  Hexagonal boron nitride (h-BN) encapsulation significantly improves carrier
transport in graphene. This work investigates the benefit of implementing the
encapsulation technique in graphene field-effect transistors (GFET) in terms of
their radio frequency (RF) performance. For such a purpose, a drift-diffusion
self-consistent simulator is prepared to get the GFET electrical
characteristics. Both the mobility and saturation velocity information are
obtained by means of an ensemble Monte Carlo simulator upon considering the
relevant scattering mechanisms that affect carrier transport. RF figures of
merit are simulated using an accurate small-signal model that includes
non-reciprocal capacitances. Results reveal that the cutoff frequency could
scale up to the physical limit given by the inverse of the transit time.
Projected maximum oscillation frequencies, in the order of few THz, are
expected to exceed the values demonstrated by InP and Si based RF transistors.
The existing trade-off between power gain and stability and the role played by
the gate resistance are also studied. High power gain and stability are
feasible even if the device is operated far away from current saturation.
Finally, the benefits of device unilateralization and the exploitation of the
negative differential resistance region to get negative-resistance gain are
discussed.
