20-nm T-gate composite channel enhancement-mode metamorphic HEMT on GaAs substrates for future THz applications

In this paper, the RF and DC behaviours of a SiN-passivated 20-nm gate length metamorphic high electron mobility transistor (MHEMT) on GaAs substrate with -doped sheets on either side of the composite channel are studied using the Synopsys TCAD tool. The 20-nm enhancement-mode MHEMT with -doped sheets on either side of the /InAs/ multilayer channel shows a transconductance of 3000 mS/mm, cut-off frequency () of 760 GHz and a maximum-oscillation frequency () of 1270 GHz. The threshold voltage of the device is found to be 0.07 V. The room-temperature Hall mobilities of the two-dimensional sheet charge density (2DEG) are measured to be over /Vs with a sheet charge density larger than 4 . These high-performance enhancement-mode MHEMTs are attractive candidates for future terahertz applications such as high-resolution radars for space research and also for low-noise wide-bandwidth amplifier for future communication systems.