【Domestic Papers】 University of Science and Technology of China --- Crystal-phase engineering of ε-Ga₂O₃ for high-performance deep UV photodetectors via MOCVD

      Researchers from the University of Science and Technology of China have published a dissertation titled "Crystal-phase engineering of ε-Ga₂O₃ for high-performance deep UV photodetectors via MOCVD" in Science China Materials.

Acknowledgement

      This work was supported by the National Key Research and Development Program of China (2023YFB3610200 and 2024YFA1208800), the National Natural Science Foundation of China (61925110, U20A20207, 62304215, and 62171426), the University of Science and Technology of China (WK2100000025, YD2100002009, YD2100002010, and YD2100002007), the China Postdoctoral Science Foundation (2023M733367), and the CAS Project for Young Scientists in Basic Research (YSBR-029). This work was partially carried out at the Center for Micro and Nanoscale Research and Fabrication of the University of Science and Technology of China.

Abstract

      Gallium oxide (Ga₂O₃), with an ultrawide bandgap corresponding to the deep ultraviolet (DUV) spectra range, provides a potential subversive scheme for the filter-free DUV photodetection. Meanwhile, the various crystal phases of Ga₂O₃ provide more substrate options for achieving heteroepitaxy, with the coupling of Ga₂O₃ to SiC substrates conducive to developing integrated Ga₂O₃ DUV photodetectors. Phase engineering of β-Ga₂O₃ and ε-Ga₂O₃ was achieved on the commercial 4H-SiC substrate via metal-organic chemical vapor deposition. According to the in-depth analysis of different Ga₂O₃ growth stages, it was found that β-Ga₂O₃ is easy to form under high-pressure growth conditions, while low-pressure conditions promote the formation of ε-Ga₂O₃ at 500°C. Furthermore, the developed ε-phase dominated Ga₂O₃ DUV photodetector exhibits obvious advantages in high responsivity (∼639 A/W), photo-to-dark current ratio (∼2.4×10⁷), external quantum efficiency (∼3.15×10⁵%), and specific detectivity (∼9.62×10¹³ Jones) under 254 nm illumination. This work not only reveals the growth mechanism of Ga₂O₃ films under various pressures but also ensures the great potential of ε-Ga₂O₃ for highly sensitive DUV detection on the heterogeneous substrate, which is expected to expand the application of Ga₂O₃ optoelectronic devices.