Controlled catalytic growth and characterization of zinc oxide nanopillars on a-plane sapphire
Controlled catalytic growth and characterization of zinc oxide nanopillars on a-plane sapphire
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DOI：
10.1063/1.2710295
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发表时间：
2007-03-01
影响因子：
3.2
通讯作者：
Thonke, K.
中科院分区：
文献类型：
--
作者：
Reiser, A.;Ladenburger, A.;Thonke, K.
使用气-液-固（VLS）技术，我们已经生长良好的对齐的纳米柱上[1120]-蓝宝石（a-平面）衬底在大气压下在水平管式炉采用不同尺寸和密度的金催化剂种子。这是本工作的目的是找到实验条件（源和模板温度，温度梯度，载气流量，金簇的大小和密度）下发生的纳米柱的控制催化生长。预期VLS方法导致氧化锌（ZnO）柱直径与金催化剂簇尺寸的相关性。事实上，这是正确的，除了非常小的金簇。在我们的实验中获得的a面蓝宝石柱直径的最小值约为20 nm，这显然代表了一个一般的限制。结构表征依赖于高分辨率X射线衍射、原子力显微镜和高分辨率扫描电子显微镜。电子特性是通过拉曼和标准发光测量与大面积（约1毫米（2））激发。特别是，我们还研究了个人纳米柱的空间高分辨阴极发光光谱。我们发现，发光平均在大面积可以占主导地位的功能，这是不典型的形状良好的支柱，但来自不规则的ZnO生长区域。(c)2007年，美国物理学会。
Using the vapor-liquid-solid (VLS) technique, we have grown well-aligned nanopillars on [1120]-sapphire (a-plane) substrates at atmospheric pressure in a horizontal tube furnace employing gold catalyst seeds of different sizes and densities. It was the aim of the present work to find experimental conditions (source and template temperatures, temperature gradients, carrier gas flow, gold cluster size and density) under which controlled catalytic growth of nanopillars takes place. The VLS process is expected to result in a correlation of the zinc oxide (ZnO) pillar diameters with the gold catalyst cluster size. This is indeed found to hold true except for very small gold clusters. A minimum value of the pillar diameter of about 20 nm on a-plane sapphire is obtained in our experiments, which apparently represents a general limit. Structure characterization relies on high-resolution x-ray diffraction, atomic force microscopy, and high-resolution scanning electron microscopy. Electronic characterization is done by Raman and standard luminescence measurements with large area (approximate to 1 mm(2)) excitation. In particular, we have also studied individual nanopillars by spatially highly resolved cathodoluminescence spectroscopy. We find that luminescence averaged over large areas can be dominated by features which are not typical for well-shaped pillars but come from regions of irregular ZnO growth. (c) 2007 American Institute of Physics.