Structural and lasing characteristics of ultrathin hexagonal ZnO nanodisks grown vertically on silicon-on-insulator substrates

Hexagonal ZnO nanodisks were grown on silicon-on-insulator substrates by vapor-transport method without catalysts. The resulting nanodisks possess ultrathin thickness (10-20 nm) and most of them present vertical orientation on the substrate surface. Under optical excitation, these ultrathin nanodisks exhibit ultraviolet lasing emission with the excitation threshold of 205 mu J/cm(2) and emission lifetime of 2 ps at room temperature. The detailed lasing analysis indicates that whispering-gallery-mode lasing may occur in the ZnO nanodisks. (c) 2007 American Institute of Physics.