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Sample records for se thin films

  1. Structural characterization of vacuum evaporated ZnSe thin films

    Indian Academy of Sciences (India)

    The lattice parameter, grain size, average internal stress, microstrain, dislocation density and degree of pre- ferred orientation in the film are calculated and correlated with Ts. Keywords. ZnSe thin films; X-ray diffraction; average internal stress; microstrain; dislocation density. 1. Introduction. Thin films of ZnSe has attracted ...

  2. Photoelectrochemical (PEC) studies on CdSe thin films ...

    Indian Academy of Sciences (India)

    TECS

    Thin films of CdSe were deposited by potentiostatic mode on different substrates such as ... trodeposited from aqueous acidic baths, but very few ... washed with liquid detergent (labolene) followed by ul- .... increases the ionic mobilities and hence the conductivity ... A PEC cell of configuration, CdSe/1 M polysulphide/.

  3. One-step synthesis of PbSe-ZnSe composite thin film

    Directory of Open Access Journals (Sweden)

    Abe Seishi

    2011-01-01

    Full Text Available Abstract This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package.

  4. 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).

  5. ZnSe thin films by chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Lokhande, C.D.; Patil, P.S.; Tributsch, H. [Hahn-Meitner-Institute, Bereich Physikalische Chemie, Abt. CS, Glienicker Strasse-100, D-14109 Berlin (Germany); Ennaoui, A. [Hahn-Meitner-Institute, Bereich Physikalische Chemie, Abt. CG, Glienicker Strasse-100, D-14109 Berlin (Germany)

    1998-09-04

    The ZnSe thin films have been deposited onto glass substrates by the simple chemical bath deposition method using selenourea as a selenide ion source from an aqueous alkaline medium. The effect of Zn ion concentration, bath temperature and deposition time period on the quality and thickness of ZnSe films has been studied. The ZnSe films have been characterized by XRD, TEM, EDAX, TRMC (time-resolved microwave conductivity), optical absorbance and RBS techniques for their structural, compositional, electronic and optical properties. The as-deposited ZnSe films are found to be amorphous, Zn rich with optical band gap, Eg, equal to 2.9 eV

  6. Mobility activation in thermally deposited CdSe thin films

    Indian Academy of Sciences (India)

    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 ...

  7. Thermoelectric prospects of chemically deposited PbSe and SnSe thin films

    Science.gov (United States)

    Nair, P. K.; Martínez, Ana Karen; Rosa García Angelmo, Ana; Barrios Salgado, Enue; Nair, M. T. S.

    2018-03-01

    Thin films of PbSe of 400-600 nm in thickness, were obtained via chemical deposition from a solution containing lead nitrate, thiourea and selenosufate. SnSe thin films of 90-180 nm in thickness, were also obtained by chemical deposition from a solution containing selenosulfate. Optical and electrical properties of these thin films were significantly altered by heating them in selenium vapor at 300 °C. Thin film PbSe has a bandgap (Eg) of 1.17 eV (direct gap, forbidden transitions), which decreases to 0.77 eV when it has been heated. Its electrical conductivity (σ) is p-type: 0.18 Ω-1 cm-1 (as-prepared), and 6.4 Ω-1 cm-1 when heated. Thin film SnSe is of orthorhombic crystalline structure which remains stable when heated at 300 °C, but its Eg increases from 1.12 eV (indirect) in as-prepared film to 1.5 eV (direct, forbidden transitions) upon heating. Its electrical conductivity is p-type, which increases from 0.3 Ω-1 cm-1 (as-prepared) to 1 Ω-1 cm-1 when heated (without Se-vapor). When SnSe film is heated at 300 °C in the presence of Se-vapor, they transform to SnSe2, with Eg of 1.5 eV (direct, forbidden) with n-type electrical conductivity, 11 Ω-1 cm-1. The Seebeck coefficient for the PbSe films is: +0.55 mV K-1 (as prepared) and +0.275 mV K-1 (heated); for SnSe films it is: +0.3 mV K-1 (as prepared) and +0.20 mV K-1 (heated); and for SnSe2 film, - 0.35 mV K-1. A five-element PbSe-SnSe2-PbSe-SnSe2-PbSe thermoelectric device demonstrated 50 mV for a temperature difference ΔT = 20 °C (2.5 mV K-1). For SnSe-SnSe2-SnSe-SnSe2-SnSe device, the value is 15 mV for ΔT = 20 °C (0.75 mV K-1). Prospect of these thin films in thermoelectric devices of hybrid materials, in which the coatings may be applied on distinct substrate and geometries is attractive.

  8. Preparation of SnSe thin films by encapsulated selenization

    International Nuclear Information System (INIS)

    Sabar D. Hutagalung; Samsudi Sakrani; Yussof Wahab

    1994-01-01

    Tin selenide thin films were prepared by encapsulated selenization. A stacked layer of evaporated Sn and Se films were annealed in a carbon block at temperatures 100 - 500 degree Celsius for 3 hours. X-ray analysis and SEM (Scanning electron) micrograph results showed that SnSe was initially formed at 150 degree Celsius with crystal size 30.0 nm and reached optimum formation at 200 daximum of 57.4 % yield of 5-decene. Other factors such as reaction temperatures, types of solvent and wt% of rhenium loadings influence the activity of the catalytic system

  9. Preparation and characterization of Zn Se thin films

    CERN Document Server

    Ganchev, M; Stratieva, N; Gremenok, V; Zaretskaya, E; Goncharova, O

    2003-01-01

    Chemical bath deposition technique for preparation of ZnSe thin films is presented. The influence of bath temperature and duration of deposition on film growth and quality has been studied. The effect of post-deposition annealing in different ambient is also discussed. It has been determined that heat treatment removes the oxygen-containing phase from the as-deposited films and improves crystallinity. The optical and electric properties of the deposits show their potential for an alternative buffer layer in chalcopyrite-based solar cells.

  10. Mobility activation in thermally deposited CdSe thin films

    Indian Academy of Sciences (India)

    Administrator

    3. Mobility activation in CdSe thin films. The trap depths were calculated by using the following simple decay law. It = Ioexp(–pt),. (1) where p is the probability of escape of an electron from the trap per second and is given by (Randall and Wilkins 1945) p = S exp (–E/kT),. (2) where E is the trap depth for electrons below the ...

  11. Crystallization kinetics of a-Se, part 4: thin films

    Science.gov (United States)

    Svoboda, Roman; Gutwirth, Jan; Málek, Jiří

    2014-09-01

    Differential scanning calorimetry was used to study the crystallization behaviour of selenium thin films in dependence on film thickness and deposition rate. In the current work, which is the fourth in a sequence of articles dealing with crystallization kinetics of a-Se, the non-isothermal crystallization kinetics was described in terms of the Johnson-Mehl-Avrami nucleation-growth model. Two-dimensional crystallite growth, consistent with the idea of sterically restricted crystallization in a thin layer, was confirmed for all data. It was found that neither the film thickness (tested within the 100-2350 nm range) nor the deposition rate appears to have any significant influence on the crystallization kinetics. However, the higher amount of intrinsic defects possibly produced by a higher deposition rate seems to accelerate the crystallization, shifting it towards lower temperatures. Very good correlation between the results obtained for thin films and those for fine powders was found. Based on the obtained results, interpretations of relevant literature data were made.

  12. Optical band gap study of a-Se and Se-Sb thin films

    International Nuclear Information System (INIS)

    Kaur, Ramandeep; Singh, Palwinder; Thakur, Anup

    2016-01-01

    Amorphous selenium (a-Se) and a-Se_9_5Sb_5 alloy were prepared using melt quenching technique. X-ray diffraction (XRD) pattern confirmed the amorphous nature of the prepared samples. Composition of the prepared samples has been determined using Energy dispersive X-ray fluorescence (EDXRF) technique. Differential thermal analysis (DTA) confirmed the glassy nature of the prepared samples. Thin films of the prepared samples were deposited on glass substrate using thermal evaporation method. Amorphous nature of the deposited films was confirmed using XRD. Optical properties of these films were obtained from the UV-VIS transmission spectra, at normal incidence, over 200-1100 nm spectral range. The optical absorption edge was described by using the model given by the Tauc. Optical band gap of the deposited films was calculated using Tauc plot. Optical characterization showed that average transmission and optical band gap decreased with the addition of antinomy.

  13. Structural and optical properties of electrodeposited culnSe2 thin films for photovoltaic solar cells

    International Nuclear Information System (INIS)

    Guillen, C.; Herrero, J.; Galiano, F.

    1990-01-01

    Optical an structural properties of electrodeposited copper indium diselenide, CulnSe2, thin films were studied for its application in photovoltaic devices. X-ray diffraction patterns showed that thin films were grown in chalcopyrite phase after suitable treatments. Values of Eg for the CulnSe2 thin films showed a dependence on the deposition potential as determined by optical measurements. (Author) 47 refs

  14. Space charge limited conduction in CdSe thin films

    Indian Academy of Sciences (India)

    Unknown

    of trap limited space charge limited conduction (SCLC) at higher voltage. The transition voltage (Vt ) from ohmic to SCLC is found to be quite independent of ambient temperature as well as intensity of illumination. SCLC is explained on the basis of the exponential trap distribution in CdSe films. Trap depths estimated from.

  15. Structural and optical properties of nanocrystalline CdSe and Al:CdSe thin films for photoelectrochemical application

    Energy Technology Data Exchange (ETDEWEB)

    Gawali, Sanjay A. [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur - 416 004 (India); Bhosale, C.H., E-mail: bhosale_ch@yahoo.com [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur - 416 004 (India)

    2011-10-03

    Highlights: {yields} The CdSe and Al:CdSe thin films have been successfully deposited by SPT. {yields} Hexagonal cubic structured CdSe and Al: CdSe thin films are observed. {yields} Large number of fine grains, Uniform and compact growth morphology. {yields} Hydrophilic surface nature. {yields} Al:CdSe have better PEC performance than CdSe. - Abstract: Nanocrystalline CdSe and Al:CdSe semiconductor thin films have been successfully synthesized onto amorphous and FTO glass substrates by spray pyrolysis technique. Aqueous solutions containing precursors of Cd and Se have been used to obtain good quality films. The optimized films have been characterized for their structural, morphological, wettability and optical properties. X-ray diffraction (XRD) studies show that the films are polycrystalline in nature with hexagonal crystal structure. Scanning electron microscopy (SEM) studies show that the film surface is smooth, uniform and compact in nature. Water wettability study reveals that the films are hydrophilic behavior. The formation of CdSe and Al:CdSe thin film were confirmed with the help of FTIR spectroscopy. UV-vis spectrophotometric measurement showed a direct allowed band gap lying in the range 1.673-1.87 eV. Output characteristics were studied by using cell configuration n- CdSe/Al:CdSe |1 M (NaOH + Na{sub 2} + S)|C. An efficient solar cell having a power conversion efficiency of 0.38% at illumination 25 mW cm{sup -2} was fabricated.

  16. The Cu2ZnSnSe4 thin films solar cells synthesized by electrodeposition route

    Science.gov (United States)

    Li, Ji; Ma, Tuteng; Wei, Ming; Liu, Weifeng; Jiang, Guoshun; Zhu, Changfei

    2012-06-01

    An electrodeposition route for preparing Cu2ZnSnSe4 thin films for thin film solar cell absorber layers is demonstrated. The Cu2ZnSnSe4 thin films are prepared by co-electrodeposition Cu-Zn-Sn metallic precursor and subsequently annealing in element selenium atmosphere. The structure, composition and optical properties of the films were investigated by X-ray diffraction (XRD), Raman spectrometry, energy dispersive spectrometry (EDS) and UV-VIS absorption spectroscopy. The Cu2ZnSnSe4 thin film with high crystalline quality was obtained, the band gap and absorption coefficient were 1.0 eV and 10-4 cm-1, which is quite suitable for solar cells fabrication. A solar cell with the structure of ZnO:Al/i-ZnO/CdS/Cu2ZnSnSe4/Mo/glass was fabricated and achieved an conversion efficiency of 1.7%.

  17. AgSbSe2 and AgSb(S,Se)2 thin films for photovoltaic applications

    International Nuclear Information System (INIS)

    Garza, J.G.; Shaji, S.; Rodriguez, A.C.; Das Roy, T.K.; Krishnan, B.

    2011-01-01

    Silver antimony selenide (AgSbSe 2 ) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb 2 S 3 ), silver selenide (Ag 2 Se), selenium (Se) and silver (Ag). Sb 2 S 3 thin film was prepared from a chemical bath containing SbCl 3 and Na 2 S 2 O 3 , Ag 2 Se from a solution containing AgNO 3 and Na 2 SeSO 3 and Se thin films from an acidified solution of Na 2 SeSO 3 , at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 deg. C in vacuum (10 -3 Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe 2 or AgSb(S,Se) 2 depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe 2 /Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed V oc = 435 mV and J sc = 0.08 mA/cm 2 under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe 2 as an absorber material by a non-toxic selenization process is achieved.

  18. AgSbSe{sub 2} and AgSb(S,Se){sub 2} thin films for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Garza, J.G. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Shaji, S. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Facultad de Ingenieria Mecanica y Electrica, CIIDIT - Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Rodriguez, A.C.; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Krishnan, B., E-mail: kbindu_k@yahoo.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Facultad de Ingenieria Mecanica y Electrica, CIIDIT - Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)

    2011-10-01

    Silver antimony selenide (AgSbSe{sub 2}) thin films were prepared by heating sequentially deposited multilayers of antimony sulphide (Sb{sub 2}S{sub 3}), silver selenide (Ag{sub 2}Se), selenium (Se) and silver (Ag). Sb{sub 2}S{sub 3} thin film was prepared from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3}, Ag{sub 2}Se from a solution containing AgNO{sub 3} and Na{sub 2}SeSO{sub 3} and Se thin films from an acidified solution of Na{sub 2}SeSO{sub 3}, at room temperature on glass substrates. Ag thin film was deposited by thermal evaporation. The annealing temperature was 350 deg. C in vacuum (10{sup -3} Torr) for 1 h. X-ray diffraction analysis showed that the thin films formed were polycrystalline AgSbSe{sub 2} or AgSb(S,Se){sub 2} depending on selenium content in the precursor films. Morphology and elemental analysis of these films were done using scanning electron microscopy and energy dispersive X-ray spectroscopy. Optical band gap was evaluated from the UV-visible absorption spectra of these films. Electrical characterizations were done using Hall effect and photocurrent measurements. A photovoltaic structure: glass/ITO/CdS/AgSbSe{sub 2}/Al was formed, in which CdS was deposited by chemical bath deposition. J-V characteristics of this structure showed V{sub oc} = 435 mV and J{sub sc} = 0.08 mA/cm{sup 2} under illumination using a tungsten halogen lamp. Preparation of a photovoltaic structure using AgSbSe{sub 2} as an absorber material by a non-toxic selenization process is achieved.

  19. An investigation on silar Cu(In1-xAlx)Se2 thin films

    International Nuclear Information System (INIS)

    Dhanam, M.; Kavitha, B.; Velumani, S.

    2010-01-01

    Cu(In 1-x Al x )Se 2 [CIAS] thin films were prepared for the first time by successive ionic layer adsorption and reaction [SILAR] method with two different dipping cycles. The thickness of the films was measured by gravimetric technique. The structural, morphological, compositional, optical transition and electrical investigation of SILAR CIAS thin films with respect to two different dipping cycles have been discussed in this paper.

  20. Electrical and optical properties of spray - deposited CdSe thin films

    International Nuclear Information System (INIS)

    Bedir, M.; Oeztas, M.; Bakkaloglu, O. F.

    2002-01-01

    The CdSe thin films were developed by using spray-deposition technique at different substrate temperatures of 380C, 400C and, 420C on the glass substrate. All spraying processes involved CdCI 2 (0.05 moles/liter) and SeO 2 (0.05 moles/liter ) and were carried out in atmospheric condition. The CdSe thin film samples were characterized using x-ray diffractometer and optical absorption measurements. The electrical properties of the thin film samples were investigated via Wander Pauw method. XRD patterns indicated that the CdSe thin film samples have a hexagonal structure. The direct band gap of the CdSe thin film samples were determined from optical absorption and spectral response measurements of 1.76 eV. The resistivity of the CdSe thin film samples were found to vary in the range from 5.8x10''5 to 7.32x10''5 Ωcm depending to the substrate temperature

  1. High quality atomically thin PtSe2 films grown by molecular beam epitaxy

    Science.gov (United States)

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

    2017-12-01

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

  2. Electrosynthesis and characterization of Fe doped CdSe thin films from ethylene glycol bath

    International Nuclear Information System (INIS)

    Pawar, S.M.; Moholkar, A.V.; Rajpure, K.Y.; Bhosale, C.H.

    2007-01-01

    The CdSe and Fe doped CdSe (Fe:CdSe) thin films have been electrodeposited potentiostatically onto the stainless steel and fluorine doped tin oxide (FTO) glass substrates, from ethylene glycol bath containing (CH 3 COO) 2 .Cd.2H 2 O, SeO 2 , and FeCl 3 at room temperature. The doping concentration of Fe is optimized by using (photo) electrochemical (PEC) characterization technique. The deposition mechanism and Fe incorporation are studied by cyclic voltammetry. The structural, surface morphological and optical properties of the deposited CdSe and Fe:CdSe thin films have been studied by X-ray diffraction, scanning electron microscopy (SEM) and optical absorption techniques respectively. The PEC study shows that Fe:CdSe thin films are more photosensitive than that of undoped CdSe thin films. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure. SEM studies reveal that the films with uniformly distributed grains over the entire surface of the substrate. The complete surface morphology has been changed after doping. Optical absorption study shows the presence of direct transition and a considerable decrease in bandgap, E g from 1.95 to 1.65 eV

  3. Optical and structural properties of natural MnSeO{sub 4} mineral thin film

    Energy Technology Data Exchange (ETDEWEB)

    Kariper, Ishak Afsin, E-mail: akariper@gmail.com [Erciyes University, Education Faculty, Kayseri (Turkey)

    2017-05-15

    Manganese selenite (MnSeO{sub 4}) crystalline thin film has been produced with chemical bath deposition on substrates (commercial glass). Properties of the thin film, such as transmittance, absorption, and optical band gap and refraction index have been investigated via UV/VIS Spectrum. The structural properties of orthorhombic form have been observed in XRD. The structural and optical properties of MnSeO{sub 4} thin films, deposited at different pH levels were analyzed. Some properties of the films have been changed with the change of pH level, which has been deeply investigated. The grain size of MnSeO{sub 4} thin film has reached its highest value at pH 9. The refraction index and extinction coefficient of MnSeO{sub 4} thin films were measured to be 1.53, 2.86, 2.07, 1.53 (refraction index) and 0.005, 0.029, 0.014, 0.005 (extinction coefficient) for grain sizes 21, 13, 26, and 5 nm respectively. The band gaps (Eg) of the films were measured to be 2.06, 2.57, 2.04, and 2.76 eV for the grain sizes mentioned above. The value of dielectric constant at pH 10 was calculated as 1.575. (author)

  4. Growth and characterization of chalcostibite CuSbSe2 thin films for photovoltaic application

    Science.gov (United States)

    Tiwari, Kunal J.; Vinod, Vijay; Subrahmanyam, A.; Malar, P.

    2017-10-01

    Bulk copper antimony selenide was synthesized using mechanical alloying from the elemental precursors. Phase formation in milled powders was studied using x-ray diffraction (XRD) and Raman spectroscopy studies. The synthesized bulk source after cold compaction was used as source material for thin film deposition by e-beam evaporation. Thin film deposition was carried out at various e-beam current values (Ib ∼30, 40 and 50 mA) and at a substrate temperature of 200 °C. Near stoichiometric CuSbSe2 thin films were obtained for Ib values closer to 50 mA and post annealing at a temperature of 380 °C for 1 h. Thin films deposited using above conditions were found to exhibit an absorption coefficient (α) values of >105 cm-1 and a band gap value ∼1.18 eV that is closer to the reported band gap for CuSbSe2 compound.

  5. Auger-electron spectroscopy investigation of thin Ag-As-S-Se films

    International Nuclear Information System (INIS)

    Todorov, R; Spasov, G; Petkov, K; Tasseva, J

    2010-01-01

    The photoinduced changes in the refractive index and optical band-gap of thin As 32 S 34 Se 34 films photodoped with silver were studied using spectrophotometric methods. The compositional profile of the films was revealed by means of Auger-electron spectroscopy.

  6. Auger-electron spectroscopy investigation of thin Ag-As-S-Se films

    Energy Technology Data Exchange (ETDEWEB)

    Todorov, R; Spasov, G; Petkov, K; Tasseva, J, E-mail: jordanka@clf.bas.b [Acad. J. Malinowski Central Laboratory of Photoprocesses, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 109, 1113 Sofia (Bulgaria)

    2010-04-01

    The photoinduced changes in the refractive index and optical band-gap of thin As{sub 32}S{sub 34}Se{sub 34} films photodoped with silver were studied using spectrophotometric methods. The compositional profile of the films was revealed by means of Auger-electron spectroscopy.

  7. Deposition and characterization of CuInSe2 thin films

    International Nuclear Information System (INIS)

    Dhere, N.G.; Ferreira, C.L.; Cruz, L.R.O.; Mattoso, I.G.; Alves, R.M.P.

    1988-01-01

    CuInSe 2 thin films with 1,3 to 1,7 μm of thickness were deposited by the constituent elements (copper, indium and selenium) in glass substrate. The producted films were characterized by scanning microscopy, X-ray diffraction, Auger electron spectroscopy, Hall effect measures and optical absorption. (C.G.C.) [pt

  8. Structural and optical properties of Sb65Se35-xGex thin films

    Science.gov (United States)

    Saleh, S. A.; Al-Hajry, A.; Ali, H. M.

    2011-07-01

    Sb65Se35-xGex (x=0-20 at.%) thin films, prepared by the electron beam evaporation technique on ultrasonically cleaned glass substrates at 300 K, were investigated. The amorphous structure of the thin films was confirmed by x-ray diffraction analysis. The structure was deduced from the Raman spectra measured for all germanium contents in the Sb-Se-Ge matrix. The absorption coefficient (α) of the films was determined by optical transmission measurements. The compositional dependence of the optical band gap is discussed in light of topological and chemical ordered network models.

  9. Cathodic electrodeposition of CuInSe sub 2 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, C; Galiano, E; Herrero, J [Inst. de Energias Renovables (CIEMAT), Madrid (Spain)

    1991-01-01

    In order to study the preparation process of CuInSe{sub 2} thin films by a one-step electrodeposition method, thin films of the compound were prepared from aqueous citric acid (C{sub 6}H{sub 8}O{sub 7} . H{sub 2}O) plating baths onto titanium substrates. During electrodeposition, the bath composition and deposition potential were changed to obtain stoichiometric thin films. In general, close to stoichiometry, layers rich in selenium were observed, and this excess of selenium was removed after heat treatment. Best quality films were obtained after annealing at 400deg C during 15 min. X-ray diffraction showed the formation of CuInSe{sub 2} films, the chalcopyrite structure, at heating treatment temperatures higher than 350deg C. Optical measurements showed that the band gap of the deposited material was 0.99 eV. (orig.).

  10. Optical properties of Cd Se thin films obtained by pyrolytic dew

    International Nuclear Information System (INIS)

    Perez G, A.M.; Tepantlan, C.S.; Renero C, F.

    2006-01-01

    In this paper the optical properties of Cd Se thin films obtained by spray pyrolysis are presented. The films are prepared by Sodium Seleno sulphate (Na 2 SSeO 3 ) and Cadmium Chloride (CdC 12 ) mixing in aqueous environment. Optical parameters of the films (refractive index, absorption coefficient and optical ban gap) were calculated from transmittance spectra. The obtained values of the optical ban gap are compared with the result obtained by other deposition method. (Author)

  11. Composition and performance of thin film CdSe electrodeposited from selenosulfite solution

    International Nuclear Information System (INIS)

    Szabo, J.P.; Simms, D.; Cocivera, M.

    1985-01-01

    Cathodic electrodeposition of thin film CdSe from aqueous selenosulfite solution has been studied as function of solution composition and electrode potential. The Cd/Se ratio has been analyzed using polarography and Rutherford backscattering spectroscopy. Polarography gives a compostion averaged over the whole film (2cm 2 ) while RBS gives local surface composition (1 mm 2 ). The average Cd/Se ratio is 1.1, but some variation was found to occur across the surface of film (0.82 to 1.2)

  12. Composition-dependent nanostructure of Cu(In,Ga)Se{sub 2} powders and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Schnohr, C.S., E-mail: c.schnohr@uni-jena.de [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Kämmer, H.; Steinbach, T.; Gnauck, M. [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Rissom, T.; Kaufmann, C.A.; Stephan, C. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Schorr, S. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstr. 74-100, 12249 Berlin (Germany)

    2015-05-01

    Atomic-scale structural parameters of Cu(In,Ga)Se{sub 2} powders and polycrystalline thin films were determined as a function of the In and Cu contents using X-ray absorption spectroscopy. No difference in the two sample types is observed for the average bond lengths demonstrating the strong tendency towards bond length conservation typical for tetrahedrally coordinated semiconductors. In contrast, the bond length variation is significantly smaller in the thin films than in the powders, particularly for Cu-poor material. This difference in the nanostructure is proposed to originate from differences in the preparation conditions, most prominently from the different history of Cu composition. - Highlights: • Cu(In,Ga)Se{sub 2} powders and thin films are studied with X-ray absorption spectroscopy. • Structural parameters are determined as a function of the In and Cu contents. • The element-specific average bond lengths are identical for powders and thin films. • The Ga-Se/In-Se bond length variation is smaller for thin films than for powders. • The differences are believed to stem from the different history of the Cu content.

  13. Optical properties of n-CdSe sub 1-x Te sub x polycrystalline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, M T [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain). Inst. de Energias Renovables

    1991-01-01

    Absorption coefficient, {alpha}({lambda}), and energy gap, E{sub g}, of CdSe{sub 1-x}Te{sub x} thin films were determined from the measured transmittance and reflectance at normal incidence of light in the wavelength range 450-2500 nm. The thin film were electrochemically prepared on glass plates coated with conducting thin films of SnO{sub 2}. A combined method from Goodman and Lubberts was used to determine the absorption coefficient and its dependence on the wavelength. The evolution of the optical gap versus the composition of Te in CdSe{sub 1-x}Te{sub x} was made and a value of 1.4 eV of the optical gap was obtained for the composition of CdSe{sub 0.65}Te{sub 0.35}. (orig.).

  14. Synthesis, structure and magnetic properties of crystallographically aligned CuCr_2Se_4 thin films

    International Nuclear Information System (INIS)

    Esters, Marco; Liebig, Andreas; Ditto, Jeffrey J.; Falmbigl, Matthias; Albrecht, Manfred; Johnson, David C.

    2016-01-01

    We report the low temperature synthesis of highly textured CuCr_2Se_4 thin films using the modulated elemental reactant (MER) method. The structure of CuCr_2Se_4 is determined for the first time in its thin film form and exhibits cell parameters that are smaller than found in bulk CuCr_2Se_4. X-ray diffraction and precession electron diffraction show a strong degree of crystallographic alignment of the crystallites, where the axis is oriented perpendicular to the substrate surface, while being rotationally disordered within the plane. Temperature and field dependent in-plane and out-of-plane magnetization measurements show that the film is ferromagnetic with a Curie temperature of 406 K CuCr_2Se_4 synthesized utilizing the MER method shows stronger magnetic anisotropy (effective anisotropy: 1.82 × 10"6 erg cm"−"3; shape anisotropy: 1.07 × 10"6 erg cm"−"3), with the easy axis lying out of plane, and a larger magnetic moment (6 μ_B/f.u.) than bulk CuCr_2Se_4. - Highlights: • Crystallographically aligned, phase pure CuCr_2Se_4 were synthesized. • The degree of alignment decreases with annealing time. • The films are ferromagnetic with the easy axis along the direction. • The magnetization is larger than bulk CuCr_2Se_4 or other CuCr_2Se_4 films made to date.

  15. Phonon and thermal properties of exfoliated TaSe{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Z.; Jiang, C.; Renteria, J. [Nano-Device Laboratory, Department of Electrical Engineering, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Pope, T. R.; Tsang, C. F.; Stickney, J. L.; Salguero, T. T., E-mail: salguero@uga.edu, E-mail: balandin@ee.ucr.edu [Department of Chemistry, University of Georgia, Athens, Georgia 30602 (United States); Goli, P. [Materials Science and Engineering Program, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Balandin, A. A., E-mail: salguero@uga.edu, E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory, Department of Electrical Engineering, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Materials Science and Engineering Program, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States)

    2013-11-28

    We report on the phonon and thermal properties of thin films of tantalum diselenide (2H-TaSe{sub 2}) obtained via the “graphene-like” mechanical exfoliation of crystals grown by chemical vapor transport. The ratio of the intensities of the Raman peak from the Si substrate and the E{sub 2g} peak of TaSe{sub 2} presents a convenient metric for quantifying film thickness. The temperature coefficients for two main Raman peaks, A{sub 1g} and E{sub 2g}, are −0.013 and −0.0097 cm{sup −1}/{sup o}C, respectively. The Raman optothermal measurements indicate that the room temperature thermal conductivity in these films decreases from its bulk value of ∼16 W/mK to ∼9 W/mK in 45-nm thick films. The measurement of electrical resistivity of the field-effect devices with TaSe{sub 2} channels shows that heat conduction is dominated by acoustic phonons in these van der Waals films. The scaling of thermal conductivity with the film thickness suggests that the phonon scattering from the film boundaries is substantial despite the sharp interfaces of the mechanically cleaved samples. These results are important for understanding the thermal properties of thin films exfoliated from TaSe{sub 2} and other metal dichalcogenides, as well as for evaluating self-heating effects in devices made from such materials.

  16. Phonon and thermal properties of exfoliated TaSe2 thin films

    International Nuclear Information System (INIS)

    Yan, Z.; Jiang, C.; Renteria, J.; Pope, T. R.; Tsang, C. F.; Stickney, J. L.; Salguero, T. T.; Goli, P.; Balandin, A. A.

    2013-01-01

    We report on the phonon and thermal properties of thin films of tantalum diselenide (2H-TaSe 2 ) obtained via the “graphene-like” mechanical exfoliation of crystals grown by chemical vapor transport. The ratio of the intensities of the Raman peak from the Si substrate and the E 2g peak of TaSe 2 presents a convenient metric for quantifying film thickness. The temperature coefficients for two main Raman peaks, A 1g and E 2g , are −0.013 and −0.0097 cm −1 / o C, respectively. The Raman optothermal measurements indicate that the room temperature thermal conductivity in these films decreases from its bulk value of ∼16 W/mK to ∼9 W/mK in 45-nm thick films. The measurement of electrical resistivity of the field-effect devices with TaSe 2 channels shows that heat conduction is dominated by acoustic phonons in these van der Waals films. The scaling of thermal conductivity with the film thickness suggests that the phonon scattering from the film boundaries is substantial despite the sharp interfaces of the mechanically cleaved samples. These results are important for understanding the thermal properties of thin films exfoliated from TaSe 2 and other metal dichalcogenides, as well as for evaluating self-heating effects in devices made from such materials

  17. Phonon and thermal properties of exfoliated TaSe2 thin films

    Science.gov (United States)

    Yan, Z.; Jiang, C.; Pope, T. R.; Tsang, C. F.; Stickney, J. L.; Goli, P.; Renteria, J.; Salguero, T. T.; Balandin, A. A.

    2013-11-01

    We report on the phonon and thermal properties of thin films of tantalum diselenide (2H-TaSe2) obtained via the "graphene-like" mechanical exfoliation of crystals grown by chemical vapor transport. The ratio of the intensities of the Raman peak from the Si substrate and the E2g peak of TaSe2 presents a convenient metric for quantifying film thickness. The temperature coefficients for two main Raman peaks, A1g and E2g, are -0.013 and -0.0097 cm-1/oC, respectively. The Raman optothermal measurements indicate that the room temperature thermal conductivity in these films decreases from its bulk value of ˜16 W/mK to ˜9 W/mK in 45-nm thick films. The measurement of electrical resistivity of the field-effect devices with TaSe2 channels shows that heat conduction is dominated by acoustic phonons in these van der Waals films. The scaling of thermal conductivity with the film thickness suggests that the phonon scattering from the film boundaries is substantial despite the sharp interfaces of the mechanically cleaved samples. These results are important for understanding the thermal properties of thin films exfoliated from TaSe2 and other metal dichalcogenides, as well as for evaluating self-heating effects in devices made from such materials.

  18. Thermal characterization of Se-Te thin films

    Czech Academy of Sciences Publication Activity Database

    Svoboda, R.; Kincl, Miloslav; Málek, J.

    2015-01-01

    Roč. 644, 25 September (2015), s. 40-46 ISSN 0925-8388 Institutional support: RVO:61389013 Keywords : krystallization kinetics * DSC * Se-Te glass Subject RIV: CA - Inorganic Chemistry Impact factor: 3.014, year: 2015

  19. Giant spin Hall angle from topological insulator BixSe(1 - x) thin films

    Science.gov (United States)

    Dc, Mahendra; Jamali, Mahdi; Chen, Junyang; Hickey, Danielle; Zhang, Delin; Zhao, Zhengyang; Li, Hongshi; Quarterman, Patrick; Lv, Yang; Mkhyon, Andre; Wang, Jian-Ping

    Investigation on the spin-orbit torque (SOT) from large spin-orbit coupling materials has been attracting interest because of its low power switching of the magnetization and ultra-fast driving of the domain wall motion that can be used in future spin based memory and logic devices. We investigated SOT from topological insulator BixSe(1 - x) thin film in BixSe(1 - x) /CoFeB heterostructure by using the dc planar Hall method, where BixSe(1 - x) thin films were prepared by a unique industry-compatible deposition process. The angle dependent Hall resistance was measured in the presence of a rotating external in-plane magnetic field at bipolar currents. The spin Hall angle (SHA) from this BixSe(1 - x) thin film was found to be as large as 22.41, which is the largest ever reported at room temperature (RT). The giant SHA and large spin Hall conductivity (SHC) make this BixSe(1 - x) thin film a very strong candidate as an SOT generator in SOT based memory and logic devices.

  20. Chemical bath deposition of Hg doped CdSe thin films and their characterization

    International Nuclear Information System (INIS)

    Bhuse, V.M.

    2005-01-01

    The deliberate addition of Hg in CdSe thin film have been carried out using a simple, modified, chemical bath deposition technique with the objective to study the effect of Hg doping on properties of CdSe thin films. Synthesis was initiated at 278 K temperature using complexed cadmium sulphate, mercuric nitrate and sodium selenosulphate in an aqueous ammonical medium at pH 10. Films were characterized by XRD, SEM, optical absorption, electrical and thermoelectric techniques. The 'as deposited' films were uniform, well adherent, nearly stoichiometric and polycrystalline in a single cubic phase (zinc blende). Crystallite size determined from XRD and SEM was found to increase slightly with addition of Hg. The optical band gap of CdSe remains constant upto 0.05 mol% Hg doping, while it decreases monotonically with further increase in mercury content. Dark dc electrical resistivity and conduction activation energy of CdSe were found to decrease initially upto 0.05 mol% of Hg, thereafter increased for higher values of Hg but remains less than those of CdSe. All the films showed n-type of conductivity. A CdSe film containing 0.05 mol% of Hg showed higher absorption coefficient, and conductivity

  1. Dual-bath electrodeposition of n-type Bi–Te/Bi–Se multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, Ken; Okuhata, Mitsuaki; Takashiri, Masayuki, E-mail: takashiri@tokai-u.jp

    2015-11-15

    N-type Bi–Te/Bi–Se multilayer thin films were prepared by dual-bath electrodeposition. We varied the number of layers from 2 to 10 while the total film thickness was maintained at approximately 1 μm. All the multilayer films displayed the X-ray diffraction peaks normally observed from individual Bi{sub 2}Te{sub 3} and Bi{sub 2}Se{sub 3} crystal structures, indicating that both phases coexist in the multilayer. The cross-section of the 10-layer Bi–Te/Bi–Se film was composed of stacked layers with nano-sized grains but the boundaries between the layers were not planar. The Seebeck coefficient was almost constant throughout the entire range of our experiment, but the electrical conductivity of the multilayer thin films increased significantly as the number of layers was increased. This may be because the electron mobility increases as the thickness of each layer is decreased. As a result of the increased electrical conductivity, the power factor also increased with the number of layers. The maximum power factor was 1.44 μW/(cm K{sup 2}) for the 10-layer Bi–Te/Bi–Se film, this was approximately 3 times higher than that of the 2-layer sample. - Highlights: • N-type Bi–Te/Bi–Se multilayer thin films were deposited by electrodeposition. • We employed a dual-bath electrodeposition process for preparing the multilayers. • The Bi–Te/Bi–Se film was composed of stacked layers with nano-sized grains. • The electrical conductivity increased as the number of layers was increased. • The power factor improved by 3 times as the number of layers was increased.

  2. On Some Physical Properties of GeSe3-Sb2Se3-ZnSe Thin Films and Their Radiation Response

    International Nuclear Information System (INIS)

    Hosni, H.M.M.A.

    2010-01-01

    Thin films of the chalcogenides GeSe 3 , Sb 2 Se 3 , ZnSe, (GeSe 3 )80(Sb 2 Se 3 )20 and (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20, are prepared by thermal evaporation onto glass substrates. The effect of ZnSe incorporation with both GeSe 3 , Sb 2 Se 3 results in amorphous (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 composition as obtained from the X-ray analysis. Electrical measurements reveal a decrease in dc activation energy, ΔEdc, and an increase in ac activation energy, ΔEac, for (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 as compared with (GeSe 3 )80(Sb 2 Se 3 )20. Optical energy gap, Eg, and band tail width, Ee, are estimated in UV/VIS spectral region for fresh and γ-irradiated films, revealing a decrease in Eg and an increase in Ee for ZnSe and (GeSe 3 )70(Sb 2 Se 3 )10(ZnSe)20 compositions, with irradiation dose.

  3. Structural, morphological and optical properties of pulsed laser deposited ZnSe/ZnSeO3 thin films

    Science.gov (United States)

    Hassan, Syed Ali; Bashir, Shazia; Zehra, Khushboo; Salman Ahmed, Qazi

    2018-04-01

    The effect of varying laser pulses on structural, morphological and optical behavior of Pulsed Laser Deposited (PLD) ZnSe/ZnSeO3 thin films has been investigated. The films were grown by employing Excimer laser (100 mJ, 248 nm, 18 ns, 30 Hz) at various number of laser pulses i.e. 3000, 4000, 5000 and 6000 with elevated substrate temperature of 300 °C. One film was grown at Room Temperature (RT) by employing 3000 number of laser pulses. In order to investigate the structural analysis of deposited films, XRD analysis was performed. It was observed that the room temperature is not favorable for the growth of crystalline film. However, elevated substrate temperature to 300°C, two phases with preferred orientation of ZnSeO3 (2 1 2) and ZnSe (3 3 1) were identified. AFM and SEM analysis were performed to explore the surface morphology of grown films. Morphological analysis also confirmed the non-uniform film growth at room temperature. At elevated substrate temperature (300 °C), the growth of dendritic rods and cubical crystalline structures are observed for lower number of laser pulses i.e. 3000 and 4000 respectively. With increased number of pulses i.e. 5000 and 6000, the films surface morphology becomes smooth which is confirmed by measurement of surface RMS roughness. Number of grains, skewness, kurtosis and other parameters have been evaluated by statistical analysis. In order to investigate the thickness, and optical properties of deposited films, ellipsometery and UV–Vis spectroscopy techniques were employed. The estimated band gap energy is 2.67 eV for the film grown at RT, whereas band gap values varies from 2.80 eV to 3.01 eV for the films grown at 300 °C with increasing number of laser pulses.

  4. Progress in Polycrystalline Thin-Film Cu(In,GaSe2 Solar Cells

    Directory of Open Access Journals (Sweden)

    Udai P. Singh

    2010-01-01

    Full Text Available For some time, the chalcopyrite semiconductor CuInSe2 and its alloy with Ga and/or S [Cu(InGaSe2 or Cu(InGa(Se,S2], commonly referred as CIGS, have been leading thin-film material candidates for incorporation in high-efficiency photovoltaic devices. CuInSe2-based solar cells have shown long-term stability and the highest conversion efficiencies among all thin-film solar cells, reaching 20%. A variety of methods have been reported to prepare CIGS thin film. Efficiency of solar cells depends upon the various deposition methods as they control optoelectronic properties of the layers and interfaces. CIGS thin film grown on glass or flexible (metal foil, polyimide substrates require p-type absorber layers of optimum optoelectronic properties and n-type wideband gap partner layers to form the p-n junction. Transparent conducting oxide and specific metal layers are used for front and back contacts. Progress made in the field of CIGS solar cell in recent years has been reviewed.

  5. Characteristics of CuInSe sub 2 thin films grown by the selenization method

    CERN Document Server

    Kim, S D; Adurodija, F O; Yoon, K H; Song, J S

    1999-01-01

    CuInSe sub 2 thin films were formed from a selenization of co-sputtered Cu-In alloy layers which consisted of only two phases, CuIn sub 2 and Cu sub 1 sub 1 In sub 9. A linear dependence of the Cu-In alloy film composition on the Cu/In sputtering power was found. The metallic layers were selenized in vacuum or at 1 atm. A small number of Cu-Se and In-Se compounds was observed during the early stage of selenization, and single-phase CuInSe sub 2 was more easily formed in vacuum than at atmospheric pressure. Therefore, CuInSe sub 2 films selenized in vacuum showed larger grain sizes, smoother surfaces, and denser microstructures than those selenized at 1 atm.

  6. Characteristics of CuInSe2 thin films grown by the selenization method

    International Nuclear Information System (INIS)

    Kim, Sang Deok; Kim, Hyeong Joon; Adurodija, Frederick Ojo; Yoon, Kyeong Hoon; Song, Jin Soo

    1999-01-01

    CuInSe 2 thin films were formed from a selenization of co-sputtered Cu-In alloy layers which consisted of only two phases, CuIn 2 and Cu 11 In 9 . A linear dependence of the Cu-In alloy film composition on the Cu/In sputtering power was found. The metallic layers were selenized in vacuum or at 1 atm. A small number of Cu-Se and In-Se compounds was observed during the early stage of selenization, and single-phase CuInSe 2 was more easily formed in vacuum than at atmospheric pressure. Therefore, CuInSe 2 films selenized in vacuum showed larger grain sizes, smoother surfaces, and denser microstructures than those selenized at 1 atm

  7. Electrochemical synthesis of photoactive In/sub 2/Se/sub 3/ thin films

    Energy Technology Data Exchange (ETDEWEB)

    Herrero, J; Ortega, J

    1987-12-01

    In/sub 2/Se/sub 3/ thin films were grown by alternate electrodeposition of selenium and indium from separate baths onto titanium substrates with subsequent thermal annealing. The influence of annealing temperature on the properties of the obtained films was examined. The results of X-ray diffraction patterns led to the conclusion that films were ..beta..-phase when the temperature ranged between 300 and 500/sup 0/C. At 600/sup 0/C the thin film loses Se and the ratio Se/In decreases. Only photoanodic response, n-type thin films, was observed when the samples were tested in a photoelectrochemical cell with a sulfite/sulfate redox couple. Values of the photocurrent on the spectra response were increased when the annealing temperature was also increased, showing the best photocurrent values at 500/sup 0/C, and the films that were annealed at 600/sup 0/C showed no photoactivity. Spectral responses after chemical etching of the samples showed a significant increase of the photocurrent. Application of Gaertner-Butler's model to the interface semiconductor-electrolyte makes it possible to obtain the semiconductor energy gap, on samples heated at 500/sup 0/C, corresponding to a direct allowed band transition.

  8. Preparation of CulnSe2 thin films by paste coating

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Precursor pastes were obtained by milling Cu-In alloys and Se powders.CuInSe2 thin films were successfully prepared by precursor layers,which were coated using these pastes,and were annealed in a H2 atmosphere.The pastes were tested by laser particle diameter analyzer,simultaneous thermogravimetric and differential thermal analysis instruments (TG-DTA),and X-ray diffractometry (XRD).Selenized films were characterized by XRD,scanning electron microscopy (SEM),and energy dispersive spectroscopy (EDS).The results indicate that chalcopyrite CuInSe2 is formed at 180℃ and the crystallinity of this phase is improved as the temperature rises.All the CuInSe2 thin films,which were annealed at various temperatures,exhibit the preferred orientation along the (112) plane.The compression of precursor layers before selenization step is one oftbe most essential factors for the preparation of perfect CulnSe2 thin films.

  9. Facile synthesis and photo electrochemical performance of SnSe thin films

    Science.gov (United States)

    Pusawale, S. N.; Jadhav, P. S.; Lokhande, C. D.

    2018-05-01

    Orthorhombic structured SnSe thin films are synthesized via SILAR (successive ionic layer adsorption and reaction) method on glass substrates. The structural properties of thin films are characterized by x-ray diffraction, scanning electron microscopy studies from which nanoparticles with an elongated shape and hydrophilic behavior are observed. UV -VIS absorption spectroscopy study showed the maximum absorption in the visible region with a direct band gap of 1.55 eV. The photo electrochemical study showed p-type electrical conductivity.

  10. One, step electrodeposition of Cu(Ga,In)Se2 thin films from aqueous solution

    Science.gov (United States)

    Fahoume, M.; Boudraine, H.; Aggour, M.; Chraïbi, F.; Ennaoui, A.; Delplancke, J. L.

    2005-03-01

    Cu(In,Ga)Se{2} (CIGS) semiconducting thin films films were prepared by electrodeposition from aqueous solution containing CuCl{2}, InCl{3}, GaCl{3} and H{2}SeO{3}. The deposited material was characterized by cyclic voltammetry. The compositional, structural studies were carried out using scanning electron microscopy (SEM), energy dispersive X-ray microanalysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). X-ray analysis showed the formation of CuIn{1-x}GaxSe{2} films, in the optimum conditions, with preferred orientation in the (112) direction. We observed a shift of the peaks to higher angles with increasing x, accounting for a decrease of the lattice constants when In atoms are substituted by Ga atoms. Element mapping and scanline (EDX) indicate that the Cu, In, Ga, and Se elements are homogeneously distributed.

  11. Linear and nonlinear optical properties of Sb-doped GeSe2 thin films

    Science.gov (United States)

    Zhang, Zhen-Ying; Chen, Fen; Lu, Shun-Bin; Wang, Yong-Hui; Shen, Xiang; Dai, Shi-Xun; Nie, Qiu-Hua

    2015-06-01

    Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb-Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10-18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10-10 m/W. These excellent properties indicate that Sb-doped Ge-Se films have a good prospect in the applications of nonlinear optical devices. Project supported by the National Key Basic Research Program of China (Grant No. 2012CB722703), the National Natural Science Foundation of China (Grant No. 61377061), the Young Leaders of Academic Climbing Project of the Education Department of Zhejiang Province, China (Grant No. pd2013092), the Program for Innovative Research Team of Ningbo City, China (Grant No. 2009B217), and the K. C. Wong Magna Fund in Ningbo University, China.

  12. Electrodeposition of near stoichiometric CuInSe2 thin films for photovoltaic applications

    Science.gov (United States)

    Chandran, Ramkumar; Mallik, Archana

    2018-03-01

    This work investigates on the single step electrodeposition of quality CuInSe2 (CIS) thin film absorber layer for photovoltaics applications. The electrodeposition was carried using an aqueous acidic solution with a pH of 2.25. The deposition was carried using a three electrode system in potentiostatic conditions for 50 minutes. The as-deposited and nitrogen (N2) annealed films were characterized using XRD, FE-SEM and Raman spectroscopy. It has been observed that the SDS has the tendency to suppress the copper selenide (CuxSe) secondary phase which is detrimental to the device performance.

  13. Colloidal CuInSe2 nanocrystals thin films of low surface roughness

    International Nuclear Information System (INIS)

    Kergommeaux, Antoine de; Fiore, Angela; Faure-Vincent, Jérôme; Pron, Adam; Reiss, Peter

    2013-01-01

    Thin-film processing of colloidal semiconductor nanocrystals (NCs) is a prerequisite for their use in (opto-)electronic devices. The commonly used spin-coating is highly materials consuming as the overwhelming amount of deposited matter is ejected from the substrate during the spinning process. Also, the well-known dip-coating and drop-casting procedures present disadvantages in terms of the surface roughness and control of the film thickness. We show that the doctor blade technique is an efficient method for preparing nanocrystal films of controlled thickness and low surface roughness. In particular, by optimizing the deposition conditions, smooth and pinhole-free films of 11 nm CuInSe 2 NCs have been obtained exhibiting a surface roughness of 13 nm root mean square (rms) for a 350 nm thick film, and less than 4 nm rms for a 75 nm thick film. (paper)

  14. Defects in CdSe thin films, induced by high energy electron irradiation

    International Nuclear Information System (INIS)

    Ion, L.; Antohe, S.; Tutuc, D.; Antohe, V.A.; Tazlaoanu, C.

    2004-01-01

    Defects induced in CdSe thin films by high energy electron irradiation are investigated by means of thermally stimulated currents (TSC) spectroscopy. Films were obtained by vacuum deposition from a single source and irradiated with a 5 x 10 13 electrons/cm 2 s -1 beam of 6-MeV energy. It was found that electrical properties of the films are controlled by a deep donor state, located at 0.38 eV below the bottom edge of the conduction band. Parameters of the traps responsible for the recorded TSC peaks were determined. (authors)

  15. Effect of Se addition on optical and electrical properties of chalcogenide CdSSe thin films

    Science.gov (United States)

    Hassanien, A. S.; Akl, Alaa A.

    2016-01-01

    Compositional dependence of optical and electrical properties of chalcogenide CdSxSe1-x (0.4 ≥ x ≥ 0.0 at. %) thin films was studied. Cadmium sulphoselenide films were deposited by thermal evaporation technique at vacuum (8.2 × 10-4 Pa) onto preheated glass substrates (523 K). The evaporation rate and film thickness were kept constant at 2.50 nm/s and 375 ± 5 nm, respectively. X-ray diffractograms showed that, the deposited films have the low crystalline nature. Energy dispersive analysis by X-ray (EDAX) was used to check the compositional elements of deposited films. The absorption coefficient was determined from transmission and reflection measurements at room temperature in the wavelength range 300-2500 nm. Optical density, skin depth, optical energy gap and Urbach's parameters of CdSSe thin films have also been estimated. The direct optical energy gap decreased from 2.248 eV to 1.749 eV when the ratio of Se-content was increased from 0.60 to 1.00 . Conduction band and valance band positions were evaluated. The temperature dependence of dc-electrical resistivity in the temperature range (293-450 K) has been reported. Three conduction regions due to different conduction mechanisms were detected. Electrical sheet resistance, activation energy and pre-exponential parameters were discussed. The estimated values of optical and electrical parameters were strongly dependent upon the Se-content in CdSSe matrix.

  16. Electrochemical preparation and characterization of CuInSe2 thin films for photovoltaic applications

    International Nuclear Information System (INIS)

    Guillen Arqueros, C.

    1992-01-01

    The objective of this work has been to investigate the electrodeposition as a low-cost, large-area fabrication process to obtain CuInSe 2 this films for efficient photovoltaic devices. this objective entails the elucidation of thin film deposition mechanism, the study of the fundamental properties of electrodeposited material, and also the modification of their physical and chemical parameters for photovoltaic applications. CuInSe 2 thin films have been successfully electrodeposited from a citric was characterized by compositional, structural, electrical, optical and electrochemical measurements, relating their properties with the preparation parameters and also studying the effect of various thermal and chemical treatments. The results showed post-deposition treatment are needed for optimizing these films for solar cells fabrication: first, an annealing in inert atmosphere at temperatures above 400 degrees celsius to obtain a high recrystallization in the chalcopyrite structure, and after a chemical etching in KCN solution to remove secondary phases of Cu x Se and Se which are frequently electrodeposited with the CuInSe 2 . The treated samples showed appropriate photovoltaic activity in a semiconductor-electrolite liquid junction. (author) 193 ref

  17. Electrodeposition and characterization of CdSe x-Te 1- x semiconducting thin films

    Science.gov (United States)

    Benamar, E.; Rami, M.; Fahoume, M.; Chraibi, F.; Ennaoui, A.

    1999-07-01

    Thin polycrystalline films of cadmium chalcogenides CdSe xTe 1-x ( 0 ≤ x ≤ 1) have been prepared by electrochemical plating on ITO (indium tin oxide) coated glass substrates from an acid sulfate solution at 90 °C. Structural, morphological and compositional studies of the deposited films are reported as a function of the x coefficient. XRD analysis shows that all deposits have a cubic structure with a preferred orientation along the (111) direction. The composition in the films is found to vary linearly with the composition in the solution. The increase in the selenium content x in the CdSe xTe 1-x films decreases the lattice constant and increases the band gap. Nevertheless this latter presents a minimum for x = 0.27.

  18. Density functional study of BiSbTeSe{sub 2} topological insulator thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadpourrad, Zahra; Abolhassani, Mohammadreza [Department of Physics, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2017-08-15

    In this work, using density functional theory calculations, we have investigated the band topology of bulk BiSbTeSe{sub 2} and its thin film electronic properties in several thicknesses. It is one member of the quaternary compounds Bi{sub 2-x}Sb{sub x}Te{sub 3-y}Se{sub y} (BSTS) with the best intrinsic bulk insulating behavior. Based on our calculations we have found that a band inversion at Γ-point is induced when spin-orbit coupling is turned on, with an energy gap of about 0.318 eV. The film thickness has an effect on the surface states such that a gap opens at Dirac point in 6 quintuple-layers film and with decrease in thickness, the magnitude of the gap increases. The atomic contributions have been mapped out for the first few layers of thin films to demonstrate the surface states. The relative charge density has been calculated layer-wise and the penetration depth of the surface states into the bulk region is found to be about 2.5-3.5 quintuple layers, depending on the termination species of thin films. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Room temperature deposition of ZnSe thin films by successive ionic layer adsorption and reaction (SILAR) method

    International Nuclear Information System (INIS)

    Kale, R.B.; Lokhande, C.D.

    2004-01-01

    The zinc selenide (ZnSe) thin films are deposited onto glass substrate using relatively simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. The films are deposited using zinc acetate sodium selenosulphate precursors. The concentration, pH, immersion and rinsing times and number of immersion cycles have been optimized to obtain good quality ZnSe thin films. The X-ray diffraction (XRD) study and scanning electron microscopy (SEM) studies reveals nanocrystalline nature alongwith some amorphous phase present in ZnSe thin films. Energy dispersive X-ray (EDAX) analysis shows that the films are Se deficient. From optical absorption data, the optical band gap 'E g ' for as-deposited thin film was found to be 2.8 eV and electrical resistivity in the order of 10 7 Ω cm

  20. Rate constant of free electrons and holes recombination in thin films CdSe

    International Nuclear Information System (INIS)

    Radychev, N.A.; Novikov, G.F.

    2006-01-01

    Destruction kinetics of electrons generated in thin films CdSe by laser impulse (wave length is 337 nm, period of impulse - 8 nc) is studied by the method of microwave photoconductivity (36 GHz) at 295 K. Model of the process was suggested using the analysis of kinetics of photo-responses decay, and it allowed determination of rate constant of recombination of free electrons and holes in cadmium selenide - (4-6)x10 -11 cm 3 s -1 [ru

  1. Structural, optical and electrical characterization of Ag doped lead chalcogenide (PbSe) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ghamdi, A.A., E-mail: aghamdi90@hotmail.com [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Al-Heniti, S. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia); Khan, Shamshad A. [Department of Physics, St. Andrew' s College, Gorakhpur, UP (India)

    2013-03-15

    Research and development efforts are currently underway to fabricate a variety of solid state devices. A good deal of information regarding the synthesis, structural, optical and electrical properties of Ag doped lead chalcogenides have been revealed. The bulk polycrystalline (PbSe){sub 100-x}Ag{sub x} ternary chalcogenides are prepared by diffusion technique. The XRD patterns recorded for the (PbSe){sub 100-x}Ag{sub x} thin films prepared by vacuum deposition technique, show that these films are polycrystalline in nature. The optical measurements reveal that the (PbSe){sub 100-x}Ag{sub x} thin films possess direct band gap and the band gap energy decreases with an increase of Ag concentration. The extinction coefficient (k) and refractive index (n) are found to be changing by increasing Ag concentration in PbSe. These results are interpreted in terms of the change in concentration of localized states due to the shift in Fermi level. The dc conductivities of (PbSe){sub 100-x}Ag{sub x} thin films are measured in temperature range 303-403 K. It is observed that the dc conductivity increases at all the temperatures with an increase of Ag content in PbSe system. The experimental data suggests that the conduction is due to thermally assisted tunneling of the charge carriers in the localized states near the band edges. The activation energy and optical band gap are found to decrease with increasing Ag concentration in lead chalcogenide and there are good agreements between these two values. - Highlights: Black-Right-Pointing-Pointer (PbSe){sub 100-x}Ag{sub x} thin films has been investigated. Black-Right-Pointing-Pointer Polycrystalline nature has been verified by X-ray diffraction. Black-Right-Pointing-Pointer Optical absorption data showed the rules of direct transitions predominate. Black-Right-Pointing-Pointer Dc conductivity increases with an increase of Ag content in PbSe system. Black-Right-Pointing-Pointer Increase of Ag concentration causes a decrease in E{sub g

  2. Ion beam analysis of Cu(In,Ga)Se{sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Karydas, A.G. [International Atomic Energy Agency (IAEA), IAEA Laboratories, Nuclear Science and Instrumentation Laboratory, A-2444 Seibersdorf (Austria); Institute of Nuclear and Particle Physics, NCSR “Demokritos”, 153 10 Aghia Paraskevi, Athens Greece (Greece); Streeck, C. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany); Radovic, I. Bogdanovic [Ruđer Bošković Institute (RBI), Zagreb (Croatia); Kaufmann, C.; Rissom, T. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Beckhoff, B. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany); Jaksic, M. [Ruđer Bošković Institute (RBI), Zagreb (Croatia); Barradas, N.P. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, E. N. 10, Apartado 21, 2686-953 Sacavém (Portugal)

    2015-11-30

    Graphical abstract: - Highlights: • Elemental depth profiles for various CIGS thin films were quantitatively determined. • Pure absorbers, complete cell and bilayer solar cells were prepared and analyzed. • Synergistic PIXE and RBS analysis of thin solar cells using alpha beam particles. • High energy alpha beam resolved completely the Indium depth profile. • Synchrotron based Reference Free GIXRF quantitative analysis validated IBA results. - Abstract: The present work investigates the potential of ion beam analysis (IBA) techniques such as the Rutherford backscattering spectrometry (RBS) and particle induced X-ray emission (PIXE) using helium ions to provide quantitative in-depth elemental analysis of various types of Cu(In,Ga)Se{sub 2} thin films. These films with a thickness of about 2 μm are used as absorber layers in photovoltaic devices with continuously increasing the performance of this technology. The preparation process generally aims to obtain an in-depth gradient of In and Ga concentrations that optimizes the optoelectronic and electrical properties of the solar cell. The measurements were performed at directly accessible single or double layered CIGS absorbers and at buried absorbers in completed thin film solar cells. The IBA data were analyzed simultaneously in order to derive best fitted profiles that match all experimental RBS and PIXE spectra. For some samples elemental profiles deduced form synchrotron based, reference free grazing incidence X-ray fluorescence analysis were compared with the IBA results and an overall good agreement was observed within quoted uncertainties.

  3. Electrochemical growth and studies of CuInSe2 thin films

    International Nuclear Information System (INIS)

    Prasher, Dixit; Chandel, Tarun; Rajaram, Poolla

    2014-01-01

    Thin films of CuInSe 2 were grown on fluorine doped tin oxide (<10 Ω/□) coated glass using the electrodeposition technique. The electrodeposition was carried out potentiostatically using an aqueous bath consisting of solutions of CuCl 2 , InCl 3 and SeO 2 with ethylenediamine-dihydrochloride (EDC) added for complexation. CuInSe 2 films were also deposited without using any complexing agent in the bath. To improve the crystallinity the CuInSe 2 films were annealed in vaccum at 300 °C for one hour. The annealed films were analyzed by x-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive analysis of x-rays (EDAX), atomic force microscopy (AFM) and optical spectra. The results obtained in this work show that by adding a suitable complexing agent to the electrochemical bath, nanocrystalline CuInSe 2 , 20 nm to 30 nm in size, can be grown. The composition of the CuInSe 2 films can be controlled by means of the bath composition and stoichiometric films can be obtained for a bath with ionic Cu:In:Se composition close to 1:4:2. AFM micrographs show that the particles are generally oval shaped for near stoichiometric compositions. However for extreme copper rich layers, the morphology is completely different, the particles in this case appearing in the form of nanoflakes. Each flake has a thickness in the nano range, but the surface extends to a length of several microns. (papers)

  4. Fe-Vacancy-Induced Ferromagnetism in Tetragonal FeSe Thin Films

    International Nuclear Information System (INIS)

    Yong-Feng, Li; Gui-Bin, Liu; Li-Jie, Shi; Bang-Gui, Liu

    2009-01-01

    Motivated by recent experiments, we investigate structural, electronic, and magnetic properties of tetragonal FeSe with Fe vacancies using the state-of-the-art first-principles method. We show that Fe vacancies tend to stay in the same one of the two sublattices and thus induce ferromagnetism in the ground-state phase. Our calculated net moment is in good agreement with the experimental data available. Therefore, the ferromagnetism observed in tetragonal FeSe thin films is explained. It could be made controllable soon for spintronic applications

  5. Preparation of InSe Thin Films by Thermal Evaporation Method and Their Characterization: Structural, Optical, and Thermoelectrical Properties

    Directory of Open Access Journals (Sweden)

    Sarita Boolchandani

    2018-01-01

    Full Text Available The indium selenium (InSe bilayer thin films of various thickness ratios, InxSe(1-x (x = 0.25, 0.50, 0.75, were deposited on a glass substrate keeping overall the same thickness of 2500 Ǻ using thermal evaporation method under high vacuum atmosphere. Electrical, optical, and structural properties of these bilayer thin films have been compared before and after thermal annealing at different temperatures. The structural and morphological characterization was done using XRD and SEM, respectively. The optical bandgap of these thin films has been calculated by Tauc’s relation that varies within the range of 1.99 to 2.05 eV. A simple low-cost thermoelectrical power measurement setup is designed which can measure the Seebeck coefficient “S” in the vacuum with temperature variation. The setup temperature variation is up to 70°C. This setup contains a Peltier device TEC1-12715 which is kept between two copper plates that act as a reference metal. Also, in the present work, the thermoelectric power of indium selenide (InSe and aluminum selenide (AlSe bilayer thin films prepared and annealed in the same way is calculated. The thermoelectric power has been measured by estimating the Seebeck coefficient for InSe and AlSe bilayer thin films. It was observed that the Seebeck coefficient is negative for InSe and AlSe thin films.

  6. The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films

    Energy Technology Data Exchange (ETDEWEB)

    Goodwin, E.D.; Straus, Daniel B. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Gaulding, E. Ashley [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Murray, Christopher B. [Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Kagan, Cherie R., E-mail: kagan@seas.upenn.edu [Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States)

    2016-06-01

    Highlights: • Na{sub 2}Se and PbCl{sub 2} treatments modified the surface chemistry of PbSe quantum dots. • Excess Se (Pb) p-doped (n-doped) PbSe quantum dot thin films. • Carrier mobility and lifetime were studied using time-resolved microwave conductivity. • Mobility increased as the Fermi level approached the band edges. - Abstract: We used flash-photolysis, time-resolved microwave conductivity (TRMC) to probe the carrier mobility and lifetime in PbSe quantum dot (QD) thin films treated with solutions of the metal salts of Na{sub 2}Se and PbCl{sub 2}. The metal salt treatments tuned the Pb:Se stoichiometry and swept the Fermi energy throughout the QD thin film bandgap. A stoichiometric imbalance favoring excess Se heavily p-doped the QD thin film, shifted the Fermi energy toward the valence band, and yielded the highest TRMC mobility and lifetime. Introducing Pb first compensated the p-doping and shifted the Fermi level through mid-gap, decreasing the TRMC mobility. Further Pb addition created an excess of Pb, n-doped the QD thin film, moved the Fermi level to near the conduction band, and again increased the TRMC mobility. The increase in TRMC mobility as the Fermi energy was shifted toward the band edges by non-stoichiometry is consistent with the QD thin film density of states.

  7. Composition and growth procedure-dependent properties of electrodeposited CuInSe 2 thin films

    Science.gov (United States)

    Babu, S. Moorthy; Ennaoui, A.; Lux-Steiner, M. Ch.

    2005-02-01

    CuInSe 2 thin films were deposited on molybdenum-coated glass substrates by electrodeposition. Deposition was carried out with a variety of electrochemical bath compositions. The quality of the deposits depends very much on the source materials as well as the concentration of the same in the electrolyte. The deposition potential was varied from -0.4 to -0.75 V vs. SCE. The pH of the solution was adjusted to 1.5-2 using diluted sulphuric acid. Chloride salts containing bath yield good surface morphology, but there is always excess of the metallic content in the deposited films. Different growth procedures, like initial metallic layers of copper or indium, layers of copper selenide or indium selenide before the actual deposition of ternary chalcopyrite layers were attempted. Fabrication pathway, morphological and compositional changes due to the different precursor route has been analysed. The quality of the deposits prepared by one-step electrodeposition is better than the deposits with a two-stage process. The deposited films were characterized with XRD, SEM-EDAX, UV-visible spectroscopy and I- V characteristics. The deposited films were annealed in air as well as in nitrogen atmosphere. The influence of annealing temperature, environment and annealing time on the properties of the films are evaluated. Attempts were made to fabricate solar cell structure from the deposited absorber films. The structure of Mo/CuInSe 2/CdS/ZnO/Ni was characterized with surface, optical and electrical studies.

  8. Low-temperature photoluminescence of CuSe2 nano-objects in selenium thin films

    Directory of Open Access Journals (Sweden)

    Martina Gilić

    2017-06-01

    Full Text Available Thin films of CuSe2 nanoparticles embedded in selenium matrix were prepared by vacuum evaporation method on a glass substrate at room temperature. The optical properties of the films were investigated by photoluminescence spectroscopy (T=20-300K and UV-VIS spectroscopy (T = 300K. Surface morphology was investigated by scanning electron microscopy. The band gap for direct transition in CuSe2 was found to be in the range of 2.72-2.75 eV and that for indirect transition is in the range of 1.71-1.75 eV determined by UV-VIS spectroscopy. On the other hand, selenium exhibits direct band gap in the range of 2.33-2.36 eV. All estimated band gaps slightly decrease with the increase of the film thickness. Photoluminescence spectra of the thin films clearly show emission bands at about 1.63 and 2.32 eV at room temperature, with no shift observed with decreasing temperature. A model was proposed for explaining such anomaly.

  9. Study of sub band gap absorption of Sn doped CdSe thin films

    International Nuclear Information System (INIS)

    Kaur, Jagdish; Rani, Mamta; Tripathi, S. K.

    2014-01-01

    The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively

  10. Study of sub band gap absorption of Sn doped CdSe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Jagdish; Rani, Mamta [Department of Physics, Panjab University, Chandigarh- 160014 (India); Tripathi, S. K., E-mail: surya@pu.ac.in [Centre of Advanced Study in Physics, Panjab University, Chandigarh- 160014 (India)

    2014-04-24

    The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively.

  11. Dielectric Properties of Cd1-xZnxSe Thin Film Semiconductors

    International Nuclear Information System (INIS)

    Wahab, L.A.; Farrag, A.A.; Zayed, H.A.

    2012-01-01

    Cd 1-x Zn x Se (x=0, 0.5 and 1) thin films of thickness 300 nm have been deposited on highly cleaned glass substrates (Soda-lime glass) by thermal evaporation technique under pressure 10-5 Torr. The crystal structure, lattice parameters and grain size were determined from X-ray diffraction patterns of these films. The dielectric response and ac conductivity of the films are investigated in the frequency range from 80 Hz to 5 MHz and temperature range from 300 K to 420 K. AC conductivity increases linearly with the frequency according to the power relation σ a c (ψ)=A (ψ) s . The dielectric constant and loss show low values at high frequencies. The relaxation time t, resistance R and capacitance C were calculated from Nyquist diagram. The behavior can be modeled by an equivalent parallel RC circuit.

  12. Spin texture of Bi2Se3 thin films in the quantum tunneling limit.

    Science.gov (United States)

    Landolt, Gabriel; Schreyeck, Steffen; Eremeev, Sergey V; Slomski, Bartosz; Muff, Stefan; Osterwalder, Jürg; Chulkov, Evgueni V; Gould, Charles; Karczewski, Grzegorz; Brunner, Karl; Buhmann, Hartmut; Molenkamp, Laurens W; Dil, J Hugo

    2014-02-07

    By means of spin- and angle-resolved photoelectron spectroscopy we studied the spin structure of thin films of the topological insulator Bi2Se3 grown on InP(111). For thicknesses below six quintuple layers the spin-polarized metallic topological surface states interact with each other via quantum tunneling and a gap opens. Our measurements show that the resulting surface states can be described by massive Dirac cones which are split in a Rashba-like manner due to the substrate induced inversion asymmetry. The inner and the outer Rashba branches have distinct localization in the top and the bottom part of the film, whereas the band apices are delocalized throughout the entire film. Supported by calculations, our observations help in the understanding of the evolution of the surface states at the topological phase transition and provide the groundwork for the realization of two-dimensional spintronic devices based on topological semiconductors.

