The Morphology of CdS Thin Films Deposited on SnO2-Coated Glass Substrates

The morphology and microstructure of cadmium sulfide (CdS) thin films are a major concern in the fabrication process of CdTe solar cells. In this work, we investigate the morphology and microstructure of chemical-bath-deposited CBD CdS in order to better understand the growth conditions that give rise to films for optimum device performance. The film morphology was investigated by fieldemission, high-resolution scanning electron microscopy (SEM). The film microstructure was studied by transmission electron microscopy (TEM), while the film’s chemistry was investigated by Auger electron spectroscopy (AES). All films examined exhibited pinholes and discontinuities varying in size and density. This may have a significant impact on cell performance by providing shunt paths between the CdTe and the SnO2. Additionally, the CdS films are heavily faulted, which may partially explain why a high density of planar defects is observed in the CdTe/CdS interface region.