scholarly journals Synthesis and Characterization of c-Axis Oriented Zinc Oxide Thin Film and Its Use for the Subsequent Hydrothermal Growth of Zinc Oxide Nanorods

MRS Advances ◽  
2019 ◽  
Vol 4 (16) ◽  
pp. 921-928
Author(s):  
S.F.U. Farhad ◽  
N.I. Tanvir ◽  
M.S. Bashar ◽  
M. Sultana
Keyword(s):  
Zinc Oxide ◽  
Band Gap ◽  
Seed Layer ◽  
Optical Band Gap ◽  
Zno Nanorods ◽  
Zinc Oxide Nanorods ◽  
Oxide Thin Film ◽  
Yellow Emission ◽  
Zno Films ◽  
Seed Layers

ABSTRACTOriented ZnO seed layers were deposited by three different techniques, namely, simple drop casting (DC), sol-gel derived dip coating (DPC) and spin coating of ball-milled ZnO powder solution(BMD) for the subsequent growth of vertically aligned ZnO nanorods along the substrate normal. X-ray diffraction (XRD) analyses revealed that ZnO(DC) seed layer exhibit the highest preferential c-axis texturing among the ZnO seed layers synthesized by different techniques. The Scanning Electron Microscopy (SEM) analysis evident that the morphology of ZnO seed layer surface is compact and coherently carpets the underlying substrate. ZnO nanorods(NRs) were then grown by hydrothermal method atop the ZnO seeded and non-seeded substrates grown by different techniques to elucidate the best ZnO seed layer promoting well-aligned ZnO Nanorods. The presence of c-axis oriented ZnO(DC) seeding layers was found to significantly affect the surface morphology and crystallographic orientation of the resultant ZnO NRs films. The optical band gap of ZnO(DC) seed and ZnO NRs were estimated to be 3.30 eV and in the range of 3.18 – 3.25 eV respectively by using UV-VIS-NIR diffuse reflection spectroscopy. The room temperature photoluminescence analyses revealed that nanostructured ZnO films exhibit a sharp near-band-edge luminescence peak at ∼380 nm consistent with the estimated optical band gap and the ZnO nanorod arrays are notably free from defect-related green-yellow emission peaks.

scholarly journals Facile synthesis of oriented zinc oxide seed layer for the hydrothermal growth of zinc oxide nanorods

2018 ◽  
Vol 53 (4) ◽  
pp. 233-244 ◽  
Author(s):  
SFU Farhad ◽  
NI Tanvir ◽  
MS Bashar ◽  
MS Hossain ◽  
M Sultana ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Seed Layer ◽  
Room Temperature ◽  
Zinc Acetate Dihydrate ◽  
Zno Nanorods ◽  
Zinc Oxide Nanorods ◽  
Yellow Emission ◽  
Zno Films ◽  
Near Band Edge ◽  
Seed Layers

Oriented zine oxide (ZnO) seed layers were deposited by simple drop casting of zinc acetate dihydrate (ZAD) solution on glass substrates at room temperature followed by a post-heat treatment at 250 oC. X-ray diffraction (XRD) analyses revealed that ZAD solutions with concentration 0.0025 – 0.0100 M produced amorphous type thin films, whereas 0.0200 M ZAD solutions produced ZnO seed layers with a preferential c-axis texturing.The Scanning Electron Microscopy (SEM) analyses evident that the morphology of ZnO seed layer surface is compact and coherently carpets the underlying glass substrate. ZnO nanorods were then grown by hydrothermal method atop the ZnO seeded and non-seeded substrates. The presence of ZnO seeding layers was found to be beneficial for growing ZnO NRs films vertically. The optical bandgap of ZnO seed and ZnO NR were estimated to be in the range of 3.40 – 3.95 eV and 3.20 – 3.25 eV respectively by using UV-VIS-NIR diffuse reflection spectroscopy. The room temperature photoluminescence analyses revealed that nanostructured ZnO films exhibit a sharp near-band-edge luminescence peak at ~380 nm consistent with the estimated optical band gap and the ZnO nanorod arrays are notably free from defect-related green-yellow emission peaks.Bangladesh J. Sci. Ind. Res.53(4), 233-244, 2018

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

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.

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

Micromachines ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 491 ◽  
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.

