Hybrid GaO/AlGaN/GaN Ultraviolet Detector With Gate Metal in the Grooved AlGaN Layer for Obtaining Low Dark Current and Large Detectivity

In this work, a metal/Ga2O3/AlGaN/GaN hybrid-structured metal–semiconductor–metal ultraviolet photodetector (MSM UV PD) with low dark current has been proposed and fabricated. In the dark condition, the depletion region formed by the metal gate and the AlGaN layer pinches off the two-dimensional electron gas (2DEG) channel, and we can obtain a dark current even lower than 10−10 A/cm2. In the illumination condition, due to the electric field formed by the metal and the Ga2O3 layer, the photogenerated electrons will move to the AlGaN/GaN channel to form the 2DEG. We then get a photo-to-dark current ratio of $8.77\times10$ 8. Furthermore, the detectivity of the device is higher than $3.30\times10$ 12 Jones when a 254-nm UV illumination signal is applied.