Fabrication, structure and luminescence properties of Al2O3/ZnO coaxial nanowires

초록

Al2O3/ZnO coaxial nanowires were successfully synthesized on (100) Si substrates by thermal evaporation of a mixture of Al and TiO2 powders followed by atomic layer deposition of ZnO. X-ray diffraction, scanning electron microscopy and ttanmission electron microscopy (TEM) analyses showed that the diameters and lengths of the coaxial nanowires were a few hundreds of nanometers and a few tens of micrometers, respectively, and the ZnO shell layer thickness ranged from 8 to 11 nm. TEM and X-ray diffraction analyses indicated that the cores and shells of the coaxial nanowires comprised a single crystal rhombohedral-structured a-Al2O3 and a polycrystallin simple hexagonal structured ZnO, respectively. Photoluminescence measurements revealed that the Al2O3 nanowires had a strong emission band centered at approximately 710 nm in a red region as well as a weak emission band centered at approximately 340 nm in a near-ultraviolet region. In contrast, Al2O3/ZnO coaxial nanowires had two emission bands: a strong emission band centered at approximately 570 nm in the yellow region and a weak emission band at approximately 340 nm in the near-ultraviolet region. The yellow emission might be from the ZnO shells in the Al2O3/ZnO coaxial. nanowires whereas the weak near-ultraviolet emission might be from the Al2O3 coaxial the core-shell nanowires.