Abstract
Zinc oxide/carbon nanotube (ZnO/CNTs) nanocomposites are developed on gold (Au)-coated unpolished Si p-type (100) substrates with 2, 4, 6, 8, and 10 nm thicknesses by vapor–liquid–solid method. One set of Au-coated Si substrates are annealed to develop Si–Au samples for better nucleation. XRD, FE-SEM, Raman, and photoluminescence spectroscopic characterizations are used to study structural, morphological, and optical properties on annealed and unannealed catalyst layers with various Au thickness samples. In XRD results, the ZnO/CNT nanocomposites are observed with higher crystallinity and purity of phase. FE-SEM images showed variety of nanostructures with variation in morphologies with respect to Au thickness in annealed and unannealed samples. Clear indication of high defect concentrations and high crystallinity is observed in Raman spectra. It is observed in PL spectra that preferred peak orientation with shift ∼4 nm in the unannealed Au layer and ∼9 nm in annealed Au layer samples exhibited formation of ZnO/CNT nanocomposites. Efficient sensing is observed in the 6-nm thickness Au layer in the unannealed sample. Annealed Au-coated Si samples at 8 and 10 nm thicknesses showed efficient UV sensing with quick response and recovery time.
Highlights
Zinc oxide (ZnO) nanostructures have a wide range of operating temperature, stability, and flexibility, which make them a good candidate for sensing applications (Sinha et al, 2006; Yin et al, 2013)
The method used in this study develops a direct link between the Carbon nanotubes (CNTs) and ZnO nanostructures during synthesis
The wurtzite structure of ZnO and high crystallinity was confirmed by XRD results with sharp ZnO peaks
Summary
ZnO nanostructures have a wide range of operating temperature, stability, and flexibility, which make them a good candidate for sensing applications (Sinha et al, 2006; Yin et al, 2013). CNTs have drastically different mechanical, electrical, optical, and electromechanical properties, which give researchers the urge to experiment with them and discover their applications at the nanoscale They provide highly selective, responsive, cheap, and sensitive sensors depending upon their structures (JohanssonWacaser et al, 2006; Wang et al, 2008). Compared to CNTs, ZnO nanostructures show enhanced divergent light emission with optical transition and mechanical properties (Wang and Geng, 2005) These changes in properties give insights about next-generation applications in optoelectronic and electronic fields such as batteries, solar cells, supercapacitors, and sensors. This low level emission increases the chances of electron-hole recombination Nanocomposites of such ZnO nanostructures and CNTs show stability-enhanced mechanical, electrical, magnetic, and optical behaviors which allow these nanocomposite potential applications (Wang, 2009), such as photocatalysts (Afrin et al, 2013), nanoelectronics, nanodevices, and sensors. Very encouraging results with high sensitivity and quick response time of UV sensors are reported in this study
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