Electronic structures and optical properties of GaN and ZnOnanowires from first principles

Electronic structures and optical properties of GaN and ZnO nanowires with diameters of ∼1 nm are investigated using the highly precise all-electron full-potential linearized augmented plane-wave (FLAPW) method. The calculated results demonstrate that the band gap energy of both passivated and unpassivated nanowires becomes large compared with the calculated bulk energy gap due to quantum confinement effects. Furthermore, the calculated imaginary part of their dielectric functions exhibit strong anisotropy and there are several side peaks near the absorption edge caused by valence electronic states around the highest-occupied band involved in the large dipole matrix elements. These results demonstrate that we have a firm theoretical framework to predict microscopic properties of semiconductor nanowire.