Lattice dynamics and thermal properties of phononic semiconductors

An enhanced adiabatic bond charge model has been employed to study the lattice dynamics of phononic metamaterials based on group-IV and group-III-V semiconductors. Using the full phonon spectrum and a realistic Brillouin zone summation method, we have developed theories of phonon scattering rates from interface formation and anharmonicity. Numerical results for specific-heat capacity and phonon conductivity of thin Si/Ge and GaAs/AlAs superlattices are then presented and compared with available experimental measurements. The roles of various phonon scattering mechanisms in controlling the thermal conductivity in different temperature ranges have been quantified.