Study of the Defect Levels, Electrooptics, and Interface Properties of Polycrystalline CdTe and CdS Thin Films and Their Junction

In this study, the electrical behavior of CdS/CdTe junctions was investigated using deep-level transient spectroscopy (DLTS) and capacitance-voltage (c-v) measurements. The results were then correlated to chemical composition and optical properties (measured by wavelength-scanning ellipsometery) of the CdTe film and the dominant defect states were determined by photoluminescence (PL) emissionmeasured before and after post-deposition CdCl2 treatments. CdTe films used in this study were prepared by electrochemical deposition; (ED), close-spaced sublimation (CSS), and physical vapor deposition (PVD). The chemical and heat treatments are shown to decrease Cd-vacancy levels (PL measurements) and quench majority-carrier deep traps. These treatments, which determine various parameterscrucial to the device performance such as the type and concentration of the; dominant defects and deep levels, greatly affect the device performance by controlling open-circuit voltage.