Abstract
The bandstructure of ⟨110⟩⟨110⟩ silicon nano wires (SiNWs) with diameters (d) up to 6.1 nm were studied using density functional theory. Three types of surface termination were investigated: H, F, and OH; all giving quantum confinement induced direct bandgaps in the investigated size range. Comparison of the calculated results to reported experimental values showed that trends in the bandstructure behaviour were well reproduced. By studying the relative decrease of global and local minima in the conduction band minimum with increasing d, it was possible to predict a direct-to-indirect bandgap transition at d = 9.2, 9.5, and 11.4 nm for H, F, and OH terminated NWs, respectively.