Y. Aparna

Optical absorption studies on p-CuGa0.5In0.5Se2 thin films

The optical absorption spectra of CuGa0.5In0.5Se2 thin films reveal absorption humps which were attributed to valence subband transitions. (αhν)2 vs. photon energy curves indicated a direct fundamental gap of 1.29 eV. Band splitting by crystal-field and spin-orbit effects were observed respectively at 1.39 and 1.58 eV. The crystal-field and spin-orbit parameters were estimated.

Structural, electrical and optical properties of CuGa0.75In0.25Se2 thin films

CuGa0.75In0.25Se2 thin films (0.1-2.0 mu m) grown on Corning 7059 glass substrates at Ts=598-648 K were nearly stoichiometric, single phase, polycrystalline and exhibited electrical resistivity in the range 30-300 Omega cm. Thermoelectric power and Hall effect measurements indicated p-type conduction in the films. The temperature dependence of the electrical conductivity suggested that above 480 K the conduction mechanism was intrinsic, whereas extrinsic/impurity conduction dominated in the range 303-450 K. The optical absorption spectra of CuGa0.75In0.25Se2 thin films revealed absorption humps which were attributed to valence subband transitions. The ( alpha h nu )2 versus photon energy curves indicated a direct fundamental gap of 1.50 eV. Band splitting by crystal-field and spin-orbit effects were observed respectively at 1.57 and 1.75 eV.

Characterization of CuGa0.25In0.75Se2 thin films

Abstract CuGa 0.25 In 0.75 Se 2 thin films prepared by the flash evaporation technique onto Corning 7059 glass substrates at T s = 598–648 K were single phase, nearly stoichiometric and polycrystalline with a strong (112) preferred orientation. The electrical resistivity of the films was in the range 30–350 Ω cm. Thermoelectric power and Hall effect measurements indicated p-type conduction in the films. Optical absorption studies indicated a direct fundamental bandgap of 1.16 eV.

Photovoltaic performance of n-CdS/p-CuGa0.25In0.75Se2 thin film heterojunctions

Abstract Polycrystalline thin film n-CdS/p-CuGa 0.25 In 0.75 Se 2 heterojunctions were fabricated and current density-voltage, capacitance-voltaǵe and spectral response of the junctions were studied. The heterojunction was illuminated in the back-wall configuration and an open-circuit voltage of 500 mV, a short-circuit current density of 23.5 mA cm -2 and an electrical conversion efficiency of 7.6% have been obtained for a cell 1 cm 2 in area under a solar input of 85 mW cm -2 .

Characterization of thin film CuGa0.5In0.5Se2 heterojunctions

Abstract CuGaxIn1−xSe2 is a potential absorber material for the fabrication of heterojunction solar cells. CuGa0.5In0.5Se2 films (0.5–3 μm) growns at Ts = 598–648 K on Corning 7059 glass substrates using the flash evaporation technique were nearly stoichiometric and polycrystalline with a chalcopyrite structure ( a = 5.689 A , c = 11.343 A ). Thermoelectric power and Hall effect measurements indicated p-type conduction in the films. The resistivity and Hall mobility of the films were in the range 50–350ωcm and 2–20 cm2V−1s−1 respectively. Optical absorption studies revealed a direct fundamental band gap of 1.29 eV. Band splitting by crystal field and spin-orbit effects was observed at 1.39 and 1.58 eV respectively. n-CdS/p-CuGa0.5In0.5Se2 thin film heterojunctions were fabricated and current density-voltage, capacitance-voltage and spectral response of the junctions were studied. The heterojunction was illuminated in the back-wall configuration and an open-circuit voltage of 575 mV, a short-circuit current density of 20mA cm−2 and an electrical conversion efficiency of 6.7% have been obtained for a cell 1 cm2 in area under a solar input of 85 mW cm−2.

