Sodium diffusion, selenization, and microstructural effects associated with various molybdenum back contact layers for CIS-based solar cells

By varying the argon pressure during deposition, the authors have prepared a set of sputtered molybdenum films on soda-lime glass substrates with a range of mechanical and electrical properties. These films were subsequently exposed to several of the processing steps used in the fabrication of copper-indium-diselenide (CIS) solar sells. Processing steps of interest include heating in a vacuum, exposure to selenium vapor at elevated temperatures, and deposition of CIS and CIGS layers over the Mo. Resulting Mo films and structures were subsequently characterized using XPS, SEM, Auger, and SIMS. Here, they describe the results of these experiments and their implications for CIS cell fabrication