Investigation of Physical Properties of e-Beam Evaporated CdTe Thin Films for Photovoltaic Application

CdTe thin films were deposited by electron beam evaporation method. X-ray diffraction, scanning electron microscopy, UV-Vis-NIR spectroscopy and atomic force microscopy (AFM) were used to characterize the films. The results of AFM analysis revealed that the CdTe films have uniform surface. In this research, we have used SnCl_2 heat treatment instead of usual CdCl_2 to determine whether this technique can also assist the re-crystallization of the CdTe layers. CdTe thin films were heat-treated by SnCl_2 solution. Structural analysis using XRD showed that heat treatment by SnCl_2 solution improves thin film crystallinity. A solar cell device was fabricated based on electron beam deposited polycrystalline CdTe and CdS thin film as absorber and window layer on ITO coated soda lime glass as substrate. The electrical characteristics of CdS/CdTe thin film solar cells were investigated under illumination. From the current-voltage characteristics of fabricated device a typical rectifying photovoltaic behavior was obtained.