ZnO Nanorods Grown on Heterogenous Ag Seed Layers for Single-Cell Fluorescence Bioassays

ABSTRACTControlled ZnO nanostructures were grown on a flexible substrate for the future development of smart sensing tags. Thermolysis-assisted chemical solution deposition was used to grow ZnO nanorods at 85°C from 0.01mol of Zinc nitrate hexahydrate and HMT (Hexamethyltetramine) solution. To promote and modulate the ZnO nanorods, R.F. sputtered ZnO seed layers were deposited on polyimide substrates at various film thicknesses in the range of 8 to 160 nm. The optimum processing conditions to fabricate ZnO nanostructures have been investigated to examine the growth behaviors and to correlate the process parameters with the morphological characteristics. When the ethanol gas sensitivities were measured at different thickness of ZnO seed layers before growing ZnO nanorods, the highest sensitivity was obtained at 40 nm thick ZnO film at 300°C where the film thickness is similar to the Debye length. When ZnO nanorods were grown on such a ZnO seed layer, the sensitivities were more heavily influenced by the ZnO nanostructures rather than the thickness of the seed layer probably due to the dominant proportion of carrier density involved with the gas absorption.

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The Role of ALD-ZnO Seed Layers in the Growth of ZnO Nanorods for Hydrogen Sensing

Micromachines ◽

10.3390/mi10070491 ◽

2019 ◽

Vol 10 (7) ◽

pp. 491 ◽

Cited By ~ 3

Author(s):

Yangming Lu ◽

Chiafen Hsieh ◽

Guanci Su

Keyword(s):

Zinc Oxide ◽

Surface Area ◽

Gas Sensing ◽

Zno Nanorods ◽

Clean Energy ◽

Hydrogen Sensor ◽

Zno Films ◽

Hydrogen Sensing ◽

Highly Sensitive ◽

Seed Layers

Hydrogen is one of the most important clean energy sources of the future. Because of its flammability, explosiveness, and flammability, it is important to develop a highly sensitive hydrogen sensor. Among many gas sensing materials, zinc oxide has excellent sensing properties and is therefore attracting attention. Effectively reducing the resistance of sensing materials and increasing the surface area of materials is an important issue to increase the sensitivity of gas sensing. Zinc oxide seed layers were prepared by atomic layer deposition (ALD) to facilitate the subsequent hydrothermal growth of ZnO nanorods. The nanorods are used as highly sensitive materials for sensing hydrogen due to their inherent properties as oxide semiconductors and their very high surface areas. The low resistance value of ALD-ZnO helps to transport electrons when sensing hydrogen gas and improves the sensitivity of hydrogen sensors. The large surface area of ZnO nanorods also provides lots of sites of gas adsorption which also increases the sensitivity of the hydrogen sensor. Our experimental results show that perfect crystallinity helped to reduce the electrical resistance of ALD-ZnO films. High areal nucleation density and sufficient inter-rod space were determining factors for efficient hydrogen sensing. The sensitivity increased with increasing hydrogen temperature, from 1.03 at 225 °C, to 1.32 at 380 °C after sensing 100 s in 10,000 ppm of hydrogen. We discuss in detail the properties of electrical conductivity, point defects, and crystal quality of ALD-ZnO films and their probable effects on the sensitivity of hydrogen sensing.

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Seedless Hydrothermal Growth of ZnO Nanorods as a Promising Route for Flexible Tactile Sensors

Nanomaterials ◽

10.3390/nano10050977 ◽

2020 ◽

Vol 10 (5) ◽

pp. 977

Author(s):

Ilaria Cesini ◽

Magdalena Kowalczyk ◽

Alessandro Lucantonio ◽

Giacomo D’Alesio ◽

Pramod Kumar ◽

...

Keyword(s):

Finite Element ◽

Aspect Ratio ◽

Growth Temperature ◽

Zno Nanorods ◽

Tactile Sensor ◽

Hydrothermal Growth ◽

Tactile Sensors ◽

Polyimide Substrate ◽

Vertically Aligned ◽

Seed Layers

Hydrothermal growth of ZnO nanorods has been widely used for the development of tactile sensors, with the aid of ZnO seed layers, favoring the growth of dense and vertically aligned nanorods. However, seed layers represent an additional fabrication step in the sensor design. In this study, a seedless hydrothermal growth of ZnO nanorods was carried out on Au-coated Si and polyimide substrates. The effects of both the Au morphology and the growth temperature on the characteristics of the nanorods were investigated, finding that smaller Au grains produced tilted rods, while larger grains provided vertical rods. Highly dense and high-aspect-ratio nanorods with hexagonal prismatic shape were obtained at 75 °C and 85 °C, while pyramid-like rods were grown when the temperature was set to 95 °C. Finite-element simulations demonstrated that prismatic rods produce higher voltage responses than the pyramid-shaped ones. A tactile sensor, with an active area of 1 cm2, was fabricated on flexible polyimide substrate and embedding the nanorods forest in a polydimethylsiloxane matrix as a separation layer between the bottom and the top Au electrodes. The prototype showed clear responses upon applied loads of 2–4 N and vibrations over frequencies in the range of 20–800 Hz.

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Controllable growth of ZnO nanorods by seed layers annealing using hydrothermal method

Materials Letters ◽

10.1016/j.matlet.2013.06.100 ◽

2013 ◽

Vol 108 ◽

pp. 46-49 ◽

Cited By ~ 15

Author(s):

Fenglin Xian ◽

Wangfeng Bai ◽

Linhua Xu ◽

Xiaoxiong Wang ◽

Xiangyin Li

Keyword(s):

Hydrothermal Method ◽

Zno Nanorods ◽

Controllable Growth ◽

Seed Layers

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Magnesium Content Ratio Effects of MgxZn1–xO Seed Layers on Structural and Optical Properties of ZnO Nanorods

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2012.6236 ◽

2012 ◽

Vol 12 (7) ◽

pp. 5386-5391

Author(s):

Min Su Kim ◽

Do Yeob Kim ◽

Soaram Kim ◽

Giwoong Nam ◽

Sung-O Kim ◽

...

