Orientation-Dependent Energy Bandstructure Calculation for Silicon Nanowires Using Supercell Approach with the Tight-Binding Method

The Tight-Binding (TB) model has been applied to investigate the bandstructures for semiconductor nanowires. With a specific implementation of SP³d⁵s* in the TB method, the orientation dependence of nanowire bandstructures can be quickly and accurately evaluated. It is found that while most axial directions of nanowires preserve the indirect band gap of bulk silicon, particular orientation can render direct band gap feature. In this paper, a [112] oriented silicon nanowire has been simulated using supercell approach and compared to the available measured data. The good agreement shows the proposed method is highy reliable and efficient.