Demonstration of p-GaN/AlGaN/GaN-based ultraviolet phototransistors with sub-saturated transfer characteristics

Abstract

We report ultraviolet phototransistors (UVPTs) based on p-GaN/AlGaN/GaN high-electron-mobility transistors (HEMTs). Thanks to the effective depletion of the two-dimensional electron gas by the p-GaN layer, a dark current as low as 5.2×10-10 A/mm was achieved. Moreover, a unique sub-saturated region can be formed in the transfer curve of the UVPTs due to the special photogenerated electric field in the heterostructure, which endows the device with a large photo-to-dark current ratio over 105. In particular, responsivity up to 1.3×108 and 6.1×103 A/W was demonstrated at gate voltage of 5 and 0.68 V, respectively. The minimum rise time and fall time of the device transient response were measured to be around 1.8 ms and 8.8 ms, respectively. This work shows great UV detection potential of the p-GaN/AlGaN/GaN HEMTs, which opens up possibilities of realizing multifunctional enhancement HEMTs for future III-V photonic integrated devices and systems.

Highly Responsive Gate-Controlled p-GaN/AlGaN/GaN Ultraviolet Photodetectors with a High-Transmittance Indium Tin Oxide Gate

“…Gallium nitride (GaN), one of the most well-known wide-bandgap semiconductors, has already been widely applied in various fields such as illumination, power electronics, and communications [ 1 , 2 ]. Recently, GaN has received increased attention for ultraviolet photodetectors (UVPD) [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. At present, ultraviolet photodetectors are used in aerospace, sensors, flame detection, and other applications.…”