In Situ Growth of Al2O3 as a Passivation and Antireflection Layer on TiO2-Based MSM Photodetectors

Abstract

The in situ growth of Al2O3 on TiO2 by ultrasonic spray pyrolysis deposition is presented in this paper. Here, Al2O3 is used as the passivation and the antireflection layer. TiO2-based photodetectors (PDs) with Al2O3, SiO2, and no passivation layers were studied. It was found that the PD without the passivation layer has the highest dark current and photocurrent due to high internal photoconductive gain related to the reaction between the oxygen molecule and TiO2. The PDs with Al2O3 and SiO2 passivation layers suppress the internal photoconductive gain and show stable $I$ – $V$ characteristics after the PDs are exposed to air for 30 days. The device with the Al2O3 passivation layer showed the most stable $I$ – $V$ characteristics and the highest detectivity and the shortest response time among the three devices.