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The effect of substrate surface roughness on ZnO nanostructures growth

Roozbehi, M ; Sharif University of Technology | 2011

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  1. Type of Document: Article
  2. DOI: 10.1016/j.apsusc.2010.11.005
  3. Publisher: 2011
  4. Abstract:
  5. 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 + H2 and N2) 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 (β) decrease and increases, respectively, when the vacuum gap (d) increase from 100 to 300 μm. The turn-on emission field and the enhancement factor of ZnO nanowires are found 10 V/μm and 1183 at the vacuum gap of 300 μm
  6. Keywords:
  7. AFM observation ; AU catalysts ; Au islands ; Different substrates ; Enhancement factor ; Field emission property ; Field enhancement factor ; Gas flows ; Microplates ; Room temperature ; SEM ; Si substrates ; Si(1 0 0) ; Small-diameter ; Substrate surface ; TEM ; Turn-on field ; UHV chambers ; Vacuum gap ; Vapor-liquid-solid process ; VLS ; VLS mechanism ; ZnO nanostructures ; ZnO nanowires ; Catalysts ; Field emission ; Gold ; Gold coatings ; Metal analysis ; Nanobelts ; Nanowires ; Quartz ; Scanning electron microscopy ; Semiconducting silicon compounds ; Silicon ; Surface properties ; Surface roughness ; Transmission electron microscopy ; Vacuum ; Zinc oxide ; Substrates
  8. Source: Applied Surface Science ; Volume 257, Issue 8 , February , 2011 , Pages 3291-3297 ; 01694332 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S016943321001528X