Selective transport of ballistic phonon modes by an acoustic nanocavity in a Ψ-shaped semiconductor nanowire

We study theoretically ballistic phonon transport in a Psi-shaped semiconductor nanowire at low temperatures. When ballistic acoustic phonons propagate through the nanowire, the region connecting the left lead and the three right leads of the nanowire acts as a cavity. Acoustic waves interfere with each other in the nanocavity to form standing waves with particular wavelengths due to multiple reflection by the boundaries of the cavity. Owing to the presence of the split cavity, different phonon modes are found to transport selectively into different channels, and phonon heat can be dissipated through different channels by properly tuning the parameters of the structure. This structure may be a promising split device for the ballistic phonon modes and control the phonon heat transport in nanophononics. (c) 2008 American Institute of Physics.