Characterization of p—CuGa0.25In0.75Se2n—Zn0.35Cd0.65S polycrystalline thin film heterojunctions

Polycrystalline thin film n-Zn 0.35 Cd 0.65 S/p-CuGa 0.25 In 0.75 Se 2 heterojunctions were fabricated and the current density-voltage capacitance-voltage and spectral response characteristics of the junctions were studied. The heterojunction was illuminated in the back-wall configuration and an open-circuit voltage of 425 mV, a short-circuit current density of 30 mA cm -2 and an electrical conversion efficiency of 8.8% have been obtained for a cell with an active area of 1 cm 2 under a solar input of 85 mW cm -2

Characterization of thin film n-CdS/p-CuGa0.5In0.5Se2 heterojunctions

CuGaxIn1−xSe2 is a potential absorber material for the fabrication of heterojunction solar cells. CuGa0.5In0.5Se2 films (0.5–3 μm) grown at Ts = 598–648 K on Corning 7059 glass substrates using the flash evaporation technique were nearly stoichiometric and polycrystalline with a chalcopyrite structure (a = 5.689 A and c = 11.343 A). Thermoelectric power and Hall effect measurements indicated p-type conduction in the films. The resistivity and Hall mobility of the films were in the range 50–350 ohm-cm and 2–20 cm2 V−1 s−1, respectively. The optical absorption studies revealed a direct fundamental band gap of 1.29 eV. Band splitting by crystal-field and spin-orbit effects were observed, respectively, at 1.39 and 1.58 eV. n-CdSp-CuGa0.5In0.5Se2 thin film heterojunctions were fabricated and current density-voltage, capacitance-voltage and spectral response of the junctions were studied. The heterojunction was illuminated in the back-wall configuration and an open-circuit voltage of 575 mV, a short-circuit current density of 20 mA cm−2 and an electrical conversion efficiency of 6.7% have been obtained for a 1 cm2 area cell under a solar input of 85 mW cm−2.

Characterization of n-CdS/p-CuGaxIn1−xSe2 thin film heterojunctions

Abstract CuGa x In 1− xSe 2 is a potential absorber material for the fabrication of heterojunction solar cells. CuGa x In 1− x Se 2 films (0.5−3.0 μm), grown at T s =598−648 K on Corning 7059 glass substrates using the flash evaporation technique, were p-type, nearly stoichiometric and polycrystalline with a chalcopyrite structure. Polycrystalline thin film n-CdS/p-CuGa x In 1− x Se 2 heterojunctions were fabricated with a back-wall configuration and the junction characteristics were evaluated in terms of current density-voltage, capacitance-voltage and spectral response measurements. The electrical conversion efficiency obtained for cells with an active area of 1 cm 2 under a solar input of 85 mW cm −2 was 7.6%, 6.7% and 6.5% respectively for CuGa x In 1− x Se 2 cells with x =0.25, 0.50 and 0.75.

Photovoltaic performance of polycrystalline thin film n-CdS/p-CuGa0.75In0.25Se2 heterojunctions

Abstract Polycrystalline thin film n-CdS/p-CrGa0.75In0.25Se2 heterojunctions were fabricated current density—voltage, capacitance—voltage and spectral response of the junctions were studied. The heterojuntionsf was illuminated in the back-wall configuration and an open-circuit voltage of 700 mV, a short-circuit current density of 1.75 mA cm−2 and an electrical conversion efficiency of 6.5% have been obtained for a 1 cm2 area cell under a solar input of 85 mW cm−2.

Characterization of polycrystalline thin-film n-Zn0.35Cd0.65Sp-CuGa0.75In0.25Se2 heterojunctions

Abstract Polycrystalline thin-film n-Zn 0.35 Cd 0.65 S p-CuGa 0.75 In 0.25 Se 2 heterojunctions were fabricated and current density-voltage, capacitance-voltage and spectral response of the junctions were studied. The heterojunction was illuminated in the back-wall configuration and an open-circuit voltage of 720 mV, a short-circuit current density of 17.75 mA cm −2 and an electrical conversion efficiency of 7.5% have been obtained for a cell with an active area of 1 cm 2 under a solar input of 85 mW cm −2 .