The 1/f noise characteristics of In0.83Ga0.17As photodiodes with SiNx passivation films fabricated by two different techniques

•ICPCVD passivation largely suppresses the 1/f noise of diode compared to PECVD.•The advantage of ICPCVD passivation is more conspicuous at the lower temperature.•The 1/f noise of diode passivated by PECVD mainly comes from perimeter.•The 1/f noise of diode passivated by ICPCVD mainly comes from bulk and upper surface.

The 1/f noise characteristics of In0.83Ga0.17As photodiodes have been studied in this work. The surface SiNx passivation films of photodiodes are fabricated by plasma enhanced chemical vapor deposition (PECVD) and inductively coupled plasma chemical vapor deposition (ICPCVD), respectively. The noise measurements are performed at variable reverse bias and temperature for different area diodes. The results show that ICPCVD passivation improves the surface quality and suppresses the 1/f noise significantly compared to PECVD passivation. The 1/f noise has an exponential relationship with reverse bias between 0.1 V and 0.5 V at room temperature for the diodes passivated by PECVD while it is a power law relationship for the diodes passivated by ICPCVD. As the temperature dropping, the 1/f noise of the diodes passivated by ICPCVD decreases more rapidly at reverse bias 0.1 V, which implies the advantage of ICPCVD passivation becomes more conspicuous at the lower temperature. According to the observed geometry dependence, the 1/f noise of the diodes passivated by PECVD dominantly originates from the perimeter, whereas it dominantly originates from the bulk and upper surface for the diodes passivated by ICPCVD.