Passivation Effects of 100 nm In_(0.4)AlAs/In_(0.35)GaAs Metamorphic High-Electron-Mobility Transistors with a Silicon Nitride Layer by Remote Plasma-Enhanced Chemical Vapor Deposition

摘要

In_(0.4)AlAs/In_(0.35)GaAs metamorphic high-electron-mobility transistors (MHEMTs) have been successfully fabricated. In order to reduce the surface effects on the barrier layer, Si_3N_4 layer passivation by remote plasma-enhanced chemical vapor deposition (PECVD) is utilized, which might suppress the surface trap density in side-recessed region and reduce the parasitic resistance. The device simulation was performed to derive the effects of surface trap in the side-recessed region. As the surface trap density decreases, I_(D.max) increases because of the stabilization of the surface states in the side-recessed region. This result indicates that the increases of g_(m.max) and I_(D.max) are related with both the reduction of parasitic resistance and the gate-sinking effect. The fabricated 100 nm MHEMTs with the passivated of Si_3N_4 layer exhibited excellent characteristics such as a maximum extrinsic g_(m.max) of 740 mS/mm and a cut off frequency (f_T) of 210 GHz.