GaN-Based Metal–Semiconductor–Metal Ultraviolet Photodetectors with the ZrO₂Insulating Layer

Abstract

GaN metal–semiconductor–metal (MSM) ultraviolet (UV) photodetectors (PDs) with ZrO 2 insulating layers were successfully fabricated and characterized. It was found that we can achieve a small dark current and large photocurrent to dark current contrast ratio from the proposed devices with the use of ZrO 2 insulating layers. With a 20 V applied bias, it was found that the leakage current of the fabricated MSM PDs with ZrO 2 insulating layers was 1.73 ×10 -10 A. This small leakage current should be attributed to the large barrier height caused by the insertion of the ZrO 2 insulating layers. We can also achieve a large UV to visible rejection ratio from the PDs with ZrO 2 insulating layers. Furthermore, it was also found that we can significantly reduce noise equivalent power and enhance detectivity by using ZrO 2 insulating layers.