Low voltage operation of GaN vertical nanowire MOSFET

GaN gate-all-around (GAA) vertical nanowire MOSFET (VNWMOSFET) with channel length of 300 nm and diameter of 120 nm, the narrowest GaN-based vertical nanowire transistor ever achieved from the top-down approach, was fabricated by utilizing anisotropic side-wall wet etching in TMAH solution and photoresist etch-back process. The VNWMOSFET exhibited output characteristics with very low saturation drain voltage of less than 0.5 V, which is hardly observed from the wide bandgap-based devices. Simulation results indicated that the narrow diameter of the VNWMOSFET with relatively short channel length is responsible for the low voltage operation. The VNWMOSFET also demonstrated normally-off mode with threshold voltage (V_TH) of 0.7 V, extremely low leakage current of ∼10⁻¹⁴ A, low drain-induced barrier lowering (DIBL) of 125 mV/V, and subthreshold swing (SS) of 66–122 mV/decade. The GaN GAA VNWMOSFET with narrow channel diameter investigated in this work would be promising for new low voltage logic application.