First-principles study of the electronic and optical properties of ZnO nanowires

The geometric, energetic, electronic structures and opticalproperties of ZnO nanowires (NWs) with hexagonal cross sections areinvestigated by using the first-principles calculation of plane waveultra-soft pseudo-potential technology based on the densityfunctional theory (DFT). The calculated results reveal that theinitial Zn-O double layers merge into single layers after structuralrelaxations, the band gap and binding energies decrease with theincrease of the ZnO nanowire size. Those properties show greatdimension and size dependence. It is also found that the dielectricfunctions of ZnO NWs have different peaks with respect to lightpolarization, and the peaks of ZnO NWs exhibit a significantblueshift in comparison with those of bulk ZnO. Our results givessome reference to the thorough understanding of optical propertiesof ZnO, and also enables more precise monitoring and controllingduring the growth of ZnO materials to be possible.