GaN-Based Metal–Insulator–Semiconductor Ultraviolet Photodetectors with CsF Current-Suppressing Layer

Abstract

GaN metal–insulator–semiconductor (MIS) ultraviolet (UV) photodetectors (PDs) with the CsF current-suppressing layer were, for the first time, fabricated and characterized successfully. It was found that we can achieve a low dark current and large photocurrent-to-dark-current contrast ratio from the proposed devices with the use of the CsF current-suppressing layer. With a 5 V applied bias, it was found that the leakage current of the fabricated MIS PDs with the CsF current-suppressing layer was 7.1×10-10 A. This small leakage current should be attributed to the large barrier height caused by the insertion of the CsF current-suppressing layer. With a 5 V applied bias, the barrier height of ΦB = 0.942 can be calculated from the dark current–voltage (I–V) characteristics. We can also achieve a large UV-to-visible rejection ratio from the PDs with the CsF current-suppressing layer.