Double-Side Integration Of High Temperature Passivated Contacts: Application To Cast-Mono Si

We report in this paper on the development of thin passivating poly-crystalline Silicon (poly-Si) on silicon oxide (SiOx) stacks, with poly-Si films deposited by Low Pressure Chemical Vapor Deposition (LPCVD) and doped by Plasma Immersion Ion Implantation (PIII). Such advanced passivating contacts can be integrated, in combination with In-free TCO layers, at both the front and rear sides of high efficiency solar cells via simple fabrication processes. High iV(oc) values close to 700 mV were obtained just after the annealing step required for the poly-Si crystallization and dopant activation. The first cell integration demonstrated photovoltaic (PV) conversion efficiencies of 21.2% for this approach. Moreover, we demonstrated that the poly-Si layers elaboration process provides efficient external gettering effects on cast-mono wafers, with bulk carrier lifetime exceeding 3 ms after the poly-Si (n(+))/SiOx stack formation. These results are therefore encouraging for the use of low cost, low carbon footprint Si materials, in double-side passivated contacts high efficiency cell structures.