InAs/In1-xGaxAs Composite Channel High Electron Mobility Transistors for High Speed Applications

80-nm InAs channel HEMTs with different lattice matched sub-channels, In_0.53Ga_0.47As and In_0.7Ga_0.3As, have been fabricated. The device with InAs/In_0.7Ga_0.3As composite channel exhibits high drain current density (1101 mA/mm), and high transconductance (1605 mS/mm) at drain bias V_DS = 0.8 V. The high current gain cutoff frequency (f_t) of 360 GHz and maximum oscillation frequency (f_max) of 380 GHz of the device with InAs/In_0.7Ga_0.3As were obtained at V_DS = 0.7 V in comparison to the InAs/In_0.53Ga_0.47 As channel HEMTs with f_t = 310 and f_max = 330 GHz. This is due to the high electron mobility and electron confinement in the InAs/In_0.7Ga_0.3As channel. In addition, a low gate delay time 0.84 psec was obtained at V_DS = 0.5 V. The excellent performance of the InAs channel HEMTs demonstrated in this study shows great potential for high speed and very low power logic applications with the optimal design of In_0.7Ga_0.3As/InAs/In_0.7Ga_0.3As composite channel.