Browsing by Author "Liu, KH"

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Formation of Zn-ZnO polygon prismatic nanocrystals by liquid source via thermal vapor transport
(2005)
Liu, KH
;
Lin, CC
;
Chen, SY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A novel hierarchical polygon prismatic nanostructure of wurtzite Zn has been grown on silicon by liquid-solution seed nucleation and vapor-gas growth method. The Zn(ClO4)(2) colloidal sol with various concentrations was used as seeds to control the dimension of Zn crystals from the nanometer (30 nm) to micrometer scale (2 mu m). Depending on heat-treatment temperature, different morphology was developed. In the temperature range of 200-300 degrees C, a compact polygon prismatic Zn structure was formed. However, in a high temperature range of 300-400 degrees C, polygon prismatic Zn with hollow structure was observed. After oxidation treatment, the ZnO surface layer can be developed on the Zn nanocrystals to form ZnO-Zn core-shell structure as evidenced from PL measurement. These formed ZnO-Zn nano- and micro-crystals can be further used as building blocks to assemble two- or three-dimensional photonic crystals.
Growth and characterization of Zn-ZnO core-shell polygon prismatic nanocrystals on Si
(2004-09-01)
Lin, CC
;
Liu, KH
;
Chen, SY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Zn precursor synthesized from Zn(ClO4)(2) Solution was used as nucleation seeds for the growth of Zn polygon prismatic nanocrystals on silicon via a thermal vapor transport at low temperatures of 150-400degreesC (substrate) in Ar atmosphere. Depending on different reaction temperature and atmosphere, Zn-ZnO core-shell polygon prismatic nanocrystals with a dimension from nanometer to micrometer can be developed as evidenced from high-resolution transmission electron microscopy and auger nanoprobe electron spectroscopy analysis. The Zn-ZnO polygon prismatic structure shows weak UV emission and strong deep-level emission. However, photoluminescence properties and crystallization of Zn-ZnO prismatic nanocrystals could be improved by suitable post-treatment. (C) 2004 Elsevier B.V. All rights reserved.
Growth and physical characterization of polygon prismatic hollow Zn-ZnO crystals
(2005-03-01)
Liu, KH
;
Lin, CC
;
Chen, SY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A hierarchical polygon prismatic Zn-ZnO core-shell structure was grown on silicon by combining liquid-solution colloidals together with the vapor-gas growth process. Zn colloidals with a diameter of 5-10 nm synthesized from Zn(ClO4)(2) precursor solution were used as nucleation seeds for the growth of Zn polygon prismatic nanocrystals. Depending on carrier gas and annealing conditions, the polygon prismatic Zn crystals having morphology from hollow to dense configuration can be manipulated. Moreover, after prolonged thermal treatment at 300-400 degrees C, polygon prismatic hollow ZnO-Zn crystals with a dimension from nanometer to micrometer can be obtained. The room-temperature photoluminescence spectra show that the hollow ZnO-Zn crystals have a weak ultraviolet (UV) emission at 380 nm and a strong green emission at 500 nm. However, the intensity of the UV emission can be improved by postannealing the Zn-ZnO core-shell structure in an oxygen atmosphere to form hollow ZnO crystals.