  13. Nanomechanical properties of GaSe thin films deposited on Si(1 1 1) substrates by pulsed laser deposition

    International Nuclear Information System (INIS)

    Jian, Sheng-Rui; Juang, Jenh-Yih; Luo, Chih-Wei; Ku, Shin-An; Wu, Kaung-Hsiung

    2012-01-01

    Highlights: ► GaSe thin films are grown by PLD. ► Structural properties of GaSe thin films are measured by XRD. ► Hardness and Young’s modulus of GaSe thin films are measured by nanoindentation. - Abstract: The correlations between the crystalline structure and mechanical properties of GaSe thin films were investigated by means of X-ray diffraction (XRD) and nanoindentation techniques. The GaSe thin films were deposited on Si(1 1 1) substrates deposited at various deposition temperatures using pulsed laser deposition (PLD). The XRD results indicate that all the GaSe thin films are pure hexagonal phase with highly (0 0 0 l)-oriented characteristics. Nanoindentation results revealed apparent discontinuities (so-called multiple “pop-in” events) in the load-displacement curve, while no discontinuity was observed in the unloading segment of the load-displacement curve. The hardness and Young’s modulus of GaSe thin films determined by the continuous stiffness measurements (CSM) method indicated that both mechanical parameters increased with the increasing deposition temperature with the hardness and the Young’s modulus being increased from 1.2 ± 0.1 to 1.8 ± 0.1 GPa and from 39.6 ± 1.2 to 68.9 ± 2.7 GPa, respectively, as the deposition temperature was raised from 400 to 475 °C. These results suggest that the increased grain size might have played a prominent role in determining the mechanical properties of the PLD-derived GaSe thin films.

  14. An investigation on silar Cu(In{sub 1-x}Al{sub x})Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dhanam, M. [PG and Research, Department of Physics, Kongunadu Arts and Science College, Coimbatore 641029 (India); Kavitha, B., E-mail: kavitha_48@yahoo.co.in [PG and Research, Department of Physics, Kongunadu Arts and Science College, Coimbatore 641029 (India); Velumani, S. [Centro de Investigacion y de Estudios Avanzados del I.P.N.(CINVESTAV) (Mexico)

    2010-10-25

    Cu(In{sub 1-x}Al{sub x})Se{sub 2} [CIAS] thin films were prepared for the first time by successive ionic layer adsorption and reaction [SILAR] method with two different dipping cycles. The thickness of the films was measured by gravimetric technique. The structural, morphological, compositional, optical transition and electrical investigation of SILAR CIAS thin films with respect to two different dipping cycles have been discussed in this paper.

  15. CuInSe2-Based Thin-Film Photovoltaic Technology in the Gigawatt Production Era

    Science.gov (United States)

    Kushiya, Katsumi

    2012-10-01

    The objective of this paper is to review current status and future prospect on CuInSe2 (CIS)-based thin-film photovoltaic (PV) technology. In CIS-based thin-film PV technology, total-area cell efficiency in a small-area (i.e., smaller than 1 cm2) solar cell with top grids has been over 20%, while aperture-area efficiency in a large-area (i.e., larger than 800 cm2 as definition) monolithic module is approaching to an 18% milestone. However, most of the companies with CIS-based thin-film PV technology still stay at a production research stage, except Solar Frontier K.K. In July, 2011, Solar Frontier has joined the gigawatt (GW) group by starting up their third facility with a 0.9-GW/year production capacity. They are keeping the closest position to pass a 16% module-efficiency border by transferring the developed technologies in the R&D and accelerating the preparation for the future based on the concept of a product life-cycle management.

  16. Characterization of Cu(In,Ga)(S,Se)2 thin films prepared by sequential evaporation from ternary compounds

    International Nuclear Information System (INIS)

    Yamaguchi, T.; Hatori, M.; Niiyama, S.; Miyake, Y.

    2006-01-01

    Cu(In,Ga)(S,Se) 2 thin films were fabricated by sequential evaporation from CuGaSe 2 , CuInSe 2 and In 2 S 3 compounds for photovoltaic device applications. From XRF analysis, the Cu:(In+Ga):(S+Se) atomic ratio in all thin films was approximately 1:1:2. As the [In 2 S 3 ]/([CuGaSe 2 ]+[CuInSe 2 ]) mole ratio in the evaporating materials increased, the S/(S+Se) atomic ratio in the thin films increased from 0 to 0.16 determined by XRF and to 0.43 by EPMA. XRD studies demonstrated that the prepared thin films had a chalcopyrite Cu(In,Ga) (S,Se) 2 structure and the preferred orientation to the 112 plane. The SEM images demonstrated that Cu(In,Ga)(S,Se) 2 thin films had large and columnar grains. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  17. Colloidal CuInSe2 nanocrystals thin films of low surface roughness

    Science.gov (United States)

    de Kergommeaux, Antoine; Fiore, Angela; Faure-Vincent, Jérôme; Pron, Adam; Reiss, Peter

    2013-03-01

    Thin-film processing of colloidal semiconductor nanocrystals (NCs) is a prerequisite for their use in (opto-)electronic devices. The commonly used spin-coating is highly materials consuming as the overwhelming amount of deposited matter is ejected from the substrate during the spinning process. Also, the well-known dip-coating and drop-casting procedures present disadvantages in terms of the surface roughness and control of the film thickness. We show that the doctor blade technique is an efficient method for preparing nanocrystal films of controlled thickness and low surface roughness. In particular, by optimizing the deposition conditions, smooth and pinhole-free films of 11 nm CuInSe2 NCs have been obtained exhibiting a surface roughness of 13 nm root mean square (rms) for a 350 nm thick film, and less than 4 nm rms for a 75 nm thick film. Invited talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology, 30 October-2 November 2012, Ha Long, Vietnam.

  18. Temperature-dependent magnetism of Fe thin films on ZnSe(0 0 1)

    International Nuclear Information System (INIS)

    Cantoni, M.; Bertacco, R.; Ciccacci, F.; Puppin, E.; Pinotti, E.; Brenna, M.; Marangolo, M.; Eddrieff, M.; Torelli, P.; Maccherozzi, F.; Fujii, J.; Panaccione, G.

    2007-01-01

    We present X-ray magnetic circular dichroism (XMCD) and magneto-optical Kerr effect (MOKE) data on the magnetic properties of Fe/ZnSe(0 0 1) thin films at increasing Fe coverage. The magnetic behaviour of the Fe overlayer is superparamagnetic for a coverage up to 6 monolayers whereas, above this threshold, a truly ferromagnetic phase shows up. XMCD and MOKE data show that this behaviour is substantially unchanged in the temperature range 10-300 K for all the investigated coverages: these findings imply that the blocking temperature is definitely below 10 K

  19. Photoelectrochemical water splitting using a Cu(In,Ga)Se{sub 2} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Daisuke; Minegishi, Tsutomu; Maeda, Kazuhiko; Katayama, Masao; Kubota, Jun; Domen, Kazunari [Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Yamada, Akira; Konagai, Makoto [Department of Physical Electronics, Graduate School of Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2010-06-15

    The effects of surface modification and reaction conditions on the photoelectrochemical properties of polycrystalline Cu(In,Ga)Se{sub 2} (CIGS) thin films for water splitting were studied. CIGS modified with platinum particles (Pt/CIGS) generated a cathodic photocurrent at potentials up to + 0.4 V vs. RHE at pH = 9.5. The photocurrent was stable for 16 h, which resulted in a turnover number of over 500. A CdS-inserted film (Pt/CdS/CIGS) had significantly improved properties compared to Pt/CIGS: a 0.3 V higher onset potential of cathodic photocurrent and a three-fold increase in the quantum efficiency. Our results suggest the feasibility of CIGS as a photocathode for biphotoelectrochemical water splitting. (author)

  20. Thickness dependent structural, optical and electrical properties of Se85In12Bi3 nanochalcogenide thin films

    Science.gov (United States)

    Tripathi, Ravi P.; Zulfequar, M.; Khan, Shamshad A.

    2018-04-01

    Our aim is to study the thickness dependent effects on structure, electrical and optical properties of Se85In12Bi3 nanochalcogenide thin films. Bulk alloy of Se85In12Bi3 was synthesized by melt-quenching technique. The amorphous as well as glassy nature of Se85In12Bi3 chalcogenide was confirmed by non-isothermal Differential Scanning Calorimetry (DSC) measurements. The nanochalcogenide thin films of thickness 30, 60 and 90 nm were prepared on glass/Si wafer substrate using Physical Vapour Condensation Technique (PVCT). From XRD studies it was found that thin films have amorphous texture. The surface morphology and particle size of films were studied by Field Emission Scanning Electron Microscope (FESEM). From optical studies, different optical parameters were estimated for Se85In12Bi3 thin films at different thickness. It was found that the absorption coefficient (α) and extinction coefficient (k) increases with photon energy and decreases with film thickness. The optical absorption process followed the rule of indirect transitions and optical band gap were found to be increase with film thickness. The value of Urbach energy (Et) and steepness parameter (σ) were also calculated for different film thickness. For electrical studies, dc-conductivity measurement was done at different temperature and activation energy (ΔEc) were determined and found to be increase with film thickness.

  1. Structural, optical and electrical properties of cadmium-doped lead chalcogenide (PbSe) thin films

    International Nuclear Information System (INIS)

    Khan, Shamshad A.; Khan, Zishan H.; El-Sebaii, A.A.; Al-Marzouki, F.M.; Al-Ghamdi, A.A.

    2010-01-01

    (PbSe) 100-x Cd x thin films of thickness 3000 A with variable concentrations of Cd (x=5, 10, 15 and 20) were prepared by thermal evaporation on glass substrates at room temperature at a base pressure of 10 -6 Torr. The structural, optical and electrical properties of these films were studied. X-ray diffraction patterns were used to determine the crystal structure of the films. Films were of polycrystalline texture over the whole range of study. Optical constants of all films were determined by absorbance and reflection measurements in a wavelength range 400-1200 nm. Analysis of the optical absorption data showed that the rule of direct transitions predominates. The values of the absorption coefficient (α), extinction coefficient (k) and imaginary part of the dielectric constant were found to increase with increasing Cd content in lead chalcogenides while the refractive index (n) and real part of dielectric constant were increased with increasing Cd concentration up to 15% and then they decreased with 20% of Cd content in PbSe. These results were interpreted in terms of the change in concentration of localized states due to the shift in Fermi level. The dc conductivities and activation energies of the films were measured in the temperature range 298-398 K. It was observed that the dc conductivity increases at all temperatures with the increase of Cd content in lead chalcogenide system. The experimental data suggests that the conduction is due to the thermally assisted tunneling of the carriers in the localized states near the band edges. The activation energy and optical band gap were found to decrease with increasing Cd concentration in lead chalcogenide.

  2. Thermoelectric Transport by Surface States in Bi2Se3-Based Topological Insulator Thin Films

    International Nuclear Information System (INIS)

    Li Long-Long; Xu Wen

    2015-01-01

    We develop a tractable theoretical model to investigate the thermoelectric (TE) transport properties of surface states in topological insulator thin films (TITFs) of Bi 2 Se 3 at room temperature. The hybridization between top and bottom surface states in the TITF plays a significant role. With the increasing hybridization-induced surface gap, the electrical conductivity and electron thermal conductivity decrease while the Seebeck coefficient increases. This is due to the metal-semiconductor transition induced by the surface-state hybridization. Based on these TE transport coefficients, the TE figure-of-merit ZT is evaluated. It is shown that ZT can be greatly improved by the surface-state hybridization. Our theoretical results are pertinent to the exploration of the TE transport properties of surface states in TITFs and to the potential application of Bi 2 Se 3 -based TITFs as high-performance TE materials and devices. (paper)

  3. Photo-galvanic effect in Bi2Se3 thin films with ionic liquid gating

    Science.gov (United States)

    Pan, Yu; Richardella, Anthony; Lee, Joon Sue; Flanagan, Thomas; Samarth, Nitin

    2013-03-01

    A key challenge in three dimensional (3D) topological insulators (TIs) is to reveal the helical spin-polarized surface states via electrical transport measurements. A recent study [Nature Nanotech. 7, 96 (2012)] showed that circularly polarized light can be used to generate and control photocurrents in the 3D TI Bi2Se3, even at photon energies that are well above the bulk band gap. Symmetry considerations suggest that this ``photo-galvanic effect'' arises purely from photo-currents induced in the surface Dirac states. To gain insights into this phenomenon, we have carried out systematic measurements of the photo-galvanic effect in electrically gated MBE-grown Bi2Se3 thin films of varying thickness. By using an ionic liquid as an optically transparent gate, we map out the behavior of the photo-galvanic effect as a function of Fermi energy over a temperature range 5 K <= T <= 300 K. Supported by ONR and NSF.

  4. Back surface studies of Cu(In,Ga)Se2 thin film solar cells

    Science.gov (United States)

    Simchi, Hamed

    Cu(In,Ga)Se2 thin film solar cells have attracted a lot of interest because they have shown the highest achieved efficiency (21%) among thin film photovoltaic materials, long-term stability, and straightforward optical bandgap engineering by changing relative amounts of present elements in the alloy. Still, there are several opportunities to further improve the performance of the Cu(In,Ga)Se2 devices. The interfaces between layers significantly affect the device performance, and knowledge of their chemical and electronic structures is essential in identifying performance limiting factors. The main goal of this research is to understand the characteristics of the Cu(In,Ga)Se2-back contact interface in order to design ohmic back contacts for Cu(In,Ga)Se2-based solar cells with a range of band gaps and device configurations. The focus is on developing either an opaque or transparent ohmic back contact via surface modification or introduction of buffer layers in the back surface. In this project, candidate back contact materials have been identified based on modeling of band alignments and surface chemical properties of the absorber layer and back contact. For the first time, MoO3 and WO 3 transparent back contacts were successfully developed for Cu(In,Ga)Se 2 solar cells. The structural, optical, and surface properties of MoO 3 and WO3 were optimized by controlling the oxygen partial pressure during reactive sputtering and post-deposition annealing. Valence band edge energies were also obtained by analysis of the XPS spectra and used to characterize the interface band offsets. As a result, it became possible to illuminate of the device from the back, resulting in a recently developed "backwall superstrate" device structure that outperforms conventional substrate Cu(In,Ga)Se2 devices in the absorber thickness range 0.1-0.5 microm. Further enhancements were achieved by introducing moderate amounts of Ag into the Cu(In,Ga)Se2 lattice during the co-evaporation method

  5. Opto-electrical energy conversion by thin electrolytic CdSe films on Ni substrates

    International Nuclear Information System (INIS)

    Glenis, G X; Athanassopoulou, M D; Argyropoulos, Th G; Dervos, C T

    2015-01-01

    Thin-films (300 nm) of zinc-blende (cubic structure) CdSe (111) electrolytically deposited on nickel substrates had their surface characteristics investigated by XRD, SEM, and profilometry scans. A metal-CdSe-metal structure was formed by positioning a Au electrode on top of CdSe and the I–V characteristics of the resulting device were investigated in the dark and under low intensities (≤0.2 mW cm −2 ) of diffused solar radiation. The experimental results show that the illuminated structure is an active device that produces electric power in the 2nd quadrant of the I–V curve. This response may be related to the Ni-to-CdSe interface, where carriers are effectively generated as a result of deep energy level formations, spatially confined in the interfacial region of the depletion layer width of the Ni-CdSe junction. A potential energy diagram is proposed to present the spatially and energetically confined deep-level parameters, the operation principles (carrier generation and transport processes) across the structure and link them to the obtained I–V response. A mathematical modeling based on the Schokley-Read-Hall recombination theory confirms the experimentally obtained current profiles of illuminated junctions. Such opto-electrical tranducers might be implemented in multilayer photovoltaic hetero-structures to enhance their conversion efficiencies and reduce their operating temperatures. (paper)

  6. Opto-electrical energy conversion by thin electrolytic CdSe films on Ni substrates

    Science.gov (United States)

    Glenis, G. X.; Athanassopoulou, M. D.; Argyropoulos, Th G.; Dervos, C. T.

    2015-02-01

    Thin-films (300 nm) of zinc-blende (cubic structure) CdSe (111) electrolytically deposited on nickel substrates had their surface characteristics investigated by XRD, SEM, and profilometry scans. A metal-CdSe-metal structure was formed by positioning a Au electrode on top of CdSe and the I-V characteristics of the resulting device were investigated in the dark and under low intensities (≤0.2 mW cm-2) of diffused solar radiation. The experimental results show that the illuminated structure is an active device that produces electric power in the 2nd quadrant of the I-V curve. This response may be related to the Ni-to-CdSe interface, where carriers are effectively generated as a result of deep energy level formations, spatially confined in the interfacial region of the depletion layer width of the Ni-CdSe junction. A potential energy diagram is proposed to present the spatially and energetically confined deep-level parameters, the operation principles (carrier generation and transport processes) across the structure and link them to the obtained I-V response. A mathematical modeling based on the Schokley-Read-Hall recombination theory confirms the experimentally obtained current profiles of illuminated junctions. Such opto-electrical tranducers might be implemented in multilayer photovoltaic hetero-structures to enhance their conversion efficiencies and reduce their operating temperatures.

  7. Preparation and characterization of CuInSe2 particles via the hydrothermal route for thin-film solar cells

    International Nuclear Information System (INIS)

    Wu, Chung-Hsien; Chen, Fu-Shan; Lin, Shin-Hom; Lu, Chung-Hsin

    2011-01-01

    Highlights: → A new hydrothermal process for preparing copper indium diselenide (CuInSe 2 ). → Well-crystallized CuInSe 2 particles are obtained at 180 deg. C for 1 h. → Densified CuInSe 2 thin films are prepared from ink printing. → Increasing temperatures result in an improvement of properties of CuInSe 2 films. - Abstract: CuInSe 2 powders with a chalcopyrite structure used in thin-film solar cells were successfully prepared via a hydrothermal method at low temperatures within short durations. Well-crystallized CuInSe 2 particles were formed via the hydrothermal reaction at 180 deg. C for 1 h. The concentrations of stabilizer, triethanolamine (TEA), significantly affected the purity, morphology and particle sizes of the prepared powders. Increasing the reaction duration and temperatures led to decrease the amount of second phase In(OH) 3 and resulted in the formation of pure CuInSe 2 . Densified CuInSe 2 thin films were prepared from ink printing with the addition of the flux. Increasing the selenization temperatures increased the grain size and improved the crystallinity of CuInSe 2 films.

  8. Optical spectroscopy, optical conductivity, dielectric properties and new methods for determining the gap states of CuSe thin films

    International Nuclear Information System (INIS)

    Sakr, G.B.; Yahia, I.S.; Fadel, M.; Fouad, S.S.; Romcevic, N.

    2010-01-01

    Research highlights: → The structural, optical dispersion parameters and the Raman spectroscopy have been studied for CuSe thin films. → X-ray diffraction results indicate the amorphous nature of the thermally evaporated CuSe thin films. → The refractive index shows an anomalous dispersion at the lower wavelength (absorption region) and a normal dispersion at the higher wavelengths (transparent region). → The refractive index dispersion obeys the single oscillator model proposed by Wemple and DiDomenico WDD model and the single oscillator parameters were determined. → The band gap of CuSe thin films was determined by three novel methods i.e. (relaxation time, real and imaginary dielectric constant and real and imaginary optical conductivity) which in a good agreement with the Tauc band gap value. - Abstract: The paper describes the structural and optical properties of CuSe thin films. X-ray diffraction pattern indicates that CuSe thin film has an amorphous structure. Transmittance T(λ) and reflectance R(λ) measurements in the wavelength range (300-1700 nm) were used to calculate the refractive index n(λ), the absorption index and the optical dispersion parameters according to Wemple and Didomenico WDD model. The dispersion curve of the refractive index shows an anomalous dispersion in the absorption region and a normal dispersion in the transparent region. The optical bandgap has been estimated and confirmed by four different methods. The value for the direct bandgap for the as-deposited CuSe thin film approximately equals 2.7 eV. The Raman spectroscopy was used to identify and quantify the individual phases presented in the CuSe films.

  9. Optical properties of Cd Se thin films obtained by pyrolytic dew; Propiedades opticas de peliculas delgadas de CdSe obtenidas por rocio pirolitico

    Energy Technology Data Exchange (ETDEWEB)

    Perez G, A.M. [UPAEP, 72160 Puebla (Mexico); Tepantlan, C.S. [UPT, 43626 Tulancingo, Hidalgo (Mexico); Renero C, F. [INAOE, 72840 Puebla (Mexico)

    2006-07-01

    In this paper the optical properties of Cd Se thin films obtained by spray pyrolysis are presented. The films are prepared by Sodium Seleno sulphate (Na{sub 2}SSeO{sub 3}) and Cadmium Chloride (CdC{sub 12}) mixing in aqueous environment. Optical parameters of the films (refractive index, absorption coefficient and optical ban gap) were calculated from transmittance spectra. The obtained values of the optical ban gap are compared with the result obtained by other deposition method. (Author)

  10. Photoelectrochemical properties of In{sub 2}Se{sub 3} thin films: Effect of substrate temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Abhijit A., E-mail: aay_physics@yahoo.co.in [Thin Film Physics Laboratory, Department of Physics, Electronics and Photonics, Rajarshi Shahu Mahavidyalaya, Latur, M.S. 413512 (India); Salunke, S.D. [Department of Chemistry and Analytical Chemistry, Rajarshi Shahu Mahavidyalaya, Latur, M.S. 413512 (India)

    2015-08-15

    Highlights: • Photoelectrochemical properties of In{sub 2}Se{sub 3} thin films. • In{sub 2}Se{sub 3} films are of n-type with I{sub sc} and V{sub oc} of 1.05 mA/cm{sup 2} and 261 mV respectively. • Efficiency (η) and fill factor (FF) is found to be 0.71% and 0.51% respectively. • Performance of cell can motivate further studies concerning solar energy conversion. - Abstract: In{sub 2}Se{sub 3} thin films have been deposited onto fluorine doped tin oxide coated (FTO) glass substrates at various substrate temperatures by spray pyrolysis. The photoelectrochemical cell configurations were In{sub 2}Se{sub 3} thin film/1 M (NaOH + Na{sub 2}S + S)/C. From capacitance–voltage (C–V) and current–voltage (I–V) characteristics; it is concluded that In{sub 2}Se{sub 3} thin films are of n-type. The Fill factor (FF) and solar conversion efficiency (η) were calculated from photovoltaic power output characteristics. In this instance, the highest measured photocurrent density of 1.05 mA/cm{sup 2} and open circuit voltage of 261 mV is observed for film deposited at 350 °C resulting in maximum power conversion efficiency (η) and fill factor (FF) to be 0.71% and 0.51% respectively. Electrochemical impedance spectroscopy study shows that the In{sub 2}Se{sub 3} film deposited at 350 °C shows better performance in photoelectrochemical cell. The performance of indium selenide thin film observed in our work can motivate further studies concerning solar energy conversion.

  11. Optical properties of electrochemically deposited CuInSe sub 2 thin films

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, C; Herrero, J [Inst. de Energias Renovables (CIEMAT), Madrid (Spain)

    1991-11-01

    Polycrystalline thin films of CuInSe{sub 2} within a wide composition range have been electrochemically deposited. Their optical properties in the near-infrared and visible range, 400-2000 nm, have been studied in relation to the deposition potential and film thickness. An absorption coefficient ({alpha}) as high as 10{sup 5} cm{sup -1} is observed at short wavelength ({lambda} < 700 nm), but near the band edge {alpha} has a value about 10{sup 4} cm{sup -1}. The observed absorption coefficient variation is due to an allowed direct transition with an energy in the range 0.88-0.96 eV and an additional forbidden direct transition with an energy in the range 1.32-1.41 eV, where the absorption coefficient depends on the deposition potential, and the possible phase nature of the material, with band gap narrowing when the potential becomes anodic. The values of {alpha} and transition energies also depend on the film thickness for samples up to 0.6 {mu}m thick. (orig.).

  12. Optical, electrical and the related parameters of amorphous Ge-Bi-Se thin films

    International Nuclear Information System (INIS)

    El-Korashy, A.; El-Kabany, N.; El-Zahed, H.

    2005-01-01

    The related optical and electrical parameters of amorphous Ge-Bi-Se thin films were studied. The dependence of optical and electrical properties on the Bi content was observed in most compositions. At Bi >10at% the behavior show a switch from p to n type conduction mechanism. The correlation between the optical band gap E g and the average heats of atomization H s were observed. The results indicated that both the number of topological constant N con and the radial and angular N α , N β valence force constants exhibit the same trend with increasing Bi content. On the other hand, the mean bond energy increases with increasing Bi content to x=15at%. It may be concluded that is a function of the mean coordination number N co , the type of bonds, the degree of cross-linking and the band energy forming the network

  13. Photoconductivity of Se85-xTe15Hgx thin films

    International Nuclear Information System (INIS)

    Chaudhary, Neetu; Bahishti, Adam A.; Zulfequar, M.

    2012-01-01

    The photoconductive properties such as dark conductivity, steady state and transient characteristics of a-Se 85-x Te 15 Hg x thin films, prepared by thermal vacuum evaporation technique have been studied in the temperature range 312-380 K. Analysis of data shows that the activation energy of dark current is greater as compared to the activation energy of photocurrent. The activation energy increases at higher concentration of Hg which shows that the defect density of states decreases. Analysis of intensity dependent photoconductivity shows that the bimolecular recombination is predominant. The transient photoconductivity shows that the carrier lifetime decreases with the increase in Hg concentration and increases at higher concentration of Hg. This decrease is due to the transition trapping process. Further the photosensitivity and carrier lifetime increases at higher concentration of Hg which also confirms that the density of defect states decreases.

  14. Electrodeposition of nanocrystalline CdSe thin films from dimethyl sulfoxide solution: Nucleation and growth mechanism, structural and optical studies

    International Nuclear Information System (INIS)

    Henriquez, R.; Badan, A.; Grez, P.; Munoz, E.; Vera, J.; Dalchiele, E.A.; Marotti, R.E.; Gomez, H.

    2011-01-01

    Highlights: → Electrodeposition of CdSe nanocrystalline semiconductor thin films. → Polycrystalline wurtzite structure with a slight (1010) preferred orientation. → Absorption edge shifts in the optical properties due to quantum confinement effects. - Abstract: Cadmium selenide (CdSe) nanocrystalline semiconductor thin films have been synthesized by electrodeposition at controlled potential based in the electrochemical reduction process of molecular selenium in dimethyl sulfoxide (DMSO) solution. The nucleation and growth mechanism of this process has been studied. The XRD pattern shows a characteristic polycrystalline hexagonal wurtzite structure with a slight (1 0 1 0) crystallographic preferred orientation. The crystallite size of nanocrystalline CdSe thin films can be simply controlled by the electrodeposition potential. A quantum size effect is deduced from the correlation between the band gap energy and the crystallite size.

  15. Flexible Cu(In,Ga)Se2 thin-film solar cells for space application

    International Nuclear Information System (INIS)

    Otte, Karsten; Makhova, Liudmila; Braun, Alexander; Konovalov, Igor

    2006-01-01

    Thin film solar cells (TFSC) with Cu(In,Ga)Se 2 (CIGS) as absorber layer have been produced on rigid glass substrates for the terrestrial market. There exist, however, different investigations for manufacturing of TFSC on flexible substrates in order to achieve very thin and highly flexible (rollable) solar cells. Besides their capability to open new terrestrial market segments, they are considered as competitive candidates for future flexible thin film space power generators compared to traditional crystalline solar cells. This paper explains the advantages of flexible TFSC for usage in space, including:-low mass and storage volume, -high power/mass ratio [>100 W/kg at array level], -high radiation resistance against proton and electron radiation and, -lower production costs. These cells can be produced on flexible conductive and insulating substrate materials and have efficiency potentials of up to 15%. We report on the current development steps to adopt the TFSC technology to space requirements as well as the first European industrial approach to the roll-to-roll production of flexible CIGS-TFSC on polyimide as substrate material. Stability issues in space environment concern not only the TFSC itself, but all system components such as interconnects, cell assembly and flexible blankets. The adhesion of the back-contact to the substrate, the emissivity control in the infrared wavelength range, the electrical contacting and interconnection as well as flexible encapsulation are currently under investigation and are discussed in the paper. The production costs for TFSC for space application can be further reduced by sharing resources for the production of flexible TFSC for the terrestrial market; namely by using both, the existing terrestrial investment in production facilities as well as the synergies in R and D

  16. Optical properties change in Te diffused As{sub 50}Se{sub 50} chalcogenide thin film

    Energy Technology Data Exchange (ETDEWEB)

    Naik, Ramakanta; Behera, M.; Panda, R.; Mishra, N. C. [Department of Physics, Utkal University, Bhubaneswar, 751004, Odisha (India)

    2016-05-23

    In the present report, we present the effect of Te diffusion into As{sub 50}Se{sub 50} thin film which changes the optical properties. The Te/As{sub 50}Se{sub 50} film was irradiated by a laser beam of 532 nm to study the diffusion mechanism due to photo induced effect. The As{sub 50}Se{sub 50}, Te/As{sub 50}Se{sub 50} films show a completely amorphous nature from X-ray diffraction study. A non direct transition was found for these films on the basis of optical transmission data carried out by Fourier Transform infrared Spectroscopy. The optical bandgap is found to be decreased with Te deposition and photo darkening phenomena is observed for the diffused film. The change in the optical constants are well supported by the corresponding change in different types of bonds which are being studied by X-ray photoelectron spectroscopy.

  17. Thickness-dependent dispersion parameters, energy gap and nonlinear refractive index of ZnSe thin films

    International Nuclear Information System (INIS)

    Prakash, Deo; Shaaban, E.R.; Shapaan, M.; Mohamed, S.H.; Othman, A.A.; Verma, K.D.

    2016-01-01

    Highlights: • Combined experimental and theoretical researches on ZnSe Thin Films. • The film thickness and refractive index were determined using envelope method. • The absorption coefficient and the energy gap were calculated. • Dispersion parameters were determined using Wemple-DiDomenico relation. • The third order susceptibility and nonlinear refractive index were calculated. - Abstract: Zinc selenide (ZnSe) thin films with different thicknesses were evaporated onto glass substrates using the thermal evaporation technique. X-ray diffraction analysis confirmed that both the film and powder have cubic zinc-blende structure. The fundamental optical parameters like absorption coefficient, extinction coefficient and band gap were evaluated in transparent region of transmittance and reflectance spectrum. The optical transition of the films was found to be allowed, where the energy gap increased from 2.576 to 2.702 eV with increasing film thickness. Also, the refractive index value increase with increasing film thickness. The refractive indices evaluated through envelope method were extrapolated by Cauchy dispersion relationship over the whole spectra range. Additionally, the dispersion of refractive index was determined in terms of Wemple-DiDomenico single oscillator model. Third order susceptibility and nonlinear refractive index were determined for different thickness of ZnSe thin films.

  18. Thickness-dependent dispersion parameters, energy gap and nonlinear refractive index of ZnSe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, Deo [School of Computer Science & Engineering, Faculty of Engineering, SMVD University, Kakryal, Katra 182320, J& K (India); Shaaban, E.R., E-mail: esam_ramadan2008@yahoo.com [Physics Department, Faculty of Science, Al-Azhar University, Assiut 71542 (Egypt); Shapaan, M. [Department of Physics, Faculty of Science, Al-Azahar University, Cairo (Egypt); Mohamed, S.H. [Physics Department, Faculty of Science, Sohag University, 82524 Sohag (Egypt); Othman, A.A. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Verma, K.D., E-mail: kdverma1215868@gmail.com [Material Science Research Laboratory, Department of Physics, S. V. College, Aligarh 202001, U.P. (India)

    2016-08-15

    Highlights: • Combined experimental and theoretical researches on ZnSe Thin Films. • The film thickness and refractive index were determined using envelope method. • The absorption coefficient and the energy gap were calculated. • Dispersion parameters were determined using Wemple-DiDomenico relation. • The third order susceptibility and nonlinear refractive index were calculated. - Abstract: Zinc selenide (ZnSe) thin films with different thicknesses were evaporated onto glass substrates using the thermal evaporation technique. X-ray diffraction analysis confirmed that both the film and powder have cubic zinc-blende structure. The fundamental optical parameters like absorption coefficient, extinction coefficient and band gap were evaluated in transparent region of transmittance and reflectance spectrum. The optical transition of the films was found to be allowed, where the energy gap increased from 2.576 to 2.702 eV with increasing film thickness. Also, the refractive index value increase with increasing film thickness. The refractive indices evaluated through envelope method were extrapolated by Cauchy dispersion relationship over the whole spectra range. Additionally, the dispersion of refractive index was determined in terms of Wemple-DiDomenico single oscillator model. Third order susceptibility and nonlinear refractive index were determined for different thickness of ZnSe thin films.

  19. thin films

    Indian Academy of Sciences (India)

    microscopy (SEM) studies, respectively. The Fourier transform ... Thin films; chemical synthesis; hydrous tin oxide; FTIR; electrical properties. 1. Introduction ... dehydrogenation of organic compounds (Hattori et al 1987). .... SEM images of (a) bare stainless steel and (b) SnO2:H2O thin film on stainless steel substrate at a ...

  20. Effect of substrate temperature on ac conduction properties of amorphous and polycrystalline GaSe thin films

    International Nuclear Information System (INIS)

    Thamilselvan, M.; PremNazeer, K.; Mangalaraj, D.; Narayandass, Sa.K.; Yi, Junsin

    2004-01-01

    X-ray diffraction analysis of GaSe thin films used in the present investigation showed that the as-deposited and the one deposited at higher substrate temperature are in amorphous and polycrystalline state, respectively. The alternating current (ac) conduction properties of thermally evaporated films of GaSe were studied ex situ employing symmetric aluminium ohmic electrodes in the frequency range of 120-10 5 Hz at various temperature regimes. For the film deposited at elevated substrate temperature (573 K) the ac conductivity was found to increase with improvement of its crystalline structure. The ac conductivity (σ ac ) is found to be proportional to (ω s ) where s m calculated from ac conductivity measurements are compared with optical studies of our previous reported work for a-GaSe and poly-GaSe thin films. The distance between the localized centres (R), activation energy (ΔE σ ) and the number of sites per unit energy per unit volume N(E F ) at the Fermi level were evaluated for both a-GaSe and poly-GaSe thin films. Goswami and Goswami model has been invoked to explain the dependence of capacitance on frequency and temperature

  1. Efficiency limitations of polycrystalline thin film solar cells: case of Cu(In,Ga)Se2

    International Nuclear Information System (INIS)

    Werner, Juergen H.; Mattheis, Julian; Rau, Uwe

    2005-01-01

    Small-area Cu(In,Ga)Se 2 thin film solar cells have reached more than 19% efficiencies. Compared to other polycrystalline materials this efficiency value is remarkable. Nevertheless, the 19% for Cu(In,Ga)Se 2 range more than 6% (absolute) below the world's best single-crystalline Si cells and almost 14% below the upper theoretical limit of 33% for an ideal black body cell with infinitely large mobility and radiative recombination only. About 4% out of the 14% are of optical nature, additional 3% stem from the limited mobility/diffusion length and from band gap fluctuations with a standard deviation no. sigmano. g no. approxno. 50 meV due to spatial variations of composition and stoichiometry of the quaternary compound Cu(In,Ga)Se 2 . Thus, about 26% efficiency would be possible if there were only these band gap fluctuations. Additional, voltage-dependent electrostatic potential fluctuations push down the efficiency further to 19%: The polycrystalline Cu(In,Ga)Se 2 which is unavoidably structurally inhomogeneous due to dislocations, grain boundaries, point defects, etc. is also electrostatically inhomogeneous because of charged defects. Electrostatic potential fluctuations at the valence and conduction band edge may be not only responsible for a high saturation current density but also for the ideality factor in the current/voltage curve. The band gap and electrostatic potential fluctuations make the effective band gap which controls the intrinsic carrier density smaller than the average optical gap. The (zero bias) electrostatic potential fluctuations are here derived from the ideality factors of the current/voltage curve. The ideality factor reflects the voltage-induced electrostatic homogenization of the sample. For the world's best Cu(In,Ga)Se 2 cells with an ideality factor of n id =1.5, we estimate zero bias electrostatic potential fluctuations with a standard deviation no. sigmano. elec no. approxno. 140 meV

  2. Study of the mobility activation in ZnSe thin films deposited using inert gas condensation

    Directory of Open Access Journals (Sweden)

    Jeewan Sharma

    2017-12-01

    Full Text Available ZnSe thin films were synthesized on glass substrates using the inert gas condensation technique at substrate temperature ranging from 25 °C to 100 °C. The hexagonal structure and average crystallite size (6.1–8.4 nm were determined from X-ray diffraction data. The transient photoconductivity was investigated using white light of intensity 8450 lx to deduce the effective density of states (Neff in the order of 1.02 × 1010–13.90 × 1010 cm−3, the frequency factor (S in the range 2.5 × 105–24.6 × 105 s−1 and the trap depth (E ranging between 0.37–0.64 eV of these films. The trap depth study revealed three different types of levels with quasi-continuous distribution below the conduction band. An increase in the photoconductivity was observed as a result of the formation of potential barriers (Vb and of the increase of carrier mobility at the crystallite boundaries. The study of the dependence of various mobility activation parameters on the deposition temperature and the crystallite size has provided better understanding of the mobility activation mechanism.

  3. Preparation and characterization of co-evaporated Cu{sub 2}ZnGeSe{sub 4} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Uday Bhaskar, P.; Suresh Babu, G.; Kishore Kumar, Y.B.; Sundara Raja, V., E-mail: sundararajav@rediffmail.com

    2013-05-01

    Cu{sub 2}ZnGeSe{sub 4} (CZGSe), a member of Cu{sub 2}–II–IV–VI{sub 4} family, is a promising material for solar cell absorber layer in thin film heterojunction solar cells like Cu{sub 2}ZnSnS{sub 4} and Cu{sub 2}ZnSnSe{sub 4} which have been explored in recent years as alternate to CuInGaSe{sub 2} solar cells. The effect of substrate temperature (523 K–723 K) on the growth of CZGSe films is investigated by studying their structural, morphological and optical properties. Raman spectroscopy studies have been done to identify the phases in addition to X-ray diffraction studies. CZGSe films deposited at different substrate temperatures and annealed at 723 K in selenium atmosphere are Cu-rich and Ge-poor and contained secondary phases Cu{sub (2−x)}Se and ZnSe. CZGSe films obtained by reducing the starting Cu mass by 10% were found to be single phase with stannite structure, the lattice parameters being a = 0.563 nm, c = 1.101 nm. The direct optical band gap of CZGSe films is found to be 1.63 eV which is close to ideal band gap of 1.50 eV for the highest photovoltaic conversion efficiency. The films are found to be p-type. - Highlights: • Synthesis of Cu{sub 2}ZnGeSe{sub 4} films for solar cell absorber layer • Effect of substrate temperature on the growth of co-evaporated Cu{sub 2}ZnGeSe{sub 4} films • X-ray diffraction, Raman and morphological studies of Cu{sub 2}ZnGeSe{sub 4} thin films.

  4. Investigation of the structural, optical and electrical transport properties of n-doped CdSe thin films

    Science.gov (United States)

    Ali, H. M.; Abd El-Ghanny, H. A.

    2008-04-01

    Thin films of (CdSe)90(In2O3)10, (CdSe)90(SnO2)10 and (CdSe)90(ZnO)10 have been grown on glass substrates by the electron beam evaporation technique. It has been found that undoped and Sn or In doped CdSe films have two direct transitions corresponding to the energy gaps Eg and Eg+Δ due to spin-orbit splitting of the valence band. The electrical resistivity for n-doped CdSe thin films as a function of light exposure time has been studied. The influence of doping on the structural, optical and electrical characteristics of In doped CdSe films has been investigated in detail. The lattice parameters, grain size and dislocation were determined from x-ray diffraction patterns. The optical transmittance and band gap of these films were determined using a double beam spectrophotometer. The DC conductivity of the films was measured in vacuum using a two-probe technique.

  5. Annealing effects on the photoresponse properties of CdSe nanocrystal thin films

    International Nuclear Information System (INIS)

    Lou Shiyun; Zhou Changhua; Wang Hongzhe; Shen Huaibin; Cheng Gang; Du Zuliang; Zhou, Shaomin; Li Linsong

    2011-01-01

    Highlights: → The as-prepared CdSe nanocrystal films were treated at 500 deg. C for 3 h under continuous N 2 . → Annealing process removed the organic capping completely and eliminated oxide on the CdSe surface. → Thermal annealing resulted the increase of the crystallite sizes and necking the NCs. → The photoresponse speed of the CdSe nanocrystal films was improved. - Abstract: The photoresponse properties of the as-prepared and annealed close-packed CdSe nanocrystal (NC) films were investigated under laser illumination by Kelvin probe force microscopy. The annealing process improved the photoresponse speed of the CdSe NC films. The work function of the annealed CdSe NC films changed more rapidly than that of the non-annealed film in air at room temperature. Combined with X-ray photoelectron spectroscopy measurements and thermogravimetric analysis, the observed phenomena can be interpreted that annealing process removed the organic capping agents completely and eliminated oxide on the CdSe surface, which formed the tunnel barrier between NCs in the CdSe NC films. Consequently, it improved the separation rate of photoelectric charges and thus provided high speed photoresponse.

  6. All-metallic electrically gated 2H-TaSe2 thin-film switches and logic circuits

    International Nuclear Information System (INIS)

    Renteria, J.; Jiang, C.; Yan, Z.; Samnakay, R.; Goli, P.; Pope, T. R.; Salguero, T. T.; Wickramaratne, D.; Lake, R. K.; Khitun, A. G.; Balandin, A. A.

    2014-01-01

    We report the fabrication and performance of all-metallic three-terminal devices with tantalum diselenide thin-film conducting channels. For this proof-of-concept demonstration, the layers of 2H-TaSe 2 were exfoliated mechanically from single crystals grown by the chemical vapor transport method. Devices with nanometer-scale thicknesses exhibit strongly non-linear current-voltage characteristics, unusual optical response, and electrical gating at room temperature. We have found that the drain-source current in thin-film 2H-TaSe 2 –Ti/Au devices reproducibly shows an abrupt transition from a highly resistive to a conductive state, with the threshold tunable via the gate voltage. Such current-voltage characteristics can be used, in principle, for implementing radiation-hard all-metallic logic circuits. These results may open new application space for thin films of van der Waals materials

  7. All-metallic electrically gated 2H-TaSe2 thin-film switches and logic circuits

    Science.gov (United States)

    Renteria, J.; Samnakay, R.; Jiang, C.; Pope, T. R.; Goli, P.; Yan, Z.; Wickramaratne, D.; Salguero, T. T.; Khitun, A. G.; Lake, R. K.; Balandin, A. A.

    2014-01-01

    We report the fabrication and performance of all-metallic three-terminal devices with tantalum diselenide thin-film conducting channels. For this proof-of-concept demonstration, the layers of 2H-TaSe2 were exfoliated mechanically from single crystals grown by the chemical vapor transport method. Devices with nanometer-scale thicknesses exhibit strongly non-linear current-voltage characteristics, unusual optical response, and electrical gating at room temperature. We have found that the drain-source current in thin-film 2H-TaSe2-Ti/Au devices reproducibly shows an abrupt transition from a highly resistive to a conductive state, with the threshold tunable via the gate voltage. Such current-voltage characteristics can be used, in principle, for implementing radiation-hard all-metallic logic circuits. These results may open new application space for thin films of van der Waals materials.

  8. All-metallic electrically gated 2H-TaSe{sub 2} thin-film switches and logic circuits

    Energy Technology Data Exchange (ETDEWEB)

    Renteria, J.; Jiang, C.; Yan, Z. [Nano-Device Laboratory, Department of Electrical Engineering, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Samnakay, R.; Goli, P. [Materials Science and Engineering Program, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Pope, T. R.; Salguero, T. T. [Department of Chemistry, University of Georgia, Athens, Georgia 30602 (United States); Wickramaratne, D.; Lake, R. K. [Laboratory for Terascale and Terahertz Electronics, Department of Electrical Engineering, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Khitun, A. G. [Nano-Device Laboratory, Department of Electrical Engineering, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Materials Science and Engineering Program, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Balandin, A. A., E-mail: balandin@ee.ucr.edu [Nano-Device Laboratory, Department of Electrical Engineering, Bourns College of Engineering, University of California–Riverside, Riverside, California 92521 (United States); Department of Chemistry, University of Georgia, Athens, Georgia 30602 (United States)

    2014-01-21

    We report the fabrication and performance of all-metallic three-terminal devices with tantalum diselenide thin-film conducting channels. For this proof-of-concept demonstration, the layers of 2H-TaSe{sub 2} were exfoliated mechanically from single crystals grown by the chemical vapor transport method. Devices with nanometer-scale thicknesses exhibit strongly non-linear current-voltage characteristics, unusual optical response, and electrical gating at room temperature. We have found that the drain-source current in thin-film 2H-TaSe{sub 2}–Ti/Au devices reproducibly shows an abrupt transition from a highly resistive to a conductive state, with the threshold tunable via the gate voltage. Such current-voltage characteristics can be used, in principle, for implementing radiation-hard all-metallic logic circuits. These results may open new application space for thin films of van der Waals materials.

  9. Hydrogen effects on deep level defects in proton implanted Cu(In,Ga)Se{sub 2} based thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.W.; Seol, M.S.; Kwak, D.W.; Oh, J.S. [Department of Physics, Dongguk University, Seoul 100-715 (Korea, Republic of); Jeong, J.H. [Photo-electronic Hybrids Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Cho, H.Y., E-mail: hycho@dongguk.edu [Department of Physics, Dongguk University, Seoul 100-715 (Korea, Republic of)

    2012-08-01

    Hydrogen effects on deep level defects and a defect generation in proton implanted Cu(In,Ga)Se{sub 2} (CIGS) based thin films for solar cell were investigated. CIGS films with a thickness of 3 {mu}m were grown on a soda-lime glass substrate by a co-evaporation method, and then were implanted with protons. To study deep level defects in the proton implanted CIGS films, deep level transient spectroscopy measurements on the CIGS-based solar cells were carried out, these measurements found 6 traps (including 3 hole traps and 3 electron traps). In the proton implanted CIGS films, the deep level defects, which are attributed to the recombination centers of the CIGS solar cell, were significantly reduced in intensity, while a deep level defect was generated around 0.28 eV above the valence band maximum. Therefore, we suggest that most deep level defects in CIGS films can be controlled by hydrogen effects. - Highlights: Black-Right-Pointing-Pointer Proton implanted Cu(In,Ga)Se{sub 2} thin film and solar cell are prepared. Black-Right-Pointing-Pointer Deep level defects of Cu(In,Ga)Se{sub 2} thin film and solar cell are investigated. Black-Right-Pointing-Pointer Hydrogenation using proton implantation and H{sub 2} annealing reduces deep level defects. Black-Right-Pointing-Pointer Hydrogenation could enhance electrical properties and efficiency of solar cells.

  10. Sub-band-gap absorption of Cu(In,Ga)Se{sub 2} thin film semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Meessen, Max; Brueggemann, Rudolf; Bauer, Gottfried H. [Carl von Ossietzky University Oldenburg (Germany)

    2012-07-01

    The sub-band-gap absorption of Cu(In,Ga)Se{sub 2} thin films has been studied by photothermal deflection spectroscopy (PDS) in conjunction with optical transmittance spectroscopy. The resulting absorption coefficients are compared to those calculated from photoluminescence spectra using Planck's generalized law. Quantities related to the absorption like Urbach energy and defect densities are derived from the absorption curves. This concept has been applied to a series of bromine-methanol etched Cu(In{sub x-1},Ga{sub x})Se{sub 2} (x=0.3) absorbers with varying thicknesses. A shift in the band gap is observed with both methods and can be related to the gallium gradient in the samples. In contrast, the Urbach energy and defect absorption values are not substantially affected by the etching process. The influence of CdS buffer layers or highly thermally conductive metallic back contacts on PDS results is studied by measuring nominally identical samples with and without those layers.

  11. Generation of electrical defects in ion beam assisted deposition of Cu(In,Ga)Se2 thin film solar cells

    International Nuclear Information System (INIS)

    Zachmann, H.; Puttnins, S.; Daume, F.; Rahm, A.; Otte, K.

    2011-01-01

    Thin films of Cu(In,Ga)Se 2 (CIGS) absorber layers for thin film solar cells have been manufactured on polyimide foil in a low temperature, ion beam assisted co-evaporation process. In the present work a set of CIGS thin films was produced with varying selenium ion energy. Solar cell devices have been manufactured from the films and characterized via admittance spectroscopy and capacitance-voltage profiling to determine the influence of the selenium ion energy on the electric parameters of the solar cells. It is shown that the impact of energetic selenium ions in the CIGS deposition process leads to a change in the activation energy and defect density and also in the spatial distribution of electrically active defects. For the interpretation of the results two defect models are taken into account.

  12. High-energy ion treatments of amorphous As40Se60 thin films for optical applications

    Directory of Open Access Journals (Sweden)

    Rashmi Chauhan

    2014-06-01

    Full Text Available The treatment of 100 MeV Ag swift-heavy ion (SHI irradiation with five different fluences (3×1010, 1×1011, 3×1011, 1×1012, and 3×1012 ions/cm2 was used to design optical and structural properties of amorphous (a- As40Se60 chalcogenide thin films. Swanepoel method was applied on transmission measurements to determine the changes in optical bandgap, Tauc parameter and linear optical parameters, i.e., linear optical absorption, extinction coefficient and linear refractive index. Dispersion of the material was determined by Wemple–DiDomenico relation. Changes in nonlinear optical parameters of third-order optical susceptibility and nonlinear refractive index were determined using semi-empirical relations. Changes in surface morphology of the films were investigated using SEM observation, which indicated that fluence 3×1012 ions/cm2 was upper threshold limit for these films for ion treatment. It is observed that optical bandgap reduces from 1.76 eV to 1.64 eV, and nonlinear refractive index increases from 1.31×10−10 [esu] to 1.74×10−10 [esu]. Linear refractive index initially increases from 2.80 to 3.52 (for fluence 3×1010 ions/cm2 and then keeps decreasing. The observed changes in optical properties upon irradiation were explained in terms of structural rearrangements by Raman measurement. The study was compiled with the previous literature to propose SHI as an effective optical engineering technique to achieve desired changes according to the need of optical/photonic applications.

  13. Effects of laser irradiation on optical properties of amorphous and annealed Ga15Se81In4 and Ga15Se79In6 chalcogenide thin films

    International Nuclear Information System (INIS)

    Al-Ghamdi, A.A.; Khan, Shamshad A.; Al-Heniti, S.; Al-Agel, F.A.; Al-Harbi, T.; Zulfequar, M.

    2010-01-01

    Amorphous thin films of Ga 15 Se 81 In 4 and Ga 15 Se 79 In 6 glassy alloys with thickness 3000 A were prepared by thermal evaporation onto chemically cleaned glass substrates. The changes in optical properties due to the influence of laser radiation on amorphous and thermally annealed thin films of Ga 15 Se 81 In 4 and Ga 15 Se 79 In 6 were calculated from absorbance and reflectance spectra as a function of photon energy in the wave length region 400-1000 nm. Analysis of the optical absorption data shows that the rule of non-direct transitions predominates. The optical band gaps observed to decrease with the increase of annealing temperatures. Furthermore, exposing thin films to laser irradiation leads to a decrease in optical band gap, absorption coefficient, refractive index and extinction coefficient for both as-prepared and annealed films. The decrease in the optical band gap is explained on the basis of change in nature of films, from amorphous to polycrystalline state, with the increase of annealing temperature and by laser irradiation for 10 min exposure time. Outcomes of our study confirm that this system may be used for photovoltaic devices.

  14. Optimization studies of HgSe thin film deposition by electrochemical atomic layer epitaxy (EC-ALE)

    CSIR Research Space (South Africa)

    Venkatasamy, V

    2006-06-01

    Full Text Available Studies of the optimization of HgSe thin film deposition using electrochemical atomic layer epitaxy (EC-ALE) are reported. Cyclic voltammetry was used to obtain approximate deposition potentials for each element. These potentials were then coupled...

  15. Review on Alkali Element Doping in Cu(In,Ga)Se2 Thin Films and Solar Cells

    DEFF Research Database (Denmark)

    Sun, Yun; Lin, Shuping; Li, Wei

    2017-01-01

    surface structure and electronic property variation induced by alkali fluoride (NaF and KF) post-deposition treatment (PDT), we discuss and interpret the following issues: ① The delamination of CIGS thin films induced by Na incorporation facilitates CuInSe2 formation and inhibits Ga during low...

  16. Refractive index extraction and thickness optimization of Cu2ZnSnSe4 thin film solar cells

    NARCIS (Netherlands)

    ElAnzeery, H.; El Daif, O.; Buffière, M.; Oueslati, S.; Ben Messaoud, K.; Agten, D.; Brammertz, G.; Guindi, R.; Kniknie, B.; Meuris, M.; Poortmans, J.

    2015-01-01

    Cu2nSnSe4 (CZTSe) thin film solar cells are promising emergent photovoltaic technologies based on low-bandgap absorber layer with high absorption coefficient. To reduce optical losses in such devices and thus improve their efficiency, numerical simulations of CZTSe solar cells optical

  17. Chemical synthesis and characterization of CdSe thin films deposited by SILAR technique for optoelectronic applications

    Directory of Open Access Journals (Sweden)

    K.B. Chaudhari

    2016-12-01

    Full Text Available CdSe thin films were deposited on the glass substrate by successive ionic layer adsorption and reaction (SILAR method. Different sets of the film are prepared by changing the number of immersion cycles as 30, 40, 50 and 60. Further the effect of a number of immersion cycles on the characteristic structural, morphological, optical and electrical properties of the films are studied. The XRD studies revealed that the deposited films showed hexagonal structure with most prominent reflection along (1 0 1 plane. Moreover, the peak intensity of (1 0 1 plane is found to be increased as the number of immersion cycles is increased. All the thin films look relatively smooth and homogeneous covering the entire surface area in FESEM image. Optical properties of the CdSe thin films for a different number of immersion cycles were studied, which indicates that the absorbance increases with the increase in the immersion cycles. Furthermore, the optical band-gap in conjunction with the electrical resistivity was found to get decreased with increase in the immersion cycles. A good correlation between the number of immersion cycles and the physical properties indicates a simple method to manipulate the CdSe material properties for optoelectronic applications.

  18. Structural, optical and electrical characterization of vacuum-evaporated nanocrystalline CdSe thin films for photosensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Vipin; Sharma, D.K.; Sharma, Kapil [Krishna Institute of Engineering and Technology, Department of Physics, Ghaziabad (India); Dwivedi, D.K. [M.M.M University of Technology, Department of Physics, Gorakhpur (India)

    2016-11-15

    II-VI nanocrystalline semiconductors offer a wide range of applications in electronics, optoelectronics and photonics. Thin films of CdSe were deposited onto ultra-clean glass substrates by vacuum evaporation method. The as-deposited films were annealed in vacuum at 350 K. The structural, elemental, morphological, optical and electrical investigations of annealed films were carried out. The X-ray diffraction pattern of the films shows that films were polycrystalline in nature having hexagonal structure with preferential orientation of grains along (002) plane. SEM image indicates that the films were uniform and well covered to the glass substrate. EDAX analysis confirms the stoichiometric composition of the film. Raman spectra were used to observe the characteristic vibrational modes of CdSe. The energy band gap of these films was obtained by absorption spectra. The films were found to have a direct type of transition of band gap occurring at 1.75 eV. The dark electrical conductivity and photoconductivity reveals that the films were semiconducting in nature indicating the suitability of these films for photosensor applications. The Hall effect measurement reveals that the films have n-type electrical conductivity. (orig.)

  19. Structural and electrical studies on nanostructured InSe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, A.A.A., E-mail: aaadarwish@gmail.com [Physics Department, Faculty of Science, University of Tabuk, Tabuk (Saudi Arabia); Physics Department, Faculty of Education at Al-Mahweet, Sana’a University, Al-Mahweet (Yemen); El-Nahass, M.M. [Physics Department, Faculty of Education, Ain Shams University, Rorxy, Cairo 11757 (Egypt); Bahlol, M.H. [Physics Department, Faculty of Education, Science and Arts at Sada’a, Amran University, Sada’a (Yemen)

    2013-07-01

    InSe powder was found to be polycrystalline with hexagonal system. X-ray diffraction and scanning electron microscopy results confirmed that the InSe films have nanostructure nature. The heat treatment enhance the crystallite size. The dark electrical conductivity of InSe films showed that the dominant conduction is through the extended states in the temperature range 293–473 K. Thermoelectric properties show a negative sign exhibiting n-type semiconductig nature of films. Current density–voltage characteristics of InSe films showed Ohmic conduction in the lower voltage range, and space charge limited conductivity (SCLC) in the relatively high-voltage range. The SCLC was controlled by an exponential distribution of traps below the conduction band. The temperature dependence of the current density allowed the calculation of some essential parameters.

  20. Deposition of CuIn(Se,S)2 thin films by sulfurization of selenized Cu/In alloys

    International Nuclear Information System (INIS)

    Sheppard, C.J.; Alberts, V.; Bekker, W.J.

    2004-01-01

    The relatively small band gap values (close to 1eV) of CuInSe 2 thin films limits the conversion efficiencies of completed CuInSe 2 /CdS/ZnO solar cell devices. In the case of traditional two-stage growth techniques, limited success has been achieved to increase the band gap by substituting indium with gallium. In this study, sputtered copper-indium alloys were exposed to a H 2 Se/Ar atmosphere under defined conditions in order to produce partially reacted CuInSe 2 structures. These films were subsequently exposed to a H 2 S/Ar atmosphere to produce monophasic CuIn(Se, S) 2 quaternary alloys. The homogeneous incorporation of S into CuInSe 2 led to a systematic shift in the lattice parameters and band gap of the ab- sorber films. From these studies optimum selenization/sulfurization conditions were determined for the deposition of homogeneous CuIn(Se,S) 2 thin films with an optimum band gap values between 1.15 and 1.2 eV. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Structural and morphological characterization of CdSe:Mn thin films

    Indian Academy of Sciences (India)

    Sarika Singh

    2017-06-24

    Jun 24, 2017 ... The films prepared by CBD are usu- ally composed of closely spaced nanocrystals [9]. The band-gap engineering of films is possible by tailoring the nanocrystellite size, which can be done by varying the deposition parameters. In the present work, we have successfully synthesized nanograins in CdSe and ...

  2. 13.7%-efficient Zn(Se,OH){sub x}/Cu(In,Ga)(S,Se){sub 2} thin-film solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Ennaoui, A. [Hahn-Meitner-Institut, Bereich Physikalische Chemie, Berlin (Germany); Blieske, U.; Lux-Steiner, M.Ch. [Hahn-Meitner-Institut, Bereich Festkoerperphysik, Berlin (Germany)

    1998-12-01

    Cu(In,Ga)Se{sub 2} (CIGS) and related semiconducting compounds have demonstrated their high potential for high-efficiency thin-film solar cells. The highest efficiency for CIGS based thin-film solar cells has been achieved with CdS buffer layers prepared by a solution growth method known as chemical based deposition (CBD). With the aim of developing Cd-free chalcopyrite-based thin-film solar cells, Zn(Se,OH){sub x} buffer layers were deposited by CBD on polycrystalline Cu(In,Ga)(S,Se){sub 2} (CIGSS). A total-area conversion efficiency of 13.7% was certified by the Fraunhofer Institute for Solar Energy Systems. The CIGSS absorber was fabricated by Siemens Solar Industries (California). For device optimisation, the thickness and good surface coverage were controlled by XPS-UPS photoemission spectroscopy. A Zn(Se,OH){sub x} thickness below 7 nm has been found to be optimum for achieving a homogeneous and compact buffer film on CIGSS, with open-circuit photovoltage V{sub oc} = 535 mV, fill factor FF = 70.76% and a high short-circuit photocurrent density J{sub sc} 36.1 mA cm{sup -2}. (Author)

  3. The structural and material properties of Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ya-Fen; Hsu, Hung-Pin [Department of Electronic Engineering, Ming Chi University of Technology, 84 Gongzhuan Rd., New Taipei City 243 (China); Wang, Jen-Cheng; Chen, Hui-Ying [Department of Electronic Engineering, Chang Gung University, 259 Wenhwa 1st Rd., Taoyuan 333 (China)

    2012-06-15

    We report on the structural and material properties of Cu-poor CuIn{sub 1-x}Ga{sub x} Se{sub 2} (CIGS) thin films with different gallium contents grown using the co-evaporation technique. Temperature-dependent photoluminescence (PL) and high-resolution X-ray diffraction measurements were performed. The PL emission peaks observed around 1.0-1.2 eV are attributed to donor-acceptor pair luminescence. These donor-acceptor pair emissions are considered to originate from relatively shallow acceptor and donor energy levels. In addition, the X-ray diffraction spectra of the samples are simulated using a theoretical model. From the analysis, it is found that the sample with higher gallium content exhibits smaller grain size and the microstructure size uniformity is reduced. The theoretical calculation result is consistent with the experimental results derived from the PL spectra. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Preparation of SnSe thin films by encapsulated selenization; Saput tipis SnSe disediakan dengan kaedah penselenidan tertudung-tebat

    Energy Technology Data Exchange (ETDEWEB)

    Sabar, D Hutagalung [Universitas Sumatera Utara, Medan (Indonesia). Dept. of Physics; Sakrani, Samsudi; Wahab, Yussof [Universiti Teknologi Malaysia, Skudai, Johor Bahru (Malaysia). Dept. of Physics

    1994-12-31

    Tin selenide thin films were prepared by encapsulated selenization. A stacked layer of evaporated Sn and Se films were annealed in a carbon block at temperatures 100 - 500 degree Celsius for 3 hours. X-ray analysis and SEM (Scanning electron) micrograph results showed that SnSe was initially formed at 150 degree Celsius with crystal size 30.0 nm and reached optimum formation at 200 daximum of 57.4 % yield of 5-decene. Other factors such as reaction temperatures, types of solvent and wt% of rhenium loadings influence the activity of the catalytic system.

  5. High-temperature fabrication of Ag(In,Ga)Se{sub 2} thin films for applications in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xianfeng [International Center for Science and Engineering Programs, Waseda University, Tokyo (Japan); Yamada, Akira [Department of Physical Electronics, Tokyo Institute of Technology, Tokyo (Japan); Kobayashi, Masakazu [Department of Electrical Engineering and Bioscience, Waseda University, Tokyo (Japan); Kagami Memorial Research Institute for Materials Science, Waseda University, Tokyo (Japan)

    2017-10-15

    Molecular beam epitaxy was used to fabricate Ag(In,Ga)Se{sub 2} (AIGS) thin films. To improve the diffusion of Ag, high-temperature deposition and high-temperature annealing methods were applied to fabricate AIGS films. The as-grown AIGS thin films were then used to make AIGS solar cells. We found that grain size and crystallinity of AIGS films were considerably improved by increasing the deposition and annealing temperature. For high-temperature deposition, temperatures over 600 C led to decomposition of the AIGS film, desorption of In, and deterioration of its crystallinity. The most appropriate deposition temperature was 590 C and a solar cell with a power conversion efficiency of 4.1% was obtained. High-temperature annealing of the AIGS thin films showed improved crystallinity as annealing temperature was increased and film decomposition and In desorption were prevented. A solar cell based on this film showed the highest conversion efficiency of 6.4% when annealed at 600 C. When the annealing temperature was further increased to 610 C, the performance of the cell deteriorated due to loss of the out-of-plane Ga gradient. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Optical and structural properties of FeSe2 thin films obtained by selenization of sprayed amorphous iron oxide films

    International Nuclear Information System (INIS)

    Ouertani, B.; Ouerfelli, J.; Saadoun, M.; Zribi, M.; Rabha, M.Ben; Bessais, B.; Ezzaouia, H.

    2006-01-01

    We report in this work the optical and structural properties of iron diselenide films (FeSe 2 ) obtained by selenization under vacuum of amorphous iron oxide films predeposited by spray pyrolysis. The structure of the FeSe 2 films was investigated by scanning electron microscopy (SEM), microprobe analyses, atomic force microscopy (AFM) and X-ray diffraction (XRD). XRD and micro-probe analyses showed that FeSe 2 as well as FeSe 2-x phases begin to appear at a selenization temperature of 500 deg. C. As the selenization temperature rises, the iron diselenide films become more stoichiometric with a dominance of the FeSe 2 phase. At 550 deg. C, a single FeSe 2 phase having good crystallinity was obtained. At 600 deg. C, two phases were detected: the major one corresponds to Fe 3 O 4 , and the minor one to FeSe 2 . SEM surface views show that FeSe 2 films have granular structure with small spherical crystallites. However, layered and clustered FeSe 2 films were found, respectively, at 550 deg. C and 600 deg. C. Absorption measurements show that iron diselenide films have a direct and an indirect gaps of about 1.03 eV and 0.3 eV, which were suggested to be due to the stoichiometric FeSe 2 phase and to a Fe-rich non-stoichiometric phase, respectively

  7. The effect of Na on Cu-K-In-Se thin film growth

    Science.gov (United States)

    Muzzillo, Christopher P.; Tong, Ho Ming; Anderson, Timothy J.

    2018-04-01

    Co-evaporation of Cu-KF-In-Se was performed on substrates with varied Na supply. Compositions of interest for photovoltaic absorbers were studied, with ratios of (K + Cu)/In ∼ 0.85 and K/(K + Cu) ∼ 0-0.57. Bare soda-lime glass (SLG) substrates had the highest Na supply as measured by secondary ion mass spectrometry, while SLG/Mo and SLG/SiO2/Mo substrates led to 3x and 3000x less Na in the growing film, respectively. Increased Na supply favored Cu1-xKxInSe2 (CKIS) alloy formation as proven by X-ray diffraction (XRD), while decreased Na supply favored the formation of CuInSe2 + KInSe2 mixed-phase films. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed the KInSe2 precipitates to be readily recognizable planar crystals. Extrinsic KF addition during film growth promoted diffusion of Na out from the various substrates and into the growing film, in agreement with previous reports. Time-resolved photoluminescence showed enhanced minority carrier lifetimes for films with moderate K compositions (0.04 interdependency can be used to engineer alkali metal bonding in Cu(In,Ga)(Se,S)2 absorbers to optimize both initial and long-term photovoltaic power generation.

  8. Growth of polycrystalline Cu(In,Ga)Se2 thin films using a radio frequency-cracked Se-radical beam source and application for photovoltaic devices

    International Nuclear Information System (INIS)

    Ishizuka, Shogo; Shibata, Hajime; Yamada, Akimasa; Fons, Paul; Sakurai, Keiichiro; Matsubara, Koji; Niki, Shigeru

    2007-01-01

    Cu(In,Ga)Se 2 (CIGS) thin films were grown using a rf-cracked Se-radical beam source. A unique combination of film properties, a highly dense and smooth surface with large grain size, is shown. These features seem to have no significant influence on the photovoltaic performance. Defect control in bulk CIGS leading to corresponding variations in the electrical and photoluminescence properties was found to be possible by regulating the Se-radical source parameters. A competitive energy conversion efficiency of 17.5%, comparable to that of a Se-evaporative source grown CIGS device, has been demonstrated from a solar cell fabricated using a Se-radical source grown CIGS absorber

  9. Study of structural and optical properties of Cd{sub 1-x}Zn{sub x}Se thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wahab, L.A., E-mail: aly_lo2003@yahoo.com [National Center for Radiation Research and Technology, Nasr City, Cairo (Egypt); Zayed, H.A. [University Collage of Women for Art, Science and Education, Ain Shams University, Cairo (Egypt); El-Galil, A.A. Abd [National Center for Radiation Research and Technology, Nasr City, Cairo (Egypt)

    2012-06-01

    Cd{sub 1-x}Zn{sub x}Se (x = 0, 0.5 and 1) thin films have been deposited onto glass substrates using thermal evaporation technique. The lattice constants, grain size, microstrain and dislocation density were studied by using X-ray diffraction. In addition the optical constants were calculated in the wavelength range 400-2500 nm. Transmittance and reflectance were used to calculate the absorption coefficient {alpha} and the optical band gap E{sub g}. The linear relation of ({alpha}h{upsilon}){sup 2} as a function of photon energy h{upsilon} for the thin films illustrated that the films exhibit a direct band gap, which increases with increasing Zn content. This increasing of optical band gap was interpreted in accordance to the increasing in the cohesive energy. Optical constants, such as refractive index n, optical conductivity {sigma}{sub opt}, complex dielectric constant, relaxation time {tau} and dissipation factor tan{delta} were determined. The optical dispersion parameters E{sub 0}, E{sub d} were determined according to Wemple and Di Domenico method. - Highlights: Black-Right-Pointing-Pointer ZnSe thin film has cubic zinc blende structure while CdSe and Cd{sub 0.5}Zn{sub 0.5}Se thin films have hexagonal structure. Black-Right-Pointing-Pointer Grain size of Cd{sub 1-x}Zn{sub x}Se decreases with increasing x (x = 0, 0.5 and 1). Black-Right-Pointing-Pointer Optical band gap increases with increasing x.

