Studying the Effect of Type of Surface Passivation Layer on Performance Parameters of AlGaN MSM Detector

In past studies, it is reported that surface passivation helps to minimize surface leakage current in case of photodetectors. However, utilization of stack of passivation layers for Metal–Semiconductor–Metal (MSM) type detectors is studied in very few reports. In present study, we have investigated the effect of single passivation and stack of passivation layers on the performance parameters of AlGaN MSM detector as GaN or AlGaN layer exhibits higher surface state density, for three types of passivation layers and without passivation case also. Passivation layers like SiO2, Al2O3, and Al2O3/SiO2 (stack) have been utilized for investigation analysis. The comparison of performance parameters of passivated detectors and without passivation-based detector has been performed so that suitable selection of passivation can be done for enhanced performance. The considered performance parameters of detector are dark current density, electric field, recombination rate, and photocurrent-to-dark current density ratio. Comparison analysis shows that detector with Al2O3/SiO2 passivation stack provides lowest dark current density of 5e−08 A/cm2 at top surface of AlGaN layer as compared to other three types of detectors. Moreover, highest electric field, highest photocurrent-to-dark current density ratio, and lower recombination rate have been obtained with Al2O3/SiO2 passivated stack-based detector. Present work helps to select the type of passivation for AlGaN MSM detector so as to provide improved performance parameters and reliable UV detection for low noise applications.