Atomic Layer Deposition of AlO _x /SnO _y Passiv

Post‐deposition treatment of AlO _x /SnO _y bilayer obtained by atomic layer deposition on FZ n‐type Si enhances the effective carrier lifetime beyond values realized with either material individually. The improved passivation is attributed to the 15 nm thick capping SnO _y layer, which effectively suppresses outward hydrogen effusion. Replacing the conventional emitter passivation layer in a Passivated Emitter Rear Contact (PERC) cell with this bilayer stack results in an absolute efficiency gain of 2.4% under rear illumination. Device simulations identify the probable mechanisms as improved rear surface passivation and rear‐side doping, both induced by the processing conditions of the bilayer. The PC1D simulations predict that processing‐induced rear side improvements coupled with the enhanced front side passivation should enable PERC‐based cells with bifacial power conversion efficiency exceeding 25%.