Study on Optoelectronic Characteristics of ZnGa2O4 Thin-Film Phototransistors

Deep ultraviolet (DUV) phototransistors with high photoresponsivity are fabricated on ZnGa2O4 grown by metal-organic chemical-vapor deposition. Owing to transistor actions, the photodetector meets to a large photocurrent and optical response. When illuminated with photon wavelength within the range of 200-250 nm, the ZnGa2O4-based phototransistor presented a large responsivity, especially 1.51 X 10(6) A/W as the incident light at 210 nm with 1.73 mu W/cm(2). It was also observed that the photocurrent/dark current ratio and rising time can be improved by gate control, which is related to threshold voltage shifting when under illumination. These results demonstrate ZnGa2O4 based phototransistor is a very promising candidate for DUV optoelectronic devices applications.