Abstract: For the past decade, research on graphene and other two-dimensional atomic crystals has attracted attention from scientists and engineers from multiple disciplines. These two-dimensional materials are bonded to the substrates, metal contacts and other 2D materials (e.g., in Van-der-Waals heterostructures) mostly by van-der-Waals forces. Among other properties, heat transport across the interfaces bonded by van-der-Waals forces is still relatively less understood. In this presentation, I will focus on presenting our recent results in understanding and tailoring electronic and phononic heat transport across van-der-Waals interfaces and structures. I will start by comparing the thermal conductance of Al/graphene/Cu interfaces, for both as-grown and transferred graphene. I will then discuss our efforts to determine the role of remote interfacial phonons (RIP) scattering in heat transport across graphene/SiO2 interfaces. Then, I will present a graphene-based heterostructure with ultralow thermal conductivity of <0.1 W/m-K. Finally, I will discuss anisotropic heat transport in black phosphorus with puckered basal atomic planes bonded by van-der-Waals forces. Our work could facilitate better thermal management of electronic and optoelectronic devices of 2D materials, and could be important for new thermoelectric materials based on 2D materials.

Bio: Yee Kan Koh received a B.S. and a M.Eng. in Mechanical Engineering from the University of Technology Malaysia. In 2004, he enrolled in the University of Illinois at Urbana-Champaign, and obtained a M.S. in Physics in 2007 and a Ph.D. in Materials Science and Engineering in 2010 from the university. After his graduation in 2010, Koh joined the Department of Mechanical Engineering in National University of Singapore (NUS) as an assistant professor. Koh’s expertise is in heat transport in nanostructures and across interfaces, with emphasis on applications in thermoelectric energy conversion and thermal management of emerging electronic devices (e.g., graphene devices). Koh is an expert in time-domain thermoreflectance (TDTR), a modulated pump-probe technique to measure heat conduction on nanometer length scales. He has received numerous awards, including the NUS Young Investigator Award (2011), the SMF-NUS Research Horizons Award (2010) and the Ross J. Martin award (2010).