Thermal Rectification in Telescopic Nanowires: Impact of Thermal Boundary Resistance

A thermal diode, which, by analogy to its electrical counterpart, rectifies heat current, is the building block for thermal circuits. To realize a thermal diode, we demonstrate thermal rectification in a GaAs telescopic nanowire system using the thermal bridge method. We measured a preferred direction of heat flux, achieving rectification values ranging from 2 to 8% as a function of applied thermal bias. We demonstrate that the thermal boundary resistance between the thin part with the wurtzite crystal phase and the thick part with the zinc-blende crystal phase of the telescopic nanowire plays a crucial role in determining the amount and direction of heat flux rectification. This effect is confirmed by numerical solutions of the one-dimensional heat equation based on ab initio data. Additionally, we accounted for the effect of the thermal contact resistance. This work is the first experimental indication of rectification using a telescopic nanowire where we reveal the importance and role of the thermal boundary resistance in determining thermal rectification.