MONTE CARLO TRANSPORT AND HEAT GENERATION IN SEMICONDUCTORS

Abstract

Understanding transport and energy use in nanoscale devices is essential for the design of low-power electronics and efficient thermoelectrics. This chapter examines transport physics and the electron-phonon interaction in the context of Monte Carlo simulations, which treat electrons and phonons with comparable attention to detail. The Monte Carlo method is described in depth, including scattering physics, electron energy band and phonon dispersions, Poisson solution, and contacts within realistic devices. This approach uncovers, for instance, that Joule heating in silicon devices is distributed between the (slow) optical and (fast) acoustic phonon modes by a ratio of two to one. In nanoscale transistors, nonequilibrium transport affects heat generation near strongly peaked electric fields, and Joule heating occurs almost entirely in the drain of short, quasi-ballistic devices. Evidence is also uncovered for thermionic cooling at the source terminal of transistors, and the physics of this phenomenon are described. Although the discussion is often with respect to silicon for specificity, key methods can be broadly applied to many semiconductor devices and structures. Such aspects are only expected to increase in importance as nanoscale devices are reduced to dimensions comparable to or smaller than the electron and phonon mean free paths (10−100 nm).