期刊
APPLIED SURFACE SCIENCE
卷 257, 期 8, 页码 3291-3297出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apsusc.2010.11.005
关键词
ZnO nanowires; Au catalyst; VLS; Field emission
类别
资金
- Research and Technology Council of Sharif University of Technology
The ZnO nanowires have been synthesized using vapor-liquid-solid (VLS) process on Au catalyst thin film deposited on different substrates including Si(1 0 0), epi-Si(1 0 0), quartz and alumina. The influence of surface roughness of different substrates and two different environments (Ar + H-2 and N-2) on formation of ZnO nanostructures was investigated. According to AFM observations, the degree of surface roughness of the different substrates is an important factor to form Au islands for growing ZnO nanostructures (nanowires and nanobelts) with different diameters and lengths. Si substrate (without epi-taxy layer) was found that is the best substrate among Si (with epi-taxy layer), alumina and quartz, for the growth of ZnO nanowires with the uniformly small diameter. Scanning electron microscopy (SEM) reveals that different nanostructures including nanobelts, nanowires and microplates have been synthesized depending on types of substrates and gas flow. Observation by transmission electron microscopy (TEM) reveals that the nanostructures are grown by VLS mechanism. The field emission properties of ZnO nanowires grown on the Si(1 0 0) substrate, in various vacuum gaps, were characterized in a UHV chamber at room temperature. Field emission (FE) characterization shows that the turn-on field and the field enhancement factor (beta) decrease and increases, respectively, when the vacuum gap (d) increase from 100 to 300 mu m. The turn-on emission field and the enhancement factor of ZnO nanowires are found 10 V/mu m and 1183 at the vacuum gap of 300 mu m. (C) 2010 Elsevier B.V. All rights reserved.
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