Epitaxial graphene FETs on sapphire substrate

In this letter, we report the first wafer-scale epitaxial graphene field-effect transistor (FET) grown and fabricated on 2-inch sapphire (0001) substrate by chemical vapor deposition (CVD) without a metal catalyst. The monolayer structure of the epitaxial graphene was confirmed by Raman spectra. Room temperature Hall effect mobility was 1,500 cm
²
/V·s. The maximum drain source current (I
_ds
) of 0.78 A/mm and peak transconductance of 0.13 S/mm were obtained at V
_ds
= -1 V for the graphene FET with gate length of 100 nm. The cutoff frequency (f
_T
) and maximum oscillation frequency (f
_max
) reached 24 GHz and 26 GHz after de-embedding, respectively, which are the first epitaxial graphene-on-sapphire FET showing RF performance. Our work proves out the promise of epitaxial graphene on sapphire substrate.