As a thin film solar cell absorber material, antimony selenide (Sb<sub>2</sub>Se<sub>3</sub>) has become a potential candidate recently because of its unique optical and electrical properties a...As a thin film solar cell absorber material, antimony selenide (Sb<sub>2</sub>Se<sub>3</sub>) has become a potential candidate recently because of its unique optical and electrical properties and easy fabrication method. X-ray photoelectron spectroscopy (XPS) was used to determine the stoichiometry and composition of electroless Sb<sub>2</sub>Se<sub>3</sub> thin films using depth profile studies. The surface layers were analyzed nearly stoichiometric. But the abundant amount of antimony makes the inner layer electrically more conductive.展开更多
CuIn（S,Se）2 thin films were prepared by thermal crystallization of co-sputtered Cu-In alloy precursors in S/Se atmosphere. In-depth compositional uniformity is an important prereq- uisite for obtaining device-qualit...CuIn（S,Se）2 thin films were prepared by thermal crystallization of co-sputtered Cu-In alloy precursors in S/Se atmosphere. In-depth compositional uniformity is an important prereq- uisite for obtaining device-quality CuIn（S,Se）2 absorber thin films. In order to figure out the influence of heat treatments on in-depth composition uniformity of CuIn（S,Se）2 thin films, two kinds of reaction temperature profiles were investigated. One process is ＂one step profile＂, referring to formation of CuIn（S,Se）2 thin films just at elevated temperature （e.g. 500 ℃）. The other is ＂two step profile＂, which allows for slow diffusion of S and Se elements into the alloy precursors at a low temperature before the formation and re-crystallization of CuIn（S,Se）2 thin films at higher temperature （e.g. first 250 ℃ then 500 ℃）. X-ray diffrac- tion studies reveal that there is a discrepancy in the shape of （112） peak. Samples annealed with ＂one step profile＂ have splits on （112） peaks, while samples annealed with ＂two step profile＂ have relatively symmetrical （112） peaks. Grazing incident X-ray diffraction and en- ergy dispersive spectrum measurements of samples successively etched in bromine methanol show that CuIn（S,Se）2 thin films have better in-depth composition uniformity after ＂two step profile＂ annealing. The reaction mechanism during the two thermal processing was also investigated by X-ray diffraction and Raman spectra.展开更多
Anodic oxide films grown on titanium alloy Ti-10V-2Fe-3Al in the solution of sodium tartrate, then sealed in boiling deionised water and calcium acetate solution were observed by using field emission scanning electron...Anodic oxide films grown on titanium alloy Ti-10V-2Fe-3Al in the solution of sodium tartrate, then sealed in boiling deionised water and calcium acetate solution were observed by using field emission scanning electron microscopy （FE-SEM）, and were chemically analysed by using energy dispersive spectroscopy （EDS）. Corrosion behaviour was investigated in a 3.5% sodium chloride solution, using electrochemical impedance spectroscopy （EIS）. The morphology of the anodic oxide films was dependent on the sealing processes. The surface sealed in calcium acetate solution presented a more homogeneous and smooth structure compared with that sealed in boiling deionised water. The corrosion resistance of the oxide films sealed in calcium acetate solution was better than that sealed in boiling deionised water.展开更多
Thin films of copper indium gallium selenide Cu（In,Ga）Se2 （CIGS） were prepared by sequential elemental layer deposition in vacuum at room temperature. The as-deposited films were heated in vacuum for compound form...Thin films of copper indium gallium selenide Cu（In,Ga）Se2 （CIGS） were prepared by sequential elemental layer deposition in vacuum at room temperature. The as-deposited films were heated in vacuum for compound formation, and were studied at temperature as high as 1250℃ for the first time. These films were concurrently studied for their structural properties by X-ray diffraction （XRD） technique. The XRD analyses include phase transition studies, grain size variation and microstrain measurements with the reaction temperature and time.It has been observed that there are three distinct regions of variation in all these parameters. These regions belong to three temperature regimes： 〈450℃, 450-950℃, and 〉950℃. It is also seen that the compound formation starts at 250℃, with ternary phases appearing at 350℃ or above. Whereas, there is another phase shift at 950℃ without any preference to the quaternary compound.展开更多
