Enhancement-Mode β-Ga2O3 Metal-Oxide-Semiconductor Field-Effect Solar-Blind Phototransistor With Ultrahigh Detectivity and Photo-to-Dark Current Ratio

An enhancement-mode beta-Ga2O3 metal-oxide-semiconductor field-effect solar-blind phototransistor on Si-doped homoepitaxial film grown by molecular beam epitaxy is demonstrated in this letter. Gate-recess process was employed to fully deplete the Ga2O3 channel to achieve positive threshold voltage V-th (7 V), which broadens the operating range of the solar-blind phototransistor. The dark current of about 0.7 pA is extremely low. Under 254-nm light illumination of 63 mu W/cm(2), the change of drain current reaches more than 6 orders of magnitude. Record high detectivity of 1.3 x 10(16) Jones and photo-to-dark current ratio of 1.1 x 10(6) are obtained, respectively. In addition, the rise and decay time are as short as 100 and 30 ms, respectively. High responsivity of 3 x 10(3) A/W and external quantum efficiency of 1.5 x 10(6)% are also achieved with apparent solar-blind photodetection.