β-Ga2O3 based solar-blind photodetectors have strong radiation hardness and great potential applications in Earth's space environment due to the large bandgap and high bond energy. In this work, we investigated the photoelectric properties influence of β-Ga2O3 photodetector irradiated by 100 MeV high-energy protons which are the primary components in the inner belt of the Van Allen radiation belts where solar-blind photodetectors mainly worked. After proton irradiation, due to the formation of more oxygen vacancies and their migration driven by bias at the metal/semiconductor interface, transportation of carriers transforms with electron tunneling conduction for low-resistance state and thermionic emission for high resistance state. As a result, the current–voltage curves of β-Ga2O3 solar-blind photodetectors exhibit apparent hysteresis loops. The photoresponsivity of β-Ga2O3 photodetectors slightly increases from 1.2 × 103 to 1.4 × 103 A/W after irradiation, and the photoresponse speed becomes faster at a negative voltage while slower at positive voltage. The results reveal the effects of high-energy proton irradiation on β-Ga2O3 solar-blind photodetectors and provide a basis for the study of their use in a radiation harsh environment.
Alloying with the divalent elements (such as Zn and Mg) in β-Ga2O3 thin film can reduce the dark current and improve the photorespond speed for the solar-blind ultraviolet (UV) photodetector. However, alloying only with one element will change the spectral sensitivity out of solar-blind area due to an increase of band gap for the Mg alloyed and a decrease for Zn alloyed. Herein, a unchange band gap in β-Ga2O3 thin films were obtained by Zn/Mg co-alloyed through radio frequency magnetron sputtering. The photodetector based on Zn/Mg co-alloyed β-Ga2O3 thin films shows a low dark current (6.2 × 10−12 A at 1 V), a high ratio of photo-to-dark current (1.8 × 104), a high responsivity of 25.7 mA W−1 (to 254 nm), a high rejection ratio (R
254 nm/R
280 nm) of 1.2 × 103 under the bias of 10 V, and a fast photoresponse time (less than 0.5 μs for the rise time), which can be practically used to detect weak solar-blind deep UV signals.
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