Growth and great UV emission improvement of highly crystalline quality core-shell ZnO/MgO nanowires

The highly crystalline core-shell ZnO/MgO nanowires (NWs) were achieved by using a two-step CVD method. The related crystal growth model is proposed. The epitaxial growth of cubic MgO shells on the surfaces of hexagonal ZnO NWs benefits from the close interplanar distances of MgO (111) and ZnO (0002) planes. Comparing with bare ZnO NWs, more than 10 times enhancement of ultraviolet (UV) emission intensity is obtained from ZnO/MgO NWs with a shell thickness of 25 nm, owing to the improvement of crystal quality of ZnO NWs surface layers and the passivation of remained surface defects after forming high crystallization MgO shells. (C) 2012 Elsevier B.V. All rights reserved.