Metal-Semiconductor-Metal ε-Ga2O3 Solar-Blind Photodetectors with a Record High Responsivity Rejection Ratio and Their Gain Mechanism

In recent years, Ga2O3 solar-blind photodetector (SBPD) has been attached great attention for its potential application in solar-blind imaging, deep space exploration, and confidential space communication, etc. In this work, we demonstrated an ultrahigh performance e-Ga2O3 metal-semiconductor-metal (MSM) SBPD. The fabricated photodetectors exhibited record-high responsivity and fast decay time of 230 A/W and 24 ms, respectively, compared with MSM-structured Ga2O3 photodetectors reported to date. Additionally, the e-Ga2O3 MSM SBPD presents ultrahigh detectivity of 1.2×1015 Jones with low dark current of 23.5 pA under the operation voltage of 6 V, suggesting its strong capability of detecting an ultraweak signal. The high sensitivity and wavelength selectivity of the photodetector were further confirmed by the record high responsivity rejection ratio (R250nm/R400nm) of 1.2×105. From the temperature-dependent electrical characteristics in the dark, the thermionic field emission and Poole-Frenkel emission wer...