Multi-field effect on the electronic properties of silicon nanowires

The quantum confinement and electronic properties of silicon nanowires (SiNWs) under an external strain field ε and an electric field E-as well as both (ε plus E)-are systematically investigated using density functional theory. These two fields exist in working environments of integrated circuits. It is found that both ε and E lead to a drop of the band gap E(g)(ε,E) of the SiNWs. If both fields coexist, the interaction between ε and E causes that E(g)(ε,E) becomes orientation-dependent, which results from variations of both the conduction-band minimum and the valence-band maximum. The interaction is further illustrated by the density of states near the Fermi level and the eigenvalue of the highest occupied molecular orbital.