Effects of postdeposition treatments on surfaces of CdTe/CdS solar cells

Abstract

Soft x ray spectroscopy has been used to follow the effects of postdeposition steps CdCl2 activation and back contact treatment on surfaces and interfaces in CdTe based superstrate solar cells.We find that the CdCl2 activation drives sulfur atoms from the CdS layer toward the back contact but not to its surface. Using atomic force microscopy, we find that both treatments strongly influence the morphology of the Au Cu back contact. The spectroscopic results, in contrast, suggest that CdCl2 activation exhibits a larger impact on the surface composition and chemical structure of the interfaces involved in CdTe solar cells