ZnS Films Deposited by ALD for Solar Cell Applications

Abstract

Alternative deposition methods and materials are of interest for the fabrication of thin film solar cells since they offer potential enhancements for either low cost, high speed or high efficiency but also because they can help in better understanding the underlying physical and chemical processes that could lead to the next generation of solar cells. In this study, we will present new results on the deposition of ZnS by atomic layer deposition (ALD) as an alternate to CdS deposited by chemical bath deposition. More specifically, in-situ real time and ex-situ measurements by spectroscopic ellipsometry will be performed, allowing for the analysis of the growth processes as a function of deposition parameters. These measurements also allow for a parameterization of the dielectric functions of ZnS and the evolution of its grain size and band gap as a function of thickness. These measurements will then be correlated with ex-situ measurements, such as XRD, AFM and T&R, which is expected to validate the model used for spectroscopic ellipsometry data analysis.