxane (PDMS

    Directory of Open Access Journals (Sweden)

    Andreas Polywka

    2016-09-01

    Full Text Available Stretchable large area electronics conform to arbitrarily-shaped 3D surfaces and enables comfortable contact to the human skin and other biological tissue. There are approaches allowing for large area thin films to be stretched by tens of percent without cracking. The approach presented here does not prevent cracking, rather it aims to precisely control the crack positions and their orientation. For this purpose, the polydimethylsiloxane (PDMS is hardened by exposure to ultraviolet radiation (172 nm through an exposure mask. Only well-defined patterns are kept untreated. With these soft islands cracks at the hardened surface can be controlled in terms of starting position, direction and end position. This approach is first investigated at the hardened PDMS surface itself. It is then applied to conductive silver films deposited from the liquid phase. It is found that statistical (uncontrolled cracking of the silver films can be avoided at strain below 35%. This enables metal interconnects to be integrated into stretchable networks. The combination of controlled cracks with wrinkling enables interconnects that are stretchable in arbitrary and changing directions. The deposition and patterning does not involve vacuum processing, photolithography, or solvents.

  16. Characterization of Bi-Catalyzed Nanocrystalline CdTe Thin Films Prepared by Close Spaced Sublimation%近距离升华法制备Bi催化纳米晶CdTe薄膜的表征

    Institute of Scientific and Technical Information of China (English)

    李锦; 尚飞; 郑毓峰; 孙言飞; 简基康; 吴荣

    2009-01-01

    采用近距离升华法(Close-Spaced-Sublimation,CSS)引入Bi催化剂成功制备出了具有纳米线、近阵列排布的纳米棒等形貌的纳米晶CdTe薄膜.并利用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外可见分光光度计等研究了薄膜的结构、表面形貌和光学性能.讨论了CdTe纳米结构可能的生长机制.%Bi-catalyzed nanocrystalline CdTe films were prepared by close spaced sublimation (CSS) technique successfully.These nanocrystalline CdTe films had surface appearance of nanowires or a similar array arrangement nanorod.The structure,the surface topograph and the optical properties of these films were studied using X-ray diffraction(XRD),scanning electron microscopy(SEM) and ultroviolet-visible (UV-VIS) spectrophotometer.And the possible growth mechanisms of these nanostructures were discussed.

  17. Electroless deposition, post annealing and characterization of nickel films on silicon

    Indian Academy of Sciences (India)

    Subir Sabharwal; Siddharth Palit; R B Tokas; A K Poswal; Sangeeta

    2008-10-01

    Electroless deposition of nickel (EN) films on -type silicon has been investigated under different process conditions. The interface between the film and substrate has been characterized for electrical properties by probing the contact resistances. X-ray diffraction and atomic force microscopy have been performed to obtain information about the structural and morphological details of the films. As a comparative study, nickel films have also been sputter deposited on silicon substrates. An as-deposited electroless film is observed to form non-ohmic contact while in a sputtered film prepared without the application of substrate heating, the formation of metal–insulating–semiconductor type junction is seen.

  18. Pulsed laser deposition growth of FeSb2 films for thermoelectric applications

    DEFF Research Database (Denmark)

    Sun, Ye; Canulescu, Stela; Sun, Peijie;

    2011-01-01

    FeSb2 films were produced in a low-pressure Ar environment by pulsed laser deposition at 355 nm. The influence of growth parameters such as substrate temperature, Ar pressure and deposition time on the growth of FeSb2 films was studied. Nearly phase-pure FeSb2 films with thicknesses of 100–400 nm...

  19. Pulsed laser deposition of permanent magnetic Nd2Fe14B thin films

    NARCIS (Netherlands)

    Geurtsen, A.J.M.; Kools, J.C.S.; Wit, L.; Lodder, J.C.

    1996-01-01

    Pulsed Laser Deposition (PLD) is applied to deposit thin (thickness typically 100 nm) films of Nd2Fe14B. It is shown that films can be grown which have the desired composition and phase. Nd2Fe14B grows with the c-axis along the film normal on 110 Al2O3 single crystal substrates covered with a Ta lay

  20. Pure and Sn-doped ZnO films produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Holmelund, E.; Schou, Jørgen; Tougaard, S.;

    2002-01-01

    A new technique, metronome doping, has been used for doping of films during pulsed laser deposition (PLD). This technique makes it possible to dope continuously during film growth with different concentrations of a dopant in one deposition sequence. Films of pure and doped ZnO have been produced...

