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Thin polycrystalline films of the ordered defect compound CuIn 5 Se 8 and CuInSe 2 are prepared on soda lime glass substrates at temperature 623 K by coevaporation of the constituent elements. X-ray diffraction, scanning electron microscopy and energy dispersive analysis of x-rays are done on the films for structural, morphological and composition determination. The lattice constants and the anion displacements for the compounds are calculated. The deformation parameter values show that the compounds have slightly distorted tetragonal unit cells. Assuming the atomic positions, the x-ray structure factor calculations have been made and the emergence of (110) reflection in the x-ray diffraction pattern of the ordered defect compound CuIn 5 Se 8 is explained. High resistivity measured for the compound film is attributed to the compensated defect levels in it. Hot probe measurements show the conductivity of the films to be n-type. A band gap E g = 1.32 eV is observed for the compound and the increase in band gap compared to E g = 0.98 eV for CuInSe 2 is explained as a consequence of the lowering of the valence band due to weaker Se 15 (p)-Cu 15 (d) repulsion in the defect compound and electronic passivation due to 2V Cu -In Cu pairing.

Tin doped indium oxide thin films were prepared on glass substrates kept at room temperature, by activated reactive evaporation (ARE). Structural, electrical and optical properties were studied for films having different thickness. The resulting films are polycrystalline and show ≈ 90 % transmission in the visible region. Hall effect measurements at room temperature for a film with a nominal thickness of ≈ 350 nm shows a relatively high carrier concentration ≈ 6.3 × 10 20 cm −3 , mobility ≈16 cm 2 V −1 s −1 , with a low resistivity ≈ 1.01×10 −3 Ω cm.

SnSe thin films of thickness 180 nm have been deposited on glass substrates by reactive evaporation at an optimized substrate temperature of 523 ± 5 K and pressure of 10−5 mbar. The as-prepared SnSe thin films are characterized for their structural, optical and electrical properties by various experimental techniques. The p-type conductivity, near-optimum direct band gap, high absorption coefficient and good photosensitivity of the SnSe thin film indicate its suitability for photovoltaic applications. The optical constants, loss factor, quality factor and optical conductivity of the films are evaluated. The results of Hall and thermoelectric power measurements are correlated to determine the density of states, Fermi energy and effective mass of carriers and are obtained as 2.8 × 1017 cm−3, 0.03 eV and 0.05m0 respectively. The high Seebeck coefficient ≈ 7863 μV/K, reasonably good power factor ≈ 7.2 × 10−4 W/(m·K2) and thermoelectric figure of merit ≈ 1.2 observed at 42 K suggests that, on further work, the prepared SnSe thin films can also be considered as a possible candidate for cryogenic thermoelectric applications.

We study the structural, electrical and optical properties of silver selenide thin films prepared by reactive evaporation. From the Hall effect study, at room temperature we find a mobility of 2000 cm 2 V −1 s −1 and a carrier concentration of 10 18 cm −3 . The thermoelectric power is measured from room temperature up to 200 • C. X-ray diffraction indicates that the as-prepared films are polycrystalline in nature. The composition and morphology are determined using energy dispersive x-ray analysis and scanning electron microscopy (SEM). The optical bandgap, which is direct-allowed, is 1.58 eV.

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