Cadmium chloride assisted re-crystallization of CdTe: The effect of the annealing temperature

The aim of this investigation is to apply advanced microstructural characterization techniques to study the effects of varying the cadmium chloride annealing temperature on the microstructure of cadmium telluride solar cells deposited by close spaced sublimation (CSS) and relate this to cell performance. A range of techniques have been used to observe the morphological changes to the microstructure as well as the chemical and crystallographic changes as a function of treatment parameters. Electrical tests that link the device performance with the microstructural properties of the cells have also been undertaken. Techniques used include Transmission Electron Microscopy (TEM) for sub-grain analysis, X-ray Photoelectron Spectroscopy (XPS) depth profiles to show the effect of temperature on the diffusion of chlorine into the CdTe. Grain orientation data as well as grain size change has been obtained using Electron Backscatter Diffraction (EBSD) on Focused Ion Beam (FIB) prepared planar sections.