  1. Deposition of highly (111)-oriented PZT thin films by using metal organic chemical deposition

    CERN Document Server

    Bu, K H; Choi, D K; Seong, W K; Kim, J D

    1999-01-01

    Lead zirconate titanate (PZT) thin films have been grown on Pt/Ta/SiNx/Si substrates by using metal organic chemical vapor deposition with Pb(C sub 2 H sub 5) sub 4 , Zr(O-t-C sub 4 H sub 9) sub 4 , and Ti(O-i-C sub 3 H sub 7) sub 4 as source materials and O sub 2 as an oxidizing gas. The Zr fraction in the thin films was controlled by varying the flow rate of the Zr source material. The crystal structure and the electrical properties were investigated as functions of the composition. X-ray diffraction analysis showed that at a certain range of Zr fraction, highly (111)-oriented PZT thin films with no pyrochlore phases were deposited. On the other hand, at low Zr fractions, there were peaks from Pb-oxide phases. At high Zr fractions, peaks from pyrochlore phase were seen. The films also showed good electrical properties, such as a high dielectric constant of more than 1200 and a low coercive voltage of 1.35 V.

  2. Properties of HfAlO film deposited by plasma enhanced atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Duo [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Changning Road 865, Shanghai 200050 (China); Cheng, Xinhong, E-mail: xh_cheng@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Changning Road 865, Shanghai 200050 (China); Jia, Tingting; Zheng, Li; Xu, Dawei; Wang, Zhongjian; Xia, Chao; Yu, Yuehui [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-system and Information Technology, Chinese Academy of Sciences, Changning Road 865, Shanghai 200050 (China)

    2013-07-15

    Plasma enhanced atomic layer deposition (PEALD) method can reduce film growing temperature, and allow in situ plasma treatment. In this work, HfAlO and HfO{sub 2} films were deposited with PEALD at 160 °C. Microstructure analysis showed that both films were amorphous after rapid thermal annealing (RTA) treatment, and HfAlO sample showed better interfacial structure than HfO{sub 2}. X-ray photoelectron spectroscopy (XPS) spectra indicated that main component of the interfacial layer of HfAlO sample was Hf–Si–O and Al–Si–O bonds, the valence band offset value between the HfAlO film and Si substrate was calculated to be 2.5 eV. The dominant leakage current mechanism of the samples was Schottky emission at a low electric field (<1.4 MV/cm), and Poole–Frenkel emission mechanism at a higher electric field (>1.4 MV/cm). The equivalent oxide thicknesses (EOT) of the HfAlO samples were 1.0 nm and 1.3 nm, respectively. The density of interface states between dielectric and substrate were calculated to be 1.2 × 10{sup 12} eV{sup −1}cm{sup −2} and 1.3 × 10{sup 12} eV{sup −1}cm{sup −2}, respectively. In comparison with HfO{sub 2} film, HfAlO film has good interfacial structure and electrical performance.

  3. Study of Nanocrystalline Diamond Film Deposited Rapidly by 500 W Excimer Laser

    Institute of Scientific and Technical Information of China (English)

    PENG Hongyan; SHEN Jiajing; YANG Guilong

    2000-01-01

    High quality nanocrystalline diamond film deposited rapidly by an XeCl excimer laser operated at high laser power (500 W) and repetition rate (300~500 Hz) is presented. A high deposition rate, 250 nm/thousand pulses, was obtained. The effects of laser energy fluence and repetition rate on the deposition of diamond film were investigated.

  4. Properties of alumina films by atmospheric pressure metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Corbach, van H.D.; Fransen, T.; Gellings, P.J.

