Size Dependence Lattice Thermal Conductivity for Si Nanofilm

The lattice Thermal Conductivity for silicon nanofilm with a thickness of 20 and 100nm has been calculated theoretically over wide range of temperature. The modified Debye-Callaway model depending on the size dependence lattice volume and Debye temperature was used. In this calculation, both longitudinal and transverse modes are taken into account. Numerical results, predicate a significant decrease more than an order of magnitude of the lattice thermal conductivity for all thickness and it is due to the change of lattice volume, acoustic phonon confinement and roughness of boundary scattering. Theoretical results are in a good agreement with experimentally observed drop of the lattice thermal conductivity in silicon low dimensional structures.