Quasi-ballistic thermal conduction in 6H–SiC

The minimization of electronics makes heat dissipation related devices an increasing challenge. When the size materials is smaller than phonon mean free paths, phonons transport without internal scatterings and laws diffusive thermal conduction fail, resulting in significant reduction effective conductivity. This work reports, for first time, temperature dependent conductivity doped epitaxial 6H-SiC monocrystalline porous below room probed by time-domain thermoreflectance. Strong quasi-ballistic was observed these samples, especially at low temperatures. Doping structural boundaries were applied to tune since dopants selectively scatter high-frequency while with long paths. Exceptionally strong scattering boron are observed, compared nitrogen dopants. Furthermore, orders magnitude measured temperatures 6H-SiC. Finally, principles calculations a simple Callaway model built understand conductivities. Our sheds light on fundamental understanding technologically-important wide bandgap semiconductors such as will impact applications management 6H-SiC-related devices.