Ultra-thin poly-Si/SiOx passivating contacts integration for high efficiency solar cells on n-type cast mono silicon wafers

In this work, ultra-thin (15nm) poly-crystalline Silicon (poly-Si) on silicon oxide (SiOx) stacks are elaborated on n-type cast-mono crystalline silicon (c-Si) wafers. Such advanced passivating contacts are integrated, in combination with TCO (Transparent Conductive Oxide) layers, on both front and rear sides of high efficiency solar cells via a simplified fabrication process. We showed that both Phosphorus (P) and boron (B) doped poly-Si layers provide an efficient external gettering effect on cast-mono wafers, leading to large improvements of bulk carrier lifetime. The first cell integration demonstrates best photovoltaic (PV) conversion efficiencies approaching 22% on cast-mono wafers. These results are therefore encouraging regarding the compatibility of low cost and low carbon footprint Si substrates with high efficiency passivated contacts cell structures.