Multilayer Analysis of the CdTe Solar Cell Structure by Spectroscopic Ellipsometry

In this study, ex situ spectroscopic ellipsometry was applied to investigate the optical properties and structure of the thin film CdTe solar cell and its component layer materials. Dielectric functions have been obtained by SE for all layers of the cell, leading to a reference library for comprehensive ex situ CdTe solar cell analysis. In addition, with a Br₂+methanol layer-by-layer etching treatment, it has been possible to track the optical properties of the CdTe component as a function of depth from the surface and proximity to the CdS/CdTe interface in order to gain a better understanding of the underlying film structure. For evaluation purposes, this approach has also been applied to CdTe films initially deposited on c-Si wafer substrates and later subjected to either (i) thermal annealing or (ii) CdCl₂ treatment in order to track the effects of these processes on CdTe structure throughout the bulk layer thickness