Controllable Growth and Characterization of ZnO/MgO Quasi Core-Shell Quantum Dots

ZnO/MgO quasi core-shell quantum dots (QDs) were grown by a metal-organic chemical vapor deposition method on silicon substrates. The core-shell structure was well-characterized by a combination of cross-sectional transmission electron microscopy and angle-resolved X-ray photoelectron spectroscopy (XPS). Valence band XPS measurements were performed to investigate the effects of MgO shell layer on the energy band of ZnO/MgO QDs. Photoluminescence (PL) emission from the QDs showed remarkable enhancement after the growth of the MgO layer. In addition, exciton binding energy of 118 +/- 5 meV in the ZnO/MgO QDs was obtained from temperature-dependent PL.