An ultra clean self-aligned process for high maximum oscillation frequency graphene transistors

Owing to its ultra high carrier mobility, graphene transistor shows great application potential as high-frequency electronics. Intrinsic cutoff frequency (fT) of 427 GHz has been reported. But the maximum oscillation frequency (fmax) remains low, limiting its use in practical radio-frequency (RF) circuits. Here, we report an ultra clean self-aligned graphene transistors fabrication by pre-deposition of gold film on graphene as protection layer. This improved self-aligned fabrication keeps graphene away from any possible contamination, which makes our graphene transistors show good gate coupling and less parasitics, thus good dc and RF performances. The 100 nm gate-length graphene transistor exhibits a fmax of 105 GHz. Our study shows a pathway to fabrication of high-performance graphene transistors for future application in RF circuits.