Thickness Effect on Operational Modes of ZnGa2O4 MOSFETs

Abstract

The device mechanism from depletion to enhancement mode for ZnGa2O4 metal-oxide semiconductor field effect transistors (MOSFETs) grown on the sapphire substrate by metalorganic chemical-vapor deposition was studied. It was found that the thickness of the ZnGa2O4 thin-film would affect the operational mode of the MOSFETs. Under the low-voltage operation (V-DS = 0.5 V), the transistors exhibited a high on/off ratio from 10(7) to 10(4), low subthreshold swing from 150 to 330 mV/dec, high field-effect mobility from 4.2 to 0.054 cm(2)/V-s and threshold voltages from - 17.8 to 4.1 V (using constant current = 1 nA). These electrical properties all depend on the thickness of the ZnGa2O4 thin-film transistors. Finally, the e-mode ZnGa2O4 thin-film transistor with off-state breakdown voltage over 400 V is fabricated.