Investigations on SiN-Passivated Γ-Gate Al[sub 0.27]Ga[sub 0.73]N∕GaN High Electron Mobility Transistors

SiN-passivated Γ-gate high electron mobility transistors with different SiN layer thicknesses (15, 30, and ) have been comprehensively investigated over a wide temperature range of . By using the shifted exposure method, the effective reduction in gate length, the SiN surface passivation, and the formation of a long field plate upon the gate–drain region are achieved at the same time. The present Γ-gate devices demonstrate improved device gain, current drive capability, wide temperature range linearity, and superior thermal threshold stability characteristics compared to a conventional device fabricated by using the identical optical mask. Different dependences among power and microwave/noise performances on the SiN thickness of the Γ-gate devices are also studied. The proposed design provides good potential for high temperature, high gain, and high linearity circuit applications.