Temperature-dependent photodetection behavior of AlGaN/GaN-based ultraviolet phototransistors

Abstract

In this work, we investigated the temperature-dependent photodetection behavior of a high-performance AlGaN/GaN-based ultraviolet phototransistor (UVPT) operating under 265 nm illumination. As the temperature continuously rises from room temperature to 250 °C, the photocurrent of a device increases in the beginning but suffers from degradation afterwards. This can be explained by the competing process between the generation and recombination rate of photo-induced carriers in the UVPT at room and high temperatures. Intriguingly, we found that the optimal operating temperature for our UVPT is around 50 °C, featuring a high peak responsivity of 1.52 × 105 A/W under a light intensity of 45 μW/cm2. Furthermore, the photoresponse time of our UVPT is also highly temperature-dependent, exhibiting the shortest rise time of 50 ms at 100 °C while the decay time is monotonically reduced as the temperature rises to 250 °C. Notably, our AlGaN/GaN-based UVPTs exhibit ultra-high responsivity at high temperatures, which have outperformed those earlier reported UV photodetectors in the form of different device architectures, highlighting the great potential of such device configurations for harsh environment applications.