Influence of the Cu Content on Structural and Vibrational Properties in Polycrystalline CuGaSe2 Thin Films

Abstract

AbstractWe studied CuGaSe2 (CGS) thin films with different Cu contents by means of X-ray diffraction (XRD) and micro-Raman spectroscopy. The CGS absorbers were deposited by co-evaporation on Mo/glass substrates. We found a clear shift of the CGS Raman mode frequencies to lower values with increasing Cu/Ga ratio. This is in direct correlation with the increasing lattice constants a and c extracted from XRD patterns. Influence of stress on the obtained results can be neglected, because very small stress values below 50 MPa were determined with the sin2Ψ method.