Real Time Analysis of Magnetron-Sputtered Thin-Film CdTe by Multichannel Spectroscopic Ellipsometry

Abstract

Real time spectroscopic ellipsometry (RTSE) based on rotating-compensator modulation and multichannel detection has been implemented to characterize polycrystalline thin film CdTe deposition for photovoltaic applications. RTSE is capable of providing routine deposition information on substrate temperature T and deposition rate. It is also capable of providing detailed information on the thickness evolution of microstructure and optical properties. In this study, we highlight the differences in nucleation that occur under different CdTe deposition conditions on smooth crystalline Si wafer substrates. Differing behavior in the initial stages of deposition has been observed, ranging from layer-by-layer growth to nucleation and coalescence of 45 Å thick clusters. We also consider the thickness and substrate dependence of the microstructure, comparing depositions on smooth Si wafer and rough thin film Mo substrates.

Model for the amorphous roughening transition in amorphous semiconductor deposition

“…Because similar characteristics in the surface roughness evolution have been observed for widely different semiconductor deposition processes from PECVD to sputtering (see, e.g., [4]), generic models (i.e., those that do not depend on the specific surface chemical mechanisms of the growth process) have been considered in this research. Connections can then made between the generic model that is supported by the data and the specific mechanisms elucidated in the extensive literature on this topic.…”