Strain effects on the thermal properties of ultra-scaled Si nanowires

The impact of uniaxial and hydrostatic stress on the ballistic thermal conductance ($\kappa_{l}$) and the specific heat ($C_{v}$) of [100] and [110] Si nanowires are explored using a Modified Valence Force Field phonon model. An anisotropic behavior of $\kappa_{l}$ and isotropic nature of $C_{v}$ under strain are predicted for the two wire orientations. Compressive (tensile) strain decreases (increases) $C_{v}$. The $C_{v}$ trend with strain is controlled by the high energy phonon sub-bands. Dominant contribution of the low/mid (low/high) energy bands in [100] ([110]) wire and their variation under strain governs the behavior of $\kappa_{l}$.