Optical investigation of a—Ga_<i>x</i>Se_{100–<i>x</i>}thin films

Abstract

Abstract The optical band gap and optical constants have been studied as a function of photon energy for a-Ga x Se100–x thin films (where x × 0, 2.5, 5.0, 7.5 and 10.0) in the wavelength region 450–1000 nm. The optical band gap decreases with the increase of Ga concentration in the a-Ga x Se100–x system. The refractive index (n) decreases while the extinction coefficient (k) increases with increasing photon energy. The results are interpreted in terms of concentration of localized states.