  Bilayer graphene is an attractive material that realizes high-quality
two-dimensional electron gas with a controllable bandgap. By utilizing the
bandgap, electrical gate tuning of the carrier is possible and formation of
nanostructures such as quantum dots have been reported. To probe the dynamics
of the electronics states and realize applications for quantum bit devices,
RF-reflectometry which enables high-speed electric measurements is important.
Here we demonstrate RF-reflectometry in bilayer graphene devices. We utilize a
micro graphite back-gate and an undoped Si substrate to reduce the parasitic
capacitance which degrades the RF-reflectometry. We measure the resonance
properties of a tank circuit which contains the bilayer graphene device. We
form RF-reflectmetory setup and compared the result with the DC measurement,
and confirmed their consistency. We also measure Coulomb diamonds of quantum
dots possibly formed by bubbles and confirm that RF-reflectometry of quantum
dots can be performed. This technique enables high-speed measurements of
bilayer graphene quantum dots and contributes to the research of bilayer
graphene-based quantum devices by fast readout of the states.
