Post-growth CdCl_2 treatment on CdTe thin films grown on graphene layers using a close-spaced sublimation method

We investigated the morphological, structural and optical properties of CdCl₂-treated cadmium telluride (CdTe) thin films deposited on defective graphene using a close-spaced sublimation (CSS) system. Heat treatment in the presence of CdCl₂ caused recrystallization of CSS-grown CdTe over the as-deposited structures. The preferential (111) orientation of as-deposited CdTe films was randomized after post-growth CdCl₂ treatment. New small grains (bumps) on the surface of CdCl₂-treated CdTe films were ascribed to nucleation of the CdTe grains during the CdCl₂ treatment. The properties of as-deposited and CdCl₂-treated CdTe films were characterized by room temperature micro-photoluminescence, micro-Raman spectroscopy, scanning electron microscopy, and X-ray diffraction analysis. Our results are useful to demonstrate a substrate configuration CdTe thin film solar cells.