Abstract
Vertically aligned, high‐density ZnO nanowires (NWs) were grown for the first time on c‐plane sapphire using binary alloys of Ni/Au or Cu/Au as the catalyst. The growth was performed under argon gas flow and involved the vapor‐liquid‐solid (VLS) growth process. We have investigated various ratios of catalyst components for the NWs growth and results indicate that very thin adhesion layers of Ni or Cu deposited prior to the Au layer are not deleterious to the ZnO NW array growth. Significant improvement of the Au adhesion on the substrate was noted, opening the potential for direct catalyst patterning of Au and subsequent NW array growth. Additionally, we found that an increase of in thickness of the Cu adhesion layer results in the simultaneous growth of NWs and nanoplates (NPs), indicating that in this case the growth involves both the VLS and vapor‐solid (VS) growth mechanisms. Energy dispersive X‐ray spectroscopy (EDX) and surface‐enhanced Raman scattering (SERS) studies were also performed to characterize the resulting ZnO NW arrays, indicating that the NWs grown using a thin adhesion layer of Ni or Cu under the Au show comparable SERS enhancement to those of the pure Au‐catalyzed NWs.
Highlights
One-dimensional zinc oxide (ZnO) nanowires (NWs) have been attracting much attention because they can be used to design novel nanoscale devices due to their wide band gap, high mechanical stability, and high isoelectric point [1,2,3,4,5,6,7,8,9,10,11,12,13]
A LEO SUPRA 55 scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) capability was used to investigate the topographies and the chemical compositions of the NWs and the alloy tip formed during the growth process
The representative scanning electron microscope (SEM) images of bi-layers of 1 nm Ni/5 nm Au, 1 nm Cu/5 nm Au, and pure Au-catalyzed ZnO NWs grown on c-sapphire are shown in Figures 1(a), 1(b), and 1(c), respectively
Summary
One-dimensional zinc oxide (ZnO) nanowires (NWs) have been attracting much attention because they can be used to design novel nanoscale devices due to their wide band gap, high mechanical stability, and high isoelectric point [1,2,3,4,5,6,7,8,9,10,11,12,13]. One of the well-established methods to grow nanowires is the vapor-liquid-solid (VLS) growth process, in which Au is used as the catalyst [16, 17]. Vertical ZnO nanowire (NWs) arrays have been grown using pure Au catalyst [7], the use of these ZnO NW arrays in the design and fabrication of new plasmonic structures is limited due to the poor adhesion of Au on the required sapphire or GaN substrates, which is well known. We have investigated the use of adhesion layers of different metals, including Cu, Ni, Cr, Ti and their bi-layers with Au, in order to grow vertically aligned ZnO NWs on c-sapphire, which would be amenable to nanopatterning and further device fabrication. Additional characterization techniques showed that the NWs grown using certain thin adhesion layers did not change their optical or structural properties, a necessary condition for future plasmonic device designs and fabrication
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
