Enhanced AlGaN/GaN ultraviolet phototransistor: Achieving single-pixel imaging and communication

The ideal combination of high sensitivity and fast response speed is crucial for advanced photodetectors. Herein, we present a normally-off, visible-blind ultraviolet (UV) AlGaN/GaN phototransistor featuring a fluorine-ion-implanted trench gate structure. This design effectively disrupts the conductive channel of the AlGaN/GaN heterostructure, drastically reducing the dark current to the magnitude of 0.1 pA. The trench structure enhances the localized electric field in the confined gate region, significantly improving UV detection sensitivity. Additionally, the finite electric field enhancement induced from fluorine ions (F− ions) accelerates the establishment of photogenerated electron channels. Consequently, the phototransistor exhibits ultrafast response speed, with rise and decay times of 1.5 and 6.7 μs, respectively, along with an exceptional specific detectivity of 3.45 × 1016 cm·Hz1/2 W−1. The detection of weak UV light reaches as low as 76.0 nW/cm2. This remarkable detection capability allows the device to perform high-fidelity single-pixel imaging and facilitates real-time UV communication. The proposed AlGaN/GaN phototransistor, characterized by a straightforward fabrication process and excellent photoresponse performance, presents enticing prospects for multiple performance compatible optoelectronic devices.