title: Variation of ZnO shell thickness and its effects on the characteristics of coaxial nanowires.
abstract: We have changed the thickness of the ZnO shell layers in SiO(x)/ZnO core-shell nanowires by increasing the atomic layer deposition (ALD) cycle, using diethylzinc (DEZn) and H(2)O as precursors of Zn and O, respectively. The samples were characterized by means of x-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and photoluminescence (PL) spectroscopy. While the thickness of the ZnO shell layers increased almost linearly with increase of the ALD cycle, their tubular morphologies were maintained. The variation in the thickness of the ZnO shell layers was accompanied by changes in the relative intensities of the characteristic ultraviolet (UV) and visible emission bands and by a shift of the UV peak position. On the basis of the observed relationship between the XRD shell grain size and the PL shift, we suggest that the PL shift is attributable to an exciton confinement effect. The findings in this study can be applied to a wide range of materials, and are expected to contribute to the development of potential applications of coaxial nanowires.
authors.forename: Hyoun Woo
authors.initials: HW
authors.lastname: Kim
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Shim
authors.forename: Jong Woo
authors.initials: JW
authors.lastname: Lee