Ga 2 O 3 Field-Effect-Transistor-Based Solar-Blind Photodetector With Fast Response and High Photo-to-Dark Current Ratio

A high-performance solar-blind photodetector based on Cr-doped gallium oxide (Ga 2 O 3 ) has been fabricated. A 140-nm-thick Ga 2 O 3 layer was mechanically exfoliated from bulk crystal. The photodetector was based on a field-effect transistor structure, which showed a very high photo-to-dark current ratio larger than 10 6 and excellent current saturation. When the photodetector was tested with a 254-nm ultra-violet light, the ratio of drain current with and without the UV light reached nearly six orders of magnitude. The dark current was as low as 5 pA. Furthermore, the current rise time and decay time were both about 25 ms. High responsivity of ${4.79} \times {10}^{{5}}$ A/W and external quantum efficiency of ${2.34} \times {10}^{{6}}$ also have been achieved at the same time.