The beneficial effect of the alkali metals such as Na and K on the Cu（In.Ga）Se2 （CIGS） and Cu2ZnSn（S,Se）4 （CZTSSe） solar cells has been extensively investigated in the past two decades, however, in most of the...The beneficial effect of the alkali metals such as Na and K on the Cu（In.Ga）Se2 （CIGS） and Cu2ZnSn（S,Se）4 （CZTSSe） solar cells has been extensively investigated in the past two decades, however, in most of the studies the alkali metals were treated as dopants. Several recent studies have showed that the alkali metals may not only act as dopants but also form secondary phases in the absorber layer or on the surfaces of the films. Using the first-principles calculations, we screened out the most probable secondary phases of Na and K in CIGS and CZTSSe, and studied their electronic structures and optical properties. We found that all these alkali chalcogenide compounds have larger band gaps and lower VBM levels than CIGS and CZTSSe, because the existence of strong p-d coupling in CIS and CZTS pushes the valence band maximum （VBM） level up and reduces the band-gaps, while there is no such p-d coupling in these alkali chalcogenides. This band alignment repels the photo-generated holes from the secondary phases and prevents the electron-hole recombination. Moreover, the study on the optical properties of the secondary phases showed that the absorption coefficients of these alkali chalcogenides are much lower than those of CIGS and CZTSSe in the energy range of 0-3.4eV, which means that the alkali chalcogenides may not influence the absorption of solar light. Since the alkali metal dopants can passivate the grain boundaries and increase the hole carrier concentration, and meanwhile their related secondary phases have innocuous effect on the optical absorption and band alignment, we can understand why the alkali metal dopants can improve the CIGS and CZTSSe solar cell performance.展开更多
Cu(In, Al)Se2 thin films were prepared by electrodeposition from the aqueous solution consisting of CuCl2, InCl3, AlCl3 and SeO2 onto ITO coated glass substrates. The as-deposited films were annealed under vacuum for ...Cu(In, Al)Se2 thin films were prepared by electrodeposition from the aqueous solution consisting of CuCl2, InCl3, AlCl3 and SeO2 onto ITO coated glass substrates. The as-deposited films were annealed under vacuum for 30 min at temperature ranging between 200°C and 400°C. The structural, composition, morphology, optical band gap and electrical resistivity of elaborated thin films were studied, respectively using x-ray diffraction, energy dispersive analysis of x-ray, scanning electron microscopy, UV spectrophotometer and four-point probe method. The lattice constant and structural parameters viz. crystallite size, dislocation density and strain of the films were also calculated. After vacuum annealing, x-ray diffraction results revealed that all films were polycrystalline in nature and exhibit chalcopyrite structure with (112) as preferred orientation. The film annealed at 350°C showed the coexistence of CIASe and InSe phases. The average crystallite size increases linearly with annealing temperature, reaching a maximum value for 350°C. The films show a direct allowed band gap which increases from 1.59 to 1.78 eV with annealing temperature. We have also found that the electrical resistivity of films is controlled by the carrier concentration rather than by their mobility.展开更多
Polycrystalline CuGaSe2 thin films on Mo-coated soda-lime glass substrates have been synthesized by coevaporation process from Cu, Ga and Se sources. Structural and electrical properties of the as-grown CuGaSe2 films ...Polycrystalline CuGaSe2 thin films on Mo-coated soda-lime glass substrates have been synthesized by coevaporation process from Cu, Ga and Se sources. Structural and electrical properties of the as-grown CuGaSe2 films strongly depend on the film composition. Stoichiometric CuGaSe2 is fabricated, as indicated by x-ray diffraction spectroscope （XRD） and x-ray fluorescence （XRF）. A two-phase region is composed of CuGaSe2 and Cu2-xSe phases for Cu-rich films, and CuGaSe2 and CuGa3Se5 phases for Ga-rich films, respectively. Morphological properties are detected by scanning electron microscope （SEM） for various compositional films, the grain sizes of the CuGaSe2films decrease with the extent of deviation from stoichiometric composition. Raman spectroscopy of Cu-rich samples shows that there exist large Cu-Se particles on the film surface. The results from Hall effect measurements for typical samples indicate that CuGaSe2 films are always of p-type semiconductor from Cu-rich to Ga-rich. Stoichiometric CuGaSe2 films exhibit relatively large mobility than any other compositional films. Finally, polycrystalline CuGaSe2 thin film solar cell with a best conversion efficiency of 6.02% has been achieved under the standard air mass （AM）1.5 spectrum for 100mW/cm^2 at room temperature （aperture area, 0.24cm^2）. The open circuit voltage of the CuGaSe2 solar cells is close to770 mV.展开更多
Microwave characteristics of MgB2/Al2O3 superconducting thin films were investigated by coplanar resonator technique. The thin films studied have different grain sizes resulting from different growth techniques. The ...Microwave characteristics of MgB2/Al2O3 superconducting thin films were investigated by coplanar resonator technique. The thin films studied have different grain sizes resulting from different growth techniques. The experimental results can be described very well by a grain-size model which combines coplanar resonator theory and Josephson junction network model. It was found that the penetration depth and surface resistance of thin films with smaller grain sizes are larger than those of thin films with larger grain sizes.展开更多
