Thermal Modelling of GaN & InP RF Devices with Intrinsic Account for Nanoscale Transport Effects

Microscale thermal transport is no longer diffusive as the feature size of the devices becomes comparable with the mean free paths of the heat carriers. We present a Monte Carlo modelling framework with partial experimental validation that captures those effects from first principles in complex 3D transistor geometries. Steady state and transient simulation case studies on GaN HEMTs and InP nanoridge HBTs reveal peak temperature rises that are up to threefold larger than conventional predictions based on bulk diffusion.