Strong Ultraviolet Emission From MgO-core/ZnO-Shell Nanowires

초록

MgO-core/ZnO-shell nanorods were fabricated by thermal evaporation of Mg3N2 in an oxygen atmosphere and their photoluminescence was measured. Very strong ultraviolet emission (stronger in intensity than that of the original orange emission from the MgO nanorods by a factor of ~200) was obtained by the annealed MgO-core/ZnO-shell nanorods with a ZnO layer thickness of 20 nm. It is obvious that this UV emission comes from the ZnO shells. The enhancement of the emissions in intensity may be attributed to the transfer of the photogenerated carriers from the MgO core to the ZnO shell and the oscillator strength effect due to resonant cavities formed in the shell layers. In contrast, a strong yellow emission band centered at approximately 560 nm was observed from the as-synthesized MgO-core/ZnO-shell nanorods. This yellow emission does not seem to come from the MgO cores but from the ZnO shells.