We present a controlled,stepwise formation of layered semiconductor Bi_(2)O_(2)Se thin films prepared via the vapour process by annealing topological insulator Bi_(2)Se3 thin films in low oxygen atmosphere for differe...We present a controlled,stepwise formation of layered semiconductor Bi_(2)O_(2)Se thin films prepared via the vapour process by annealing topological insulator Bi_(2)Se3 thin films in low oxygen atmosphere for different reactions.Photodetectors based on Bi_(2)O_(2)Se thin film show a responsivity of 1.7×10^(4) A/W at a wavelength of 980 nm.Field-effect transistors based on Bi_(2)O_(2)Se thin film exhibit n-type behavior and present a high electron mobility of 17 cm^(2)/V·s.In addition,the electrical properties of the devices after 4 months keeping in the air shows little change,implying outstanding air-stability of our Bi_(2)O_(2)Se thin films.From the obtained results,it is evident that low oxygen annealing is a surprisingly effective method to fabricate Bi_(2)O_(2)Se thin films for integrated optoelectronic applications.展开更多
We develop a tractable theoretical model to investigate the thermoelectric （TE） transport properties of surface states in topological insulator thin films （TITFs） of Bi2Sea at room temperature. The hybridization b...We develop a tractable theoretical model to investigate the thermoelectric （TE） transport properties of surface states in topological insulator thin films （TITFs） of Bi2Sea 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 Bi2Sea-based TITFs as high-performance TE materials and devices.展开更多
The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS）...The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS） tests. According to the electron density distribution for quasi two-phase mixture doped by spherical nanoparticles, the electron densities in the interfaces of PI/Al2O3 nanocomposite films are evaluated. The trap level density and carrier mobility in the interface are studied. The experimental results show that the distribution and the change rate of the electron density in the three layers of interface are different, indicating different trap distributions in the interface layers. There is a maximum trap level density in the second layer, where the maximum trap level density for the nanocomposite film doped by 25 wt% is 1.054 × 10^22 eV·m^-3 at 1.324eV, resulting in the carrier mobility reducing. In addition, both the thickness and the electron density of the nanocomposite film interface increase with the addition of the doped Al2O3 contents. Through the study on the trap level distribution in the interface, it is possible to further analyze the insulation mechanism and to improve the performance of nano-dielectric materials.展开更多
In this work, the band structure and optical-related properties of CuIn0.5Ga0.5Se2 thin film are presented. The calculation is performed by the full-potential linearized augmented plane wave (FPLAPW) method. The spin-...In this work, the band structure and optical-related properties of CuIn0.5Ga0.5Se2 thin film are presented. The calculation is performed by the full-potential linearized augmented plane wave (FPLAPW) method. The spin-orbit coupling is considered. The result for the dielectric function is in good agreement with earlier experimental measurements and simulations. Based on the complex dielectric function, the dielectric constant, the absorption coefficient, the complex refractive index and the reflectivity at normal incidence are explored. We found that they are comparable with the earlier results.展开更多
High Ga content Cu(In,Ga)Se2 thin films incorporated sulfur were prepared by sequential evaporation from CuGaSe2 and CuInSe2 ternary compounds and subsequently Ga2Se3, In2Se3 and In2S3 binary compounds. The In2S3/(Ga2...High Ga content Cu(In,Ga)Se2 thin films incorporated sulfur were prepared by sequential evaporation from CuGaSe2 and CuInSe2 ternary compounds and subsequently Ga2Se3, In2Se3 and In2S3 binary compounds. The In2S3/(Ga2Se3+ In2Se3) ratio was varied from 0 to 0.13, and the properties of the thin films were investigated. XRD studies demonstrated that the prepared thin films had a chalcopyrite Cu(In,Ga)Se2 structure. The S/(Se+S) mole ratio in the thin films was within the range from 0 to 0.04. The band gaps of Cu(In,Ga)Se2 thin films increased from 1.30 eV to 1.59 eV with increasing the ?In2S3 /(Ga2Se3+ In2Se3) ratio.展开更多
文摘As a thin film solar cell absorber material, antimony selenide (Sb<sub>2</sub>Se<sub>3</sub>) has become a potential candidate recently because of its unique optical and electrical properties and easy fabrication method. X-ray photoelectron spectroscopy (XPS) was used to determine the stoichiometry and composition of electroless Sb<sub>2</sub>Se<sub>3</sub> thin films using depth profile studies. The surface layers were analyzed nearly stoichiometric. But the abundant amount of antimony makes the inner layer electrically more conductive.
