Electron transport processes in CuIn1−xGaxSe2 films prepared by four source co-evaporation technique

CuIn1−xGaxSe2 (CIGS) (0.05≤x≤0.2) films were synthesized by co-evaporation of elemental materials onto sodalime glass substrates. Electrical and optical properties of the films were studied in the temperature range of 170–380 K. The effect of grain boundary scattering on the electrical transport were examined which indicated grain boundary scattering to play an important role in describing the electron transport processes in these films at lower temperature range. Band gap, refractive index and surface roughness were determined from the analysis of the optical traces (transmittance and reflectance as a function of wavelength) recorded by a spectrophotometer. These results were correlated with the microstructural analysis by SEM and XRD. Photoluminescence (PL) studies were carried out (at 80 and 300 K) for films with different Ga content. The PL spectra were dominated by a strong emission within 1.02–1.19 eV followed by emissions at ∼0.96 and 0.87 eV.