Quantum confinement observed in ultrafine ZnO and ZnO/Zn0.8Mg0.2O coaxial nanorod heterostructures

We report on the fabrication and photoluminescent (PL) properties of ultrafine ZnO nanorods and ZnO/Zn_0.8Mg_0.2O coaxial nanorod heterostructures. Employing catalyst-free metalorganic vapor-phase epitaxy, ultrafine ZnO nanorods with very thin diameters below 10 nm were prepared and subsequently coaxial nanorod heterostructures were fabricated by epitaxial growth of Zn_0.8Mg_0.2O layers on the whole surfaces of the ZnO nanorods. From PL spectra of ultrafine ZnO nanorods, a systematic blue-shift in their PL peak position with decreasing their diameter was observed, which is mainly due to the quantum confinement effect along the radial direction in ZnO nanorods. Furthermore, the ZnO/Zn_0.8Mg_0.2O coaxial nanorod heterostructures exhibited significantly increased PL intensity.