Optical Properties of Indium - rich Phases in the Cu - In - Se System

Directional freezing method was used to obtain the In - rich phases of the Cu - In - Se system. The crystals with the nominal composition CuIn₃Se₅ (β-phase), CuIn₅Se₈ and CuIn₆Se₁₀ (γ - phase) have been investigated. The crystals were characterized by the optical absorption, photoluminescence and Raman scattering techniques. The band gaps were estimated and their temperature dependence has been found. The photoluminescence spectra have been measured and possible recombination mechanisms are discussed. Raman spectra of two phases are compared. Asymmetric scattering in the layered crystals is observed.