ABSTRACT CdS thin films obtained by chemical bath deposition and annealed in hydrogen and air amb... more ABSTRACT CdS thin films obtained by chemical bath deposition and annealed in hydrogen and air ambients were combined with CdTe absorbers obtained by close spaced sublimation. CdS–CdTe solar cells in superstrate configuration were characterized by current–voltage and quantum efficiency measurements while the analysis of annealed CdS films was made by scanning electron microscopy, X-ray diffraction and UV–vis spectroscopy. It was found that in superstrate configuration, due to the big grains on CdS surface and gas emission from CdS film at high temperature deposition of the absorber, the delamination of layers take place. Annealing in H2 removes the oxygen compounds from CdS grain boundaries and opens them for formation of shortcutting through the CdS layer. The processing in air is most advantageous due to simultaneous presence of chloride and oxygen, contributing to the recrystallization and sintering of the highly textured columnar CdS. The direct influence of the CdS annealing on the solar cell parameters is shown for CdS–CdTe solar cell.
ABSTRACT We examine interface of CdS/CdTe structures after chloride heat treatment•The mechanism ... more ABSTRACT We examine interface of CdS/CdTe structures after chloride heat treatment•The mechanism of the formation of porosity in the CdS/CdTe interface is suggested•Chloride heat treatment causes also recrystallization of CdS•The gap between CdS and CdTe is minimal due to CdO on the grain boundaries of CdS
ABSTRACT Despite numerous theoretical studies on CdTe absorbers with embedded metal nanoparticles... more ABSTRACT Despite numerous theoretical studies on CdTe absorbers with embedded metal nanoparticles (NPs), no technological reports are found. We present an experimental study of 300-nm-thick CdTe absorber layers deposited by close spaced sublimation with incorporated gold NPs to obtain the effect of surface plasmon resonance (SPR). Gold NPs were formed from a HAuCl4 center dot 3H(2)O solution in ethanol and deposited by spin coating or spray pyrolysis on the top of CdTe film. As alternative, sputtering followed by air annealing of gold thin layer was applied to form Au NPs between the glass substrate and the CdTe layer. The properties of these structures were studied by UV-VIS spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The SPR effect was observed in the wavelength region of 570-590 nm for CdTe layers, with Au NPs measuring 30-40 nm in size. At the increased amount of sprayed HAuCl4 center dot 3H(2)O solution the nanoparticles were agglomerated into grains and the SPR peak shifted to longer wavelengths. In the case of spin coating the HAuCl4 solution decomposes on the CdTe surface and by chemical reaction contributed to the substantial removal of the CdTe. Sputtering and spray pyrolysis methods did not change the bulk CdTe layer and introduced the plasmonically enhanced absorption, but led to the formation of additional inter-metallic phases, such as AuCd, Au0.3Te0.7 or AuTe2. The Au0.3Te0.7,7 phase is supposed to play the role of a shell for Au NPs shifting the 592 nm SPR peak to lower wavelengths. Chemical processes responsible for these effects are discussed.
This paper focuses on the photovoltaic parameters of ZnSe/CdTe, CdS/CdTe, and ZnTe/CdTe thin film... more This paper focuses on the photovoltaic parameters of ZnSe/CdTe, CdS/CdTe, and ZnTe/CdTe thin film heterojunction solar cells. ZnSe/CdTe, CdS/CdTe, and ZnTe/CdTe thin film heterojunction solar cells were fabricated by Close Space Sublimation (CSS) on TCO-coated glass substrates. All types of solar cells were fabricated in a superstrate configuration. The thickness of ZnSe and ZnTe layers was varied in order to
CAS 2011 Proceedings (2011 International Semiconductor Conference), 2011
ABSTRACT Electrical conductivity and the Hall-effect are investigated in the temperature interval... more ABSTRACT Electrical conductivity and the Hall-effect are investigated in the temperature interval (80–400) K on thermally annealed in H2 CdS thin films obtained by chemical bath deposition. Different characters of the temperature dependence of conductibility are observed in the CdS films annealed at different temperatures. The Hall measurements allow calculating the values of the NA, ND, nex and ED. According to Hall measurements the CdS films show several donor levels at different energetic depths in dependence of the annealing temperature. The sample annealed at high temperatures than 350°C proves to be compensated with a sharply decreasing electrical conductivity with the temperature decrease.
Differential thermal analysis (DTA) measurements were carried out in order to investigate thermal... more Differential thermal analysis (DTA) measurements were carried out in order to investigate thermal properties of model flux compositions of CdTe-CdCl2 with CdTeO3, the last recognized as a main oxidation product of CdTe. The composition of the flux was ...
