Minority Carrier Lifetime Enhancement of C-Si/TiO2 Heterojunction by Post Deposition Annealing

32nd European Photovoltaic Solar Energy Conference and Exhibition; 267-269
Titanium Oxide has recently been demonstrated as an electron selective layer because of its asymmetric band offsets with conduction and valence band of silicon [1]. In order to be used as an electron extracting layer in non P-N junction solar cells TiO2 thin films also need to passivate the silicon dangling bonds at the interface. In this work we report reduction of surface recombination velocity by TiO2 films deposited by Thermal Atomic Layer Deposition (T-ALD) and Plasma Atomic Layer Deposition (P-ALD). The as deposited sample with TiO2 deposited by thermal ALD showed an implied VOC of 568 mV and a high surface recombination velocity (SRV) of more than 5000 cm/s. The post annealing of this samples yielded a high implied VOC of 658 mV and surface recombination velocity of less than 120 cm/s.