In this paper, we investigate low-temperature thermal conductance in three-dimensional nanowire embedded with phonon cavity based on the full scalar model of elasticity. The results show that at very low temperatures, the cavity can enhance the thermal conductance in certain lateral-width range, just as the constructive coupling of more phonon-modes excited in the cavity with modes in the transport region. At higher temperatures, however, the scattering of more interfaces formed from the cavity become a dominant factor to suppress the phonon tr...