Growth of Arrayed ZnO Nanorods from Aqueous Solution at 60°C

2010 ◽  
Vol 123-125 ◽  
pp. 691-694
Author(s):  
Gang Qiang Yang ◽  
Xiao Ping Zou ◽  
Xiang Min Meng ◽  
Gong Qing Teng ◽  
Jin Cheng ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Zinc Oxide ◽  
Low Temperature ◽  
Zno Nanorods ◽  
The Other ◽  
Zinc Oxide Nanorods ◽  
Zno Films ◽  
Growth Mechanisms ◽  
Oxide Nanorods ◽  
Zno Particles

In this paper, zinc oxide nanorods were prepared on many different substrates in the aqueous solution without adding alkali solution at 60°C. A layer of ZnO particles as the seeds for the growth were not needed to be coated on the substrates beforehand. A higher uniform and denser packed array of hexagonal ZnO nanorods forms on the glass substrate than that on the other substrates in our experiments. This technique is applicable for the preparation and patterning of functional ZnO films at low temperature. The growth mechanisms of the as-synthesized ZnO nanorods were also proposed.

Effect of Structure Modifying Agents on the Structural, Morphological and Optical Features of Hydrothermally Grown ZnO

2020 ◽  
Vol 20 (5) ◽  
pp. 3265-3273 ◽  
Author(s):  
Rabia Ahson ◽  
Riaz Ahmad ◽  
Naveed Afzal ◽  
Farrukh Ehtesham Mubarik
Keyword(s):  
Zinc Oxide ◽  
Band Gap ◽  
Sodium Dodecyl Sulphate ◽  
Zinc Acetate ◽  
Zno Nanorods ◽  
Sodium Dodecyl ◽  
Trisodium Citrate ◽  
Hydrothermal Growth ◽  
Zno Films ◽  
Nitrate Hexahydrate

Morphology of Zinc Oxide (ZnO) is an important parameter to enhance the efficiency of optoelectronic devices. Morphology also plays a significant role in gas sensing properties of ZnO. In this research work, different morphologies of Zinc Oxide including nanorods, disks and flakes were obtained using Zinc Acetate, Sodium Dodecyl Sulphate and Trisodium Citrate as additives to a parent solution of Zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and Hexamethylenetetramine (HMTA, (CH2)6N4) for hydrothermal growth. Use of Zinc Acetate as an additive has been rarely reported. This work presents the ability of Zinc Acetate to transform the morphology of ZnO nanorods to nanoneedles. Furthermore, in this study addition of Sodium Dodecyl Sulphate and Trisodium Citrate to the parent solution has shown potential for growing continuous granular films by the low cost and low temperature hydrothermal technique. Variation in crystallite size and band gap values with increasing concentration of Zinc Acetate, Sodium Dodecyl Sulphate and Trisodium Sulphate has been studied. Films with crystallite sizes of 7.48 nm and 6.77 nm were achieved with 5 mM Sodium Dodecyl Sulphate and 5 mM Trisodium Citrate respectively. The band gap of films produced with 5 mM Sodium Dodecyl Sulphate and with 5 mM Trisodium Citrate were 3.43 eV and 3.45 eV respectively. Therefore hydrothermal growth with Sodium Dodecyl Sulphate or Trisodium Citrate is a potential technique for obtaining granular ZnO films.

scholarly journals Orange/Red Photoluminescence Enhancement Upon SF6 Plasma Treatment of Vertically Aligned ZnO Nanorods

Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 794 ◽  
Author(s):  
Amine Achour ◽  
Mohammad Islam ◽  
Sorin Vizireanu ◽  
Iftikhar Ahmad ◽  
Muhammad Aftab Akram ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Plasma Treatment ◽  
Zno Nanorods ◽  
Hydrothermal Process ◽  
Zinc Oxide Nanorods ◽  
Hydroxyl Group ◽  
Yellow Emission ◽  
X Ray ◽  
Vertically Aligned ◽  
Pl Emission

Although the origin and possible mechanisms for green and yellow emission from different zinc oxide (ZnO) forms have been extensively investigated, the same for red/orange PL emission from ZnO nanorods (nR) remains largely unaddressed. In this work, vertically aligned zinc oxide nanorods arrays (ZnO nR) were produced using hydrothermal process followed by plasma treatment in argon/sulfur hexafluoride (Ar/SF6) gas mixture for different time. The annealed samples were highly crystalline with ~45 nm crystallite size, (002) preferred orientation, and a relatively low strain value of 1.45 × 10−3, as determined from X-ray diffraction pattern. As compared to as-deposited ZnO nR, the plasma treatment under certain conditions demonstrated enhancement in the room temperature photoluminescence (PL) emission intensity, in the visible orange/red spectral regime, by a factor of 2. The PL intensity enhancement induced by SF6 plasma treatment may be attributed to surface chemistry modification as confirmed by X-ray photoelectron spectroscopy (XPS) studies. Several factors including presence of hydroxyl group on the ZnO surface, increased oxygen level in the ZnO lattice (OL), generation of F–OH and F–Zn bonds and passivation of surface states and bulk defects are considered to be active towards red/orange emission in the PL spectrum. The PL spectra were deconvoluted into component Gaussian sub-peaks representing transitions from conduction-band minimum (CBM) to oxygen interstitials (Oi) and CBM to oxygen vacancies (VO) with corresponding photon energies of 2.21 and 1.90 eV, respectively. The optimum plasma treatment route for ZnO nanostructures with resulting enhancement in the PL emission offers strong potential for photonic applications such as visible wavelength phosphors.

