Realization of controllable etching for ZnO film by NH4Cl aqueous solution and its influence on optical and electrical properties

Sun, Jingchang; Bian, Jiming; Liang, Hongwei; Zhao, Jian; Hu, Lizhong; Zhao, Zhizhong; Liu, Weifeng; Du, Guotong

doi:10.1016/j.apsusc.2006.11.036

Cited by 66 publications

(39 citation statements)

References 28 publications

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“…Solutions of reagents can be transported to the flow cell 34 either by computer controlled peristaltic reagent pumps 35 or by gravity. Ammonium chloride has been shown to be an effective and controllable etchant for ZnO, 36 and in the QCM-flow reactor experiments a 5 mM solution in 95% ethanol was used as a probe of SAM quality. The crystal resonance frequency was monitored with a commercial crystal monitor 37 and converted to thickness within LabVIEW using the following relation developed by Lu and Lewis: 77 where ∆m is the thickness in g/cm 2 , N q is a frequency constant for the crystal, F q is the density of quartz, R z is the Z-factor or ratio of the acoustic impedances of quartz and the film material, f q is the frequency of the unloaded crystal, and f is the frequency of the loaded crystal.…”

Section: Experimental Methodsmentioning

confidence: 99%

Molecular Anchors for Self-Assembled Monolayers on ZnO: A Direct Comparison of the Thiol and Phosphonic Acid Moieties

Perkins

2009

J. Phys. Chem. C

108

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Two of the most promising schemes for attaching organic molecules to metal oxides are based on the chemistry of the thiol and phosphonic acid moieties. We have made a direct comparison of the efficacy of these two molecular anchors on zinc oxide by comparing the chemical and physical properties of n-hexane derivatives of both. The surface properties of polycrystalline ZnO thin films and ZnO(0001 j )-O crystals modified with 1-hexanethiol and 1-hexanephosphonic acid were examined with a novel quartz crystal microbalance (QCM)-based flow cell reactor, angle-resolved and temperature-dependent photoelectron spectroscopy, and contact angle measurements. A means of using ammonium chloride as a probe of molecule-ZnO interactions is introduced and used to ascertain the relative quality of self-assembled monolayers (SAMs) based on thiols and phosphonic acids. QCM data shows that a phosphonic acid-anchored alkyl chain only six carbons long can provide significant corrosion protection for ZnO against Brønsted acids, reducing the etch rate relative to the bare ZnO surface by a factor of more than nine. In contrast, we find that monolayers from the analogous molecule hexanethiol are more defective as revealed by their higher ionic permeability and lower hydrophobicity. Substrate attenuation X-ray photoelectron spectroscopy (XPS) experiments were used to determine the thickness of SAMs formed by the two hexane derivatives and it was found that SAMs from phosphonic acids were approximately twice as thick as those formed by hexanethiol. The thermal stability of the two linking groups was also explored and we find that previous claims of highly stable alkanethiolate monolayers on ZnO are suspect. Taken as a whole, our results indicate that the phosphonic acid moiety is preferred over thiols for the attachment of short alkyl groups to ZnO.

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Section: Experimental Methodsmentioning

confidence: 99%

Molecular Anchors for Self-Assembled Monolayers on ZnO: A Direct Comparison of the Thiol and Phosphonic Acid Moieties

Perkins

2009

J. Phys. Chem. C

108

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“…Furthermore, the full width at half maximum (FWHM) of ZnO nanorods is narrower than that of ZnO buffer layer. It is believed that higher surface area to volume ratio may seriously influence the PL process [17,18] . The number of photongenerated carrier in surface states in a grain is proportional to the number of atoms on the surface.…”

Section: Resultsmentioning

confidence: 99%

Self-catalyst synthesis of aligned ZnO nanorods by pulsed laser deposition

et al. 2009

Sci. China Ser. G-Phys. Mech. Astron.

