Fermi-Level Splitting-Induced Light-Intensity-Dependent Recombination in Fully Ultra-Wide Bandgap Deep-Ultraviolet Photodetector

Ga2O3-based heterojunction features the capability of self-driven detection, which is reckoned as a promising candidate for the next-generation deep-ultraviolet (DUV) sensing scenarios. Heterojunction consisting of fully ultra-wide bandgap (UWB) semiconductors would prevent additional response in the near-ultraviolet band. In this work, a
$\beta $
-Ga2O3/AlN heterojunction photodetector is constructed and its operating mechanisms are investigated. By measuring its static current-voltage (I-V) and dynamic current-time (I-t) characteristics, the detection performance, including a photo-to-dark current ratio of
$8.6\times 10\,\,^{\mathrm{ 5}}$
, a responsivity of 0.41 mA/W, a specific detectivity of
$3.4\times 10\,\,^{\mathrm{ 12}}$
Jones, and an external quantum efficiency of 0.2% were achieved under 0 V bias, indicating that the proposed device realized high-performance self-driven detection. Moreover, this work demonstrated the impact of Fermi-level splitting introduced by the enhanced photo illumination on the carrier recombination and the sensing performance. With the increase of light intensity, Fermi levels are separated and available recombination centers are increased, leading to the enhancement of the recombination process and the variation of detection properties. Consequently, this work highlights the potential of the fully UWB heterojunction and provides further optimization guidelines.