Dramatic reduction in dark current of β-Ga2O3 ultraviolet photodectors via β-(Al0.25Ga0.75)2O3 surface passivation

• Published in: Chinese physics B Vol. 32; no. 1; pp. 464 - 469
• Main Authors: Yue, Jian-Ying, Ji, Xue-Qiang, Li, Shan, Qi, Xiao-Hui, Li, Pei-Gang, Wu, Zhen-Ping, Tang, Wei-Hua
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and IOP Publishing Ltd 01.01.2023; Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China; State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China%State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China%Laboratory of Optoelectronics Materials and Devices, School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China; State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; College of Electronic and Optical Engineering&College of Microelectronics, National and Local Joint Engineering Laboratory for RF Integration and Micro-Packaging Technologies, Nanjing University of Posts and Telecommunications, Nanjing 210046, China
• Subjects: Al; defect passivation; Ga; MOCVD; photodetectors; photodetectors; β-(Al0.25Ga0.75)2O3/β-Ga2O3; MOCVD; defect passivation
• ISSN: 1674-1056
• DOI: 10.1088/1674-1056/ac8a8e

Solar-blind ultraviolet photodetectors with metal-semiconductor-metal structure were fabricated based on β-(Al0.25Ga0.75)2O3/β-Ga2O3 film grown by metal-organic chemical vapor deposition. It was known that various surface states increase dark current and a large number of defects can hinder the transport of carriers, resulting in low switching ratio and low responsivity of the device. In this work,β-(Al0.25Ga0.75)2O3 films are used as surface passivation materials. Owning to its wide band gap, we obtain excellent light transmission and high lattice matching withβ-Ga2O3. We ex-plore the change and mechanism of the detection performance of theβ-Ga2O3 detector afterβ-(Al0.25Ga0.75)2O3 surfacepassivation. It is found that under the illumination with 254 nm light at bias 5 V, theβ-(Al0.25Ga0.75)2O3/β-Ga2O3 pho-todetectors show dark current of just 18 pA and high current on/off ratio of 2.16 × 105. The dark current is sharply reduced about 50 times after passivation of theβ-Ga2O3 surface, and current on/off ratio increases by approximately 2 times. It isobvious thatβ-Ga2O3 detectors withβ-(Al0.25Ga0.75)2O3 surface passivation can offer superior detector performance.