文摘CuIn（S,Se）2 thin films were prepared by thermal crystallization of co-sputtered Cu-In alloy precursors in S/Se atmosphere. In-depth compositional uniformity is an important prereq- uisite for obtaining device-quality CuIn（S,Se）2 absorber thin films. In order to figure out the influence of heat treatments on in-depth composition uniformity of CuIn（S,Se）2 thin films, two kinds of reaction temperature profiles were investigated. One process is ＂one step profile＂, referring to formation of CuIn（S,Se）2 thin films just at elevated temperature （e.g. 500 ℃）. The other is ＂two step profile＂, which allows for slow diffusion of S and Se elements into the alloy precursors at a low temperature before the formation and re-crystallization of CuIn（S,Se）2 thin films at higher temperature （e.g. first 250 ℃ then 500 ℃）. X-ray diffrac- tion studies reveal that there is a discrepancy in the shape of （112） peak. Samples annealed with ＂one step profile＂ have splits on （112） peaks, while samples annealed with ＂two step profile＂ have relatively symmetrical （112） peaks. Grazing incident X-ray diffraction and en- ergy dispersive spectrum measurements of samples successively etched in bromine methanol show that CuIn（S,Se）2 thin films have better in-depth composition uniformity after ＂two step profile＂ annealing. The reaction mechanism during the two thermal processing was also investigated by X-ray diffraction and Raman spectra.
基金Supported by the National Natural Science Foundation of China(No.51271012)
文摘Anodic oxide films grown on titanium alloy Ti-10V-2Fe-3Al in the solution of sodium tartrate, then sealed in boiling deionised water and calcium acetate solution were observed by using field emission scanning electron microscopy （FE-SEM）, and were chemically analysed by using energy dispersive spectroscopy （EDS）. Corrosion behaviour was investigated in a 3.5% sodium chloride solution, using electrochemical impedance spectroscopy （EIS）. The morphology of the anodic oxide films was dependent on the sealing processes. The surface sealed in calcium acetate solution presented a more homogeneous and smooth structure compared with that sealed in boiling deionised water. The corrosion resistance of the oxide films sealed in calcium acetate solution was better than that sealed in boiling deionised water.
文摘Thin films of copper indium gallium selenide Cu（In,Ga）Se2 （CIGS） were prepared by sequential elemental layer deposition in vacuum at room temperature. The as-deposited films were heated in vacuum for compound formation, and were studied at temperature as high as 1250℃ for the first time. These films were concurrently studied for their structural properties by X-ray diffraction （XRD） technique. The XRD analyses include phase transition studies, grain size variation and microstrain measurements with the reaction temperature and time.It has been observed that there are three distinct regions of variation in all these parameters. These regions belong to three temperature regimes： 〈450℃, 450-950℃, and 〉950℃. It is also seen that the compound formation starts at 250℃, with ternary phases appearing at 350℃ or above. Whereas, there is another phase shift at 950℃ without any preference to the quaternary compound.
