Effect of atomic hydrogen treatment on passivation quality of aluminum oxide for p-type crystalline silicon

We investigated effects of annealing and atomic hydrogen treatment on passivation quality of aluminum oxide (a-Al_1-xO_x:H) films deposited by plasma-enhanced chemical vapor deposition (PECVD) for p-type crystalline silicon (c-Si). We found that the surface recombination velocity (S_eff) decreased from 5.0 ×10² to 2.0 ×10¹ cm/s after 475°C annealing, however the S_eff increased up to 2.8×10³ cm/s after atomic hydrogen treatment. This change in the passivation quality was caused by the change in the negative fixed charge density. The negative fixed charge density increased from 1.2×10¹² to 2.9×10¹² cm^-2 by thermal annealing and decreased down to 5.9×10¹¹ cm^-2 by atomic hydrogen treatment. This result suggests that hydrogen at the a-Al_1-xO_x:H/c-Si interface significantly influences negative fixed charge density.