Analysis of p/n junction profiles by electron beam induced current towards high efficiency thin-film poly-Si solar cells

P/n junction profiles of thin film polycrystalline silicon (poly-Si) solar cells were directly observed by cross sectional electron beam induced current. The p/n junctions were formed by phosphorus diffusion process at 850-900/spl deg/C or n-type microcrystalline silicon (/spl mu/c-Si:H) deposition at 200/spl deg/C. The p/n junctions perpendicular to the substrate were observed for phosphorus diffusion process at 900/spl deg/C, while parallel p/n junction to the poly-Si film surface was formed for /spl mu/c-Si:H deposition. These results clearly suggested that preferential diffusion of phosphorus atoms along grain boundaries occurred for high temperature phosphorus diffusion process. We discussed the relationship between p/n junction profiles and solar cell performances.