  In this work, we propose a near-field radiative thermal transistor made of
two graphene-covered silicon carbide (SiC) plates separated by a nanometer
vacuum gap. Thick SiC plates serve as the thermal "source" and "drain", while
graphene sheets function as the "gate" to modulate the near-field photon
tunneling by tuning chemical potential with applied voltage biases
symmetrically or asymmetrically. The radiative heat flux calculated from
fluctuational electrodynamics significantly varies with graphene chemical
potentials, which can tune the coupling between graphene plasmon across the
vacuum gap. Thermal modulation, switching, and amplification, which are the key
features required for a thermal transistor, are theoretically realized and
analyzed. This work will pave the way to active thermal management, thermal
circuits, and thermal computing.
