Surface passivation of In0.83Ga0.17As photodiode with high-quality SiN layer fabricated by ICPCVD at the lower temperature

Abstract

The surface passivation of low-temperature-deposited SiNx films has been investigated in PIN type In0.83Ga0.17As photodiodes. In contrast to SiNx films (330°C) fabricated by PECVD (Plasma enhanced chemical vapor deposition), the low-temperature-deposited SiNx films (75°C) fabricated by ICPCVD (Inductively coupled plasma chemical vapor depositon) have a good effect on passivation of In0.83Ga0.17As photodiodes, which caused reductions of dark current as large as 2–3 orders of magnitude at the same test temperature 200K. The effects of low-temperature-deposited SiNx passivations with lowrate (∼16nm/min) model were compared to the ones with highrate (∼100nm/min) model. SiNx films with lowrate model have a better effect on reducing dark current of the photodiodes. The different SiNx films were studied by SIMS. The results show that the content of oxides in SiNx layer fabricated by PECVD is 2 orders of magnitude more than that in SiNx layer fabricated by ICPCVD which could be the reason that low-temperature-deposited SiNx passivation leads to higher performance. Further, the dark current density of the photodiodes with lowrate-deposited SiNx passivations does not show the dependence on the perimeter-to-area(P/A) of the junction.