Quantitative SIMS depth profiling of CdTe/CdS/TCO solar cell structure in the back and front side configurations

We report a systematic multi-element study of impurities in CdTe/CdS/TCO/glass solar cell structures by dynamic and quantitative SIMS. The SIMS analysis proceeded from the CdTe free surface to the glass in the back side configuration, and from the TCO free surface (after the glass substrate was removed) through to the CdTe layer in the front side configuration. The data recorded from the back- and the front side throughout the structures were compared and discussed by considering the potential contaminations originating from the starting materials (CdTe, CdS, CdCl2 and Br2-methanol) and the environments used during the growth and processing of the structures. This study shows the direct implication that the growth and treatment steps have on the concentration and distribution of impurities in the solar cell structures.