Nonuniform Charge Collection In Siox-Based Passivated-Contact Silicon Solar Cells

In this contribution, we report on the charge-collection characteristics of silicon photovoltaic devices using passivated contacts based on the c-Si/SiOx/poly-Si structure. Using electron-beam induced current (EBIC) imaging in plan-view and cross-section orientations, we find that charge collection in a device with a 1.5-nm-thick SiOx layer is fairly uniform in the p-n junction region and does not appear to be influenced by pyramidal surface texture. In contrast, a device with a 2.2-nm-thick oxide layer shows significant spatial variation in the charge-collection signal. The apexes of the pyramids exhibit reduced EBIC signal whereas the valleys between adjacent pyramids show the strongest collection. Our results indicate that charge collection in c-Si/SiOx/poly-Si structures can be influenced by both the properties of the SiOx layer and surface texture.