Tunable electronic band structures of hydrogen-terminated ⟨112⟩ silicon nanowires

The possibility of inducing indirect-to-direct band gap transition in silicon nanowires (SiNWs) by changing wire diameter is well known. Here, we show that for < 112 >-oriented SiNWs indirect-to-direct band gap transition can be tuned simply by changing the wire cross-section shape or the cross-sectional aspect ratio of the (111) and (110) facets that enclose the wire, instead of changing the wire diameter. The cross-sectional aspect ratio must be smaller than 0.5 in order to maintain a direct band gap, indicating the important role of the (110) facet. (C) 2008 American Institute of Physics.