Improvement of the conductivity and surface passivation properties of boron-doped poly-silicon on oxide

Passivating contacts of crystalline silicon (c-Si) solar cells with a poly-silicon layer (poly-Si) on a thin silicon oxide (SiOx) film offer an interesting approach to decrease the recombination current at the metal/c-Si interface and to increase the cell efficiency. This study focuses on the development of boron-doped poly-Si layers deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD) on top of a thin silicon oxide film. First, the deposition and annealing conditions were optimised in order to: (1) reduce the blistering of the poly-Si on the thin SiOx film and (2) improve the poly-Si conductivity. The passivation properties of the resulting structures have been shown to depend on the blister density and have been improved through a hydrogenation step leading to a maximum implied open-circuit voltage value of 721 mV.