Monolithically Integrated UV Photodetector Based on p-NiO/GaN HEMTs

In this work, a high-performance ultraviolet (UV) photodetector (PD) based on p-NiO/AlGaN/GaN structure is proposed for optical switching or UV detection. With its good photosensitivity, a high photocurrent of 39.75 mA/mm is achieved with UV illumination. Moreover, due to the depletion of the two-dimensional electron gas by the p-NiO layer, the dark current is reduced to 5.85 × 10^-6 mA/mm. Hence, a high photo-to-dark current ratio of 6.79 × 10⁶ is achieved in this work. Furthermore, the voltage output signal is generated through monolithically integrated two-dimensional electron gas resistors, achieving a rise time τ_rise of 0.86 ms and a fall time τ_fall of 1.33 ms, respectively. This output can be directly interfaced with logic circuits without requiring an additional conversion circuit. The monolithic integration design reduces parasitic effects, thereby enhancing operating frequency. These results indicate the suitability of the proposed GaN PDs for high-sensitivity UV detection.