2, Oregon State University, Corvallis, Oregon, United States
Researchers have recently developed processes for synthesizing monolithic Si with improved thermoelectric figure-of-merit ZT. These materials obtain higher ZT through a fine dispersion of nanoscale carbide particles. In this work we elucidate the role these particles play in two processes to increase ZT: (1) scattering of phonons to reduce thermal conductivity, and (2) energy selective scattering of electrons to increase the seebeck coefficient. A multiscale approach is used model the former process. Molecular dynamics simulations were used to quantify inclusions’ scattering cross cross-section for phonons, and this fed to Boltzmann transport simulations to predict the collective effect of the particle dispersion close to the Knudsen regime. To model electron energy filtering a semiclassical Boltzmann transport model was developed and used phenomenologically to predict the optimal energy filtering threshold for improving thermoelectric power factor. Together, these models provide guidance to researchers working to engineering high ZT in bulk Si.