Boundaries, interfaces, point defects, and strain as impediments to thermal transport in nanostructures
The ability to grow heterostructures with high-quality interfaces brings great flexibility to the design and development of modern electronic and optoelectronic devices. While nearly perfect from an electronic standpoint, these interfaces are exceedingly disruptive to thermal transport and are a major contributor to anisotropic heat conduction and localized heating. Doping, alloying, and strain — all commonly employed when tailoring the electronic and optical properties of heterostructures — are also highly detrimental to the transport of phonons, the dominant carriers of heat in semiconductors. From the theoretical standpoint of phonon dynamics in disordered systems, we discuss the present understanding of nanoscale thermal transport and its profound sensitivity to any deviation from single-crystallinity. The roles that boundaries, interfaces, point defects, and strain play in thermal transport and localized heating are illustrated on several examples of semiconductor nanostructures, such as nanowires, thin films, superlattices, and quantum cascade lasers.