Photoelectric properties and persistent photoconductivity of GaN-based ultraviolet photodetectors

Abstract

Persistent photoconductivity deeply affects the performance of the photodetector, and has been studied in a variety of semiconductor optoelectronic devices. In this work, AlGaN/GaN metal-heterojunction-metal (MHM) ultraviolet (UV) detectors and GaN metal-semiconductor-metal (MSM) ultraviolet detectors were prepared using transverse Schottky contacts, and characterized at different temperatures, light intensity and bias voltage. The two-dimensional electron gas (2-DEG) at the Schottky heterojunction of AlGaN and GaN is used to generate high-speed electron mobility, which significantly improves the response speed and responsivity of photogenerated carriers. Under the illumination of 365 nm center ultraviolet light with an intensity of 4.4 mW/cm2, the photocurrent can reach 434 μA-MHM and 38 μA-MSM (25 °C), and the attenuation rate increase by 2.8 times, 5 times and 3.7 times with temperature (25 °C-250 °C), bias voltage (5/10/15 V), and light intensity (0.33/1.1/4.4 mW/cm2), respectively, and the attenuation rate reaches 50∼80 times.