Dr. Yashpreet Kaur

Nanophononics Group at the University of Basel, Switzerland

Asymmetric thermal transport and the impact of thermal contact resistance in designed nanowires 

Heat dissipation has become a critical problem in the performance of electronic devices, thus, reducing their lifespans. Therefore, to manipulate and control heat, thermal circuit elements analogous to the electronic ones like thermal diodes, transistors and thermal logic gates are needed. 

In our current research, we have experimentally studied telescopic nanowires (NWs) for their thermal rectification using the thermal bridge method. Thermal rectification ratios of up to 8% as a function of applied temperature bias were measured in telescopic NWs, thus, exhibiting thermal diode effect. The asymmetric heat transport is accounted through the mechanisms of the temperature dependence of the thermal conductivity and the thermal boundary resistance between the thick part and thin part of the NW. Furthermore, Raman thermometry technique combined with the thermal bridge method was used to tackle and quantify the highly prevalent issue of thermal contact resistance in measurements. The thermal mapping using Raman thermometry along the nanowire axis was done to estimate the thermal resistances in the thermal equivalent circuit of the system. 

This work provides experimental proof and deeper understanding of a new thermal rectification mechanism. In addition, we present a unique method to estimate thermal contact resistance in lowdimensional systems.