Capacitor-type thin-film heat flow switching device

Abstract

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 device consisted of an amorphous p-type Si–Ge–Au alloy layer, an amorphous SiO2 as the dielectric layer, and an n-type Si substrate. Both amorphous materials are characterized by very low lattice thermal conductivity, ≤1 W m–1 K–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 SiO2 layer formed at the top surface of Si substrate. Bias voltage-dependent heat flow density through the fabricated device was evaluated by a time-domain thermoreflectance method at room temperature. Consequently, we observed a 55% increase in the heat flow density at the maximum.