Sungyeb Jung, The University of Texas at Austin

"Thermal conductivity and electron phonon interaction”

Abstract: Heat dissipation is an increasingly important issue in the design of new generations of electronic and optoelectronic devices. In this context, new high thermal conductivity materials are highly desirable to reduce the power density of hot spots in ultra scaled transistors. Recently, a first principle study has found that the lattice thermal conductivity of semimetallic tantalum nitride in the θ phase θ TaN) can be as high as 1000Wm 1 K 1 and an experimental study has synthesized the θ TaN polycrystal samples and observed that the thermal conductivity of the experimental samples is primarily limited by grain boundary scattering. H ere, by using density functional theory DFT calculations, I will discuss a detailed computational study of the thermal conductivity o f θ TaN series compounds , such as hafnium nitride (HfN) and tantalum carbide (TaC). In addition, I will introdu ce the overscreening problem of phonon linewidth and propose the most recent approximation methods to calculate overscreening-free phonon line width within DFT implementation.