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

The surface passivation of low-temperature-deposited SiN_x films has been investigated in PIN type In_0.83Ga_0.17As photodiodes. In contrast to SiN_x films (330 °C) fabricated by PECVD (Plasma enhanced chemical vapor deposition), the low-temperature-deposited SiN_x films (75 °C) fabricated by ICPCVD (Inductively coupled plasma chemical vapor depositon) have a good effect on passivation of In_0.83Ga_0.17As photodiodes, which caused reductions of dark current as large as 2–3 orders of magnitude at the same test temperature 200 K. The effects of low-temperature-deposited SiN_x passivations with lowrate (∼16 nm/min) model were compared to the ones with highrate (∼100 nm/min) model. SiN_x films with lowrate model have a better effect on reducing dark current of the photodiodes. The different SiN_x films were studied by SIMS. The results show that the content of oxides in SiN_x layer fabricated by PECVD is 2 orders of magnitude more than that in SiN_x layer fabricated by ICPCVD which could be the reason that low-temperature-deposited SiN_x passivation leads to higher performance. Further, the dark current density of the photodiodes with lowrate-deposited SiN_x passivations does not show the dependence on the perimeter-to-area(P/A) of the junction.