High Responsivity and Low Dark Current Ultraviolet Photodetectors Using p-GaN/AlGaN/GaN Heterostructure

This paper reports a p-GaN/AlGaN/GaN heterostructure photodetector (PD) with high responsivity and high photo-to-dark current ratio (Iph/Idark). Due to the inherent depletion of the 2-D electron gas in the heterostructure by the p-type GaN, the dark current of the PD is significantly suppressed without compromising the advantages of high photocurrent and responsivity in AlGaN/GaN heterostructure PDs. As a result, both a large responsivity of 2×10
⁴
A/W and a high Iph/Idark of 10
⁷
at a bias of 5 V were achieved in our device under UV light with a wavelength of 365 nm and intensity of 5 μW/mm
²
. Moreover, a large UV to visible rejection ratio of around 3000 was also observed in the device. The superior device performance in our work compared to other reported results suggests the great potential using the p-GaN/AlGaN/GaN heterostructure based PDs for high-sensitivity UV detection.