RF Performance of Planar III–V Nanowire-Array Transistors Grown by Vapor–Liquid–Solid Epitaxy

The radio frequency (RF) performance of a III-V transistor comprised of nanowire (NW) high-electron mobility channels, grown by planar vapor-liquid-solid epitaxy in parallel arrays, is examined. An equivalent small-signal circuit model was used to study the contributing extrinsic and intrinsic passive elements on the NW performance as a function of bias and gate length (L_G). Adequate intrinsic gain (gm/gds) ~25 with low intrinsic (R_i) and terminal resistances (R_G, R_S, R_D) lead to an f_T/f max ~ 30/78 GHz for L_G = 150 nm and NW diameter ~160 nm. The gate capacitance (C_g) is extracted and ~2/3 of the total C_g is parasitic, which can be reduced with denser NW arrays. Excellent agreement between measured and modeled RF performance is achieved.