Effect of selenium evaporation rate on ultrathin Cu(In,Ga)Se2 films

The selenium (Se) rate has been shown to have a significant influence on the deposition of high quality Cu(In,Ga)Se₂ thin films. This has been observed primarily by exsitu experiments on thick Cu(In,Ga)Se₂ films. In this paper, we present the influence of the Se rate on the properties of both thick and ultrathin CIGS films as measured by in-situ real time spectroscopic ellipsometry (RTSE). These measurements were correlated with ex-situ measurements performed by variable angle spectroscopic ellipsometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray fluorescence (XRF) to analyze the crystal structure, surface morphology, composition ratio and the fundamental optical constants of Cu(In,Ga)Se₂ thin films deposited with different Se evaporation rates.