Heat transport in 2D materials measured by time-domain thermoreflectance

17. 연사소개: Dr. Hyejin Jang
             Postdoctoral scholar at the University of California, Berkeley in USA
17. 장    소: 충무관 209A
17. 시    간: 2019. 10. 22. (화) AM 11:00

Abstract

The universal trend of modern electronics towards smaller and faster devices gives rise to ever-increasing power density. Thus, knowledge of heat transport in device components is crucial for efficient and reliable operation of nano-scale devices. Since 2014, layered van der Waals materials having distinct in-plane anisotropy have been successfully prepared in the form of mono- or few-atomic-layers and considered as promising candidates for next-generation electronics. These materials include black phosphorus (BP), WTe₂, and ReS₂. In this talk, I will present how the thermal conductivities of the three materials along the crystalline axes are measured, for the first time, by using an ultrafast optical pump-probe technique, i.e., time-domain thermoreflectance (TDTR). [1–3] As expected from the layered structures, in-plane heat transport is superior to through-plane heat transport by an order of magnitude. Also, the interface of the 2D materials with metals shows very low thermal conductance, which can seriously limit cooling of the 2D materials in devices. I will also show that the ultralow thermal conductivity among dense solids is demonstrated in 2D materials when SnSe₂/MoSe₂ layers are stacked alternatively with turbostratic disorder. [4]