Electrochemical growth of ZnO nano-rods on polycrystalline Zn foil

Wong, Minhao; Berenov, A.; Qi, Xiaoding; Kappers, Menno J.; Barber, Z. H.; Illy, Benoit N.; Lockman, Zainovia; Ryan, Mary P.; MacManus‐Driscoll, Judith L.

doi:10.1088/0957-4484/14/9/306

Cited by 77 publications

(81 citation statements)

References 26 publications

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“…16 Recently, Kar et al prepared ZnO nanosheets (and nanowires) by a solvothermal route. 11 To date, despite numerous studies on electrochemical deposition of ZnO nanorods on various substrates, such as GaN, 17 indium-tin oxide (ITO), 13,18,19 SnO 2 , 20 ZnO films, 21 and Zn foils, 22,23 there are only a few reports on 2D ZnO nanostructures, including nanoplates, nanosheets and nanodisks. 21,[24][25][26] Furthermore, none of these reported 2D nanostructures is found to be vertically grown on the substrate.…”

Section: Introductionmentioning

confidence: 99%

Vertical Growth of Two-Dimensional Zinc Oxide Nanostructures on ITO-Coated Glass: Effects of Deposition Temperature and Deposition Time

2008

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Two-dimensional (2D) zinc oxide (ZnO) nanostructures of thickness 40-100 nm and length up to several micrometers are vertically grown on indium-tin oxide-coated glass substrates by using electrochemical deposition in the temperature range of 22-90°C. The deposition temperature is found to play a significant role in controlling the morphology of the nanostructures, from randomly oriented, poorly crystalline nanosheets at 22°C to well-aligned nanowalls with wurtzite structure at 70°C. At 80°C, nanowalls are found to merge with one another, and they become patchy fibrillar structures at 90°C. An optical direct band gap of 3.3 eV is measured for all the samples deposited above 50°C, while their transmittance varies from 40 to 75%, depending on their morphologies. X-ray photoelectron spectroscopy (XPS) shows that the ZnO nanostructures are covered by a Zn(OH) 2 overlayer, in good accord with the general growth model that involves Zn 2+ hydroxylation followed by dehydration to ZnO. Furthermore, our XPS data also reveals the presence of chlorine throughout the ZnO nanostructures, which verifies for the first time the 2D growth mechanism that involves Cl -capping of the (0001) plane of ZnO and thereby redirecting growth in the (101 h0) plane. Early growth of nanowalls at 70°C arising from spherical nanoparticles to elongated nanobars is demonstrated by varying the deposition time.

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Section: Introductionmentioning

confidence: 99%

Vertical Growth of Two-Dimensional Zinc Oxide Nanostructures on ITO-Coated Glass: Effects of Deposition Temperature and Deposition Time

2008

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“…A number of techniques have been used to fabricate nanorod arrays, including template synthesis, various forms of vapor deposition, chemical solution growth, electrochemical deposition, and sub-micrometer lithography. [2,7] Vapor deposition and lithographic methods are restricted by slow, expensive, high-vacuum processes, and chemical solution [5] and electrochemical [8,9] growth of free-standing arrays have largely been limited to certain materials, notably zinc oxide. A variety of oxide semiconductors have been proposed for use in nanostructured solar cells and many different metallic, semiconducting, and magnetic materials are of interest for data storage, sensing, catalysis and field emission devices, such that a more universal method is desirable.…”

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confidence: 99%

Low‐Temperature Synthesis of Large‐Area, Free‐Standing Nanorod Arrays on ITO/Glass and other Conducting Substrates

et al. 2008

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Arrays of free-standing nanorods or nanowires are of great interest for applications in data storage, catalysis, sensing, field emission, and optoelectronic devices. [1][2][3][4] Hybrid solar cells, for example, attempt to combine nanostructured semiconducting metal oxides with organic semiconductors to produce efficient photovoltaics at low cost. An ideal architecture proposed for these cells consists of an array of semiconducting nanorods surrounded by a charge-transporting polymer, where the interfacial distance is smaller than the exciton diffusion length in the polymer (approximately 10 nm), resulting in efficient exciton separation at the interface. [4][5][6] The development of such devices has so far been hindered by the inability to reliably produce nanostructures on appropriate substrates, including transparent conducting oxides and crystalline semiconductors. A general method is presented here for producing large-area arrays of free-standing nanorods on supporting substrates. The inclusion of titanium and tungsten adhesive layers has permitted the fabrication of anodic alumina thin film templates of unprecedented quality on indium tin oxide (ITO)/glass, silicon, and flexible substrates over 2 cm 2 areas, of interest for devices. For the first time, free-standing nanorods of a variety of oxides and metals have been reproducibly synthesized over large areas on ITO/glass substrates by electrochemical deposition into the vertically-aligned nanopores of the templates, followed by template removal. A number of techniques have been used to fabricate nanorod arrays, including template synthesis, various forms of vapor deposition, chemical solution growth, electrochemical deposition, and sub-micrometer lithography. [2,7] Vapor deposition and lithographic methods are restricted by slow, expensive, high-vacuum processes, and chemical solution [5] and electrochemical [8,9] growth of free-standing arrays have largely been limited to certain materials, notably zinc oxide. A variety of oxide semiconductors have been proposed for use in nanostructured solar cells and many different metallic, semiconducting, and magnetic materials are of interest for data storage, sensing, catalysis and field emission devices, such that a more universal method is desirable. The most versatile method for producing nanorods in the form of large-area arrays has been the replication of patterns in templates, using filling methods such as pressure injection, electrochemical deposition, and capillary filling with sol-gels. [7] Electrodeposition, in particular, is advantageous for electronic applications as it ensures that there is electrical contact between the deposited nanorods and underlying electrode. It is a low-temperature, inexpensive, scalable technique, which allows growth of a wide variety of metals and semiconductors. [2,[10][11][12] Both anodic aluminum oxide (AAO) and block copolymer [13] templates can be produced with self-assembling, vertically-aligned pores over a large area for nanorod synthesis. Anodic alumina templates in p...

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“…Various low-temperature processes for the fabrication of ZnO nanostructures have also been reported. They include a physical vapor-deposition technique using a NiO catalyst, [7] hydrothermal synthesis, [8] an aqueous route, [9] sol±gel electrophoretic deposition, [10] electrochemical growth, [11] ultrasonic spray-assisted chemical vapor deposition, [12] and pulsed-laser deposition. [13] Although interesting nanostructures can be produced via these techniques, future incorporation into nanoscale devices would suffer from a major drawback; the inability to position the nanostructures with nanoscale precision greatly impedes device design.…”

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confidence: 99%