    1994-01-01

    Thin alumina films were deposited at low temperatures (290–420°C) on stainless steel, type AISI 304. The deposition process was carried out in nitrogen by metal-organic chemical vapour deposition using aluminum tri-sec-butoxide. The film properties including the protection of the underlying substrat

  5. The spatial thickness distribution of metal films produced by large area pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, Nini; Schou, Jørgen; Linderoth, Søren

    2007-01-01

    Thin films of metals have been deposited in the large-area Pulsed Laser Deposition (PLD) Facility at Riso National Laboratory. Thin films of Ag and Ni were deposited with laser pulses from an excimer laser at 248 nm with a rectangular beam spot at a fluence of 10 J/cm(2) on glass substrates of 12...

  6. Phase change properties of Ti-Sb-Te thin films deposited by thermal atomic layer deposition

    Science.gov (United States)

    Song, Sannian; Shen, Lanlan; Song, Zhitang; Yao, Dongning; Guo, Tianqi; Li, Le; Liu, Bo; Wu, Liangcai; Cheng, Yan; Ding, Yuqiang; Feng, Songlin

    2016-10-01

    Phase change random access memory (PCM) appears to be the strongest candidate for next-generation high density nonvolatile memory. The fabrication of ultrahigh density PCM depends heavily on the thin film growth technique for the phase changing chalcogenide material. In this study, TiSb2Te4 (TST) thin films were deposited by thermal atomic layer deposition (ALD) method using TiCl4, SbCl3, (Et3Si)2Te as precursors. The threshold voltage for the cell based on thermal ALD-deposited TST is about 2.0 V, which is much lower than that (3.5 V) of the device based on PVD-deposited Ge2Sb2Te5 (GST) with the identical cell architecture. Tests of TST-based PCM cells have demonstrated a fast switching rate of 100 ns. Furthermore, because of the lower melting point and thermal conductivities of TST materials, TST-based PCM cells exhibit 19% reduction of pulse voltages for Reset operation compared with GST-based PCM cells. These results show that thermal ALD is an attractive method for the preparation of phase change materials.

  7. Verification of cell irradiation dose deposition using a radiochromic film

    Energy Technology Data Exchange (ETDEWEB)

    Tomic, N [Department of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, Quebec (Canada); Gosselin, M [Department of Radiation Oncology, Jewish General Hospital, McGill University, Montreal, Quebec (Canada); Wan, Jonathan F [Radiation Oncology Department, McGill University Health Centre, Montreal, Quebec (Canada); Saragovi, Uri [Department of Pharmacology, McGill University, Montreal, Quebec (Canada); Podgorsak, E B [Medical Physics Department, McGill University Health Center, Montreal, Quebec (Canada); Evans, M [Medical Physics Department, McGill University Health Center, Montreal, Quebec (Canada); Devic, S [Medical Physics Department, McGill University Health Center, Montreal, Quebec (Canada)

    2007-06-07

    We describe a technique for the MTT assay that irradiates all cells at once by a combination of couch movement and a step-and-shoot irradiation technique on a linear accelerator with 6 MV and 18 MV photon beams. In two experimental setups, we obtained maximum to minimum dose ranges of 10 for the constant MU/bin (monitor units per bin) setup and 20 for the variable MU/bin technique. The irradiation technique described is dose rate independent and it can be used on any teletherapy irradiation machine. We also employed radiochromic film dosimetry to verify dose delivered in each of the wells within the dish. It is shown that for the lowest doses, relative dose variation within wells reaches a value of 6%. We also demonstrated that the radiochromic film positioned below the 96-well plate does not underestimate dose deposited within each compartment by more than 2% due to the vertical dose gradient.

  8. Verification of cell irradiation dose deposition using a radiochromic film

    Science.gov (United States)

    Tomic, N.; Gosselin, M.; Wan, Jonathan F.; Saragovi, Uri; Podgorsak, E. B.; Evans, M.; Devic, S.

    2007-06-01

    We describe a technique for the MTT assay that irradiates all cells at once by a combination of couch movement and a step-and-shoot irradiation technique on a linear accelerator with 6 MV and 18 MV photon beams. In two experimental setups, we obtained maximum to minimum dose ranges of 10 for the constant MU/bin (monitor units per bin) setup and 20 for the variable MU/bin technique. The irradiation technique described is dose rate independent and it can be used on any teletherapy irradiation machine. We also employed radiochromic film dosimetry to verify dose delivered in each of the wells within the dish. It is shown that for the lowest doses, relative dose variation within wells reaches a value of 6%. We also demonstrated that the radiochromic film positioned below the 96-well plate does not underestimate dose deposited within each compartment by more than 2% due to the vertical dose gradient.

