Unveiling Superior Solar-Blind Photodetection with a NiO/ZnGa₂O₄ Heterojunction Diode

This investigation presents a self-powered, solar-blind photodetector utilizing a low-temperature fabricated crystalline NiO/ZnGa₂O₄ heterojunction with a staggered type-II band alignment. The device leverages the pyrophototronic effect (PPE), combining the photoelectric effect in the p-n junction and the pyroelectric effect in the non-centrosymmetric ZnGa₂O₄ crystal. This synergistic effect enhances the photodetector's performance parameters, thereby outperforming traditional solar-blind photodetectors. The device demonstrates an extremely low dark current of 5.39 fA, a high responsivity of 88 mA/W, and a very high specific detectivity of 2.03 × 10¹⁴ Jones under 246 nm light irradiation at 0 V bias. Significantly, due to the PPE, the impact demonstrates a much-enhanced transient response when tested under various light intensities, ranging from 18 to 122 μW/cm². The photodetector shows a high responsivity of 338 A/W and an outstanding detectivity of 7.1 × 10¹⁸ Jones with an applied voltage of -13 V, showing its ability to detect weak signals. Single-crystalline ZnGa₂O₄ fabricated by MOCVD exhibits significant absorption of deep UV light, and the heterojunction's type-II band alignment with NiO is responsible for its exceptional self-powered pyrophotoelectric detecting and rectifying capabilities.