Keyword(s):

Optical Properties ◽

Zno Nanorods ◽

Magnesium Content ◽

Structural And Optical Properties ◽

Content Ratio ◽

Seed Layers

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Low-temperature hydrothermal growth of ZnO nanorods on sol–gel prepared ZnO seed layers: Optimal growth conditions

Thin Solid Films ◽

10.1016/j.tsf.2012.10.007 ◽

2012 ◽

Vol 524 ◽

pp. 144-150 ◽

Cited By ~ 27

Author(s):

Hyeon Jin Jung ◽

Seulki Lee ◽

Yiseul Yu ◽

Seung Min Hong ◽

Hyun Chul Choi ◽

...

Keyword(s):

Low Temperature ◽

Sol Gel ◽

Zno Nanorods ◽

Optimal Growth ◽

Growth Conditions ◽

Hydrothermal Growth ◽

Seed Layers

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Thermal annealing effects of MBE-seed-layers on properties of ZnO nanorods grown by hydrothermal method

Journal of Crystal Growth ◽

10.1016/j.jcrysgro.2011.01.096 ◽

2011 ◽

Vol 326 (1) ◽

pp. 195-199 ◽

Cited By ~ 11

Author(s):

Min Su Kim ◽

Kwang Gug Yim ◽

Hyun Young Choi ◽

Min Young Cho ◽

Ghun Sik Kim ◽

...

Keyword(s):

Hydrothermal Method ◽

Thermal Annealing ◽

Zno Nanorods ◽

Annealing Effects ◽

Seed Layers

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Influence of Al, Ta Doped ZnO Seed Layer on the Structure, Morphology and Optical Properties of ZnO Nanorods

Current Smart Materials ◽

10.2174/2405465804666190326150628 ◽

2019 ◽

Vol 4 (1) ◽

pp. 45-58

Author(s):

S. Mageswari ◽

Balan Palanivel

Keyword(s):

Zinc Oxide ◽

Optical Properties ◽

Band Gap ◽

Seed Layer ◽

Hexagonal Phase ◽

Zno Nanorods ◽

Oxide Material ◽

Vertically Aligned ◽

Doped Zno ◽

Seed Layers

Background: Zinc oxide (ZnO) is one of the most attractive II-VI semiconductor oxide material, because of its direct wide band gap (3.37 eV) and large binding energy (60 meV). Zinc oxide (ZnO) is a promising semiconductor due to its optimised optical properties. Among semiconductor nanostructures, the vertically aligned one-dimensional ZnO nanorods are very important for nano device application. Methods: Vertically aligned ZnO nanorod arrays were grown on ZnO, aluminum doped ZnO (ZnO:Al), tantalum doped ZnO (ZnO:Ta) and aluminum and tantalum co-doped ZnO (ZnO:Al,Ta) seed layer by hydrothermal method. Results: The X-Ray Diffraction (XRD) investigation indicated the presence of hexagonal phase for the both seed layers and nanorods. The Scanning Electron Microscope (SEM) images of ZnO and doped ZnO seed layer thin-films show spherical shaped nanograins organized into wave like morphology. The optical absorption spectra revealed shift in absorption edge towards the shorter wavelength (blue shifted) for ZnO nanorods grown on ZnO:Al, ZnO:Ta and ZnO:Al,Ta seed layer compared to ZnO nanorods grown on ZnO seed layer. Conclusion: The increase in band gap value for the ZnO nanorods grown on doped ZnO seed layers due to the decrease in crystallite size and lattice constant as evidenced from XRD analysis. The unique property of Al, Ta doped ZnO can be used to fabricate nano-optoelectronic devices and photovoltaic devices, due to their improved optical properties.

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Effect of ZnO Seed Layer with Various Concentrations of Precursor on the Growth of ZnO Nanostructures

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.675-676.237 ◽

2016 ◽

Vol 675-676 ◽

pp. 237-240

Author(s):

Nontakoch Siriphongsapak ◽

Somyod Denchicharoen ◽

Pichet Limsuwan

Keyword(s):

Zinc Acetate ◽

Seed Layer ◽

Zinc Acetate Dihydrate ◽

Zno Nanorods ◽

Crystallographic Structure ◽

Nitrate Hexahydrate ◽

X Rays ◽

Zno Nanostructures ◽

Acetate Dihydrate ◽

Seed Layers

In this work, Zinc oxide (ZnO) thin films were deposited on silicon and glass substrates using spin-coating method with different concentrations of precursor (zinc acetate dihydrate) and stabilizer (monoethanolamine). The concentrations of zinc acetate dihydrate and monoethanolamine in isopropanol were varied from 6 mM to 500 mM. Subsequently, the substrate with ZnO thin film as a seed layer was used to grow ZnO nanostructures by hydrothermal process with the same concentration of precursor (zinc nitrate hexahydrate), temperature, and time for each growth. The samples were characterized by field-emission scanning electron microscopy (FESEM), X-rays diffractometer (XRD), and UV-visible spectrophotometer (UV-vis) to study morphology, crystallographic structure, and optical property, respectively. The results showed that particle size, crystallinity, and transmittance of seed layers were changed with increasing concentrations of spin-coated precursor. Furthermore, the nanostructures were found that higher precursor concentration of seed layers affected the formation of ZnO nanorods to be nanosheets.

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