Near-junction thermal managements of electronics

Near-junction thermal management of electronics has received a lot of attention in the past decades but there are still many challenges in this area. This chapter provides a comprehensive review of recent developments in this field. The reduction of scale of devices will result in the crossover of heat transport from the diffusive regime to the ballistic regime. Thus, boundary temperature jumps and boundary heat flux slips emerge. A set of predictive models are developed and verified through comparisons with Monte Carlo method, which will be discussed in detail in this chapter. The thermal conductivity of nanostructures will also deviate from their bulk counterparts. Conductivity is found to depend significantly on multiple factors, including characteristic size and geometry, heating conditions, interfacial effects, stress, and electric fields. Various cases are considering for thermal spreading resistance in electronic devices, with particular emphasis on GaN HEMTs in a ballistic-diffusive regime from multiple perspectives. These cases contain the impacts of phonon ballistic effect, phonon dispersion, bias-dependent heat generation, and first-principle-calculated phonon properties on thermal spreading resistance. Finally, the self-heating effect caused by the scattering between the hot carrier and the lattice is analyzed. Research methods for the self-heating effect are introduced, including some theoretical models and electro-thermal simulations. And the methods for controlling the self-heating effect to improve device performance, reliability, and lifespan are given as well. The present chapter mainly presents some of the most recent progresses for near-junction thermal management of electronics.