Characterization of CuIn(Ga)Se2 Thin Films

Abstract

In-rich CuIn(Ga)Se2 thin films are characterized by optical and electrical measurements. The results are consistently explained in the Shklovskij/Efros model appropriate for highly defective and highly compensated semiconductors. The dominant radiative recombination is of tail-impurity type at low temperatures and low excitation powers, and of band-impurity type at high temperatures and/or high excitation densities. The analysis of the data yields that the impurity content is in the order of 1018 cm—3 while the free carrier (hole) concentration at room temperature is in the order of 1016 cm—3. The impurity density increases with increasing deviation of the Cu/(In+Ga) ratio from stoichiometry.