Novel method for the determination of the optical conductivity and dielectric constant of SiGe thin films using Kato-Adachi dispersion model

In the present paper, we report a combined experimental and theoretical study of compositionally graded Si1−xGex thin films grown on Si at 550°C. The study has been conducted for two particular values of the Ge fraction x namely x = 0.05 and x = 0.1. This choice finds its origin with the circumstance of getting good material quality by the obtention of totally relaxed layers with dislocation-free, as well as a good thermal conductivity of the active layer. The curves of optical constants and optical conductivity were performed by fitting the experimental ellipsometric spectra. Theoretical results reveal that the layers thickness of all studied samples was about 110 nm, suggesting the accuracy of the new Kato-Adachi spectroscopic ellipsometry model developed herein. Furthermore, current–voltage characteristic disclose that the efficiency of the structure corresponding to the fraction x = 0.1 is higher than the other solar cell due to higher values of Voc and FF.