External Electric Field Modulated Electronic and Structural Properties of 〈111〉 Si Nanowires

The effects of external electric field F on band gap E g ( D, F ) of silicon nanowires (SiNWs) in a diameter range of D = 0.45−1.79 nm are quantitatively calculated using density functional theory. The results show that E g ( D, F ) decreases with increasing F due to the rapid drop of the conduction band maximum of SiNWs. As F increases, E g ( D, F ) → 0 except at D = 0.45 nm. Further increasing of F results in breakdown of the geometry structure of SiNWs. In addition, the bond lengths and angles of SiNWs are also functions of F . These findings imply that E g ( D, F ) functions of SiNWs can be modulated by manipulating D and F .