Lattice thermal conductivity of Si nanowires: Effect of modified phonon density of states

We investigate the size-dependent lattice thermal conductivity of silicon (Si) square cross-sectional and cylindrical nanowires. The calculation includes the modifications of the phonon density of states and group velocities due to phonon confinement. The decrease in phonon density of states and group velocities results in further thermal conductivity reduction in Si nanowires. By using suitable values of interface specularity parameters, the calculated thermal conductivities of Si square cross-sectional and cylindrical nanowires are found to be in good agreement with molecular dynamics and experimental results, respectively.