High-Quality Doped Polycrystalline Silicon Using Low-Pressure Chemical Vapor Deposition (LPCVD)

In this work, analysis of n+ and p+ doped polycrystalline silicon (poly-Si) layers over in-situ grown interfacial silicon oxide (iOx) for use in passivated contact solar cells is presented. Both the poly-Si and the iOx are deposited using an industrial low-pressure chemical vapor deposition (LPCVD) tube furnace. The layers are deposited on planar Czochralski-grown silicon (Cz-Si) wafers and are analyzed for their thickness, in as-deposited and doped conditions. Outstanding surface passivation is demonstrated after n+ and p+ doping with appropriate capping layer after undergoing high-temperature firing. τeff as high as 15 ms (n+ poly-Si) and 3.1 ms (p+ poly-Si) at an excess carrier density of 1x1015 cm-3 are obtained. The iVoc values (at 1 sun) are in the range of 745 mV (n+ poly-Si) and 730 mV (p+ poly-Si) and ultra-low J0 values of 1.4 fA/cm2 (n+ poly-Si) and 7 fA/cm2 (p+ poly-Si) are obtained.