High-Photoresponsivity Self-Powered <i>a</i>-, ε-, and β-Ga₂O₃/p-GaN Heterojunction UV Photodetectors with an <i>In Situ</i> GaON Layer by MOCVD

Abstract

In this paper, self-powered ultraviolet (UV) photodetectors with high response performance based on Ga₂O₃/p-GaN were fabricated by metal-organic chemical vapor deposition (MOCVD). The effects of different crystal phases of Ga₂O₃ (including <i>a</i>, ε, ε/β, and β) grown on p-GaN films on the performance of photodetectors were systematically studied. Moreover, an <i>in situ</i> GaON dielectric layer improved the responsivity of Ga₂O₃/p-GaN photodetectors by 20 times. All Ga₂O₃/p-GaN photodetectors showed self-power capability without bias. An ultralow dark current of 3.08 pA and a <i>I</i>_photo/<i>I</i>_dark ratio of 4.1 × 10³ (1.8 × 10³) under 254 nm (365 nm) light were obtained for the β-Ga₂O₃/p-GaN photodetector at 0 V bias. Furthermore, the β-Ga₂O₃/p-GaN photodetector showed excellent sensitivity with a high responsivity of 3.8 A/W (0.83 A/W), a fast response speed of 66/36 ms (36/73 ms), and a high detectivity of 1.12 × 10¹⁴ Jones (2.44 × 10¹³ Jones) under 254 nm (365 nm) light at 0 V bias. The carrier transport mechanism of the Ga₂O₃/p-GaN self-powered photodetector was also analyzed through the device energy band diagram. This work provides critical information for the design and fabrication of high-performance self-powered Ga₂O₃/p-GaN UV photodetectors, opening the door to a variety of photonic systems and applications without an external power supply.