Department of Chemistry, University of Liverpool, Liverpool, UK.
Nanotechnology. 2010 Jan 29;21(4):045701. doi: 10.1088/0957-4484/21/4/045701. Epub 2009 Dec 10.
The optical properties of zinc oxide nanowires are critically influenced by the growth process. Herein, we describe a metal-organic chemical vapour deposition (MOCVD) process for the growth of ZnO nanowires with improved optical properties. A tetrahydrofuran adduct is used to control the reactivity of dimethylzinc to enable this. Vertically aligned zinc oxide nanowires have been grown on Si(111) substrates by liquid injection MOCVD, using a solution of [Me(2)Zn(tetrahydrofuran)] in the presence of oxygen. The ZnO morphology becomes nanowire-like in a narrow temperature range centred about 500 degrees C. Above and below this temperature range, the ZnO is deposited in the form of polycrystalline films. The ZnO nanowires grow from a polycrystalline nucleation layer, with the (0002) c-axis parallel to the Si[111] substrate orientation. High-resolution electron microscopy reveals a highly crystalline nanowire microstructure. Resonance enhanced ultraviolet Raman spectroscopy shows that the ratio of first- and second-order longitudinal optic modes is commensurate with electron-phonon coupling effects observed previously in ZnO nanostructures. Photoluminescence exhibits intense near band-edge emission with a full width at half-maximum of 110 meV at room temperature and shows negligible defect-related visible emission.
氧化锌纳米线的光学性质受到生长过程的极大影响。在此，我们描述了一种金属有机化学气相沉积（MOCVD）工艺，用于生长具有改善的光学性质的 ZnO 纳米线。使用四氢呋喃加合物来控制二甲基锌的反应性，从而实现这一点。使用[Me（2）Zn（四氢呋喃）]在氧气存在下的溶液，通过液体注射 MOCVD 在 Si（111）衬底上生长垂直排列的氧化锌纳米线。在约 500°C 的窄温度范围内，ZnO 形态变得类似于纳米线。在该温度范围之上和之下，ZnO 以多晶薄膜的形式沉积。ZnO 纳米线从多晶形核层生长，（0002）c 轴与 Si[111]衬底取向平行。高分辨率电子显微镜显示出高度结晶的纳米线微观结构。共振增强紫外拉曼光谱显示，一阶和二阶纵光学模式的比值与先前在 ZnO 纳米结构中观察到的电子-声子耦合效应相符。室温下光致发光显示出强烈的近带边发射，半最大值全宽为 110 meV，并且显示出可忽略的与缺陷相关的可见发射。
