Normally-off metamorphic AlInAs/AlInAs HEMTs on Si substrates grown by MOCVD

A combination of self-aligned fluoride-based plasma treatment and post-gate rapid thermal annealing was developed to fabricate a novel 120-nm T-shaped gate normally-off metamorphic Al0.49In0.51As/Ga0.47In0.53 As HEMT device on a Si substrate grown by metal-organic chemical vapor deposition(MOCVD). A shift of the threshold voltage, from-0.42 V to 0.11 V was obtained and the shift can be effectively adjusted by the process parameter of CF4 plasma treatment. Furthermore, a side benefit of reducing the leakage current of the device up to two orders of magnitude was also observed.E-mode transistors with 120 nm gate length own fTup to 160 GHz and fmax of 140 GHz. These characteristics imply the potential of the fluoride-based plasma treatment technology for the fabrication of monolithic enhancement/depletion-mode m HEMTs, which also encourage the massive production with this low-cost technology.