Pulsed X-Ray Detector Based on Vertical p-NiO/β-Ga₂O₃ Heterojunction Diode

Gallium Oxide (Ga₂O₃) devices have shown great potential for radiation detection. However, developing Ga₂O₃ detectors for pulsed radiation monitoring is still challenging, which requires high response sensitivity (R), low noise, high time resolution, and linear outputs. Herein, a vertical p-NiO/β-Ga₂O₃ heterojunction diode (HJD) is fabricated and its performance in X-ray detection is analyzed. Benefiting from the high quality of the p-n heterojunction, the HJD exhibits a low-leakage current density of less than 1.73 × 10⁻⁷ A cm⁻² at 100 V and features a high R of 7.92 μC Gy⁻¹ cm⁻², a low noise equivalent dose rate of 9.14 × 10⁻¹² Gy⁻¹ Hz^−0.5 at an X-ray dose rate of 0.383 Gy s⁻¹, and good linear outputs to X-ray dose rates from 0.0383 to 1.149 Gy s⁻¹. The conductive process of the HJD detector is dominated by the tunneling mechanism, which leads to a longer response time associated with the trapping and releasing process of the deep-level traps under the continuous X-ray illumination. However, the pulsed X-ray response property shows no significant influence from the slow trapping/releasing process of the traps. As a result, pulsed X-ray radiation detection with a 50 ns full width is achieved, and the time resolution of the detector is characterized to be 3.31 ns by a 20 ps laser source.