75GHz Ga2O3/GaN Single Nanowire Metal- Oxide-Semiconductor Field-Effect Transistors

We reported high-speed transport properties on gallium nitride (GaN) single nanowire (NW) transistors laterally grown on the (0001) sapphire substrates. Due to the preservation of surface stoichiometry and passivation effects by the facet growth of [112̅0]Ga₂O₃/GaN, the 60nm-dia. SNW-MOSFET device of 0.2μm gate length was shown to exhibit a saturation current of 145μA, current on/off ratio of 10⁵, sub-threshold swing of 85mV/dec, transconductance of 74μS, and unity current/power gain cut-off frequency f_T/f_max of 75/96GHz. From a 3D diffusion and drift model analysis, these electric characteristics can be ascribed to a polarization induced 2D electron gas (2DEG) effect with a density of 7 x 10¹² cm^-2 confined at the semi-polar {11̅01̅} GaN/Ga₂O₃ interfaces. Immune to the post-growth processing induced damage and stress effects, our device performance can be characterized by a channel mobility of 1600cm²/V-sec which approaches the intrinsic mobility value of bulk GaN.