Fabrication of AlGaN/GaN MISHEMT with dual-metal gate electrode and its performances

In this study, we investigated AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MISHEMTs) with single-metal gate (SMG) and dual-metal gate (DMG) structures through experimental measurements and technology computer-aided design simulation. The DMG structure consists of nickel (Ni) in the source-side gate and titanium (Ti) in the drain-side gate metals for the distribution of an electric field. The measurement results demonstrate that the fabricated AlGaN/GaN DMG–MISHEMT produces improved device performances; this includes higher drain current (I_D), higher transconductance (g_m), and higher breakdown voltage than the SMG–MISHEMT. The improvement is due to the distribution of an electric field. In addition, in terms of current collapse characteristics, the DMG–MISHEMT exhibited a small change rate in I_D at various quiescent bias points. These results mean that a DMG structure leads to excellent electrical characteristics.