Surface chemical control of the electronic structure of silicon nanowires: Density functional calculations

Silicon nanowires (NWs) have potential use in many electronic and photonic applications. In this study, we have systematically investigated the modification of Si NW electronic structure for different sized NWs and different surface coverage (H, Br, Cl, and I) using ab initio density functional theory calculations. The surface chemistry is shown to have strong effects, comparable to that of quantum confinement, on the band structure of Si NWs. Electronic structure analysis reveals the primary cause of the band gap change is the suppression of surface states as determined by the strength of the surface bonds. The results elucidate surface chemical control of NW electronic structure and illustrate an example of simulation-based design characterization of nanoelectronic components.