  10. Phase transformation during simultaneous chalcogenization of CuIn(S,Se){sub 2} thin films using metalorganic sources

    Energy Technology Data Exchange (ETDEWEB)

    Shoji, Ryuki; Kayama, Yoshiki; Sugiyama, Mutsumi [Department of Electrical Engineering, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510 (Japan); Chichibu, Shigefusa F. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577 (Japan)

    2017-06-15

    Simultaneous chalcogenization of CuIn(S{sub y},Se{sub 1-y}){sub 2} (CISSe) thin films has been demonstrated using organometallic sources such as diethylselenide [(C{sub 2}H{sub 5}){sub 2}Se] and ditertiarybutylsulfide [(t-C{sub 4}H{sub 9}){sub 2}S] to obtain homogeneous CISSe pseudobinary alloys with controlled amounts of Se and S species. Low-temperature chalcogenization at 300 C resulted in the formation of Cu-SSe and In-SSe alloys diffused into the Cu{sub 11}In{sub 9} metallic precursor. On the other hand, high-temperature chalcogenization produced CISSe thin films without additional phases. The obtained results can be used for elucidating the mechanism of simultaneous chalcogenization and development of high-performance and cost-effective commercial applications. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Study of optical properties of vacuum evaporated carbon nanotube containing Se80Te16Cu4 thin films

    Science.gov (United States)

    Upadhyay, A. N.; Tiwari, R. S.; Singh, Kedar

    2016-08-01

    Thin films of Se80Te16Cu4 glassy alloy and 3 wt.% of carbon nanotubes (CNTs) containing Se80Te16Cu4 glassy composite were deposited on clean glass substrate by thermal evaporation technique. The scanning electron microscope and energy dispersive x-ray analysis were performed to investigate the surface morphology and elemental composition of as synthesised samples. The reflectance and transmittance spectra of as-deposited thin films were recorded (200-1100 nm) by using UV/VIS/NIR spectrophotometer. The optical band gap and optical constants such as absorption coefficient (α), refractive index (n) and extinction coefficient (k) of Se80Te16Cu4 and 3 wt.% CNTs-Se80Te16Cu4 glassy composite thin films were calculated. It is observed that optical properties alter due to CNTs incorporation in Se80Te16Cu4 glassy alloy. Effect on optical properties due to CNTs incorporation can be explained in terms of concentration of unsaturated bonds/defects in the localised states.

  12. Optical properties of CuSe thin films - band gap determination

    Directory of Open Access Journals (Sweden)

    Petrović Milica

    2017-01-01

    Full Text Available Copper selenide thin films of three different thicknesses have been prepared by vacuum evaporation method on a glass substrate at room temperature. The optical properties of the films were investigated by UV-VIS-NIR spectroscopy and photoluminescence spectroscopy. Surface morphology was investigated by field-emission scanning electron microscopy. Copper selenide exhibits both direct and indirect transitions. The band gap for direct transition is found to be ~2.7 eV and that for indirect transition it is ~1.70 eV. Photoluminescence spectra of copper selenide thin films have also been analyzed, which show emission peaks at 530, 550, and 760 nm. The latter corresponds to indirect transition in investigated material. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45003

  13. Acoustic phonon dynamics in thin-films of the topological insulator Bi2Se3

    International Nuclear Information System (INIS)

    Glinka, Yuri D.; Babakiray, Sercan; Johnson, Trent A.; Holcomb, Mikel B.; Lederman, David

    2015-01-01

    Transient reflectivity traces measured for nanometer-sized films (6–40 nm) of the topological insulator Bi 2 Se 3 revealed GHz-range oscillations driven within the relaxation of hot carriers photoexcited with ultrashort (∼100 fs) laser pulses of 1.51 eV photon energy. These oscillations have been suggested to result from acoustic phonon dynamics, including coherent longitudinal acoustic phonons in the form of standing acoustic waves. An increase of oscillation frequency from ∼35 to ∼70 GHz with decreasing film thickness from 40 to 15 nm was attributed to the interplay between two different regimes employing traveling-acoustic-waves for films thicker than 40 nm and the film bulk acoustic wave resonator (FBAWR) modes for films thinner than 40 nm. The amplitude of oscillations decays rapidly for films below 15 nm thick when the indirect intersurface coupling in Bi 2 Se 3 films switches the FBAWR regime to that of the Lamb wave excitation. The frequency range of coherent longitudinal acoustic phonons is in good agreement with elastic properties of Bi 2 Se 3

  14. Electrodeposition and characterization of CdSe{sub x}Te{sub 1-x} semiconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Benamar, E.; Rami, M.; Fahoume, M.; Chraibi, F.; Ennaoui, A. [Faculty of Sciences, Laboratory of Materials Physics, Dept. of Physics, Rabat (Morocco)

    1999-07-01

    Thin polycrystalline films of cadmium chalcogenides CdSe{sub x}Te{sub 1-x} (0{<=}x{<=}1) can be used for various technical applications in particular for the conversion of solar energy in photoelectrochemical devices. They have been prepared by electrochemical plating on ITO (indium tin oxide) coated glass substrates from an acid sulfate solution at 90 deg. C. Structural, morphological and compositional studies of the deposited films are reported as a function of the x coefficient. XRD analysis shows that all deposits have a cubic structure with a preferred orientation along the (111) direction. The composition in the films is found to vary linearly with the composition in the solution. The increase in the selenium content x in the CdSe{sub x}Te{sub 1-x} films decreases the lattice constant and increases the band gap. Nevertheless this latter presents a minimum for x = 0.27.

  15. In-situ XRD study of alloyed Cu2ZnSnSe4-CuInSe2 thin films for solar cells

    International Nuclear Information System (INIS)

    Hartnauer, Stefan; Wägele, Leonard A.; Jarzembowski, Enrico; Scheer, Roland

    2015-01-01

    We investigate the growth of Cu 2 ZnSnSe 4 -CuInSe 2 (CZTISe) thin films using a 2-stage (Cu-rich/Cu-free) co-evaporation process under simultaneous application of in-situ angle dispersive X-ray diffraction (XRD). In-situ XRD allows monitoring the phase formation during preparation. A variation of the content of indium in CZTISe leads to a change in the lattice constant. Single phase CZTISe is formed in a wide range, while at high In contents a phase separation is detected. Because of different thermal expansion coefficients, the X-ray diffraction peaks of ZnSe and CZTISe can be distinguished at elevated substrate temperatures. The formation of ZnSe appears to be inhibited even for low indium content. In-situ XRD shows no detectable sign for the formation of ZnSe. First solar cells of CZTISe have been prepared and show comparable performance to CZTSe. - Highlights: • In-situ XRD study of two-stage co-evaporated Cu 2 ZnSnSe 4 -CuInSe 2 alloyed thin films. • No detection of ZnSe with in-situ XRD due to Indium incorporation • Comparable efficiency of alloyed solar cells

  16. Synthesis, structure and magnetic properties of crystallographically aligned CuCr{sub 2}Se{sub 4} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Esters, Marco [Department of Chemistry, University of Oregon, Eugene, OR 97403 (United States); Liebig, Andreas [Institut für Physik, Universität Augsburg, 86159 Augsburg (Germany); Ditto, Jeffrey J.; Falmbigl, Matthias [Department of Chemistry, University of Oregon, Eugene, OR 97403 (United States); Albrecht, Manfred [Institut für Physik, Universität Augsburg, 86159 Augsburg (Germany); Johnson, David C., E-mail: davej@uoregon.edu [Department of Chemistry, University of Oregon, Eugene, OR 97403 (United States)

    2016-06-25

    We report the low temperature synthesis of highly textured CuCr{sub 2}Se{sub 4} thin films using the modulated elemental reactant (MER) method. The structure of CuCr{sub 2}Se{sub 4} is determined for the first time in its thin film form and exhibits cell parameters that are smaller than found in bulk CuCr{sub 2}Se{sub 4}. X-ray diffraction and precession electron diffraction show a strong degree of crystallographic alignment of the crystallites, where the <111> axis is oriented perpendicular to the substrate surface, while being rotationally disordered within the plane. Temperature and field dependent in-plane and out-of-plane magnetization measurements show that the film is ferromagnetic with a Curie temperature of 406 K CuCr{sub 2}Se{sub 4} synthesized utilizing the MER method shows stronger magnetic anisotropy (effective anisotropy: 1.82 × 10{sup 6} erg cm{sup −3}; shape anisotropy: 1.07 × 10{sup 6} erg cm{sup −3}), with the easy axis lying out of plane, and a larger magnetic moment (6 μ{sub B}/f.u.) than bulk CuCr{sub 2}Se{sub 4}. - Highlights: • Crystallographically aligned, phase pure CuCr{sub 2}Se{sub 4} were synthesized. • The degree of alignment decreases with annealing time. • The films are ferromagnetic with the easy axis along the <111> direction. • The magnetization is larger than bulk CuCr{sub 2}Se{sub 4} or other CuCr{sub 2}Se{sub 4} films made to date.

  17. Structural and optical properties of electrodeposited culnSe{sub 2} thin films for photovoltaic solar cells; Propiedades estructurales y opticas de laminas delgadas de CulnSe2 electrodepositadas para su aplicacion en celulas solares fotovoltaicas

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, C; Herrero, J; Galiano, F

    1990-07-01

    Optical an structural properties of electrodeposited copper indium diselenide, CulnSe2, thin films were studied for its application in photovoltaic devices. X-ray diffraction patterns showed that thin films were grown in chalcopyrite phase after suitable treatments. Values of Eg for the CulnSe2 thin films showed a dependence on the deposition potential as determined by optical measurements. (Author) 47 refs.

  18. Investigation of Au9+ swift heavy ion irradiation on CdS/CuInSe2 thin films

    International Nuclear Information System (INIS)

    Joshi, Rajesh A.; Taur, Vidya S.; Singh, Fouran; Sharma, Ramphal

    2013-01-01

    In the present manuscript we report about the preparation of CdS/CuInSe 2 heterojunction thin films by chemical ion exchange method and investigation of 120 MeV Au 9+ swift heavy ions (SHI) irradiation effect on its physicochemical as well as optoelectronic properties. These pristine (as grown) samples are irradiated with 120 MeV Au 9+ SHI of 5×10 11 and 5×10 12 ions/cm 2 fluencies and later on characterized for structural, compositional, morphological, optical and I–V characteristics. X-ray diffraction (XRD) pattern obtained from pristine and irradiated films shows considerable modifications in peak intensity as well as rising of some new peaks, corresponding to In 2 Se 3 , Cu 3 Se 2 and CuIn 2 Se 3 materials. Transmission electron microscope (TEM) images show decrease in grain size upon increase in irradiation ion fluencies, which is also supported from the observation of random and uneven distribution of nano-grains as confirmed through scanning electron microscope (SEM) images. Presence of Cd, Cu, In, S and Se in energy dispersive X-ray spectrum analysis (EDAX) confirms the expected and observed elemental composition in thin films, the absorbance peaks are related to band to band transitions and spin orbit splitting while energy band gap is observed to increase from 1.36 for pristine to 1.53 eV for SHI irradiated thin films and I–V characteristics under illumination to 100 mW/cm 2 light source shows enhancement in conversion efficiency from 0.26 to 1.59% upon irradiation. - Highlights: • Nanostructured CdS/CuInSe 2 can be grown by chemical ion exchange method. • Physicochemical and optoelectronic properties can be modified by 120 MeV Au 9+ SHI Irradiation. • Solar energy conversion efficiency improved from 0.26 to 1.59% in CdS/CuInSe 2 upon irradiation

  19. Characterization of in-situ annealed sub-micron thick Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ko, Byoung-Soo; Sung, Shi-Joon; Hwang, Dae-Kue, E-mail: dkhwang@dgist.ac.kr

    2015-09-01

    Sub-micron thick Cu(In,Ga)Se{sub 2} (CIGS) thin films were deposited on Mo-coated soda-lime glass substrates under various conditions by single-stage co-evaporation. Generally, the short circuit current (J{sub sc}) decreased with the decreasing thickness of the absorber layer. However, in this study, J{sub sc} was nearly unchanged with decreasing thickness, while the open circuit voltage (V{sub oc}) and fill factor (FF) decreased by 31.9 and 31.1%, respectively. We believe that the remarkable change of V{sub oc} and FF can be attributed to the difference in the total amount of injected thermal energy. Using scanning electron microscopy, we confirmed that the surface morphology becomes smooth and the grain size increased after the annealing process. In the X-ray diffraction patterns, the CIGS thin film also showed an improved crystal quality. We observed that the electric properties were improved by the in-situ annealing of CIGS thin films. The reverse saturation current density of the annealed CIGS solar cell was 100 times smaller than that of reference solar cell. Thus, sub-micron CIGS thin films annealed under a constant Se rate showed a 64.7% improvement in efficiency. - Highlights: • The effects of in-situ annealing the sub-micron CIGS film have been investigated. • The surface morphology and the grain size were improved by in-situ annealing. • The V{sub oc} and FF of the films were increased by about 30% after in-situ annealing. • In-situ annealing of sub-micron thick CIGS films can be improved an efficiency.

  20. Buried homojunction in CdS/Sb2Se3 thin film photovoltaics generated by interfacial diffusion

    Science.gov (United States)

    Zhou, Ying; Li, Yang; Luo, Jiajun; Li, Dengbing; Liu, Xinsheng; Chen, Chao; Song, Huaibing; Ma, Jingyuan; Xue, Ding-Jiang; Yang, Bo; Tang, Jiang

    2017-07-01

    Antimony selenide (Sb2Se3) emerges as a very promising non-toxic absorber material for thin film photovoltaics, and most of the devices, either in the superstrate or substrate configuration, employed CdS as the buffer layer. Due to the peculiar one-dimensional crystal structure of Sb2Se3, severe interfacial diffusion would be expected. In this letter, the interfacial diffusion in CdS/Sb2Se3 photovoltaics was carefully characterized from a combined material and device physics characterization. The results indicated that a buried homojunction located deep inside the Sb2Se3 absorber layer due to Cd diffusion, instead of the apparent CdS/Sb2Se3 heterojunction, dictated charge separation and device performance in Sb2Se3 thin film solar cells. Cd diffusion converted p-type Sb2Se3 into n-type by introducing a donor level with an activation energy of 0.22 eV. Our studies deepen the understanding of Sb2Se3 photovoltaics and shed light on their further performance optimization.

  1. Growth Structural and Optical Properties of the Thermally Evaporated Tin Diselenide (SnSe2) Thin Films

    OpenAIRE

    R. Sachdeva1,; M. Sharma1,; A. Devi1,; U. Parihar1,; N. Kumar1,; N. Padha1,; C.J. Panchal

    2011-01-01

    Tin diselenide (SnSe2) compound was prepared by melt-quenching technique from its constituent elements. The phase structure and composition of the chemical constituents present in the bulk has been determined using X-ray diffraction (XRD) and energy dispersion X-ray analysis (EDAX) respectively. SnSe2 thin films were grown using direct thermal evaporation of SnSe2 compound material on chemically cleaned glass substrate, which were held at different substrate temperatures. X-ray diffraction an...

  2. Advances in Cost-Efficient Thin-Film Photovoltaics Based on Cu(In,Ga)Se2

    OpenAIRE

    Michael Powalla; Stefan Paetel; Dimitrios Hariskos; Roland Wuerz; Friedrich Kessler; Peter Lechner; Wiltraud Wischmann; Theresa Magorian Friedlmeier

    2017-01-01

    In this article, we discuss the leading thin-film photovoltaic (PV) technology based on the Cu(In,Ga)Se2 (CIGS) compound semiconductor. This contribution includes a general comparison with the conventional Si-wafer-based PV technology and discusses the basics of the CIGS technology as well as advances in world-record-level conversion efficiency, production, applications, stability, and future developments with respect to a flexible product. Once in large-scale mass production, the CIGS techno...

  3. Characterization of high quality Cu(In,Ga)Se{sub 2} thin films prepared by rf-magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Bouchama, Idris [Departement d' Electronique, Faculte de Technologie, Universite de Msila (Algeria); Djessas, Kamal [Laboratoire Procedes Materiaux et Energie Solaire, PROMES-CNRS, Rambla de la Thermodynamique, Technosud, 66100 Perpignan (France); Bouloufa, Abdeslam [Laboratoire d' Electrochimie et Materiaux, Universite Ferhat Abbas de Setif (Algeria); Gauffier, Jean-Luc [Departement de Physique, INSA de Toulouse, 135, Avenue de Rangueil, 31077 Toulouse Cedex 4 (France)

    2013-01-15

    This paper reports the production of high quality polycrystalline thin layers of CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} (CIGS), using rf-magnetron sputtering, from a powder target. These films are designed to be used as absorbers in solar cells. The depositions were carried out at substrate temperatures below 250 C and glass substrates was used. The influence of the substrate temperatures on the crystalline quality as well as structural, optical and electrical properties of thin layers obtained has been studied. X-ray diffraction showed that the films were highly orientated in the (112) and/or (204)/(220) direction. In{sub 2}Se{sub 3} secondary phase was observed on the samples grown at lower substrate temperatures. The surface morphology of CIGS layers studied by Atomic Force Microscopy (AFM) and Scanning Electronic Microscopy (SEM) has been also discussed. The most surprising and exciting outcome of this study was that the as grown films were of near stoichiometric composition. Resistivity measurements were carried out using the four point probe method. The optical absorption showed that energy gap values are between 1.13 and 1.18 eV and rather sharp absorption fronts. Thin film resistivities are between 10.7 and 60.9 {Omega}.cm depending on the experimental growth conditions (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Syntheses and characterization of thin films of Te94Se6 nanoparticles for semiconducting and optical devices

    International Nuclear Information System (INIS)

    Salah, Numan; Habib, Sami S.; Memic, Adnan; Alharbi, Najlaa D.; Babkair, Saeed S.; Khan, Zishan H.

    2013-01-01

    Thin films of Te 94 Se 6 nanoparticles were synthesized using the physical vapor condensation technique at different argon (Ar) pressures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy, absorption spectrum, photoluminescence (PL) and Raman spectroscopy. XRD results show that the as-grown films have a polycrystalline structure. SEM images display uniform nanoparticles in these films where the size increases from ∼ 12 to about 60 nm by decreasing Ar pressure from 667 to 267 Pa. These as-grown thin films were found to have direct band gaps, whose value decreases with increasing particle size. The absorption and extinction coefficients for these films were also investigated. PL emission spectra exhibit three bands peaking at 666, 718 and 760 nm, while Raman spectra displayed three bands located at 123, 143 and 169 cm −1 . No significant changes are observed in positions or intensities of these bands by decreasing the Ar pressure, except that of the last band of PL; where the intensity increases. The obtained results on this Te 94 Se 6 nanomaterial especially its controlled direct bandgap might be useful for development of optical disks and other semiconducting devices. - Highlights: ► Thin films of Te 94 Se 6 nanoparticles were grown at different argon (Ar) pressures. ► Size of the nanoparticles increased by decreasing Ar pressure. ► They have direct band gap, whose value decreases by increasing the particle size. ► These nanomaterials might be useful for development of semiconducting devices

  5. Colloidal Precursors from 'Ball-Milling in Liquid Medium' Process for CuInSe{sub 2} Thin Film

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jae Hoon; Kim, Seung Joo [Ajou University, Suwon (Korea, Republic of)

    2010-09-15

    CIS thin film can be fabricated by using the precursor obtained through ball-milling the elemental reagents in liquid media. The amorphous colloidal precursor with good dispersity was prepared in the medium that contains strong base and polar solvent (2 M ethylenediamine in DMF solution as used in this study). The 'ball-milling in liquid medium' method requires only elemental sources as starting materials and a proper solution so that it can be employed without additional processes for separation and purification. As a simple and less-toxic preparative route, this method would be practically available to prepare CIS-related solar cells. CuInSe{sub 2} (CIS) and related chalcopyrite compounds are very promising materials for thin film solar cells due to their favorable band gap, high optical absorption coefficient and long-term stability. CIS-based solar cells have shown the highest conversion efficiency reaching a value of 20%. However, the vacuum-based processes that are used to fabricate CIS thin-films have some drawbacks such as the complexity in process, high production cost and difficulty in scaling up. Recently, several research groups have proposed different non-vacuum deposition processes for CIS solar cell. For example, H. W. Hillhouse et al. prepared the CIS absorber layer by using 'nanocrystal ink method' in which a colloidal nanocrystal ink was obtained from reaction of CuCl, InCl{sub 3} and Se in oleylamine. D. B. Mitzi et al. used a solution-based precursor that was prepared by dissolution of Cu{sub 2}Se, In{sub 2}Se{sub 3}, Ga{sub 2}Se{sub 3} and Se in hydrazine to fabricate the Ga-containing absorber layer, Cu(In,Ga)Se{sub 2}.

  6. Nature of Dielectric Properties, Electric Modulus and AC Electrical Conductivity of Nanocrystalline ZnIn2Se4 Thin Films

    Science.gov (United States)

    El-Nahass, M. M.; Attia, A. A.; Ali, H. A. M.; Salem, G. F.; Ismail, M. I.

    2018-02-01

    The structural characteristics of thermally deposited ZnIn2Se4 thin films were indexed utilizing x-ray diffraction as well as scanning electron microscopy techniques. Dielectric properties, electric modulus and AC electrical conductivity of ZnIn2Se4 thin films were examined in the frequency range from 42 Hz to 106 Hz. The capacitance, conductance and impedance were measured at different temperatures. The dielectric constant and dielectric loss decrease with an increase in frequency. The maximum barrier height was determined from the analysis of the dielectric loss depending on the Giuntini model. The real part of the electric modulus revealed a constant maximum value at higher frequencies and the imaginary part of the electric modulus was characterized by the appearance of dielectric relaxation peaks. The AC electrical conductivity obeyed the Jonscher universal power law. Correlated barrier hopping model was the appropriate mechanism for AC conduction in ZnIn2Se4 thin films. Estimation of the density of states at the Fermi level and activation energy, for AC conduction, was carried out based on the temperature dependence of AC electrical conductivity.

  7. Structural and optical analysis of 60Co gamma-irradiated thin films of polycrystalline Ga10Se85Sn5

    Science.gov (United States)

    Ahmad, Shabir; Asokan, K.; Shahid Khan, Mohd.; Zulfequar, M.

    2015-12-01

    The present study focuses on the effects of gamma irradiation on structural and optical properties of polycrystalline Ga10Se85Sn5 thin films with a thickness of ∼300 nm deposited by the thermal evaporation technique on cleaned glass substrates. X-ray diffraction patterns of the investigated thin films show that crystallite growth occurs in the orthorhombic phase structure. The surface study carried out by using the scanning electron microscope (SEM) confirms that the grain size increases with gamma irradiation. The optical parameters were estimated from optical transmission spectra data measured from a UV-vis-spectrophotometer in the wavelength range of 200-1100 nm. The refractive index dispersion data of the investigated thin films follow the single oscillator model. The estimated values of static refractive index n0, oscillator strength Ed, zero frequency dielectric constant ε0, optical conductivity σoptical and the dissipation factor increases after irradiation, while the single oscillator energy Eo decreases after irradiation. It was found that the value of the optical band gap of the investigated thin films decreases and the corresponding absorption coefficient increases continuously with an increase in the dose of gamma irradiation. This post irradiation changes in the values of optical band gap and absorption coefficient were interpreted in terms of the bond distribution model.

  8. Electron-gun Evaporation of Cu and In thin Films as Precursors for CuInSe, Formation

    International Nuclear Information System (INIS)

    Caballero, R.; Guillen, C.

    2001-01-01

    In the present invigorations CuInSe, is obtained in two stages: sequential evaporation of Cu and In using an electron gun evaporator on substrates up to 30 x 30 cm 2 , and a posterior selenization of the deposited films. The study is mainly focused on the first stage, in where the control of the different evaporation parameters of the metal precursors is essential. Electrical measurements are carried out, and also the topography and the thickness are determined with the object of studying the properties and homogeneity of the thin films. (Author) 19 refs

  9. Fabrication of dye sensitized solar cell using Cr doped Cu-Zn-Se type chalcopyrite thin film

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, D. Paul; Venkateswaran, C. [Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai-600 025 (India); Ganesan, S.; Suthanthiraraj, S. Austin; Maruthamuthu, P. [Department of Energy, University of Madras, Guindy Campus, Chennai 600 025 (India); Kovendhan, M. [Department of Physics, Presidency College, Chennai 600 005 (India)

    2011-09-15

    Chalcopyrites are a versatile class of semiconductors known for their potential in photovoltaic applications. Considering the well established CuInSe{sub 2} as a prototype system, a new compound of the chalcopyrite type, Cu{sub 1-x}Zn{sub 1-y}Se{sub 2-{delta}}, by replacing In with Zn, has been prepared (both undoped and 2% Cr doped) by the metallurgical method. Thin films have been deposited by the thermal evaporation technique using the stabilized polycrystalline compounds as charge. Structural, compositional, morphological, and optical properties of the films are analyzed and reported. Use of these films as electrodes in dye sensitized solar cell (DSSC) is demonstrated. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Influence of citrate ions as complexing agent for electrodeposition of CuInSe{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chraibi, F. [Universite Libre de Bruxelles (Belgium). Service de Sciences des Materiaux et Electrochimie; Universite Mohammed 5, Rabat (Morocco). Dept. de Physique; Fahoume, M.; Ennaoui, A. [Universite Mohammed 5, Rabat (Morocco). Dept. de Physique; Delplancke, J.L. [Universite Libre de Bruxelles (Belgium). Service de Sciences des Materiaux et Electrochimie

    2001-08-16

    The preparation of CuInSe{sub 2} thin films by electrodeposition is studied. The effect of sodium citrate (Na{sub 3}C{sub 6}H{sub 5}O{sub 7}) as complexing agent on the electrodeposition of pure copper, indium, selenium and of their ternary alloy is emphasized. Cathodic shifts of the copper and selenium electrodeposition potentials with increasing citrate concentration are observed. On the contrary, the presence of citrate in the electrolyte does not change the indium electrodeposition potential but improves its crystallinity. The surface morphology and the composition of the deposited films are characterized by scanning electron microscopy (SEM). The texture of the deposits and their compositions are analyzed by X-ray diffraction. The formation of CuInSe{sub 2} films with a chalcopyrite structure and good stoichiometry is observed. (orig.)

  11. Effects of gamma-ray irradiation on the optical properties of amorphous Se100-xHgx thin films

    Science.gov (United States)

    Ahmad, Shabir; Islam, Shama; Nasir, Mohd.; Asokan, K.; Zulfequar, M.

    2018-06-01

    In this study, the thermal quenching technique was employed to prepare bulk samples of Se100-xHgx (x = 0, 5, 10, 15). Thin films with a thickness of ∼250 nm were deposited on glass substrates using the thermal evaporation technique. These films were irradiated with gamma rays at doses of 25-100 kGy. The elemental compositions of the as-deposited thin films were confirmed by energy dispersive X-ray analysis and Rutherford backscattering spectrometry. X-ray diffraction analysis confirmed the crystalline nature of these thin films upto the dose of 75 kGy. Fourier transform-infrared spectroscopy showed that the concentration of defects decreased after gamma irradiation. Microstructural analysis by field emission scanning electron microscopy indicated that the grain size increases after irradiation. Optical study based on spectrophotometry showed that the optical band gap values of these films increase after the addition of Hg whereas they decrease after gamma irradiation. We found that the absorption coefficient increases with doses up to 75 kGy but decreases at higher doses. These remarkable shifts in the optical band gap and absorption coefficient values are interpreted in terms of the creation and annihilation of defects, which are the main effects produced by gamma irradiation.

  12. Microstructure and optical studies of electron beam evaporated ZnSe1−xTex nanocrystalline thin films

    International Nuclear Information System (INIS)

    Emam-Ismail, M.; El-Hagary, M.; Shaaban, E.R.; Al-Hedeib, A.M.

    2012-01-01

    Highlights: ► The structural and optical properties of ZnSeTe thin films were studied. ► The micro structural parameters of the films have been determined. ► The room temperature reflectance and transmittance data are analyzed. ► The refractive index and energy gap are determined. ► The single oscillator parameters were calculated. - Abstract: Nanocrystalline thin films of ZnSe 1−x Te x (0.0 ≤ x ≤ 1.0) were deposited on glass substrate using electron beam deposition technique. The structure of the prepared films was examined using X-ray diffraction technique and revealed that the deposited films have polycrystalline zinc blend structure with lattice constant, a, increasing linearly from 0.55816 to 0.59989 nm as x varies from 0 to 1. The optical studies of the nanocrystalline ZnSe 1−x Te x films showed that the refractive index increases and fundamental band gap E g decreases from 2.58 to 2.21 eV as the tellurium concentration increases from 0 to 1. Furthermore, it was also found that the variation of E g with composition shows quadratic behavior with bowing parameter equal to 0.105. In addition, the thickness and annealing effects on the structure and optical properties of the deposited films were also investigated. The refractive index dispersion and its dependence on composition were discussed in terms of single oscillator model proposed by Wemple–DiDomenico.

  13. Fabrication of ionic liquid electrodeposited Cu--Sn--Zn--S--Se thin films and method of making

    Science.gov (United States)

    Bhattacharya, Raghu Nath

    2016-01-12

    A semiconductor thin-film and method for producing a semiconductor thin-films comprising a metallic salt, an ionic compound in a non-aqueous solution mixed with a solvent and processing the stacked layer in chalcogen that results in a CZTS/CZTSS thin films that may be deposited on a substrate is disclosed.

  14. Optoelectronic study and annealing stability of room temperature pulsed laser ablated ZnSe polycrystalline thin films

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Taj Muhammad, E-mail: tajakashne@gmail.com; Zakria, M.; Ahmad, Mushtaq; Shakoor, Rana I.

    2014-03-15

    In principal, we described stability of the room temperature ZnSe thin films with thermal annealing deposited onto glass by pulsed laser deposition technique using third harmonic 355 nm of Nd: YAG laser beam. Optoelectronic analysis and stability with thermal annealing was described in terms of structural and optical properties. These properties were investigated via X-ray diffraction, atomic force microscope, scanning electron microscope, Raman, Fourier transform infrared and photoluminescence spectroscopies. From the strong reflection corresponding to the (1 1 1) plane (2θ=27.48°) and the longitudinal optical “LO” phonon modes at 250 cm{sup −1} and 500 cm{sup −1} in the X-ray diffraction and Raman spectra, a polycrystalline zincblende structure of the film was established. At 300 and 350 °C annealing temperatures, the film crystallites were preferentially oriented with the (1 1 1) plane parallel to the substrate and became amorphous at 400 °C. Atomic force microscopic images showed that the morphologies of ZnSe films became smooth with root mean squared roughness 9.86 nm after annealing at 300 and 350 °C while a rougher surface was observed for the amorphous film at 400 °C. Fourier transform infrared study illustrated the chemical nature and Zn–Se bonding in the deposited films. For the as-deposited and annealed samples at 300 and 350 °C, scanning electron micrographs revealed mono-dispersed indistinguishable ZnSe grains and smooth morphological structure which changed to a cracking and bumpy surface after annealing at 400 °C. The physical phenomenon of annealing induced morphological changes could be explained in terms of “structure zone model”. Excitonic emission at 456 nm was observed for both as-deposited and annealed film at 350 °C. The transmission spectrum shows oscillatory behavior because of the thin film interference and exhibited a high degree of transparency down to a wavelength ∼500 nm in the IR region. Energy band-gap was

  15. Improved quantitative analysis of Cu(In,Ga)Se{sub 2} thin films using MCs{sup +}-SIMS depth profiling

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jihye; Kim, Seon Hee; Lee, Kang-Bong; Lee, Yeonhee [Korea Institute of Science and Technology, Advanced Analysis Center, Seoul (Korea, Republic of); Min, Byoung Koun [Korea Institute of Science and Technology, Clean Energy Research Center, Seoul (Korea, Republic of)

    2014-06-15

    The chalcopyrite semiconductor, Cu(InGa)Se{sub 2} (CIGS), is popular as an absorber material for incorporation in high-efficiency photovoltaic devices because it has an appropriate band gap and a high absorption coefficient. To improve the efficiency of solar cells, many research groups have studied the quantitative characterization of the CIGS absorber layers. In this study, a compositional analysis of a CIGS thin film was performed by depth profiling in secondary ion mass spectrometry (SIMS) with MCs{sup +} (where M denotes an element from the CIGS sample) cluster ion detection, and the relative sensitivity factor of the cluster ion was calculated. The emission of MCs{sup +} ions from CIGS absorber elements, such as Cu, In, Ga, and Se, under Cs{sup +} ion bombardment was investigated using time-of-flight SIMS (TOF-SIMS) and magnetic sector SIMS. The detection of MCs{sup +} ions suppressed the matrix effects of varying concentrations of constituent elements of the CIGS thin films. The atomic concentrations of the CIGS absorber layers from the MCs{sup +}-SIMS exhibited more accurate quantification compared to those of elemental SIMS and agreed with those of inductively coupled plasma atomic emission spectrometry. Both TOF-SIMS and magnetic sector SIMS depth profiles showed a similar MCs{sup +} distribution for the CIGS thin films. (orig.)

  16. Electrical and photovoltaic characteristics of CuInSe2 thin films processed by nontoxic Cu–In precursor solutions

    International Nuclear Information System (INIS)

    Choi, Ik Jin; Jang, Jin Woo; Lee, Seung Min; Yeon, Deuk Ho; Jo, Yeon Hwa; Lee, Myung Ho; Cho, Yong Soo; Yun, Jae Ho; Yoon, Kyung Hoon

    2013-01-01

    Nontoxic Cu–In solution-processed CuInSe 2 absorber thin films and resultant photovoltaic cells have been investigated. Acetate-based Cu–In precursors having different Cu/In ratios of 0.8–1.2 were deposited by spin-coating and then selenized in Se atmosphere up to 550 °C. Single tetragonal CuInSe 2 phase was dominantly obtained regardless of Cu/In ratios, with the segregation of Cu 2−x Se secondary phase only in the case of Cu-rich films as evidenced by Raman spectra. The films with the 1.1 ratio demonstrated a larger grain size of ∼1.06 µm with an increased carrier concentration of ∼1.7 × 10 18 cm −3 and a decreased band gap of ∼1.02 eV, compared to the values obtained for Cu-deficient absorber films. The resultant best cell efficiency was ∼3.1% for the absorber having the 1.1 ratio, suggesting a potential of this simple spin-coating method as an alternative to typical vacuum processes. (paper)

  17. Stability of low-carrier-density topological-insulator Bi2Se3 thin films and effect of capping layers

    International Nuclear Information System (INIS)

    Salehi, Maryam; Brahlek, Matthew; Koirala, Nikesh; Moon, Jisoo; Oh, Seongshik; Wu, Liang; Armitage, N. P.

    2015-01-01

    Although over the past number of years there have been many advances in the materials aspects of topological insulators (TIs), one of the ongoing challenges with these materials is the protection of them against aging. In particular, the recent development of low-carrier-density bulk-insulating Bi 2 Se 3 thin films and their sensitivity to air demands reliable capping layers to stabilize their electronic properties. Here, we study the stability of the low-carrier-density Bi 2 Se 3 thin films in air with and without various capping layers using DC and THz probes. Without any capping layers, the carrier density increases by ∼150% over a week and by ∼280% over 9 months. In situ-deposited Se and ex situ-deposited poly(methyl methacrylate) suppress the aging effect to ∼27% and ∼88%, respectively, over 9 months. The combination of effective capping layers and low-carrier-density TI films will open up new opportunities in topological insulators

  18. Effects of Sb-doping on the grain growth of Cu(In, Ga)Se2 thin films fabricated by means of single-target sputtering

    International Nuclear Information System (INIS)

    Zhang, Shu; Wu, Lu; Yue, Ruoyu; Yan, Zongkai; Zhan, Haoran; Xiang, Yong

    2013-01-01

    To investigate the effects of Sb doping on the kinetics of grain growth in Cu(In,Ga)Se 2 (CIGS) thin films during annealing, CIGS thin films were sputtered onto Mo coated substrates from a single CIGS alloy target, followed by chemical bath deposition of Sb 2 S 3 thin layers on top of CIGS layers and subsequent annealing at different temperatures for 30 min in Se vapors. X-ray diffraction results showed that CIGS thin films were obtained directly using the single-target sputtering method. After annealing, the In/Ga ratio in Sb-doped CIGS thin films remained stable compared to undoped film, possibly because Sb can promote the incorporation of Ga into CIGS. The grain growth in CIGS thin films was enhanced after Sb doping, exhibiting significantly larger grains after annealing at 400 °C or 450 °C compared to films without Sb. In particular, the effect was strikingly significant in grain growth across the film thickness, resulting in columnar grain structure in Sb-doped films. This grain growth improvement may be led by the diffusion of Sb from the front surface to the CIGS-Mo back interface, which promoted the mass transport process in CIGS thin films. - Highlights: ► Cu(In,Ga)Se 2 (CIGS) thin films made by sputtering from a single CIGS target. ► Chemical bath deposition used to introduce antimony into CIGS absorber layers. ► In/Ga ratio decreases in Sb-doped annealed films, comparatively to undoped films. ► Sb-doped CIGS films are superior to undoped films in terms of grain-growth kinetics

  19. Effect of substrate temperature on the optical parameters of thermally evaporated Ge-Se-Te thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Pankaj, E-mail: pks_phy@yahoo.co.i [Department of Physics, Jaypee University of Information Technology, Waknaghat, Solan, H.P. 173215 India (India); Katyal, S.C. [Department of Physics, Jaypee University of Information Technology, Waknaghat, Solan, H.P. 173215 India (India)

    2009-05-01

    Thin films of Ge{sub 10}Se{sub 90-x}Te{sub x} (x = 0, 10, 20, 30, 40, 50) glassy alloys were deposited at three substrate temperatures (303 K, 363 K and 423 K) using conventional thermal evaporation technique at base pressure of {approx} 10{sup -4} Pa. X-ray diffraction results show that films deposited at 303 K are of amorphous nature while films deposited at 363 K and 423 K are of polycrystalline nature. The optical parameters, refractive index and optical gap have been derived from the transmission spectra (using UV-Vis-NIR spectrophotometer) of the thin films in the spectral region 400-1500 nm. This has been observed that refractive index values remain almost constant while the optical gap is found to decrease considerably with the increase of substrate temperature. The decrease in optical gap is explained on the basis of change in nature of films, from amorphous to polycrystalline state, with the increase of substrate temperature. The optical gap has also been observed to decrease with the increase of Te content.

  20. γ - irradiation induced effect on the optical parameters of Cu10 Se90 thin films

    International Nuclear Information System (INIS)

    Abu EL-Fadl, A.; Hafiz, M. M.; Aashour, A.S.; Wakaad, M.M.

    2007-01-01

    The optical constants of Cu 10 SE 90 Chalcogenide films successfully deposited by evaporation coating technique have been measured. The absorption coefficient (a) for the as-deposited or after being γ-irradiation at various doses have been computed in the spectral wavelength range 400-900 nm from the transmittance (T) and reflectance (R) measurements of normally-incident light. Both irradiated and as-prepared films showed direct transition. The direct optical band gaps of the films were found to decrease from 2.017 for as prepared to 1.941 eV for γ-irradiation at 190 kGy doses. The width of the tails of localized states E e were calculated and found to be increasing after γ-irradiation. The effects of the γ-irradiation on the refractive index n and extinction coefficient k were studied. Other optical parameters (ε I , ε 2 were calculated at different γ-irradiation doses the obtained values of both ε 1 and ε 2 were found to be incident light and γ-doses dependent. The effect of γ-irradiation on the high-frequency dielectric constant (ε ∞ ) and carrier concentration (N/m * ) is also studied. The change on the degree of disorder as will as the radiation-induced defect changes applied to explain the radiation effects on nature of optical properties Cu 10 SE 90 glasses

  1. Development of a hybrid sputtering/evaporation process for Cu(In,Ga)Se{sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Acciarri, M.; Binetti, S.; Le Donne, A.; Lorenzi, B.; Caccamo, L.; Miglio, L. [Dipartimento di Scienza dei Materiali e Solar Energy Research Center MIB-SOLAR, Universita di Milano Bicocca, Milan (Italy); Moneta, R.; Marchionna, S.; Meschia, M. [Voltasolar s.r.l, Turate (Italy)

    2011-08-15

    In this paper we report a new method for Cu(In,Ga)Se{sub 2} deposition for solar cell application. Differently from the common co-evaporation process, an alterative approach for thin film Cu(In,Ga)Se{sub 2} has been tested: the sputtering deposition of metal elements combined with the selenium evaporation. We have studied the relationships between the growth parameters of our hybrid sputtering/evaporation method and the chemical-physical properties of the CIGS films. The cells are completed with a CdS buffer layer deposited by chemical bath deposition and ZnO + ITO deposited by RF sputtering. Test solar cells of 0.5 cm{sup 2} have shown an efficiency of 10% and 2.5% on glass and stainless steel substrate respectively. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Processing and characterisation of II–VI ZnCdMgSe thin film gain structures

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Brynmor E., E-mail: brynmor.jones@strath.ac.uk [Institute of Photonics, Department of Physics, University of Strathclyde, Technology and Innovation Centre, Level 5, 99 George Street, Glasgow G1 1RD (United Kingdom); Schlosser, Peter J. [Institute of Photonics, Department of Physics, University of Strathclyde, Technology and Innovation Centre, Level 5, 99 George Street, Glasgow G1 1RD (United Kingdom); De Jesus, Joel [Department of Physics, The Graduate Center and The City College of New York, 138th Street and Convent Avenue, New York, NY 10031 (United States); Garcia, Thor A.; Tamargo, Maria C. [Department of Chemistry, The Graduate Center and The City College of New York, 138th Street and Convent Avenue, New York, NY 10031 (United States); Hastie, Jennifer E. [Institute of Photonics, Department of Physics, University of Strathclyde, Technology and Innovation Centre, Level 5, 99 George Street, Glasgow G1 1RD (United Kingdom)

    2015-09-01

    Lattice-matched II–VI selenide quantum well (QW) structures grown on InP substrates can be designed for emission throughout the visible spectrum. InP has, however, strong visible-light absorption, so that a method for epitaxial lift-off and transfer to transparent substrates is desirable for vertically-integrated devices. We have designed and grown, via molecular beam epitaxy, ZnCdSe/ZnCdMgSe multi-QW gain regions for vertical emission, with the QWs positioned for resonant periodic gain. The release of the 2.7 μm-thick ZnCdSe/ZnCdMgSe multi-QW film is achieved via selective wet etching of the substrate and buffer layers leaving only the epitaxial layers, which are subsequently transferred to transparent substrates, including glass and thermally-conductive diamond. Post-transfer properties are investigated, with power and temperature-dependent surface- and edge-emitting photoluminescence measurements demonstrating no observable strain relaxation effects or significant shift in comparison to unprocessed samples. The temperature dependent QW emission shift is found experimentally to be 0.13 nm/K. Samples capillary-bonded epitaxial-side to glass exhibited a 6 nm redshift under optical pumping of up to 35 mW at 405 nm, corresponding to a 46 K temperature increase in the pumped region; whereas those bonded to diamond exhibited no shift in QW emission, and thus efficient transfer of the heat from the pumped region. Atomic force microscopy analysis of the etched surface reveals a root-mean-square roughness of 3.6 nm. High quality optical interfaces are required to establish a good thermal and optical contact for high power optically pumped laser applications. - Highlights: • ZnCdSe/ZnCdMgSe II–VI multi-quantum well active regions are grown on InP. • Free-standing, II–VI films removed from InP substrate and InGaAs via wet etching • Negligible change of the quantum well photoluminescence after substrate removal • II–VI film transferred to diamond shows good

  3. Soft x-ray photoemission investigation of the oxidation of CuInSe/sub 2/ thin films

    International Nuclear Information System (INIS)

    Zurcher, P.; Nelson, A.J.; Johnson, P.; Lapeyre, G.J.; Noufi, R.

    1987-01-01

    CuInSe/sub 2/ films are used as absorber layers in heterojunction thin film solar cells. It has been demonstrated that, depending on the stoichiometry, oxygen annealing can make CuInSe/sub 2/ films more p-type or even convert n-type films into p-type while subsequent reduction with hydrazine will reverse such processes. Using synchrotron radiation soft x-ray photoemission spectroscopy, the authors found associated with the hydrazine reduced films an In1+ state that converts into In3+ under the influence of oxygen at elevated sample temperatures. The samples investigated were grown in a way that the top several thousand Angstroms are increasingly Cu-poor and In-rich. It is this region which is sampled by the surface sensitive technique of photoemission. The Cu-poor/In-rich top regions will most likely have a large number of intrinsic In on Cu-site defects leaving the In in a 1+ state. All the oxidation and reduction results and the associated changes in majority carrier concentrations and type conversions can be understood in terms of oxygem/In/sub Cu/-defect interactions

  4. Preparation of thin films, with base to precursor materials of type Cu-In-Se elaborated by electrodeposition for the solar cells elaboration

    International Nuclear Information System (INIS)

    Fernandez, A.M.

    1999-01-01

    Thin films of chalcogenide compounds are promising because they have excellent optoelectronic characteristics to be applied in solar cells. In particular, CuInSe 2 and Cd Te thin films have shown high solar to electrical conversion efficiency. However, this efficiency is limited by the method of preparation, in this case, physical vapor deposition techniques are used. In order to increase the area of deposition t is necessary to use chemical methods, for example, electrodeposition technique. In this paper, the preparation of Cu-In-Se precursors thin films by electrochemical method is reported. These precursors were used to build solar cells with 7.9 % of efficiency. (Author)

  5. Fabrication of a Cu(InGaSe2 Thin Film Photovoltaic Absorber by Rapid Thermal Annealing of CuGa/In Precursors Coated with a Se Layer

    Directory of Open Access Journals (Sweden)

    Chun-Yao Hsu

    2013-01-01

    Full Text Available Cu(InGaSe2 (CIGS thin film absorbers are prepared using sputtering and selenization processes. The CuGa/In precursors are selenized during rapid thermal annealing (RTA, by the deposition of a Se layer on them. This work investigates the effect of the Cu content in precursors on the structural and electrical properties of the absorber. Using X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, and Hall effect measurement, it is found that the CIGS thin films produced exhibit facetted grains and a single chalcopyrite phase with a preferred orientation along the (1 1 2 plane. A Cu-poor precursor with a Cu/( ratio of 0.75 demonstrates a higher resistance, due to an increase in the grain boundary scattering and a reduced carrier lifetime. A Cu-rich precursor with a Cu/( ratio of 1.15 exhibits an inappropriate second phase ( in the absorber. However, the precursor with a Cu/( ratio of 0.95 exhibits larger grains and lower resistance, which is suitable for its application to solar cells. The deposition of this precursor on Mo-coated soda lime glass substrate and further RTA causes the formation of a MoSe2 layer at the interface of the Mo and CIGS.

  6. Distinctive orbital anisotropy observed in the nematic state of a FeSe thin film

    International Nuclear Information System (INIS)

    Zhang, Y.; Lawrence Berkeley National Laboratory; Yi, M.; Stanford University, CA; Liu, Z.-K.

    2016-01-01

    Nematic state, where the system is translationally invariant but breaks the rotational symmetry, has drawn great attentions recently due to experimental observations of such a state in both cuprates and iron-based superconductors. The mechanism of nematicity that is likely tied to the pairing mechanism of high-T c , however, still remains controversial. Here, we studied the electronic structure of multilayer FeSe film by angle-resolved photoemission spectroscopy (ARPES). We found that the FeSe film enters the nematic state around 125 K, while the electronic signature of long range magnetic order has not been observed down to 20K indicating the non-magnetic origin of the nematicity. The band reconstruction in the nematic state is characterized by the splitting of the d xz and d yz bands. More intriguingly, such energy splitting is strong momentum dependent with the largest band splitting of ~80 meV at the zone corner. The simple on-site ferro-orbital ordering is insufficient to reproduce the nontrivial momentum dependence of the band reconstruction. Instead, our results suggest that the nearest-neighbor hopping of d xz and d yz is highly anisotropic in the nematic state, the origin of which holds the key in understanding the nematicity in iron-based superconductors.

  7. Structure and photoelectrochemistry of silver-copper-indium-diselenide ((AgCu)InSe2) thin film

    Science.gov (United States)

    Zhang, Lin Rui; Li, Tong; Wang, Hao; Pang, Wei; Chen, Yi Chuan; Song, Xue Mei; Zhang, Yong Zhe; Yan, Hui

    2018-02-01

    In this work, silver (Ag) precursors with different thicknesses were sputtered on the surfaces of CuIn alloys, and (AgCu)InSe2 (ACIS) films were formed after selenization at 550 °C under nitrogen condition using a rapid thermal process furnace. The structure and electrical properties of the ACIS films were investigated. The result showed that the distribution of Ag+ ion was more uniform with increasing the thickness of Ag precursor, and the surface of the thin-film became more homogeneous and denser. When Ag/Cu ratio ≥0.249, the small grain particles disappeared. The band gap can be rationally controlled by adjusting Ag content. When (Ag + Cu)/In ratio ≥ 1.15, the surface of the ACIS thin-film mainly exhibited n-type semiconductor. Through the photoelectrochemistry measurement, it was observed that the incorporation of Ag+ ions could improve photocurrent by adjusting the band gap. With the Ag precursor thickness increased, the dark current decreased at the more negative potential.

  8. Advances in Cost-Efficient Thin-Film Photovoltaics Based on Cu(In,Ga)Se2

    Institute of Scientific and Technical Information of China (English)

    Michael Powalla; Stefan Paetel; Dimitrios Hariskos; Roland Wuerz; Friedrich Kessler; Peter Lechner; Wiltraud Wischmann; Theresa Magorian Friedlmeier

    2017-01-01

    In this article,we discuss the leading thin-film photovoltaic (PV) technology based on the Cu(In,Ga)Se2 (CIGS)compound semiconductor.This contribution includes a general comparison with the conventional Si-wafer-based PV technology and discusses the basics of the CIGS technology as well as advances in worldrecord-level conversion efficiency,production,applications,stability,and future developments with respect to a flexible product.Once in large-scale mass production,the CIGS technology has the highest potential of all PV technologies for cost-efficient clean energy generation.

  9. Improving stability of photoluminescence of ZnSe thin films grown by molecular beam epitaxy by incorporating Cl dopant

    International Nuclear Information System (INIS)

    Wang, J. S.; Shen, J. L.; Chen, W. J.; Tsai, Y. H.; Wang, H. H.; Yang, C. S.; Chen, R. H.; Tsai, C. D.

    2011-01-01

    This investigation studies the effect of chlorine (Cl) dopant in ZnSe thin films that were grown by molecular beam epitaxy on their photoluminescence (PL) and the stability thereof. Free excitonic emission was observed at room-temperature in the Cl-doped sample. Photon irradiation with a wavelength of 404 nm and a power density of 9.1 W/cm 2 has a much stronger effect on PL degradation than does thermal heating to a temperature of 150 deg. C. Additionally, this study shows that the generation of nonradiative centers by both photon irradiation and thermal heating can be greatly inhibited by incorporating Cl dopant.

  10. Advances in Cost-Efficient Thin-Film Photovoltaics Based on Cu(In,GaSe2

    Directory of Open Access Journals (Sweden)

    Michael Powalla

    2017-08-01

    Full Text Available In this article, we discuss the leading thin-film photovoltaic (PV technology based on the Cu(In,GaSe2 (CIGS compound semiconductor. This contribution includes a general comparison with the conventional Si-wafer-based PV technology and discusses the basics of the CIGS technology as well as advances in world-record-level conversion efficiency, production, applications, stability, and future developments with respect to a flexible product. Once in large-scale mass production, the CIGS technology has the highest potential of all PV technologies for cost-efficient clean energy generation.

  11. Electronic grain boundary properties in polycrystalline Cu(In,Ga)Se2 semiconductors for thin film solar cells

    International Nuclear Information System (INIS)

    Baier, Robert

    2012-01-01

    Solar cells based on polycrystalline Cu(In,Ga)Se 2 (CIGSe) thin film absorbers reach the highest energy conversion efficiency among all thin film solar cells. The record efficiency is at least partly attributed to benign electronic properties of grain boundaries (GBs) in the CIGSe layers. However, despite a high amount of research on this phenomenon the underlying physics is not sufficiently understood. This thesis presents an elaborate study on the electronic properties of GBs in CIGSe thin films. Kelvin probe force microscopy (KPFM) was employed to investigate the electronic properties of GBs in dependence of the Ga-content. Five CIGSe thin lms with various Ga-contents were grown by means of similar three stage co-evaporation processes. Both as grown as well as chemically treated (KCN etched) thin films were analyzed. The chemical treatment was employed to remove surface oxides. No difference in electronic GB properties was found with or without the chemical treatment. Therefore, we conclude that a moderate surface oxidation does not alter the electronic properties of GBs. In general, one can observe significant variations of electronic potential barriers at GBs. Under consideration of the averaging effect of the work function signal of nanoscale potential distributions in KPFM measurements which was quantified in the course of this thesis both positive and negative potential barriers in a range between ∼-350 mV and ∼+450 mV were detected. Additionally, variations in the defect densities at GBs between ∼3.1 x 10 11 cm -2 and ∼2.1 x 10 12 cm -2 were found. However, no correlation between the electronic properties of GBs and the Ga-content of CIGSe thin films was discovered. Consequently, one cannot explain the drop in device efficiency observed for CIGSe thin film solar cells with a high Ga-content by a change of the electronic properties of GBs. Combined KPFM and electron backscatter diffraction measurements were employed for the first time on CIGSe thin

  12. Electronic grain boundary properties in polycrystalline Cu(In,Ga)Se{sub 2} semiconductors for thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Baier, Robert

    2012-06-25

    Solar cells based on polycrystalline Cu(In,Ga)Se{sub 2} (CIGSe) thin film absorbers reach the highest energy conversion efficiency among all thin film solar cells. The record efficiency is at least partly attributed to benign electronic properties of grain boundaries (GBs) in the CIGSe layers. However, despite a high amount of research on this phenomenon the underlying physics is not sufficiently understood. This thesis presents an elaborate study on the electronic properties of GBs in CIGSe thin films. Kelvin probe force microscopy (KPFM) was employed to investigate the electronic properties of GBs in dependence of the Ga-content. Five CIGSe thin lms with various Ga-contents were grown by means of similar three stage co-evaporation processes. Both as grown as well as chemically treated (KCN etched) thin films were analyzed. The chemical treatment was employed to remove surface oxides. No difference in electronic GB properties was found with or without the chemical treatment. Therefore, we conclude that a moderate surface oxidation does not alter the electronic properties of GBs. In general, one can observe significant variations of electronic potential barriers at GBs. Under consideration of the averaging effect of the work function signal of nanoscale potential distributions in KPFM measurements which was quantified in the course of this thesis both positive and negative potential barriers in a range between ∼-350 mV and ∼+450 mV were detected. Additionally, variations in the defect densities at GBs between ∼3.1 x 10{sup 11} cm{sup -2} and ∼2.1 x 10{sup 12} cm{sup -2} were found. However, no correlation between the electronic properties of GBs and the Ga-content of CIGSe thin films was discovered. Consequently, one cannot explain the drop in device efficiency observed for CIGSe thin film solar cells with a high Ga-content by a change of the electronic properties of GBs. Combined KPFM and electron backscatter diffraction measurements were employed for the

  13. Nanoscale observation of surface potential and carrier transport in Cu2ZnSn(S,Se)4 thin films grown by sputtering-based two-step process.

    Science.gov (United States)

    Kim, Gee Yeong; Kim, Ju Ri; Jo, William; Son, Dae-Ho; Kim, Dae-Hwan; Kang, Jin-Kyu

    2014-01-08

    Stacked precursors of Cu-Zn-Sn-S were grown by radio frequency sputtering and annealed in a furnace with Se metals to form thin-film solar cell materials of Cu2ZnSn(S,Se)4 (CZTSSe). The samples have different absorber layer thickness of 1 to 2 μm and show conversion efficiencies up to 8.06%. Conductive atomic force microscopy and Kelvin probe force microscopy were used to explore the local electrical properties of the surface of CZTSSe thin films. The high-efficiency CZTSSe thin film exhibits significantly positive bending of surface potential around the grain boundaries. Dominant current paths along the grain boundaries are also observed. The surface electrical parameters of potential and current lead to potential solar cell applications using CZTSSe thin films, which may be an alternative choice of Cu(In,Ga)Se2.PACS number: 08.37.-d; 61.72.Mm; 71.35.-y.

  14. Strength, stiffness, and microstructure of Cu(In,Ga)Se2 thin films deposited via sputtering and co-evaporation

    International Nuclear Information System (INIS)

    Luo, Shi; Jang, Dongchan; Greer, Julia R.; Lee, Jiun-Haw; Liu, Chee-Wee; Shieh, Jia-Min; Shen, Chang-Hong; Wu, Tsung-Ta

    2014-01-01

    This work examines Cu(In,Ga)Se 2 thin films fabricated by (1) selenization of pre-sputtered Cu-In-Ga and (2) co-evaporation of each constituent. The efficiency disparity between films deposited via these two methods is linked to differences in morphology and microstructure. Atomic force microscopy and scanning electron microscopy show that selenized films have rougher surfaces and poor adhesion to molybdenum back contact. Transmission electron microscopy and electron energy loss spectroscopy revealed multiple voids near the Mo layer in selenized films and a depletion of Na and Se around the voids. Residual stresses in co-evaporated films were found to be ∼1.23 GPa using wafer curvature measurements. Uniaxial compression experiments on 500 nm-diameter nanopillars carved out from co-evaporated films revealed the elastic modulus of 70.4 ± 6.5 GPa. Hertzian contact model applied to nanoindentation data on selenized films revealed the indentation modulus of 68.9 ± 12.4 GPa, which is in agreement with previous reports. This equivalence of the elastic moduli suggests that microstructural differences manifest themselves after the yield point. Typical plastic behavior with two distinct failure modes is observed in the extracted stress-strain results, with the yield strength of 640.9 ± 13.7 MPa for pillars that failed by shearing and 1100.8 ± 77.8 MPa for pillars that failed by shattering.

  15. Physical, optical and electrical properties of copper selenide (CuSe) thin films deposited by solution growth technique at room temperature

    International Nuclear Information System (INIS)

    Gosavi, S.R.; Deshpande, N.G.; Gudage, Y.G.; Sharma, Ramphal

    2008-01-01

    Copper selenide (CuSe) thin films are grown onto amorphous glass substrate from an aqueous alkaline medium using solution growth technique (SGT) at room temperature. The preparative parameters were optimized to obtain good quality of thin films. The as-deposited films were characterized for physical, optical and electrical properties. X-ray diffraction (XRD) pattern reveals that the films are polycrystalline in nature. Energy dispersive analysis by X-ray (EDAX) shows formation of stoichiometric CuSe compound. Uniform deposition of CuSe thin films on glass substrate was observed from scanning electron microscopy (SEM) and atomic force microscopy (AFM) micrographs. Average grain size was determined to 144.53 ± 10 nm using atomic force microscopy. The band gap was found to be 2.03 eV with direct band-to-band transition. Semi-conducting behaviour was observed from resistivity measurements. Ohmic behaviour was seen from I-V curve with good electrical conductivity

  16. Study of the optical properties and structure of ZnSe/ZnO thin films grown by MOCVD with varying thicknesses

    Energy Technology Data Exchange (ETDEWEB)

    Jabri, S., E-mail: slaheddine.jabri@fst.rnu.tn [Unité des nanomatériaux et photoniques, Faculté des Sciences de Tunis, Campus Universitaire Ferhat Hachad, El Manar, 2092 Tunis (Tunisia); Amiri, G.; Sallet, V. [Groupe d’Etude de la Matière Condensée, CNRS-Université de Versailles St Quentin, Université Paris-Saclay, 45 avenue des Etats Unis, 78035 Versailles Cedex (France); Souissi, A. [Laboratoire de Photovoltaïque, Centre de Recherches et des Technologies de l’Energie, Technopole Borj Cedria, B.P. 95, Hammammlif 2050 (Tunisia); Meftah, A. [Unité des nanomatériaux et photoniques, Faculté des Sciences de Tunis, Campus Universitaire Ferhat Hachad, El Manar, 2092 Tunis (Tunisia); Galtier, P. [Groupe d’Etude de la Matière Condensée, CNRS-Université de Versailles St Quentin, Université Paris-Saclay, 45 avenue des Etats Unis, 78035 Versailles Cedex (France); Oueslati, M. [Unité des nanomatériaux et photoniques, Faculté des Sciences de Tunis, Campus Universitaire Ferhat Hachad, El Manar, 2092 Tunis (Tunisia)

    2016-05-15

    ZnSe layers were grown on ZnO substrates by the metal organic chemical vapor deposition technique. A new structure appeared at lower thicknesses films. The structural properties of the thin films were studied by the X-ray diffraction (XRD) and Raman spectroscopy methods. First, Raman selection rules are explicitly put forward from a theoretical viewpoint. Second, experimentally-retrieved-intensities of the Raman signal as a function of polarization angle of incident light are fitted to the obtained theoretical dependencies in order to confirm the crystallographic planes of zinc blend ZnSe thin film, and correlate with DRX measurements. Raman spectroscopy has been used to characterize the interfacial disorder that affects energy transport phenomena at ZnSe/ZnO interfaces and the Photoluminescence (PL) near the band edge of ZnSe thin films.

  17. Surface treatments and properties of CuGaSe{sub 2} thin films for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Nishiwaki, S.; Ennaoui, A.; Schuler, S.; Siebentritt, S.; Lux-Steiner, M.Ch

    2003-05-01

    Polycrystalline CuGaSe{sub 2} (CGS) films with slightly Ga-rich composition were prepared on Mo/soda-lime substrates by the 'bi-layer' process. The film surfaces were modified by chemical bath treatment with In{sub 2}(SO{sub 4}){sub 3}, thioacetamid, and triethanolamin to improve the performance in solar cell applications. The film compositions were characterized by X-ray fluorescence and the surface of treated films was investigated by X-ray photoelectron spectroscopy (XPS). Solar cells with ZnO/CdS/CGS/Mo/soda-lime glass structure were fabricated, and the current-voltage properties and the quantum efficiency were analyzed. Improvement of the spectral response, especially in the long wavelength region, was observed for the samples treated with the chemical bath, which results in increase in a short circuit current density. An increase in the parallel and series resistance of the cells was also observed with the treatment. The surface compositions of the CGS thin films modified by the chemical bath are discussed on the base of the results of XPS.

  18. Fermi-level tuning of the Dirac surface state in (Bi1-x Sb x )2Se3 thin films

    Science.gov (United States)

    Satake, Yosuke; Shiogai, Junichi; Takane, Daichi; Yamada, Keiko; Fujiwara, Kohei; Souma, Seigo; Sato, Takafumi; Takahashi, Takashi; Tsukazaki, Atsushi

    2018-02-01

    We report on the electronic states and the transport properties of three-dimensional topological insulator (Bi1-x Sb x )2Se3 ternary alloy thin films grown on an isostructural Bi2Se3 buffer layer on InP substrates. By angle-resolved photoemission spectroscopy, we clearly detected Dirac surface states with a large bulk band gap of 0.2-0.3 eV in the (Bi1-x Sb x )2Se3 film with x  =  0.70. In addition, we observed by Hall effect measurements that the dominant charge carrier converts from electron (n-type) to hole (p-type) at around x  =  0.7, indicating that the Fermi level can be controlled across the Dirac point. Indeed, the carrier transport was shown to be governed by Dirac surface state in 0.63  ⩽  x  ⩽  0.75. These features suggest that Fermi-level tunable (Bi1-x Sb x )2Se3-based heterostructures provide a platform for extracting exotic topological phenomena.

  19. Studies on Inx(As2Se31-x thin films using variable angle spectroscopic ellipsometry (VASE

    Directory of Open Access Journals (Sweden)

    Amin G. A. M.

    2015-09-01

    Full Text Available The results of multi-angle ellipsometrical measurements of thermally evaporated Inx(As2Se31-x (x = 0, 0.01,0.05 films are presented. Optical parameters n and Es of thin Inx(As2Se31-x films show that indium atoms were incorporated into the host matrix of As2Se3 forming distinct features depending on the indium concentration. Refractive index, n, was found to decrease with the addition of In to the binary As2Se3. The real and imaginary parts of the dielectric function, ε' and ε" were also calculated from the obtained data and correlated with In concentration. It was found that e' decreases with the increase of In content while ε" increases with the increase of In content. Absorption edge is shifted towards lower photon energy with the increase of In content. As a result, the optical energy gap decreases with increasing In content. This has been correlated with the chemical character of the additive as well as with the structural and bonding aspects of the amorphous composition. Nonlinear optical constants (χ(3 and n2 were determined from linear optical parameters using semi-empirical relations in the long wavelength limit.

  20. Studies on Cd1Se0.6Te0.4 Thin Films by Spectroscopic and Diffractometer Characterization

    Directory of Open Access Journals (Sweden)

    Cliff Orori Mosiori

    2017-09-01

    Full Text Available Cadmium selenide tellurium is a compound containing cadmium, tellurium and selenium elements forming a combined solid. Hall measurements suggest that it is an n-type semiconductor. Related optical studies indicate that is transparent to infra-red radiation. Structural studies clearly show that it has a wurtzite, sphalerite crystalline forms. Cadmium is a toxic heavy metal, and selenium is only toxic in large amounts or doses. By this toxicity, cadmium selenide is a known to be carcinogen to humans; however, this does not stop investigating it for optoelectronic applications. Current research has narrowed down to investigating cadmium selenide when in the form of nanoparticles. Cadmium selenide finds applications has found applications in opto-electronic devices like laser diodes, biomedical imaging, nano-sensing, high-efficiency solar cells and thin-film transistors. By chemical bath deposition, Cd1Se0.6Te0.4 thin films were grown onto glass. Tellurium was gradually introduced as an impurity and its crystalline structure and optical properties were investigated by XRD and UV-VIS spectroscopy. The main Cd1Se0.6Te0.4/glass characteristics were correlated with the conditions of growing and post-growth treatment and it was found out that films were homogeneous films with controllable thickness onto the glass substrate and suitable for n-type “sandwich” heterostructures applications. Comparison of the intensities of equivalent reflexions provided a test for the internal consistency of the measurements. Equivalent reflexions in two specimens differed on average by 1.4 % and 0.6% from the mean measured intensity, attesting to the high internal consistency of measurements from extended-face crystals. By comparison from data obtained from all samples showed their average deviation from the mean to be 0.9 %.

  1. Effect of deposition temperature on the structural and optical properties of CdSe QDs thin films deposited by CBD method

    International Nuclear Information System (INIS)

    Laatar, F.; Harizi, A.; Smida, A.; Hassen, M.; Ezzaouia, H.

    2016-01-01

    Highlights: • Synthesis of CdSe QDs with L-Cysteine capping agent for applications in nanodevices. • The films of CdSe QDs present uniform and good dispersive particles at the surface. • Effect of bath temperature on the structural and optical properties of CdSe QDs thin films. • Investigation of the optical constants and dispersion parameters of CdSe QDs thin films. - Abstract: Cadmium selenide quantum dots (CdSe QDs) thin films were deposited onto glass substrates by a chemical bath deposition (CBD) method at different temperatures from an aqueous solution containing L-Cysteine (L-Cys) as capping agent. The evolution of the surface morphology and elemental composition of the CdSe films were studied by AFM, SEM, and EDX analyses. Structural and optical properties of CdSe thin films were investigated by XRD, UV–vis and PL spectroscopy. The dispersion behavior of the refractive index is described using the single oscillator Wemple-DiDomenico (W-D) model, and the physical dispersion parameters are calculated as a function of deposition temperature. The dispersive optical parameters such as average oscillator energy (E_o), dispersion energy (E_d), and static refractive index (n_o) were found to vary with the deposition temperature. Besides, the electrical free carrier susceptibility (χ_e) and the carrier concentration of the effective mass ratio (N/m*) were evaluated according to the Spitzer-Fan model.

