ZnO-cored heteronanowires sheathed with Cu shells: Structural, magnetic, and photoluminescence properties

Abstract

Copper (Cu) shell layers were sputter-coated on core ZnO nanowires to fabricate ZnO/Cu core-shell nanowires. The Cu shell was thermally annealed to form the nanoparticles of a cubic Cu phase on the stem nanowires. Although the magnetic hysteresis loops of the uncoated nanowires exhibited a weak ferromagnetism, the diamagnetic behavior was enhanced by the subsequent thermal annealing as well as the Cu-sputtering. The room-temperature PL spectrum of Cu-coated ZnO nanowires was comprised of 2.4 eV- and 3.2 eV-bands, whether the annealing has been performed or not. With those PL bands being ascribed to the ZnO core, the reduction and increase of green emission by the Cu coating and thermal annealing, respectively, were mainly related to the covering effect of the ZnO surface by the Cu shell. Since Cu doping into ZnO nano-structures will attract much interest and possibly change the structure, PL, and magnetic properties, the present study will be a significant contribution to both academic field and industrial applications. (C) 2012 Elsevier B.V. All rights reserved.