期刊
JOURNAL OF PHYSICAL CHEMISTRY C
卷 114, 期 39, 页码 16148-16152出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp102395t
关键词
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资金
- National Natural Science Foundation of China [50725205, 60907016]
- Fund from Jilin Province [20100339, 20080102, FH0009]
- NENU [NENU-STC08001]
- Research Grants Council of the Hong Kong Special Administrative Region, China [411807, 417507]
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. However, a high-temperature thermal treatment may lead to the stress relaxation and the formation of interfacial defects, and enhance the interdiffusion of interfacial atoms. These degrade the optical quality of coaxial nanorods.
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