Selective Crystalline Seed Layer Assisted Growth of Vertically Aligned MgZnO Nanowires and Their High-Brightness Field-Emission Behavior

This article reports a new approach for fabricating vertically aligned MgZnO nanowire arrays using selective crystalline seed layers deposited at relatively high temperatures by metalorganic chemical vapor deposition. In the phase-separated MgZnO seed layers, Zn-rich regions with a wurtzite structure allowed the growth of slim MgZnO nanowires, while the Mg-rich seeds with a cubic or amorphous-like structure hindered the formation of nanowires. The photoluminescence of these nanowires showed a remarkable increase in the activation energy of the excitons, ∼100 meV. The field-emission performance showed excellent emission behavior with extremely improved brightness, ∼80 times higher current density than that of the ZnO nanowires grown under the same conditions. Models for the growth evolution of slim nanowires on Si substrates were also proposed, based on microstructural characterization.