The rapid advance in modern electronics and photonics is pushing device design to the micro- and nano-scale, and the resulting high power density imposes immense challenges to thermal management. When device size shrinks to the same order of or even below the wavelength or mean-free-path of heat carriers, the transport of heat carriers and the interaction between them will differ from those in the macroscopic regime. This imposes challenges on designing micro/nano-devices with required thermal performance, while, at the same time, also opens the door for designing novel materials and structures with promising thermal properties
