High-responsivity β-Ga2O3/GaN heterojunction UV photodetectors with tunable multi-band detection capability†

The detection of ultraviolet (UV) radiation is of paramount importance, and has expanding applications in industrial, scientific, environmental, and biomedical fields. Using heterojunctions to fabricate UV photodetectors (PDs) is an effective approach for achieving multi-band detection. This study reports on high-responsivity β-Ga₂O₃/GaN heterojunction UV PDs, featuring tunable multi-band detection capabilities. The as-fabricated PDs demonstrate an exceptional photoresponsivity of 91.2 mA W⁻¹ under 250 nm illumination at zero bias. Furthermore, the spectral response of the Ga₂O₃/GaN heterojunction PDs can be precisely modulated by varying the applied bias voltage, facilitating distinct UVC-dominated and broadband UVA/UVC detection modes with enhanced detectivity. The underlying mechanism responsible for the tunable spectral responses is elucidated. This research not only introduces a straightforward and practical approach for developing multi-band UV PDs regulated by bias voltage, but also provides a comprehensive understanding of the physical mechanisms driving the photoelectric response. These advancements address the increasing demand for UV PDs, and provide guidance for the optimization of device performance and the discussion of intrinsic physical mechanisms in this field.