Self Cite

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High-density well-aligned ZnO nanorods were successfully synthesized on ZnO-buffer-layer coated indium phosphide (InP) (100) substrates by a pulsed laser deposition (PLD) method. Scanning electron microscopy images show that the ZnO buffer layer formed uniform drip-like structure and ZnO nanorods were well-oriented perpendicular to the substrate surface. The sharp diffraction peak observed at 34.46° in X-ray diffraction scanning pattern suggests that the ZnO nanorods exhibit a (002)-preferred orientation. The PL spectra of ZnO samples shows a strong near band edge emission centered at about 380 nm and a weak deep level emission centered at around 495 nm, and it demonstrates that the ZnO nanorods produced in this work have high optical quality, which sheds light on further applications for nanodevices.ZnO, nanorods, buffer-layer, self-catalyst, pulsed laser deposition In recent years, semiconductor nanostructures have attracted much attention due to their potential applications in a wide range of advanced devices. Among these nanostructures, ZnO nanostructures arrays have been considered to be the most prospective one due to its direct wide band gap of 3.37 eV and a large exciton binding energy of 60 meV [1] , which has been recognized as a promising candidate for applications in functional oxide-based. Additionally, it may be used for electromechanical coupled sensors, transducers and biomedical applications [2][3][4] , because of its piezoelectric and biocompatible properties, respectively. Furthermore, various techniques are employed to fabricate ZnO nanostructures, such as chemical vapor deposition (CVD) [5] , metal-organic chemical vapor deposition (MOCVD) [6] , thermal evaporation [7] , molecule beam epitaxy (MBE) [8] , and pulsed laser deposition (PLD) [9] . Therefore, ZnO nanostructures have attracted so much attention, and a large number of publications have been presented recently for reporting ZnO nanostructures with diverse morphologies grown by different approaches. Wang et al. [10] and Gao et al. [11] demonstrated the synthesis of ZnO nanostructures by a solid-vapor phase thermal sublimation technique. This approach is the most widely used technique for synthesizing aligned ZnO nanostructures, in which the assistance of metal catalysts are frequently chosen, such as Au, Co, and Cu, commonly introducing impurities in the products. Consequently, it is necessary to develop catalyst-free growth techniques of ZnO nanostructures. Vayssieres [12] grew arrayed ZnO nanorods and nanowires by a catalyst-free aqueous solutions method. Chen et al. [13] also synthesized flower-like ZnO nanorods by a catalyst-free sonochemical method. However, there is no report about self-catalyst preparing ZnO nanostructures by a PLD technique.As we known, only sparse ZnO nanostructures were prepared on InP substrates by a PLD method. The main

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“…The Ostwald-ripening effect may result in partial dissolution of some crystallographic planes or some sites of the same crystallographic planes, so as to give ZnO with different morphologies and crystalline characteristics. 87,105,118,119 This process somewhat resembles that of a top-down reconstruction. In Zn(NO 3 ) 2 -HMT solution, a rod-shaped ZnO formed at the early stage of the reaction has been observed to become nanoscrews, 105 nanotubes, 87 and even nanoplates 119 after a long time aging.…”

Section: Morphological Evolution In Solutionmentioning

confidence: 99%

Nano/Micro Patterning of Inorganic Thin Films

Koumoto¹,

Saito²,

Gao³

et al. 2008

Bulletin of the Chemical Society of Japan

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The present review is focused on the site-selective deposition of inorganic thin films on self-assembled monolayer (SAM) templates. SAMs were used to modify the substrate surface with chemical functional groups. The patterned SAM substrate was prepared by exposing the SAM substrate to UV light through photomasks for photocleavage. The patterned SAM was used as the templates for deposition of ceramic thin films in aqueous solutions. The preparation and characterization methods of SAMs, and the preparation of the patterned SAM templates are explained. Solution chemistry for the deposition of ceramic oxides and the physics and chemistry of interfaces are described. Experimental examples are given to explain how these aspects influence the formation of films and their properties. Various examples of site-selective deposition of ceramic oxides on SAM templates are explained with classification into three categories: patterning by site-selective attachment of homogeneously nucleated particles, patterning by surface-selective heterogeneous nucleation and growth, and patterning by catalyst-induced heterogeneous nucleation. We also describe pattern-deposition on flexible substrates and future views to improve the pattern resolution.

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Realization of controllable etching for ZnO film by NH4Cl aqueous solution and its influence on optical and electrical properties

Cited by 66 publications

References 28 publications

Molecular Anchors for Self-Assembled Monolayers on ZnO: A Direct Comparison of the Thiol and Phosphonic Acid Moieties

Molecular Anchors for Self-Assembled Monolayers on ZnO: A Direct Comparison of the Thiol and Phosphonic Acid Moieties

Self-catalyst synthesis of aligned ZnO nanorods by pulsed laser deposition

Nano/Micro Patterning of Inorganic Thin Films

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