Optical Properties of CuInSe₂ Thin Films Prepared by R.F. Sputtering

Abstract

Abstract The optical absorption of r.f. sputtered CuInSe 2 thin films was studied in the photon energy range from 1 to 3 eV. The gap energy and the spin‐orbit splitting are found to be (1.01 ± 0.01) eV and (0.24 ± 0.02) eV, respectively. From the photon energy dependence of the absorption coefficient it is concluded that the heavy and light hole bands are parabolic whilst the split‐off band contains terms linear in the wavevector. The optical transition probability for valence band‐ to‐ conduction band transitions is estimated to be (10.8 ± 1.0) eV which yields an admixture of copper d states to the valence band of (30 ± 8) %.