  2. Effect of deposition temperature on the structural and optical properties of CdSe QDs thin films deposited by CBD method

    Energy Technology Data Exchange (ETDEWEB)

    Laatar, F., E-mail: fakher8laatar@gmail.com [Photovoltaic Laboratory, Centre for Research and Technology Energy, Tourist Route Soliman, BP 95, 2050 Hammam-Lif (Tunisia); Harizi, A. [Photovoltaic and Semiconductor Materials Laboratory, Engineering Industrial Department, ENIT, Tunis El Manar University, BP 37, Le Belvédère, 1002 Tunis (Tunisia); Smida, A. [Photovoltaic Laboratory, Centre for Research and Technology Energy, Tourist Route Soliman, BP 95, 2050 Hammam-Lif (Tunisia); Hassen, M. [Photovoltaic Laboratory, Centre for Research and Technology Energy, Tourist Route Soliman, BP 95, 2050 Hammam-Lif (Tunisia); Higher Institute of Applied Science and Technology of Sousse, City Taffala (Ibn Khaldun), 4003 Sousse (Tunisia); Ezzaouia, H. [Photovoltaic Laboratory, Centre for Research and Technology Energy, Tourist Route Soliman, BP 95, 2050 Hammam-Lif (Tunisia)

    2016-06-15

    Highlights: • Synthesis of CdSe QDs with L-Cysteine capping agent for applications in nanodevices. • The films of CdSe QDs present uniform and good dispersive particles at the surface. • Effect of bath temperature on the structural and optical properties of CdSe QDs thin films. • Investigation of the optical constants and dispersion parameters of CdSe QDs thin films. - Abstract: Cadmium selenide quantum dots (CdSe QDs) thin films were deposited onto glass substrates by a chemical bath deposition (CBD) method at different temperatures from an aqueous solution containing L-Cysteine (L-Cys) as capping agent. The evolution of the surface morphology and elemental composition of the CdSe films were studied by AFM, SEM, and EDX analyses. Structural and optical properties of CdSe thin films were investigated by XRD, UV–vis and PL spectroscopy. The dispersion behavior of the refractive index is described using the single oscillator Wemple-DiDomenico (W-D) model, and the physical dispersion parameters are calculated as a function of deposition temperature. The dispersive optical parameters such as average oscillator energy (E{sub o}), dispersion energy (E{sub d}), and static refractive index (n{sub o}) were found to vary with the deposition temperature. Besides, the electrical free carrier susceptibility (χ{sub e}) and the carrier concentration of the effective mass ratio (N/m*) were evaluated according to the Spitzer-Fan model.

  3. Comparative study of ZnSe thin films deposited from modified chemical bath solutions with ammonia-containing and ammonia-free precursors

    International Nuclear Information System (INIS)

    Chen Liangyan; Zhang Daoli; Zhai Guangmei; Zhang Jianbing

    2010-01-01

    Ammonia is one of the complexing agents which are the most commonly used in the precursors of ZnSe thin films by chemical bath deposition, but its high volatility may be harmful to human beings and environments. In our experiments, ZnSe films were obtained from modified chemical solutions with ammonia-containing and ammonia-free precursors. X-ray diffraction, field-emission scanning electron microscope (FSEM), and absorption spectrum were applied to investigate the microstructure, morphology and optical properties of the samples obtained from both growth conditions, which were investigated in this work. The ammonia-free chemical bath deposited ZnSe films showed comparable properties with the ammonia-containing ones, indicating that ZnSe films from ammonia-free chemical solution may be preferred buffer layer in thin film solar cells with less environmental contamination.

  4. Combinatorial investigation of the effects of sodium on Cu 2ZnSnSe4 polycrystalline thin films

    Science.gov (United States)

    Gibbs, Alex Hilton

    Cu2ZnSnSe4 (CZTSe) possess highly suitable optical and electronic properties for use as an absorber layer in thin film solar cells. CZTSe also has potential to achieve terawatt level solar energy production due to its inexpensive and abundant material constituents. Currently, fabricating CZTSe devices with the expected theoretical performance has not been achieved, making the growth and formation of CZTSe an interesting topic of research. In this work, a two-step vacuum fabrication process consisting of RF co-sputtering followed by reactive annealing was explored as a viable technique for synthesizing CZTSe thin films. Furthermore, the enhancement of the fabrication process by the incorporation of sodium during annealing was studied using a combinatorial approach. Film composition was analyzed using electron dispersive spectroscopy. Structure, phase morphology, and formation were determined using scanning electron microscopy, x-ray diffraction, atomic force microscopy and raman spectroscopy. Optical and electronic properties were characterized using UV-Vis and Voc were measurements under a one sun solar simulator. RF co-sputtering CuSe, ZnSe, and SnSe precursors produced films with good thickness uniformity, adhesion and stoichiometry control over 3 x 3 in 2 substrates. Composition measurements showed that the precursor films maintained stability during an annealing process of 580° C for 20 minutes producing near stoichiometric CZTSe. However, grain size was small with an average diameter of 350 nm. The CZTSe film produced by this process exhibited a suitable absorption coefficient of > 104 cm-1 and aband gap near 1.0 eV. The film also produced an XRD pattern consistent with tetragonal CZTSe with no secondary phase formation with the exception of approximately 12.5 nm of interfacial MoSe2 formation at the back contact. The combinatorial investigation of the influence of sodium on CZTSe growth and morphology was achieved using a custom built constant withdraw

  5. Tuning Bandgap of p-Type Cu2Zn(Sn, Ge)(S, Se)4 Semiconductor Thin Films via Aqueous Polymer-Assisted Deposition.

    Science.gov (United States)

    Yi, Qinghua; Wu, Jiang; Zhao, Jie; Wang, Hao; Hu, Jiapeng; Dai, Xiao; Zou, Guifu

    2017-01-18

    Bandgap engineering of kesterite Cu 2 Zn(Sn, Ge)(S, Se) 4 with well-controlled stoichiometric composition plays a critical role in sustainable inorganic photovoltaics. Herein, a cost-effective and reproducible aqueous solution-based polymer-assisted deposition approach is developed to grow p-type Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films with tunable bandgap. The bandgap of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films can be tuned within the range 1.05-1.95 eV using the aqueous polymer-assisted deposition by accurately controlling the elemental compositions. One of the as-grown Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films exhibits a hall coefficient of +137 cm 3 /C. The resistivity, concentration and carrier mobility of the Cu 2 ZnSn(S, Se) 4 thin film are 3.17 ohm·cm, 4.5 × 10 16 cm -3 , and 43 cm 2 /(V·S) at room temperature, respectively. Moreover, the Cu 2 ZnSn(S, Se) 4 thin film when used as an active layer in a solar cell leads to a power conversion efficiency of 3.55%. The facile growth of Cu 2 Zn(Sn, Ge)(S, Se) 4 thin films in an aqueous system, instead of organic solvents, provides great promise as an environmental-friendly platform to fabricate a variety of single/multi metal chalcogenides for the thin film industry and solution-processed photovoltaic devices.

  6. Electrochemical preparation and characterization of n-CdSe sub 0. 65 Te sub 0. 35 polycrystalline thin films: Influence of annealing

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, M T; Ortega, J [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain). Inst. de Energias Renovables

    1989-12-01

    CdSe{sub 0.65}Te{sub 0.35} thin films have been prepared by electrodeposition. The films were characterized by X-ray diffraction, optical and photoelectrochemical methods. The influence of annealing treatments on the physical parameters (grain size, d, donor concentration, N{sub D}, and hole diffusion length, L{sub P}) determining the photoelectrochemical behaviour of electrodeposited CdSe{sub 0.65}Te{sub 0.35} thin films in contact with sulfide/polysulfide electrolytes have been systematically studied. (orig.).

  7. Photoacoustic spectroscopy of thin films of As2S3, As2Se3 and GeSe2

    Indian Academy of Sciences (India)

    Photoacoustic spectroscopy (PAS) is one of the important branches of spectroscopy, which enables one to detect light-induced heat production following the absorption of pulsed radiation by the sample. As2S3, As2Se3 and GeSe2 exhibit a wide variety of photo-induced phenomena that enable them to be used as optical ...

  8. X-ray magnetic spectroscopy of MBE-grown Mn-doped Bi2Se3 thin films

    Directory of Open Access Journals (Sweden)

    L. J. Collins-McIntyre

    2014-12-01

    Full Text Available We report the growth of Mn-doped Bi2Se3 thin films by molecular beam epitaxy (MBE, investigated by x-ray diffraction (XRD, atomic force microscopy (AFM, SQUID magnetometry and x-ray magnetic circular dichroism (XMCD. Epitaxial films were deposited on c-plane sapphire substrates by co-evaporation. The films exhibit a spiral growth mechanism typical of this material class, as revealed by AFM. The XRD measurements demonstrate a good crystalline structure which is retained upon doping up to ∼7.5 atomic-% Mn, determined by Rutherford backscattering spectrometry (RBS, and show no evidence of the formation of parasitic phases. However an increasing interstitial incorporation of Mn is observed with increasing doping concentration. A magnetic moment of 5.1 μB/Mn is obtained from bulk-sensitive SQUID measurements, and a much lower moment of 1.6 μB/Mn from surface-sensitive XMCD. At ∼2.5 K, XMCD at the Mn L2,3 edge, reveals short-range magnetic order in the films and indicates ferromagnetic order below 1.5 K.

  9. Compositional effects in Ag_2ZnSnSe_4 thin films and photovoltaic devices

    International Nuclear Information System (INIS)

    Gershon, Talia; Sardashti, Kasra; Lee, Yun Seog; Gunawan, Oki; Singh, Saurabh; Bishop, Douglas; Kummel, Andrew C.; Haight, Richard

    2017-01-01

    Ag_2ZnSnSe_4 (AZTSe) is a relatively new n-type photovoltaic (PV) absorber material which has recently demonstrated a conversion efficiency of ∼5% in a Schottky device architecture. To date, little is known about how the influence of composition on AZTSe material properties and the resulting PV performance. In this study, the Ag/Sn ratio is shown to be critical in the controlling grain growth, non-radiative recombination, and the bulk defect structure of the absorber. Insufficient Ag (relative to Zn and Sn) results in small grains, low photoluminescence intensities, and band gap narrowing, possibly due to an increase in the bulk defect density. Additionally, etching the AZTSe films in KCN prior to junction formation is found to be important for achieving reproducible efficiencies. Surface analysis using Auger Nanoprobe Microscopy analysis reveals that a KCN etch can selectively remove potentially harmful Ag-rich secondary phases, therefore improving the MoO_3/AZTSe junction quality. Moreover, grain boundaries in AZTSe are found to be enriched in Sn and O following KCN; the role this oxide plays in surface passivation and junction formation has yet to be determined.

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

    Science.gov (United States)

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

    2017-08-16

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

  11. Photoluminescence study of high energy proton irradiation on Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Bonhyeong [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Lee, June Hyuk [Neutron Science Division, Korea Atomic Energy Research Institute (KAERI), 989-111 Daedeok-daero, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Shin, Donghyeop [Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC 27708 (United States); Ahn, Byung Tae, E-mail: btahn@kaist.ac.kr [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Shin, Byungha, E-mail: byungha@kaist.ac.kr [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

    2016-03-31

    We have studied the effect of proton irradiation on Cu(In,Ga)Se{sub 2} (CIGS) thin films using photoluminescence (PL). We used a 10 MeV proton beam with varying doses from 10{sup 9} to 10{sup 12} cm{sup −2}. Intensity-dependent low temperature PL measurements suggest that the proton irradiation does not create a new defect level but instead changes the number of preexisting defects in the detection range of the PL system. By comparing PL spectra after the proton irradiation with those obtained after thermal annealing under inert gas as well as under hydrogen gas ambient, we find that the irradiation-induced change in the defect structure does not originate from the incorporation of hydrogen but from energetics of the irradiating particles. Electrical resistivity of the proton irradiated CIGS thin films is shown to decrease after the proton irradiation, and this is explained by the reduction of the concentration of compensating donor-like defects, specifically selenium vacancies, based on the PL results. - Highlights: • Photoluminescence study of 10 MeV proton irradiation on CIGS at 10 K. • Irradiation modified population of existing defects without introducing new levels. • Changes in CIGS by 10 MeV irradiation are due to energetics of irradiating protons.

  12. Photo- and Thermo-Induced Changes in Optical Constants and Structure of Thin Films from GeSe2-GeTe-ZnTe System

    Science.gov (United States)

    Petkov, Kiril; Todorov, Rossen; Vassilev, Venceslav; Aljihmani, Lilia

    We examined the condition of preparation of thin films from GeSe2-GeTe-ZnTe system by thermal evaporation and changes in their optical properties after exposure to light and thermal annealing. The results for composition analysis of thin films showed absence of Zn independently of the composition of the bulk glass. By X-ray diffraction (XRD) analysis it was found that a reduction of ZnTe in ZnSe in bulk materials takes of place during the film deposition. A residual from ZnSe was observed in the boat after thin film deposition. Optical constants (refractive index, n and absorption coefficient, α) and thickness, d as well as the optical band gap, Eg, depending of the content of Te in ternary Ge-Se-Te system are determined from specrophotometric measurements in the spectral range 400-2500 nm applying the Swanepoel's envelope method and Tauc's procedure. With the increase of Te content in the layers the absorption edge is shifted to the longer wavelengths, refractive index increases while the optical band gap decreases from 2.02 eV for GeSe2 to 1.26 eV for Ge34Se42Te24. The values of the refractive index decrease after annealing of all composition and Eg increase, respectively. Thin films with composition of Ge27Se47Te9Zn17 and Ge28Se49Te10Zn13 were prepared by co-evaporation of (GeSe2)78(GeTe)22 and Zn from a boat and a crucible and their optical properties, surface morphology and structure were investigated. The existence of a correlation between the optical band gap and the copostion of thin films from the system studied was demonstrated.

  13. Electrical conduction studies of hot wall deposited CdSe{sub x}Te{sub 1-x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Muthukumarasamy, N. [Department of Physics, Coimbatore Institute of Technology, Coimbatore 641014 (India); Balasundaraprabhu, R.; Jayakumar, S.; Kannan, M.D. [Department of Physics, PSG College of Technology, Coimbatore (India)

    2008-08-15

    CdSe{sub x}Te{sub 1-x} thin films of different compositions have been deposited on cleaned glass substrates using the hot wall deposition technique under conditions very close to thermodynamical equilibrium with minimum loss of material. The electrical conductivity of the deposited films has been studied as a function of temperature. All the films showed a transition from phonon-assisted hopping conduction through the impurity band to grain-boundary-limited conduction in the conduction/valence band at temperature around 325 K. The conductivity has been found to vary with composition; it varied from 0.0027 to 0.0198 {omega}{sup -1} cm{sup -1} when x changed from 0 to 1. The activation energies of the films of different compositions determined at 225 and 400 K have been observed to lie in the range 0.0031-0.0098 and 0.0285-0.0750 eV, respectively. The Hall-effect studies carried out on the deposited films revealed that the nature of conductivity (p or n-type) was dependent on film composition; films with composition x=0 and 0.15 have been found to be p-type and the ones with composition x=0.4, 0.6, 0.7, 0.85 and 1 have been observed to exhibit n-type conductivity. The carrier concentration has been determined and is of the order of 10{sup 17} cm{sup -3}. The majority of carrier mobilities of the films have been observed to vary from 0.032 to 0.183 cm{sup 2} V{sup -1} s{sup -1} depending on film composition. The study of the mobility of the charge carriers with temperature in the range of 300-450 K showed that the mobility increased with 3/2 power of temperature indicating that the type of scattering mechanism in the studied temperature range is the ionized impurity scattering mechanism. (author)

  14. Synthesis and characterisation of Cu{sub 2}ZnSnSe{sub 4} thin films prepared via a vacuum evaporation-based route

    Energy Technology Data Exchange (ETDEWEB)

    Volobujeva, O., E-mail: v.olga@staff.ttu.ee; Bereznev, S.; Raudoja, J.; Otto, K.; Pilvet, M.; Mellikov, E.

    2013-05-01

    Different sequentially stacked binary chalcogenide layers (CuSe, ZnSe, and SnSe) deposited by vacuum evaporation onto molybdenum covered soda-lime glass substrates were used as precursors to form Cu{sub 2}ZnSnSe{sub 4} films. The influence of the stacked binary layer sequence, substrate temperature, both the duration and speed of deposition and the post deposition treatment atmosphere on the structural and the morphological parameters of the Cu{sub 2}ZnSnSe{sub 4} thin films was studied. Our results indicate the possibility of replacing the Se{sub 2} selenisation with a thermal treatment in an SnSe{sub 2} atmosphere to avoid the selenisation of the Mo substrate and MoSe{sub 2} formation. This SnSe{sub 2} treatment forms p-type Cu{sub 2}ZnSnSe{sub 4} films with an optical band-gap of 1.14 eV and a solar cell structure with an efficiency of up to 3%. - Highlights: ► Cu{sub 2}ZnSnSe{sub 4} thin films were grown using binary precursors and selenisation. ► Composition and morphology were studied in dependence of selenisation atmosphere. ► The use of SnSe{sub 2} selenisation allows to avoid Mo substrate selenisation. ► The high quality of films is indicated by the value of their E{sub g} = 1.14 eV. ► Cu{sub 2}ZnSnSe{sub 4} thin films were in p-type conductivity and were realized as solar cells.

  15. Investigation of stacked elemental layers for Cu(In,Ga)Se{sub 2} thin film preparation by rapid thermal selenization

    Energy Technology Data Exchange (ETDEWEB)

    Stroth, Christiane; Ohland, Joerg; Mikolajczak, Ulf; Madena, Thomas; Keller, Jan; Parisi, Juergen; Hammer, Maria; Riedel, Ingo [Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg, 26111 Oldenburg (Germany)

    2013-07-01

    Rapid thermal selenization of pure metallic (Cu-In-Ga) or selenium-containing (Cu-In-Ga-Se) precursors is a favorable method to fabricate Cu(In,Ga)Se{sub 2} absorber films for application in thin film solar cells. Because of its upscaling potential and the short process time it is a promising approach for the fabrication of CIGSe photovoltaic modules on industrial scale. As a preliminary work for prospective plasma-enhanced selenization of stacked elemental layers (SEL) the elements copper, indium and gallium were sequentially deposited on molybdenum coated soda-lime glass by thermal evaporation. The stacking order was varied and the precursors were annealed with different heating rates. Morphology, elemental depth distribution and phases of the layers were investigated before and after annealing using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Furthermore the influence of different heating rates on phase transitions during annealing was studied by in-situ X-ray diffraction.

  16. Variation of sulfur content in Cu(In,Ga)(S,Se){sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Knipper, Martin; Knecht, Robin; Riedel, Ingo; Parisi, Juergen [Energy and Semiconductor Research Laboratory, Department of Physics, University of Oldenburg (Germany)

    2011-07-01

    Chalcopyrite thin film solar cells made of the compound semiconductor Cu(In,Ga)(S,Se){sub 2} (CIGSSe) have a strong potential for achieving high efficiencies at low production costs. Volume production of CIGSSe-modules has already started to exploit their favorable attributes such as low cost processing and reasonable module efficiency. In this study we studied industrially produced CIGSSe modules obtained from rapid thermal processing (RTP) for sulfurization. In detail, we investigated the effect of sulfur offer and RTP temperature (500 C to 580 C) on the photoelectric characteristics of small-area solar cells cut from the modules. Current-voltage profiling under standard test conditions revealed a strong influence of the particular process recipe on the open circuit voltage whereas significant variations of the maximum quantum efficiency can be observed. X-ray diffraction was employed to relate these effects to the crystallographic structure of the actual CIGSSe films. Lock-in thermographic imaging was employed to link apparent film inhomogeneities and disruptions to the specific process recipe.

  17. Electrochemical synthesis of nanoplatelets-like CuS0.2Se0.8 thin film for photoluminescence applications

    Directory of Open Access Journals (Sweden)

    Sharma A. K.

    2015-06-01

    Full Text Available Copper sulfide-selenide (CuS0.2Se0.8 thin films were deposited on FTO coated glass substrate (fluorine doped tin oxide and stainless steel substrates using electrodeposition technique. Deposited thin films were characterized using different characterization techniques viz. X-ray diffraction (XRD, scanning electron microscopy (SEM, UV-Vis spectroscopy, photoluminescence spectroscopy and surface wettability. XRD study showed polycrystalline nature with cubic phase of the films. Scanning electron microscopy showed that the surface area of the substrate was covered by the nanoplatelets structure of a thickness of 140 to 150 nm and optical study showed that the direct band gap was ~1.90 eV. Surface wettability showed hydrophobic nature of the CuS0.2Se0.8 thin films.

  18. Effect of the ITO substrate on the growth of Cu(In,Ga)Se{sub 2}, CuGa{sub 3}Se{sub 5}, CuGa{sub 5}Se{sub 8} and CuIn{sub 3}Se{sub 5} thin films by flash evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, E J; Merino, J M; Leon, M [Department of Applied Physics, Universidad Autonoma de Madrid (UAM), Cantoblanco, 28049 Madrid (Spain); Trigo, J F; Guillen, C [Department of Energy, CIEMAT, Avda Complutense, 22, 28040 Madrid (Spain); Ramiro, J, E-mail: josue.friedrich@uam.e [Department of Theory of Signal and Communications, URJC, Campus Fuenlabrada, 122, 28943 Madrid (Spain)

    2009-04-21

    Structural, compositional, electrical and morphological properties of CuIn{sub 1-x}Ga{sub x}Se{sub 2} (x = 0.15, 0.30) and ordered defect compounds (ODC) CuGa{sub 3}Se{sub 5}, CuGa{sub 5}Se{sub 8}, CuIn{sub 3}Se{sub 5} thin films grown by flash evaporation onto soda lime glass substrates (SLG) and ITO/SLG have been studied. Polycrystalline thin films with accentuated preferential orientation in the (1 1 2) plane of the tetragonal structure have been obtained. Annealing in Se atmosphere improves the structural, morphological, electrical and optical properties of the evaporated films, but provokes the formation of a CuIn{sub x}Se{sub y} phase on the surface of the films. Band gap values ranging between 1.01 and 1.21 eV have been obtained for the as-grown CuIn{sub 1-x}Ga{sub x}Se{sub 2} thin films and between 1.09 and 2.01 eV for the CuGa{sub 3}Se{sub 5}, CuGa{sub 5}Se{sub 8} and CuIn{sub 3}Se{sub 5} thin films.

  19. Local current-voltage behaviors of preferentially and randomly textured Cu(In,Ga)Se2 thin films investigated by conductive atomic force microscopy

    International Nuclear Information System (INIS)

    Shin, R.H.; Jo, W.; Kim, D.W.; Yun, Jae Ho; Ahn, S.

    2011-01-01

    Electrical transport properties on polycrystalline Cu(In,Ga)Se 2 (CIGS) (Ga/(In+Ga) ∼35%) thin films were examined by conductive atomic force microscopy. The CIGS thin films with a (112) preferential or random texture were deposited on Mo-coated glass substrates. Triangular pyramidal grain growths were observed in the CIGS thin films preferentially textured to the (112) planes. Current maps of the CIGS surface were acquired with a zero or non-zero external voltage bias. The contrast of the images on the grain boundaries and intragrains displayed the conduction path in the materials. Local current-voltage measurements were performed to evaluate the charge conduction properties of the CIGS thin films. (orig.)

  20. Local current-voltage behaviors of preferentially and randomly textured Cu(In,Ga)Se{sub 2} thin films investigated by conductive atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shin, R.H.; Jo, W. [Ewha Womans University, Department of Physics, Seoul (Korea, Republic of); Kim, D.W. [Ewha Womans University, Department of Physics, Seoul (Korea, Republic of); Ewha Womans University, Department of Chemistry and Nanosciences, Seoul (Korea, Republic of); Yun, Jae Ho; Ahn, S. [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2011-09-15

    Electrical transport properties on polycrystalline Cu(In,Ga)Se{sub 2} (CIGS) (Ga/(In+Ga) {approx}35%) thin films were examined by conductive atomic force microscopy. The CIGS thin films with a (112) preferential or random texture were deposited on Mo-coated glass substrates. Triangular pyramidal grain growths were observed in the CIGS thin films preferentially textured to the (112) planes. Current maps of the CIGS surface were acquired with a zero or non-zero external voltage bias. The contrast of the images on the grain boundaries and intragrains displayed the conduction path in the materials. Local current-voltage measurements were performed to evaluate the charge conduction properties of the CIGS thin films. (orig.)

  1. Characterization of phase change Ga{sub 15}Se{sub 77}Ag{sub 8} chalcogenide thin films by laser-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Alvi, M.A., E-mail: alveema@hotmail.com [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Zulfequar, M. [Department of Physics, Jamia Millia Islamia, New Delhi 110025 (India); Al-Ghamdi, A.A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer Effect of laser-irradiation on structure and optical band gap has been investigated. Black-Right-Pointing-Pointer The amorphous nature has been verified by X-ray diffraction and DSC measurements. Black-Right-Pointing-Pointer Laser-irradiation causes a decrease in optical band gap in Ga{sub 15}Se{sub 77}Ag{sub 8} thin films. Black-Right-Pointing-Pointer The decrease in optical band gap can be interpreted on the basis of amorphous-crystalline phase transformation. Black-Right-Pointing-Pointer Optical absorption data showed that the rules of the non-direct transitions predominate. - Abstract: Phase change Ga{sub 15}Se{sub 77}Ag{sub 8} chalcogenide thin films were prepared by thermal evaporation technique. Thin films were then irradiated by Transverse Electrical Excitation at Atmospheric Pressure (TEA) nitrogen laser for different time intervals. The X-ray structural characterization revealed the amorphous nature of as-prepared films while the laser irradiated films show the polycrystalline nature. Field Emission Scanning Electron Microscope (FESEM) has been used to study the structural changes. The results are discussed in terms of the structural aspects and amorphous to crystalline phase change in Ga{sub 15}Se{sub 77}Ag{sub 8} chalcogenide thin films. The observed changes are associated with the interaction of the incident photon and the lone-pairs electrons which affects the band gap of the Ga{sub 15}Se{sub 77}Ag{sub 8} chalcogenide thin films. The optical constants of these thin films are measured by using the absorption spectra measurements as a function of photon energy in the wavelength region 400-1100 nm. It is found that the optical band gap decreases while the absorption coefficient and extinction coefficient increases with increasing the laser-irradiation time. The decrease in the optical band gap has been explained on the basis of change in nature of films, from amorphous to polycrystalline state. The dc

  2. Investigation of lattice defects and compositional gradients in Cu(In,Ga)Se{sub 2} thin films for solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Jens; Boit, Christian [Department of Semiconductor Devices, Berlin University of Technology, Einsteinufer 19, 10587 Berlin (Germany); Abou-Ras, Daniel; Rissom, Thorsten; Unold, Thomas; Schock, Hans-Werner [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany)

    2011-07-01

    Cu(In,Ga)Se{sub 2} absorber layers used in thin-film solar cells exhibit, when grown in a multi-stage process, compositional gradients of gallium and indium, dependent on process parameters such as the Ga content. The high lateral resolution of transmission electron microscopy (TEM) imaging and energy-dispersive X-ray spectroscopy (EDX) allows the determination of lattice defects and the elemental concentrations at identical sample positions. Cross-sectional TEM samples of ZnO/CdS/Cu(In,Ga)Se{sub 2}/Mo/glass stacks were prepared with varying [Ga]/([In]+[Ga]) ratio in the absorber. The shape of the Ga distribution was measured by means of EDX and differs for the various [Ga]/([In]+[Ga]) ratios. Linear (dislocations) and planar defects (stacking faults, microtwins) were studied by means of TEM bright field and dark field images along the lengths of the Cu(In,Ga)Se{sub 2} layers. Strong Ga compositional gradients were found even within individual grains. It appears that these Ga gradients correlate with the occurrence of dislocation networks in large grains (diameter > 1 {mu}m). We assume that these dislocations compensate for lattice mismatch due to the change in composition in this area of the lattice.

  3. Effects of high-energy proton irradiation on the superconducting properties of Fe(Se,Te) thin films

    Science.gov (United States)

    Sylva, G.; Bellingeri, E.; Ferdeghini, C.; Martinelli, A.; Pallecchi, I.; Pellegrino, L.; Putti, M.; Ghigo, G.; Gozzelino, L.; Torsello, D.; Grimaldi, G.; Leo, A.; Nigro, A.; Braccini, V.

    2018-05-01

    In this paper we explore the effects of 3.5 MeV proton irradiation on Fe(Se,Te) thin films grown on CaF2. In particular, we carry out an experimental investigation with different irradiation fluences up to 7.30 · 1016 cm‑2 and different proton implantation depths, in order to clarify whether and to what extent the critical current is enhanced or suppressed, what are the effects of irradiation on the critical temperature, resistivity, and critical magnetic fields, and finally what is the role played by the substrate in this context. We find that the effect of irradiation on superconducting properties is generally small compared to the case of other iron-based superconductors. The irradiation effect is more evident on the critical current density Jc, while it is minor on the transition temperature Tc, normal state resistivity ρ, and on the upper critical field Hc2 up to the highest fluences explored in this work. In more detail, our analysis shows that when protons implant in the substrate far from the superconducting film, the critical current can be enhanced up to 50% of the pristine value at 7 T and 12 K; meanwhile, there is no appreciable effect on critical temperature and critical fields together with a slight decrease in resistivity. On the contrary, when the implantation layer is closer to the film–substrate interface, both critical current and temperature show a decrease accompanied by an enhancement of the resistivity and lattice strain. This result evidences that possible modifications induced by irradiation in the substrate may affect the superconducting properties of the film via lattice strain. The robustness of the Fe(Se,Te) system to irradiation-induced damage makes it a promising compound for the fabrication of magnets in high-energy accelerators.

  4. Physical characterization of Cu{sub 2}ZnGeSe{sub 4} thin films from annealing of Cu-Zn-Ge precursor layers

    Energy Technology Data Exchange (ETDEWEB)

    Buffière, M., E-mail: buffiere@imec.be [Imec—Partner in Solliance, Leuven (Belgium); Department of Electrical Engineering (ESAT), KU Leuven, Heverlee (Belgium); ElAnzeery, H. [Imec—Partner in Solliance, Leuven (Belgium); KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Microelectronics System Design department, Nile University, Cairo (Egypt); Oueslati, S.; Ben Messaoud, K. [Imec—Partner in Solliance, Leuven (Belgium); KACST-Intel Consortium Center of Excellence in Nano-manufacturing Applications (CENA), Riyadh (Saudi Arabia); Department of Physics, Faculty of Sciences of Tunis, El Manar (Tunisia); Brammertz, G.; Meuris, M. [Imec Division IMOMEC — Partner in Solliance, Diepenbeek (Belgium); Institute for Material Research (IMO) Hasselt University, Diepenbeek (Belgium); Poortmans, J. [Imec—Partner in Solliance, Leuven (Belgium); Department of Electrical Engineering (ESAT), KU Leuven, Heverlee (Belgium)

    2015-05-01

    Cu{sub 2}ZnGeSe{sub 4} (CZGeSe) can be considered as a potential alternative for wide band gap thin film devices. In this work, CZGeSe thin films were deposited on Mo-coated soda lime glass substrates by sequential deposition of sputtered Cu, Zn and e-beam evaporated Ge layers from elemental targets followed by annealing at high temperature using H{sub 2}Se gas. We report on the effect of the precursor stack order and composition and the impact of the annealing temperature on the physical properties of CZGeSe thin films. The optimal layer morphology was obtained when using a Mo/Cu/Zn/Ge precursor stack annealed at 460 °C. We have observed that the formation of secondary phases such as ZnSe can be prevented by tuning the initial composition of the stack, the stack order and the annealing conditions. This synthesis process allows synthesizing CZGeSe absorber with an optical band gap of 1.5 eV. - Highlights: • Cu{sub 2}ZnGeSe{sub 4} (CZGeSe) thin films were deposited using a two-step process. • CZGeSe dense layers were obtained using a Mo/Cu/Zn/Ge precursor annealed at 460 °C. • Formation of ZnSe can be avoided by tuning the composition and order of the initial stack. • P-type CZGeSe absorber with an optical band gap of 1.5 eV was obtained.

  5. Phase transitions in thin films of Sn-Sb-Se system

    International Nuclear Information System (INIS)

    Samsudi Sakrani; Abdalla Belal Adam; Yussof Wahab

    1998-01-01

    The preparation and formation of covalent ternary Sn-Sb-Se system were investigated. A solid state reaction technique was employed whereby the evaporated multilayers of Sn/Se/Sb/Sn reacted chemically at a fixed temperature of 240 o C and were allowed to a room temperature slow-cooling. X-ray diffraction analysis showed that phase changes occurred in the system, with indication of amorphization for the predicted Sn 9 .3Sb 8 .1Se 4 4.9 and Sn 1 3.2Sb 4 3.4Se 4 3.4 compositions. These enabled the preliminary topological phase transitions of Sn-Sb-Se system according to the Gibb's triangle in which the areas of crystalline-amorphous were located. (Author)

  6. Thin films

    International Nuclear Information System (INIS)

    Strongin, M.; Miller, D.L.

    1976-01-01

    This article reviews the phenomena that occur in films from the point of view of a solid state physicist. Films form the basis for many established and developing technologies. Metal layers have always been important for optical coatings and as protective coatings. In the most sophisticated cases, films and their interaction on silicon surfaces form the basis of modern electronic technology. Films of silicon, GaAs and composites of these materials promise to lead to practical photovoltaic devices

  7. Surfaces of colloidal PbSe nanocrystals probed by thin-film positron annihilation spectroscopy

    Directory of Open Access Journals (Sweden)

    L. Chai

    2013-08-01

    Full Text Available Positron annihilation lifetime spectroscopy and positron-electron momentum density (PEMD studies on multilayers of PbSe nanocrystals (NCs, supported by transmission electron microscopy, show that positrons are strongly trapped at NC surfaces, where they provide insight into the surface composition and electronic structure of PbSe NCs. Our analysis indicates abundant annihilation of positrons with Se electrons at the NC surfaces and with O electrons of the oleic ligands bound to Pb ad-atoms at the NC surfaces, which demonstrates that positrons can be used as a sensitive probe to investigate the surface physics and chemistry of nanocrystals inside multilayers. Ab initio electronic structure calculations provide detailed insight in the valence and semi-core electron contributions to the positron-electron momentum density of PbSe. Both lifetime and PEMD are found to correlate with changes in the particle morphology characteristic of partial ligand removal.

  8. Depth-Profiling Electronic and Structural Properties of Cu(In,Ga)(S,Se)2 Thin-Film Solar Cell.

    Science.gov (United States)

    Chiang, Ching-Yu; Hsiao, Sheng-Wei; Wu, Pin-Jiun; Yang, Chu-Shou; Chen, Chia-Hao; Chou, Wu-Ching

    2016-09-14

    Utilizing a scanning photoelectron microscope (SPEM) and grazing-incidence X-ray powder diffraction (GIXRD), we studied the electronic band structure and the crystalline properties of the pentanary Cu(In,Ga)(S,Se)2 (CIGSSe) thin-film solar cell as a function of sample depth on measuring the thickness-gradient sample. A novel approach is proposed for studying the depth-dependent information on thin films, which can provide a gradient thickness and a wide cross-section of the sample by polishing process. The results exhibit that the CIGSSe absorber layer possesses four distinct stoichiometries. The growth mechanism of this distinctive compositional distribution formed by a two-stage process is described according to the thermodynamic reaction and the manufacturing process. On the basis of the depth-profiling results, the gradient profiles of the conduction and valence bands were constructed to elucidate the performance of the electrical properties (in this case, Voc = 620 mV, Jsc = 34.6 mA/cm(2), and η = 14.04%); the valence-band maxima (VBM) measured with a SPEM in the spectroscopic mode coincide with this band-structure model, except for a lowering of the VBM observed in the surface region of the absorber layer due to the ordered defect compound (ODC). In addition, the depth-dependent texturing X-ray diffraction pattern presents the crystalline quality and the residual stress for each depth of a thin-film device. We find that the randomly oriented grains in the bottom region of the absorber layer and the different residual stress between the underlying Mo and the absorber interface, which can deteriorate the electrical performance due to peeling-off effect. An anion interstitial defect can be observed on comparing the anion concentration of the elemental distribution with crystalline composition; a few excess sulfur atoms insert in interstitial sites at the front side of the absorber layer, whereas the interstitial selenium atoms insert at the back side.

  9. Improved growth of solution-deposited thin films on polycrystalline Cu(In,Ga)Se{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Witte, Wolfram; Hariskos, Dimitrios [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), 70565, Stuttgart (Germany); Abou-Ras, Daniel [Helmholtz-Zentrum Berlin fuer Materialien und Energie, 14109, Berlin (Germany)

    2016-04-15

    CdS and Zn(O,S) grown by chemical bath deposition (CBD) are well established buffer materials for Cu(In,Ga)Se{sub 2} (CIGS) solar cells. As recently reported, a non-contiguous coverage of CBD buffers on CIGS grains with {112} surfaces can be detected, which was explained in terms of low surface energies of the {112} facets, leading to deteriorated wetting of the chemical solution on the CIGS surface. In the present contribution, we report on the effect of air annealing of CIGS thin films prior to the CBD of CdS and Zn(O,S) layers. In contrast to the growth on the as-grown CIGS layers, these buffer lay- ers grow densely on the annealed CIGS layer, even on grains with {112} surfaces. We explain the different growth behavior by increased surface energies of CIGS grains due to the annealing step, i.e., due to oxidation of the CIGS surface. Reference solar cells were processed and completed by i-ZnO/ZnO:Al layers for CdS and by (Zn,Mg)O/ZnO:Al for Zn(O,S) buffers. For solar cells with both, CdS and Zn(O,S) buffers, air-annealed CIGS films with improved buffer coverage resulted in higher power-conversion efficiencies, as compared with the devices containing as-grown CIGS layers. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Structure and properties of ZnSxSe1-x thin films deposited by thermal evaporation of ZnS and ZnSe powder mixtures

    Science.gov (United States)

    Valeev, R. G.; Romanov, E. A.; Vorobiev, V. L.; Mukhgalin, V. V.; Kriventsov, V. V.; Chukavin, A. I.; Robouch, B. V.

    2015-02-01

    Interest to ZnSxSe1-x alloys is due to their band-gap tunability varying S and Se content. Films of ZnSxSe1-x were grown evaporating ZnS and ZnSe powder mixtures onto SiO2, NaCl, Si and ITO substrates using an original low-cost method. X-ray diffraction patterns and Raman spectroscopy, show that the lattice structure of these films is cubic ZnSe-like, as S atoms replace Se and film compositions have their initial S/Se ratio. Optical absorption spectra show that band gap values increase from 2.25 to 3 eV as x increases, in agreement with the literature. Because S atomic radii are smaller than Se, EXAFS spectra confirm that bond distances and Se coordination numbers decrease as the Se content decreases. The strong deviation from linearity of ZnSe coordination numbers in the ZnSxSe1-x indicate that within this ordered crystal structure strong site occupation preferences occur in the distribution of Se and S ions. The behavior is quantitatively confirmed by the strong deviation from the random Bernoulli distribution of the three sight occupation preference coefficients of the strained tetrahedron model. Actually, the ternary ZnSxSe1-x system is a bi-binary (ZnS+ZnSe) alloy with evanescent formation of ternary configurations throughout the x-range.

  11. A study on molybdenum sulphoselenide (MoSxSe2−x, 0 ≤ x ≤ 2) thin films: Growth from solution and its properties

    International Nuclear Information System (INIS)

    Anand, T. Joseph Sahaya; Shariza, S.

    2012-01-01

    Highlights: ► Effect of deposition time on the properties of molybdenum chalcogenide thin films. ► First time to compare the study of binary and ternary molybdenum chalcogenides. ► No previous report on ternary molybdenum sulphoselenide by electrodeposition. ► Semiconducting parameters by CV analysis promising to be good solar cell material. - Abstract: Thin films of molybdenum sulphoselenide, MoS x Se 2−x , (0 ≤ x ≤ 2) have been electrosynthesized on indium-tin-oxide (ITO)-coated glass and stainless steel substrates. The films were characterized for their structural, morphological and compositional characteristics. Their optical and semiconducting parameters were also analysed in order to determine the suitability of the thin films for photoelectrochemical (PEC)/solar cell applications. Structural analysis via X-ray diffraction (XRD) analysis reveals that the films are polycrystalline in nature. Scanning electron microscope (SEM) studies reveals the films were adherent to the substrate with uniform in nature which also confirmed by Transmission electron microscope (TEM). Compositional analysis via energy dispersive X-ray (EDX) technique confirms the presence of Mo, S and Se elements in the films. The optical studies show that the films are of direct bandgap. Results on the semiconductor parameters analysis of the films showed that the nature of the Mott–Schottky plots indicates that the films obtained are of n-type material. For all films, the semiconductor parameter values come in the better range of other transition metal chalcogenides which has proven that MoSSe thin films are capable as solar/PEC cell materials.

  12. Reduced recombination in a surface-sulfurized Cu(InGa)Se2 thin-film solar cell

    Science.gov (United States)

    Kim, Shinho; Nishinaga, Jiro; Kamikawa, Yukiko; Ishizuka, Shogo; Nagai, Takehiko; Koida, Takashi; Tampo, Hitoshi; Shibata, Hajime; Matsubara, Koji; Niki, Shigeru

    2018-05-01

    This study demonstrates surface sulfurization effects on Cu(InGa)Se2 (CIGSe) thin-film solar cells with a single back-graded band gap. Single back-graded CIGSe thin films were prepared via a three-stage process in a high-vacuum molecular beam epitaxial growth chamber and were subsequently annealed in a tube furnace under environmental conditions with H2S gas. After sulfurization, an ∼80- to ∼100-nm-thick CuIn(SSe)2 layer with significantly small Ga contents (CISSe:Ga) was formed on the CIGSe layer. The newly formed CISSe:Ga layer exhibited graded S contents from surface to bulk, thus resulting in a front-graded band gap. In addition, CISSe:Ga was covered with S-enriched CISSe region that was extended from the surface to a depth of a few nm and was depleted of Ga. A device with the sulfurized CIGSe showed reduced recombination at the buffer–absorber interface, in space-charge region and in bulk. Consequently, the open circuit voltage increased from 0.58 V (in the non-sulfurized case) to 0.66 V, and the conversion efficiency improved from 15.5 to 19.4%. This large improvement is caused by the front graded band gap at the surface and the hole-blocking barrier, which suppress recombination at the CdS/CISSe:Ga interface. In addition, sulfurization followed by KF post-deposition treatment (PDT) increased the efficiency to 20.1%. Compared to the untreated sulfurized device, the KF-PDT device delivered an increased carrier lifetime and reduced the recombination in bulk probably because the defects were passivated by the K, which penetrated into the bulk region.

  13. Ecofriendly and Nonvacuum Electrostatic Spray-Assisted Vapor Deposition of Cu(In,Ga)(S,Se)2 Thin Film Solar Cells.

    Science.gov (United States)

    Hossain, Md Anower; Wang, Mingqing; Choy, Kwang-Leong

    2015-10-14

    Chalcopyrite Cu(In,Ga)(S,Se)2 (CIGSSe) thin films have been deposited by a novel, nonvacuum, and cost-effective electrostatic spray-assisted vapor deposition (ESAVD) method. The generation of a fine aerosol of precursor solution, and their controlled deposition onto a molybdenum substrate, results in adherent, dense, and uniform Cu(In,Ga)S2 (CIGS) films. This is an essential tool to keep the interfacial area of thin film solar cells to a minimum value for efficient charge separation as it helps to achieve the desired surface smoothness uniformity for subsequent cadmium sulfide and window layer deposition. This nonvacuum aerosol based approach for making the CIGSSe film uses environmentally benign precursor solution, and it is cheaper for producing solar cells than that of the vacuum-based thin film solar technology. An optimized CIGSSe thin film solar cell with a device configuration of molybdenum-coated soda-lime glass substrate/CIGSSe/CdS/i-ZnO/AZO shows the photovoltaic (j-V) characteristics of Voc=0.518 V, jsc=28.79 mA cm(-2), fill factor=64.02%, and a promising power conversion efficiency of η=9.55% under simulated AM 1.5 100 mW cm(-2) illuminations, without the use of an antireflection layer. This demonstrates the potential of ESAVD deposition as a promising alternative approach for making thin film CIGSSe solar cells at a lower cost.

  14. Indium selenide (In2Se3) thin film for phase-change memory

    International Nuclear Information System (INIS)

    Lee, Heon; Kang, Dae-Hwan; Tran, Lung

    2005-01-01

    A cross-point type phase-change random access memory (PRAM) device without an access transistor is successfully fabricated with the In 2 Se 3 -phase-change resistor, which has much higher electrical resistivity than Ge 2 Sb 2 Te 5 and of which electric resistivity can be varied by the factor of 10 5 times, related with the degree of crystallization. Due to its higher electrical resistivity, the switching power can be delivered more effectively. Since In 2 Se 3 is single-phase binary compound, the device failure related to phase decomposition can be avoided. Since the volume of phase change is very limited, and the heating duration is only for few tens of nanoseconds to 10 μs, the transition of In 2 Se 3 -phase-change material is done under very far from its thermodynamic equilibrium condition, and thus, formation of the secondary phases or different crystalline phases was not observed. The static mode switching (dc test) is tested for the 5 μm-sized In 2 Se 3 PRAM device. In the first sweep, the as-grown amorphous In 2 Se 3 resistor showed the high resistance state at low voltage region. However, when it reached the threshold voltage, the electrical resistance of the device was drastically reduced through the formation of an electrically conducting path. The pulsed mode switching of the 5 μm-sized In 2 Se 3 PRAM device shows that the reset (crystalline → amorphous) of the device was done with a 70 ns-3.1 V pulse and the set (amorphous → crystalline) of the device was done with a 10 μs-1.2 V pulse. As high as 100 of switching dynamic range (ratio of R high to R low ) was observed

  15. Uniform Thin Films of CdSe and CdSe(ZnS) Core(shell) Quantum Dots by Sol-Gel Assembly: Enabling Photoelectrochemical Characterization and Electronic Applications

    Science.gov (United States)

    Korala, Lasantha; Wang, Zhijie; Liu, Yi; Maldonado, Stephen; Brock, Stephanie L.

    2013-01-01

    Optoelectronic properties of quantum dot (QD) films are limited by (1) poor interfacial chemistry and (2) non-radiative recombination due to surface traps. To address these performance issues, sol-gel methods are applied to fabricate thin films of CdSe and core(shell) CdSe(ZnS) QDs. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) imaging with chemical analysis confirms that the surface of the QDs in the sol-gel thin films are chalcogen-rich, consistent with an oxidative-induced gelation mechanism in which connectivity is achieved by formation of dichalcogenide covalent linkages between particles. The ligand removal and assembly process is probed by thermogravimetric, spectroscopic and microscopic studies. Further enhancement of inter-particle coupling via mild thermal annealing, which removes residual ligands and reinforces QD connectivity, results in QD sol-gel thin films with superior charge transport properties, as shown by a dramatic enhancement of electrochemical photocurrent under white light illumination relative to thin films composed of ligand-capped QDs. A more than 2-fold enhancement in photocurrent, and a further increase in photovoltage can be achieved by passivation of surface defects via overcoating with a thin ZnS shell. The ability to tune interfacial and surface characteristics for the optimization of photophysical properties suggests that the sol-gel approach may enable formation of QD thin films suitable for a range of optoelectronic applications. PMID:23350924

  16. Review on Alkali Element Doping in Cu(In,GaSe2 Thin Films and Solar Cells

    Directory of Open Access Journals (Sweden)

    Yun Sun

    2017-08-01

    Full Text Available This paper reviews the development history of alkali element doping on Cu(In,GaSe2 (CIGS solar cells and summarizes important achievements that have been made in this field. The influences of incorporation strategies on CIGS absorbers and device performances are also reviewed. By analyzing CIGS surface structure and electronic property variation induced by alkali fluoride (NaF and KF post-deposition treatment (PDT, we discuss and interpret the following issues: ① The delamination of CIGS thin films induced by Na incorporation facilitates CuInSe2 formation and inhibits Ga during low-temperature co-evaporation processes. ② The mechanisms of carrier density increase due to defect passivation by Na at grain boundaries and the surface. ③ A thinner buffer layer improves the short-circuit current without open-circuit voltage loss. This is attributed not only to better buffer layer coverage in the early stage of the chemical bath deposition process, but also to higher donor defect (CdCu+ density, which is transferred from the acceptor defect (VCu− and strengthens the buried homojunction. ④ The KF-PDT-induced lower valence band maximum at the absorber surface reduces the recombination at the absorber/buffer interface, which improves the open-circuit voltage and the fill factor of solar cells.

  17. Interfacial passivation of CdS layer to CdSe quantum dots-sensitized electrodeposited ZnO nanowire thin films

    International Nuclear Information System (INIS)

    Zhang, Jingbo; Sun, Chuanzhen; Bai, Shouli; Luo, Ruixian; Chen, Aifan; Sun, Lina; Lin, Yuan

    2013-01-01

    ZnO porous thin films with nanowire structure were deposited by the one-step electrochemical deposition method. And a CdS layer was coated on the as-deposited ZnO nanowire thin films by successive ionic layer adsorption and reaction (SILAR) method to passivate surface states. Then the films were further sensitized by CdSe quantum dots (QDs) to serve as a photoanode for fabricating quantum dots-sensitized solar cells (QDSSCs). The effect of the CdS interfacial passivation layer on the performance of the QDSSCs was systematically investigated by varying the SILAR cycle number and heating the passivation layer. The amorphous CdS layer with an optimized thickness can effectively suppress the recombination of the injected electrons with holes on QDs and the redox electrolyte. The newly formed CdS layer on the surface of the ZnO nanowire thin film obviously prolongs the electron lifetime in the passivated ZnO nanoporous thin film because of the lower surface trap density in the ZnO nanowires after CdS deposition, which is favorable to the higher short-circuit photocurrent density (J sc ). For the CdSe QDs-sensitized ZnO nanoporous thin film with the interfacial passivation layer, the J sc and conversion efficiency can reach a maximum of 8.36 mA cm −2 and 2.36%, respectively. The conversion efficiency was improved by 83.47% compared with that of the cell based on the CdSe QDs-sensitized ZnO nanoporous thin film without CdS interfacial passivation (0.39%)

  18. Effect of selenization time on the structural and morphological properties of Cu(In,Ga)Se2 thin films absorber layers using two step growth process

    Science.gov (United States)

    Korir, Peter C.; Dejene, Francis B.

    2018-04-01

    In this work two step growth process was used to prepare Cu(In, Ga)Se2 thin film for solar cell applications. The first step involves deposition of Cu-In-Ga precursor films followed by the selenization process under vacuum using elemental selenium vapor to form Cu(In,Ga)Se2 film. The growth process was done at a fixed temperature of 515 °C for 45, 60 and 90 min to control film thickness and gallium incorporation into the absorber layer film. The X-ray diffraction (XRD) pattern confirms single-phase Cu(In,Ga)Se2 film for all the three samples and no secondary phases were observed. A shift in the diffraction peaks to higher 2θ (2 theta) values is observed for the thin films compared to that of pure CuInSe2. The surface morphology of the resulting film grown for 60 min was characterized by the presence of uniform large grain size particles, which are typical for device quality material. Photoluminescence spectra show the shifting of emission peaks to higher energies for longer duration of selenization attributed to the incorporation of more gallium into the CuInSe2 crystal structure. Electron probe microanalysis (EPMA) revealed a uniform distribution of the elements through the surface of the film. The elemental ratio of Cu/(In + Ga) and Se/Cu + In + Ga strongly depends on the selenization time. The Cu/In + Ga ratio for the 60 min film is 0.88 which is in the range of the values (0.75-0.98) for best solar cell device performances.

  19. Polycrystalline thin-film TiO2/Se solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Nakada, T; Kunioka, A

    1985-07-01

    A new type of selenium solar cell with a titanium dioxide (TiO2)/Se heterojunction has been fabricated by low-cost process.An efficiency of 5.01 percent under AM 1.5 illumination (100 mW/sq cm) has been achieved without antireflection coatings. The corresponding short-circuit current density, open-circuit voltage, and fill factor are 10.8 mA/sq cm, 0.884 V, and 0.525, respectively.The efficiency is the highest among Se-based solar cells reported to date. These cells also have extremely high spectral response at short wavelengths, resulting in efficiencies of 11-13 percent under fluorescent light (500 lux). 10 references.

  20. In{sub 6}Se{sub 7} thin films by heating thermally evaporated indium and chemical bath deposited selenium multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Ornelas, R.E.; Avellaneda, D. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon-66450 (Mexico); Shaji, S. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon-66450 (Mexico); Universidad Autonoma de Nuevo Leon-CIIDIT, Apodaca, N.L (Mexico); Castillo, G.A.; Roy, T.K. Das [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon-66450 (Mexico); Krishnan, B., E-mail: kbindu_k@yahoo.com [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon-66450 (Mexico); Universidad Autonoma de Nuevo Leon-CIIDIT, Apodaca, N.L (Mexico)

    2012-05-15

    Indium selenide (In{sub 6}Se{sub 7}) thin films were prepared via selenization of thermally evaporated indium thin films by dipping in sodium selenosulphate solution followed by annealing in nitrogen atmosphere. First, indium was thermally evaporated on glass substrate. Then, the indium coated glass substrates were dipped in a solution containing 80 ml 0.125 M sodium selenosulphate and 1.5 ml dilute acetic acid (25%) for 5 min. Glass/In-Se layers were annealed at 200-400 Degree-Sign C in nitrogen atmosphere (0.1 Torr) for 30 min. X-ray diffraction studies showed the formation of monoclinic In{sub 6}Se{sub 7}. Morphology of the thin films formed at different conditions was analyzed using Scanning electron microscopy. The elemental analysis was done using Energy dispersive X-ray detection. Electrical conductivity under dark and illumination conditions was evaluated. Optical band gap was computed using transmittance and reflectance spectra. The band gap value was in the range 1.8-2.6 eV corresponding to a direct allowed transition. We studied the effect of indium layer thickness and selenium deposition time on the structure, electrical and optical properties of In{sub 6}Se{sub 7} thin films.

  1. Structural and electrical properties of co-evaporated Cu(In,Ga)Se{sub 2} thin films with varied Cu contents

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Young; Kim, Girim; Kim, Jongwan; Park, Jae Hwan; Lim, Donggun, E-mail: dglim@ut.ac.kr

    2013-11-01

    Cu(In,Ga)Se{sub 2} (CIGS) thin films were fabricated with varying Cu contents. Cu/(Ga + In) ratios were varied between 0.4 and 1.02. Solar cells were then fabricated by co-evaporation using the CIGS layers as absorbers. The influences of Cu content on the cells' structural, optical and electrical properties were studied. The CIGS thin films were characterized by X-ray diffractometer, scanning electron microscopy, energy-dispersive spectroscopy, four-point probe measurement and Hall measurement. Grain size in the films increased with increasing Cu content. At a Cu/(Ga + In) ratio of 0.86, the (220/204) peak was stronger than the (112) peak and carrier concentration was 1.49 × 10{sup 16} cm{sup −3}. Optimizing the Cu content resulted in a CIGS solar cell with an efficiency of 16.5%. - Highlights: • Improvement of technique to form Cu(In,Ga)Se{sub 2} (CIGS) film by co-evaporation method • Cu/(In + Ga) ratio to improve the efficiency for CIGS thin film solar cell • Cu content effects have been analyzed. • Optimum condition of CIGS layer as an absorber of thin film solar cells.

  2. Comparison of Cu(In, Ga)Se{sub 2} thin films deposited on different preferred oriented Mo back contact by RF sputtering from a quaternary target

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Jing [Sichuan University, College of Materials Science and Engineering, Chengdu (China); Solar Energy Research Institute, Yunnan Normal University, Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Kunming (China); Peng, Lianqin; Chen, Jinwei; Wang, Gang; Wang, Xueqin; Kang, Hong; Wang, Ruilin [Sichuan University, College of Materials Science and Engineering, Chengdu (China)

    2014-09-15

    The Cu(In, Ga)Se{sub 2} (CIGS) thin films were deposited on bare glass and DC sputtered preferential oriented Mo-coated glass by RF sputtering from a single quaternary target. The structural and morphological properties of the films were characterized by X-ray diffraction (XRD), Raman spectroscope, energy dispersive X-ray spectrometer (EDS) and atomic force microscope (AFM). Preferred orientation of the Mo back contact was tuned between (110) and (211) plane by controlling the thickness. All the deposited CIGS thin films show (112) preferred oriented chalcopyrite structures. The films prepared on Mo-coated glass show higher quality crystallinity, better stoichiometry composition and more smooth surface morphology. Especially, the film on (211) oriented Mo-coated glass with the best integrated performance is expected to be a candidate absorber for high-efficiency CIGS solar cell device. (orig.)

  3. Effect of Ge Addition on the Optical Band Gap and Refractive Index of Thermally Evaporated As2Se3 Thin Films

    Directory of Open Access Journals (Sweden)

    Pankaj Sharma

    2008-01-01

    Full Text Available The present paper reports the effect of Ge addition on the optical band gap and refractive index of As2Se3 thin films. Thin films of As2Se3 and (As2Se390Ge10 were prepared by thermal evaporation technique at base pressure 10−4 Pa. Optical band gap and refractive index were calculated by analyzing the transmission spectrum in the spectral range 400–1500 nm. The optical band gap decreases while the refractive index increases with the addition of Ge to As2Se3. The decrease of optical band gap has been explained on the basis of density of states; and the increase in refractive index has been explained on the basis increase in disorder in the system.

  4. Structural properties of In2Se3 precursor layers deposited by spray pyrolysis and physical vapor deposition for CuInSe2 thin-film solar cell applications

    International Nuclear Information System (INIS)

    Reyes-Figueroa, P.; Painchaud, T.; Lepetit, T.; Harel, S.; Arzel, L.; Yi, Junsin; Barreau, N.; Velumani, S.

    2015-01-01

    The structural properties of In 2 Se 3 precursor thin films grown by chemical spray pyrolysis (CSP) and physical vapor deposition (PVD) methods were compared. This is to investigate the feasibility to substitute PVD process of CuInSe 2 (CISe) films by CSP films as precursor layer, thus decreasing the production cost by increasing material-utilization efficiency. Both films of 1 μm thickness were deposited at the same substrate temperature of 380 °C. X-ray diffraction and Raman spectra confirm the formation of γ-In 2 Se 3 crystalline phase for both films. The PVD and CSP films exhibited (110) and (006) preferred orientations, respectively. The PVD films showed a smaller full width at half maximum value (0.09°) compared with CSP layers (0.1°). Films with the same crystalline phase but with different orientations are normally used in the preparation of high quality CISe films by 3-stage process. Scanning electron microscope cross-section images showed an important difference in grain size with well-defined larger grains of size 1–2 μm in the PVD films as compared to CSP layers (600 nm). Another important characteristic that differentiates the two precursor films is the oxygen contamination. X-ray photoelectron spectroscopy showed the presence of oxygen in CSP films. The oxygen atoms could be bonded to indium by replacing Se vacancies, which are formed during CSP deposition. Taking account of the obtained results, such CSP films can be used as precursor layer in a PVD process in order to produce CISe absorber films. - Highlights: • To find the intricacies involved in spray pyrolysis (CSP) and physical vapor (PVD) deposition. • Comparison of CSP and PVD film formations — especially in structural properties. • Feasibility to substitute CSP (cheaper) films for PVD in the manufacturing process. • Decreasing the global production cost of Cu(In,Ga)Se 2 devices in the 3-stage process

  5. CIGS thin films, solar cells, and submodules fabricated using a rf-plasma cracked Se-radical beam source

    International Nuclear Information System (INIS)

    Ishizuka, Shogo; Yamada, Akimasa; Shibata, Hajime; Fons, Paul; Niki, Shigeru

    2011-01-01

    Coevaporated Cu(In,Ga)Se 2 (CIGS) film growth using a rf-plasma cracked Se-radical beam (R-Se) source leads to a significant reduction in the amount of raw Se source material wasted during growth and exhibits unique film properties such as highly dense, smooth surfaces and large grain size. R-Se grown CIGS solar cells also show concomitant unique properties different from conventional evaporative Se (E-Se) source grown CIGS cells. In the present work, the impact of modified surfaces, interfaces, and bulk crystal properties of R-Se grown CIGS films on the solar cell performance was studied. When a R-Se source was used, Na diffusion into CIGS layers was enhanced while a remarkable diffusion of elemental Ga and Se into Mo back contact layers was observed. Improvements in the bulk crystal quality as manifested by large grain size and increased Na concentration with the use of a R-Se source is expected to be effective to improve photovoltaic performance. Using a R-Se source for the growth of CIGS absorber layers at a relatively low growth temperature, we have successfully demonstrated a monolithically integrated submodule efficiency of 15.0% (17 cells, aperture area of 76.5 cm 2 ) on 0.25-mm thick soda-lime glass substrates.

  6. 11.3% efficiency Cu(In,Ga)(S,Se)2 thin film solar cells via drop-on-demand inkjet printing

    OpenAIRE

    Lin, Xianzhong; Klenk, Reiner; Wang, Lan; Köhler, Tristan; Albert, Jürgen; Fiechter, Sebastian; Ennaoui, Ahmed; Lux-Steiner, Martha

    2017-01-01

    Although Cu(In,Ga)(S,Se)2 (CIGSe) based thin film solar cells have reached efficiencies exceeding 22% based on vacuum processed CIGSSe absorbers, the supply of indium and gallium might become an issue if CIGSSe thin-film solar cells are produced in very large volumes. It is therefore mandatory to reduce the wastage of indium and gallium during the fabrication process. In this work, we report on a highly efficient precursor utilization, and a vacuum-free, and scalable route to the deposition o...

  7. Ionization effects on Cu(In, Ga)Se{sub 2} thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kawakita, Shirou; Imaizumi, Mitsuru [Japan Aerospace Exploration Agency, 2-1-1 Sengen, Tsukuba, Ibaraki 305-0031 (Japan); Ishizuka, Shogo; Shibata, Hajime [Institute of National Advanced Industrial Science and Technology, 1-1 Umezono, Tsukuba 305-8568 (Japan); Okuda, Shuichi [Osaka Prefecture University, 1-2 Gakuenmachi, Sakai 599-8570 (Japan)

    2017-06-15

    Cu (In, Ga) Se{sub 2} (CIGS) solar cells were irradiated with 60, 100, and 250 keV electrons to reveal the characteristics of radiation induced defects. Electrons with less than 200 keV energy cannot generate any displacement defects in CIGS materials. In addition, a low amount of the electrons can improve the roll-over behavior in current-voltage characteristics of CIGS solar cells. However, the deterioration of the electrical performance in CIGS solar cells irradiated with a high amount of electrons was observed. The deterioration rate on the cells irradiated with lower-energy electrons was higher than that induced by electrons with higher-energy. The degradation curve of J{sub SC} based on the ionizing dose estimated from the ionizing energy loss model does not depend on the energy of electrons. Therefore, it implies that the electrons can degrade CIGS solar cells due to the ionization effect. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Potassium-induced surface modification of Cu(In,Ga)Se2 thin films for high-efficiency solar cells.

    Science.gov (United States)

    Chirilă, Adrian; Reinhard, Patrick; Pianezzi, Fabian; Bloesch, Patrick; Uhl, Alexander R; Fella, Carolin; Kranz, Lukas; Keller, Debora; Gretener, Christina; Hagendorfer, Harald; Jaeger, Dominik; Erni, Rolf; Nishiwaki, Shiro; Buecheler, Stephan; Tiwari, Ayodhya N

    2013-12-01

    Thin-film photovoltaic devices based on chalcopyrite Cu(In,Ga)Se2 (CIGS) absorber layers show excellent light-to-power conversion efficiencies exceeding 20%. This high performance level requires a small amount of alkaline metals incorporated into the CIGS layer, naturally provided by soda lime glass substrates used for processing of champion devices. The use of flexible substrates requires distinct incorporation of the alkaline metals, and so far mainly Na was believed to be the most favourable element, whereas other alkaline metals have resulted in significantly inferior device performance. Here we present a new sequential post-deposition treatment of the CIGS layer with sodium and potassium fluoride that enables fabrication of flexible photovoltaic devices with a remarkable conversion efficiency due to modified interface properties and mitigation of optical losses in the CdS buffer layer. The described treatment leads to a significant depletion of Cu and Ga concentrations in the CIGS near-surface region and enables a significant thickness reduction of the CdS buffer layer without the commonly observed losses in photovoltaic parameters. Ion exchange processes, well known in other research areas, are proposed as underlying mechanisms responsible for the changes in chemical composition of the deposited CIGS layer and interface properties of the heterojunction.

  9. Investigation of recombinatoric loss mechanisms in Cu(In,Ga)Se{sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Knecht, Robin; Klinkert, Torben; Parisi, Juergen; Riedel, Ingo [Thin Film Photovoltaics, Energy- and Semiconductor Research Laboratory, University of Oldenburg, D-26111 Oldenburg (Germany); Schaeffler, Raymund; Dimmler, Bernhard [Wuerth Solar GmbH and Co. KG, Alfred-Leikam-Strasse 25, D-74523 Schwaebisch-Hall (Germany)

    2011-07-01

    Today solar cells based on the compound semiconductor Cu(In,Ga)Se{sub 2} (CIGSe) present the highest lab scale efficiency among all thin-film technologies. The performance of elementary cells in photovoltaic modules might however be different due to thicker conductive ZnO:Al window layers, missing anti-reflection coating and occasionally less defined absorber formation on large scales. One approach to improve the elementary cell efficiency is to fine-tune the absorber composition and the in-depth band gap grading. In this work we investigated CIGSe samples with varied absorber composition in order to quantify the minority carrier collection efficiency (CE). CE is directly related to the electron diffusion length L{sub D,n} and the characteristics of the space charge region (SCR). L{sub D,n} was deduced by relating the inverse internal quantum efficiency to the penetration depth of incident photons and the SCR characteristics were obtained from capacitance-profiling of the samples. Based on these results we discuss the different photovoltaic performance observed for samples with varied CIGSe absorber composition.

  10. Correcting for interference effects in the photoluminescence of Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wolter, Max Hilaire; Siebentritt, Susanne [Laboratory for Photovoltaics, Physics and Materials Science Research Unit, University of Luxembourg, 4422 Belvaux (Luxembourg); Bissig, Benjamin; Reinhard, Patrick; Buecheler, Stephan [Laboratory for Thin Films and Photovoltaics, Empa - Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstr. 129, 8600 Duebendorf (Switzerland); Jackson, Philip [Zentrum fuer Sonnenenergie-und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), 70565 Stuttgart (Germany)

    2017-06-15

    Photoluminescence (PL) measurements are performed on high-quality Cu(In,Ga)Se{sub 2} (CIGS) thin films with the intention of investigating their electronic structure. Due to the nature of the CIGS absorbers, notably their smooth surface and a graded band gap, the measured PL spectra are distorted by interference effects, limiting thus the information that one can gain. Here we show that, by varying the entrance angle of the laser light and the detection angle of the emitted PL, we are able to correct for interference effects. As a result, we receive interference-free PL spectra that enable us to determine quantities such as band gap energies and quasi-Fermi level splittings (QFLS). Furthermore, we show that it is possible to measure the QFLS even without correcting for interference effects and we compare the QFLS to the open circuit voltage for a particular sample. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Rubidium distribution at atomic scale in high efficient Cu(In,Ga)Se2 thin-film solar cells

    Science.gov (United States)

    Vilalta-Clemente, Arantxa; Raghuwanshi, Mohit; Duguay, Sébastien; Castro, Celia; Cadel, Emmanuel; Pareige, Philippe; Jackson, Philip; Wuerz, Roland; Hariskos, Dimitrios; Witte, Wolfram

    2018-03-01

    The introduction of a rubidium fluoride post deposition treatment (RbF-PDT) for Cu(In,Ga)Se2 (CIGS) absorber layers has led to a record efficiency up to 22.6% for thin-film solar cell technology. In the present work, high efficiency CIGS samples with RbF-PDT have been investigated by atom probe tomography (APT) to reveal the atomic distribution of all alkali elements present in CIGS layers and compared with non-treated samples. A Scanning Electron Microscopy Dual beam station (Focused Ion Beam-Gas Injection System) as well as Transmission Kikuchi diffraction is used for atom probe sample preparation and localization of the grain boundaries (GBs) in the area of interest. The analysis of the 3D atomic scale APT reconstructions of CIGS samples with RbF-PDT shows that inside grains, Rb is under the detection limit, but the Na concentration is enhanced as compared to the reference sample without Rb. At the GBs, a high concentration of Rb reaching 1.5 at. % was found, and Na and K (diffusing from the glass substrate) are also segregated at GBs but at lower concentrations as compared to Rb. The intentional introduction of Rb leads to significant changes in the chemical composition of CIGS matrix and at GBs, which might contribute to improve device efficiency.

  12. Structural and superconducting properties of epitaxial Fe{sub 1+y}Se{sub 1-x}Te{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Stefan; Yuan, Feifei; Grinenko, Vadim; Huehne, Ruben [Institute for Metallic Materials, IFW Dresden (Germany); Sala, Alberto; Putti, Marina [Dipartimento di Fisica, Universita di Genova (Italy)

    2015-07-01

    The iron based superconductor Fe(Se,Te) is in the center of much ongoing research. The reason for this is on the one hand its simple crystal structure, that consists only of stacked Fe(Se,Te) layers so that structural and superconducting properties can be connected more easily, on the other hand FeSe itself shows a high sensibility for strain and changes in stoichiometry and can have potentially very high critical temperatures under hydrostatic pressure or in monolayers. We investigate epitaxial thin films of Fe{sub 1+y}Se{sub 1-x}Te{sub x} grown by pulsed laser deposition on different single crystalline substrates. A high crystalline quality and a superconducting transition of up to about 20 K can be achieved using optimized deposition parameters. The influence of growth conditions, Te-doping, film thickness and post growth oxygen treatment on the structural and superconducting properties on these films will be presented in detail.

