Synthesis and physical characteristics of AlOx-coated ZnO nanorod arrays grown in aqueous solution at low temperatures

AlOx-ZnO core-shell nanorods arrays have been successfully synthesized by soaking the ZnO nanorods in the sol-gel solution of Al(NO3)3 and NH4OH at room temperature. It was found that both crystal growth and morphology of the AlOx-ZnO core-shell nanorods are strongly influenced by the solution pH value. SEM image shows that the AlOx-ZnO core-shell nanorods can be perpendicularly grown on the ZnOf/Si substrate under the solution only with a pH value of 6-7. High-resolution TEM observation demonstrates that the structure of the AlOx layer is amorphous and the ZnO nanorod core remains single crystal. After annealed at 400 °C in N2 atmosphere, a strong photoluminescence peak corresponding to blue emission (∼450 nm) was detected from the AlOx-ZnO core-shell nanorods that may result from the induced defects due to interaction between AlOx shell and ZnO nanorods.