Orientation-Dependent Stability and Quantum-Confinement Effects of Silicon Carbide Nanowires

The energetic stability and electronic properties of hydrogenated silicon carbide nanowires (SiCNWs) with zinc blende (3C) and wurtzite (2H) structures are investigated using first-principles calculations within density functional theory and generalized gradient approximation, The [111]-orientated 3C-SiCNWs are energetically more stable than other kinds of NWs with similar size. In contrast to the indirect band gap features of SiC bulk crystals, all the NWs have direct band gaps except those orientating along the [112] direction. The band gaps of these NWs decrease with the increase of wire size. The direct band gap can be kept for the [111]orientated 3C-SiCNWs with diameters up to 2.8 nm. The superior stability and electronic structures of the 3C-SiCNWs growing along the [111] direction are in good agreement with the experimental results.