  13. A Comprehensive Study of One-Step Selenization Process for Cu(In1-x Ga x )Se2 Thin Film Solar Cells.

    Science.gov (United States)

    Chen, Shih-Chen; Wang, Sheng-Wen; Kuo, Shou-Yi; Juang, Jenh-Yih; Lee, Po-Tsung; Luo, Chih Wei; Wu, Kaung-Hsiung; Kuo, Hao-Chung

    2017-12-01

    In this work, aiming at developing a rapid and environmental-friendly process for fabricating CuIn 1-x Ga x Se 2 (CIGS) solar cells, we demonstrated the one-step selenization process by using selenium vapor as the atmospheric gas instead of the commonly used H 2 Se gas. The photoluminescence (PL) characteristics indicate that there exists an optimal location with superior crystalline quality in the CIGS thin films obtained by one-step selenization. The energy dispersive spectroscopy (EDS) reveals that the Ga lateral distribution in the one-step selenized CIGS thin film is intimately correlated to the blue-shifted PL spectra. The surface morphologies examined by scanning electron microscope (SEM) further suggested that voids and binary phase commonly existing in CIGS films could be successfully eliminated by the present one-step selenization process. The agglomeration phenomenon attributable to the formation of MoSe 2 layer was also observed. Due to the significant microstructural improvement, the current-voltage (J-V) characteristics and external quantum efficiency (EQE) of the devices made of the present CIGS films have exhibited the remarkable carrier transportation characteristics and photon utilization at the optimal location, resulting in a high conversion efficiency of 11.28%. Correlations between the defect states and device performance of the one-step selenized CIGS thin film were convincingly delineated by femtosecond pump-probe spectroscopy.

  14. Characterization of as-grown and Ge-ion implanted CuGaSe{sub 2} thin films prepared by the CCSVT technique

    Energy Technology Data Exchange (ETDEWEB)

    Doka Yamigno, Serge

    2006-08-15

    Single phase polycrystalline thin films of CuGaSe{sub 2} in the compositional range of 1.0=[Ga]/[Cu]=1.3, corresponding to a thickness ranging from 1.6 {mu}m to 1.9 {mu}m deposited onto plain or Mo-coated soda lime glass (SLG) were prepared and found to be polycrystalline with a strongly preferred <221> orientation. A combination of microstructural investigations of the films by TEM, EDX within the TEM and ERDA measurements has shown that CuGaSe{sub 2} thin films possess high crystalline bulk quality with Cu, Ga and Se homogeneously distributed within the CuGaSe{sub 2} bulk. One of the main result of this present work was found to be the accumulation of Ga in the region of the CuGaSe2/Mo interface and the dependence of the CuGaSe{sub 2} surface composition on the integral [Ga]/[Cu] ratio in the film, namely Ga- and Cu-poor, Se-rich surface for stoichiometric films; and Cu- poor, and Ga- and Se- rich surface for increasing [Ga]/[Cu] ratios. These observations were also supported by optical measurements carried out through photoluminescence and absorption measurements. In order to gain a better understanding of the influence of the extrinsic doping of the CuGaSe{sub 2} films and why many attempts towards the type inversion in the p-type CuGaSe2 compounds by varying the composition or by doping with extrinsic defects have failed, ion implantation was used to introduce Ge into CuGaSe{sub 2}. Photoluminescence of the Ge containing films has evidenced the presence of new defects such as donor levels in the band gap. Electron spin resonance measurements of the Ge- containing CuGaSe2 films has highlighted an additional ESR resonance observed at g=2.003 ascribed to donors. However, Curie paramagnetism up to room temperature for all the Ge implanted films, characteristic of localized states has been observed for this resonance. (orig.)

  15. Thin-film photovoltaic technology

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharya, R.N. [National Renewable Energy Laboratory, Golden, CO (United States)

    2010-07-01

    The high material and processing costs associated with single-crystal and polycrystalline silicon wafers that are commonly used in photovoltaic cells render these modules expensive. This presentation described thin-film solar cell technology as a promising alternative to silicon solar cell technology. Cadmium telluride (CdTe) thin films along with copper, indium, gallium, and selenium (CIGS) thin films have become the leaders in this field. Their large optical absorption coefficient can be attributed to a direct energy gap that allows the use of thin layers (1-2 {mu}m) of active material. The efficiency of thin-film solar cell devices based on CIGS is 20 per cent, compared to 16.7 per cent for thin-film solar cell devices based on CdTe. IBM recently reported an efficiency of 9.7 per cent for a new type of inorganic thin-film solar cell based on a Cu{sub 2}ZnSn(S, Se){sub 4} compound. The efficiency of an organic thin-film solar cell is 7.9 per cent. This presentation included a graph of PV device efficiencies and discussed technological advances in non-vacuum deposited, CIGS-based thin-film solar cells. 1 fig.

  16. Effect of 60Co γ-irradiation on structural and optical properties of thin films of Ga10Se80Hg10

    Science.gov (United States)

    Ahmad, Shabir; Asokan, K.; Shahid Khan, Mohd.; Zulfequar, M.

    2015-08-01

    Thin films of Ga10Se80Hg10 have been deposited onto a chemically cleaned Al2O3 substrates by thermal evaporation technique under vacuum. The investigated thin films are irradiated by 60Co γ-rays in the dose range of 50-150 kGy. X-ray diffraction patterns of the investigated thin films confirm the preferred crystallite growth occurs in the tetragonal phase structure. It also shows, the average crystallite size increases after γ-exposure, which indicates the crystallinity of the material increases after γ-irradiation. These results were further supported by surface morphological analysis carried out by scanning electron microscope and atomic force microscope which also shows the crystallinity of the material increases with increasing the γ-irradiation dose. The optical transmission spectra of the thin films at normal incidence were investigated in the spectral range from 190 to 1100 nm. Using the transmission spectra, the optical constants like refractive index (n) and extinction coefficient (k) were calculated based on Swanepoel's method. The optical band gap (Eg) was also estimated using Tauc's extrapolation procedure. The optical analysis shows: the value of optical band gap of investigated thin films decreases and the corresponding absorption coefficient increases continuously with increasing dose of γ-irradiation.

  17. AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    González, J.O. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); Shaji, S.; Avellaneda, D. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); Universidad Autónoma de Nuevo León-CIIDIT, Apodaca, Nuevo León, México (Mexico); Castillo, A.G.; Roy, T.K. Das [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, San Nicolás de los Garza, Nuevo León 66450, México (Mexico); and others

    2013-05-15

    Highlights: ► AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films were formed by heating Na{sub 2}SeSO{sub 3} dipped Sb{sub 2}S{sub 3}/Ag layers. ► S/Se ratio was varied by changing the dipping time in Na{sub 2}SeSO{sub 3} solution. ► Characterized the films using XRD, XPS, SEM, Optical and electrical measurements. ► Band gap engineering of 1−1.1 eV for x = 0.51 and 0.52 respectively. ► PV Glass/FTO/CdS/AgSb(S{sub x}Se{sub 1−x}){sub 2}/C were prepared showing V{sub oc} = 410 mV, J{sub sc} = 5.7 mA/cm{sup 2}. - Abstract: Silver antimony sulfoselenide (AgSb(S{sub x}Se{sub 1−x}){sub 2}) thin films were prepared by heating glass/Sb{sub 2}S{sub 3}/Ag layers after selenization using sodium selenosulphate solution. First, Sb{sub 2}S{sub 3} thin films were deposited on glass substrates from a chemical bath containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3}. Then Ag thin films were thermally evaporated onto glass/Sb{sub 2}S{sub 3}, followed by selenization by dipping in an acidic solution of Na{sub 2}SeSO{sub 3}. The duration of selenium dipping was varied as 30 min and 2 h. The heating condition was at 350 °C for 1 h in vacuum. Analysis of X-ray diffraction pattern of the thin films formed after heating showed the formation of AgSb(S{sub x}Se{sub 1−x}){sub 2}. Morphology and elemental analysis were done by scanning electron microscopy and energy dispersive X-ray detection. Depth profile of composition of the thin films was performed by X-ray Photoelectron Spectroscopy. The spectral study showed the presence of Ag, Sb, S, and Se, and the corresponding binding energy analysis confirmed the formation of AgSb(S{sub x}Se{sub 1−x}){sub 2}. Photovoltaic structures (PV) were prepared using AgSb(S{sub x}Se{sub 1−x}){sub 2} thin films as absorber and CdS thin films as window layers on FTO coated glass substrates. The PV structures were heated at 60–80 °C in air for 1 h to improve ohmic contact. Analysis of J–V characteristics of the PV structures showed V

  18. Refractive-index change caused by electrons in amorphous AsS and AsSe thin films doped with different metals by photodiffusion

    International Nuclear Information System (INIS)

    Nordman, Olli; Nordman, Nina; Pashkevich, Valfrid

    2001-01-01

    The refractive-index change caused by electrons was measured in amorphous AsS and AsSe thin films. Films were coated with different metals. Diffraction gratings were written by electron-beam lithography. The interactions of electrons in films with and without the photodiffusion of overcoated metal were compared. Incoming electrons caused metal atom and ion diffusion in both investigated cases. The metal diffusion was dependent on the metal and it was found to influence the refractive index. In some cases lateral diffusion of the metal was noticed. The conditions for applications were verified. Copyright 2001 Optical Society of America

  19. Crystal Structure, Optical, and Electrical Properties of SnSe and SnS Semiconductor Thin Films Prepared by Vacuum Evaporation Techniques for Solar Cell Applications

    Science.gov (United States)

    Ariswan; Sutrisno, H.; Prasetyawati, R.

    2017-05-01

    Thin films of SnSe and SnS semiconductors had been prepared by vacuum evaporation techniques. All prepared samples were characterized on their structure, optical, and electrical properties in order to know their application in technology. The crystal structure of SnSe and SnS was determined by X-Ray Diffraction (XRD) instrument. The morphology and chemical composition were obtained by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive of X-Ray Analysis (EDAX). The optical property such as band gap was determined by DR-UV-Vis (Diffuse Reflectance-Ultra Violet-Visible) spectroscopy, while the electrical properties were determined by measuring the conductivity by four probes method. The characterization results indicated that both SnSe and SnS thin films were polycrystalline. SnSe crystallized in an orthorhombic crystal system with the lattice parameters of a = 11.47 Å, b = 4.152 Å and c = 4.439 Å, while SnS had an orthorhombic crystal system with lattice parameters of a = 4.317 Å, b = 11.647 Å and c = 3.981 Å. Band gaps (Eg) of SnSe and SnS were 1.63 eV and 1.35 eV, respectively. Chemical compositions of both thin films were non-stoichiometric. Molar ratio of Sn : S was close to ideal which was 1 : 0.96, while molar ratio of Sn : S was 1 : 0.84. The surface morphology described the arrangement of the grains on the surface of the thin film with sizes ranging from 0.2 to 0.5 microns. Color similarity on the surface of the SEM images proved a homogenous thin layer.

  20. Effect of boron implantation on the electrical and photoelectrical properties of e-beam deposited Ag-In-Se thin films

    International Nuclear Information System (INIS)

    Colakoglu, T; Parlak, M; Kulakci, M; Turan, R

    2008-01-01

    In this study, e-beam evaporated Ag-In-Se (AIS) thin films were doped by the implantation of boron (B) ions at 75 keV with a dose of 1 x 10 15 ions cm -2 and a subsequent annealing process was applied to the doped AIS films at different temperatures under nitrogen atmosphere. The effects of implantation and annealing on the electrical and photoelectrical properties of AIS thin films were investigated through temperature dependent conductivity, spectral photoresponse and photoconductivity measurements under different illumination intensities. The electrical conductivity measurements showed that the room temperature conductivity values were determined as 2.4 x 10 -7 (Ω cm) -1 , 1.7 x 10 -6 (Ω cm) -1 and 8.9 x 10 -5 (Ω cm) -1 for B-doped films (B0), B-doped and annealed films at 200 deg. C (B2) and at 300 deg. C (B3), respectively. It was observed that the electrical conductivity improved as the annealing temperature increased up to 400 deg. C at which the AIS thin films showed degenerate semiconductor behaviour. The spectral distribution of the photoresponse curves indicated three local maxima located at 1.63, 1.79 and 2.01 eV for B0 type films, 1.65, 1.87 and 2.07 eV for B2 type films and 1.73, 2.02 and 2.32 eV for B3 type films at room temperature. These three different energy values were ascribed to the splitting of the valence band due to spin-orbit interaction and crystalline lattice field effects. The first energy values of each set were determined to be energy band gaps of the AIS thin films. The photoconductivity measurements as a function of temperature and illumination intensity were performed on the B-doped AIS thin films in order to determine the nature of recombination processes in the films. The photoconductivity values were found to be thermally quenched for all types of thin films and the variation of photocurrent as a function of illumination intensity showed that the dependence of photocurrent on the intensity was supralinear. The two

  1. CuIn{sub x}Ga{sub 1-x}Se{sub 2} thin films prepared by electron beam evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Venkatachalam, M.; Kannan, M.D.; Jayakumar, S.; Balasundaraprabhu, R.; Nandakumar, A.K. [Thin Film Center, Department of Physics, PSG College of Technology (India); Muthukumarasamy, N. [Department of Physics, Coimbatore Institute of Technology (India)

    2008-05-15

    CuIn{sub x}Ga{sub 1-x}Se{sub 2} bulk compound of three different compositions x=0.75, 0.80 and 0.85 have been prepared using individual elements of copper, indium, gallium and selenium. Thin films of CuIn{sub x}Ga{sub 1-x}Se{sub 2} have been deposited using the prepared bulk by electron beam evaporation method. The structural studies carried on the deposited films revealed that films annealed at 400 C are crystalline in nature exhibiting chalcopyrite phase. The position of the (1 1 2) peak in the X-ray diffractogram corresponding to the chalcopyrite phase has been found to be dependent on the percentage of gallium in the films. The composition of the prepared bulk and thin films has been identified using energy dispersive X-ray analysis. The photoluminescence spectra of the CuIn{sub x}Ga{sub 1-x}Se{sub 2} films exhibited sharp luminescence peaks corresponding to the band gap of the material. (author)

  2. Structural, optical and electrical properties of Cu{sub 2}FeSnX{sub 4} (X = S, Se) thin films prepared by chemical spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Khadka, Dhruba B.; Kim, JunHo, E-mail: jhk@inu.ac.kr

    2015-07-25

    Highlights: • CFTS(Se) thin films have been synthesized by low-cost spray-based deposition. • The fabricated films were found to be of stannite structure and p-type conductivity. • Band gaps of CFTS and CFTSe thin films are 1.37 and 1.11 eV, respectively. - Abstract: We report on fabrication of polycrystalline Cu{sub 2}FeSnX{sub 4} (X = S, Se) thin films by chemical spray pyrolysis subsequent with post-sulfurization and selenization. The post-annealing of as-sprayed Cu{sub 2}FeSnS{sub 4} (CFTS) films in sulfur and selenium ambient demonstrated drastically improved surface texture as well as crystallinity. The crystal lattice parameters calculated from X-ray diffraction patterns for post-annealed films were found to be consistent with stannite structure. The fabricated Cu{sub 2}FeSnS{sub 4} (CFTS) and Cu{sub 2}FeSnSe{sub 4} (CFTSe) films showed p-type conductivity with carrier concentration in the range of 10{sup 21} cm{sup −3} and mobility ∼1–5 cm{sup 2} V{sup −1} s{sup −1}. The band gap energies of post-sulfurized CFTS and post-selenized CFTSe films were estimated to be ∼1.37 eV and ∼1.11 eV with an error of ±0.02 eV by UV–Vis absorption, respectively, which are promising for photovoltaic application.

  3. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  4. Pyrolyzed thin film carbon

    Science.gov (United States)

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

    2010-01-01

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

  5. Growth of Cu(In,Al)(Se,S)2 thin films by selenization and sulfurization for a wide bandgap absorber

    International Nuclear Information System (INIS)

    Fujiwara, C.; Kawasaki, Y.; Sato, T.; Sugiyama, M.; Chichibu, S.F.

    2010-01-01

    Full text : Chalcopyrite structure Cu(In 1 .xAlx)(S y Se 1 -y) 2 (CIASS) alloys are attracting attention as promising candidates for the light-absorbing medium of high conversion efficiency, low cost, and lightweight solar cells. In addition, according to the wide variation in the bandgap energy (1.0-3.5eV), multiple-junction or tandem solar cells able to be fabricated using CIASS films of different compositions, x and y. In fact, several research groups have recently fabricated Cu(In,Al)Se 2 -based solar cells, and a high μ of 16.9 percent has been demonstrated. The sulfurization following selenization of Cu(In,Ga)Se2 (CIGS) films is believed to be promising for bandgap engineering of absorber material. Furthermore, it has been reported that the controlled incorporation of sulfur into CIGS films reduces the carrier recombination in the space charge region due to the deep trap states. Therefore, the sulfurization following selenization is expected to be used as a method of growth of CIASS films. However, sulfurization condition following selenization for obtaining CIASS films has not been clarified. The crystal growth of CIASS must be studied for solar cell applications. In this study, the advantages of using sulfurization for the growth of CIASS will be presented. Cu-In-Al precursors were selenized using diethylselenide (DESe) at 515-570 degrees Celsium for 60- 90 min under atmospheric pressure. The flow rates of DESe and N 2 carrier gases were 35 imol/min and 2 L/min, respectively. The films were then sulfurized at 550 degrees Celsium using S vapor. These films were characterized by SEM, EDX, XRD, and PL measurements. Using the selenization and sulfurization technique, polycrystalline Cu(In,Al)Se 2 , CuIn(Se,S) 2 , CuInS 2 films with thickness of approximately 2.0 im were formed without additional annealing. The films adhered well to the Mo/SLG substrate, which was confirmed by the peeling test. Phase separations, i.e. distinct peaks corresponding to CuInSe 2

  6. Effect of Annealing Temperature on CuInSe2/ZnS Thin-Film Solar Cells Fabricated by Using Electron Beam Evaporation

    Directory of Open Access Journals (Sweden)

    H. Abdullah

    2013-01-01

    Full Text Available CuInSe2 (CIS thin films are successfully prepared by electron beam evaporation. Pure Cu, In, and Se powders were mixed and ground in a grinder and made into a pellet. The pallets were deposited via electron beam evaporation on FTO substrates and were varied by varying the annealing temperatures, at room temperature, 250°C, 300°C, and 350°C. Samples were analysed by X-ray diffractometry (XRD for crystallinity and field-emission scanning electron microscopy (FESEM for grain size and thickness. I-V measurements were used to measure the efficiency of the CuInSe2/ZnS solar cells. XRD results show that the crystallinity of the films improved as the temperature was increased. The temperature dependence of crystallinity indicates polycrystalline behaviour in the CuInSe2 films with (1 1 1, (2 2 0/(2 0 4, and (3 1 2/(1 1 6 planes at 27°, 45°, and 53°, respectively. FESEM images show the homogeneity of the CuInSe2 formed. I-V measurements indicated that higher annealing temperatures increase the efficiency of CuInSe2 solar cells from approximately 0.99% for the as-deposited films to 1.12% for the annealed films. Hence, we can conclude that the overall cell performance is strongly dependent on the annealing temperature.

  7. Cu2ZnSnSe4 Thin Film Solar Cell with Depth Gradient Composition Prepared by Selenization of Sputtered Novel Precursors.

    Science.gov (United States)

    Lai, Fang-I; Yang, Jui-Fu; Chen, Wei-Chun; Kuo, Shou-Yi

    2017-11-22

    In this study, we proposed a new method for the synthesis of the target material used in a two stage process for preparation of a high quality CZTSe thin film. The target material consisting of a mixture of Cu x Se and Zn x Sn 1-x alloy was synthesized, providing a quality CZTSe precursor layer for highly efficient CZTSe thin film solar cells. The CZTSe thin film can be obtained by annealing the precursor layers through a 30 min selenization process under a selenium atmosphere at 550 °C. The CZTSe thin films prepared by using the new precursor thin film were investigated and characterized using X-ray diffraction, Raman scattering, and photoluminescence spectroscopy. It was found that diffusion of Sn occurred and formed the CTSe phase and Cu x Se phase in the resultant CZTSe thin film. By selective area electron diffraction transmission electron microscopy images, the crystallinity of the CZTSe thin film was verified to be single crystal. By secondary ion mass spectroscopy measurements, it was confirmed that a double-gradient band gap profile across the CZTSe absorber layer was successfully achieved. The CZTSe solar cell with the CZTSe absorber layer consisting of the precursor stack exhibited a high efficiency of 5.46%, high short circuit current (J SC ) of 37.47 mA/cm 2 , open circuit voltage (V OC ) of 0.31 V, and fill factor (F.F.) of 47%, at a device area of 0.28 cm 2 . No crossover of the light and dark current-voltage (I-V) curves of the CZTSe solar cell was observed, and also, no red kink was observed under red light illumination, indicating a low defect concentration in the CZTSe absorber layer. Shunt leakage current with a characteristic metal/CZTSe/metal leakage current model was observed by temperature-dependent I-V curves, which led to the discovery of metal incursion through the CdS buffer layer on the CZTSe absorber layer. This leakage current, also known as space charge-limited current, grew larger as the measurement temperature increased and

  8. Effect of Composition on Electrical and Optical Properties of Thin Films of Amorphous GaxSe100−x Nanorods

    Directory of Open Access Journals (Sweden)

    Abdallah El-Hamidy SM

    2010-01-01

    Full Text Available Abstract We report the electrical and optical studies of thin films of a-GaxSe100−x nanorods (x = 3, 6, 9 and 12. Thin films of a-GaxSe100−x nanorods have been synthesized thermal evaporation technique. DC electrical conductivity of deposited thin films of a-GaxSe100−x nanorods is measured as a function of temperature range from 298 to 383 K. An exponential increase in the dc conductivity is observed with the increase in temperature, suggesting thereby a semiconducting behavior. The estimated value of activation energy decreases on incorporation of dopant (Ga content in the Se system. The calculated value of pre-exponential factor (σ0 is of the order of 101 Ω−1 cm−1, which suggests that the conduction takes place in the band tails of localized states. It is suggested that the conduction is due to thermally assisted tunneling of the carriers in the localized states near the band edges. On the basis of the optical absorption measurements, an indirect optical band gap is observed in this system, and the value of optical band gap decreases on increasing Ga concentration.

  9. Characterization of structural defects in SnSe2 thin films grown by molecular beam epitaxy on GaAs (111)B substrates

    Science.gov (United States)

    Tracy, Brian D.; Li, Xiang; Liu, Xinyu; Furdyna, Jacek; Dobrowolska, Margaret; Smith, David J.

    2016-11-01

    Tin selenide thin films have been grown by molecular beam epitaxy on GaAs (111)B substrates at a growth temperature of 150 °C, and a microstructural study has been carried out, primarily using the technique of transmission electron microscopy. The Se:Sn flux ratio during growth was systematically varied and found to have a strong impact on the resultant crystal structure and quality. Low flux ratios (Se:Sn=3:1) led to defective films consisting primarily of SnSe, whereas high flux ratios (Se:Sn>10:1) gave higher quality, single-phase SnSe2. The structure of the monoselenide films was found to be consistent with the Space Group Pnma with the epitaxial growth relationship of [011]SnSe// [ 1 1 bar 0 ] GaAs, while the diselenide films were consistent with the Space Group P 3 bar m1 , and had the epitaxial growth relationship [ 2 1 bar 1 bar 0 ]SnSe2// [ 1 1 bar 0 ] GaAs.

  10. Optical properties change in laser-induced Te/As{sub 2}Se{sub 3} chalcogenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Behera, Mukta; Naik, Ramakanta [Utkal University, Department of Physics, Bhubaneswar (India)

    2016-10-15

    In the present work, we report the change in optical parameters due to the deposition and photo-induced diffusion of Te layer into the chalcogenide As{sub 2}Se{sub 3} film. The photo-diffusion creates a solid solution of As-Se-Te which has potential application in optical devices. The Te/As{sub 2}Se{sub 3} bilayer films prepared by thermal evaporation technique were studied by various experimental techniques. The photo-diffusion of Te into As{sub 2}Se{sub 3} matrix was done by 532-nm laser irradiation. The structure of the As{sub 2}Se{sub 3}, as-prepared and irradiated Te/As{sub 2}Se{sub 3} films was studied by X-ray diffraction which were amorphous in nature. The presence of all the elements was checked by energy-dispersive X-ray analysis, and the optical transmission spectra were recorded by Fourier transform infrared spectrometer. The optical band gap is reduced by the deposition and diffusion of Te into As{sub 2}Se{sub 3} film which is due to the increase in density of defect states in the gap region. The transmission is decreased, whereas the absorption efficiency is increased with the increase in disorderness. The X-ray photoelectron spectroscopy carried out on these films gives information about the bonding change due to the photo-diffusion process. Therefore, this is an important result which will open up new directions for the application of this material in semiconducting devices. (orig.)

  11. Effect of vacuum annealing and substrate temperature on structural and optical properties of ZnIn2Se4 thin films

    Science.gov (United States)

    El-Nahass, M. M.; Attia, A. A.; Salem, G. F.; Ali, H. A. M.; Ismail, M. I.

    2013-09-01

    Zinc indium selenide (ZnIn2Se4) thin films were prepared by the thermal evaporation technique with high deposition rate. The effect of thermal annealing in vacuum on the crystallinity of the as-deposited films was studied at different temperatures (523, 573 and 623 K). The effect of substrate temperature (623 K) for different thickness values (173, 250, 335 and 346 nm) on the optical parameters of ZnIn2Se4 was also studied. The structural studies showed nanocrystalline nature of the room temperature (300 K) deposited films with crystallite size of about a few nanometers. The crystallite size increased up to 31 nm with increasing the annealing temperature in vacuum. From the reflection and transmission data, the refractive index n and the extinction coefficient k were estimated for ZnIn2Se4 thin films and they were found to be independent of film thickness. Analysis of the absorption coefficient data of the as-deposited films revealed the existence of allowed direct and indirect transitions with optical energy gaps of 2.21 eV and 1.71 eV, respectively. These values decreased with increasing annealing temperature. At substrate temperature of 623 K, the direct band gap increased to 2.41 eV whereas the value of indirect band gap remained nearly unchanged. The dispersion analysis showed that the values of the oscillator energy Eo, dispersion energy Ed, dielectric constant at infinite frequency ε∞, and lattice dielectric constant εL were changed appreciably under the effect of annealing and substrate temperature. The covalent nature of structure was studied as a function of the annealing and substrate temperature using an empirical relation for the dispersion energy Ed. Generalized Miller's rule and linear refractive index were used to estimate the nonlinear susceptibility and nonlinear refractive index of the thin films.

  12. Influence of substrate type on transport properties of superconducting FeSe0.5Te0.5 thin films

    International Nuclear Information System (INIS)

    Yuan, Feifei; Shi, Zhixiang; Iida, Kazumasa; Langer, Marco; Hänisch, Jens; Hühne, Ruben; Schultz, Ludwig; Ichinose, Ataru; Tsukada, Ichiro; Sala, Alberto; Putti, Marina

    2015-01-01

    FeSe 0.5 Te 0.5 thin films were grown by pulsed laser deposition on CaF 2 , LaAlO 3 and MgO substrates and structurally and electro-magnetically characterized in order to study the influence of the substrate on their transport properties. The in-plane lattice mismatch between FeSe 0.5 Te 0.5 bulk and the substrate shows no influence on the lattice parameters of the films, whereas the type of substrate affects the crystalline quality of the films and, therefore, the superconducting properties. The film on MgO showed an extra peak in the angular dependence of critical current density J c (θ) at θ = 180° (H||c), which arises from c-axis defects as confirmed by transmission electron microscopy. In contrast, no J c (θ) peaks for H||c were observed in films on CaF 2 and LaAlO 3 . J c (θ) can be scaled successfully for both films without c-axis correlated defects by the anisotropic Ginzburg–Landau approach with appropriate anisotropy ratio γ J . The scaling parameter γ J is decreasing with decreasing temperature, which is different from what we observed in FeSe 0.5 Te 0.5 films on Fe-buffered MgO substrates. (paper)

  13. Terahertz conductivity measurement of FeSe0.5Te0.5 and Co-doped BaFe2As2 thin films

    International Nuclear Information System (INIS)

    Nakamura, D.; Akiike, T.; Takahashi, H.; Nabeshima, F.; Imai, Y.; Maeda, A.; Katase, T.; Hiramatsu, H.; Hosono, H.; Komiya, S.; Tsukada, I.

    2011-01-01

    We investigated the THz conductivity of FeSe 0.5 Te 0.5 and Ba (Fe 2-x Co x )As 2 thin films. We estimated the superconducting gap energy values. We found anomolous conductivity spectrum in the antiferromagnetic phase. The terahertz (THz) conductivity of FeSe 0.5 Te 0.5 ('11'-type) and Co-doped BaFe 2 As 2 ('122'-type) thin films are investigated. For '11'-type, the frequency dependence of the complex conductivity can be understood as that of BCS-type superconductor near the superconducting gap energy, and we estimated the superconducting gap energy to be 0.6 meV. For '122'-type, we estimated the superconducting gap energy to be 2.8 meV, which is considered to be the superconducting gap opened at the electron-type Fermi surface near the M point.

  14. Nanoscale semiconductor Pb{sub 1-x}Sn{sub x}Se (x = 0.2) thin films synthesized by electrochemical atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lin Shaoxiong; Zhang Xin; Shi Xuezhao; Wei Jinping; Lu Daban; Zhang Yuzhen; Kou Huanhuan [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Wang Chunming, E-mail: wangcm@lzu.edu.cn [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2011-04-15

    In this paper the fabrication and characterization of IV-VI semiconductor Pb{sub 1-x}Sn{sub x}Se (x = 0.2) thin films on gold substrate by electrochemical atomic layer deposition (EC-ALD) method at room temperature are reported. Cyclic voltammetry (CV) is used to determine approximate deposition potentials for each element. The amperometric I-t technique is used to fabricate the semiconductor alloy. The elements are deposited in the following sequence: (Se/Pb/Se/Pb/Se/Pb/Se/Pb/Se/Sn ...), each period is formed using four ALD cycles of PbSe followed by one cycle of SnSe. Then the deposition manner above is cyclic repeated till a satisfactory film with expected thickness of Pb{sub 1-x}Sn{sub x}Se is obtained. The morphology of the deposit is observed by field emission scanning electron microscopy (FE-SEM). X-ray diffraction (XRD) pattern is used to study its crystalline structure; X-ray photoelectron spectroscopy (XPS) of the deposit indicates an approximate ratio 1.0:0.8:0.2 of Se, Pb and Sn, as the expected stoichiometry for the deposit. Open-circuit potential (OCP) studies indicate a good p-type property, and the good optical activity makes it suitable for fabricating a photoelectric switch.

  15. Zinc concentration effect on structural, optical and electrical properties of Cd{sub 1−x}Zn{sub x}Se thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akaltun, Yunus [Department of Electrical and Electronic, Engineering Faculty, Erzincan University, Erzincan (Turkey); Yıldırım, M. Ali, E-mail: mayildirim@erzincan.edu.tr [Department of Physics, Science and Art Faculty, Erzincan University, Erzincan (Turkey); Ateş, Aytunç [Department of Material Engineering, Engineering and Natural Sciences Faculty, Yıldırım Beyazıt University, Ankara (Turkey); Yıldırım, Muhammet [Department of Physics, Science Faculty, Atatürk University, Erzurum (Turkey)

    2012-11-15

    Highlights: ► Cd{sub 1−x}Zn{sub x}Se thin films were deposited using SILAR method. ► The electron effective mass, refractive index, dielectric constant values were calculated by using the energy bandgap values as a function of the zinc concentration (x). ► The resistivity and activation energy changed as a function of the zinc concentration (x). -- Abstract: Cd{sub 1−x}Zn{sub x}Se thin films with different compositions (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) were deposited on glass substrates using successive ionic layer adsorption and reaction (SILAR) method at room temperature and ambient pressure. The zinc concentration (x) effect on the structural, morphological, optical and electrical properties of Cd{sub 1−x}Zn{sub x}Se thin films were investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all the films exhibited polycrystalline nature and were covered well on glass substrates. The energy dispersive X-ray (EDAX) analysis confirmed nearly stoichiometric deposition of the films. The energy bandgap values were changed from 1.99 to 2.82 eV depending on the zinc concentration. Bowing parameter was calculated as 0.08 eV. The electron effective mass (m{sub e}*/m{sub o}), refractive index (n), optical static and high frequency dielectric constants (ε{sub o}, ε{sub ∞}) values were calculated by using the energy bandgap values as a function of the zinc concentration. The resistivity values of the films changed between 10{sup 5} and 10{sup 7} Ω cm with increasing zinc concentration at room temperature.

  16. Syntheses and characterization of thin films of Te{sub 94}Se{sub 6} nanoparticles for semiconducting and optical devices

    Energy Technology Data Exchange (ETDEWEB)

    Salah, Numan, E-mail: nsalah@kau.edu.sa [Center of Nanotechnology, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Habib, Sami S.; Memic, Adnan [Center of Nanotechnology, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Alharbi, Najlaa D. [Center of Nanotechnology, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Sciences Faculty for Girls, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Babkair, Saeed S. [Center of Nanotechnology, Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah-21589 (Saudi Arabia); Khan, Zishan H. [Department of Applied Sciences and Humanities, Jamia Millia Islamia (Central University), New Delhi-110025 (India)

    2013-03-01

    Thin films of Te{sub 94}Se{sub 6} nanoparticles were synthesized using the physical vapor condensation technique at different argon (Ar) pressures. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy, absorption spectrum, photoluminescence (PL) and Raman spectroscopy. XRD results show that the as-grown films have a polycrystalline structure. SEM images display uniform nanoparticles in these films where the size increases from ∼ 12 to about 60 nm by decreasing Ar pressure from 667 to 267 Pa. These as-grown thin films were found to have direct band gaps, whose value decreases with increasing particle size. The absorption and extinction coefficients for these films were also investigated. PL emission spectra exhibit three bands peaking at 666, 718 and 760 nm, while Raman spectra displayed three bands located at 123, 143 and 169 cm{sup −1}. No significant changes are observed in positions or intensities of these bands by decreasing the Ar pressure, except that of the last band of PL; where the intensity increases. The obtained results on this Te{sub 94}Se{sub 6} nanomaterial especially its controlled direct bandgap might be useful for development of optical disks and other semiconducting devices. - Highlights: ► Thin films of Te{sub 94}Se{sub 6} nanoparticles were grown at different argon (Ar) pressures. ► Size of the nanoparticles increased by decreasing Ar pressure. ► They have direct band gap, whose value decreases by increasing the particle size. ► These nanomaterials might be useful for development of semiconducting devices.

  17. Colloidal Precursors from 'Ball-Milling in Liquid Medium' Process for CuInSe2 Thin Film

    International Nuclear Information System (INIS)

    Chung, Jae Hoon; Kim, Seung Joo

    2010-01-01

    CIS thin film can be fabricated by using the precursor obtained through ball-milling the elemental reagents in liquid media. The amorphous colloidal precursor with good dispersity was prepared in the medium that contains strong base and polar solvent (2 M ethylenediamine in DMF solution as used in this study). The 'ball-milling in liquid medium' method requires only elemental sources as starting materials and a proper solution so that it can be employed without additional processes for separation and purification. As a simple and less-toxic preparative route, this method would be practically available to prepare CIS-related solar cells. CuInSe 2 (CIS) and related chalcopyrite compounds are very promising materials for thin film solar cells due to their favorable band gap, high optical absorption coefficient and long-term stability. CIS-based solar cells have shown the highest conversion efficiency reaching a value of 20%. However, the vacuum-based processes that are used to fabricate CIS thin-films have some drawbacks such as the complexity in process, high production cost and difficulty in scaling up. Recently, several research groups have proposed different non-vacuum deposition processes for CIS solar cell. For example, H. W. Hillhouse et al. prepared the CIS absorber layer by using 'nanocrystal ink method' in which a colloidal nanocrystal ink was obtained from reaction of CuCl, InCl 3 and Se in oleylamine. D. B. Mitzi et al. used a solution-based precursor that was prepared by dissolution of Cu 2 Se, In 2 Se 3 , Ga 2 Se 3 and Se in hydrazine to fabricate the Ga-containing absorber layer, Cu(In,Ga)Se 2

  18. Reliable wet-chemical cleaning of natively oxidized high-efficiency Cu(In,Ga)Se2 thin-film solar cell absorbers

    Science.gov (United States)

    Lehmann, Jascha; Lehmann, Sebastian; Lauermann, Iver; Rissom, Thorsten; Kaufmann, Christian A.; Lux-Steiner, Martha Ch.; Bär, Marcus; Sadewasser, Sascha

    2014-12-01

    Currently, Cu-containing chalcopyrite-based solar cells provide the highest conversion efficiencies among all thin-film photovoltaic (PV) technologies. They have reached efficiency values above 20%, the same performance level as multi-crystalline silicon-wafer technology that dominates the commercial PV market. Chalcopyrite thin-film heterostructures consist of a layer stack with a variety of interfaces between different materials. It is the chalcopyrite/buffer region (forming the p-n junction), which is of crucial importance and therefore frequently investigated using surface and interface science tools, such as photoelectron spectroscopy and scanning probe microscopy. To ensure comparability and validity of the results, a general preparation guide for "realistic" surfaces of polycrystalline chalcopyrite thin films is highly desirable. We present results on wet-chemical cleaning procedures of polycrystalline Cu(In1-xGax)Se2 thin films with an average x = [Ga]/([In] + [Ga]) = 0.29, which were exposed to ambient conditions for different times. The hence natively oxidized sample surfaces were etched in KCN- or NH3-based aqueous solutions. By x-ray photoelectron spectroscopy, we find that the KCN treatment results in a chemical surface structure which is - apart from a slight change in surface composition - identical to a pristine as-received sample surface. Additionally, we discover a different oxidation behavior of In and Ga, in agreement with thermodynamic reference data, and we find indications for the segregation and removal of copper selenide surface phases from the polycrystalline material.

  19. Preparation and Characterization of Cu(In,GaSe2 Thin Films by Selenization of Cu0.8Ga0.2 and In2Se3 Precursor Films

    Directory of Open Access Journals (Sweden)

    Jiang Liu

    2012-01-01

    Full Text Available Se-containing precursor films with two different compositions were prepared by magnetron sputtering from and targets, and then were selenized using Se vapor. The effects of precursor composition and selenization temperature on the film properties were investigated. The results show that Se phase plays a critical role in film growth and electrical properties of CIGS films. The Cu-rich films exhibit different surface morphology and better crystallinity, as compared to the Cu-poor films. All the CIGS films exhibit p-type conductivity. The resistivity of the Cu-rich films is about three orders of magnitude lower than that of the Cu-poor films, which is attributed to the presence of p-type highly conductive Se phase.

  20. Electrochemical preparation and characterization of CuInSe{sub 2} thin films for photovoltaic applications; Preparacion electroquimica y caracterizacion de laminas delgadas de CuInSe{sub 2} para aplicaciones fotovoltaicas

    Energy Technology Data Exchange (ETDEWEB)

    Guillen Arqueros, C

    1993-12-31

    The objective of this work has been to investigate the electrodeposition as a low-cost, large-area fabrication process to obtain CuInSe{sub 2} this films for efficient photovoltaic devices. this objective entails the elucidation of thin film deposition mechanism, the study of the fundamental properties of electrodeposited material, and also the modification of their physical and chemical parameters for photovoltaic applications. CuInSe{sub 2} thin films have been successfully electrodeposited from a citric was characterized by compositional, structural, electrical, optical and electrochemical measurements, relating their properties with the preparation parameters and also studying the effect of various thermal and chemical treatments. The results showed post-deposition treatment are needed for optimizing these films for solar cells fabrication: first, an annealing in inert atmosphere at temperatures above 400 degrees celsius to obtain a high recrystallization in the chalcopyrite structure, and after a chemical etching in KCN solution to remove secondary phases of Cu{sub x}Se and Se which are frequently electrodeposited with the CuInSe{sub 2}. The treated samples showed appropriate photovoltaic activity in a semiconductor-electrolite liquid junction. (author) 193 ref.

  1. Surface and interface states of Bi{sub 2}Se{sub 3} thin films investigated by optical second-harmonic generation and terahertz emission

    Energy Technology Data Exchange (ETDEWEB)

    Hamh, S. Y.; Park, S.-H.; Lee, J. S., E-mail: jsl@gist.ac.kr [Department of Physics and Photon Science, School of Physics and Chemistry, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of); Jerng, S.-K.; Jeon, J. H.; Chun, S. H. [Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of); Jeon, J. H.; Kahng, S. J. [Department of Physics, Korea University, Seoul 136-701 (Korea, Republic of); Yu, K.; Choi, E. J. [Department of Physics, University or Seoul, Seoul 130-743 (Korea, Republic of); Kim, S.; Choi, S.-H. [Department of Applied Physics, College of Applied Science, Kyung Hee University, Yongin 446-701 (Korea, Republic of); Bansal, N. [Department of Electrical and Computer Engineering, Rutgers, The state University of New Jersey, Piscataway, New Jersey 08854 (United States); Oh, S. [Department of Physics and Astronomy, Rutgers, The state University of New Jersey, Piscataway, New Jersey 08854 (United States); Park, Joonbum; Kho, Byung-Woo; Kim, Jun Sung [Department of Physics, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2016-02-01

    We investigate the surface and interface states of Bi{sub 2}Se{sub 3} thin films by using the second-harmonic generation technique. Distinct from the surface of bulk crystals, the film surface and interface show the isotropic azimuth dependence of second-harmonic intensity, which is attributed to the formation of randomly oriented domains on the in-plane. Based on the nonlinear susceptibility deduced from the model fitting, we determine that the surface band bending induced in a space charge region occurs more strongly at the film interface facing the Al{sub 2}O{sub 3} substrate or capping layer compared with the interface facing the air. We demonstrate that distinct behavior of the terahertz electric field emitted from the samples can provide further information about the surface electronic state of Bi{sub 2}Se{sub 3}.

  2. How the Starting Precursor Influences the Properties of Polycrystalline CuInGaSe2 Thin Films Prepared by Sputtering and Selenization

    Directory of Open Access Journals (Sweden)

    Greta Rosa

    2016-05-01

    Full Text Available Cu(In,GaSe2 (CIGS/CdS thin-film solar cells have reached, at laboratory scale, an efficiency higher than 22.3%, which is one of the highest efficiencies ever obtained for thin-film solar cells. The research focus has now shifted onto fabrication processes, which have to be easily scalable at an industrial level. For this reason, a process is highlighted here which uses only the sputtering technique for both the absorber preparation and the deposition of all the other materials that make up the cell. Particular emphasis is placed on the comparison between different precursors obtained with either In2Se3 and Ga2Se3 or InSe and GaSe as starting materials. In both cases, the precursor does not require any heat treatment, and it is immediately ready to be selenized. The selenization is performed in a pure-selenium atmosphere and only lasts a few minutes at a temperature of about 803 K. Energy conversion efficiencies in the range of 15%–16% are reproducibly obtained on soda-lime glass (SLG substrates. Similar results are achieved if commercial ceramic tiles are used as a substrate instead of glass. This result is especially useful for the so-called building integrated photovoltaic. Cu(In,GaSe2-based solar cells grown directly on ceramic tiles are ideal for the fabrication of ventilated façades in low impact buildings.

  3. Determination of optical constant and dispersion parameters of Se{sub 75}Sb{sub 10}In{sub 15} thin film characterized by wide band gap

    Energy Technology Data Exchange (ETDEWEB)

    Abd-Elrahman, M.I.; Abu-Sehly, A.A.; El-sonbaty, Sherouk Sh.; Hafiz, M.M. [Assiut University, Physics Department, Faculty of Science, Assiut (Egypt)

    2017-02-15

    Chalcogenide Se{sub 75}Sb{sub 10}In{sub 15} thin films of different thickness (50-300 nm) are deposited using thermal evaporation technique. The thermogram of the chalcogenide bulk Se{sub 75}Sb{sub 10}In{sub 15} is obtained using a differential scanning calorimetry (DSC). The crystallization temperature T{sub c}, peak crystallization temperature T{sub p} and melting temperature T{sub m}, are identified. The X-ray diffraction (XRD) examination indicates the crystallinity of the as-deposited film decreases with increasing of thickness. Optical transmission and reflection spectra are recorded in the wavelength range of the incident photons from 250 to 2500 nm. It is found that the film thickness affects the absorption coefficient, refractive index, extinction coefficient and the width of the tails of localized states in the gap region. The absorption mechanism of the as-deposited films is a direct allowed transition. The optical band gap energy (E{sub g}) decreases from 3.31 to 2.51 eV with increasing the film thickness from 50 to 300 nm. The behavior of E{sub g} is explained on the basis of the structure disorders in the thicker films. The effect of the film thickness on the single-oscillator and dispersion energies is studied by the dispersion analyses of the refractive index. (orig.)

  4. In situ, real-time thickness measurement techniques for bath-deposited CdS thin films on Cu(In,Ga)Se2

    International Nuclear Information System (INIS)

    Mann, Jonathan R.; Noufi, Rommel

    2012-01-01

    A technique has been developed that can measure the thickness of a 30–70 nm thin film of cadmium sulfide on a Cu(In,Ga)Se 2 substrate, in real time, as it grows in a chemical bath. The technique does not damage the film, and can be used to monitor batch depositions and roll-to-roll depositions with equal accuracy. The technique is based on reflectance spectroscopy through the chemical bath. - Highlights: ► Reflection spectra were collected during the chemical bath deposition of CdS. ► Two algorithms were generated to extract film thickness from each spectrum. ► Two conventional techniques were used to independently verify CdS film thicknesses. ► The accuracies of the algorithms are within 7% of the actual thicknesses. ► The algorithms offer in situ, real time thicknesses through the chemical bath.

  5. In situ observation of electron-beam-induced dewetting of CdSe thin film embedded in SiO2

    DEFF Research Database (Denmark)

    Fabrim, Zacarias Eduardo; Kjelstrup-Hansen, Jakob; Fichtner, Paulo F. P.

    In this work we show the dewetting process of the CdSe thin films induced by electron beam irradiation. A multilayer heterostructure of SiO2/CdSe/SiO2 was made by a magnetron sputtering process. A plan-view (PV) sample was irradiated with 200 kV electrons in the TEM with two current densities: 0.......33 A.cm2 and 1.0 A.cm2 and at 80 kV with 0.37 A.cm2. The dewetting of the CdSe film is inferred by a number of micrographs taken during the irradiation. The microstructural changes were analyzed under the assumption of being induced by ballistic collision effects in the absence of sample heating....

  6. Electronic structure of the Zn(O,S)/Cu(In,Ga)Se2 thin-film solar cell interface

    Energy Technology Data Exchange (ETDEWEB)

    Mezher, Michelle [Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), Las Vegas NV 89154 USA; Garris, Rebekah [National Renewable Energy Laboratory (NREL), Golden CO 80401 USA; Mansfield, Lorelle M. [National Renewable Energy Laboratory (NREL), Golden CO 80401 USA; Horsley, Kimberly [Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), Las Vegas NV 89154 USA; Weinhardt, Lothar [Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), Las Vegas NV 89154 USA; Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen Germany; ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen Germany; Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe Germany; Duncan, Douglas A. [Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), Las Vegas NV 89154 USA; Blum, Monika [Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), Las Vegas NV 89154 USA; Rosenberg, Samantha G. [Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), Las Vegas NV 89154 USA; Bär, Marcus [Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), Las Vegas NV 89154 USA; Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, 14109 Berlin Germany; Institut für Physik und Chemie, Brandenburgische Technische Universität Cottbus-Senftenberg, 03046 Cottbus Germany; Ramanathan, Kannan [National Renewable Energy Laboratory (NREL), Golden CO 80401 USA; Heske, Clemens [Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV), Las Vegas NV 89154 USA; Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen Germany; ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen Germany; Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT), 76128 Karlsruhe Germany

    2016-03-10

    The electronic band alignment of the Zn(O,S)/Cu(In,Ga)Se2 interface in high-efficiency thin-film solar cells was derived using X-ray photoelectron spectroscopy, ultra-violet photoelectron spectroscopy, and inverse photoemission spectroscopy. Similar to the CdS/Cu(In,Ga)Se2 system, we find an essentially flat (small-spike) conduction band alignment (here: a conduction band offset of (0.09 +/- 0.20) eV), allowing for largely unimpeded electron transfer and forming a likely basis for the success of high-efficiency Zn(O,S)-based chalcopyrite devices. Furthermore, we find evidence for multiple bonding environments of Zn and O in the Zn(O,S) film, including ZnO, ZnS, Zn(OH)2, and possibly ZnSe.

  7. Optical properties and defect levels in a surface layer found on CuInSe{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Abulfotuh, F.; Wangensteen, T.; Ahrenkiel, R.; Kazmerski, L.L. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    In this paper the authors have used photoluminescence (PL) and wavelength scanning ellipsometry (WSE) to clarify the relationship among the electro-optical properties of copper indium diselenide (CIS) thin films, the type and origin of dominant defect states, and device performance. The PL study has revealed several shallow acceptor and donor levels dominating the semiconductor. PL emission from points at different depths from the surface of the CIS sample has been obtained by changing the angle of incidence of the excitation laser beam. The resulting data were used to determine the dominant defect states as a function of composition gradient at the surface of the chalcopyrite compound. The significance of this type of measurement is that it allowed the detection of a very thin layer with a larger bandgap (1.15-1.26 eV) than the CIS present on the surface of the CIS thin films. The presence of this layer has been correlated by several groups to improvement of the CIS cell performance. An important need that results from detecting this layer on the surface of the CIS semiconductor is the determination of its thickness and optical constants (n, k) as a function of wavelength. The thickness of this surface layer is about 500 {Angstrom}.

  8. Deposition and characterization of graded Cu(In{sub 1-x}Ga{sub x})Se{sub 2} thin films by spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Babu, B.J. [Department of Electrical Engineering-SEES, CINVESTAV-IPN, Avenida IPN 2508, San Pedro Zacatenco, D.F. C.P 07360 (Mexico); Institute of Molecules and Materials, UMR-CNRS 6283, Université du Maine, Avenue O. Messiaen, F-72085 Le Mans (France); Velumani, S., E-mail: velu@cinvestav.mx [Department of Electrical Engineering-SEES, CINVESTAV-IPN, Avenida IPN 2508, San Pedro Zacatenco, D.F. C.P 07360 (Mexico); College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kassiba, A. [Institute of Molecules and Materials, UMR-CNRS 6283, Université du Maine, Avenue O. Messiaen, F-72085 Le Mans (France); Asomoza, R. [Department of Electrical Engineering-SEES, CINVESTAV-IPN, Avenida IPN 2508, San Pedro Zacatenco, D.F. C.P 07360 (Mexico); Chavez-Carvayar, J.A. [Instituto Investigaciones en Materiales-UNAM, Ciudad Universitario, D.F.Mexico (Mexico); Yi, Junsin, E-mail: yi@yurim.skku.ac.kr [College of Information and Communication Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-07-15

    Cu(In{sub 1-x}Ga{sub x})Se{sub 2} (CIGS) thin films and their graded (x = 1 to 0) layer were grown on soda lime glass substrates using chemical spray pyrolysis (CSP) at different substrate temperatures (T{sub s}). After optimization of T{sub s}, depositions were carried out at different gallium composition (x) at optimized temperature of 350 °C. All the films deposited at T{sub s} ≥ 350 °C were polycrystalline chalcopyrite structure, with a preferential orientation of (112), including the graded layer. With increase in x, lattice parameters a and c were observed to decrease. Line scan of the CIGS layer showed intersection of gallium and indium concentrations, revealing the graded nature of the film. Composition dependence of Raman peak for CuInSe{sub 2} (CIS) deposited by CSP was analyzed. Optical transmittance at a wavelength of 800 nm of the film with x = 0 (CIS) (30%) was found lower than that of the film grown with x = 0.82 (CIGS) (50%). Cusp-shape of the resistivity was observed with an increase of x leading to steep rise in resistivity of the films (1.61–71.68 Ω-cm) till x = 0.42 and then decreased to 4.78 Ω-cm at x = 0.82. Carrier concentrations of the films were evaluated in the order of 10{sup 16}–10{sup 19} cm{sup −3} with p-type conductivity. These results indicate that graded CIGS thin films with modulated gallium composition can be prepared by CSP. - Graphical abstract: Display Omitted - Highlights: • Optimization of the spray deposition system for device grade chalcopyrite CIGS films. • Optimized substrate temperature to obtain single-phase CIGS by spray deposition. • Detailed report on compositional dependence of CuInSe{sub 2} (CIS) thin films. • Systematic analysis of the influence of Ga in CIS by spray deposition. • Bowing parameter is extracted from the experiment values.

  9. Structural, optical, and photoluminescence characterization of electron beam evaporated ZnS/CdSe nanoparticles thin films

    Science.gov (United States)

    Mohamed, S. H.; Ali, H. M.

    2011-01-01

    Structural, optical, and photoluminescence investigations of ZnS capped with CdSe films prepared by electron beam evaporation are presented. X-ray diffraction analysis revealed that the ZnS/CdSe nanoparticles films contain cubic cadmium selenide and hexagonal zinc sulfide crystals and the ZnS grain sizes increased with increasing ZnS thickness. The refractive index was evaluated in terms of envelope method, which has been suggested by Swanepoel in the transparent region. The refractive index values were found to increase with increasing ZnS thickness. However, the optical band gap and the extinction coefficient were decreased with increasing ZnS thickness. Photoluminescence (PL) investigations revealed the presence of two broad emission bands. The ZnS thickness significantly influenced the PL intensities.

  10. Rapid quantitative analysis of elemental composition and depth profile of Cu(In,Ga)Se{sub 2} thin solar cell film using laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    In, Jung-Hwan; Kim, Chan-Kyu; Lee, Seok-Hee; Choi, Jang-Hee; Jeong, Sungho, E-mail: shjeong@gist.ac.kr

    2015-03-31

    Laser-induced breakdown spectroscopy (LIBS) is reported as a method for rapid quantitative analysis of elemental composition and depth profile of Cu(In,Ga)Se{sub 2} (CIGS) thin film. A calibration model considering compositional grading over depth was developed and verified with test samples. The results from eight test samples showed that the average concentration of Cu, In, Ga and Se could be predicted with a root mean square error of below 1% and a relative standard deviation of also below 1%. The depth profile of each constituent element of CIGS predicted by LIBS was close to those by Auger electron spectroscopy and secondary ion mass spectrometry. The average ablation depth per pulse during depth profiling was about 100 nm. - Highlights: • LIBS was adopted for quantitative analysis of CIGS thin film. • A calibration model considering compositional grading over depth was developed. • Concentration prediction of CIGS thin film was accurate and precise. • Quantitative depth profiling by LIBS was compared with those by AES and SIMS.

  11. Strategies to reduce the open-circuit voltage deficit in Cu2ZnSn(S,Se)4 thin film solar cells

    Science.gov (United States)

    Kim, Jekyung; Shin, Byungha

    2017-09-01

    Cu2ZnSn(S,Se)4 thin film solar cell has attracted significant attention in thin film solar cell technologies considering its low-cost, non-toxicity, and earth-abundance. However, the highest efficiency still remains at 12.6%, far below the theoretical efficiency of Shockley-Queisser (SQ) limit of around 30%. The limitation behind such shortcoming in the device performance was reported to stem primarily from a high V oc deficit compared to other thin film solar cell technologies such as CdTe or Cu(In,Ga)Se2 (CIGS), whose origins are attributed to the prevalence of band tailing from cation disordering as well as to the high recombination at the interfaces. In this report, systematic studies on the causes of a high V oc deficit and associated remarkable approaches to achieve high V oc have been reviewed, provided with a guidance on the future direction of CZTSSe research in resolving the high V oc deficit issue. [Figure not available: see fulltext.

  12. Preparation and characterization of electrodeposited CuInSe{sub 2} thin films; Preparation et caracterisation des couches minces de CuInSe{sub 2} electrodeposees

    Energy Technology Data Exchange (ETDEWEB)

    Fahoume, M.; Chraibi, F.; Ennaoui, A. [Universite Mohammed 5, Rabat (Morocco). Faculte des Sciences; Fahoume, M.; Aggour, M. [Universite Ibn Tofail, Faculte des Sciences, Kenitra (Morocco)

    1998-01-01

    CuInSe{sub 2} is one of the most promising materials for use in photoelectrochemical as well in photovoltaic solar cells because of its excellent photoactive properties such as high optical absorption coefficient (10`4-10`5 cm`-`1) and good stability. It has been prepared from an aqueous solution containing CuCl{sub 2}, InCl{sub 3}, H{sub 2}SeO{sub 3} complexed by citrate (Na{sub 3}C{sub 6}H{sub 5}O{sub 7}). The kinetics of electrodeposition has been studied by using the rotating disk electrode method (RDE). X-ray diffraction showed the formation of CuInSe{sub 2} films, of chalcopyrite structure, at potentials ranged between -0.95 V and - 1.12 V (vs. SSE). The composition of the deposited films has been studied by energy dispersive analysis of X-rays (EDAX) and Rutherford backscattering spectroscopy (RBS). From the results, it has been found that stoichiometric chalcopyrite CuInSe{sub 2} has been obtained by controlling both composition, deposition potential, solution temperature and pH. (authors) 16 refs.

  13. Non-toxic novel route synthesis and characterization of nanocrystalline ZnS{sub x}Se{sub 1−x} thin films with tunable band gap characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Agawane, G.L., E-mail: agawaneganesh@gmail.com [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Shin, Seung Wook [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Vanalakar, S.A. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Moholkar, A.V. [Electrochemical Mat. Lab., Department of Physics, Shivaji University, Kolhapur 416-004 (India); Gurav, K.V.; Suryawanshi, M.P. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Lee, Jeong Yong [Department of Materials Science and Engineering, KAIST, Daejeon 305-701 (Korea, Republic of); Yun, Jae Ho, E-mail: yunjh92@kier.re.kr [Photovoltaic Research Group, KIER, Jang-Dong, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Kim, Jin Hyeok, E-mail: jinhyeok@chonnam.ac.kr [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

    2014-07-01

    Highlights: • A simple, inexpensive, and non-toxic CBD route is used to deposit ZnS thin films. • The ZnS{sub x}Se{sub 1−x} thin films formation takes place via annealing of ZnS thin films in Se atmosphere. • S/(S + Se) ratio found to be temperature dependent and easy tuning of band gap has been done by Se atom deposition. - Abstract: An environmentally benign chemical bath deposition (CBD) route was employed to deposit zinc sulfide (ZnS) thin films. The CBD-ZnS thin films were further selenized in a furnace at various temperatures viz. 200, 300, 400, and 500 °C and the S/(S + Se) ratio was found to be dependent on the annealing temperature. The effects of S/(S + Se) ratio on the structural, compositional and optical properties of the ZnS{sub x}Se{sub 1−x} (ZnSSe) thin films were investigated. EDS analysis showed that the S/(S + Se) ratio decreased from 0.8 to 0.6 when the film annealing temperature increased from 200 to 500 °C. The field emission scanning electron microscopy and atomic force microscopy studies showed that all the films were uniform, pin hole free, smooth, and adhered well to the glass substrate. The X-ray diffraction study on the ZnSSe thin films showed the formation of the cubic phase, except for the unannealed ZnSSe thin film, which showed an amorphous phase. The X-ray photoelectron spectroscopy revealed Zn-S, Zn-Se, and insignificant Zn-OH bonds formation from the Zn 2p{sub 3/2}, S 2p, Se 3d{sub 5/2}, and O 1s atomic states, respectively. The ultraviolet–visible spectroscopy study showed ∼80% transmittance in the visible region for all the ZnSSe thin films having various absorption edges. The tuning of the band gap energy of the ZnSSe thin films was carried out by selenizing CBD-ZnS thin films, and as the S/(S + Se) ratio decreased from 0.8 to 0.6, the band gap energy decreased from 3.20 to 3.12 eV.

  14. Nanocrystalline Cu{sub 2}ZnSnSe{sub 4} thin films for solar cells application: Microdiffraction and structural characterization

    Energy Technology Data Exchange (ETDEWEB)

    Quiroz, Heiddy P., E-mail: hpquirozg@unal.edu.co; Dussan, A., E-mail: adussanc@unal.edu.co [Departmento de Física, Grupo de Materiales Nanoestructurados y sus Aplicaciones, Universidad Nacional de Colombia, Bogotá 11001 (Colombia)

    2016-08-07

    This work presents a study of the structural characterization of Cu{sub 2}ZnSnSe{sub 4} (CZTSe) thin films by X-ray diffraction (XRD) and microdiffraction measurements. Samples were deposited varying both mass (M{sub X}) and substrate temperature (T{sub S}) at which the Cu and ZnSe composites were evaporated. CZTSe samples were deposited by co-evaporation method in three stages. From XRD measurements, it was possible to establish, with increased Ts, the presence of binary phases associated with the quaternary composite during the material's growth process. A stannite-type structure in Cu{sub 2}ZnSnSe{sub 4} thin films and sizes of the crystallites varying between 30 and 40 nm were obtained. X-ray microdiffraction was used to investigate interface orientations and strain distributions when deposition parameters were varied. It was found that around the main peak, 2ϴ = 27.1°, the Cu{sub 1.8}Se and ZnSe binary phases predominate, which are formed during the subsequent material selenization stage. A Raman spectroscopy study revealed Raman shifts associated with the binary composites observed via XRD.

  15. Optical studies on Zn-doped lead chalcogenide (PbSe){sub 100−x}Zn{sub x} thin films composed of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ashraf, Md. Tanweer [Department of Applied Sciences and Humanities, Jamia Millia Islamia (JMI), New Delhi-25 (India); Salah, Numan A. [Center of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Rafat, M. [Department of Applied Sciences and Humanities, Jamia Millia Islamia (JMI), New Delhi-25 (India); Zulfequar, M. [Department of Physics, Jamia Millia Islamia, New Delhi-25 (India); Khan, Zishan H., E-mail: zishan_hk@yahoo.co.in [Department of Applied Sciences and Humanities, Jamia Millia Islamia (JMI), New Delhi-25 (India)

    2016-08-01

    The effect of laser-Irradiation on the optical properties of Zn-doped PbSe thin films composed of nanoparticles has been studied. Scanning electron microscope (SEM) investigations suggest the formation of nanoparticles of average size of 50 nm for all the studied Zn compositions. XRD studies show that the as-prepared thin films are polycrystalline in nature. The formation of nanoparticles of Zn-doped PbSe has been confirmed by indexing the crystal planes as observed in the XRD spectra. The addition of Zn in (PbSe){sub 100−x}Zn{sub x} thin films result in the blue shift in photoluminescence spectra, this blue shift is associated with the narrowing of the band gap. Optical absorption measurements reveal a direct band gap for the present samples, which decreases on increasing the Zn content. The same trend has also been observed for the samples irradiated with laser. Further, the calculated values of Urbach energy are found to increase with the increase in Zn contents for the as-prepared as well as laser-irradiated samples. All the above observations agree well with the results of optical band gap and suggest that the decrease in band gap may be due to increase in band tails, defects and particle size. - Highlights: • Nanoparticles of Zn doped (PbSe){sub 100−x}Zn{sub x} lead chalcogenides have been synthesized. • Effect of laser irradiation on optical properties of (PbSe){sub 100−x}Zn{sub x} has been studied. • A blue shift in PL spectra is obtained on Zn incorporation.

  16. Ceramic Composite Thin Films

    Science.gov (United States)

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

    2013-01-01

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

  17. Structural phase change and optical band gap bowing in hot wall deposited CdSe{sub x}Te{sub 1-x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Muthukumarasamy, N. [Department of Physics, Coimbatore Institute of Technology, Coimbatore, Tamilnadu (India); Jayakumar, S.; Kannan, M.D.; Balasundaraprabhu, R. [Thin Film Center, PSG College of Technology, Coimbatore, Tamilnadu (India)

    2009-04-15

    CdSe{sub x}Te{sub 1-x} thin films of different compositions have been deposited on glass substrates by hot wall deposition method under conditions very close to thermodynamical equilibrium with minimum loss of material. The structural studies carried out on the deposited films revealed that they are crystalline in nature and exhibit either cubic zinc blende or hexagonal phase or both depending on the composition of the material. The lattice parameter values for both cubic and hexagonal phases have been determined and are observed to vary with composition according to Vegard's law. The optical properties of the deposited CdSe{sub x}Te{sub 1-x} thin films have been studied using transmittance spectra. The spectra shows a sharp fall in transmittance at wavelength corresponding to the band gap of the material. The optical band gap has been determined and found to be direct allowed. The band gap has been observed to strongly depend on film composition. The variation of band gap with composition has been observed to be quadratic in nature exhibiting a bowing behaviour. (author)

  18. Band gap tuning in As40Se53Sb07 thin films by 532 nm laser irradiation: An optical investigation by spectroscopic techniques

    Science.gov (United States)

    Pradhan, Prabhudutta; Naik, R.; Das, N.; Panda, A. K.

    2018-01-01

    The chalcogenide thin films belongs to a special category of important materials due to the unique IR transparency and light induced linear and non linear optical properties change. The optical band gap tuning in thermally evaporated As40Se53Sb07 chalcogenide thin film is being probed under the influence of 532 nm laser illumination. The gradual decrease in transmission and red shift of optical absorption edge with illumination at different time scale is recorded by Fourier transmission infrared spectroscopy. The simultaneous increase in refractive index and absorption coefficient of the illuminated film makes the material as useful candidate for optical switching. The dispersion of refractive index is being analyzed by using Wemple-DiDomenico (WDD) single oscillator model and static refractive index (n0) has also been reported. The exponential decrease of optical band gap with time is attributed to the increase in density of localized states and vacancies. The entire mechanism is explained by the microscopic model in which heteropolar bonds are converted to homopolar ones by the absorption of high energy photons investigated by X-ray photoelectron spectra. The amorphous nature of the studied films was revealed from X-ray diffraction and composition of the film was determined from energy dispersive X-ray analysis. The surface morphology was determined from the scanning electron microscopy. The optical change in absorption coefficient, refractive index, band gap by influence in laser irradiation in such materials may be suitable for optical disc(memory) application for optical time division switch.

  19. Impact of sulfur content on structural and optical properties of Ge20Se80-xSx chalcogenide glasses thin films

    Science.gov (United States)

    Dongol, M.; Elhady, A. F.; Ebied, M. S.; Abuelwafa, A. A.

    2018-04-01

    Chalcogenide system Ge20Se80-xSx (x = 0, 15 and 30%) thin films were prepared by thermal evaporation technique. The amorphous state of the samples was confirmed according to XRD. The structural changes occurring upon replacement Se by S was investigated using Raman spectroscopy. The optical properties of the as-deposited Ge20Se80-xSx thin films have been studied by analysis the transmittance T(λ) measured at room temperature in the wavelength range 200-2500 nm using Swanepoel's method. Urbach energy (Ee) and optical band gap (Eg) were strongly affected by sulfur concentration in the sample. The refractive index evaluated through envelope method was extrapolated by Cauchy dispersion relationship over the whole spectral range. Moreover, the dispersion of refractive index was analyzed in terms of the single-oscillator Wemple-Di Domenico model. The third-order nonlinear susceptibility (χ(3)) and nonlinear refractive index (n2) were calculated and discussed for different Ge20Se80-xSx (x = 0, 15 and 30%).

  20. Weak antilocalization induced by Rashba spin-orbit interaction in layered III-VI compound semiconductor GaSe thin films

    Science.gov (United States)

    Takasuna, Shoichi; Shiogai, Junichi; Matsuzaka, Shunichiro; Kohda, Makoto; Oyama, Yutaka; Nitta, Junsaku

    2017-10-01

    Magnetoconductance (MC) at low temperature was measured to investigate spin-related transport affected by spin-orbit interaction (SOI) in III-VI compound n -type GaSe thin films. Results reveal that MC shows weak antilocalization (WAL). Its temperature and gate voltage dependences reveal that the dominant spin relaxation is governed by the D'yakonov-Perel' mechanism associated with the Rashba SOI. The estimated Rashba SOI strength in GaSe is much stronger than that of III-V compound GaAs quantum wells, although the energy gap and spin split-off band in GaSe closely resemble those in GaAs. The angle dependence of WAL amplitude in the in-plane magnetic field direction is almost isotropic. This isotropy indicates that the strength of the Dresselhaus SOI is negligible compared with the Rashba SOI strength. The SOI effect in n -GaSe thin films differs greatly from those of III-V compound semiconductors and transition-metal dichalcogenides.

  1. Structural and electrical properties of polycrystalline CdSe thin films, before and after irradiation with 6 MeV accelerated electrons

    International Nuclear Information System (INIS)

    Ion, L.; Antohe, V.A.; Tazlaoanu, C.; Antohe, S.; Scarlat, F.

