Self-powered DUV photodetector harvesting piezoelectric energy in a Ga₂O₃/ZnO nanorod heterojunction

This study demonstrates the fabrication of a self-powered deep-ultraviolet (DUV) photodetector (PD) based on Ga2O3/ZnO heterostructured piezoelectric nanogenerators (PENGs), optimized through controlled thermal annealing. ZnO nanorods were synthesized via hydrothermal growth, while Ga2O3 thin films were deposited by RF magnetron sputtering, followed by annealing at 400–600 °C to modulate interfacial properties. XRD and PL spectra highlighted optimal crystallinity at 600 °C, with a dominant (002) ZnO orientation and the lowest defect to near-band-edge (NBE) emission ratio (defect ratio ≈ 0.01). Electrical characterization under 254 nm DUV illumination showed a 60 % enhancement in output voltage and 62 % in output current for 600 °C-annealed devices compared to as-prepared samples. The optimized heterostructure achieved a peak voltage responsivity of 920 V·cm2/W at 254 nm ultraviolet C (UVC) band with a photo/dark rejection ratio of 103. These results validate the synergistic effect of Ga2O3/ZnO heterojunction engineering and thermal annealing in enabling high-sensitivity, self-powered DUV photodetection for UVC monitoring applications.