Remarkable effects of surface dihydride configurations in electronic properties of 〈 110 〉 silicon nanowires

Based on density functional theoretical calculations, we present remarkable differences in the electronic properties of 〈110 〉 silicon nanowires (SiNWs) with symmetric and canted dihydrides (SiH2) on (100) facets which are, however, energetically very competitive. It is found that surface terminations with the canted SiH2 result in dramatic widening of the band gap, with an increment as large as 20%. The valence band maximum diffuses in the surface layers, which enhances the electronic activity of surface defects. The revealed significant effects of the surface multistates could be important for the surface functionization of SiNWs.