    2004-01-01

    Structural and electrical properties of polycrystalline CdSe thin films irradiated with high-energy electrons are analyzed. The samples were prepared by vacuum deposition of CdSe powder onto optical glass substrate. Their structure and the temperature dependence of the electrical resistance were determined, both before and after irradiation with 6 MeV electrons at fluencies up to 10 16 electrons/cm 2 . There were no measurable changes in the crystalline structure of the films after irradiation. Electrical properties are controlled by the defect level of donor type, possibly a selenium vacancy, with two ionizing states having ionization energies of about 0.40 eV and 0.22 eV, respectively. The major effect of the irradiation is to increase significantly the concentration of these defects. (authors)

  2. Plasma-assisted self-formation of nanotip arrays on the surface of Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zimin, Sergey P.; Mokrov, Dmitry A. [Yaroslavl State University (Russian Federation); Gorlachev, Egor S.; Amirov, Ildar I.; Naumov, Viktor V. [Institute of Physics and Technology, Russian Academy of Sciences, Yaroslavl (Russian Federation); Gremenok, Valery F. [Scientific-Practical Materials Research Center, NAS of Belarus, Minsk (Belarus); Bente, Klaus [Applied Mineralogy, University Tuebingen (Germany); Kim, Woo Y. [Fusion Research Center, Hoseo University, Asan-City (Korea, Republic of)

    2017-06-15

    In this paper, we report on the phenomenon of nanostructure self-formation on the surface of Cu(In,Ga)Se{sub 2} (CIGS) thin films during inductively coupled argon plasma treatment with its duration varied from 10 to 120 s. The initial films were grown on glass substrates using the selenization technique. During the CIGS film surface treatment in the high-density low-pressure radio-frequency inductively coupled argon plasma there took place a formation of arrays of uniform vertical nanostructures, which shape with increasing processing duration changed from nanocones to nanorods and back to nanocones. A model of the nanotip plasma-assisted self-formation associated with the implementation of micromasking and vapor-liquid-solid mechanisms involving metallic In-Ga (In-Ga-Cu) liquid alloy droplets is proposed. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. High absorption coefficients of the CuSb(Se,Te2 and CuBi(S,Se2 alloys enable high-efficient 100 nm thin-film photovoltaics

    Directory of Open Access Journals (Sweden)

    Chen Rongzhen

    2017-01-01

    Full Text Available We demonstrate that the band-gap energies Eg of CuSb(Se,Te2 and CuBi(S,Se2 can be optimized for high energy conversion in very thin photovoltaic devices, and that the alloys then exhibit excellent optical properties, especially for tellurium rich CuSb(Se1−xTex2. This is explained by multi-valley band structure with flat energy dispersions, mainly due to the localized character of the Sb/Bi p-like conduction band states. Still the effective electron mass is reasonable small: mc ≈ 0.25m0 for CuSbTe2. The absorption coefficient α(ω for CuSb(Se1−xTex2 is at ħω = Eg + 1 eV as much as 5–7 times larger than α(ω for traditional thin-film absorber materials. Auger recombination does limit the efficiency if the carrier concentration becomes too high, and this effect needs to be suppressed. However with high absorptivity, the alloys can be utilized for extremely thin inorganic solar cells with the maximum efficiency ηmax ≈ 25% even for film thicknesses d ≈ 50 − 150 nm, and the efficiency increases to ∼30% if the Auger effect is diminished.

  4. High absorption coefficients of the CuSb(Se,Te)2 and CuBi(S,Se)2 alloys enable high-efficient 100 nm thin-film photovoltaics

    Science.gov (United States)

    Chen, Rongzhen; Persson, Clas

    2017-06-01

    We demonstrate that the band-gap energies Eg of CuSb(Se,Te)2 and CuBi(S,Se)2 can be optimized for high energy conversion in very thin photovoltaic devices, and that the alloys then exhibit excellent optical properties, especially for tellurium rich CuSb(Se1-xTex)2. This is explained by multi-valley band structure with flat energy dispersions, mainly due to the localized character of the Sb/Bi p-like conduction band states. Still the effective electron mass is reasonable small: mc ≈ 0.25m0 for CuSbTe2. The absorption coefficient α(ω) for CuSb(Se1-xTex)2 is at ħω = Eg + 1 eV as much as 5-7 times larger than α(ω) for traditional thin-film absorber materials. Auger recombination does limit the efficiency if the carrier concentration becomes too high, and this effect needs to be suppressed. However with high absorptivity, the alloys can be utilized for extremely thin inorganic solar cells with the maximum efficiency ηmax ≈ 25% even for film thicknesses d ≈ 50 - 150 nm, and the efficiency increases to ˜30% if the Auger effect is diminished.

  5. 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...

  6. High efficiency Cu(In,Ga)Se{sub 2} thin film solar cells without intermediate buffer layers

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, K.; Wiesner, H.; Asher, S.; Niles, D.; Bhattacharya, R.N.; Keane, J.; Contreras, M.A.; Noufi, R. [National Renewable Energy Lab., Golden, CO (United States). Electronic Materials and Devices Div.

    1998-09-01

    The nature of the interface between CuInGaSe{sub 2} (CIGS) and the chemical bath deposited CdS layer has been investigated. The authors show that heat-treating the absorbers in Cd- or Zn-containing solutions in the presence of ammonium hydroxide sets up an interfacial reaction with the possibility of an ion exchange occurring between Cd and Cu. The characteristics of devices made in this manner suggest that the reaction generates a thin, n-doped region in the absorber. The authors suggest that this aspect might be more important than the CdS layer in the formation of the junction. It is quite possible that the CdS/CuInSe{sub 2} device is a buried, shallow junction with a CdS window layer, rather than a heterojunction between CdS and CIGS. The authors use these ideas to develop methods for fabricating diodes without CdS or Cd.

  7. Fabrication of Cu(In,Ga)Se2 thin films by a combination of mechanochemical and screen-printing/sintering processes

    International Nuclear Information System (INIS)

    Wada, T.; Matsuo, Y.; Nomura, S.; Nakamura, Y.; Miyamura, A.; Chiba, Y.; Konagai, M.; Yamada, A.

    2006-01-01

    We prepared fine Cu(In,Ga)Se 2 (CIGS) powder suitable for screen printing using a mechanochemical process. Particulate precursors were deposited in a thin layer by a screen-printing technique, the remaining organic solvent was removed from the screen-printed CIGS film and finally the porous precursor layer was sintered into a dense polycrystalline film by atmospheric-pressure firing. The crystal structure of the film was analyzed by X-ray diffraction and the microstructure was observed in a SEM. The thickness of the film was 5-10 μm with a grain size of about 2 μm. The films were also observed in a TEM. The grain size of the as-prepared powder was less than 1 μm; however, it enlarged to 2-3 μm after firing at 575 C under a Se ambient. Preliminary CIGS solar cells with our standard Al grid/B-doped ZnO/i-ZnO/ CdS/CIGS/Mo/soda-lime glass structure were fabricated. An efficiency of 2.7%, a V oc of 0.325 V, a J sc of 28.3 mA/cm 2 and a FF of 0.295 was obtained. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  8. Electrochemical synthesis of photosensitive nano-nest like CdSe{sub 0.6}Te{sub 0.4} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, Surendra K., E-mail: surendrashinde.phy@gmail.com [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S (India); Thombare, Jagannath V. [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S (India); Dubal, Deepak P. [Department of Electrochemistry, Technische Universität Chemnitz Institut für Chemie, Straße der Nationen 62, D-09111 Chemnitz (Germany); Fulari, Vijay J., E-mail: vijayfulari@gmail.com [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S (India)

    2013-10-01

    Polycrystalline CdSe{sub 0.6}Te{sub 0.4} thin films were deposited on stainless steel and ITO coated glass (ITO) substrates by using simple and inexpensive electrodeposition method. CdSe{sub 0.6} Te{sub 0.4} films are characterized by different characterization techniques such as X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR) and contact angle measurement. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure. FE-SEM studies reveal that the entire substrate surface is covered with CdSe{sub 0.6} Te{sub 0.4} nano-nest. Formation of CdSe{sub 0.6}Te{sub 0.4} compound was confirmed from the FTIR studies. Optical absorption study shows the presence of direct transition and a considerable band gap, E{sub g} = 1.7 eV. Surface wettability with solid–liquid interface showed hydrophilic nature with water contact angle 57° (<90°). Further photovoltaic activity of CdSe{sub 0.6}Te{sub 0.4} films were studied by forming the photoelectrochemical cell having CdSe{sub 0.6}Te{sub 0.4}/1 M (Na{sub 2}S + S + NaOH)/C cell configuration. The efficiency and fill factor of these PEC cells are found to be 0.64% and 0.49 respectively.

  9. Dataset demonstrating the modeling of a high performance Cu(In,GaSe2 absorber based thin film photovoltaic cell

    Directory of Open Access Journals (Sweden)

    Md. Asaduzzaman

    2017-04-01

    Full Text Available The physical data of the semiconductor materials used in the design of a CIGS absorber based thin film photovoltaic cell have been presented in this data article. Besides, the values of the contact parameter and operating conditions of the cell have been reported. Furthermore, by conducting the simulation with data corresponding to the device structure: soda-lime glass (SLG substrate/Mo back-contact/CIGS absorber/CdS buffer/intrinsic ZnO/Al-doped ZnO window/Al-grid front-contact, the solar cell performance parameters such as open circuit voltage (Voc, short circuit current density Jsc, fill factor (FF, efficiency (η, and collection efficiency ηc have been analyzed.

  10. Application of a substrate bias to control the droplet density on Cu(In,Ga)Se{sub 2} thin films grown by Pulsed Electron Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rampino, S. [IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Pattini, F., E-mail: rampino@imem.cnr.it [IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Malagù, C.; Pozzetti, L. [Department of Physics and Earth Sciences, University of Ferrara, Via Saragat, 1-44122 Ferrara (Italy); Stefancich, M. [LENS Laboratory, Masdar Institute of Science and Technology, Masdar City, PO Box 54224, Abu Dhabi (United Arab Emirates); Bronzoni, M. [IMEM-CNR Institute, Parco Area delle Scienze 37/A, 43124 Parma (Italy)

    2014-07-01

    One of the main shortcomings in the fabrication of thin-film solar cells by pulsed high-energy deposition techniques (i.e. Pulsed Laser Deposition or Pulsed Electron Deposition — PED), is the presence of a significant number of particulates on the film surface. This affects the morphological properties of the cell active layers and, ultimately, the performance of the final device. To reduce the density of these defects, we deposited a Cu(In,Ga)Se{sub 2} (CIGS) thin film by PED and studied the effect on the film morphology when a DC bias was applied between the substrate and the target. Our results show that a negative substrate voltage, comprised between 0 and − 300 V, can not only reduce the droplet density on the CIGS film surface of about one order of magnitude with respect to the standard unbiased case (from 6 × 10{sup 5} to 5 × 10{sup 4} cm{sup −2}), but also lower the maximum particulate size and the surface smoothness. When a positive voltage is applied, we observed that a significant increase in the droplet surface density (up to 10{sup 8} cm{sup −2}) occurs. The abrupt change in the preferred crystal orientation (switching from (112) to (220)/(204) by applying negative and positive biases, respectively) is also a direct consequence of the applied DC voltage. These results confirm that the external DC bias could be used as an additional parameter to control the physical properties of thin films grown by PED. - Highlights: • Cu(In,Ga)Se{sub 2} (CIGS) films were grown by Pulsed Electron Deposition (PED). • Positive and negative DC biases were applied between the target and the substrate. • The droplet density can be reduced by one order of magnitude by DC negative bias. • Chemical composition and grain orientation of CIGS are influenced by the DC bias. • The DC bias can be an additional parameter of PED for controlling the film properties.

  11. Reliable wet-chemical cleaning of natively oxidized high-efficiency Cu(In,Ga)Se{sub 2} thin-film solar cell absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, Jascha [Renewable Energies, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Potsdam Institute for Climate Impact Research (PIK), 14473 Potsdam (Germany); Lehmann, Sebastian, E-mail: sebastian.lehmann@ftf.lth.se [Renewable Energies, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Solid State Physics, Lund University, Box 118, S-22100 Lund (Sweden); Lauermann, Iver; Rissom, Thorsten; Kaufmann, Christian A.; Lux-Steiner, Martha Ch. [Renewable Energies, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Bär, Marcus, E-mail: marcus.baer@helmholtz-berlin.de [Renewable Energies, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Institut für Physik und Chemie, Brandenburgische Technische Universität Cottbus-Senftenberg, Platz der Deutschen Einheit 1, 03046 Cottbus (Germany); Sadewasser, Sascha, E-mail: sascha.sadewasser@inl.int [Renewable Energies, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga (Portugal)

    2014-12-21

    Currently, Cu-containing chalcopyrite-based solar cells provide the highest conversion efficiencies among all thin-film photovoltaic (PV) technologies. They have reached efficiency values above 20%, the same performance level as multi-crystalline silicon-wafer technology that dominates the commercial PV market. Chalcopyrite thin-film heterostructures consist of a layer stack with a variety of interfaces between different materials. It is the chalcopyrite/buffer region (forming the p-n junction), which is of crucial importance and therefore frequently investigated using surface and interface science tools, such as photoelectron spectroscopy and scanning probe microscopy. To ensure comparability and validity of the results, a general preparation guide for “realistic” surfaces of polycrystalline chalcopyrite thin films is highly desirable. We present results on wet-chemical cleaning procedures of polycrystalline Cu(In{sub 1-x}Ga{sub x})Se{sub 2} thin films with an average x = [Ga]/([In] + [Ga]) = 0.29, which were exposed to ambient conditions for different times. The hence natively oxidized sample surfaces were etched in KCN- or NH{sub 3}-based aqueous solutions. By x-ray photoelectron spectroscopy, we find that the KCN treatment results in a chemical surface structure which is – apart from a slight change in surface composition – identical to a pristine as-received sample surface. Additionally, we discover a different oxidation behavior of In and Ga, in agreement with thermodynamic reference data, and we find indications for the segregation and removal of copper selenide surface phases from the polycrystalline material.

  12. Investigations on electron beam evaporated Cu(In{sub 0.85}Ga{sub 0.15})Se{sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Venkatachalam, M.; Kannan, M.D.; Prasanna, S.; Jayakumar, S.; Balasundaraprabhu, R. [Thin Film Center, Department of Physics, PSG College of Technology, Coimbatore (India); Muthukumarasamy, N. [Department of Physics, Coimbatore Institute of Technology, Coimbatore (India); Saroja, M. [Department of Electronics, Erode Arts College, Erode (India)

    2009-09-15

    CIGS bulk with composition of CuIn{sub 0.85}Ga{sub 0.15}Se{sub 2} was synthesized by direct reaction of elemental copper, indium, gallium and selenium. CIGS thin films were then deposited onto well-cleaned glass substrates using the prepared bulk alloy by electron beam deposition method. The structural properties of the deposited films were studied using X-ray diffraction technique. The as-deposited CIGS films were found to be amorphous. On annealing, the films crystallized with a tetragonal chalcopyrite structure. An intermediate Cu-rich phase precipitated at 200 C and dissociated at higher annealing temperatures. Average grain size calculated from the XRD spectra indicated that the films had a nano-crystalline structure and was further corroborated by AFM analysis of the sample surface. The chemical constituents present in the deposited CIGS films were identified using energy dispersive X-ray analysis. CIGS based solar cells were then fabricated on molybdenum and ITO coated glass substrates and the efficiencies have been evaluated. (author)

  13. Quantum-dot light-emitting diodes utilizing CdSe /ZnS nanocrystals embedded in TiO2 thin film

    Science.gov (United States)

    Kang, Seung-Hee; Kumar, Ch. Kiran; Lee, Zonghoon; Kim, Kyung-Hyun; Huh, Chul; Kim, Eui-Tae

    2008-11-01

    Quantum-dot (QD) light-emitting diodes (LEDs) are demonstrated on Si wafers by embedding core-shell CdSe /ZnS nanocrystals in TiO2 thin films via plasma-enhanced metallorganic chemical vapor deposition. The n-TiO2/QDs /p-Si LED devices show typical p-n diode current-voltage and efficient electroluminescence characteristics, which are critically affected by the removal of QD surface ligands. The TiO2/QDs /Si system we presented can offer promising Si-based optoelectronic and electronic device applications utilizing numerous nanocrystals synthesized by colloidal solution chemistry.

  14. Role of heat treatment on structural and optical properties of thermally evaporated Ga{sub 10}Se{sub 81}Pb{sub 9} chalcogenide thin films

    Energy Technology Data Exchange (ETDEWEB)

    El-Sebaii, A.A., E-mail: ahmedelsebaii@yahoo.com [Department of Physics, Faculty of Science, King Abdulaziz University, 80203 Jeddah 21589 (Saudi Arabia); Khan, Shamshad A. [Department of Physics, St. Andrews College, Gorakhpur 273001 (India); Al-Marzouki, F.M.; Faidah, A.S.; Al-Ghamdi, A.A. [Department of Physics, Faculty of Science, King Abdulaziz University, 80203 Jeddah 21589 (Saudi Arabia)

    2012-08-15

    Amorphous chalcogenides, based on Se, have become materials of commercial importance and were widely used for optical storage media. The present work deals with the structural and optical properties of Ga{sub 10}Se{sub 81}Pb{sub 9} ternary chalcogenide glass prepared by melt quenching technique. The glass transition, crystallization and melting temperatures of the synthesized glass were measured by non-isothermal DSC measurements at a constant heating rate of 30 K/min. Thin films of thickness 4000 A were prepared by thermal evaporation techniques on glass/Si (1 0 0) wafer substrate. These thin films were thermally annealed for two hours at three different annealing temperatures of 345, 360 and 375 K, which were in between the glass transition and crystallization temperatures of the Ga{sub 10}Se{sub 81}Pb{sub 9} glass. The structural, morphological and optical properties of as-prepared and annealed thin films were studied. Analysis of the optical absorption data showed that the rules of the non-direct transitions predominate. It was also found that the optical band gap decreases while the absorption coefficient, refractive index and extinction coefficient increase with increasing the annealing temperature. Due to the higher values of absorption coefficient and annealing dependence of the optical band gap and optical constants, the investigated material could be used for optical storage. - Highlights: Black-Right-Pointing-Pointer Annealing effect on structure and optical band gap has been investigated. Black-Right-Pointing-Pointer The amorphous nature has been verified by x-ray diffraction and DSC measurements. Black-Right-Pointing-Pointer Thermal annealing causes a decrease in optical band gap in Ga{sub 10}Se{sub 81}Pb{sub 9} thin films. Black-Right-Pointing-Pointer The decrease in optical band gap can be interpreted on the basis of amorphous-crystalline phase transformation. Black-Right-Pointing-Pointer Optical absorption data showed that the rules of the non

  15. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  16. Strength, stiffness, and microstructure of Cu(In,Ga)Se{sub 2} thin films deposited via sputtering and co-evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Shi; Jang, Dongchan; Greer, Julia R., E-mail: jrgreer@caltech.edu [Division of Applied Science and Engineering, California Institute of Technology, 1200 E California Blvd., Pasadena, California 91125 (United States); Lee, Jiun-Haw [Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, No. 1, Sec 4 Roosevelt, Taipei 10617, Taiwan (China); Liu, Chee-Wee [Department of Electrical Engineering, National Taiwan University, No 1, Sec 4 Roosevelt, Taipei 10617, Taiwan (China); Shieh, Jia-Min; Shen, Chang-Hong; Wu, Tsung-Ta [National Nano Device Laboratories, Hsinchu Science Park, No. 26, Prosperity Road I, Hsinchu 30078, Taiwan (China)

    2014-07-07

    This work examines Cu(In,Ga)Se{sub 2} thin films fabricated by (1) selenization of pre-sputtered Cu-In-Ga and (2) co-evaporation of each constituent. The efficiency disparity between films deposited via these two methods is linked to differences in morphology and microstructure. Atomic force microscopy and scanning electron microscopy show that selenized films have rougher surfaces and poor adhesion to molybdenum back contact. Transmission electron microscopy and electron energy loss spectroscopy revealed multiple voids near the Mo layer in selenized films and a depletion of Na and Se around the voids. Residual stresses in co-evaporated films were found to be ∼1.23 GPa using wafer curvature measurements. Uniaxial compression experiments on 500 nm-diameter nanopillars carved out from co-evaporated films revealed the elastic modulus of 70.4 ± 6.5 GPa. Hertzian contact model applied to nanoindentation data on selenized films revealed the indentation modulus of 68.9 ± 12.4 GPa, which is in agreement with previous reports. This equivalence of the elastic moduli suggests that microstructural differences manifest themselves after the yield point. Typical plastic behavior with two distinct failure modes is observed in the extracted stress-strain results, with the yield strength of 640.9 ± 13.7 MPa for pillars that failed by shearing and 1100.8 ± 77.8 MPa for pillars that failed by shattering.

  17. Photonic sintering of thin film prepared by dodecylamine capped CuIn{sub x}Ga{sub 1−x}Se{sub 2} nanoparticles for printed photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Manjeet, E-mail: msitbhu@gmail.com; Jiu, Jinting; Sugahara, Tohru; Suganuma, Katsuaki

    2014-08-28

    In this paper, we report solution phase large scale synthesis of monodisperse phase pure CuIn{sub x}Ga{sub 1−x}Se{sub 2} (CIGS) nanoparticles by using dodecylamine as solvent and dispersant. Various compositions of CIGS nanoparticles with different Ga content are synthesized by simply adding different amounts of Ga precursors. The band gap of CIGS nanoparticles can be tuned by changing Ga content. Effort is given to understand the formation pathway of CIGS phase so as to make the synthesis easier for the desired product. High intensity pulsed light technique, which provides extreme local heating, is used to sinter the thin film prepared using these nanoparticles on a Mo–glass surface. A uniformly conductive and dense CIGS film can be prepared by adjusting the energy of light and exposure time. The high intensity light irradiation of the CIGS film leads to diffusion of smaller CIGS nanoparticles to form a particle with larger grain size and thus enables sintering of particles without using high temperature processing. - Highlights: • Large scale synthesis of CuIn{sub x}Ga{sub 1−x}Se{sub 2} (CIGS) is reported. • Dodecylamine is used as surfactant and solvent. • CIGS phase formation mechanism is described. • High intensity pulsed light technique is used to sinter the CIGS film.

  18. Bandgap engineering by substitution of S by Se in nanostructured ZnS{sub 1-x}Se{sub x} thin films grown by soft chemical route for nontoxic optoelectronic device applications

    Energy Technology Data Exchange (ETDEWEB)

    Sadekar, Harishchandra K [Thin Film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, Maharashtra (India); Department of Physics, Arts, Commerce and Science College, Sonai 414105, Maharashtra (India); Ghule, Anil Vithal [Department of Nanotechnology, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, Maharashtra (India); Sharma, Ramphal [Thin Film and Nanotechnology Laboratory, Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad 431004, Maharashtra (India)

    2011-05-05

    Highlights: > ZnS{sub 1-x}Se{sub x} (x = 0 to 1) thin films are successfully deposited on glass substrates by soft chemical route. > Structural, optical and electrical properties are studied. > Change in band gap, crystallite size and resistivity is noted with change in S:Se ratio. > Wide band gap material (ZnS{sub 1-x}Se{sub x}) is useful for photosensor and solar cell applications. > It utilizes whole visible light spectrum and is a best alternative to conventionally used toxic CdS. - Abstract: Thin films of nanostructured ZnS{sub 1-x}Se{sub x} with optimized growth parameters were prepared by soft chemical route on glass substrates. Ammonia free precursors were used at 80 deg. C constant bath temperature. The ratio of sulphur to selenium was changed continuously by changing the composition x (0-1), while atomic concentration of zinc was kept constant. Structure, composition and surface morphology of as-deposited films were characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM), atomic force microscopy (AFM) respectively. XRD studies revealed that as-deposited films were nanostructured in nature with cubic zinc blended structure. It was further observed that the preferred orientations are along (1 1 1) plane and crystallite size decreased with increase in the value of x. SEM and AFM images revealed that films were uniform and pinhole free. The optical band gap (E{sub g}) was calculated from the observed transmittance spectra by Urbach method. It was found that the band gap varied linearly from 3.71 to 2.70 eV, as composition x varies 0-1. The electrical properties' study revealed that the decrease in resistivity and increase in photosensitivity, as composition x varied 0-1. The observed interesting properties of ZnS{sub 1-x}Se{sub x} thin films justified their significance in optoelectronic device fabrication and applications, and as an environment friendly alternative to the commonly used toxic

  19. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  20. Impact of sodium on the secondary phases and current pathway in Cu{sub 2}(Zn,Sn)Se{sub 4} thin film solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yi-Cheng, E-mail: ielinyc@cc.ncue.edu.tw [Department of Mechatronics Engineering, National Changhua University of Education, Changhua, Taiwan (China); Lai, Chien-Mu [Department of Mechatronics Engineering, National Changhua University of Education, Changhua, Taiwan (China); Hsu, Hung-Ru [Green Energy & Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China)

    2017-05-01

    In this study, we investigated the influence of Na content on secondary phases and current pathway in Cu{sub 2}(Zn,Sn)Se{sub 4} (CZTSe) thin film solar cells with the following structure: Ti/Mo:Na/Mo/CZTSe/CdS/i-ZnO/ZnO:Al/Al. The application of Na-doped Mo target as a source of sodium. Experimental results demonstrate that increasing the Na content leads to an increase in the quantity of secondary phase SnSe{sub 2} on the surface of the absorber layer; however, it did not appear to affect the secondary phases of Cu{sub 2}SnSe{sub 3} (CTSe) or ZnSe. Excessive quantities of Na were shown to have an adverse effect on device efficiency. Our results using conductive atomic force microscopy (C-AFM) revealed that an increase in the quantity of secondary phase SnSe{sub 2} can shift the current pathway on the surface of CZTSe from CZTSe grain boundaries (GBs) to the SnSe{sub 2} grains. The role of secondary phase SnSe{sub 2} of the CZTSe acted as a channel for the current flow, which results in high leakage current and low device efficiency. - Highlights: • Increasing the Na content leads to an increase in the quantity of secondary phase SnSe{sub 2}. • An increase of secondary phase SnSe{sub 2} can shift the current pathway from CZTSe grain boundaries to the SnSe{sub 2} grains. • The secondary phase SnSe{sub 2} acted as a channel for the current flow, which results in high leakage current.

  1. Influence of growth temperature of transparent conducting oxide layer on Cu(In,Ga)Se2 thin-film solar cells

    International Nuclear Information System (INIS)

    Cho, Dae-Hyung; Chung, Yong-Duck; Lee, Kyu-Seok; Park, Nae-Man; Kim, Kyung-Hyun; Choi, Hae-Won; Kim, Jeha

    2012-01-01

    We have studied the influence of growth temperature (T G ) in the deposition of an indium tin oxide (ITO) transparent conducting oxide layer on Cu(In,Ga)Se 2 (CIGS) thin-film solar cells. The ITO films were deposited on i-ZnO/glass and i-ZnO/CdS/CIGS/Mo/glass substrates using radio-frequency magnetron sputtering at various T G up to 350 °C. Both the resistivity of ITO and the interface quality of CdS/CIGS strongly depend on T G . For a T G ≤ 200 °C, a reduction in the series resistance enhanced the solar cell performance, while the p–n interface of the device was found to become deteriorated severely at T G > 200 °C. CIGS solar cells with ITO deposited at T G = 200 °C showed the best performance in terms of efficiency.

  2. Thin film tritium dosimetry

    Science.gov (United States)

    Moran, Paul R.

    1976-01-01

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

  3. Compositional and electrical properties of line and planar defects in Cu(In,Ga)Se{sub 2} thin films for solar cells - a review

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Ras, Daniel; Schmidt, Sebastian S.; Schaefer, Norbert; Kavalakkatt, Jaison; Rissom, Thorsten; Unold, Thomas; Mainz, Roland; Weber, Alfons [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109, Berlin (Germany); Kirchartz, Thomas [Forschungszentrum Juelich, Institut fuer Energie- und Klimaforschung (IEK-5), Photovoltaik, 52428, Juelich (Germany); Simsek Sanli, Ekin; Aken, Peter A. van [Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569, Stuttgart (Germany); Ramasse, Quentin M. [SuperSTEM Laboratory, SciTech Daresbury Campus, Keckwick Lane, Daresbury, WA4 4AD (United Kingdom); Kleebe, Hans-Joachim [Technische Universitaet Darmstadt, Institut fuer Angewandte Geowissenschaften, Schnittspahnstrasse 9, 64287, Darmstadt (Germany); Azulay, Doron; Balberg, Isaac; Millo, Oded [Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem, 91904 (Israel); Cojocaru-Miredin, Oana [RWTH Aachen, Physikalisches Institut IA, Sommerfeldstr. 14, 52074, Aachen (Germany); Barragan-Yani, Daniel; Albe, Karsten [Technische Universitaet Darmstadt, FG Materialmodellierung, Jovanka-Bontschits-Str. 2, 64287, Darmstadt (Germany); Haarstrich, Jakob; Ronning, Carsten [Institut fuer Festkoerperphysik, Friedrich Schiller Universitaet Jena, Max-Wien-Platz 1, 07743, Jena (Germany)

    2016-05-15

    The present review gives an overview of the various reports on properties of line and planar defects in Cu(In,Ga)(S,Se){sub 2} thin films for high-efficiency solar cells. We report results from various analysis techniques applied to characterize these defects at different length scales, which allow for drawing a consistent picture on structural and electronic defect properties. A key finding is atomic reconstruction detected at line and planar defects, which may be one mechanism to reduce excess charge densities and to relax deep-defect states from midgap to shallow energy levels. On the other hand, nonradiative Shockley-Read-Hall recombination is still enhanced with respect to defect-free grain interiors, which is correlated with substantial reduction of luminescence intensities. Comparison of the microscopic electrical properties of planar defects in Cu(In,Ga)(S,Se){sub 2} thin films with two-dimensional device simulations suggest that these defects are one origin of the reduced open-circuit voltage of the photovoltaic devices. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Application of femtosecond laser ablation inductively coupled plasma mass spectrometry for quantitative analysis of thin Cu(In,Ga)Se{sub 2} solar cell films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seokhee [School of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Gonzalez, Jhanis J. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Applied Spectra Inc., 46665 Fremont Boulevard, Fremont, CA 94538 (United States); Yoo, Jong H. [Applied Spectra Inc., 46665 Fremont Boulevard, Fremont, CA 94538 (United States); Chirinos, Jose R. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Facultad de Ciencias, Universidad Central de Venezuela, Caracas 1041A (Venezuela, Bolivarian Republic of); Russo, Richard E. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Applied Spectra Inc., 46665 Fremont Boulevard, Fremont, CA 94538 (United States); Jeong, Sungho, E-mail: shjeong@gist.ac.kr [School of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of)

    2015-02-27

    This work reports that the composition of Cu(In,Ga)Se{sub 2} (CIGS) thin solar cell films can be quantitatively predicted with high accuracy and precision by femtosecond laser ablation-inductively coupled plasma-mass spectrometry (fs-LA-ICP-MS). It is demonstrated that the results are strongly influenced by sampling conditions during fs-laser beam (λ = 1030 nm, τ = 450 fs) scanning on the CIGS surface. The fs-LA-ICP-MS signals measured at optimal sampling conditions generally provide a straight line calibration with respect to the reference concentrations measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). The concentration ratios predicted by fs-LA-ICP-MS showed high accuracy, to 95–97% of the values measured with ICP-OES, for Cu, In, Ga, and Se elements. - Highlights: • Laser ablation inductively coupled plasma mass spectrometry of thin film is reported. • Concentration ratio prediction with a confidence level of 95–97% is achieved. • Quantitative determination of composition is demonstrated.

  5. Evidence for surface-generated photocurrent in (Bi,Sb)2Se3and(Bi,Sb)2Te3 thin films

    Science.gov (United States)

    Pan, Yu; Richardella, Anthony; Yao, Bing; Lee, Joon Sue; Flanagan, Thomas; Kandala, Abhinav; Samarth, Nitin; Yeats, Andrew; Mintun, Peter; Awschalom, David

    2015-03-01

    Illumination with circularly polarized light is known produce a helicity-dependent photocurrent in topological insulators such as Bi2Se3 [e.g. Nature Nanotech. 7, 96 (2012)]. However, the exact origin of this effect is still unclear since it is observed with photons well above the bulk band gap. We report measurements of the polarization-dependent photocurrent in a series of (Bi,Sb)2Se3 thin films with different carrier concentrations and find that the photocurrent is enhanced as we increase the population of the surface states. This finding is supported by a study of helicity-dependent photocurrents in back-gated (Bi,Sb)2Te3 thin films, where the chemical potential is varied electrostatically. By illuminating our samples at different wavelengths, we show that the helicity-dependent photocurrent is enhanced when the photon energy approaches the energy difference between the lowest and first excited (unoccupied) topological surface states. This leads us to attribute the helicity-dependent photocurrent in topological insulators to optical excitations between these two spin-textured surface states. We will also discuss experiments imaging the spatial variation of these helicity-dependent photocurrents. This work is supported by ONR.

  6. Compositional and electrical properties of line and planar defects in Cu(In,Ga)Se2 thin films for solar cells - a review

    International Nuclear Information System (INIS)

    Abou-Ras, Daniel; Schmidt, Sebastian S.; Schaefer, Norbert; Kavalakkatt, Jaison; Rissom, Thorsten; Unold, Thomas; Mainz, Roland; Weber, Alfons; Kirchartz, Thomas; Simsek Sanli, Ekin; Aken, Peter A. van; Ramasse, Quentin M.; Kleebe, Hans-Joachim; Azulay, Doron; Balberg, Isaac; Millo, Oded; Cojocaru-Miredin, Oana; Barragan-Yani, Daniel; Albe, Karsten; Haarstrich, Jakob; Ronning, Carsten

    2016-01-01

    The present review gives an overview of the various reports on properties of line and planar defects in Cu(In,Ga)(S,Se) 2 thin films for high-efficiency solar cells. We report results from various analysis techniques applied to characterize these defects at different length scales, which allow for drawing a consistent picture on structural and electronic defect properties. A key finding is atomic reconstruction detected at line and planar defects, which may be one mechanism to reduce excess charge densities and to relax deep-defect states from midgap to shallow energy levels. On the other hand, nonradiative Shockley-Read-Hall recombination is still enhanced with respect to defect-free grain interiors, which is correlated with substantial reduction of luminescence intensities. Comparison of the microscopic electrical properties of planar defects in Cu(In,Ga)(S,Se) 2 thin films with two-dimensional device simulations suggest that these defects are one origin of the reduced open-circuit voltage of the photovoltaic devices. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. High efficiency bifacial Cu2ZnSnSe4 thin-film solar cells on transparent conducting oxide glass substrates

    Directory of Open Access Journals (Sweden)

    Jung-Sik Kim

    2016-09-01

    Full Text Available In this work, transparent conducting oxides (TCOs have been employed as a back contact instead of Mo on Cu2ZnSnSe4 (CZTSe thin-film solar cells in order to examine the feasibility of bifacial Cu2ZnSn(S,Se4 (CZTSSe solar cells based on a vacuum process. It is found that the interfacial reaction between flourine doped tin oxide (FTO or indium tin oxide (ITO and the CZTSe precursor is at odds with the conventional CZTSe/Mo reaction. While there is no interfacial reaction on CZTSe/FTO, indium in CZTSe/ITO was significantly diffused into the CZTSe layers; consequently, a SnO2 layer was formed on the ITO substrate. Under bifacial illumination, we achieved a power efficiency of 6.05% and 4.31% for CZTSe/FTO and CZTSe/ITO, respectively.

  8. Optical waveguide based on amorphous Er{sup 3+}-doped Ga-Ge-Sb-S(Se) pulsed laser deposited thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nazabal, V., E-mail: virginie.nazabal@univ-rennes1.f [Sciences Chimiques de Rennes (SCR), UMR CNRS 6226, Equipe Verres et Ceramiques, Universite de Rennes 1, Rennes (France); Nemec, P. [Department of General and Inorganic Chemistry and Research Center, Faculty of Chemical Technology, University of Pardubice, Legions Sq. 565, 53210, Pardubice (Czech Republic); Jurdyc, A.M [Laboratoire de Physico-Chimie des Materiaux Luminescents (LPCML), UMR CNRS 5620, Universite Claude Bernard-Lyon 1, Villeurbanne (France); Zhang, S.; Charpentier, F. [Sciences Chimiques de Rennes (SCR), UMR CNRS 6226, Equipe Verres et Ceramiques, Universite de Rennes 1, Rennes (France); Lhermite, H. [IETR-Microelectronique, UMR CNRS 6251, Universite de Rennes 1, 35042 Rennes (France); Charrier, J. [FOTON, UMR 6082-ENSSAT, UMR CNRS 6251, Universite de Rennes 1, 35042 Rennes (France); Guin, J.P. [LARMAUR, UMR CNRS 6251, Universite de Rennes 1, 35042 Rennes (France); Moreac, A. [Institut de Physique de Rennes, UMR CNRS 6251, Universite de Rennes 1, 35042 Rennes (France); Frumar, M. [Department of General and Inorganic Chemistry and Research Center, Faculty of Chemical Technology, University of Pardubice, Legions Sq. 565, 53210, Pardubice (Czech Republic); Adam, J.-L. [Sciences Chimiques de Rennes (SCR), UMR CNRS 6226, Equipe Verres et Ceramiques, Universite de Rennes 1, Rennes (France)

    2010-06-30

    Amorphous chalcogenide films play a motivating role in the development of integrated planar optical circuits due to their potential functionality in near infrared (IR) and mid-IR spectral regions. More specifically, the photoluminescence of rare earth ions in amorphous chalcogenide films can be used in laser and amplifier devices in the IR spectral domain. The aim of the present investigation was to optimize the deposition conditions for the fabrication of undoped and Er{sup 3+} doped sulphide and selenide thin films with nominal composition Ga{sub 5}Ge{sub 20}Sb{sub 10}S(Se){sub 65} or Ga{sub 5}Ge{sub 23}Sb{sub 5}S{sub 67} by pulsed laser deposition (PLD). The study of compositional, morphological and structural characteristics of the layers was realized by scanning electron microscopy-energy dispersive spectroscopy, atomic force microscopy and Raman spectroscopy analyses, respectively. Some optical properties (transmittance, index of refraction, optical band gap, etc.) of prepared chalcogenide films and optical losses were investigated as well. The clear identification of near-IR photoluminescence of Er{sup 3+} ions was obtained for both selenide and sulphide films. The decay of the {sup 4}I{sub 13/2} {yields} {sup 4}I{sub 15/2} transition at 1.54 {mu}m in Er{sup 3+} doped Ga{sub 5}Ge{sub 20}Sb{sub 10}S{sub 65} PLD sulphide films was studied to assess the effects of film thickness, rare earth concentration and multilayer PLD deposition on their spectroscopic properties.

  9. Origin of localized states in zinc-blende ZnCdSe thin films and the influence on carrier relaxation of self-assembled ZnTe/ZnCdSe quantum dots

    International Nuclear Information System (INIS)

    Lee, Ling; Dai, Yue-Ru; Yang, Chu-Shou; Fan, Wen-Chung; Chou, Wu-Ching

    2015-01-01

    Highlights: • The localized emission in zinc-blende ZnCdSe is induced by excess selenium. • An optimized growth is demonstrated as the VI/II ratio approaches unity. • Size-independent lifetimes are observed in ZnTe/ZnCdSe quantum dots. • Localized electrons in the capping layer dominate size-independent lifetimes. - Abstract: This study discovered the origin of deep level emission in zinc-blende ZnCdSe thin films grown by molecular beam epitaxy, in which a localization behavior was noticed. Pronounced deep level emission observed in films grown under a VI/II ratio of 1.74 (Se-accumulated regime) could be suppressed by a lower VI/II ratio of 1.04 (intermediate regime) and 0.74 (metal-rich regime). Hence the localized states could be correlated to excess selenium accumulated at the growth surface. The localized states also influence the carrier relaxation process of self-assembled ZnTe quantum dots embedded in a ZnCdSe matrix. Once quantum dots surmount the wetting layer, localized electrons in the capping layer dominate the type-II transition and exhibit size-independent lifetimes

  10. Chemical bath deposited Zn(Se,OH){sub x} on Cu(In,Ga)(S,Se){sub 2} for high efficiency thin film solar cells: growth kinetics, electronic properties, device performance and loss analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ennaoui, A.; Weber, M. [Hahn-Meitner-Institut Berlin GmbH (Germany). Bereich Physikalische Chemie; Saad, M.; Harneit, W.; Lux-Steiner, M.C. [Hahn-Meitner-Institut Berlin GmbH (Germany). Bereich Festkoerperphysik; Karg, F. [Siemens Solar GmbH, Muenchen (Germany)

    2000-02-21

    Zn(Se,OH){sub x} thin films were grown on Cu(In,Ga)(S,Se){sub 2} (CIGSS) substrate by chemical bath technique. The initial formation and subsequent development of the CIGSS/Zn(Se,OH){sub x} interface are studied by XPS photoemission spectroscopy. Changes in the In 4d and Zn 3d core lines are used to directly determine the CIGSS/Zn(Se,OH){sub x} heterojunction valence band discontinuity and the consequent heterojunction band diagram. For device optimization the thickness and good surface coverage were controlled by XPS-UPS photoemission spectroscopy. A Zn(Se,OH){sub x} thickness below 10 nm has been found to be optimum for achieving a homogeneous and compact film on CIGSS. A remarkably high active area efficiency up to 15.7% (total area efficiency 13.26% with open circuit voltage (V{sub oc}) up to 565.74 mV, a fill factor (FF) of 71% and a short-circuit photocurrent density (J{sub ph}) greater than 33.01 mA/cm{sup 2}) are obtained. The internal parameters, such as the saturation currents, the series resistance R{sub s} and shunt resistance R{sub sh} are calculated. Major losses in these cells are due to the significant influence of the series resistance R{sub s} on the fill factor. (orig.)

  11. Annealing enhancement effect by light illumination on proton irradiated Cu(In, Ga)Se2 thin-film solar cells

    International Nuclear Information System (INIS)

    Kawakita, Shirou; Imaizumi, Mitsuru; Matsuda, Sumio; Yamaguchi, Masafumi; Kushiya, Katsumi; Ohshima, Takeshi; Itoh, Hisayoshi

    2002-01-01

    In this paper, we investigated the high radiation tolerance of copper indium gallium di-selenide (CIGS) thin-film solar cells by conducting in situ measurements of short circuit current and open circuit voltage of CIGS thin-film solar cells during and after proton irradiation under short circuit condition. We found that the annealing rate of proton-induced defects in CIGS thin-film solar cells under light illumination with an AM0 solar simulator is higher than that under dark conditions. The activation energy of proton-induced defects in the CIGS thin-film solar cells with (without) light illumination is 0.80 eV (0.92 eV), which implies on enhanced defect annealing rate in CIGS thin-film solar cells due to minority-carrier injection. (author)

  12. Structural properties of Bi{sub 2−x}Mn{sub x}Se{sub 3} thin films grown via molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Babakiray, Sercan; Johnson, Trent A.; Borisov, Pavel; Holcomb, Mikel B.; Lederman, David, E-mail: david.lederman@mail.wvu.edu [Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Marcus, Matthew A. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Tarafder, Kartick [Department of Physics, BITS-Pilani Hyderabad Campus, Secunderabad, Andhra Pradesh 500078 (India)

    2015-07-28

    The effects of Mn doping on the structural properties of the topological insulator Bi{sub 2}Se{sub 3} in thin film form were studied in samples grown via molecular beam epitaxy. Extended x-ray absorption fine structure measurements, supported by density functional theory calculations, indicate that preferential incorporation occurs substitutionally in Bi sites across the entire film volume. This finding is consistent with x-ray diffraction measurements which show that the out of plane lattice constant expands while the in plane lattice constant contracts as the Mn concentration is increased. X-ray photoelectron spectroscopy indicates that the Mn valency is 2+ and that the Mn bonding is similar to that in MnSe. The expansion along the out of plane direction is most likely due to weakening of the Van der Waals interactions between adjacent Se planes. Transport measurements are consistent with this Mn{sup 2+} substitution of Bi sites if additional structural defects induced by this substitution are taken into account.

  13. Study of optoelectronic properties of thin film solar cell materials Cu2ZnSn(S,Se)4 using multiple correlative spatially-resolved spectroscopy techniques

    Science.gov (United States)

    Chen, Qiong

    Containing only earth abundant and environmental friendly elements, quaternary compounds Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe 4 (CZTSe) are considered as promising absorber materials for thin film solar cells. The best record efficiency for this type of thin film solar cell is now 12.6%. As a promising photovoltaic (PV) material, the electrical and optical properties of CZTS(Se) have not been well studied. In this work, an effort has been made to understand the optoelectronic and structural properties, in particular the spatial variations, of CZTS(Se) materials and devices by correlating multiple spatially resolved characterization techniques with sub-micron resolution. Micro-Raman (micro-Raman) spectroscopy was used to analyze the chemistry compositions in CZTS(Se) film; Micro-Photoluminescence (micro-PL) was used to determine the band gap and possible defects. Micro-Laser-Beam-Induced-Current (micro-LBIC) was used to examine the photo-response of CZTS(Se) solar cell in different illumination conditions. Micro-reflectance was used to estimate the reflectance loss. And Micro-I-V measurement was used to compare important electrical parameters from CZTS(Se) solar cells with different device structure or absorber compositions. Scanning electron microscopy and atomic force microscopy were used to characterize the surface morphology. Successfully integrating and correlating these techniques was first demonstrated during the course of this work in our laboratory, and this level of integration and correlation has been rare in the field of PV research. This effort is significant not only for this particular project and also for a wide range of research topics. Applying this approach, in conjunction with high-temperature and high-excitation-power optical spectroscopy, we have been able to reveal the microscopic scale variations among samples and devices that appeared to be very similar from macroscopic material and device characterizations, and thus serve as a very powerful tool

  14. Effects of water vapor introduction during Cu(In1-xGax)Se2 deposition on thin film properties and solar cell performance

    International Nuclear Information System (INIS)

    Ishizuka, S.; Sakurai, K.; Yamada, A.; Matsubara, K.; Shibata, H.; Kojima, T.; Niki, S.; Yonemura, M.; Nakamura, S.; Nakanishi, H.

    2006-01-01

    The effects of water vapor introduction during the growth of Cu(In 1-x Ga x )Se 2 , specifically CuInSe 2 (CISe), Cu(In,Ga)Se 2 (CIGSe), and CuGaSe 2 (CGSe) thin films were studied. We have developed thus far a novel technique to improve CIGSe (x∝0.5) cell performance by means of water vapor introduction during CIGSe deposition. In this study, we have examined the effectiveness of water vapor introduction for other x-compositions (CISe and CGSe). Variations in the electrical properties observed in CIGSe (x∝0.5), that is, increasing hole density and conductivity with water vapor introduction, were also observed in CISe and CGSe. Water vapor introduction affected solar cell performance as well; open circuit voltages, short circuit current densities, and efficiencies were improved. The improvements in cell performance are thought to be related to annihilation of donor defects arising from Se-vacancies by incorporation of oxygen from the water vapor. In addition to this, the sodium content in the CIGSe layers was found to depend on the partial pressure of water vapor during deposition. This result suggests that the improvement mechanism is also related with the so-called 'Na-effects'. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  15. AC conductivity and dielectric properties of amorphous GexSb40-xSe60 thin films

    International Nuclear Information System (INIS)

    Atyia, H.E.; Farid, A.M.; Hegab, N.A.

    2008-01-01

    Measurements of AC conductivity and dielectric properties have been made for chalcogenide film samples of Ge x Sb 40-x Se 60 (with x=0, 10 and 20 at%) at different temperatures (303-393 K) and various frequencies (10 2 -10 5 Hz). It was found that the AC conductivity obeys the law σ(ω, T)=Aω s . The exponent s 1 and dielectric loss ε 2 were found to decrease with frequency and increase with temperature. The maximum barrier height W M was calculated from dielectric measurements according to the Guintini equation. It was found that the obtained value of W m agrees with that proposed by the theory of hopping of charge carriers over potential barrier as suggested by Elliott in case of chalcogenide glasses. The density of localized states N(E F ) has also been calculated for the studied compositions. The effect of decreasing the Sb content at the expense of the Ge content was investigated for the obtained results of the studied parameters

  16. Influence of laser wavelength on the laser induced breakdown spectroscopy measurement of thin CuIn1−xGaxSe2 solar cell films

    International Nuclear Information System (INIS)

    Kim, Chan Kyu; In, Jung Hwan; Lee, Seok Hee; Jeong, Sungho

    2013-01-01

    Laser induced breakdown spectroscopy (LIBS) measurement of thin CuIn x Ga 1−x Se 2 (CIGS) films (1.2–1.9 μm) with varying Ga to In ratios was carried out using the fundamental (1064 nm) and second harmonic (532 nm) wavelength Nd:YAG lasers (τ = 5 ns, spot diameter = 150 μm, top-hat profile) in air. The concentration ratios of Ga to In, x Ga ≡ Ga/(Ga + In), of the CIGS samples ranged from 0.027 to 0.74 for which the band gap varied nearly proportionally to x Ga from 0.96 to 1.42. It was found that the LIBS signal of 1064 nm (1.17 eV) wavelength laser was significantly influenced by x Ga , whereas that of the 532 nm (2.34 eV) laser was consistent for all values of x Ga . The observed dependency of the LIBS signal intensity on the laser wavelength was attributed to the large difference of photon energy of the two wavelengths that changed the absorption of incident laser energy by the film. The 532 nm wavelength was found to be advantageous for multi-shot analysis that enabled depth profile analysis of the thin CIGS films and for improving measurement precision by averaging the multi-shot LIBS spectra. - Highlights: • The ablation characteristics of CIGS solar cell films change drastically with laser wavelength. • The LIBS signal intensity of 1064 nm wavelength laser depends strongly on Ga concentration. • Multi-shot LIBS analysis using a 532 nm laser is more advantageous for accuracy and consistency

  17. Influence of post-treatment on properties of Cu(In{sub ,}Ga)Se{sub 2} thin films deposited by RF magnetron sputtering using a quaternary single target for photovoltaic devices

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sung Hee; Choi, Soon Ja; Chung, Chee Won, E-mail: cwchung@inha.ac

    2014-11-03

    The deposition of Cu(In,Ga)Se{sub 2} (CIGS) thin films has been performed by one-step RF sputtering using a single quaternary target and followed by sulfurization to incorporate S into CIGS films. The effect of sulfurization temperature and time on the properties of the films was studied. The sulfurized Cu(In,Ga)(Se,S){sub 2} (CIGSeS) films show that the chalcopyrite peaks shifted to high diffraction angles and the CuS and InS second phases could be formed at low sulfurization temperature. These indicate possible incorporation of S into the films. The formation and disappearance of these second phases depended on the sulfurization temperature and time. The band gap increased with increasing sulfurization temperature and time because of the shift of the absorption edge due to the increase of S/(S + Se) ratio. It was revealed that the resistivity of the as-deposited CIGS film increased after sulfurization while the carrier concentration and mobility decreased. It is believed that the sulfurization process of CIGS films can be utilized as a method to control the properties of the films. - Highlights: • Development of sputtering process of CIGS thin films using single quaternary target • Effect of sulfurization temperature and time on the properties of CIGS films • Application of sulfurization process to improve the properties of CIGS films • Successful transformation of CIGS films to chalcopyrite structure through post-sulfirization.

  18. In-situ sol-gel synthesis and thin film deposition of Cu(In,Ga)(S,Se)2 solar cells

    International Nuclear Information System (INIS)

    Oliveira, L.; Lyubenova, T.; Marti, R.; Fraga, D.; Rey, A.; Carda, J.; Kozhukharov, V.

    2013-01-01

    Full text: Nowadays chalcogenide-based solar cells, like Cu(In,Ga)Se 2 , are competitive in the photovoltaic market, due to its improved performances like higher efficiency (20,3%), long-time stability and excellent durability. In addition, CIGS stand out with an exceptionally high absorption coefficient (more than; 105/cm for 1.5eV) and higher energy photons. These properties make it an excellent candidate as an absorber material for large scale production of photovoltaic modules for building-integrated applications. Traditional methods of manufacture involve vacuum processes including co-evaporation and sputtering that increase production costs. With the aim to lower the expenses by using non-vacuum solution processes we propose an ‘in-situ’ sol-gel synthesis route and direct thin film deposition in the same production step. As a result, we achieved better stoichiometric control, simplicity in the procedure and cost reduction. In this work we describe a procedure to obtain CIGS absorber layer by soft chemistry technique and further deposition onto different substrates. Preparation parameters like precursors, chemical composition, solvents, thermal treatment factors (temperature, time, and atmosphere) were detailed studied. Finally, the resulting materials were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDAX), UV-VIS Spectroscopy among others.; key words: sol-gel synthesis, thin film deposition, photovoltaic modules, solar cells

  19. Thin films and nanomaterials

    International Nuclear Information System (INIS)

    Jayakumar, S.; Kannan, M.D.; Prasanna, S.

    2012-01-01

    The objective of this book is to disseminate the most recent research in Thin Films, Nanomaterials, Corrosion and Metallurgy presented at the International Conference on Advanced Materials (ICAM 2011) held in PSG College of Technology, Coimbatore, India during 12-16 December 2011. The book is a compilation of 113 chapters written by active researchers providing information and critical insights into the recent advancements that have taken place. Important new applications are possible today in the fields of microelectronics, opto-electronics, metallurgy and energy by the application of thin films on solid surfaces. Recent progress in high vacuum technology and new materials has a remarkable effect in thin film quality and cost. This has led to the development of new single or multi-layered thin film devices with diverse applications in a multitude of production areas, such as optics, thermal barrier coatings and wear protections, enhancing service life of tools and to protect materials against thermal and atmospheric influence. On the other hand, thin film process techniques and research are strongly related to the basic research activities in nano technology, an increasingly important field with countless opportunities for applications due to the emergence of new properties at the nanoscale level. Materials and structures that are designed and fabricated at the nano scale level, offer the potential to produce new devices and processes that may enhance efficiencies and reduce costs in many areas, as photovoltaic systems, hydrogen storage, fuel cells and solar thermal systems. In the book, the contributed papers are classified under two sections i) thin films and ii) nanomaterials. The thin film section includes single or multi layer conducting, insulating or semiconducting films synthesized by a wide variety of physical or chemical techniques and characterized or analyzed for different applications. The nanomaterials section deals with novel or exciting materials

  20. Aspects of electron-phonon interactions with strong forward scattering in FeSe Thin Films on SrTiO3 substrates

    Science.gov (United States)

    Wang, Y.; Nakatsukasa, K.; Rademaker, L.; Berlijn, T.; Johnston, S.

    2016-05-01

    Mono- and multilayer FeSe thin films grown on SrTiO3 and BiTiO3 substrates exhibit a greatly enhanced superconductivity over that found in bulk FeSe. A number of proposals have been advanced for the mechanism of this enhancement. One possibility is the introduction of a cross-interface electron-phonon (e-ph) interaction between the FeSe electrons and oxygen phonons in the substrates that is peaked in the forward scattering (small {q}) direction due to the two-dimensional nature of the interface system. Motivated by this, we explore the consequences of such an interaction on the superconducting state and electronic structure of a two-dimensional system using Migdal-Eliashberg (ME) theory. This interaction produces not only deviations from the expectations of conventional phonon-mediated pairing but also replica structures in the spectral function and density of states, as probed by angle-resolved photoemission spectroscopy, scanning tunneling microscopy/spectroscopy, and quasiparticle interference imaging. We also discuss the applicability of ME theory for a situation where the e-ph interaction is peaked at small momentum transfer and in the FeSe/STO system.

  1. Thin Film Microbatteries

    International Nuclear Information System (INIS)

    Dudney, Nancy J.

    2008-01-01

    Thin film batteries are built layer by layer by vapor deposition. The resulting battery is formed of parallel plates, much as an ordinary battery construction, just much thinner. The figure (Fig. 1) shows an example of a thin film battery layout where films are deposited symmetrically onto both sides of a supporting substrate. The full stack of films is only 10 to 15 (micro)m thick, but including the support at least doubles the overall battery thickness. When the support is thin, the entire battery can be flexible. At least six companies have commercialized or are very close to commercializing such all-solid-state thin film batteries and market research predicts a growing market and a variety of applications including sensors, RFID tags, and smarter cards. In principle with a large deposition system, a thin film battery might cover a square meter, but in practice, most development is targeting individual cells with active areas less than 25 cm 2 . For very small battery areas, 2 , microfabrication processes have been developed. Typically the assembled batteries have capacities from 0.1 to 5 mAh. The operation of a thin film battery is depicted in the schematic diagram (Fig. 2). Very simply, when the battery is allowed to discharge, a Li + ion migrates from the anode to the cathode film by diffusing through the solid electrolyte. When the anode and cathode reactions are reversible, as for an intercalation compound or alloy, the battery can be recharged by reversing the current. The difference in the electrochemical potential of the lithium determines the cell voltage. Most of the thin films used in current commercial variations of this thin film battery are deposited in vacuum chambers by RF and DC magnetron sputtering and by thermal evaporation onto unheated substrates. In addition, many publications report exploring a variety of other physical and chemical vapor deposition processes, such as pulsed laser deposition, electron cyclotron resonance sputtering, and

  2. Heat treatment and thickness-dependent electrical study of Se{sub 50}Te{sub 20}S{sub 30} thin film

    Energy Technology Data Exchange (ETDEWEB)

    Abd-Elrahman, M.I.; Hafiz, M.M.; Qasem, Ammar; Abdel-Rahim, M.A. [Assiut University, Physics Department, Faculty of Science, Assiut (Egypt)

    2016-08-15

    Chalcogenide Se{sub 50}Te{sub 20}S{sub 30} thin film of different thickness was deposited using thermal evaporation technique. The thermogram of the chalcogenide bulk Se{sub 50}Te{sub 20}S{sub 30} was obtained using a differential scanning calorimetry (DSC) with heating rate of 7.5 K/min. The glass transition temperature T{sub g}, crystallization temperature T{sub c} and peak crystallization temperature T{sub p} were identified. The X-ray diffraction (XRD) examination indicates the amorphous nature of the as-deposited film and polycrystalline structure of the thermal annealed ones. The dark electrical resistivity (ρ) measurements were taken in temperature range (300-500 K) and thickness range (200-450 nm). Analysis of the electrical resistivity results revealed two types of conduction mechanisms: conduction due to extended states in the temperature range (T > T{sub c}) and variable range hopping in the temperature range (T < T{sub c}). The effect of the heat treatment and thickness on the density of localized states at the Fermi level N(E{sub F}) and hopping parameters were studied. (orig.)

  3. Determination and analysis of optical constants for Ge{sub 15}Se{sub 60}Bi{sub 25} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Atyia, H.E., E-mail: hebaelghrip@hotmail.com [Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt); Physics Department, Faculty of Applied Medical Science at Turabah, Taif University, Turabah (Saudi Arabia); Hegab, N.A. [Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo (Egypt)

    2014-12-01

    Thin films of Ge{sub 15}Se{sub 60}Bi{sub 25} were deposited, at room temperature, on glass substrates by thermal evaporation technique. The optical reflectance and transmittance of amorphous Ge{sub 15}Se{sub 60}Bi{sub 25} films were measured at normal incident in the wavelength range (500–2500 nm). The optical constants, the refractive index n and the absorption index k, were determined and analyzed according to different approximate methods using the transmittance measurements only and accurate method using the transmittance and reflectance measurements. Analysis of the absorption index k data reveal the values of the optical band gap E{sub g}{sup opt}, the width of tails E{sub e} and the type of transitions. Some optical parameters such as, high frequency dielectric constant ε{sub ∞}, dispersion parameters (oscillation energy E{sub s} and the dispersion energy E{sub d}), real and imaginary parts of complex dielectric constant (ε{sub 1} and ε{sub 2}) and dielectric parameters (dissipation factor tan δ, dielectric relaxation time τ, the volume and surface energy loss functions) were estimated by analyzing the refractive index n data.The relative errors for all optical parameters depending on different approximate methods were identified and discussed.

  4. Optical thin film deposition

    International Nuclear Information System (INIS)

    Macleod, H.A.

    1979-01-01

    The potential usefulness in the production of optical thin-film coatings of some of the processes for thin film deposition which can be classified under the heading of ion-assisted techniques is examined. Thermal evaporation is the process which is virtually universally used for this purpose and which has been developed to a stage where performance is in almost all respects high. Areas where further improvements would be of value, and the possibility that ion-assisted deposition might lead to such improvements, are discussed. (author)

  5. Thin Film Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K.

    1998-11-19

    The motivation to develop thin film technologies dates back to the inception of photovoltaics. It is an idea based on achieving truly low-cost photovoltaics appropriate for mass production and energy significant markets. The key to the idea is the use of pennies worth of active materials. Since sunlight carries relatively little energy in comparison with combustion-based energy sources, photovoltaic (PV) modules must be cheap to produce energy that can be competitive. Thin films are presumed to be the answer to that low-cost requirement. But how cheap do they have to be? The following is an oversimplified analysis that allows some insight into this question.

  6. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  7. Effect of heat treatments and window layer processing on the characteristics of CuInGaSe{sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, K.; Contreras, M.A.; Tuttle, J.R. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    Interaction between chemical bath deposited CdS and ZnO window layers are a focus of this paper. Low temperature anneals were used to follow the changes at the interface. Optical absorption spectra show that CdS and ZnO intermix upon annealing. When applied to ZnO/CdS/CuInGaSe{sub 2} thin film solar cells, changes in the short and long wavelength response were observed. The latter is attributed to an increase in the energy gap of the absorber by diffusion of S. The interdiffusion is shown to increase the short wavelength collection, and hence the current density of the devices. Photoluminescence data provides some indication of the quality of the interface.

  8. Defect study of Cu2ZnSn(SxSe1-x)4 thin film absorbers using photoluminescence and modulated surface photovoltage spectroscopy

    Science.gov (United States)

    Lin, Xianzhong; Ennaoui, Ahmed; Levcenko, Sergiu; Dittrich, Thomas; Kavalakkatt, Jaison; Kretzschmar, Steffen; Unold, Thomas; Lux-Steiner, Martha Ch.

    2015-01-01

    Defect states in Cu2ZnSn(SxSe1-x)4 thin films with x = 0.28, 0.36, and 1 were studied by combining photoluminescence (PL) and modulated surface photovoltage (SPV) spectroscopy. A single broad band emission in the PL spectra was observed and can be related to quasi-donor-acceptor pair transitions. The analysis of the temperature dependent quenching of the PL band (x = 0.28, 0.36, and 1) and SPV (x = 0.28) signals resulted in activation energies below 150 meV for PL and about 90 and 300 meV for SPV. Possible intrinsic point defects that might be associated with these observed activation energies are discussed.

  9. The formation of CuInSe{sub 2}-based thin-film solar cell absorbers from alternative low-cost precursors

    Energy Technology Data Exchange (ETDEWEB)

    Jost, S.

    2008-01-18

    This work deals with real-time investigations concerning the crystallisation process of CuInSe{sub 2}-based thin-film solar cell absorbers while annealing differently produced and composed ''low-cost'' precursors. Various types of precursors have been investigated concerning their crystallisation behaviour. Three groups of experiments have been performed: (i) Investigations concerning the crystallisation process of the quaternary chalcopyrite Cu(In,Al)Se{sub 2} and Cu(In,Al)S{sub 2}, (ii) investigations concerning the formation process of the compound semiconductor CuInSe{sub 2} from electroplated precursors, and (iii) investigations concerning the crystallisation of Cu(In,Ga)Se{sub 2} using precursors with thermally evaporated indium. A specific sample surrounding has been constructed, which enables to perform time-resolved angle-dispersive X-ray powder diffraction experiments during the annealing process of precursor samples. A thorough analysis of subsequently recorded diffraction patterns using the Rietveld method provides a detailed knowledge about the semiconductor crystallisation process while annealing. Based on these fundamental investigations, conclusions have been drawn concerning an adaptation of the precursor deposition process in order to optimise the final solar cell results. The investigations have shown, that one class of electroplated precursors shows a crystallisation behaviour identical to the one known for vacuum-deposited precursors. The investigations concerning the crystallisation process of the quaternary chalcopyrite Cu(In,Al)Se{sub 2} revealed, that the chalcopyrite forms from the ternary selenide (Al,In){sub 2}Se{sub 3} and Cu{sub 2}Se at elevated process temperatures. This result is used to explain the separation of the absorber layer into an aluminum-rich and an indium-rich chalcopyrite phase, which has been observed at processed Cu(In,Al)Se{sub 2} absorbers from several research groups. In addition, differences

  10. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

    Presents an account of the fundamental structure-property relations in oxide thin films. This title discusses the functional properties of thin film oxides in the context of applications in the electronics and renewable energy technologies.

  11. NMR characterization of thin films

    Science.gov (United States)

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

    2010-06-15

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

  12. NMR characterization of thin films

    Science.gov (United States)

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

    2008-11-25

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

  13. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  14. Selective inorganic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.L.F.; Weisenbach, L.A.; Anderson, M.T. [Sandia National Laboratories, Albuquerque, NM (United States)] [and others

    1995-05-01

    This project is developing inorganic thin films as membranes for gas separation applications, and as discriminating coatings for liquid-phase chemical sensors. Our goal is to synthesize these coatings with tailored porosity and surface chemistry on porous substrates and on acoustic and optical sensors. Molecular sieve films offer the possibility of performing separations involving hydrogen, air, and natural gas constituents at elevated temperatures with very high separation factors. We are focusing on improving permeability and molecular sieve properties of crystalline zeolitic membranes made by hydrothermally reacting layered multicomponent sol-gel films deposited on mesoporous substrates. We also used acoustic plate mode (APM) oscillator and surface plasmon resonance (SPR) sensor elements as substrates for sol-gel films, and have both used these modified sensors to determine physical properties of the films and have determined the sensitivity and selectivity of these sensors to aqueous chemical species.

  15. Behavior of Electrochemically Prepared CuInSe2 as Photovoltaic Absorber in thin Film Solar Cells

    International Nuclear Information System (INIS)

    Guillen, C; Martinez, M.A.; Dona, J. M.; Herrero, J; Gutierrez, M. T.

    2000-01-01

    Two different objectives have been pursued in the present investigation: 1) optimization of the CuInSe, preparation parameters from electrodeposited precursors, and 2) evaluation of their photovoltaic behavior by preparing and enhancing Mo/CuInSe,/CdS/TCO devices. When Cu-In-Se precursors are directly electrodeposited, the applied potential fit is essential to improve the photovoltaic performance. Suitable absorbers have been also obtained by evaporating an In layer onto electrodeposited Cu-Se precursors. In this case, the substrate temperature during evaporation determines the CuInSe, quality. Similar results have been reached by substituting typical Mo-coated glass substrates by flexible Mo foils. Different TCO tested (ZnO and ITO) have been found equivalent as front electrical contact in the devices. Solar cell performance can be improved by annealing in air at 200 degree centigree. (Author) 46 refs

  16. The Influence of Interfaces on Properties of Thin-Film Inorganic Structural Isomers Containing SnSe-NbSe2 Subunits.

    Science.gov (United States)

    Alemayehu, Matti B; Falmbigl, Matthias; Ta, Kim; Johnson, David C

    2015-04-28

    Inorganic isomers ([SnSe]1+δ)m(NbSe2)n([SnSe]1+δ)p(NbSe2)q([SnSe]1+δ)r(NbSe2)s where m, n, p, q, r, and s are integers and m + p + r = n + q + s = 4 were prepared using the modulated elemental reactant technique. This series of all six possible isomers provides an opportunity to study the influence of interface density on properties while maintaining the same unit cell size and composition. As expected, all six compounds were observed to have the same atomic compositions and an almost constant c-axis lattice parameter of ≈4.90(5) nm, with a slight trend in the c-axis lattice parameter correlated with the different number of interfaces in the isomers: two, four and six. The structures of the constituents in the ab-plane were independent of one another, confirming the nonepitaxial relationship between them. The temperature dependent electrical resistivities revealed metallic behavior for all the six compounds. Surprisingly, the electrical resistivity at room temperature decreases with increasing number of interfaces. Hall measurements suggest this results from changes in carrier concentration, which increases with increasing thickness of the thickest SnSe block in the isomer. Carrier mobility scales with the thickness of the thickest NbSe2 block due to increased interfacial scattering as the NbSe2 blocks become thinner. The observed behavior suggests that the two constituents serve different purposes with respect to electrical transport. SnSe acts as a charge donor and NbSe2 acts as the charge transport layer. This separation of function suggests that such heterostructures can be designed to optimize performance through choice of constituent, layer thickness, and layer sequence. A simplistic model, which predicts the properties of the complex isomers from a weighted sum of the properties of building blocks, was developed. A theoretical model is needed to predict the optimal compound for specific properties among the many potential compounds that can be prepared.

