Light-induced degradation of native silicon oxide-silicon nitride bilayer passivated silicon

This article reports on the effects of aging and light induced degradation of the passivation quality of the interface formed by the crystalline silicon surface and facile grown oxide-SiNx bilayer. Stable passivation quality against aging and light soaking require thicker oxide layers grown at room temperature, suggesting that thicker oxide layers mitigate the migration of hydrogen from the interface and hence the defect density under light soaking. In addition, the stoichiometry of the PECVD SiNx influences the stability of the passivation quality. Specifically, the rate of degradation in passivation quality is observed to correlate with the optical absorption properties of SiNx; the higher the optical absorption the greater the degradation in passivation. This result is attributed to neutralization of the K+ centers in SiNx. Passivation layers with SiNx deposited with 5% silane in nitrogen to ammonia gas ratio of 7 and facile grown native oxide thickness of similar to 1 nm resulted in the most stable passivation scheme within the scope of the reported experiments. (C) 2015 AIP Publishing LLC.