半導體硫化鋅奈米結構之合成、結構鑑定及特性之研究

Semiconducting ZnS-based Nanostructures: Synthesis, Characterization, and Properties

呂明諺(Ming-Yen Lu)

指導教授 ： 陳力俊

國立清華大學/工學院/材料科學工程學系/博士(2009年)

https://doi.org/10.6843/NTHU.2009.00035

摘要

Synthesis, characterizations, and physical properties of ZnS-based nanostructures have been investigated. Zinc sulfide has attracted intensive research effort in recent years, due to its unique properties and versatile applications. The design and control over size and morphology of ZnS nanostructures is of current interest. It is important to exploit both the wiring and device elements in architectures for functional nanosystems properties and new phenomena arising from heterostructures. The possible advanced applications of these structures are also proposed.
Self-assembled ZnS nanocombs with ZnO sheath have been grown using a thermal evaporation under controlled conditions. The growth directions of ZnS stems and nanotooth were analyzed to be along [2-1-10] and [0001], respectively. The asymmetric growth of ZnS tooth is due to the polar surface of wurtzite materials, the tooth are grown only at (0001) Zn polar surface, which is relatively active, compared to (0001) S polar surface. ZnO sheath was formed during the cooling-down stage with the residual O2. The non-metal-catalyst approach has the advantage of producing high purity nanostructures. These nanoteeth arrays might find applications in one-dimensional photonic crystals and the investigation of nonlinear collective effects.
The growth of CoxZn1-xS nanowires (NWs) was carried out using a one-step thermal evaporation method. The doping levels of cobalt in ZnS nanowires can be modulated by different amount of doping sources. Both Co signals taken by EDS and planar defects in nanowires imply that the Co ions incorporate within the ZnS nanowires by means of systematical substitution for Zn ions. The magnetism of the nanowires was maintained at room temperature and the saturated magnetization increased with cobalt contents. Electron transport measurements of single nanowire devices showed not only linear relationship, which represents Ohmic contacts of nanowire devices, but also tunable conductivities by doping concentration.
Quasi-vertical ZnS nanostructures doped with Ga (Ga-doped ZnS nanowalls) have been synthesized in high yield from mixed powders in the vacuum furnace. Ga-doped ZnS nanowalls were grown vertically on the substrate with the size in the range of several microns and the thickness down to ~15 nm and have very rough edges. Due to high surface area and distinctive morphology of Ga-doped ZnS nanowalls, the photocatalytic activity and the photoresponse show superior properties. The increasing conductivities of Ga-doped ZnS MSM Schottky photodetectors under light illumination are owing to the presence of oxygen on Ga-doped ZnS surface and the lowering of Schottky barrier height.
Vertically aligned ZnO-ZnS heterojunction nanowire arrays were synthesized for the first time by thermal evaporation in a tube furnace under controlled conditions. Both ZnO and ZnS are of wurtize structure, and the axial heterojunctions are formed by epitaxial growth of ZnO on ZnS with an orientation relationship of [0001]ZnO // [0001]ZnS. Vertical ZnS NW arrays have been obtained by selectively etching of ZnO-ZnS NW arrays. Cathodeluminescence measurements of ZnO-ZnS NW arrays and ZnS NW arrays show emissions at 509 and 547 nm, respectively. Both types of aligned NW arrays have been applied to convert mechanical energy into electricity when they are deflected by a conductive AFM tip in contact mode. The received results are explained by the mechanism proposed for nanogenerator.

關鍵字

硫化鋅 ； 奈米結構

並列摘要

無資料

並列關鍵字

Zinc Sulfide ； nanostructures

參考文獻

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