High-Performance Ultraviolet Photodetector Arrays Based on Recessed-Gate HEMT with a Buried p-GaN Layer

Abstract

GaN, due to its large band gap and high carrier mobility, has been widely used in fast-response ultraviolet (UV) photodetectors (PDs). The existing junction-based and two-dimensional electron gas (2DEG)-based devices have different focuses on the performance of ultraviolet detection. To achieve comprehensive performance, we fabricate a high-performance UVPD utilizing a GaN recessed-gate high electron mobility transistor (HEMT) integrated with a p-GaN buried layer. Benefiting from the effective p-GaN/u-GaN depletion junction, the device has a low dark current of 1.75 × 10 –9 A at a voltage bias ( V ds ) of 2 V. Under 365 nm illumination, the recovery of 2DEG is obtained and results in an ultrahigh photocurrent exceeding 1 mA at V ds = 2 V. As a result, a maximum responsivity ( R ) of 532 A/W, an external quantum efficiency of 1.81 × 10 5 %, and a specific detectivity ( D *) of 1.09 × 10 14 Jones are attained at a light power density ( P ) of 0.24 mW cm –2 . Moreover, the influence of oxygen plasma treatment on the gate recess is explored. The response time is shortened from 1.07/1.20 to 0.79/1.05 ms, and the maximum I light / I dark ratio is increased by more than 10 times. Such high performance substantiates that the structure of GaN recessed-gate HEMT with p-GaN buried layer architecture holds great promise for the creation of an outstanding UV photodetector.