scholarly journals Rootlike Morphology of ZnO:Al Thin Film Deposited on Amorphous Glass Substrate by Sol-Gel Method

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Heri Sutanto ◽  
Sufwan Durri ◽  
Singgih Wibowo ◽  
Hady Hadiyanto ◽  
Eko Hidayanto
Keyword(s):  
Thin Films ◽  
Zinc Oxide ◽  
Band Gap ◽  
Glass Substrate ◽  
Optical Band Gap ◽  
Sol Gel ◽  
Spray Coating ◽  
Hexagonal Structure ◽  
Zno Films ◽  
Sem Images

Zinc oxide (ZnO) and aluminum doped zinc oxide (ZnO:Al) thin films have been deposited onto a glass substrate by sol-gel spray coating method at atmospheric pressure. X-ray diffractometer (XRD), scanning electron microscopy (SEM), and UV-Vis spectrophotometer have been used to characterize the films. XRD spectra indicated that all prepared thin films presented the wurtzite hexagonal structure. SEM images exhibited rootlike morphology on the surface of thin films and the shortest root diameter was about 0.219 μm. The UV-Vis absorption spectra exhibited the absorption edges that were slightly shifted to the lower wavelength. From this result, the incorporation of aluminum into the ZnO involved a slight increase in the optical band-gap of films. The optical bands of films were 3.102 eV, 3.115 eV, 3.118 eV, 3.115 eV, 3.109 eV, and 3.109 eV for ZnO, ZnO:Al 2%, ZnO:Al 4%, ZnO:Al 6%, ZnO:Al 8%, and ZnO:Al 10%, respectively. Increase of Al doping concentration in ZnO films contributed to the increase of their optical band-gap which can be explained by the Burstein-Moss effect.

Two-Photon Excited Ultraviolet Photoluminescence of Zinc Oxide Nanorods

2008 ◽  
Vol 8 (11) ◽  
pp. 5854-5857 ◽  
Author(s):  
Guangping Zhu ◽  
Chunxiang Xu ◽  
Jing Zhu ◽  
Changgui Lu ◽  
Yiping Cui ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Emission Band ◽  
Single Photon ◽  
Zno Nanorods ◽  
Zinc Oxide Nanorods ◽  
Excitation Wavelength ◽  
Photoluminescence Intensity ◽  
Vapor Phase Transport ◽  
Two Photon ◽  
Oxide Nanorods

High density zinc oxide nanorods with uniform size were synthesized on (100) silicon substrate by vapor-phase transport method. The scanning electron microscopy images reveal that the nanorods have an average diameter of about 400 nm. The X-ray diffraction pattern demonstrates the wurtzite crystalline structure of the ZnO nanorods growing along [0001] direction. The single-photon excited photoluminescence presents a strong ultraviolet emission band at 394 nm and a weak visible emission band at 600 nm. When the ZnO nanorods were respectively pumped by various wavelength lasers from 520 nm to 700 nm, two-photon excited ultraviolet photoluminescence was observed. The dependence of the two-photon excited photoluminescence intensity on the excitation wavelength and power was investigated in detail.

EFFECT OF PRE-HEATING AND SEED LAYER ON HYDROTHERMAL GROWTH AND OPTICAL PROPERTIES OF ZINC OXIDE NANORODS

2011 ◽  
Vol 10 (04n05) ◽  
pp. 845-849
Author(s):  
GAURAV SHUKLA ◽  
ALIKA KHARE
Keyword(s):  
Optical Properties ◽  
Seed Layer ◽  
Zno Nanorods ◽  
Pulsed Laser ◽  
Heating Time ◽  
Hydrothermal Growth ◽  
Zinc Oxide Nanorods ◽  
Growth Time ◽  
Oxide Nanorods ◽  
Reported Effect

Hydrothermal growth of highly c-axis oriented ZnO nanorods with high aspect ratio on pulsed laser deposited ZnO seed layer is reported. Effect of pre-heating time, growth time and seed layer on the structural, morphological and optical properties of ZnO nanorods is presented. The possible growth mechanism for ZnO nanorods is also discussed.

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