【Device Papers】Self-powered ultraviolet photodetectors based on sub-100-nm nonstoichiometric β-Ga₂O₃−δ thin films: role of oxygen vacancies in carrier transport

      Researchers from the Chosun University have published a dissertation titled "Self-powered ultraviolet photodetectors based on sub-100-nm nonstoichiometric β-Ga₂O_3−δ thin films: role of oxygen vacancies in carrier transport" in Japanese Journal of Applied Physics.

Abstract

      We report on the performance of ultraviolet (UV) photodetectors based on nonstoichiometric β-Ga₂O_3−δ thin films with a thickness of 65 nm. The epitaxial Ga₂O_3−δ films were deposited on sapphire(0001) substrates by radio-frequency powder sputtering at 500 ℃. The oxygen-deficient, nonstoichiometric nature of the films was confirmed by hard X-ray photoelectron spectroscopy. The fabricated metal–semiconductor–metal photodetectors exhibited a photo-to-dark-current ratio of 2.17 × 10², photoresponsivity of 136.15 A/W, and specific detectivity of 5.06 × 10¹³ Jones at 10 V under 254 nm UV illumination. Self-powered operation was achieved, yielding a photocurrent of ~0.6 nA at a nominal zero bias. Biexponential fitting of the time-resolved response revealed slow decay components attributed to oxygen-vacancy-related traps. These results indicate that the oxygen vacancies play a dual role by enhancing the photocurrent through free-carrier generation and contributing to persistent photoconductivity. Our findings demonstrate promising potential of sub-100-nm nonstoichiometric β-Ga₂O_3−δ thin films for high-performance UV photodetectors.

DOI：https://doi.org/10.35848/1347-4065/adf7f1