Structural and optical properties of AgInSe2 films prepared on indium tin oxide substrates

AgInSe2 films were prepared on the indium-tin-oxide (ITO)- coated glass substrates by using thermal evaporation. X-ray diffraction spectra showed that the AglnSe(2) films were preferentially grown along the (112) orientation. The crystal structure was chalcopyrite with lattice constants a = 6.102 angstrom and c = 11.69 angstrom. X-ray photoelectron spectroscopy spectra showed that the as-deposited AglnSe2 film was Ag-rich while the AgInSe2 film annealed at 300 degrees C was In-rich. From the atomic force microscope images, the root-mean-square roughness and the grain size decreased with increasing annealing temperature. The optical energy band gap, measured at room temperature, of the as-deposited AgInSe2 film was 1.76 eV, and it increased to about 1.82 eV upon annealing at 100 similar to 300 degrees C in vacuum. The dynamical behavior of the charged carriers in the AgInSe2 film was investigated by using the photoinduced discharge characteristics technique.