O.Md. Hussain

Photovoltaic performance of p-AgInSe2/n-CdS thin film heterojunctions

Abstract Polycrystalline thin film p-AgInSe 2 /n-CdS 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 500 mV, a short-circuit current density of 24 mA cm −2 and an electrical conversion efficiency of 6% have been obtained for a cell 1 cm 2 in area under a solar input of 100 mW cm −2 .

Structural and optical properties of Cd1−xZnxTe thin films

Abstract Polycrystalline thin films of Cd 1− x Zn x Te ( x = 0.0 to 0.5) deposited by co-evaporation of CdTe and ZnTe in a vacuum better than 5 × 10 −6 Torr on Corning 7059 glass substrates maintained at 300 °C and subsequently annealed in vacuum at 400 °C for 1 h were found to be single-phase and nearly stoichiometric. The structural, electrical and optical properties of these films were studied. The lattice parameter and the optical energy gap in relation to the composition were estimated and the results are discussed in detail.

Characterization of two-source evaporated cadmium zinc telluride thin films

Abstract Thin films of Cd 1− x Zn x Te (0 ≤ x ≤ 1) have been deposited by two-source vacuum evaporation technique onto Corning 7059 glass substrates maintained at 573 K. The structural and optical properties of these films were studied. The composition dependence of the optical band gap for the films was found to be curvi-linear. The wavelength dependence of the refractive index and extinction coefficientof the films was studied. Reflectance spectra of the films exhibited the prominent E 1 . E 1 + Δ 1 and E 2 peak energies of the interband transitions. These peak energies were found to vary linearly with composition of the films.

Investigations on n-CdO/p-CdTe thin film heterojunctions

Abstract n-CdO films were deposited by activated reactive evaporation on Corning 7059 glass substrates maintained at 473 K. p-CdTe films were electron beam evaporated onto n-CdO films at 548 K. A typical Corning 7059 glass/n-CdO/p-CdTe/Cu—Au heterojunction was fabricated and its current-voltage, capacitance-voltage characteristics and spectral response were studied. An electrical conversion efficiency of about 7.7%, with an open-circuit voltage of 695 mV and short-circuit current density of 17.3 mA cm−2, was observed for the cell of an active area of 1 cm2 under a solar input of 85 mW cm−2.

Electrical properties of two-source evaporated polycrystalline films

The compositional dependence of electrical properties such as thermoelectric power, carrier concentration and conductivity, of two-source vacuum evaporated polycrystalline thin films were investigated. The temperature dependence of conductivity was studied in the range 100 - 400 K and the films were found to exhibit two activation energies. Analysis of the activation energy in the low-temperature region led to the conclusion that the electrical conduction might be due to charge carriers in fully ionized trap states of the partially depleted grains, while the conduction in the high-temperature region might be due to thermionic emission of charge carriers from grains.

Investigations on polycrystalline CuGaTe2 thin films

Polycrystalline and single-phase CuGaTe2 thin films(0.4–1.0 μm thickness) were prepared by flashevaporation of the pre-reacted material, synthesized from its constituent elements. The filmswere deposited on glass substrates at temperatures in the range 303–623 K. The physical behaviour of the films was found to be highly influenced by the substrate temperature, T s. The films formed at Ts = 523–573 K were nearly stoichiometric and exhibited (112) preferred orientation with tetragonal structure. The evaluated lattice parameters were a = 6.025 A and c= 11.996 A. The electrical conductivity of the films varied in the range 10-102 ω cm. Two activation energies corresponding to shallow and deep acceptor levels were observed. The films showed a three-fold optical structure with the bandgaps at 1.23 eV, 1.28 eV and 1.98 eV. The optical constants, dielectric constant, plasma frequency and the effective mass of the charge carriers were computed. The results are discussed to study the suitability of CuGaTe2 films for solarcell application.

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-AglnSe2/n-Zn0.35Cd0.65S polycrystalline thin film heterojunctions

Abstract Polycrystalline thin film p -AglnSe 2 / n -Zn 0.35 Cd 0.65 S heterojunctions were fabricated and the current density-voltage, capacitancevoltage 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 7.5% have been obtained for a cell with an active area of 1 cm 2 under a solar input of 100 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.

Investigations on tellurium doped CdTe films deposited by electron beam evaporation

Polycrystalline thin films of stoichiometric CdTe and Te doped high conductivity p-CdTe films have been prepared by an electron beam evaporation technique. The CdTe source material was doped with different Te wt.% and used as the starting material for preparation of p-CdTe films. The effect of Te concentration on structural, electrical and optical properties of the CdTe films were studied.