First-principles quantitative prediction of the lattice thermal conductivity in random semiconductor alloys: The role of force-constant disorder

摘要

The standard theoretical understanding of the lattice thermal conductivity,$kappa_{ell}$, of semiconductor alloys assumes that mass disorder is the mostimportant source of phonon scattering. In contrast, we show that the hithertoneglected contribution of force-constant (IFC) disorder is essential toaccurately predict the $kappa_{ell}$ of those polar compounds characterizedby a complex atomic-scale structure. We have developed an emph{ab initio}method based on special quasirandom structures and Green's functions, andincluding the role of IFC disorder, and applied it in order to calculate the$kappa_{ell}$ of $mathrm{In_{1-x}Ga_xAs}$ and $mathrm{Si_{1-x}Ge_x}$alloys. We show that, while for $mathrm{Si_{1-x}Ge_x}$, phonon-alloyscattering is dominated by mass disorder, for $mathrm{In_{1-x}Ga_xAs}$, theinclusion of IFC disorder is fundamental to accurately reproduce theexperimentally observed $kappa_{ell}$. As the presence of a complexatomic-scale structure is common to most III-V and II-VI random semiconductoralloys, we expect our method to be suitable for a wide class of materials.