ABSTRACT CdS thin films obtained by chemical bath deposition and annealed in hydrogen and air amb... more ABSTRACT CdS thin films obtained by chemical bath deposition and annealed in hydrogen and air ambients were combined with CdTe absorbers obtained by close spaced sublimation. CdS–CdTe solar cells in superstrate configuration were characterized by current–voltage and quantum efficiency measurements while the analysis of annealed CdS films was made by scanning electron microscopy, X-ray diffraction and UV–vis spectroscopy. It was found that in superstrate configuration, due to the big grains on CdS surface and gas emission from CdS film at high temperature deposition of the absorber, the delamination of layers take place. Annealing in H2 removes the oxygen compounds from CdS grain boundaries and opens them for formation of shortcutting through the CdS layer. The processing in air is most advantageous due to simultaneous presence of chloride and oxygen, contributing to the recrystallization and sintering of the highly textured columnar CdS. The direct influence of the CdS annealing on the solar cell parameters is shown for CdS–CdTe solar cell.
ABSTRACT We examine interface of CdS/CdTe structures after chloride heat treatment•The mechanism ... more ABSTRACT We examine interface of CdS/CdTe structures after chloride heat treatment•The mechanism of the formation of porosity in the CdS/CdTe interface is suggested•Chloride heat treatment causes also recrystallization of CdS•The gap between CdS and CdTe is minimal due to CdO on the grain boundaries of CdS
ABSTRACT Despite numerous theoretical studies on CdTe absorbers with embedded metal nanoparticles... more ABSTRACT Despite numerous theoretical studies on CdTe absorbers with embedded metal nanoparticles (NPs), no technological reports are found. We present an experimental study of 300-nm-thick CdTe absorber layers deposited by close spaced sublimation with incorporated gold NPs to obtain the effect of surface plasmon resonance (SPR). Gold NPs were formed from a HAuCl4 center dot 3H(2)O solution in ethanol and deposited by spin coating or spray pyrolysis on the top of CdTe film. As alternative, sputtering followed by air annealing of gold thin layer was applied to form Au NPs between the glass substrate and the CdTe layer. The properties of these structures were studied by UV-VIS spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction. The SPR effect was observed in the wavelength region of 570-590 nm for CdTe layers, with Au NPs measuring 30-40 nm in size. At the increased amount of sprayed HAuCl4 center dot 3H(2)O solution the nanoparticles were agglomerated into grains and the SPR peak shifted to longer wavelengths. In the case of spin coating the HAuCl4 solution decomposes on the CdTe surface and by chemical reaction contributed to the substantial removal of the CdTe. Sputtering and spray pyrolysis methods did not change the bulk CdTe layer and introduced the plasmonically enhanced absorption, but led to the formation of additional inter-metallic phases, such as AuCd, Au0.3Te0.7 or AuTe2. The Au0.3Te0.7,7 phase is supposed to play the role of a shell for Au NPs shifting the 592 nm SPR peak to lower wavelengths. Chemical processes responsible for these effects are discussed.
This paper focuses on the photovoltaic parameters of ZnSe/CdTe, CdS/CdTe, and ZnTe/CdTe thin film... more This paper focuses on the photovoltaic parameters of ZnSe/CdTe, CdS/CdTe, and ZnTe/CdTe thin film heterojunction solar cells. ZnSe/CdTe, CdS/CdTe, and ZnTe/CdTe thin film heterojunction solar cells were fabricated by Close Space Sublimation (CSS) on TCO-coated glass substrates. All types of solar cells were fabricated in a superstrate configuration. The thickness of ZnSe and ZnTe layers was varied in order to
CAS 2011 Proceedings (2011 International Semiconductor Conference), 2011
ABSTRACT Electrical conductivity and the Hall-effect are investigated in the temperature interval... more ABSTRACT Electrical conductivity and the Hall-effect are investigated in the temperature interval (80–400) K on thermally annealed in H2 CdS thin films obtained by chemical bath deposition. Different characters of the temperature dependence of conductibility are observed in the CdS films annealed at different temperatures. The Hall measurements allow calculating the values of the NA, ND, nex and ED. According to Hall measurements the CdS films show several donor levels at different energetic depths in dependence of the annealing temperature. The sample annealed at high temperatures than 350°C proves to be compensated with a sharply decreasing electrical conductivity with the temperature decrease.
Differential thermal analysis (DTA) measurements were carried out in order to investigate thermal... more Differential thermal analysis (DTA) measurements were carried out in order to investigate thermal properties of model flux compositions of CdTe-CdCl2 with CdTeO3, the last recognized as a main oxidation product of CdTe. The composition of the flux was ...
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