With miniaturization in size, thermal transport is becoming increasingly important in the design and realization of micro-electronic devices. Due to additional scattering of heat carriers at boundaries, the thermal conductivity of material is reduced in these devices. While the reduced thermal conductivity deteriorates device performance and could result in device failure for applications such as microprocessors, it is advantageous for thermoelectric energy conversion, where the figure of merit is inversely proportional to the thermal conductivity.

Our objective is to understand and predict the thermal transport physics in technologically important materials by using first-principles based density functional theory calculations and the Boltzmann transport equation. We consider phonon-phonon scattering in semiconductors and phonon-phonon and phonon-electron scattering in metals. The scattering rates are obtained using the Fermi golden rule. We study the phonon thermal transport properties in (i) Conventional semi-conductors such as silicon and germanium, (ii) Semiconductor nanostructures (silicon nano-porous films) (iii) Two-dimensional semiconductor (phosphorene), and (iv) Metals (aluminum and gold). Our predicted values of thermal conductivities show excellent agreement with the experimentally measured values (wherever available) without the use of any fitting parameters.