Alpha particle detection based on a NiO/β-Ga₂O₃ heterojunction diode

Alpha particle detection has been achieved using a NiO/β-Ga₂O₃ heterojunction diode (HJD) detector, demonstrating the great potential of β-Ga₂O₃ devices for ionizing particle detection. Featuring a large area (700 × 700 μm²) and a low reverse leakage current (10⁻¹⁰ A), the HJD detector exhibited apparent energy spectra of ²³⁹Pu-generated alpha particles with an energy of 5.155 MeV at various bias voltages from −20 to −150 V. The peak energy of the energy spectra increased with the bias voltages. In contrast, the full width at half-maximum of the spectra was almost unchanged at high bias voltages, leading to an increased energy resolution with the increase in the bias voltages. The detector's charge collection efficiency (CCE) and energy resolution reached 14.82% and 17.54% at −150 V, respectively. The compromised CCE and energy resolution were revealed to be limited by the insufficient depletion width of the NiO/β-Ga₂O₃ HJD.