基金supported by the National Natural Science Foundation of China(NSFC)under grant nos.61574059 and 61722402the National Key Research and Development Program of China(2016YFB0700700)+1 种基金Shu-Guang program(15SG20)CC of ECNU
文摘The beneficial effect of the alkali metals such as Na and K on the Cu（In.Ga）Se2 （CIGS） and Cu2ZnSn（S,Se）4 （CZTSSe） solar cells has been extensively investigated in the past two decades, however, in most of the studies the alkali metals were treated as dopants. Several recent studies have showed that the alkali metals may not only act as dopants but also form secondary phases in the absorber layer or on the surfaces of the films. Using the first-principles calculations, we screened out the most probable secondary phases of Na and K in CIGS and CZTSSe, and studied their electronic structures and optical properties. We found that all these alkali chalcogenide compounds have larger band gaps and lower VBM levels than CIGS and CZTSSe, because the existence of strong p-d coupling in CIS and CZTS pushes the valence band maximum （VBM） level up and reduces the band-gaps, while there is no such p-d coupling in these alkali chalcogenides. This band alignment repels the photo-generated holes from the secondary phases and prevents the electron-hole recombination. Moreover, the study on the optical properties of the secondary phases showed that the absorption coefficients of these alkali chalcogenides are much lower than those of CIGS and CZTSSe in the energy range of 0-3.4eV, which means that the alkali chalcogenides may not influence the absorption of solar light. Since the alkali metal dopants can passivate the grain boundaries and increase the hole carrier concentration, and meanwhile their related secondary phases have innocuous effect on the optical absorption and band alignment, we can understand why the alkali metal dopants can improve the CIGS and CZTSSe solar cell performance.
文摘Cu(In, Al)Se2 thin films were prepared by electrodeposition from the aqueous solution consisting of CuCl2, InCl3, AlCl3 and SeO2 onto ITO coated glass substrates. The as-deposited films were annealed under vacuum for 30 min at temperature ranging between 200°C and 400°C. The structural, composition, morphology, optical band gap and electrical resistivity of elaborated thin films were studied, respectively using x-ray diffraction, energy dispersive analysis of x-ray, scanning electron microscopy, UV spectrophotometer and four-point probe method. The lattice constant and structural parameters viz. crystallite size, dislocation density and strain of the films were also calculated. After vacuum annealing, x-ray diffraction results revealed that all films were polycrystalline in nature and exhibit chalcopyrite structure with (112) as preferred orientation. The film annealed at 350°C showed the coexistence of CIASe and InSe phases. The average crystallite size increases linearly with annealing temperature, reaching a maximum value for 350°C. The films show a direct allowed band gap which increases from 1.59 to 1.78 eV with annealing temperature. We have also found that the electrical resistivity of films is controlled by the carrier concentration rather than by their mobility.
基金Project supported by the National High Technology Joint Research Program of China (Grant No 2004AA513020)
文摘Polycrystalline CuGaSe2 thin films on Mo-coated soda-lime glass substrates have been synthesized by coevaporation process from Cu, Ga and Se sources. Structural and electrical properties of the as-grown CuGaSe2 films strongly depend on the film composition. Stoichiometric CuGaSe2 is fabricated, as indicated by x-ray diffraction spectroscope （XRD） and x-ray fluorescence （XRF）. A two-phase region is composed of CuGaSe2 and Cu2-xSe phases for Cu-rich films, and CuGaSe2 and CuGa3Se5 phases for Ga-rich films, respectively. Morphological properties are detected by scanning electron microscope （SEM） for various compositional films, the grain sizes of the CuGaSe2films decrease with the extent of deviation from stoichiometric composition. Raman spectroscopy of Cu-rich samples shows that there exist large Cu-Se particles on the film surface. The results from Hall effect measurements for typical samples indicate that CuGaSe2 films are always of p-type semiconductor from Cu-rich to Ga-rich. Stoichiometric CuGaSe2 films exhibit relatively large mobility than any other compositional films. Finally, polycrystalline CuGaSe2 thin film solar cell with a best conversion efficiency of 6.02% has been achieved under the standard air mass （AM）1.5 spectrum for 100mW/cm^2 at room temperature （aperture area, 0.24cm^2）. The open circuit voltage of the CuGaSe2 solar cells is close to770 mV.
基金Project supported by the National Natural Science Foundation of China （Grant No 10174006）.
