Nanoscale simulation of heat conduction in semiconductor devices

Localized heat generation, with dimensions of the order of 10 nm, takes place in the drain regions of current transistors, resulting in an increase in thermal resistance near such a hotspot. We present a model based on the phonon Boltzmann transport equation (BTE) that agrees well with data for hotspots in simple geometries. The model suggests that scattering rates of optical phonons are key to the conduction physics. We use molecular dynamics to obtain phonon relaxation rates and show their dependence on the energy density in the hotspot. This work improves the constitutive modeling of heat flow in nanoscale devices.