100-nm Gate-length GaAs mHEMTs using Si-doped InP/InAlAs Schottky layers and atomic layer deposition Al2O3 passivation with fmax of 388.2 GHz

100-nm gate length (Lg) In_0.52Al_0.48As/In_0.7Ga_0.3As metamorphic high-electron mobility transistors (mHEMTs) on GaAs substrates have been successfully fabricated and extensively studied. Epitaxial structure with Si-doped InP/InAlAs Schottky layers and atomic layer deposition (ALD) Al₂O₃ passivation were chosen in this study. Devices with 100-nm gate length and 2×25 pm gate width exhibit excellent DC and RF performance. A maximum drain current of 630 mA/mm, a peak transconductance of 580 mS/mm, a specific ohmic contact resistance of 0.026 Ω·mm, a unity current gain cut-off frequency (f_T) of 112.7 GHz, and a maximum oscillation frequency (f_max) of 388.2 GHz have been achieved. These excellent characteristics have made the 100-nm gate length GaAs mHEMTs well suitable for high frequency and high speed applications.