Phosphorus-doped polycrystalline silicon passivating contacts via spin-on doping

Polycrystalline silicon (poly-Si) passivating contacts are promising technologies to promote the efficiency of silicon solar cells, due to their low carrier recombination and low contact resistivity. In this work, we present phosphorus spin-on doping as an alternative doping method to fabricate high performance poly-Si passivating contacts. The influences of thermal treatments and intrinsic amorphous Si thickness on poly-Si passivating contact quality were investigated. A high implied open-circuit voltage of above 730 mV together with a low contact resistivity below 4 mΩ⋅cm² were obtained for 100 – 230 nm thick poly-Si layers after a thermal treatment at 975 °C for 60 min followed by a forming gas annealing. The promising results presented in this work imply that phosphorus spin-on doping can be an effective doping method alternative to conventional POCl₃ diffusion.