Abstract: In this work, β-Ga₂O₃ based metal-semiconductor-metal (MSM) solar-blind ultraviolet photodetector was successfully fabricated. At room temperature and a bias voltage of 5 V, the responsivity of the device with high-quality epitaxy is 469.6 mA/W (corresponding to an external quantum efficiency (EQE) of 229.2%), and the photocurrent-dark current ratio is 5.26×10³. In order to study the potential application of the β-Ga₂O₃ based MSM type solar-blind ultraviolet detector in high temperature environment, the current-voltage (I-V) and photoresponse (I-T) characteristic of the device at high temperature were tested, and the carrier transport mechanism of the device at high temperature was analyzed. The results indicate that the dark current of the device is mainly dominated by thermionic-field emission (TFE) at low voltage and Poole-Frenkel emission (PFE) at high voltage between 300 and 375 K. The I-V curve fitted by the PFE model shows that PFE is caused by defects near 0.200 eV below the conduction band. According to the fitting results of the photoresponse characteristic, the activation energy fitted by the decay time is 0.280 eV, and activation energy fitted by the rise time is 0.036 eV. According to the analysis results, the transport process of photocurrent is as follows: photogenerated electrons are first captured by defect energy levels near 0.200 eV to 0.280 eV below the conduction band and emitted into the conduction band through PFE to generate photocurrent; the recombination process of photogenerated charge carriers is that photoelectrons tend to be captured by defect energy levels near 0.036 eV below the conduction band, and then recombine with photogenerated holes in the valence band.

Key words: β-Ga₂O₃, metal-semiconductor-metal, solar-blind ultraviolet photodetector, thermionic-field emission, Poole-Frenkel emission, defect