  17. Electronic defect study on low temperature processed Cu(In,Ga)Se2 thin-film solar cells and the influence of an Sb layer

    International Nuclear Information System (INIS)

    Van Puyvelde, L; Lauwaert, J; Devulder, W; Detavernier, C; Vrielinck, H; Tempez, A; Nishiwaki, S; Pianezzi, F; Tiwari, A N

    2015-01-01

    A way to lower the manufacturing cost of Cu(In,Ga)Se 2 (CIGS) thin-film solar cells is to use flexible polymer substrates instead of rigid glass. Because such substrates require lower temperature during absorber deposition, the grain growth of the absorber layer can be hindered which leads to a lower cell performance. Partial compensation of this efficiency loss might be accomplished by growing the absorber in the presence of Sb, which is reported to promote grain growth. In this work CIGS solar cells, deposited on glass substrates, at a reduced substrate temperature with a thin Sb layer (7, 12 nm) on top of the Mo contact are investigated. The diffusion profile of Sb is measured with plasma profiling time of flight mass spectrometry. The beneficial effect of Sb on efficiency and grain size is shown in quantum efficiency measurements and with scanning electron microscopy, respectively. Electric spectroscopy is used to explore the possible effects on the defect structure, more in particular on the dominant shallow acceptor. Admittance spectra exhibit a capacitance step to the geometric capacitance plateau at low temperature (5–60 K). Analyzing this capacitance step, we obtained a good estimate of the activation energy of the intrinsic defects that provide the p-type conductivity of the CIGS absorber. The measurements did not show a change in the nature of the dominant acceptor upon Sb treatment. (paper)

  18. Nonvolatile memory thin film transistors using CdSe/ZnS quantum dot-poly(methyl methacrylate) composite layer formed by a two-step spin coating technique

    Science.gov (United States)

    Chen, Ying-Chih; Huang, Chun-Yuan; Yu, Hsin-Chieh; Su, Yan-Kuin

    2012-08-01

    The nonvolatile memory thin film transistors (TFTs) using a core/shell CdSe/ZnS quantum dot (QD)-poly(methyl methacrylate) (PMMA) composite layer as the floating gate have been demonstrated, with the device configuration of n+-Si gate/SiO2 insulator/QD-PMMA composite layer/pentacene channel/Au source-drain being proposed. To achieve the QD-PMMA composite layer, a two-step spin coating technique was used to successively deposit QD-PMMA composite and PMMA on the insulator. After the processes, the variation of crystal quality and surface morphology of the subsequent pentacene films characterized by x-ray diffraction spectra and atomic force microscopy was correlated to the two-step spin coating. The crystalline size of pentacene was improved from 147.9 to 165.2 Å, while the degree of structural disorder was decreased from 4.5% to 3.1% after the adoption of this technique. In pentacene-based TFTs, the improvement of the performance was also significant, besides the appearances of strong memory characteristics. The memory behaviors were attributed to the charge storage/discharge effect in QD-PMMA composite layer. Under the programming and erasing operations, programmable memory devices with the memory window (Δ Vth) = 23 V and long retention time were obtained.

  19. Deep absorption band in Cu(In,Ga)Se{sub 2} thin films and solar cells observed by transparent piezoelectric photothermal spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shirakata, Sho; Atarashi, Akiko [Faculty of Engineering, Ehime University, Matsuyama 790-8577 (Japan); Yagi, Masakazu [Kagawa National College of Technology, Mitoyo-shi 769-1192 (Japan)

    2015-06-15

    The photo-acoustic spectroscopy (PAS) using a transparent piezoelectric photo-thermal (Tr-PPT) method was carried out on Cu(In,Ga)Se{sub 2} (CIGS) thin films (both CIGS/Mo/SLG and CdS/CIGS/Mo/SLG) and solar cells (ZnO/CdS/CIGS/Mo/SLG). Using the Tr-PPT method, the high background absorption in the below gap region observed in both a microphone and a conventional transducer PAS spectra was strongly reduced. This high background absorption came from the CIGS/Mo interface. This result proves that the Tr-PPT PAS is the surface sensitive method. In the below-band region, a bell-shape deep absorption band has been observed at 0.76 eV, in which a full-width at the half-maximum value was 70-120 meV. This deep absorption band was observed for both CdS/CIGS/Mo/SLG and ZnO/CdS/CIGS/Mo/SLG structures. The peak energy of the absorption band was independent of the alloy composition for 0.25≤Ga/III≤0.58. Intensity of the PA signal was negatively correlated to the Na concentration at the CIGS film surface. The origin of the 0.76 eV peak is discussed with relation to native defects such as a Cu-vacancy-related defect (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Enhanced electrical properties of pulsed laser-deposited CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films via processing control

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Yeon Hwa; Mohanty, Bhaskar Chandra; Cho, Yong Soo [Department of Materials Science and Engineering, Yonsei University, Seoul (Korea, Republic of)

    2010-12-15

    Polycrystalline CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films were prepared on soda-lime glass substrates using pulsed laser deposition (PLD) with various process parameters such as laser energy, repetition rate and substrate temperature. It was confirmed that there existed a limited laser energy, i.e. less than 300 mJ, to get phase pure CIGS thin films at room temperature. Particularly, even at room temperature, distinct crystalline CIGS phase was observed in the films. Crystallinity of the films improved with increasing substrate temperature as evidenced by the decrease of FWHM from 0.65 degto 0.54 deg. Slightly Cu-rich surface with Cu{sub 2-x}Se phase was confirmed to exist by Raman spectra, depending on substrate temperature. Improved electrical properties, i.e., carrier concentration of {proportional_to}10{sup 18} cm{sup -3} and resistivity of 10{sup -1}{omega} cm at higher substrate temperature for the optimal CIGS films are assumed to be induced by the potential contributions from highly crystallized thin films, existence of Cu{sub 2-x}Se phase and diffusion of Na from substrates to films. (author)

  1. Research on fabrication technology for thin film solar cells for practical use. Technological development for qualitative improvement (CuInSe2 based PV cell); Usumaku taiyo denchi seizo gijutsu no jitsuyoka kenkyu. Kohinshitsuka gijutsu (CuInSe2 taiyo denchi 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 CuInSe2 based PV cell in fiscal 1994. (1) On formation of high-quality CIGS thin films by bilayer method, Mo film was deposited on a glass substrate by sputtering, and CIGS film with different Ga/In ratios was next formed on the substrate by quaternary simultaneous deposition at different In and Ga deposition speeds. In addition, CdS film was deposited on the CIGS film, and ZnO and ITO films were finally deposited on it by sputtering to complete solar cell. This solar cell offered the maximum conversion efficiency among cells using CIGS film. (2) On formation of high-quality CIGS thin films by three-stage method, a certain correlation was found between substrate temperature and CIGS film composition by monitoring substrate temperature in film forming process. This phenomenon allowed rigorous control of CIS film compositions important for CIS thin film solar cells. (3) On low-cost process technology for thin film formation, Cu(In,Ga)S2 solid solution film was fabricated by expanded selenic process. 3 figs.

  2. Electrical properties from photoinduced charging on Cd-doped (100) surfaces of CuInSe{sub 2} epitaxial thin films

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Nicole, E-mail: nejhnsn2@illinois.edu; Rockett, Angus [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W Green St., Urbana, Illinois 61801 (United States); Aydogan, Pinar; Suzer, Sefik [Department of Chemistry, Bilkent University, 06800 Ankara (Turkey)

    2016-05-15

    The photoresponse of Cd-doped CuInSe{sub 2} (CIS) epitaxial thin films on GaAs(100) was studied using x-ray photoelectron spectroscopy under illumination from a 532 nm laser between sample temperatures of 28–260 °C. The initial, air-exposed surface shows little to no photoresponse in the photoelectron binding energies, the Auger electron kinetic energies or peak shapes. Heating between 50 and 130 °C in the analysis chamber results in enhanced n-type doping at the surface and an increased light-induced binding energy shift, the magnitude of which persists when the samples are cooled to room temperature from 130 °C but which disappears when cooling from 260 °C. Extra negative charge trapped on the Cu and Se atoms indicates deep trap states that dissociate after cooling from 260 °C. Analysis of the Cd modified Auger parameter under illumination gives experimental verification of electron charging on Cd atoms thought to be shallow donors in CIS. The electron charging under illumination disappears at 130 °C but occurs again when the sample is cooled to room temperature.

  3. Proposed suitable electron reflector layer materials for thin-film CuIn1-xGaxSe2 solar cells

    Science.gov (United States)

    Sharbati, Samaneh; Gharibshahian, Iman; Orouji, Ali A.

    2018-01-01

    This paper investigates the electrical properties of electron reflector layer to survey materials as an electron reflector (ER) for chalcopyrite CuInGaSe solar cells. The purpose is optimizing the conduction-band and valence-band offsets at ER layer/CIGS junction that can effectively reduce the electron recombination near the back contact. In this work, an initial device model based on an experimental solar cell is established, then the properties of a solar cell with electron reflector layer are physically analyzed. The electron reflector layer numerically applied to baseline model of thin-film CIGS cell fabricated by ZSW (efficiency = 20.3%). The improvement of efficiency is achievable by electron reflector layer materials with Eg > 1.3 eV and -0.3 AsS4 as well as CuIn1-xGaxSe (x > 0.5) are efficient electron reflector layer materials, so the potential improvement in efficiency obtained relative gain of 5%.

  4. Superconducting oxypnictide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Reisner, Andreas; Kidszun, Martin; Reich, Elke; Holzapfel, Bernhard; Schultz, Ludwig; Haindl, Silvia [IFW Dresden, Institute of Metallic Materials (Germany); Thersleff, Thomas [Uppsala University, Angstrom Laboratory (Sweden)

    2012-07-01

    We present an overview on the oxypnictide thin film preparation. So far, only LaAlO{sub 3} (001) single crystalline substrates provided a successful growth using pulsed laser deposition in combination with a post annealing process. Further experiments on the in-situ deposition will be reported. The structure of the films was investigated by X-ray diffractometry and transmission electron microscopy. Transport properties were measured with different applied fields to obtain a magnetic phase diagram for this new type of superconductor.

  5. Mechanics of Thin Films

    Science.gov (United States)

    1992-02-06

    and the second geometry was that of squat cylinders (diameter 6.4 mm, height 6.4 mm). These two geometries were tested in thermal shock tests, and a...milder [13]. More recently, Lau, Rahman and stressa nce ntrati, tha n films of lmalla rat ve spc Delale calculated the free edge singularity for stress...thickness of 3 mm); the second geometry was that As an example of the shielding effect of thin films, we of squat cylinders (diameter 6.4 mm, height 6.4

  6. Thin film processes

    CERN Document Server

    Vossen, John L

    1978-01-01

    Remarkable advances have been made in recent years in the science and technology of thin film processes for deposition and etching. It is the purpose of this book to bring together tutorial reviews of selected filmdeposition and etching processes from a process viewpoint. Emphasis is placed on the practical use of the processes to provide working guidelines for their implementation, a guide to the literature, and an overview of each process.

  7. Effect of selenization conditions on the growth and properties of Cu2ZnSn(S,Se)4 thin films

    OpenAIRE

    Ranjbar, Samaneh; Rajesh Menon, M.R.; Fernandes, P.A.; da Cunha, A.F.

    2015-01-01

    The opto-electronic properties of copper zinc tin sulfide can be tuned to achieve better cell efficiencies by controlled incorporation of selenium. In this paper we report the growth of Cu2ZnSn(S,Se)4 (CZTSSe) using a hybrid process involving the sequential evaporation of Zn and sputtering of the sulfide precursors of Cu and Sn, followed by a selenization step. Two approaches for selenization were followed, one using a tubular furnace and the other using a rapid thermal processor. The effects...

  8. Quarternair CuGaSeTe and CuGa0.5In 0.5Te2 Thin Films Fabrication Using Flash Evaporation

    Directory of Open Access Journals (Sweden)

    A Harsono Soepardjo

    2010-10-01

    Full Text Available Quarternair materials CuGaSeTe and CuGa0.5In 0.5Te2 are the basic materials to solar cell fabrication. These materials have high absorption coefficients around 103 - 105 cm-1 and band gap energy in the range of 1-5 eV. In this research, the films were made by flash evaporation method using quarternair powder materials of CuGaSeTe and CuGa0.5In 0.5Te2 to adhere in a glass substrate. After the films were obtained, the properties of these films will be characterized optically and electrically. The lattice parameter of the films and the crystalline film structure were obtained using X-Ray Diffraction (XRD spectroscopy. The XRD results show that the quarternair CuGaSeTe and CuGa0.5In 0.5Te2 films have a chalcopyrite structure. The absorption coefficient and the  band gap energy of the films were calculated using transmittance and reflectance patterns that measured using UV-VIS Difractometer. The films composition can be detected by using the Energy Dispersive Spectroscopy (EDS, while the films resistivity, mobility and the majority carrier of the films were obtained from Hall Effect experiments.

  9. Studies on dielectric properties, opto-electrical parameters and electronic polarizability of thermally evaporated amorphous Cd{sub 50}S{sub 50−x}Se{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hassanien, Ahmed Saeed, E-mail: a.s.hassanien@gmail.com [Engineering Mathematics and Physics Department, Faculty of Engineering (Shoubra), Benha University (Egypt); Physics Department, Faculty of Science and Humanities in Ad-Dawadmi, Shaqra University, 11911 (Saudi Arabia)

    2016-06-25

    The objective of this work is to study the influence of the addition of more Se on dielectric properties, opto-electrical parameters and electronic polarizability of amorphous chalcogenide Cd{sub 50}S{sub 50−x}Se{sub x} thin films (30 ≤ x ≤ 50 at%). Thin films of thickness 200 nm were synthesized by vacuum deposition at ≈8.2 × 10{sup −4} Pa. Both refractive index and extinction coefficient were used to obtain all the studied parameters. The high frequency dielectric constant, real and imaginary parts of dielectric constant were discussed. Drude theory was applied to investigate opto-electrical parameters, like optical carrier concentration, optical mobility and optical resistivity. Moreover, other parameters were investigated and studied, e.g. Drude parameters, volume and surface energy loss functions, dielectric loss factor, dielectric relaxation time, complex optical conductivity and electronic polarizability as well as optical electronegativity and third-order nonlinear optical susceptibility. Values of electronic polarizability and nonlinear optical susceptibility were found to be decreased while optical electronegativity increased as Se-content was increased. Increment of Se-content in amorphous Cd{sub 50}S{sub 50−x}Se{sub x} thin films has also led to minimize the energy losses when electromagnetic waves propagate through films as well as optical conductivity and the speed of light increased. The other studied properties and parameters of Cd{sub 50}S{sub 50−x}Se{sub x} films were found to be strongly dependent upon Se-content. - Highlights: • Thermally evaporated amorphous Cd{sub 50}S{sub 50−x}Se{sub x} (30 ≤ x ≤ 50) thin films were deposited. • Refractive index and absorption index were used to determine almost all properties. • Dielectric properties, Drude parameters and electronic polarizability were studied. • Addition of more Se to CdSSe matrix led to improve the opto-electrical properties. • New data were obtained and

  10. Handbook of thin film technology

    CERN Document Server

    Frey, Hartmut

    2015-01-01

    “Handbook of Thin Film Technology” covers all aspects of coatings preparation, characterization and applications. Different deposition techniques based on vacuum and plasma processes are presented. Methods of surface and thin film analysis including coating thickness, structural, optical, electrical, mechanical and magnetic properties of films are detailed described. The several applications of thin coatings and a special chapter focusing on nanoparticle-based films can be found in this handbook. A complete reference for students and professionals interested in the science and technology of thin films.

  11. The study of composition changes in thin film coatings of Ge-As-Se type under relativistic electron irradiation by means of electron Auger spectroscopy

    International Nuclear Information System (INIS)

    Kesler, L.G.; Dovgoshej, N.I.; Savchenko, N.D.

    1991-01-01

    Data on the influence of relativistic electrons on depth profile of Ge 33 As 12 Se 55 films were obtained for the first time. It was established that the most sufficient change of element composition of films in result of electron irradiation took place in the surface layer and on film-sublayer interface. It can be explained by increase of diffusion of impurities and free atoms

  12. Crystalline ordered states of CuIn1−xGaxSe2 (x = 0, 0.3, and 1.0) thin-films on different substrates investigated by Raman scattering spectroscopy

    International Nuclear Information System (INIS)

    Jeong, A.R.; Jo, W.; Song, M.; Yoon, S.

    2012-01-01

    Structural properties of Cu(In,Ga)Se 2 absorber layers have been examined for photovoltaic applications. Thin-films with three different chemical compositions, CuInSe 2 (CIS), Cu(In,Ga)Se 2 (CIGS) and CuGaSe 2 (CGS), were grown by co-evaporation on two kinds of substrates: Mo-coated soda-lime glass and bare soda-lime glass. Intriguing morphology and grain-growth behaviors were found in the surface of the films. X-ray diffraction of the films exhibited phase formation of the stoichiometric chalcopyrite phase of the materials while signs of secondary phases like Cu 2 Se and Cu–Se 2 were also observed. The optical transmittance of the films was measured to obtain their optical bandgaps, which were well matched with the bulk values of CIS, CIGS, and CGS, which are 1.1, 1.4, and 1.7 eV, respectively. Using Raman scattering spectroscopy, the A 1 mode was observed to shift from 177 cm −1 for CIS to 189 cm −1 for CGS as the Ga content increased. The films on Mo substrates are likely to have secondary phases, which is not the case for soda-lime glass. An indication of the formation of the CuAu structure is obtained from the CIS thin-films. - Highlights: ► We report structural and optical properties of CIGS films on different substrates. ► Various optical tools were used to characterize the CIGS films. ► Crystalline ordered states were examined by A1 mode of Raman spectra.

  13. The effect of Na on the electronic properties of Cu(In,Ga)Se{sub 2} thin films: A local-probe study

    Energy Technology Data Exchange (ETDEWEB)

    Azulay, D. [Racah Institute of Physics, The Hebrew University, Jerusalem (Israel); Azrieli, College of Engineering, Jerusalem (Israel); Abou-Ras, D. [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Popov, I. [The Hebrew University Center for Nanoscience and Nanotechnology, Jerusalem (Israel); Balberg, I.; Millo, O. [Racah Institute of Physics, The Hebrew University, Jerusalem (Israel); The Hebrew University Center for Nanoscience and Nanotechnology, Jerusalem (Israel)

    2016-06-15

    We investigated the effect of Na incorporation on the electronic properties of polycrystalline CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films using scanning tunneling microscopy and spectroscopy. The tunneling spectra indicate a reduced in-gap density of states at grain boundaries and reveal a downward band-bending in Na-rich grain boundaries with respect to the adjacent grains, in agreement with our conductive atomic force microscopy data. It thus appears that Na passivates deep-level defects at grain boundaries and induces a downward band-bending there. Moreover, we provide evidence that Na passivates mainly Cu vacancy related defects. We suggest that the grain-boundary passivation, which reduces the recombination rate of photogenerated carriers, is at least of major importance in the well known Na-induced improvement in the efficiency of the corresponding solar cells. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Spin-orbit torque in a thin film of the topological insulator Bi2Se3: Crossover from the ballistic to diffusive regime

    Science.gov (United States)

    Ren, Y. J.; Deng, W. Y.; Geng, H.; Shen, R.; Shao, L. B.; Sheng, L.; Xing, D. Y.

    2017-12-01

    The spin-orbit torque provides an efficient method for switching the direction of a magnetization by using an electric field. Owing to the spin-orbit coupling, when an electric field is applied, a nonequilibrium spin density is generated, which exerts a torque on the local magnetization. Here, we investigate the spin-orbit torque in a thin film of topological insulator \\text{Bi}2\\text{Se}3 based upon a Boltzmann equation, with proper boundary conditions, which is applicable from the ballistic regime to the diffusive regime. It is shown that due to the spin-momentum interlocking of the electron surface states, the magnitude of the field-like torque is simply in linear proportion to the longitudinal electrical current. For a fixed electric field, the spin-orbit torque is proportional to the sample length in the ballistic limit, and saturates to a constant in the diffusive limit. The dependence of the torque on the magnetization direction and exchange coupling strength is also studied. Our theory may offer useful guidance for experimental investigations of the spin-orbit torque in finite-size systems.

  15. Individual identification of free hole and electron dynamics in CuIn{sub 1−x}Ga{sub x}Se{sub 2} thin films by simultaneous monitoring of two optical transitions

    Energy Technology Data Exchange (ETDEWEB)

    Okano, Makoto [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Hagiya, Hideki; Sakurai, Takeaki; Akimoto, Katsuhiro [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Shibata, Hajime; Niki, Shigeru [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Kanemitsu, Yoshihiko, E-mail: kanemitu@scl.kyoto-u.ac.jp [Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011 (Japan); Japan Science and Technology Agency, CREST, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    2015-05-04

    The photocarrier dynamics of CuIn{sub 1−x}Ga{sub x}Se{sub 2} (CIGS) thin films were studied using white-light transient absorption (TA) measurements, as an understanding of this behavior is essential for improving the performance of solar cells composed of CIGS thin films. A characteristic double-peak structure due to the splitting of the valence bands in the CIGS was observed in the TA spectra under near-band-gap resonant excitation. From a comparison of the TA decay dynamics monitored at these two peaks, it was found that the slow-decay components of the electron and hole relaxation are on the nanosecond timescale. This finding is clear evidence of the long lifetimes of free photocarriers in polycrystalline CIGS thin films.

  16. First principles calculations of point defect diffusion in CdS buffer layers: Implications for Cu(In,Ga)(Se,S){sub 2} and Cu{sub 2}ZnSn(Se,S){sub 4}-based thin-film photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Varley, J. B.; Lordi, V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); He, X.; Rockett, A. [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2016-01-14

    We investigate point defects in CdS buffer layers that may arise from intermixing with Cu(In,Ga)Se{sub 2} (CIGSe) or Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) absorber layers in thin-film photovoltaics (PV). Using hybrid functional calculations, we characterize the migration barriers of Cu, In, Ga, Se, Sn, Zn, Na, and K impurities and assess the activation energies necessary for their diffusion into the bulk of the buffer. We find that Cu, In, and Ga are the most mobile defects in CIGS-derived impurities, with diffusion expected to proceed into the buffer via interstitial-hopping and cadmium vacancy-assisted mechanisms at temperatures ∼400 °C. Cu is predicted to strongly favor migration paths within the basal plane of the wurtzite CdS lattice, which may facilitate defect clustering and ultimately the formation of Cu-rich interfacial phases as observed by energy dispersive x-ray spectroscopic elemental maps in real PV devices. Se, Zn, and Sn defects are found to exhibit much larger activation energies and are not expected to diffuse within the CdS bulk at temperatures compatible with typical PV processing temperatures. Lastly, we find that Na interstitials are expected to exhibit slightly lower activation energies than K interstitials despite having a larger migration barrier. Still, we find both alkali species are expected to diffuse via an interstitially mediated mechanism at slightly higher temperatures than enable In, Ga, and Cu diffusion in the bulk. Our results indicate that processing temperatures in excess of ∼400 °C will lead to more interfacial intermixing with CdS buffer layers in CIGSe devices, and less so for CZTSSe absorbers where only Cu is expected to significantly diffuse into the buffer.

  17. The influence of different locations of sputter guns on the morphological and structural properties of Cu–In–Ga precursors and Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.; Zhu, J., E-mail: jiezhu@ustb.edu.cn; He, Y.X.

    2014-01-01

    The influence of two different locations of sputter guns on the morphological and structural properties of Cu–In–Ga precursors and Cu(In,Ga)Se{sub 2} (CIGS) thin films was investigated. All the precursors contained cauliflower-like nodules, whereas smaller subnodules were observed on the background. All the precursors revealed apparent three-layered structures, and voids were observed at the CIGS/SLG interface of Sets 1 and 2 films rather than Set 3 film. EDS results indicated that all CIGS thin films were Cu-deficient. Based on the grazing incidence X-ray diffraction (GIXRD) patterns, as-selenized films showed peaks corresponding to the chalcopyrite-type CIGS structure. Depth-resolved Raman spectra showed the formation of a dominant CIGS phase inside the films for all the as-selenized samples investigated, and of an ordered vacancy compound (OVC) phase like Cu(In,Ga){sub 3}Se{sub 5} or Cu(In,Ga){sub 2}Se{sub 3.5} at the surface and/or CIGS/SLG interface region of Sets 2 and 3 films. No evidence was obtained on the presence of an OVC phase in Set 1 CIGS film, which may be speculated that long-time annealing is contributed to suppress the growth of OVC phases. The results of the present work suggest that the metallic precursors deposited with the upright-location sputter gun might be more appropriate to prepare CIGS thin films than those sputtered with the titled-location gun.

  18. Effect of bath temperature on the properties of CuIn{sub x}Ga{sub 1-x} Se{sub 2} thin films grown by the electrodeposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Cao Jie; Qu Shengchun; Liu Kong; Wang Zhanguo, E-mail: qsc@semi.ac.c [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2010-08-15

    Electrodeposition is a promising and low cost method to synthesize CuIn{sub x} Ga{sub 1-x} Se{sub 2} (CIGS)thin films as an absorber layer for solar cells. The effect of bath temperature on the properties of CIGS thin films was investigated in this paper. CIGS films of 1 {mu}m thickness were electrodeposited potentiostatically from aqueous solution, containing trisodium citrate as a complexing agent, on Mo/glass substrate under a voltage of -0.75 V, and bath temperatures were varied from 20 to 60{sup 0}C. The effects of bath temperature on the properties of CIGS thin films were characterized by X-ray diffraction (XRD) and scanning electron microscopy. XRD revealed the presence of the CuIni{sub 0.7}Ga{sub 0.3} Se{sub 2} phase, the optimal phase for application in solar cells. The grain dimensions and crystallizability increase along with the increase of the bath temperature, and the films become stacked and homogeneous. There were few changes in surface morphology and the composition of the films. (semiconductor materials)

  19. Thin films for precision optics

    International Nuclear Information System (INIS)

    Araujo, J.F.; Maurici, N.; Castro, J.C. de

    1983-01-01

    The technology of producing dielectric and/or metallic thin films for high precision optical components is discussed. Computer programs were developed in order to calculate and register, graphically, reflectance and transmittance spectra of multi-layer films. The technology of vacuum evaporation of several materials was implemented in our thin-films laboratory; various films for optics were then developed. The possibility of first calculate film characteristics and then produce the film is of great advantage since it reduces the time required to produce a new type of film and also reduces the cost of the project. (C.L.B.) [pt

  20. Influence of the grid and cell design on the power output of thin film Cu(InGa)Se2 cells

    NARCIS (Netherlands)

    Deelen, J. van; Frijters, C.; Suijlen, M.; Barink, M.

    2015-01-01

    The effect of the front contact characteristics on the working of monolithically integrated thin film solar panels and effective ways of improving the front contact are discussed. Efficiencies were calculated for various cell lengths and scribing areas in between cells (interconnection dead zone

  1. Comparative study about Al-doped zinc oxide thin films deposited by Pulsed Electron Deposition and Radio Frequency Magnetron Sputtering as Transparent Conductive Oxide for Cu(In,Ga)Se{sub 2}-based solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Pattini, F., E-mail: pattini@imem.cnr.it [IMEM-CNR, Institute of Materials for Electronics and Magnetism, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Annoni, F.; Bissoli, F.; Bronzoni, M. [IMEM-CNR, Institute of Materials for Electronics and Magnetism, Parco Area delle Scienze 37/A, 43124 Parma (Italy); Garcia, J.P. [Delft University of Technology, Faculty of Applied Sciences, Delft Product and Process Design Institute, Julianalaan 67, 2628 BC Delft (Netherlands); Gilioli, E.; Rampino, S. [IMEM-CNR, Institute of Materials for Electronics and Magnetism, Parco Area delle Scienze 37/A, 43124 Parma (Italy)

    2015-05-01

    In this study, a comparison between Al-doped ZnO (AZO) as Transparent Conductive Oxide for Cu(In,Ga)Se{sub 2}-based solar cells grown by Pulsed Electron Deposition (PED) and Radio Frequency Magnetron Sputtering (RFMS) was performed. PED yielded polycrystalline [002] mono-oriented thin films with low electrical resistivity and high optical transparency with heater temperatures ranging from room temperature (RT) to 250 °C. The electrical resistivity of these films can be tuned by varying the heater temperature, reaching a minimum value of 3.5 × 10{sup −4} Ωcm at 150 °C and an average transmittance over 90% in the visible range. An AZO film grown at RT was deposited by PED on an actual Cu(In,Ga)Se{sub 2}-based solar cell, resulting to an efficiency value of 15.2% on the best device. This result clearly shows that PED is a suitable technique for growing ZnO-based thin films for devices/applications where low deposition temperature is required. On the other hand, an optimized AZO thin film front contact for thin film solar cells was studied and fabricated via RFMS. The parameters of this technique were tweaked to obtain highly conductive and transparent AZO thin films. The lowest resistivity value of 3.7 × 10{sup −4} Ωcm and an average transmittance of 86% in the 400-1100 nm wavelength range was obtained with a heater temperature of 250 °C. A thick sputtered AZO film was deposited at RT onto an identical cell used for PED-grown AZO, reaching the highest conversion efficiency value of 14.7%. In both cases, neither antireflection coatings nor pure ZnO layer was used. - Highlights: • Pulsed Electron Deposition (PED) lets high quality films grow at low temperature. • Al:ZnO (AZO) thin films grown by PED present high optical and electrical quality. • AZO electrical resistivity can be tuned from 10{sup −4} to 10{sup −2} Ωcm in proper condition. • Cu(In,Ga)Se{sub 2}-based simplified solar cells achieved efficiency of 15.2% for PED-grown AZO.

  2. The effect of Se/Te ratio on transient absorption behavior and nonlinear absorption properties of CuIn0.7Ga0.3(Se1-xTex)2 (0 ≤ x ≤ 1) amorphous semiconductor thin films

    Science.gov (United States)

    Karatay, Ahmet; Küçüköz, Betül; Çankaya, Güven; Ates, Aytunc; Elmali, Ayhan

    2017-11-01

    The characterization of the CuInSe2 (CIS), CuInGaSe (CIGS) and CuGaSe2 (CGS) based semiconductor thin films are very important role for solar cell and various nonlinear optical applications. In this paper, the amorphous CuIn0.7Ga0.3(Se1-xTex)2 semiconductor thin films (0 ≤ x ≤ 1) were prepared with 60 nm thicknesses by using vacuum evaporation technique. The nonlinear absorption properties and ultrafast transient characteristics were investigated by using open aperture Z-scan and ultrafast pump-probe techniques. The energy bandgap values were calculated by using linear absorption spectra. The bandgap values are found to be varying from 0.67 eV to 1.25 eV for CuIn0.7Ga0.3Te2, CuIn0.7Ga0.3Se1.6Te0.4, CuIn0.7Ga0.3Se0.4Te1.6 and CuIn0.7Ga0.3Se2 thin films. The energy bandgap values decrease with increasing telluride (Te) doping ratio in mixed CuIn0.7Ga0.3(Se1-xTex)2 films. This affects nonlinear characteristics and ultrafast dynamics of amorphous thin films. Ultrafast pump-probe experiments indicated that decreasing of bandgap values with increasing the Te amount switches from the excited state absorption signals to ultrafast bleaching signals. Open aperture Z-scan experiments show that nonlinear absorption properties enhance with decreasing bandgaps values for 65 ps pulse duration at 1064 nm. Highest nonlinear absorption coefficient was found for CuIn0.7Ga0.3Te2 thin film due to having the smallest energy bandgap.

  3. Microstructure of Thin Films

    Science.gov (United States)

    1990-02-07

    Proceedings, Thin film Technologies II, 652, 256-263, (1986) B. Schmitt, J.P. Borgogno, G. Albrand and E. Pelletier, "In situ and air index measurements...34 SPIE Proceedings, "Optical Components and Systems", 805, 128 (1987) 11 B. Schmitt, J.P. Borgogno, G. Albrand and E. Pelletier. "In situ and air index...aT , m..a, lot,, o ,,f,02,d I4 k -1-1..... autocovariance lengths, less than 0.5 um, indicate that , 514n, ob0 o p’,Ofclllc....,,o,,oy0,1- agua sblrt

  4. Molybdenum thin film deposited by in-line DC magnetron sputtering as a back contact for Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li Zhaohui; Cho, Eou-Sik [Department of Electronics Engineering, Kyungwon University, San 65, Bokjung-dong, Soojung-gu, Seongnam city, Kyunggi-do, 461-701 (Korea, Republic of); Kwon, Sang Jik, E-mail: sjkwon@kyungwon.ac.kr [Department of Electronics Engineering, Kyungwon University, San 65, Bokjung-dong, Soojung-gu, Seongnam city, Kyunggi-do, 461-701 (Korea, Republic of)

    2011-09-01

    In this paper, we reported the effect of the power and the working pressure on the molybdenum (Mo) films deposited using an in-line direct current (DC) magnetron sputtering system. The electrical and the structural properties of Mo film were improved by increasing DC power from 1 to 3 kW. On the other side, the resistivity of the Mo films became higher with the increasing working pressure. However, the adhesion property was improved when the working pressure was higher. In this work, in order to obtain an optimal Mo film as a back metal contact of Cu(In,Ga)Se{sub 2} (CIGS) solar cells, a bilayer Mo film was formed through the different film structures depending on the working pressure. The first layer was formed at a high pressure of 12 mTorr for a better adhesion and the second layer was formed at a low pressure of 3 mTorr for a lower resistivity.

  5. Improvement in the electronic quality of pulsed laser deposited CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films via post-deposition elemental sulfur annealing process

    Energy Technology Data Exchange (ETDEWEB)

    Beres, M., E-mail: matthewcberes@gmail.com [University of California, Department of Mechanical Engineering, 6141 Etcheverry Hall, Berkeley, CA 94720 (United States); Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Yu, K.M., E-mail: kinmanyu@cityu.edu.hk [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); City University of Hong Kong, Department of Physics and Materials Science, 83 Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Syzdek, J., E-mail: jego.mejl@gmail.com [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Bio-Logic USA, 9050 Executive Park Dr NW, Knoxville, TN 37923 (United States); Mao, S.S., E-mail: ssmao@me.berkeley.edu [University of California, Department of Mechanical Engineering, 6141 Etcheverry Hall, Berkeley, CA 94720 (United States); Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 (United States)

    2016-06-01

    We synthesized CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films on soda lime glass substrates using pulsed laser deposition and post-annealing under different conditions. Increasing substrate temperature during deposition and vacuum annealing after deposition both increased grain size but had negligible effect on the electronic properties of the films. As-deposited films demonstrated P-type conductivities with high carrier concentrations and low Hall mobilities, but annealing in elemental sulfur environment significantly improved the electronic properties of the films. We found that the incorporation of even small quantities of sulfur into the films reduced carrier concentrations by over three orders of magnitude and increased Hall mobilities by an order of magnitude. This resulted in films with resistivity ~ 5 Ω·cm suitable for photovoltaic applications. - Highlights: • CIGSe thin films were deposited by pulsed laser deposition. • Laser deposition parameters and annealing parameters were investigated. • As-deposited films demonstrated high hole concentrations and low Hall mobilities. • Elemental sulfur annealing significantly enhanced the electronic quality of films.

  6. Host thin films incorporating nanoparticles

    Science.gov (United States)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  7. Formation and electronic properties of In2S3/Cu(In,Ga)Se2 junctions and related thin film solar cells

    International Nuclear Information System (INIS)

    Pistor, Paul

    2009-01-01

    In this work, thermally evaporated In 2 S 3 thin films have been used as buffer layers in Cu(In,Ga)Se 2 solar cells. The state of the art Cu(In,Ga)Se 2 solar cell with CdS buffer layer was the starting point for this work and the role of the buffer layer as well as alternative buffer layer concepts were introduced in the beginning, together with some theoretical considerations needed for the physical interpretation of solar cell parameters. High quality, crystalline In 2+x S 3 was successfully synthesised and used as a reference material for the structural characterisation of In 2 S 3 . Three modifications with tetragonal, cubic and trigonal symmetry were identified and characterised with X-ray diffraction (XRD) measurements in the temperature range from 31 C to 1040 C. A refinement by the Rietveld method was performed, extending the existing literature data on the structure of In 2 S 3 . Resulting In 2 S 3 thin films were stoichiometric and homogeneous with an indirect optical bandgap of (1.99±0.5) eV. The utilisation of crystalline, single phase source material and the development of appropriate buffer processing led to high efficiency solar cells. A key process for optimal device performance was post deposition annealing of the completed solar cells for 35 min. to 55 min. at a temperature of 200 C. Annealing was found to improve mainly the fill factor and open circuit voltage of devices with an In 2 S 3 buffer, independent of the atmosphere in which the annealing was carried out (e.g. in air or inert gas). The controlled and reproducible enhancement of the device performance during annealing allowed coherent analysis of the changes in the photo-generated charge carrier collection and the dominant recombination mechanism of the solar cell devices. Losses in the spectral response upon annealing observed at long wavelengths (700-1200 nm) were attributed to a reduction of the space charge region width at the In 2 S 3 /Cu(In,Ga)Se 2 junction. Prior to annealing, it

  8. Recombination luminescence and trap levels in undoped and Al-doped ZnO thin films on quartz and GaSe (0 0 0 1) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Evtodiev, I. [Moldova State University, 60 A. Mateevici Str., Chisinau, MD 2009, Republic of Moldova (Moldova, Republic of); Caraman, I. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania); Leontie, L., E-mail: lleontie@uaic.ro [Alexandru Ioan Cuza University of Iasi, Bd. Carol I, Nr. 11, RO 700506 Iasi (Romania); Rusu, D.-I. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania); Dafinei, A. [Faculty of Physics, University of Bucharest, Platforma Magurele, Str. Fizicienilor nr. 1, CP Mg - 11, Bucharest-Magurele, RO 76900 (Romania); Nedeff, V.; Lazar, G. [Vasile Alecsandri University of Bacau, 157 Calea Marasesti, RO 600115 Bacau (Romania)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer ZnO films on GaSe create electron trapping states and PL recombination levels. Black-Right-Pointing-Pointer Zn and Al diffusion in GaSe produces low-energy widening of its PL emission. Black-Right-Pointing-Pointer ZnO:Al films on GaSe lamellas are suitable for gas-discharge lamp applications. -- Abstract: Photoluminescence spectra of ZnO and ZnO:Al (1.00, 2.00 and 5.00 at.%) films on GaSe (0 0 0 1) lamellas and amorphous quartz substrates, obtained by annealing, at 700 K, of undoped and Al-doped metal films, are investigated. For all samples, the nonequilibrium charge carriers recombine by radiative band-to-band transitions with energy of 3.27 eV, via recombination levels created by the monoionized oxygen atoms, forming the impurity band laying in the region 2.00 - 2.70 eV. Al doping induces an additional recombination level at 1.13 eV above the top of the valence band of ZnO films on GaSe substrates. As a result of thermal diffusion of Zn and Al into the GaSe interface layer from ZnO:Al/GaSe heterojunction, electron trap levels located at 0.22 eV and 0.26 eV below the conduction band edge of GaSe, as well as a deep recombination level, responsible for the luminescent emission in the region 1.10 - 1.40 eV, are created.

  9. Influence of composition on optical and dispersion parameters of thermally evaporated non-crystalline Cd{sub 50}S{sub 50−x}Se{sub x} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hassanien, A.S., E-mail: a.s.hassanien@gmail.com [Engineering Mathematics and Physics Dept., Faculty of Engineering (Shoubra), Benha University (Egypt); Physics Department, Faculty of Science and Humanities in Ad-Dawadmi, Shaqra University, 11911 (Saudi Arabia); Akl, Alaa A. [Physics Department, Faculty of Science and Humanities in Ad-Dawadmi, Shaqra University, 11911 (Saudi Arabia)

    2015-11-05

    Non-crystalline thin films of chalcogenide Cd{sub 50}S{sub 50−x}Se{sub x} system (30 ≤ x ≤ 50) were obtained by thermal evaporation technique onto a pre-cleaned glass substrate at a vacuum of 8.2 × 10{sup −4} Pa. The deposition rate and film thickness were kept constant at about 8 nm/s and 200 nm, respectively. Amorphous/crystalline nature and chemical composition of films have been checked using X-ray diffraction and energy dispersive X-ray spectroscopy (EDX). Optical properties of thin films were investigated and studied using the corrected transmittance, T(λ) and corrected reflectance, R(λ) measurements. Obtained data reveal that, the indirect optical energy gap (E{sub g}) was decreased from 2.21 to 1.57 eV. On the contrary, Urbach energy (band tail width), E{sub U} was found to be increased from 0.29 to 0.45 eV. This behavior is believed to be associated with the increase of Se-content instead of S-content in the thin films of Cd{sub 50}S{sub 50−x}Se{sub x} system. Chemical bond approach model, CBA was used to analyze the obtained values of E{sub g} and E{sub U}. Optical density, skin depth, extinction coefficient, refractive index and optical conductivity of chalcogenide CdSSe thin films were discussed as functions of Se-content. Using Wemple-DiDomenico single oscillator model, the refractive index dispersion and energy parameters and their dependence on Se content were studied. - Highlights: • Amorphous thin films of thickness 200 nm of Cd{sub 50}S{sub 50−x}Se{sub x} (30 ≤ x ≤ 50) have prepared. • Optical properties, indirect optical energy gap and band tail width were studied. • Chemical bond approach, CBA was used to analyze the obtained values of E{sub g} and E{sub U}. • New data of dispersion refractive index parameters were investigated and discussed.

  10. Thickness and growth-condition dependence of in-situ mobility and carrier density of epitaxial thin-film Bi2Se3

    International Nuclear Information System (INIS)

    Hellerstedt, Jack; Fuhrer, Michael S.; Edmonds, Mark T.; Zheng, C. X.; Chen, J. H.; Cullen, William G.

    2014-01-01

    Bismuth selenide Bi 2 Se 3 was grown by molecular beam epitaxy, while carrier density and mobility were measured directly in situ as a function of film thickness. Carrier density shows high interface n-doping (1.5 × 10 13  cm −2 ) at the onset of film conduction and bulk dopant density of ∼5 × 10 11  cm −2 per quintuple-layer unit, roughly independent of growth temperature profile. Mobility depends more strongly on the growth temperature and is related to the crystalline quality of the samples quantified by ex-situ atomic force microscopy measurements. These results indicate that Bi 2 Se 3 as prepared by widely employed parameters is n-doped before exposure to atmosphere, the doping is largely interfacial in origin, and dopants are not the limiting disorder in present Bi 2 Se 3 films.

  11. Polymer Thin Film Stabilization.

    Science.gov (United States)

    Costa, A. C.; Oslanec, R.; Composto, R. J.; Vlcek, P.

    1998-03-01

    We study the dewetting dynamics of thin polystyrene (PS) films deposited on silicon oxide surfaces using optical (OM) and atomic force (AFM) microscopes. Quantitative analysis of the hole diameter as a function of annealing time at 175^oC shows that blending poly(styrene-block-methyl-methacrylate) (PS-b-PMMA) with PS acts to dramatically slow down the dewetting rate and even stops holes growth before they impinge. AFM studies show that the hole floor is smooth for a pure PS film but contains residual polymer for the blend. At 5% vol., a PS-b-PMMA with high molar mass and low PMMA is a more effective stabilizing agent than a low molar mass/high PMMA additive. The optimum copolymer concentration is 3% vol. beyond which film stability doesn't improve. Although dewetting is slowed down relative to pure PS, PS/PS-b-PMMA bilayers dewet at a faster rate than blends having the same overall additive concentration.

  12. Thin films: Past, present, future

    Energy Technology Data Exchange (ETDEWEB)

    Zweibel, K

    1995-04-01

    This report describes the characteristics of the thin film photovoltaic modules necessary for an acceptable rate of return for rural areas and underdeveloped countries. The topics of the paper include a development of goals of cost and performance for an acceptable PV system, a review of current technologies for meeting these goals, issues and opportunities in thin film technologies.

  13. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with

  14. Thin-film solar cells

    International Nuclear Information System (INIS)

    Aberle, Armin G.

    2009-01-01

    The rapid progress that is being made with inorganic thin-film photovoltaic (PV) technologies, both in the laboratory and in industry, is reviewed. While amorphous silicon based PV modules have been around for more than 20 years, recent industrial developments include the first polycrystalline silicon thin-film solar cells on glass and the first tandem solar cells based on stacks of amorphous and microcrystalline silicon films ('micromorph cells'). Significant thin-film PV production levels are also being set up for cadmium telluride and copper indium diselenide.

  15. Optical properties and photoinduced phenomena in glasses and thin films of system As2Se3-As2Te3-SnTe

    Czech Academy of Sciences Publication Activity Database

    Parchanski, V.; Frumarová, Božena; Frumar, M.; Hrdlička, M.; Vlček, Milan

    2012-01-01

    Roč. 14, 1-2 (2012), 150-156 ISSN 1454-4164 R&D Projects: GA ČR GA203/09/0827 Institutional research plan: CEZ:AV0Z40500505 Keywords : chalcogenides * thin films * optical properties Subject RIV: CA - Inorganic Chemistry Impact factor: 0.516, year: 2012 http://joam.inoe.ro/index.php?option=magazine&op=view&idu=2997&catid=69

  16. Synthesis of CuInSe2 thin films from electrodeposited Cu11In9 precursors by two-step annealing

    Directory of Open Access Journals (Sweden)

    TSUNG-WEI CHANG

    2014-02-01

    Full Text Available In this study, copper indium selenide (CIS films were synthesized from electrodeposited Cu-In-Se precursors by two-step annealing. The agglomeration phenomenon of the electrodeposited In layer usually occurred on the Cu surface. A thermal process was adopted to turn Cu-In precursors into uniform Cu11In9 binary compounds. After deposition of the Se layer, annealing was employed to form chalcopyrite CIS. However, synthesis of CIS from Cu11In9 requires sufficient thermal energy. Annealing temperature and time were investigated to grow high quality CIS film. Various electrodeposition conditions were investigated to achieve the proper atomic ratio of CIS. The properties of the CIS films were characterized by scanning electron microscopy (SEM, X-ray Diffraction (XRD, and Raman spectra.

  17. Influence of annealing temperature on properties of Cu(In,Ga)(Se,S){sub 2} thin films prepared by co-sputtering from quaternary alloy and In{sub 2}S{sub 3} targets

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.C., E-mail: ielinyc@cc.ncue.edu.t [Department of Mechatronics Engineering, National Changhua University of Education, No. 2, Shida Road, Changhua 50074, Taiwan (China); Yen, W.T.; Chen, Y.L.; Wang, L.Q. [Department of Mechatronics Engineering, National Changhua University of Education, No. 2, Shida Road, Changhua 50074, Taiwan (China); Jih, F.W. [Chung-Shan Institute of Science and Technology, No. 15, Shi Qi Zi, Gaoping village, Longtan Township, Taoyuan County, Taiwan (China)

    2011-02-15

    Pentanary Cu(In,Ga)(Se,S){sub 2} (CIGSS) thin films were deposited on soda-lime glass substrate by co-sputtering quaternary alloy, and In{sub 2}S{sub 3} targets. In this study, we investigated the influence of post-annealing temperature on structural, compositional, electrical, and optical properties of CIGSS films. Our experimental results show that the CIGS quaternary target had chalcopyrite characteristics. All CIGSS films annealed above 733 K exhibited a polycrystalline tetragonal chalcopyrite structure, with (1 1 2) preferred orientation. The carrier concentration and resistivity of the resultant CIGSS layer annealed above 763 K was 4.86x10{sup 16} cm{sup -3} and 32 {Omega} cm, respectively, and the optical band-gap of the CIGSS absorber layer was 1.18 eV. Raman spectral analysis demonstrated the existence of many different phases, including CuInSe{sub 2}, CuGaSe{sub 2}, and CuInS{sub 2}. This may be because the vibration frequencies of In-Se, In-S bonds are similar to the Ga-Se and Ga-S bonds, causing their absorption bands overlap. -- Research Highlights: {yields} We report a chalcopyrite Cu(In,Ga)(Se,S){sub 2} (CIGSS) thin films on soda lime glass substrate by co-sputtering quaternary single-phase chalcopyrite CIGS alloy, and In{sub 2}S{sub 3} targets. {yields} By incorporating sulfur into partly selenized CIGS films, researchers fabricated a chalcopyrite CIGSS layer with double-graded band-gap structure. {yields} The CIGS quaternary target and Raman spectra were analyzed for investigating the CIGSS structure and quality.

  18. Preparation of CuGaSe2 absorber layers for thin film solar cells by annealing of efficiently electrodeposited Cu-Ga precursor layers from ionic liquids

    International Nuclear Information System (INIS)

    Steichen, M.; Larsen, J.; Guetay, L.; Siebentritt, S.; Dale, P.J.

    2011-01-01

    CuGaSe 2 absorber layers were prepared on molybdenum substrates by electrochemical codeposition of copper and gallium and subsequential annealing in selenium vapour. The electrodeposition was made from a deep eutectic based ionic liquid consisting of choline chloride/urea (Reline) with a plating efficiency of over 85%. The precursor film composition is controlled by the ratio of the copper to gallium fluxes under hydrodynamic conditions and by the applied deposition potential. X-ray diffraction reveals CuGa 2 alloying during the electrodeposition and CuGaSe 2 formation after annealing. Photoluminescence (PL) and photocurrent spectroscopy revealed the good opto-electronic properties of the CuGaSe 2 absorber films. The absorber layers have been converted to full devices with the best device achieving 4.0 % solar conversion efficiency.

  19. Effect of substrate temperature on the optical, structural and morphological properties of In{sub 2}Se{sub 3} thin films grown by a two-step process

    Energy Technology Data Exchange (ETDEWEB)

    Clavijo, J; Gordillo, G [Departamento de Fisica, Universidad Nacional de Colombia, Bogota (Colombia); Romero, E, E-mail: jiclavijop@unal.edu.c, E-mail: erromerom@unal.edu.c, E-mail: ggordillog@unal.edu.c

    2009-05-01

    Polycrystalline gamma - In{sub 2}Se{sub 3} thin films with adequate properties to use them as buffer layer in solar cells, were grown on corning glass substrates using a novel procedure which includes the formation of the alpha- In{sub 2}Se{sub 3} phase in a first step followed by thermal annealing in Se ambient to activate the formation of the gamma- In{sub 2}Se{sub 3} phase. X-ray diffraction (XRD) measurements revealed that the substrate temperature strongly affects the phase in which the indium selenide films grow; at substrate temperatures of around 300{sup 0}C the indium selenide grow in the alpha-In{sub 2}Se{sub 3} phase, whereas the samples deposited at temperatures between 300 and 550{sup 0}C grow with a mixture of the alpha-In{sub 2}Se{sub 3} and gamma-In{sub 2}Se{sub 3} phases. The alpha-In{sub 2}Se{sub 3} samples change into the gamma-In{sub 2}Se{sub 3} phase when subjected to heat treatment around 550{sup 0}C in Se ambient. Spectrophotometric measurements also revealed that the phase in which the indium selenide films grow, significantly affects the optical gap Eg. Eg values of 1.47 eV and 2.11 eV were determined for the alpha-In{sub 2}Se{sub 3} and gamma-In{sub 2}Se{sub 3} films respectively, indicating that this gamma-In{sub 2}Se{sub 3} compound has better properties to perform as buffer layer in thin film solar cells. The effect of substrate temperature on the structural, optical and morphological properties was investigated using XRD, spectral transmittance and atomic force microscope (AFM) measurements. Theoretical simulation of the XRD pattern carried out with the help of the PowderCell package, allowed us to identify the phases associated to the X-Ray reflections, with a good degree of confidence.

  20. Development of a new thin film technology for PV systems: Open-system CCSVT process for production of ZnSe/CuGaSe{sub 2} hetero diodes. Final report; Entwicklung einer neuen Duennschichttechnologie fuer die Photovoltaik: CCSVT-Verfahren im offenen System zur Herstellung von ZnSe/CuGaSe{sub 2}-Heterodioden. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Lux-Steiner, M.C.; Jaeger-Waldau, A.

    2000-07-01

    A new technology for fast, large-surface deposition of high-quality semiconducting thin films for PV systems. The new technology, CSVT (close-space vapour transport), is based on a combination of VPE (vapour phase epitaxy) in open systems and CVT (chemical vapour phase transport) in closed systems. The two-source CVD experiments with two different transport gases, i.e. Cu{sub 2}Se with iodine and Ga{sub 2}Se{sub 3} with HCl, enabled controlled variation of the Cu:Ga ratio in the gaseous phase. The solar cells produced had efficiencies of more than 4%. The best solar cell produced had an efficiency of 4.8% and an open terminal voltage of 863 mV. [German] Ziel des Vorhabens war die Entwicklung einer neuen Technologie zur schnellen, grossflaechigen Abscheidung von qualitativ hochstehenden, halbleitenden Duennschichten fuer die Photovoltaik. Das Konzept des neuen Abscheideverfahrens, CSVT (close-space vapour transport) im offenen System, basiert auf einer Kombination der etablierten Methoden VPE (vapour phase epitaxy) im offenen und CVT (chemical vapour phase transport) im geschlossenen System. Die 2-Quellen-CVD-Experimente mit den zwei unterschiedlichen Transportgasen (Cu{sub 2}Se mit Iod; Ga{sub 2}Se{sub 3} mit HCl) ermoeglichten die kontrollierte Variation des Cu:Ga=Verhaeltnisses in der Gasphase. Bisher konnten so Solarzellen mit Wirkungsgraden ueber 4% hergestellt werden, wobei bei der bisher besten Solarzelle ein Wirkungsgrad von {eta}=4.8% und eine offene Klemmenspannung von V{sub oc}=863 mV erreicht wurde. (orig.)

  1. Characterization of organic thin films

    CERN Document Server

    Ulman, Abraham; Evans, Charles A

    2009-01-01

    Thin films based upon organic materials are at the heart of much of the revolution in modern technology, from advanced electronics, to optics to sensors to biomedical engineering. This volume in the Materials Characterization series introduces the major common types of analysis used in characterizing of thin films and the various appropriate characterization technologies for each. Materials such as Langmuir-Blodgett films and self-assembled monolayers are first introduced, followed by analysis of surface properties and the various characterization technologies used for such. Readers will find detailed information on: -Various spectroscopic approaches to characterization of organic thin films, including infrared spectroscopy and Raman spectroscopy -X-Ray diffraction techniques, High Resolution EELS studies, and X-Ray Photoelectron Spectroscopy -Concise Summaries of major characterization technologies for organic thin films, including Auger Electron Spectroscopy, Dynamic Secondary Ion Mass Spectrometry, and Tra...

  2. Bath atomic composition and deposition time influence on the properties of nanostructured CdS{sub 0.5}Se{sub 0.5} thin films synthesized by CBD

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Ramirez, E.A. [Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, CP 07738 México D.F. (Mexico); Hernandez-Perez, M.A., E-mail: angeleshp@yahoo.com [Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, CP 07738 México D.F. (Mexico); Aguilar-Hernandez, J.R.; Contreras-Puente, G. [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, CP 07738 México D.F. (Mexico)

    2015-09-01

    Chemical Bath Deposition (CBD) was used to grow CdS{sub 1−xf}Se{sub xf} (x{sub f} = 0.5) thin films on Corning glass substrates at 75 °C. The atomic composition of the bath was varied until an x{sub f} of 0.5 was obtained, maintaining the deposition time at 120 min. Then the deposition time was modified from 5 to 360 min. The structural and optical properties of the films were analyzed by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-Ray Diffraction, UV–Vis Spectroscopy, Profilometry and Inductive Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). A bath atomic composition of Cd:S:Se equal to 0.76:0.55:0.45 was employed to obtain a film of x{sub f} = 0.5. The films are constituted by clusters of semispherical nanoparticles (ϕ{sub av} = 15 nm), which are well-arranged in a “nanoworm” structure. The nucleation time of the particles is lower than 5 min. All the films are polycrystalline with hexagonal phase and preferentially orientated on the (002) plane. The crystal size (11–6 nm) and the band gap (2.17–1.99 eV) decrease with the content of Se and remain constant with the deposition time. The composition x{sub f} = 0.5 is achieved at different times to the heterogeneous (60 min) and homogeneous reactions (15 min). The kinetics of deposition and the consumption rate of Se change in a similar way, reaching the stability after 60 min. - Highlights: • CdS{sub 1−x}Se{sub x} ternary alloy thin films with x = 0.5 ± 0.05 can be grown by CBD at 75 °C. • CdS{sub 1−x}Se{sub x} nanocrystals are well arranged in a “worm” structure from 30 min and x ≥ 0.25. • The E{sub g} of (002) oriented hexagonal film is strongly affected by x and crystal size. • Films with x = 0.5 are obtained from 30 min using a Cd:S:Se = 0.76:0.5:0.6 bath ratio. • Consumption rate has the same behavior that growth rate, changing around 60 min.

  3. Interfaces and thin films physics

    International Nuclear Information System (INIS)

    Equer, B.

    1988-01-01

    The 1988 progress report of the Interfaces and Thin Film Physics laboratory (Polytechnic School France) is presented. The research program is focused on the thin films and on the interfaces of the amorphous semiconductor materials: silicon and silicon germanium, silicon-carbon and silicon-nitrogen alloys. In particular, the following topics are discussed: the basic processes and the kinetics of the reactive gas deposition, the amorphous materials manufacturing, the physico-chemical characterization of thin films and interfaces and the electron transport in amorphous semiconductors. The construction and optimization of experimental devices, as well as the activities concerning instrumentation, are also described [fr

  4. Specific features of fullerene-bearing thin film growth using ion beam vacuum sputtering of fullerene mixtures with B, Fe, Se, Gd and Na

    International Nuclear Information System (INIS)

    Semenov, A.P.; Semenova, I.A.; Bulina, N.V.; Lopatin, V.A.; Karmanov, N.S.; Churilov, G.N.

    2005-01-01

    A new approach to the growth of films containing fullerenes and doping elements is described. It is suggested that a cluster mechanism of the target sputtering by accelerated ions makes possible the deposition of fullerenes on a substrate with a certain probability for dopant atoms being introduced into the cavities of fullerene molecules and a higher probability of the doping element introduction between fullerene molecules. The proposed method has been experimentally implemented by using an Ar ion beam to sputter C 60 /C 70 fullerene mixtures, synthesized in a plasmachemical reactor at a pressure of 10 5 Pa and containing a doping element, i.e. Fe, Na, B, Gd or Se. Micron-thick films containing C 60 and C 70 fullerenes and the corresponding dopant element, i.e. Fe, Na, B, Gd or Se, were grown from dopant-containing fullerene mixtures by ion beam sputtering in a vacuum of ∼10 -2 Pa [ru

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

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, Mudhafer Ali [Department of Applied Sciences, University of Technology / Baghdad (Iraq); Jamil, Shatha Shammon Batros [Ministry of Science and Technology / Baghdad (Iraq)

    2013-12-16

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

  6. Nanocrystalline CdS{sub 1−x}Se{sub x} alloys as thin films prepared by chemical bath deposition: Effect of x on the structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Ramirez, E.A. [Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, CP 07738, México D.F. (Mexico); Hernandez-Perez, M.A., E-mail: mhernandezp0606@ipn.mx [Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, CP 07738, México D.F. (Mexico); Aguilar-Hernandez, J. [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, CP 07738, México D.F. (Mexico); Rangel-Salinas, E. [Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, CP 07738, México D.F. (Mexico)

    2014-12-05

    Highlights: • CdS1−xSe{sub x} films with tunable structural and optical properties were grown by CBD. • Thin films are composed by a solid solution of the CdS{sub 1−x}Se{sub x} ternary alloy. • Crystal size, band gap and photoluminescence signal, decrease with the composition. • Ternary alloys show hexagonal phase with preferential orientation on (0 0 2) plane. • Films with x ⩾ 0.5 show semi-spherical grains composed by nanoworms structures. - Abstract: CdS{sub 1−x}Se{sub x} thin films were deposited on Corning glass substrates at 75 °C by chemical bath deposition (CBD) varying the composition “x” from 0 to 1 at a constant deposition time of 120 min. The composition of the films was adjusted by modifying the concentration as well as the ratio of the precursors. The morphological, compositional, structural and optical properties of the films were analyzed using several techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-ray Diffraction (XRD), UV–Vis Spectroscopy (UV–Vis) and Photoluminescence (PL). The films grow as layers following the ion by ion mechanism, the density of the films decreases with x. Films are constituted by clusters (100–600 nm in diameter) of semispherical particles with sizes fluctuating from 10 to 20 nm. For x ⩾ 0.5 the particles are well-arranged in a “worm-like” structure. All the films are polycrystalline, to x = 0 (CdS) the cubic phase is present, the increase of composition promotes the formation of hexagonal phase or a mixture of both cubic and hexagonal phases. Preferential orientation in the (1 0 0) or (0 0 2) plane is observed. The crystal size decreases from 20 to 6 nm when x is increased. The optical properties can be easily tuned by adjusting the composition. Optical absorption analysis shows that the band gap (E{sub g}) value shifts to red in function of x (from 2.47 to 1.99 eV). Photoluminescence signal changes as “x” varies showing a regular behavior

  7. 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.

  8. Site selective doping of Zn for the p-type Cu(In,Ga)Se{sub 2} thin film for solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Shirakata, Sho [Faculty of Engineering, Ehime University, Matsuyama 790-8577 (Japan); Tokyo University of Science, Research Institute for Science and Technology, Noda, Chiba 278-8510 (Japan)

    2017-06-15

    Selective doping of a Zn impurity at the group III site in a Cu(In, Ga)Se{sub 2} (CIGS) film was performed by the doping of Zn at the first stage of the three-stage method. The p-type CIGS:Zn film was obtained, which is in contrast to the n-type CIGS:Zn film obtained by the Zn impurity doping at the second and third-stages. Based on excitation intensity dependence of photoluminescence (PL) at low-temperature, the change in the acceptor level was observed. The enhancement of carrier concentration as a result of Zn-doping in the p-type CIGS:Zn film was observed. The CIGS:Zn solar cells exhibited η of 14.5% and V{sub oc} of 0.658 V, which are higher than that of the corresponding solar cells using the undoped CIGS films. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Influence of different sulfur to selenium ratios on the structural and electronic properties of Cu(In,Ga)(S,Se){sub 2} thin films and solar cells formed by the stacked elemental layer process

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, B. J., E-mail: bjm.mueller@web.de [Robert Bosch GmbH, Corporate Research and Advance Engineering, Advanced Functional Materials and Microsystems, D-70839 Gerlingen (Germany); Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany); Zimmermann, C.; Haug, V., E-mail: veronika.haug@de.bosch.com; Koehler, T.; Zweigart, S. [Robert Bosch GmbH, Corporate Research and Advance Engineering, Advanced Functional Materials and Microsystems, D-70839 Gerlingen (Germany); Hergert, F. [Bosch Solar CISTech GmbH, D-14772 Brandenburg (Germany); Herr, U., E-mail: ulrich.herr@uni-ulm.de [Institute of Micro- and Nanomaterials, University of Ulm, D-89081 Ulm (Germany)

    2014-11-07

    In this study, we investigate the effect of different elemental selenium to elemental sulfur ratios on the chalcopyrite phase formation in Cu(In,Ga)(S,Se){sub 2} thin films. The films are formed by the stacked elemental layer process. The structural and electronic properties of the thin films and solar cells are analyzed by means of scanning electron microscopy, glow discharge optical emission spectrometry, X-ray diffraction, X-ray fluorescence, Raman spectroscopy, spectral photoluminescence as well as current-voltage, and quantum efficiency measurements. The influence of different S/(S+Se) ratios on the anion incorporation and on the Ga/In distribution is investigated. We find a homogenous sulfur concentration profile inside the film from the top surface to the bottom. External quantum efficiency measurements show that the band edge of the solar cell device is shifted to shorter wavelength, which enhances the open-circuit voltages. The relative increase of the open-circuit voltage with S/(S+Se) ratio is lower than expected from the band gap energy trend, which is attributed to the presence of S-induced defects. We also observe a linear decrease of the short-circuit current density with increasing S/(S+Se) ratio which can be explained by a reduced absorption. Above a critical S/(S+Se) ratio of around 0.61, the fill factor drops drastically, which is accompanied by a strong series resistance increase which may be attributed to changes in the back contact or p-n junction properties.

  10. Thin-Film Power Transformers

    Science.gov (United States)

    Katti, Romney R.

    1995-01-01

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

  11. Multiwavelength excitation Raman scattering of Cu2ZnSn(SxSe1−x)4 (0 ≤ x ≤ 1) polycrystalline thin films: Vibrational properties of sulfoselenide solid solutions

    International Nuclear Information System (INIS)

    Dimitrievska, Mirjana; Xie, Haibing; Fairbrother, Andrew; Fontané, Xavier; Saucedo, Edgardo; Izquierdo-Roca, Victor; Gurieva, Galina; 2UB, Departament d'Electrònica, Universitat de Barcelona, C. Martí i Franquès 1, 08028 Barcelona (Spain))" data-affiliation=" (Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1 2pl., 08930 Sant Adrià del Besòs, Barcelona (Spain); IN2UB, Departament d'Electrònica, Universitat de Barcelona, C. Martí i Franquès 1, 08028 Barcelona (Spain))" >Pérez-Rodríguez, Alejandro; Schorr, Susan

    2014-01-01

    In this work, Raman spectroscopy and X-ray diffraction were applied together to evaluate the crystal structure and the phonon modes of photovoltaic grade Cu 2 ZnSn(S x Se 1−x ) 4 thin films, leading to a complete characterization of their structural and vibrational properties. Vibrational characterization has been based on Raman scattering measurements performed with different excitation wavelengths and polarization configurations. Analysis of the experimental spectra has permitted identification of 19 peaks, which positions are in good accord with theoretical predictions. Besides, the observation of Cu 2 ZnSnS 4 -like A symmetry peaks related to S vibrations and Cu 2 ZnSnSe 4 -like A symmetry peaks related to Se vibrations, additional Raman peaks, characteristic of the solid solution and previously not reported, are observed, and are attributed to vibrations involving both S and Se anions.

  12. Bandgap engineering by substitution of S by Se in nanostructured ZnS1-xSex thin films grown by soft chemical route for nontoxic optoelectronic device applications

    International Nuclear Information System (INIS)

    Sadekar, Harishchandra K.; Ghule, Anil Vithal; Sharma, Ramphal

    2011-01-01

    Highlights: → ZnS 1-x Se x (x = 0 to 1) thin films are successfully deposited on glass substrates by soft chemical route. → Structural, optical and electrical properties are studied. → Change in band gap, crystallite size and resistivity is noted with change in S:Se ratio. → Wide band gap material (ZnS 1-x Se x ) is useful for photosensor and solar cell applications. → It utilizes whole visible light spectrum and is a best alternative to conventionally used toxic CdS. - Abstract: Thin films of nanostructured ZnS 1-x Se x with optimized growth parameters were prepared by soft chemical route on glass substrates. Ammonia free precursors were used at 80 deg. C constant bath temperature. The ratio of sulphur to selenium was changed continuously by changing the composition x (0-1), while atomic concentration of zinc was kept constant. Structure, composition and surface morphology of as-deposited films were characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX) and scanning electron microscopy (SEM), atomic force microscopy (AFM) respectively. XRD studies revealed that as-deposited films were nanostructured in nature with cubic zinc blended structure. It was further observed that the preferred orientations are along (1 1 1) plane and crystallite size decreased with increase in the value of x. SEM and AFM images revealed that films were uniform and pinhole free. The optical band gap (E g ) was calculated from the observed transmittance spectra by Urbach method. It was found that the band gap varied linearly from 3.71 to 2.70 eV, as composition x varies 0-1. The electrical properties' study revealed that the decrease in resistivity and increase in photosensitivity, as composition x varied 0-1. The observed interesting properties of ZnS 1-x Se x thin films justified their significance in optoelectronic device fabrication and applications, and as an environment friendly alternative to the commonly used toxic material such as CdS.

  13. Size effects in thin films

    CERN Document Server

    Tellier, CR; Siddall, G

    1982-01-01

    A complete and comprehensive study of transport phenomena in thin continuous metal films, this book reviews work carried out on external-surface and grain-boundary electron scattering and proposes new theoretical equations for transport properties of these films. It presents a complete theoretical view of the field, and considers imperfection and impurity effects.

  14. Photoinduced crystallization and space charge limited current through Au/Se92.7S7.3/Au thin films

    International Nuclear Information System (INIS)

    EL-Barry, A.M.A.

    2007-01-01

    The present paper reports a study of photoinduced crystallization in thermally evaporated Se 92.7 S 7.3 films. The photoinduced crystallization was achieved by shining white light (from 25 mW/cm 2 tungsten lamp) at room temperature for different exposure times up to 5.184 Ms. The analysis of X-ray diffraction (XRD) patterns indicated that the grain size (D), the strain (ζ) and the dislocation density (δ) are photoaging dependent. The capacitance-voltage data confirmed that the relative permittivity of the films is equal to ∼10.31. Room temperature current density voltage characteristics of Au/Se 92.7 S 7.3 /Au films showed Ohmic conduction in the lower voltage range ∼<1 V, and space charge limited conductivity (SCLC) in the relatively high-voltage range. The SCLC was controlled by an exponential distribution of traps above the valence band. The temperature dependence of the current density in accordance with the theory for the exponential trap distributions allowed the calculation of some essential parameters such as; trap concentration, characteristic temperature, and the trap density

  15. Characterization of the structural and optical properties of CuIn{sub 1−x}Ga{sub x}Se{sub 2} QJ;thin films by X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ya-Fen, E-mail: yfwu@mail.mcut.edu.tw [Department of Electronic Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan (China); Hsu, Hung-Pin [Department of Electronic Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan (China); Chen, Hung-Ing [Department of Electronic Engineering, Chang Gung University, Taoyuan 333, Taiwan (China)

    2013-10-15

    The structural and optical properties of Cu-poor CuIn{sub 1−x}Ga{sub x}Se{sub 2} thin films with different gallium contents grown using the co-evaporated technique were studied. Measurements of X-ray diffraction (XRD), temperature-dependent photoluminescence (PL), and photoreflectance (PR) were performed on the samples. The emission peaks in the PL spectra and PR spectra observed around 1.0–1.2 eV are attributed to donor–acceptor pairs and defect-related luminescence. With increasing gallium content, the linewidths of the luminescence spectra for the samples become wider, which we attribute to greater statistical disordering between indium and gallium. The structural properties of the CuIn{sub 1−x}Ga{sub x}Se{sub 2} thin films are further characterized by simulation of the XRD spectra with a theoretical model. It is found that the sample with higher gallium content exhibits less uniformity of microstructure size. The X-ray diffraction line profile analysis also shows a stronger internal strain in the sample with the higher gallium content, which is consistent with its broader microstructure size distribution. The conversion efficiency of the CuIn{sub 1−x}Ga{sub x}Se{sub 2}-based solar cells is also obtained and investigated through theoretical analysis. The experimental results coincide with the inferences given by the X-ray diffraction line profile analysis. -- Highlights: • Co-evaporated CuIn{sub 1−x}Ga{sub x}Se{sub 2} thin films with different gallium contents were studied. • XRD line profiles from the samples are analyzed by a theoretical model. • Less size uniformity and higher internal strain are obtained for high gallium sample. • The efficiency of CIGS solar cells is investigated through theoretical analysis. • The inferences from XRD spectra analysis coincide with experimental measurements.

