Effective passivation of Si surfaces by plasma deposited SiO x/a-SiNx:H stacks

Abstract

Very low surface recombination velocities <6 and <11 cm/s were obtained for SiOx/a-SiNx:H stacks synthesized by plasma-enhanced chemical vapor deposition on low resistivity n - and p -type c-Si, respectively. The stacks induced a constant effective lifetime under low illumination, comparable to Al2 O3 on p -type Si. Compared to single layer a -SiNx:H, a lower positive fixed charge density was revealed by second-harmonic generation measurements, while field-effect passivation was absent for a reference stack comprising thermally grown SiO 2. The results indicate that hydrogenation of interface states played a key role in the passivation and remained effective up to annealing temperatures >800°C. © 2011 American Institute of Physics.