Simulation of Phonon Interfacial Transport in Strained Silicon-Germanium Heterostructures

Abstract

A nonequilibrium Green’s function (NEGF) method is used to simulate the phonon transport across a strained thin film between two semi-infinite contacts. The calculation of dynamical matrix, self-energy matrix and transmission function are discussed. Uncoupled Green’s functions are computed numerically using a block tridiagonal algorithm. The numerical role of the broadening constant is investigated. The bulk density of states in a single atomic chain is calculated and compares well with an analytical solution. The transmission function and thermal conductance across the thin film are evaluated for two different configurations (Ge-Si-Ge and Si-Ge-Si) and compared against homogeneous bulk systems (Si only and Ge only), indicating that heterogeneous interfaces reduce thermal conductance significantly.