  16. Superconducting properties of iron chalcogenide thin films

    Directory of Open Access Journals (Sweden)

    Paolo Mele

    2012-01-01

    Full Text Available Iron chalcogenides, binary FeSe, FeTe and ternary FeTexSe1−x, FeTexS1−x and FeTe:Ox, are the simplest compounds amongst the recently discovered iron-based superconductors. Thin films of iron chalcogenides present many attractive features that are covered in this review, such as: (i easy fabrication and epitaxial growth on common single-crystal substrates; (ii strong enhancement of superconducting transition temperature with respect to the bulk parent compounds (in FeTe0.5Se0.5, zero-resistance transition temperature Tc0bulk = 13.5 K, but Tc0film = 19 K on LaAlO3 substrate; (iii high critical current density (Jc ~ 0.5 ×106 A cm2 at 4.2 K and 0 T for FeTe0.5Se0.5 film deposited on CaF2, and similar values on flexible metallic substrates (Hastelloy tapes buffered by ion-beam assisted deposition with a weak dependence on magnetic field; (iv high upper critical field (~50 T for FeTe0.5Se0.5, Bc2(0, with a low anisotropy, γ ~ 2. These highlights explain why thin films of iron chalcogenides have been widely studied in recent years and are considered as promising materials for applications requiring high magnetic fields (20–50 T and low temperatures (2–10 K.

  17. Microstructure characterization of the soda-lime-glass/copper-indium-gallium-selenium interface in Cu-poor Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian, E-mail: wangjustb@gmail.com; Qiao, Yi; Zhu, Jie, E-mail: jiezhu@ustb.edu.cn

    2015-05-29

    The microstructure characteristics of the soda-lime-glass/Cu(In,Ga)Se{sub 2} (SLG/CIGS) interface in Cu-poor CIGS films are investigated by transmission electron microscopy and selected area electronic diffraction (SAED). The SAED patterns show very sharp and strong spots, indicating the main structure of CIGS chalcopyrite. Small dispersed crystals with size distribution from 2 to 5 nm seem to be embedded in amorphous matrix, and additional spots indicate the presence of an ordered vacancy compound (OVC). This observation is consistent with the Raman results, and the OVC phase with the nanoclusters exists in the CIGS matrix, instead of layer structure. Lattice distortion results in local changes in contrast. Some pseudo-disordered structure is observed, however, the structure is actually the chalcopyrite CIGS structure. 180° rotation twins are also observed at the SLG/CIGS interface. Lattice distortion is widely observed at the interface of the Cu-poor CIGS films, and the extra spots could be caused by different lattice orientations. - Highlights: • Cu(In,Ga)Se{sub 2} (CIGS) were prepared on bare soda-lime-glass (SLG) substrates. • Microstructure of the SLG/CIGS interface was investigated. • An ordered vacancy compound (OVC) phase was observed. • The OVC phase with nanoclusters exists in the CIGS matrix, instead of layer structure. • 180° rotation twins were observed at the SLG/CIGS interface.

  18. Spatially resolved photoluminescence and AFM measurements on Cu(In,Ga)Se{sub 2}-based thin film absorbers prepared with different throughput speeds

    Energy Technology Data Exchange (ETDEWEB)

    Meessen, Max; Neumann, Oliver; Heise, Stephan J.; Brueggemann, Rudolf; Bauer, Gottfried H. [Institut fuer Physik, Carl von Ossietzky Universitaet Oldenburg (Germany); Witte, Wolfram; Hariskos, Dimitrios [Zentrum fuer Sonnenenergie- und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), Stuttgart (Germany)

    2011-07-01

    We study the behavior and interdependence of quantities such as photoluminescence (PL) yield, quasi-Fermi level splitting and AFM-determined surface roughness on CIGS thin-film absorbers with different thicknesses between 0.25 and 3 {mu}m achieved by varying the throughput speed in an in-line physical vapor deposition (PVD) process. These quantities are studied on the macroscopic as well as on the microscopic scale with a resolution of approximately 1 {mu}m. It is shown that the structural sizes of the inhomogeneities of the absorber layer itself and its lateral photoluminescence properties decrease with decreasing absorber thickness. These results are compared to those on samples thinned by bromine-methanol etching. Furthermore, we show that varying the thickness of the CdS buffer layer on top of the absorber influences surface recombination and thereby PL yield and quasi-Fermi level splitting. A decrease in surface recombination at higher buffer thicknesses has to be weighed against the increase in absorption in the buffer layer, which in turn decreases carrier generation in the absorber layer.

  19. Superconducting thin films

    International Nuclear Information System (INIS)

    Hebard, A.F.; Vandenberg, J.M.

    1982-01-01

    This invention relates to granular metal and metal oxide superconducting films formed by ion beam sputter deposition. Illustratively, the films comprise irregularly shaped, randomly oriented, small lead grains interspersed in an insulating lead oxide matrix. The films are hillock-resistant when subjected to thermal cycling and exhibit unusual josephson-type switching characteristics. Depending on the oxygen content, a film may behave in a manner similar to that of a plurality of series connected josephson junctions, or the film may have a voltage difference in a direction parallel to a major surface of the film that is capable of being switched from zero voltage difference to a finite voltage difference in response to a current larger than the critical current

  20. New Sunshine Project FY 1996 report on the results of development of photovoltaic power generation system commercialization technologies. Research on commercialization of the technologies for production of thin-film photovoltaic cells (Development of fabrication technologies of high-quality CuInSe{sub 2}-based thin-film solar cells); 1996 nendo taiyoko hatsuden system jitsuyoka gijutsu kaihatsu seika hokokusho. Usumaku taiyo denchi seizo gijutsu no jitsuyoka kenkyu (kohinshitsuka gijutsu (CuInSe{sub 2} taiyo denchi seizo no gijutsu kaihatsu))

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Described herein are the FY 1996 results of development of fabrication technologies for high-quality CuInSe{sub 2}-based photovoltaic cells. The Cu-Ga alloy/In-stacked precursor film is prepared for production of the high-quality thin-film absorber applicable to large-area module fabrication, and selenized by the vapor-phase selenization in a H{sub 2}Se gas atmosphere to produce the thin light-absorbing film in which In and Ga are present at graded concentrations. Increasing Ga alloy content in the CIGS-based thin-film photovoltaic cell fails to widen the forbidden band and improve V{sub oc}, and further optimization works are needed. The method is developed for production of thin-film buffer layer of sulfur-containing Zn compound which can give the cell characteristics equivalent to those of CdS generally used for CIS-based thin-film photovoltaic cell. It is clarified that the photovoltaic cell characteristics can be improved by use of a transparent electroconductive ZnO film of stacked structure, produced by a combination of RF sputtering and DC sputtering. For the patterning technologies necessary for forming series connection on a mini-module, the laser scribing method is applicable to the metal base-electrode, and the mechanical scribing method to the light absorber and window layer. (NEDO)

  1. Beryllium thin films for resistor applications

    Science.gov (United States)

    Fiet, O.

    1972-01-01

    Beryllium thin films have a protective oxidation resistant property at high temperature and high recrystallization temperature. However, the experimental film has very low temperature coefficient of resistance.

  2. Growth of amorphous Zn–Sn–O thin films by RF sputtering for buffer layers of CuInSe2 and SnS solar cells

    International Nuclear Information System (INIS)

    Chang, Shao-Wei; Ishikawa, Kaoru; Sugiyama, Mutsumi

    2015-01-01

    We propose using amorphous Zn–Sn–O (α-ZTO) deposited by RF sputtering as an alternative n-type buffer layer for Cu(In,Ga)Se 2 and SnS solar cells. The order of the carrier density, n, is increased from the order of 10 15 to 10 17 cm −1 as the Sn/(Sn + Zn) atomic ratio increases from 0.29 to 0.40. On the other hand, the order of n decreased from 10 17 to 10 11 cm −1 as the oxygen partial pressure increased from 0 to 10%. Further, for the α-ZTO film with the Sn/(Sn + Zn) atomic ratio at 0.38 and the oxygen partial pressure at 0%, valence band discontinuities of α-ZTO/CuInSe 2 and α-ZTO/SnS were determined using photoelectron yield spectroscopy measurements. The band discontinuities of each of these interfaces form a spike structure in the conduction band offset, which enables a high-performance solar cell to be obtained. - Highlights: • We propose using amorphous Zn–Sn–O as a n-type layer for Cu(In,Ga)Se 2 and SnS solar cells. • The carrier density was controlled by total and/or oxygen partial pressure during sputtering. • Valence band discontinuities of Zn–Sn–O/CuInSe 2 and Zn–Sn–O/SnS were determined. • The conduction band discontinuities of each of these interfaces form a spike structure

  3. Electron-gun Evaporation of Cu and In thin films as Precursors for CuInSe{sub 2} Formation; Evaporacion mediante Canon de Electrones de Laminas Delgadas de Cu e In como Precursores para la Obtencion de CuInSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Caballero, R; Guillen, C

    2001-07-01

    In the present investigation CuInSe{sub 2} is obtained in two stages: sequential evaporation of Cu and In using an electron gun evaporator on substrates up to 30 x 30 cm''2, and a posterior selenization of the deposited films. The study is mainly focused on the first stage, in where the control of the different evaporation parameters of the metal precursors is essential. Electrical measurements are carried out, and also the topography and the thickness are determined with the object of studying the properties and homogeneity of the thin films. (Author) 19 refs.

  4. Electron-gun Evaporation of Cu and In thin films as Precursors for CuInSe{sub 2} Formation; Evaporacion mediante Canon de Electrones de Laminas Delgadas de Cu e In como Precursores para la Obtencion de CuInSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Caballero, R.; Guillen, C.

    2001-07-01

    In the present investigation CuInSe{sub 2} is obtained in two stages: sequential evaporation of Cu and In using an electron gun evaporator on substrates up to 30 x 30 cm''2, and a posterior selenization of the deposited films. The study is mainly focused on the first stage, in where the control of the different evaporation parameters of the metal precursors is essential. Electrical measurements are carried out, and also the topography and the thickness are determined with the object of studying the properties and homogeneity of the thin films. (Author) 19 refs.

  5. Semiconductor-nanocrystal/conjugated polymer thin films

    Science.gov (United States)

    Alivisatos, A. Paul; Dittmer, Janke J.; Huynh, Wendy U.; Milliron, Delia

    2014-06-17

    The invention described herein provides for thin films and methods of making comprising inorganic semiconductor-nanocrystals dispersed in semiconducting-polymers in high loading amounts. The invention also describes photovoltaic devices incorporating the thin films.

  6. Preparation of thin vyns films

    International Nuclear Information System (INIS)

    Blanc, R.; Chedin, P.; Gizon, A.

    1965-01-01

    The fabrication of thin films of VYNS resin (copolymer of chloride and vinyl acetate) of superficial density from 3 to 50 μg/cm 2 with solutions in cyclohexanone is presented. Study and discussion of some properties compared with formvar film (polyvinyl formals). It appears that both can be used as source supports but formvar films are prepared more easily and more quickly, in addition they withstand higher temperatures. The main quality of VYNS is that they can be easily separated even several days after their preparation [fr

  7. Nanocrystal thin film fabrication methods and apparatus

    Science.gov (United States)

    Kagan, Cherie R.; Kim, David K.; Choi, Ji-Hyuk; Lai, Yuming

    2018-01-09

    Nanocrystal thin film devices and methods for fabricating nanocrystal thin film devices are disclosed. The nanocrystal thin films are diffused with a dopant such as Indium, Potassium, Tin, etc. to reduce surface states. The thin film devices may be exposed to air during a portion of the fabrication. This enables fabrication of nanocrystal-based devices using a wider range of techniques such as photolithography and photolithographic patterning in an air environment.

  8. Research on polycrystalline thin-film submodules based on CuInSe{sub 2} materials. Final subcontract report, 11 November 1990--30 June 1995

    Energy Technology Data Exchange (ETDEWEB)

    Arya, R; Fogleboch, J; Kessler, J; Russell, L; Skibo, S; Wiedeman, S [Solarex Corp., Newtown, PA (United States)

    1996-01-01

    This report describes work performed in development of CIS-based photovoltaic (PV) products. The activity began with developing manufacturable deposition methods for all required thin-film layers and developing and understanding processes using those methods. It included demonstrating the potential for high conversion efficiency and followed with developing viable methods for module segment formation and interconnection. These process steps were integrated to fabricate monolithic CIS-based submodules. An important result of this program is the basis of understanding established in developing this material for PV applications, which is necessary to address issues of manufacturability and cost-which were recognized early in the program as being determined by successful solutions to issues of yield, reproducibility, and control as much as by material and energy costs, conversion efficiency, and process speed. Solarex identified at least one absorber formation process that is very robust to shunt formation from pinholes or point defects, tolerant of variation in processing temperature and elemental composition, and is capable of producing high conversion efficiency. This program also allowed development and scale-up of processes for the deposition of all other substrate, heterojunction buffer, and window layers and associated scribing/module formation operations to 1000-CM{sup 2} size. At the completion of this program, Solarex has in place most of the necessary elements to begin the transition to pilot operation of CIS manufacturing activities.

  9. Controlled formation of MoSe{sub 2} by MoN{sub x} thin film as a diffusion barrier against Se during selenization annealing for CIGS solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Chan-Wook [School of Chemical Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Cheon, Taehoon [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Center for Core Research Facilities, DaeguGyeongbuk Institute of Science & Technology, Daegu (Korea, Republic of); Kim, Hangil [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Kwon, Min-Su [School of Chemical Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of); Kim, Soo-Hyun [School of Materials Science and Engineering, Yeungnam University, Gyeongsangbuk-do 712-749 (Korea, Republic of)

    2015-09-25

    Highlights: • Mo/MoN{sub x}/Mo multilayer was investigated as a back contact for CIGS solar cell. • The MoN{sub x} protected the underlying Mo layer during high temperature selenization. • The formation of MoSe{sub 2} layer was precisely controlled. • The diffusion barrier performance of MoN{sub x} against Se was evaluated using TEM analysis. - Abstract: This study investigated the interfacial reactions and electrical properties of a Mo single layer and Mo/MoN{sub x}/Mo multilayer during high temperature selenization annealing. The Mo single layer was converted easily to MoSe{sub 2}, which was 7 times thicker than the Mo layer consumed ∼900 nm, by selenization at 460 °C for 10 min and the sheet resistance increased 8 fold compared to that of the as-deposited Mo film. On the other hand, in the Mo/MoN{sub x}/Mo structure, transmission electron microscopy (TEM) showed that the MoSe{sub 2} transformation was localized only in the top Mo layer and the bottom Mo layer was completely unaffected, even after selenization at 560 °C. The sheet resistance of the multilayer was relatively unchanged by selenization. This suggests that the MoN{sub x} layer performed well as a diffusion barrier against Se and the thickness of MoSe{sub 2} can be controlled precisely by adjusting the top Mo layer thickness. Furthermore, TEM and energy dispersive spectroscopy analysis showed that the selenized multilayer consisted of MoSe{sub 2}/Mo/MoN{sub x}/Mo, in which the top Mo layer of 60 nm was not fully converted to MoSe{sub 2} and 20 nm was left unreacted. The residual Mo interlayer located at the interface of MoSe{sub 2} and MoN{sub x} is believed to be beneficial for the ohmic contact of the selenized multilayer.

  10. High efficiency thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Schock, Hans-Werner [Helmholtz Zentrum Berlin (Germany). Solar Energy

    2012-11-01

    Production of photovoltaics is growing worldwide on a gigawatt scale. Among the thin film technologies, Cu(In,Ga)S,Se{sub 2} (CIS or CIGS) based solar cells have been the focus of more and more attention. This paper aims to analyze the success of CIGS based solar cells and the potential of this technology for future photovoltaics large-scale production. Specific material properties make CIS unique and allow the preparation of the material with a wide range of processing options. The huge potential lies in the possibility to take advantage of modern thin film processing equipment and combine it with very high efficiencies beyond 20% already achieved on the laboratory scale. A sustainable development of this technology could be realized by modifying the materials and replacing indium by abundant elements. (orig.)

  11. Deuterium markers in CdS and Zn(O,S) buffer layers deposited by solution growth for Cu(In,Ga)Se{sub 2} thin-film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Witte, Wolfram; Eicke, Axel; Hariskos, Dimitrios [Zentrum fuer Sonnenenergie und Wasserstoff-Forschung Baden-Wuerttemberg (ZSW), Stuttgart (Germany); Souza, Roger A. de; Martin, Manfred [Institute of Physical Chemistry, RWTH Aachen University (Germany)

    2017-12-15

    This contribution describes an easy and cheap approach to introduce deuterium (D) as an isotopic marker into the commonly used buffer layer materials CdS and Zn(O,S) for Cu(In,Ga)Se{sub 2} (CIGS) thin-film solar cells. D was successfully incorporated during the growth of Zn(O,S) and CdS buffer layers by chemical bath deposition (CBD) with D{sub 2}O. CIGS solar cells prepared with D-containing buffers grown by CBD exhibit power conversion efficiencies above 16%, that is, the D content has no detrimental effect on the performance or other solar cell parameters of the devices. With depth profiles obtained by time-of-flight secondary ion mass spectrometry (ToF-SIMS) we clearly detect the intentionally incorporated D within the solution-grown Zn(O,S) buffer. Assuming that D is present as OD, we compare the amount of OD within the Zn(O,S) layer with the amount of OH on the surface of the subsequent sputtered (Zn,Mg)O layer. Possible applications and future experiments of the method inserting isotopic markers such as D in functional layers of chalcopyrite-type thin-film solar cells and beyond are discussed. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Copper zinc tin sulfide-based thin film solar cells

    CERN Document Server

    Ito, Kentaro

    2014-01-01

    Beginning with an overview and historical background of Copper Zinc Tin Sulphide (CZTS) technology, subsequent chapters cover properties of CZTS thin films, different preparation methods of CZTS thin films, a comparative study of CZTS and CIGS solar cell, computational approach, and future applications of CZTS thin film solar modules to both ground-mount and rooftop installation. The semiconducting compound (CZTS) is made up earth-abundant, low-cost and non-toxic elements, which make it an ideal candidate to replace Cu(In,Ga)Se2 (CIGS) and CdTe solar cells which face material scarcity and tox

  13. Differential in-depth characterization of co-evaporated Cu(In,Ga)Se{sub 2} thin films for solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Klinkert, Torben; Jubault, Marie; Donsanti, Frédérique; Lincot, Daniel; Guillemoles, Jean-François

    2014-05-02

    In this paper we report an alternative approach to perform in-depth characterisation of Cu(In,Ga)Se{sub 2} (CIGS) absorber layers. While usually groups stop their co-evaporation process at different points and analyse the precursor or intermediate phases, we perform in-depth analysis on the finished absorber layer as it will be used in the solar cell. A co-evaporated CIGS layer was cut to several samples, which then were chemically etched to different thicknesses. Compared to sputtering ablation techniques, this avoids the selective abrasion of atoms with different binding energies. The samples were analysed by Raman spectroscopy and X-ray diffraction. In-depth information is obtained by differentiating the signals of samples with different thicknesses after etching and a first order correction for absorption losses was executed. The Ga/(Ga + In) ratio extracted from X-ray diffraction measurements is in good agreement with the double gradient observed by glow discharge optical emission spectroscopy. A slight variation might indicate residual stress in the CIGS layer. A preferred (112) orientation across the whole film together with changing (220), (116) and (312) orientation preferences is reported and explained on the basis of the CIGS crystal structure. Raman signals attributed to ordered vacancy compounds are found throughout the whole sample thickness and not only close to the surface, as often reported in the literature. - Highlights: • Co-evaporated CIGS with double Ga gradient was chemically etched to different thicknesses. • X-ray diffractograms were differentiated to gain in-depth information. • (116)-oriented grains are found to tend to grow on (312)-oriented grains. • Change of preferred orientation was linked to crystal structure at grain boundaries. • Ga gradient from Vegard's law of XRD peaks is in agreement with GDOES measurement.

  14. Thin films of soft matter

    CERN Document Server

    Kalliadasis, Serafim

    2007-01-01

    A detailed overview and comprehensive analysis of the main theoretical and experimental advances on free surface thin film and jet flows of soft matter is given. At the theoretical front the book outlines the basic equations and boundary conditions and the derivation of low-dimensional models for the evolution of the free surface. Such models include long-wave expansions and equations of the boundary layer type and are analyzed via linear stability analysis, weakly nonlinear theories and strongly nonlinear analysis including construction of stationary periodic and solitary wave and similarity solutions. At the experimental front a variety of very recent experimental developments is outlined and the link between theory and experiments is illustrated. Such experiments include spreading drops and bubbles, imbibitions, singularity formation at interfaces and experimental characterization of thin films using atomic force microscopy, ellipsometry and contact angle measurements and analysis of patterns using Minkows...

  15. Review of thin film superconductivity

    International Nuclear Information System (INIS)

    Kihlstrom, K.E.

    1989-01-01

    Advances in thin film superconductivity are critical to the success of many proposed applications. The authors review several of the prominent techniques currently used to produce thin films of the high temperature superconductors including electron beam co-deposition, sputtering (both multiple and composite source configurations) and laser ablation. The authors look at the relevant parameters for each and evaluate the advantages and disadvantages of each technique. In addition, promising work on in situ oxidation is discussed. Also addressed are efforts to find optimum substrate materials and substrate buffer layers for various applications. The current state of the art for T c , J c and H c2 is presented for the yttrium, bismuth, and thallium compounds

  16. Polycrystalline thin films : A review

    Energy Technology Data Exchange (ETDEWEB)

    Valvoda, V [Charles Univ., Prague (Czech Republic). Faculty of Mathematics and Physics

    1996-09-01

    Polycrystalline thin films can be described in terms of grain morphology and in terms of their packing by the Thornton`s zone model as a function of temperature of deposition and as a function of energy of deposited atoms. Grain size and preferred grain orientation (texture) can be determined by X-ray diffraction (XRD) methods. A review of XRD analytical methods of texture analysis is given with main attention paid to simple empirical functions used for texture description and for structure analysis by joint texture refinement. To illustrate the methods of detailed structure analysis of thin polycrystalline films, examples of multilayers are used with the aim to show experiments and data evaluation to determine layer thickness, periodicity, interface roughness, lattice spacing, strain and the size of diffraction coherent volumes. The methods of low angle and high angle XRD are described and discussed with respect to their complementary information content.

  17. Magnetization in permalloy thin films

    Indian Academy of Sciences (India)

    Thin films of permalloy (Ni80Fe20) were prepared using an Ar+N2 mixture with magnetron ... alloys of Ni and Fe) take an important place. NiFe alloy with a ... room temperature (∼298 K, without intentional heating) on Si(100) substrates. A base pressure of 1×10−6 mbar was achieved prior to the deposition. Three different ...

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

    Science.gov (United States)

    Thin-Film Material Science and Processing Thin-Film Material Science and Processing Photo of a , a prime example of this research is thin-film photovoltaics (PV). Thin films are important because cadmium telluride thin film, showing from top to bottom: glass, transparent conducting oxide (thin layer

  19. Nanostructured light-absorbing crystalline CuIn{sub (1–x)}Ga{sub x}Se{sub 2} thin films grown through high flux, low energy ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Hall, Allen J.; Hebert, Damon; Rockett, Angus A. [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, Illinois 61801 (United States); Shah, Amish B. [Center for Microanalysis of Materials, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, 104 South Goodwin Ave, Urbana, Illinois 61801 (United States); Bettge, Martin [Chemical Sciences and Engineering, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60438 (United States)

    2013-10-21

    A hybrid effusion/sputtering vacuum system was modified with an inductively coupled plasma (ICP) coil enabling ion assisted physical vapor deposition of CuIn{sub 1−x}Ga{sub x}Se{sub 2} thin films on GaAs single crystals and stainless steel foils. With <80 W rf power to the ICP coil at 620–740 °C, film morphologies were unchanged compared to those grown without the ICP. At low temperature (600–670 °C) and high rf power (80–400 W), a light absorbing nanostructured highly anisotropic platelet morphology was produced with surface planes dominated by (112){sub T} facets. At 80–400 W rf power and 640–740 °C, both interconnected void and small platelet morphologies were observed while at >270 W and above >715 °C nanostructured pillars with large inter-pillar voids were produced. The latter appeared black and exhibited a strong (112){sub T} texture with interpillar twist angles of ±8°. Application of a negative dc bias of 0–50 V to the film during growth was not found to alter the film morphology or stoichiometry. The results are interpreted as resulting from the plasma causing strong etching favoring formation of (112){sub T} planes and preferential nucleation of new grains, balanced against conventional thermal diffusion and normal growth mechanisms at higher temperatures. The absence of effects due to applied substrate bias suggests that physical sputtering or ion bombardment effects were minimal. The nanostructured platelet and pillar films were found to exhibit less than one percent reflectivity at angles up to 75° from the surface normal.

  20. Photoconductivity of thin organic films

    International Nuclear Information System (INIS)

    Tkachenko, Nikolai V.; Chukharev, Vladimir; Kaplas, Petra; Tolkki, Antti; Efimov, Alexander; Haring, Kimmo; Viheriaelae, Jukka; Niemi, Tapio; Lemmetyinen, Helge

    2010-01-01

    Thin organic films were deposited on silicon oxide surfaces with golden interdigitated electrodes (interelectrode gap was 2 μm), and the film resistivities were measured in dark and under white light illumination. The compounds selected for the measurements include molecules widely used in solar cell applications, such as polythiophene (PHT), fullerene (C 60 ), pyrelene tetracarboxylic diimide (PTCDI) and copper phthalocyanine (CuPc), as well as molecules potentially interesting for photovoltaic applications, e.g. porphyrin-fullerene dyads. The films were deposited using thermal evaporation (e.g. for C 60 and CuPc films), spin coating for PHT, and Langmuir-Schaeffer for the layer-by-layer deposition of porphyrin-fullerene dyads. The most conducting materials in the series are films of PHT and CuPc with resistivities 1.2 x 10 3 Ω m and 3 x 10 4 Ω m, respectively. Under light illumination resistivity of all films decreases, with the strongest light effect observed for PTCDI, for which resistivity decreases by 100 times, from 3.2 x 10 8 Ω m in dark to 3.1 x 10 6 Ω m under the light.

  1. Flexible thin film magnetoimpedance sensors

    International Nuclear Information System (INIS)

    Kurlyandskaya, G.V.; Fernández, E.; Svalov, A.; Burgoa Beitia, A.; García-Arribas, A.; Larrañaga, A.

    2016-01-01

    Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti] 3 /Cu/[FeNi/Ti] 3 films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

  2. Flexible thin film magnetoimpedance sensors

    Energy Technology Data Exchange (ETDEWEB)

    Kurlyandskaya, G.V., E-mail: galina@we.lc.ehu.es [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Fernández, E. [BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Svalov, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Burgoa Beitia, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); García-Arribas, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain)

    2016-10-01

    Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti]{sub 3}/Cu/[FeNi/Ti]{sub 3} films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

  3. Characterization of nanocrystalline cadmium telluride thin films ...

    Indian Academy of Sciences (India)

    Unknown

    tion method, successive ionic layer adsorption and reaction (SILAR), are described. For deposition of CdTe thin films ... By conducting several trials optimization of the adsorption, reaction and rinsing time duration for CdTe thin film .... The electrical resistivity of CdTe films was studied in air. Figure 3 shows the variation of log ...

  4. Thin film solar cell technology in Germany

    International Nuclear Information System (INIS)

    Diehl, W.; Sittinger, V.; Szyszka, B.

    2005-01-01

    Within the scope of limited nonrenewable energy resources and the limited capacity of the ecosystem for greenhouse gases and nuclear waste, sustainability is one important target in the future. Different energy scenarios showed the huge potential for photovoltaics (PV) to solve this energy problem. Nevertheless, in the last decade, PV had an average growth rate of over 20% per year. In 2002, the solar industry delivered more than 500 MWp/year of photovoltaic generators [A. Jaeger-Waldau, A European Roadmap for PV R and D, E-MRS Spring Meeting, (2003)]. More than 85% of the current production involves crystalline silicon technologies. These technologies still have a high cost reduction potential, but this will be limited by the silicon feedstock. On the other hand the so-called second generation thin film solar cells based on a-Si, Cu(In,Ga)(Se,S 2 (CIGS) or CdTe have material thicknesses of a few microns as a result of their direct band gap. Also, the possibility of circuit integration offers an additional cost reduction potential. Especially in Germany, there are a few companies who focus on thin film solar cells. Today, there are two manufacturers with production lines: the Phototronics (PST) division of RWE-Schott Solar with a-Si thin film technology and the former Antec Solar GmbH (now Antec Solar Energy GmbH) featuring the CdTe technology. A pilot line based on CIGS technology is run by Wuerth Solar GmbH. There is also a variety of research activity at other companies, namely, at Shell Solar, Sulfurcell Solartechnik GmbH, Solarion GmbH and the CIS-Solartechnik GmbH. We will give an overview on research activity on various thin film technologies, as well as different manufacturing and production processes in the companies mentioned above. (Author)

  5. Thin films for emerging applications v.16

    CERN Document Server

    Francombe, Maurice H

    1992-01-01

    Following in the long-standing tradition of excellence established by this serial, this volume provides a focused look at contemporary applications. High Tc superconducting thin films are discussed in terms of ion beam and sputtering deposition, vacuum evaporation, laser ablation, MOCVD, and other deposition processes in addition to their ultimate applications. Detailed treatment is also given to permanent magnet thin films, lateral diffusion and electromigration in metallic thin films, and fracture and cracking phenomena in thin films adhering to high-elongation substrates.

  6. Analysis of Hard Thin Film Coating

    Science.gov (United States)

    Shen, Dashen

    1998-01-01

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

  7. Progress in thin film techniques

    International Nuclear Information System (INIS)

    Weingarten, W.

    1996-01-01

    Progress since the last Workshop is reported on superconducting accelerating RF cavities coated with thin films. The materials investigated are Nb, Nb 3 Sn, NbN and NbTiN, the techniques applied are diffusion from the vapour phase (Nb 3 Sn, NbN), the bronze process (Nb 3 Sn), and sputter deposition on a copper substrate (Nb, NbTiN). Specially designed cavities for sample evaluation by RF methods have been developed (triaxial cavity). New experimental techniques to assess the RF amplitude dependence of the surface resistance are presented (with emphasis on niobium films sputter deposited on copper). Evidence is increasing that they are caused by magnetic flux penetration into the surface layer. (R.P.)

  8. High temperature superconductor thin films

    International Nuclear Information System (INIS)

    Correra, L.

    1992-01-01

    Interdisciplinary research on superconducting oxides is the main focus of the contributors in this volume. Several aspects of the thin film field from fundamental properties to applications are examined. Interesting results for the Bi system are also reviewed. The 132 papers, including 8 invited, report mainly on the 1-2-3 system, indicating that the Y-Ba-Cu-O and related compounds are still the most intensively studied materials in this field. The volume attests to the significant progress that has been made in this field, as well as reporting on the challenging problems that still remain to be solved. The papers are presented in five chapters, subsequently on properties, film growth and processing, substrates and multilayers, structural characterization, and applications

  9. Minerals deposited as thin films

    International Nuclear Information System (INIS)

    Vazquez, Cristina; Leyt, D.V. de; Custo, Graciela

    1987-01-01

    Free matrix effects are due to thin film deposits. Thus, it was decided to investigate this technique as a possibility to use pure oxide of the desired element, extrapolating its concentration from analytical curves made with avoiding, at the same time, mathematical corrections. The proposed method was employed to determine iron and titanium concentrations in geological samples. The range studied was 0.1-5%m/m for titanium and 5-20%m/m for iron. For both elements the reproducibility was about 7% and differences between this method and other chemical determinations were 15% for titanium and 7% for iron. (Author) [es

  10. Thin Film Photovoltaic Partnership Project | Photovoltaic Research | NREL

    Science.gov (United States)

    Thin Film Photovoltaic Partnership Project Thin Film Photovoltaic Partnership Project NREL's Thin Film Photovoltaic (PV) Partnership Project led R&D on emerging thin-film solar technologies in the United States from 1994 to 2009. The project made many advances in thin-film PV technologies that allowed

  11. Thin liquid films dewetting and polymer flow

    CERN Document Server

    Blossey, Ralf

    2012-01-01

    This book is a treatise on the thermodynamic and dynamic properties of thin liquid films at solid surfaces and, in particular, their rupture instabilities. For the quantitative study of these phenomena, polymer thin films haven proven to be an invaluable experimental model system.   What is it that makes thin film instabilities special and interesting, warranting a whole book? There are several answers to this. Firstly, thin polymeric films have an important range of applications, and with the increase in the number of technologies available to produce and to study them, this range is likely to expand. An understanding of their instabilities is therefore of practical relevance for the design of such films.   Secondly, thin liquid films are an interdisciplinary research topic. Interdisciplinary research is surely not an end to itself, but in this case it leads to a fairly heterogeneous community of theoretical and experimental physicists, engineers, physical chemists, mathematicians and others working on the...

  12. Synthesis of TiO2-loaded Co0.85Se thin films with heterostructure and their enhanced catalytic activity for p-nitrophenol reduction and hydrazine hydrate decomposition

    International Nuclear Information System (INIS)

    Zuo, Yong; Song, Ji-Ming; Niu, He-Lin; Mao, Chang-Jie; Zhang, Sheng-Yi; Shen, Yu-Hua

    2016-01-01

    P-nitrophenol (4-NP) and hydrazine hydrate are considered to be highly toxic pollutants in wastewater, and it is of great importance to remove them. Herein, TiO 2 -loaded Co 0.85 Se thin films with heterostructure were successfully synthesized by a hydrothermal route. The as-synthesized samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy and selective-area electron diffraction. The results demonstrate that TiO 2 nanoparticles with a size of about 10 nm are easily loaded on the surface of graphene-like Co 0.85 Se nanofilms, and the NH 3  · H 2 O plays an important role in the generation and crystallization of TiO 2 nanoparticles. Brunauer–Emmett–Teller measurement shows that the obtained nanocomposites have a larger specific surface area (199.3 m 2 g −1 ) than that of Co 0.85 Se nanofilms (55.17 m 2 g −1 ) and TiO 2 nanoparticles (19.49 m 2 g −1 ). The catalytic tests indicate Co 0.85 Se–TiO 2 nanofilms have the highest activity for 4-NP reduction and hydrazine hydrate decomposition within 10 min and 8 min, respectively, compared with the corresponding precursor Co 0.85 Se nanofilms and TiO 2 nanoparticles. The enhanced catalytic performance can be attributed to the larger specific surface area and higher rate of interfacial charge transfer in the heterojunction than that of the single components. In addition, recycling tests show that the as-synthesized sample presents stable conversion efficiency for 4-NP reduction. (paper)

  13. Optical properties of Zn{sub 1-x}Mg{sub x}Se epilayers studied by spectroscopy methods[thin films

    Energy Technology Data Exchange (ETDEWEB)

    Glowacki, G; Gapinski, A; Derkowska, B; Bala, W [Institute of Physics, N. Copernicus University, Torun (Poland); Sahraoui, B [Laboratoire des Proprietes Optiques des Materiaux et Applications (POMA), Universite d' Angeres, Angeres (France)

    1998-07-01

    Linear optical properties of Zn{sub 1-x}Mg{sub x}Se (0 {<=} x {<=} 0.4) alloys have been studied using reflectance, spectroscopic ellipsometry and photoluminescence measurements. The refractive indexes of Zn{sub 1-x}Mg{sub x}Se epilayers were investigated as a function of Mg composition (0 {<=} x {<=} 0.4). The energies of band gap E{sub g} and spin-orbit splitting E{sub g} + {delta}, have been determined. These energies are shifted gradually to higher values with increasing Mg content. (author)

  14. Thin film solar cells: research in an industrial perspective.

    Science.gov (United States)

    Edoff, Marika

    2012-01-01

    Electricity generation by photovoltaic conversion of sunlight is a technology in strong growth. The thin film technology is taking market share from the dominant silicon wafer technology. In this article, the market for photovoltaics is reviewed, the concept of photovoltaic solar energy conversion is discussed and more details are given about the present technological limitations of thin film solar cell technology. Special emphasis is given for solar cells which employ Cu(In,Ga)Se(2) and Cu(2)ZnSn(S,Se)(4) as the sunlight-absorbing layer.

  15. Degradation of Cu(In, Ga)Se{sub 2} thin-film solar cells due to the ionization effect of low-energy electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kawakita, Shirou, E-mail: kawakita.shirou@jaxa.jp [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan); Imaizumi, Mitsuru [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan); Ishizuka, Shogo; Shibata, Hajime; Niki, Shigeru [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Okuda, Shuichi [Osaka Prefecture University (OPU), Sakai, Osaka 599-8570 (Japan); Kusawake, Hiroaki [Japan Aerospace Exploration Agency (JAXA), Tsukuba, Ibaraki 305-8505 (Japan)

    2015-05-01

    Cu (In, Ga)Se{sub 2} (CIGS) solar cells were irradiated with 100 keV electrons to reveal the characteristics of created radiation defects. 100 keV electrons cannot produce any displacement defects in CIGS. Low-fluence electrons improve the electrical performance of the CIGS solar cells due to the change in the conductive type of donor to acceptor in a metastable defect, which is equivalent to the light-soaking effect. However, high fluence electrons cause the cell performance to decline. From analysis based on changes in carrier density and electroluminescence, defects causing the decline in performance include donor- and non-radiative types. In addition, red-on-bias experiments showed an increase in III{sub Cu} defects due to electron irradiation. Based on these results, the degradation in the electrical performance of the CIGS solar cells irradiated with high electron fluence would be attributable to a change in the conductive type of III{sub Cu} defects. - Highlights: • Cu(In,Ga)Se2 Solar cells were irradiated with 100 and 250 keV electrons at low temperature. • These electrons degraded the electrical performance of Cu(In,Ga)Se2 sola cells. • The electrons induced ⅢCu defects in Cu(In,Ga)Se2.

  16. Aqueous-Processed Inorganic Thin-Film Solar Cells Based on CdSe(x)Te(1-x) Nanocrystals: The Impact of Composition on Photovoltaic Performance.

    Science.gov (United States)

    Zeng, Qingsen; Chen, Zhaolai; Zhao, Yue; Du, Xiaohang; Liu, Fangyuan; Jin, Gan; Dong, Fengxia; Zhang, Hao; Yang, Bai

    2015-10-21

    Aqueous processed nanocrystal (NC) solar cells are attractive due to their environmental friendliness and cost effectiveness. Controlling the bandgap of absorbing layers is critical for achieving high efficiency for single and multijunction solar cells. Herein, we tune the bandgap of CdTe through the incorporation of Se via aqueous process. The photovoltaic performance of aqueous CdSexTe1-x NCs is systematically investigated, and the impacts of charge generation, transport, and injection on device performance for different compositions are deeply discussed. We discover that the performance degrades with the increasing Se content from CdTe to CdSe. This is mainly ascribed to the lower conduction band (CB) of CdSexTe1-x with higher Se content, which reduces the driving force for electron injection into TiO2. Finally, the performance is improved by mixing CdSexTe1-x NCs with conjugated polymer poly(p-phenylenevinylene) (PPV), and power conversion efficiency (PCE) of 3.35% is achieved based on ternary NCs. This work may provide some information to further optimize the aqueous-processed NC and hybrid solar cells.

  17. Intrinsically conductive polymer thin film piezoresistors

    DEFF Research Database (Denmark)

    Lillemose, Michael; Spieser, Martin; Christiansen, N.O.

    2008-01-01

    We report on the piezoresistive effect in the intrinsically conductive polymer, polyaniline. A process recipe for indirect patterning of thin film polyaniline has been developed. Using a specially designed chip, the polyaniline thin films have been characterised with respect to resistivity...

  18. Excimer Laser Deposition of PLZT Thin Films

    National Research Council Canada - National Science Library

    Petersen, GAry

    1991-01-01

    .... In order to integrate these devices into optical systems, the production of high quality thin films with high transparency and perovskite crystal structure is desired. This requires development of deposition technologies to overcome the challenges of depositing and processing PLZT thin films.

  19. Thin films of mixed metal compounds

    Science.gov (United States)

    Mickelsen, Reid A.; Chen, Wen S.

    1985-01-01

    A compositionally uniform thin film of a mixed metal compound is formed by simultaneously evaporating a first metal compound and a second metal compound from independent sources. The mean free path between the vapor particles is reduced by a gas and the mixed vapors are deposited uniformly. The invention finds particular utility in forming thin film heterojunction solar cells.

  20. Field ion microscope studies on thin films

    International Nuclear Information System (INIS)

    Cavaleru, A.; Scortaru, A.

    1976-01-01

    A review of the progress made in the last years in FIM application to thin film structure studies and adatom properties important in the nucleation stage of thin film growth: substrate binding and mobility of individual adatoms, behaviour of adatoms clusters is presented. (author)

  1. Cellulose triacetate, thin film dielectric capacitor

    Science.gov (United States)

    Yen, Shiao-Ping S. (Inventor); Jow, T. Richard (Inventor)

    1995-01-01

    Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

  2. Nanostructured thin films and coatings functional properties

    CERN Document Server

    Zhang, Sam

    2010-01-01

    The second volume in ""The Handbook of Nanostructured Thin Films and Coatings"" set, this book focuses on functional properties, including optical, electronic, and electrical properties, as well as related devices and applications. It explores the large-scale fabrication of functional thin films with nanoarchitecture via chemical routes, the fabrication and characterization of SiC nanostructured/nanocomposite films, and low-dimensional nanocomposite fabrication and applications. The book also presents the properties of sol-gel-derived nanostructured thin films as well as silicon nanocrystals e

  3. Phonon linewidth due to electron-phonon interactions with strong forward scattering in FeSe thin films on oxide substrates

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yan [Univ. of Tennessee, Knoxville, TN (United States); Rademaker, Louk [Univ. of California, Santa Barbara, CA (United States); Dagotto, Elbio R. [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnston, Steven [Univ. of Tennessee, Knoxville, TN (United States)

    2017-08-18

    Here, the discovery of an enhanced superconducting transition temperature Tc in monolayers of FeSe grown on several oxide substrates has opened a new route to high-Tc superconductivity through interface engineering. One proposal for the origin of the observed enhancement is an electronphonon (e-ph) interaction across the interface that peaked at small momentum transfers. In this paper, we examine the implications of such a coupling on the phononic properties of the system. We show that a strong forward scattering leads to a sizable broadening of phonon lineshape, which may result in charge instabilities at long-wavelengths. However, we further find that the inclusion of Coulombic screening significantly reduces the phonon broadening. Our results show that one might not expect anomalously broad phonon linewidths in the FeSe interface systems, despite the fact that the e-ph interaction has a strong peak in the forward scattering (small \\bfq ) direction.

  4. Behavior of Electrochemically Prepared CuInSe{sub 2} as Photovoltaic Absorber in thin Film Solar Cells; Comportamiento del CuInSe{sub 2} Basado en Precursores Electrodepositados como Absorbente Fotovoltaico en Celulas Solares de Lamina Delgada

    Energy Technology Data Exchange (ETDEWEB)

    Guillen, C; Martinez, M A; Dona, J M; Herrero, J; Gutierrez, M T [Ciemat.Madrid (Spain)

    2000-07-01

    Two different objective have been pursued in the present investigation: (1) optimization of the CuInSe{sub 2} preparation parameters from electrodeposited precursors, and (2) evaluation of their photovoltaic behavior by preparing and enhancing Mo/CuInSe{sub 2}/CdS/TCO devices. When Cu-In-Se precursors are directly electrodeposited, the applied potential fit is essential to improve the photovoltaic performance. Suitable absorbers have been also obtained by evaporing an In layer onto electrodeposited Cu-Se precursors. In this case, the substrate temperature during evaporation determines the CuInSe{sub 2} quality. Similar results have been reached by substituting typical Mo-Coated glass substrates by flexible Mo foils. Different TCO tested (ZnO and ITO) have been found equivalent as front electrical contact in the devices. Solar cell performance can be improved by annealing in air at 200 degree centigree. (Author) 46 refs.

  5. BDS thin film damage competition

    Science.gov (United States)

    Stolz, Christopher J.; Thomas, Michael D.; Griffin, Andrew J.

    2008-10-01

    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  6. Method of producing thin cellulose nitrate film

    International Nuclear Information System (INIS)

    Lupica, S.B.

    1975-01-01

    An improved method for forming a thin nitrocellulose film of reproducible thickness is described. The film is a cellulose nitrate film, 10 to 20 microns in thickness, cast from a solution of cellulose nitrate in tetrahydrofuran, said solution containing from 7 to 15 percent, by weight, of dioctyl phthalate, said cellulose nitrate having a nitrogen content of from 10 to 13 percent

  7. Insights into cadmium diffusion mechanisms in two-stage diffusion profiles in solar-grade Cu(In,Ga)Se{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Biderman, N. J.; Sundaramoorthy, R.; Haldar, Pradeep [Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York 12203 (United States); U.S. Photovoltaic Manufacturing Consortium, Albany, New York 12203 (United States); Novak, Steven W.; Lloyd, J. R. [Colleges of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York 12203 (United States)

    2015-12-07

    Cadmium diffusion experiments were performed on polished copper indium gallium diselenide (Cu(In,Ga)Se{sub 2} or CIGS) samples with resulting cadmium diffusion profiles measured by time-of-flight secondary ion mass spectroscopy. Experiments done in the annealing temperature range between 275 °C and 425 °C reveal two-stage cadmium diffusion profiles which may be indicative of multiple diffusion mechanisms. Each stage can be described by the standard solutions of Fick's second law. The slower cadmium diffusion in the first stage can be described by the Arrhenius equation D{sub 1} = 3 × 10{sup −4} exp (− 1.53 eV/k{sub B}T) cm{sup 2} s{sup −1}, possibly representing vacancy-meditated diffusion. The faster second-stage diffusion coefficients determined in these experiments match the previously reported cadmium diffusion Arrhenius equation of D{sub 2} = 4.8 × 10{sup −4} exp (−1.04 eV/k{sub B}T) cm{sup 2} s{sup −1}, suggesting an interstitial-based mechanism.

  8. Direct band gap measurement of Cu(In,Ga)(Se,S)2 thin films using high-resolution reflection electron energy loss spectroscopy

    International Nuclear Information System (INIS)

    Heo, Sung; Lee, Hyung-Ik; Park, Jong-Bong; Ko, Dong-Su; Chung, JaeGwan; Kim, KiHong; Kim, Seong Heon; Yun, Dong-Jin; Ham, YongNam; Park, Gyeong Su; Song, Taewon; Lee, Dongho; Nam, Junggyu; Kang, Hee Jae; Choi, Pyung-Ho; Choi, Byoung-Deog

    2015-01-01

    To investigate the band gap profile of Cu(In 1−x ,Ga x )(Se 1−y S y ) 2 of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth

  9. Direct band gap measurement of Cu(In,Ga)(Se,S){sub 2} thin films using high-resolution reflection electron energy loss spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Sung [Analytical Engineering Group, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); College of Information and Communication Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of); Lee, Hyung-Ik; Park, Jong-Bong; Ko, Dong-Su; Chung, JaeGwan; Kim, KiHong; Kim, Seong Heon; Yun, Dong-Jin; Ham, YongNam; Park, Gyeong Su [Analytical Engineering Group, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); Song, Taewon [Energy lab, Samsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803 (Korea, Republic of); Lee, Dongho, E-mail: dhlee0333@gmail.com; Nam, Junggyu [PV Development Team, Energy Solution Business Division, Samsung SDI, 467 Beonyeong-ro, Cheonan-si, Chungcheongnam-do 331-330 (Korea, Republic of); Kang, Hee Jae [Department of Physics, Chungbuk National University, Gaesin-dong, Heungdeok-gu, Cheongju, 361-763 (Korea, Republic of); Choi, Pyung-Ho; Choi, Byoung-Deog, E-mail: bdchoi@skku.edu [College of Information and Communication Engineering, Sungkyunkwan University, Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2015-06-29

    To investigate the band gap profile of Cu(In{sub 1−x},Ga{sub x})(Se{sub 1−y}S{sub y}){sub 2} of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth.

  10. Insights into cadmium diffusion mechanisms in two-stage diffusion profiles in solar-grade Cu(In,Ga)Se2 thin films

    International Nuclear Information System (INIS)

    Biderman, N. J.; Sundaramoorthy, R.; Haldar, Pradeep; Novak, Steven W.; Lloyd, J. R.

    2015-01-01

    Cadmium diffusion experiments were performed on polished copper indium gallium diselenide (Cu(In,Ga)Se 2 or CIGS) samples with resulting cadmium diffusion profiles measured by time-of-flight secondary ion mass spectroscopy. Experiments done in the annealing temperature range between 275 °C and 425 °C reveal two-stage cadmium diffusion profiles which may be indicative of multiple diffusion mechanisms. Each stage can be described by the standard solutions of Fick's second law. The slower cadmium diffusion in the first stage can be described by the Arrhenius equation D 1  = 3 × 10 −4  exp (− 1.53 eV/k B T) cm 2  s −1 , possibly representing vacancy-meditated diffusion. The faster second-stage diffusion coefficients determined in these experiments match the previously reported cadmium diffusion Arrhenius equation of D 2  = 4.8 × 10 −4  exp (−1.04 eV/k B T) cm 2  s −1 , suggesting an interstitial-based mechanism

  11. Development of a computer model for polycrystalline thin-film CuInSe sub 2 and CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gray, J.L.; Schwartz, R.J.; Lee, Y.J. (Purdue Univ., Lafayette, IN (United States))

    1992-09-01

    This report describes work to develop an accurate numerical model for CuInSe{sub 2} (CIS) and CdTe-based solar cells capable of running on a personal computer. Such a model will aid researchers in designing and analyzing CIS- and CdTe-based solar cells. ADEPT (A Device Emulation Pregrain and Tool) was used as the basis for this model. An additional objective of this research was to use the models developed to analyze the performance of existing and proposed CIS- and CdTe-based solar cells. The development of accurate numerical models for CIS- and CdTe-based solar cells required the compilation of cell performance data (for use in model verification) and the compilation of measurements of material parameters. The development of the numerical models involved implementing the various physical models appropriate to CIS and CdTe, as well as some common window. A version of the model capable of running on an IBM-comparable personal computer was developed (primary code development is on a SUN workstation). A user-friendly interface with pop-up menus is continuing to be developed for release with the IBM-compatible model.

  12. Measurement of the refractive index dispersion of As2Se3 bulk glass and thin films prior to and after laser irradiation and annealing using prism coupling in the near- and mid-infrared spectral range

    International Nuclear Information System (INIS)

    Carlie, N.; Petit, L.; Musgraves, J. D.; Richardson, K.; Anheier, N. C. Jr.; Qiao, H. A.; Bernacki, B.; Phillips, M. C.

    2011-01-01

    The prism coupling technique has been utilized to measure the refractive index in the near- and mid-IR spectral region of chalcogenide glasses in bulk and thin film form. A commercial system (Metricon model 2010) has been modified with additional laser sources, detectors, and a new GaP prism to allow the measurement of refractive index dispersion over the 1.5-10.6 μm range. The instrumental error was found to be ±0.001 refractive index units across the entire wavelength region examined. Measurements on thermally evaporated AMTIR2 thin films confirmed that (i) the film deposition process provides thin films with reduced index compared to that of the bulk glass used as a target, (ii) annealing of the films increases the refractive index of the film to the level of the bulk glass used as a target to create it, and (iii) it is possible to locally increase the refractive index of the chalcogenide glass using laser exposure at 632.8 nm.

  13. Preparation and characterization of semiconductor thin film cells of n-CdSe and CdSel-x Tex. Application in solar cells of liquid union

    International Nuclear Information System (INIS)

    Gutierrez, M.A.

    1987-01-01

    The development of the new energy sources, constitutes one of the most active and changing investigation areas of nowday. Within this frame, the conservation of photovoltaic solar energy, has taken a particular importance, as these systems become directly the photovoltaic solar energy, which incises on a semiconductor, in electric energy. In spite of this advantage, the use of photovoltaic systems is limited, being the main reason for this, the still high cost of the devices. One of the objectives of this Memory is to contribute to the reduction of these photovoltaic devices by using available methods for the preparation of photosensitive material, and for the union formation. The chosen preparation method is the electrochemical one and the electric field is made up in the interphase semiconductor/electrolyte, dipping the semiconductor in a convenient electrolyte. Summarizing, it can be said that the Memory's objetive presented is to discover the experiences realized in the electrochemical preparation of the n-CdSel-x Tex and its characterization by chemical analysis, X-rays difraction, electronic microscope of swept, optical techniques and photoelectrochemical methods. From the data obtained with these techniques, a study of the physical parameters evolution which determine the photovoltaic properties of the semiconductor, is made, as: the concentration of minoritary carriers, ND, and the diffusion length of these carriers, LP. Finally, taking into account the results obtained by the characterization of n-CdSe and CdSel-x Tex, is made from the construction of the photoelectrochemical cell, using two kinds of electrolyte: sulfide- polysulfide ands ferro-ferricyanide. (Author)

  14. II-I2-IV-VI4 (II = Sr,Ba; I = Cu,Ag; IV = Ge,Sn; VI = S,Se): Earth-Abundant Chalcogenides for Thin Film Photovoltaics

    Science.gov (United States)

    Zhu, Tong; Huhn, William P.; Shin, Donghyeop; Mitzi, David B.; Blum, Volker; Saparov, Bayrammurad

    Chalcogenides such as CdTe, CIGSSe, and CZTSSe are successful for thin film photovoltaics (PV) but contain elements that are rare, toxic, or prone to the formation of detrimental antisite disorder. Recently, the BaCu2SnS4-xSex system has been shown to offer a prospective path to circumvent these problems. While early prototypes show efficiencies of a few percent, many avenues remain to optimize the materials, including the underlying chemical composition. In this work, we explore 16 compounds II-I2-IV-VI4 to help identify new candidate materials for PV, with predictions based on both known experimental and computationally derived structures that belong to five different space groups. We employ hybrid density functional theory (HSE06) to explore the band gap tunability by substituting different elements, and other characteristics such as the effective mass and the absorption coefficient. Compounds containing Cu (rather than Ag) are found to have direct or nearly direct band gaps. Depending on the compound, replacing S with Se leads to a decrease of the predicted band gaps by 0.2-0.8 eV and to somewhat decreasing hole effective masses.

  15. Macro stress mapping on thin film buckling

    Energy Technology Data Exchange (ETDEWEB)

    Goudeau, P.; Villain, P.; Renault, P.-O.; Tamura, N.; Celestre, R.S.; Padmore, H.A.

    2002-11-06

    Thin films deposited by Physical Vapour Deposition techniques on substrates generally exhibit large residual stresses which may be responsible of thin film buckling in the case of compressive stresses. Since the 80's, a lot of theoretical work has been done to develop mechanical models but only a few experimental work has been done on this subject to support these theoretical approaches and nothing concerning local stress measurement mainly because of the small dimension of the buckling (few 10th mm). This paper deals with the application of micro beam X-ray diffraction available on synchrotron radiation sources for stress mapping analysis of gold thin film buckling.

  16. Solid thin film materials for use in thin film charge-coupled devices

    International Nuclear Information System (INIS)

    Lynch, S.J.

    1983-01-01

    Solid thin films deposited by vacuum deposition were evaluated to ascertain their effectiveness for use in the manufacturing of charge-coupled devices (CCDs). Optical and electrical characteristics of tellurium and Bi 2 Te 3 solid thin films were obtained in order to design and to simulate successfully the operation of thin film (TF) CCDs. In this article some of the material differences between single-crystal material and the island-structured thin film used in TFCCDs are discussed. The electrical parameters were obtained and tabulated, e.g. the mobility, conductivity, dielectric constants, permittivity, lifetime of holes and electrons in the thin films and drift diffusion constants. The optical parameters were also measured and analyzed. After the design was complete, experimental TFCCDs were manufactured and were successfully operated utilizing the aforementioned solid thin films. (Auth.)

  17. Passivation Effects in Copper Thin Films

    International Nuclear Information System (INIS)

    Wiederhirn, G.; Nucci, J.; Richter, G.; Arzt, E.; Balk, T. J.; Dehm, G.

    2006-01-01

    We studied the influence of a 10 nm AlxOy passivation on the stress-temperature behavior of 100 nm and 1 μm thick Cu films. At low temperatures, the passivation induces a large tensile stress increase in the 100 nm film; however, its effect on the 1 μm film is negligible. At high temperatures, the opposite behavior is observed; while the passivation does not change the 100 nm film behavior, it strengthens the 1 μm film by driving it deeper into compression. These observations are explained in light of a combination of constrained diffusional creep and dislocation dynamics unique to ultra-thin films

  18. Thermal conductivity model for nanoporous thin films

    Science.gov (United States)

    Huang, Congliang; Zhao, Xinpeng; Regner, Keith; Yang, Ronggui

    2018-03-01

    Nanoporous thin films have attracted great interest because of their extremely low thermal conductivity and potential applications in thin thermal insulators and thermoelectrics. Although there are some numerical and experimental studies about the thermal conductivity of nanoporous thin films, a simplified model is still needed to provide a straightforward prediction. In this paper, by including the phonon scattering lifetimes due to film thickness boundary scattering, nanopore scattering and the frequency-dependent intrinsic phonon-phonon scattering, a fitting-parameter-free model based on the kinetic theory of phonon transport is developed to predict both the in-plane and the cross-plane thermal conductivities of nanoporous thin films. With input parameters such as the lattice constants, thermal conductivity, and the group velocity of acoustic phonons of bulk silicon, our model shows a good agreement with available experimental and numerical results of nanoporous silicon thin films. It illustrates that the size effect of film thickness boundary scattering not only depends on the film thickness but also on the size of nanopores, and a larger nanopore leads to a stronger size effect of the film thickness. Our model also reveals that there are different optimal structures for getting the lowest in-plane and cross-plane thermal conductivities.

  19. A comparative study on charge carrier recombination across the junction region of Cu2ZnSn(S,Se4 and Cu(In,GaSe2 thin film solar cells

    Directory of Open Access Journals (Sweden)

    Mohammad Abdul Halim

    2016-03-01

    Full Text Available A comparative study with focusing on carrier recombination properties in Cu2ZnSn(S,Se4 (CZTSSe and the CuInGaSe2 (CIGS solar cells has been carried out. For this purpose, electroluminescence (EL and also bias-dependent time resolved photoluminescence (TRPL using femtosecond (fs laser source were performed. For the similar forward current density, the EL-intensity of the CZTSSe sample was obtained significantly lower than that of the CIGS sample. Primarily, it can be attributed to the existence of excess amount of non-radiative recombination center in the CZTSSe, and/or CZTSSe/CdS interface comparing to that of CIGS sample. In case of CIGS sample, TRPL decay time was found to increase with the application of forward-bias. This can be attributed to the reduced charge separation rate resulting from the reduced electric-field at the junction. However, in CZTSSe sample, TRPL decay time has been found almost independent under the forward and reverse-bias conditions. This phenomenon indicates that the charge recombination rate strongly dominates over the charge separation rate across the junction of the CZTSSe sample. Finally, temperature dependent VOC suggests that interface related recombination in the CZTSSe solar cell structure might be one of the major factors that affect EL-intensity and also, TRPL decay curves.

  20. A comparative study on charge carrier recombination across the junction region of Cu{sub 2}ZnSn(S,Se){sub 4} and Cu(In,Ga)Se{sub 2} thin film solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Halim, Mohammad Abdul, E-mail: halimtsukuba2012@gmail.com; Islam, Muhammad Monirul; Luo, Xianjia; Sakurai, Takeaki; Akimoto, Katsuhiro [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Sakai, Noriyuki; Kato, Takuya; Sugimoto, Hiroki [Energy Solution Business Center, Showa Shell Sekiyu K.K., Minato, Tokyo 135-8074 (Japan); Tampo, Hitoshi; Shibata, Hajime; Niki, Shigeru [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan)

    2016-03-15

    A comparative study with focusing on carrier recombination properties in Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) and the CuInGaSe{sub 2} (CIGS) solar cells has been carried out. For this purpose, electroluminescence (EL) and also bias-dependent time resolved photoluminescence (TRPL) using femtosecond (fs) laser source were performed. For the similar forward current density, the EL-intensity of the CZTSSe sample was obtained significantly lower than that of the CIGS sample. Primarily, it can be attributed to the existence of excess amount of non-radiative recombination center in the CZTSSe, and/or CZTSSe/CdS interface comparing to that of CIGS sample. In case of CIGS sample, TRPL decay time was found to increase with the application of forward-bias. This can be attributed to the reduced charge separation rate resulting from the reduced electric-field at the junction. However, in CZTSSe sample, TRPL decay time has been found almost independent under the forward and reverse-bias conditions. This phenomenon indicates that the charge recombination rate strongly dominates over the charge separation rate across the junction of the CZTSSe sample. Finally, temperature dependent V{sub OC} suggests that interface related recombination in the CZTSSe solar cell structure might be one of the major factors that affect EL-intensity and also, TRPL decay curves.

  1. Epitaxy, thin films and superlattices

    International Nuclear Information System (INIS)

    Jagd Christensen, Morten

    1997-05-01

    This report is the result of structural investigations of 3d transition metal superlattices consisting of Fe/V, Cr/Mn, V/Mn and Fe/Mn, and a structural and magnetic study of a series of Ho/Pr alloys. The work includes preparation and characterization of substrates as well as growth of thin films and Fe/V superlattices by molecular beam epitaxy, including in-situ characterization by reflection high energy electron diffraction and Auger electron spectroscopy. Structural characterization has been done by x-ray diffraction and neutron diffraction. The x-ray diffraction experiments have been performed on the rotating copper anode at Risoe, and at synchrotron facilities in Hamburg and Brookhaven, and the neutron scattering was done at the Danish research reactor DR3 at Risoe. In addition to longitudinal scans, giving information about the structural parameters in the modulation direction, non-specular scans were also performed. This type of scans gives information about in-plane orientation and lattice parameters. From the analysis, structural information is obtained about lattice parameters, epitaxial strain, coherence lengths and crystallographic orientation for the superlattice systems, except Fe/Mn superlattices, which could not be modelled. For the Ho/Pr alloys, x-ray magnetic scattering was performed, and the crystal and magnetic structure was investigated. (au)

  2. Epitaxy, thin films and superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Jagd Christensen, Morten

    1997-05-01

    This report is the result of structural investigations of 3d transition metal superlattices consisting of Fe/V, Cr/Mn, V/Mn and Fe/Mn, and a structural and magnetic study of a series of Ho/Pr alloys. The work includes preparation and characterization of substrates as well as growth of thin films and Fe/V superlattices by molecular beam epitaxy, including in-situ characterization by reflection high energy electron diffraction and Auger electron spectroscopy. Structural characterization has been done by x-ray diffraction and neutron diffraction. The x-ray diffraction experiments have been performed on the rotating copper anode at Risoe, and at synchrotron facilities in Hamburg and Brookhaven, and the neutron scattering was done at the Danish research reactor DR3 at Risoe. In addition to longitudinal scans, giving information about the structural parameters in the modulation direction, non-specular scans were also performed. This type of scans gives information about in-plane orientation and lattice parameters. From the analysis, structural information is obtained about lattice parameters, epitaxial strain, coherence lengths and crystallographic orientation for the superlattice systems, except Fe/Mn superlattices, which could not be modelled. For the Ho/Pr alloys, x-ray magnetic scattering was performed, and the crystal and magnetic structure was investigated. (au) 14 tabs.; 58 ills., 96 refs.

  3. Flush Mounting Of Thin-Film Sensors

    Science.gov (United States)

    Moore, Thomas C., Sr.

    1992-01-01

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

  4. Thin film description by wavelet coefficients statistics

    Czech Academy of Sciences Publication Activity Database

    Boldyš, Jiří; Hrach, R.

    2005-01-01

    Roč. 55, č. 1 (2005), s. 55-64 ISSN 0011-4626 Grant - others:GA UK(CZ) 173/2003 Institutional research plan: CEZ:AV0Z10750506 Keywords : thin films * wavelet transform * descriptors * histogram model Subject RIV: BD - Theory of Information Impact factor: 0.360, year: 2005 http://library.utia.cas.cz/separaty/2009/ZOI/boldys-thin film description by wavelet coefficients statistics .pdf

  5. Photoluminescence properties of perovskite multilayer thin films

    Energy Technology Data Exchange (ETDEWEB)

    Macario, Leilane Roberta; Longo, Elson, E-mail: leilanemacario@gmail.com [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil); Mazzo, Tatiana Martelli [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil); Bouquet, Valerie; Deputier, Stephanie; Ollivier, Sophie; Guilloux-Viry, Maryline [Universite de Rennes (France)

    2016-07-01

    Full text: The knowledge of the optical properties of thin films is important in many scientific, technological and industrial applications of thin films such as photoconductivity, solar energy, photography, and numerous other applications [1]. In this study, perovskite type oxides were grown by pulsed laser deposition [2] in order to obtain thin films with applicable optical properties. The LaNiO{sub 3} (LN), BaTiO{sub 3} (BT) and KNbO{sub 3} (KNb) targets were prepared by solid-state reaction. The X-ray Diffraction revealed the presence of the desired phases, containing the elements of interest in the targets and in the thin films that were produced. The LN, BT and KNb thin films were polycrystalline and the corresponding diffraction peaks were indexed in the with JCPDS cards n. 00-033-0711, n. 00-005-0626, and n. 00-009-0156, respectively. The multilayers films were polycrystalline. The majority of the micrographs obtained by scanning electron microscopy presented films with a thickness from 100 to 400 nm. The photoluminescent (PL) emission spectra of thin films show different broad bands that occupies large region of the visible spectrum, ranging from about 300-350 to 600-650 nm of the electromagnetic spectrum. The PL emission is associated with the order-disorder structural, even small structural changes can modify the interactions between electronic states. The structural disorder results in formation of new energy levels in the forbidden region. The proximity or distance of these new energy levels formed in relation to valence band and to the conduction band results in PL spectra located at higher or lower energies. These interactions change the electronic states which can be influenced by defects, particularly the interface defects between the layers of the thin films. The presence of defects results in changes in the broad band matrix intensity and in displacement of the PL emission maximum. (author)

  6. Bath parameter dependence of chemically deposited Copper Selenide thin film

    International Nuclear Information System (INIS)

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

    2004-09-01

    In this article, a low cost chemical bath deposition (CBD) technique has been used for the preparation Of Cu 2-x Se thin films on to glass substrate. Different thin fms (0.2-0.6/μm) were prepared by adjusting the bath parameter like concentration of ammonia, deposition time, temperature of the solution, and the ratios of the mixing composition between copper and selenium in the reaction bath. From these studies, it reveals that at low concentration of ammonia or TEA, the terminal thicknesses of the films are less, which gradually increases with the increase of concentrations and then drop down at still higher concentrations. It has been found that completing the Cu 2+ ions with EA first, and then addition of ammonia yields better results than the reverse process. The film thickness increases with the decrease of value x of Cu 2-x Se. (author)

  7. Structure and density for As23Se67Ge10 amorphous films

    International Nuclear Information System (INIS)

    Shchurova, T.N.; Savchenko, N.D.

    1999-01-01

    The effect of thermal annealing and argon laser irradiation on structure and volume for thin amorphous As 23 Se 67 Ge 10 films deposited by thermal evaporation has been investigated. The short-range structure for the annealed films has been found to be more ordered as compared to the irradiated films. The decrease in film volume under thermal annealing and its increase under laser irradiation have been shown. The changes in film volume have been discussed in the context of non-ergodic model for the amorphous state equilibrium taking into account forces acting from the substrate

  8. Nanosphere lithography applied to magnetic thin films

    Science.gov (United States)

    Gleason, Russell

    Magnetic nanostructures have widespread applications in many areas of physics and engineering, and nanosphere lithography has recently emerged as promising tool for the fabrication of such nanostructures. The goal of this research is to explore the magnetic properties of a thin film of ferromagnetic material deposited onto a hexagonally close-packed monolayer array of polystyrene nanospheres, and how they differ from the magnetic properties of a typical flat thin film. The first portion of this research focuses on determining the optimum conditions for depositing a monolayer of nanospheres onto chemically pretreated silicon substrates (via drop-coating) and the subsequent characterization of the deposited