Abstract. We report on the investigation of effective SiO 2 passivated layer deposited at low temperatures. Comparison with the unpassivated photodiodes, at 77 K, the dark current density is reduced by one order of magnitude is achieved by introducing SiO 2 -passivated layer deposition technology at a lower temperature of 75 °C. The temperature-dependence and bias-dependence of the dark current are studied experimentally and correlated to the theory, and then the contribution of each dark current mechanism is also identified.