  We developed a capacitor type heat flow switching device, in which electron
thermal conductivity of the electrodes is actively controlled through the
carrier concentration varied by an applied bias voltage. The devices consist of
an amorphous p-type Si-Ge-Au alloy layer, an amorphous SiO$_2$ as the
dielectric layer, and a n-type Si substrate. Both amorphous materials are
characterized by very low lattice thermal conductivity, less than 1 Wm-1K-1.
The Si-Ge-Au amorphous layer with 40 nm in thickness was deposited by means of
molecular beam deposition technique on the 100 nm thick SiO$_2$ layer formed at
the top surface of Si substrate. Bias voltage-dependent thermal conductivity
and heat flow density of the fabricated device were evaluated by a time-domain
thermoreflectance method at room temperature. Consequently, we observed a 55
percent increase in thermal conductivity.