  9. Structural properties of oxygenated amorphous cadmium telluride thin films

    Energy Technology Data Exchange (ETDEWEB)

    El Azhari, M.Y. [Laboratoire de Physique des Solides et des Couches Minces, Marakech (Morocco). Dept. de Physique; Azizan, M. [Laboratoire de Physique des Solides et des Couches Minces, Marakech (Morocco). Dept. de Physique; Bennouna, A. [Laboratoire de Physique des Solides et des Couches Minces, Marakech (Morocco). Dept. de Physique; Outzourhit, A. [Laboratoire de Physique des Solides et des Couches Minces, Marakech (Morocco). Dept. de Physique; Ameziane, E.L. [Laboratoire de Physique des Solides et des Couches Minces, Marakech (Morocco). Dept. de Physique; Brunel, M. [Laboratoire de Cristallographie, CNRS, Grenoble (France)

    1997-02-28

    Cadmium telluride (CdTe) thin films were prepared by diode radio-frequency sputtering from polycrystalline CdTe targets in an atmosphere of argon, nitrogen and oxygen. The layers prepared in the presence of nitrogen gas were amorphous and their oxygen contents increased with the partial pressure of nitrogen. The evolution of the composition of the layers as a function of the nitrogen partial pressure during deposition was followed by X-ray photoelectron spectroscopy. It is found that the oxygen is bound to both tellurium and cadmium atoms. The surface of the CdTe thin films was also studied as a function of their exposure time to a plasma containing a mixture of nitrogen and oxygen. It is found that the oxygen contents of the surface increases with increased exposure time. Also, this exposure resulted in an increase of the oxide thickness and a net decrease in the surface roughness of the films. (orig.)

  10. Photoluminescence and Electroluminescence Properties of CdTe Nanoparticles in Conjugated Polymer Hosts

    Institute of Scientific and Technical Information of China (English)

    GUO, Fengqi; XIE, Puhui

    2009-01-01

    The photoinduced energy transfer process from conjugated polymer (PPE4+) to CdTe nanocrystals was found both in solutions and in thin films by a fluorescence spectroscopic technique. Films of PPE4+ blended with CdTe-2 nanocrystals were formed by an electrostatic layer-by-layer assembly technique. Light emitting diodes were fabricated using CdTe-2 as an emitter in PPE4+ host. PPE4+ works as a molecular wire in the energy transfer process from the polymer to the CdTe-2 nanocrystals.

  11. Comparison of the properties of Pb thin films deposited on Nb substrate using thermal evaporation and pulsed laser deposition techniques

    Energy Technology Data Exchange (ETDEWEB)

    Perrone, A., E-mail: alessio.perrone@unisalento.it [Università del Salento, Dipartimento di Matematica e Fisica “E. De Giorgi”, 73100 Lecce (Italy); INFN-Istituto Nazionale di Fisica Nucleare e Università del Salento, 73100 Lecce (Italy); Gontad, F. [INFN-Istituto Nazionale di Fisica Nucleare e Università del Salento, 73100 Lecce (Italy); Lorusso, A.; Di Giulio, M. [Università del Salento, Dipartimento di Matematica e Fisica “E. De Giorgi”, 73100 Lecce (Italy); Broitman, E. [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-581 83 Linköping (Sweden); Ferrario, M. [Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare, 00044 Frascati (Italy)

    2013-11-21

    Pb thin films were prepared at room temperature and in high vacuum by thermal evaporation and pulsed laser deposition techniques. Films deposited by both the techniques were investigated by scanning electron microscopy to determine their surface topology. The structure of the films was studied by X-ray diffraction in θ–2θ geometry. The photoelectron performances in terms of quantum efficiency were deduced by a high vacuum photodiode cell before and after laser cleaning procedures. Relatively high quantum efficiency (>10{sup −5}) was obtained for all the deposited films, comparable to that of corresponding bulk. Finally, film to substrate adhesion was also evaluated using the Daimler–Benz Rockwell-C adhesion test method. Weak and strong points of these two competitive techniques are illustrated and discussed. -- Highlights: •Comparison of Pb thin films deposited on Nb substrate by thermal evaporation and pulsed laser deposition (PLD). •Photoelectron performances of Pb thin films. •Good quality of adhesion strength of Pb films deposited by PLD.