文摘Microwave characteristics of MgB2/Al2O3 superconducting thin films were investigated by coplanar resonator technique. The thin films studied have different grain sizes resulting from different growth techniques. The experimental results can be described very well by a grain-size model which combines coplanar resonator theory and Josephson junction network model. It was found that the penetration depth and surface resistance of thin films with smaller grain sizes are larger than those of thin films with larger grain sizes.
基金supported by the Hunan Provincial Natural Science Foundation of China(Grant No.2019JJ40032)。
文摘We present a controlled,stepwise formation of layered semiconductor Bi_(2)O_(2)Se thin films prepared via the vapour process by annealing topological insulator Bi_(2)Se3 thin films in low oxygen atmosphere for different reactions.Photodetectors based on Bi_(2)O_(2)Se thin film show a responsivity of 1.7×10^(4) A/W at a wavelength of 980 nm.Field-effect transistors based on Bi_(2)O_(2)Se thin film exhibit n-type behavior and present a high electron mobility of 17 cm^(2)/V·s.In addition,the electrical properties of the devices after 4 months keeping in the air shows little change,implying outstanding air-stability of our Bi_(2)O_(2)Se thin films.From the obtained results,it is evident that low oxygen annealing is a surprisingly effective method to fabricate Bi_(2)O_(2)Se thin films for integrated optoelectronic applications.
基金Supported by the National Natural Science Foundation of China under Grant No 11304316the Ministry of Science and Technology of China under Grant No 2011YQ130018the Department of Science and Technology of Yunnan Province,and the Chinese Academy of Sciences
文摘We develop a tractable theoretical model to investigate the thermoelectric （TE） transport properties of surface states in topological insulator thin films （TITFs） of Bi2Sea 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 Bi2Sea-based TITFs as high-performance TE materials and devices.
基金Supported by the National Natural Science Foundation of China under Grant Nos 51337002,51077028,51502063 and 51307046the Foundation of Harbin Science and Technology Bureau of Heilongjiang Province under Grant No RC2014QN017034
文摘The distributions of traps and electron density in the interfaces between polyimide （PI） matrix and Al2O3 nanoparticles are researched using the isothermal decay current and the small-angle x-ray scattering （SAXS） tests. According to the electron density distribution for quasi two-phase mixture doped by spherical nanoparticles, the electron densities in the interfaces of PI/Al2O3 nanocomposite films are evaluated. The trap level density and carrier mobility in the interface are studied. The experimental results show that the distribution and the change rate of the electron density in the three layers of interface are different, indicating different trap distributions in the interface layers. There is a maximum trap level density in the second layer, where the maximum trap level density for the nanocomposite film doped by 25 wt% is 1.054 × 10^22 eV·m^-3 at 1.324eV, resulting in the carrier mobility reducing. In addition, both the thickness and the electron density of the nanocomposite film interface increase with the addition of the doped Al2O3 contents. Through the study on the trap level distribution in the interface, it is possible to further analyze the insulation mechanism and to improve the performance of nano-dielectric materials.
文摘In this work, the band structure and optical-related properties of CuIn0.5Ga0.5Se2 thin film are presented. The calculation is performed by the full-potential linearized augmented plane wave (FPLAPW) method. The spin-orbit coupling is considered. The result for the dielectric function is in good agreement with earlier experimental measurements and simulations. Based on the complex dielectric function, the dielectric constant, the absorption coefficient, the complex refractive index and the reflectivity at normal incidence are explored. We found that they are comparable with the earlier results.
文摘High Ga content Cu(In,Ga)Se2 thin films incorporated sulfur were prepared by sequential evaporation from CuGaSe2 and CuInSe2 ternary compounds and subsequently Ga2Se3, In2Se3 and In2S3 binary compounds. The In2S3/(Ga2Se3+ In2Se3) ratio was varied from 0 to 0.13, and the properties of the thin films were investigated. XRD studies demonstrated that the prepared thin films had a chalcopyrite Cu(In,Ga)Se2 structure. The S/(Se+S) mole ratio in the thin films was within the range from 0 to 0.04. The band gaps of Cu(In,Ga)Se2 thin films increased from 1.30 eV to 1.59 eV with increasing the ?In2S3 /(Ga2Se3+ In2Se3) ratio.
