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 ${\kappa }_l$.