Quadruple Gate-Recessed AlGaN/GaN Fin-Nanochannel Array Metal-Oxide-Semiconductor High-Electron Mobility Transistors

In this article, to study the features of the quadruple gate and quadruple T-gate structures in AlGaN/ GaN fin-nanochannel array metal-oxide-semiconductor high-electron-mobility transistors (MOSHEMTs), an ELS-7500 electron-beam lithography system was used to pattern the 80-nm-wide fin-nanochannel array, and the quadruple gate and quadruple T-gate structures. Compared with the conventional single-gate structure, the saturation drain-source current was improved from 1153 to 1958 mA/mm and 2009 mA/mm by using the quadruple gate structure and quadruple T-gate structure, respectively. Furthermore, the maximum extrinsic transconductance was also improved from 265 to 323 mS/mm and 340 mS/mm, respectively. Compared with the unit gain cutoff frequency (fT) of 7.7 GHz and the maximum oscillation frequency (fmax) of 15.1 GHz of the conventional single gate, the fT = 12.0 GHz and fmax = 18.6 GHz were obtained by using the quadruple gate structure. If the quadruple T-gate structure was utilized, the fT and fmax were further improved to 14.8 and 29.5 GHz. By simulating the equivalent circuits, the improved mechanisms were attributed to the enhancement of transconductance and the reduction of parasitic gate resistance and parasitic gate capacitance.