Calculation of phonon spectrum and thermal properties in suspended 〈100〉 In X Ga1−X As nanowires

Abstract

The phonon spectra in zinc blende InAs, GaAs and their ternary alloy nanowires (NWs) are computed using an enhanced valence force field (EVFF) model. The physical and thermal properties of these nanowires such as sound velocity, elastic constants, specific heat (C v ), phonon density of states, phonon modes, and the ballistic thermal conductance are explored. The calculated transverse and longitudinal sound velocities in these NWs are ~25% and 20% smaller compared to the bulk velocities, respectively. The C v for NWs are about twice as large as the bulk values due to higher surface to volume ratio (SVR) and strong phonon confinement in the nanostructures. The temperature dependent C v for InAs and GaAs nanowires show a cross-over at 180°K due to higher phonon density in InAs nanowires at lower temperatures. With the phonon spectra and Landauer's model the ballistic thermal conductance is reported for these III---V NWs. The results in this work demonstrate the potential to engineer the thermal behavior of III---V NWs.