Passivation study of the amorphous crystalline silicon interface formed using DC saddle-field glow discharge

The DC saddle-field (DCSF) glow discharge method was used to deposit intrinsica-Si:H onto c-Si to passivate the c-Si surface. The effective minority carrier lifetime in the heterostructures as a function of the excess minority carrier density in the c-Si wafers was measured. The results were then analyzed in the context of recombination associated with interface defect states using three known recombination models. The defect density and the charge density at the interface are inferred. In addition subsequent annealing of the samples was studied. It is shown that for our intrinsic a-Si:H samples improvements in surface passivation are directly correlated with the reduction of interface defects and not the reduction of minority carrier concentration at the interface due to electric field. We have achieved excellent surface passivation with effective carrier lifetime >4ms for an intrinsic a-Si:H sample deposited at a process temperature of 200 degrees C and thickness of about 30nm. It is also demonstrated that subsequent annealing, at 240 degrees C, of the samples which were prepared at process temperatures <240 degrees C greatly increases the effective lifetime. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim