Two-dimensional (2D) and thin-film materials have been widely used in nanoelectronics and energy-related applications, owing to their novel electronic and thermal properties. Tailoring their thermal conductivity can be viewed to optimize heat dissipation and improve performance for high-power-density applications. The thermal transport in 2D/thin-film materials can be manipulated along the "phonon engineering method" or "elastic strain engineering method". In the 1st part of phonon engineering in this talk, a new graphene-based nanocarbon film formed by introducing single-walled carbon nanotubes (SWCNTs) is studied for its unique temperature dependence of thermal conductivity. The study reveals the amorphous-like thermal conductivity trend of the nanocarbon composite films due to the SWCNT-graphene junctions. In the 2nd part of elastic strain engineering, thermal properties of the strained Si thin film are studied. At room temperature, an in-plane thermal conductivity reduction is found under the uniaxial tensile strain. The film also shows a high convective heat transfer coefficient, which evaluates the errors in previous in-air thermal measurements.
Qiyu Chen is a Ph.D. student in the Department of Aerospace and Mechanical Engineering at the University of Arizona. He received his M.S. and B.E. degrees from Xi’an Jiaotong University, China, in 2018. His research interests include the thermal/electronic transport properties of nanostructured 2D/thin-film materials and their applications.