Power Saving High Performance Deep-Ultraviolet Phototransistors Made of ZnGa₂O₄ Epilayers

Single-crystalline ZnGa2O4 epilayers with different diethylzinc (DEZn) flow rates were successfully grown on sapphire substrates. By decreasing the DEZn flow rate and keeping the deposition time constant, the operational mode of the transistors changed from depletion mode (D-mode) to enhancement mode (E-mode). The relevant electrical properties and physical characteristics are well presented and verified. An E-mode (DEZn = 10 sccm) n-channel thin-film transistor was fabricated for deep-ultraviolet (DUV) phototransistor application. In the phototransistor, the photocurrent gain values increased substantially in the DUV region, the peak value of which measures 1.54 × 102 at 240 nm. The superior performance of DUV phototransistors is correlated to the improvement in the quality of materials.