Heteroepitaxial Growth and Spatially Resolved Cathodoluminescence of ZnO/MgZnO Coaxial Nanorod Arrays
Heteroepitaxial Growth and Spatially Resolved Cathodoluminescence of ZnO/MgZnO Coaxial Nanorod Arrays
复制标题
ZnO/MgZnO 同轴纳米棒阵列的异质外延生长和空间分辨阴极发光
DOI：
10.1021/jp102395t
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发表时间：
2010-09
影响因子：
3.7
通讯作者：
Hark S.
中科院分区：
文献类型：
--
作者：
Liu W.;Liang Y.;Xu H.;Wang L.;Zhang X.;Liu Y.;Hark S.
采用水热合成结合脉冲激光沉积的方法，在GaN衬底上外延生长了垂直排列的单晶ZnO/MgZnO同轴纳米棒阵列。通过Z衬度扫描透射电子显微镜和线扫描成分分析证实了具有高质量界面和相干外延关系的定义明确的核/壳异质结构。有趣的是，由于沉积过程中的阴影效应，MgZnO壳层厚度从纳米棒的尖端到基部逐渐减小。不均匀的涂层使我们能够研究单个纳米棒上的载流子限制和表面钝化效应。空间分辨阴极发光测量表明，ZnO核的带边发射强度是可变的沿着其长度，并强烈依赖于壳的厚度。一个模型，其中包括载流子隧穿，表面陷阱，和辐射/非辐射复合过程，开发来理解这种现象…
Vertically aligned, single-crystalline ZnO/MgZnO coaxial nanorod arrays were epitaxially grown on GaN substrates by hydrothermal synthesis combined with pulsed laser deposition. Well-defined core/shell heterostructures with high-quality interfaces and coherent epitaxial relationship were confirmed by Z-contrast scanning transmission electron microscopy and line-scan compositional analyses. It is interesting to note that the MgZnO shell thickness gradually decreases from the tip to the base of the nanorods, due to a shadow effect during the deposition. The nonuniform coating allows us to study the carrier confinement and surface passivation effects on a single nanorod. Spatially resolved cathodoluminescence measurements reveal that the band-edge emission intensity of ZnO cores is variable along their length, and depends strongly on the shell thickness. A model, which involves carrier tunneling, surface trapping, and radiative/nonradiative recombination processes, was developed to understand this phenomenon...