Defect termination on crystalline silicon surfaces by hydrogen for improvement in the passivation quality of catalytic chemical vapor-deposited SiNx and SiNx/P catalytic-doped layers

摘要

We investigate the role of hydrogen (H) in the improvement in the passivation quality of silicon nitride (SiNx) prepared by catalytic chemical vapor deposition (Cat-CVD) and Cat-CVD SiNx/phosphorus (P) Cat-doped layers on crystalline silicon (c-Si) by annealing. Both structures show promising passivation capabilities for c-Si with extremely low surface recombination velocity (SRV) on n-type c-Si. Defect termination by H is evaluated on the basis of defect density (N-d) determined by electron spin resonance (ESR) spectroscopy and interface state density (D-it) calculated by the Terman method. The two parameters are found to be drastically decreased by annealing after SiNx deposition. The calculated average D-it at midgap (Dit-average) is 2.2 x 10(11) eV(-1)cm(-2) for the SiNx/P Cat-doped c-Si sample with a SRV of 2 cm/s, which is equivalent to 3.1 x 10(11) eV(-1)cm(-2) for the SiNx/c-Si sample with a SRV of 5 cm/s after annealing. The results indicate that H atoms play a critical role in the reduction in D-it for SiNx/c-Si and SiNx/P Cat-doped c-Si, resulting in a drastic reduction in SRV by annealing. (C) 2016 The Japan Society of Applied Physics