  12. Dependence of electro-optical properties on the deposition conditions of chemical bath deposited CdS thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dona, J.M.; Herrero, J. [CIEMAT, Madrid (Spain). Inst. de Energias Renovables

    1997-11-01

    Lately, there has been a sharp increase in the publication of papers on chemical bath deposition of CdS thin films and related materials due to successful results obtained using this method to fabricate CdS thin-film buffer layers for CuInSe{sub 2}- and CdTe-based polycrystalline thin-film solar cells. Generally, these papers focus on previously proposed methods of studying film characteristics without a systematic study of the influence of deposition conditions on film characteristics. In this paper the authors present an exhaustive study of the chemical bath-deposited CdS thin films electro-optical properties dependence on deposition variables. The authors propose not only a set of conditions for obtaining CdS thin films by this method but additionally, suitable deposition process conditions for certain application requirements, such as buffer layers for thin-film solar cells. The observed electro-optical characteristics dependence on the deposition variables corroborates the chemical mechanism that they proposed previously for this process.

  13. A Comparison between Thin-Film Transistors Deposited by Hot-Wire Chemical Vapor Deposition and PECVD

    Directory of Open Access Journals (Sweden)

    Meysam Zarchi

    2015-03-01

    Full Text Available The effect of new growth techniques on the mobility and stability of amorphous silicon (a-Si:H thin film transistors (TFTs has been studied. It was suggested that the key parameter controlling the field-effect mobility and stability is the intrinsic stress in the a-Si:H layer. Amorphous and microcrystalline silicon films were deposited by radiofrequency plasma enhanced chemical vapor deposition (RF-PECVD and hot-wire chemical vapor deposition (HW-CVD at 100 ºC and 25 ºC. Structural properties of these films were measured by Raman Spectroscopy. Electronic properties were measured by dark conductivity, σd, and photoconductivity, σph. For amorphous silicon films deposited by RF-PECVD on PET, photosensitivity's of >105 were obtained at both 100 º C and 25 ºC. For amorphous silicon films deposited by HW-CVD, a photosensitivity of > 105 was obtained at 100 ºC. Microcrystalline silicon films deposited by HW-CVD at 95% hydrogen dilution show σph~ 10-4 Ω-1cm-1, while maintaining a photosensitivity of ~102 at both 100 ºC and 25 ºC. Microcrystalline silicon films with a large crystalline fraction (> 50% can be deposited by HW-CVD all the way down to room temperature.

  14. Mobility activation in thermally deposited CdSe thin films

    Indian Academy of Sciences (India)

    Kangkan Sarmah; Ranjan Sarma

    2009-08-01

    Effect of illumination on mobility has been studied from the photocurrent decay characteristics of thermally evaporated CdSe thin films deposited on suitably cleaned glass substrate held at elevated substrate temperatures. The study indicates that the mobilities of the carriers of different trap levels are activated due to the energy of incident illumination, which results in the existence of two distinct trap levels. In each trap depth the energy of the trap increases linearly. It infers that there is a linear distribution of traps of different energies below the conduction band.

  15. Growth of Ge films by cluster beam deposition

    CERN Document Server

    Xu, J L; Feng, J Y

    2002-01-01

    Ge epitaxial layers with reasonable quality were grown on the Si(1 1 1) substrates by cluster beam deposition (CBD) process. The growth temperature plays a dominant role in the epitaxial growth of Ge films. The substrate temperature for epitaxial growth is about 500 deg. C, which is lower than the reported critical temperature of Ge epitaxial growth by MBE and CVD. A stress induced phase transition of Ge lattice from cubic to tetragonal is also observed in the CBD process, and the mechanism is discussed.

  16. Competing magnetic anisotropies in obliquely deposited thin permalloy film

    Energy Technology Data Exchange (ETDEWEB)

    Belyaev, B.A. [Siberian Federal University, 79, pr. Svobodnyi, Krasnoyarsk 660041 (Russian Federation); Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, 50/38, Akademgorodok, Krasnoyarsk 660036 (Russian Federation); Reshetnev Siberian State Aerospace University, 31, pr. Imeni Gazety “Krasnoyarskii Rabochii”, Krasnoyarsk 660014 (Russian Federation); Izotov, A.V. [Siberian Federal University, 79, pr. Svobodnyi, Krasnoyarsk 660041 (Russian Federation); Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, 50/38, Akademgorodok, Krasnoyarsk 660036 (Russian Federation); Solovev, P.N., E-mail: platon.solovev@gmail.com [Siberian Federal University, 79, pr. Svobodnyi, Krasnoyarsk 660041 (Russian Federation)

    2016-01-15

    Distribution of the magnetic anisotropy in thin film prepared by thermal vacuum oblique deposition of permalloy with small off-normal angle of incident in the presence of an external magnetic field has been studied by ferromagnetic resonance technique. On local area of the sample, a mutual compensation of near orthogonal in-plane uniaxial magnetic anisotropies induced by oblique deposition and by applied magnetic field has been found. Moreover, in addition to the uniaxial (twofold) magnetic anisotropy, fourfold and sixfold magnetic anisotropies have been observed in the sample. To explain the obtained high-order anisotropies, we assumed that the sample has exchange coupled adjacent regions or phases with different parameters of magnetic anisotropy. The results of the micromagnetic analysis of a two-layer model of the sample confirm the hypothesis.

  17. Nano-oxide thin films deposited via atomic layer deposition on microchannel plates.

    Science.gov (United States)

    Yan, Baojun; Liu, Shulin; Heng, Yuekun

    2015-01-01

    Microchannel plate (MCP) as a key part is a kind of electron multiplied device applied in many scientific fields. Oxide thin films such as zinc oxide doped with aluminum oxide (ZnO:Al2O3) as conductive layer and pure aluminum oxide (Al2O3) as secondary electron emission (SEE) layer were prepared in the pores of MCP via atomic layer deposition (ALD) which is a method that can precisely control thin film thickness on a substrate with a high aspect ratio structure. In this paper, nano-oxide thin films ZnO:Al2O3 and Al2O3 were prepared onto varied kinds of substrates by ALD technique, and the morphology, element distribution, structure, and surface chemical states of samples were systematically investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS), respectively. Finally, electrical properties of an MCP device as a function of nano-oxide thin film thickness were firstly studied, and the electrical measurement results showed that the average gain of MCP was greater than 2,000 at DC 800 V with nano-oxide thin film thickness approximately 122 nm. During electrical measurement, current jitter was observed, and possible reasons were preliminarily proposed to explain the observed experimental phenomenon.

  18. Mechanical Properties and Thermal Stability of TiN/Ta Multilayer Film Deposited by Ion Beam Assisted Deposition

    Directory of Open Access Journals (Sweden)

    Hongfei Shang

    2014-01-01

    Full Text Available TiN/Ta multilayer film with a modulation period of 5.6 nm and modulation ratio of 1 : 1 was produced by ion beam assisted deposition. Microstructure of the as-deposited TiN/Ta multilayer film was observed by transmission electron microscopy and mechanical properties were investigated. Residual stress in the TiN/Ta multilayer film was about 72% of that of a TiN monolayer film with equivalent thickness deposited under the same conditions. Partial residual stress was released in the Ta sublayers during deposition, which led to the decrease of the residual stress of the TiN/Ta multilayer film. Nanohardness (H of the TiN/Ta multilayer film was 24 GPa, 14% higher than that of the TiN monolayer film. It is suggested that the increase of the nanohardness is due to the introduction of the Ta layers which restrained the growth of TiN crystal and led to the decrease of the grain size. A significant increase (3.5 times of the H3/E2 (E elastic modulus value indicated that the TiN/Ta multilayer film has higher elasticity than the TiN monolayer film. The Lc (critical load in nano-scratch test value of the TiN monolayer film was 45 mN, which was far lower than that of the TiN/Ta multilayer film (around 75 mN. Results of the indentation test showed a higher fracture toughnes