Understanding the ballistic-diffusive thermal transport trends in crystalline semiconductors with molecular dynamics

Abstract

Due to the growing demand of the market, semiconductor device size decreases and power density increases continuously. In today's semiconductor devices, extremely small architecture and localized heating distrupt energy carrier's movements and thermal transport. Consequently, device temperature becomes higher which leads to degraded device performance and lifetime. Hence, thermal transport deviates from the continuum behavior and the thermal conductivity of materials is reduced. A rigorous understanding of size effects is a necessity to build an effective thermal management strategy. Current experimental and theoretical characterization methods need a significant amount of time and effort. Thus, there is a need for simple relations to characterize the size effects and relate them to the existing phonon data. To do that, the trends in ballistic – diffusive thermal transport regime and its effect on thermal transport properties of thin films, interfaces, and localized heating regions are investigated using molecular dynamics simulations. The relations between material and phonon properties and trends in ballistic - diffusive thermal transport regime in semiconductor materials are discovered for three cases. Obtained relations provide a simple alternative to characterize the size effect in thermal transport in semiconductor devices.