Lattice parameters and optical absorption of Culn1-x Gax Se2 thin films

Thin film polycrystalline solar cells based on Culn1-x Gax Se2 have been fabricated and studied with x values from 0 to 1.0. The lattice parameters, grain size, and band gap were measured. Crystal structure and X-ray data of CuIn1-x Gax Se2 were determined using X-ray diffractometry. These materials had a cubic structure with x > 0.5 and a tetragonal structure with x < 0.5. The lattice constants vary linearly with composition. Grain size was measured using X-ray diffraction where the grain size increased linearly with Ga content. A grain size of 1.83-3.52 fim was observed with x < 0.5, while it increased to 4.53 mo m for x = 0.58.