Engineering of Heat Flow in Nanoscale Devices

Thermal dissipation and heating limit the performance of many state-of-the-art electronic, MEMS, and acoustic devices and integrated circuits. Full-field thermoreflectance imaging measures the dynamic temperature of active devices with sub-nanosecond time resolution. The hyperspectral technique separates the temperature-induced sample movement from thermoreflectance. We present evidence for quasi-ballistic superdiffusive and hydrodynamic transport of heat in alloys. We also describe solid-state micro-refrigerators that can selectively cool hot spots. Non-equilibrium electron gas expansion can significantly increase efficiency by decoupling electrons and the lattice.