High-Performance p-GaN/AlGaN/GaN HEMT-Based Ultraviolet Phototransistors With fW-Level Weak Light Detection Capacity

this work, high-performance ultraviolet (UV) phototransistors (PTs) based on the p-GaN/ AlGaN/GaN HEMT structure were reported. An innovative strategy making a tradeoff between the absorption thickness of the incident light and the retraction distance of the depletion region was developed for the first time. The optimal PTs exhibited a large photo-to-dark-current ratio (PDCR) of 1.30 x 10(11), a high responsivity of 5.50 x 10(5 )A/W, and a record-high UV-to-visible rejection ratio (UVRR) over 1 x 10(9) while maintaining a fast response time of 136.0 mu s. Moreover, the devices present excellent weak light detection capability with a threshold light intensity as low as 7.90 nW/cm2, enabling direct detection of the 119.05 fW signal. Additionally, the measurement of the noise characteristics revealed that the low-frequency noise of the device originating from the trap dominated 1/f flicker noise, and a superior detectivity (D & lowast;) above 1 x 10(18) cm<middle dot>Hz1/2/W was achieved. The results suggest the enormous potential of p-GaN-based UV PTs for high- sensitivity visible-blind UV detection.