Extended Hückel theory for band structure, chemistry, and transport. II. Silicon

Abstract

In this second paper, we develop transferable semiempirical extended Hückel theoretical (EHT) parameters for the electronic structure of another technologically important material, namely, silicon. The EHT parameters are optimized to experimental target values of the band dispersion of bulk silicon. We quantitatively benchmark our parameters to bulk electronic properties such as band edge energies and locations, effective masses, and spin-orbit coupling parameters, competitive with a nearest-neighbor sp3d5s* orthogonal tight-binding model for silicon of T. Boykin et al. [Phys. Rev. B 69, 115201 (2004)] that has been widely used to model silicon-based devices (see, e.g., A. Rahman et al. [Jpn. J. Appl. Phys. Part I 44, 2187 (2005)] and J. Wang et al. [Appl. Phys. Lett. 86, 093113 (2005)]). The transferability of the parameters is checked for multiple physical and chemical configurations, specifically, two different reconstructed surfaces, Si(100)-(2×1) and Si(111)-(2×1). The robustness of the parameters to different environments is demonstrated by comparing the surface band structures with density functional theory GW calculations and photoemission/inverse photoemission experiments. We further apply the approach to calculate the one-dimensional band dispersion of an unrelaxed rectangular silicon nanowire and explore the chemistry of surface passivation by hydrogen. Our EHT parameters thus provide a quantitative model of bulk silicon and silicon-based interfaces such as contacts and reconstructed surfaces, which are essential ingredients towards a quantitative quantum transport simulation through silicon-based heterostructures.