Solution-based synthesis of cobalt-doped ZnO thin films

Abstract

Publisher rights This is the author's version of a work that was accepted for publication in Thin Solid Films. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Thin Solid Films, Vol. 524, 01/12/2012 General rights Copyright for the publications made accessible via the Queen's University Belfast Research Portal is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights.Take down policy The Research Portal is Queen's institutional repository that provides access to Queen's research output. Every effort has been made to ensure that content in the Research Portal does not infringe any person's rights, or applicable UK laws. If you discover content in the Research Portal that you believe breaches copyright or violates any law, please contact openaccess@qub.ac.uk. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT1 Solution-based synthesis of cobalt-doped ZnO thin films Sesha VempatiSchool of Mathematics and Physics, Queen's University Belfast, BT7 1NN, UK, Amitha ShettyMaterials Research Center, Indian Institute of Science, Bangalore -560012, India. P. Dawson*School of Mathematics and Physics, Queen's University Belfast, BT7 1NN, UK, K. K. Nanda and S.B. KrupanidhiMaterials Research Center, Indian Institute of Science, Bangalore -560012, India.Corresponding author: p.dawson@qub.ac.uk AbstractUndoped and cobalt-doped (1-4 wt%) ZnO polycrystalline, thin films have been fabricated on quartz substrates using sequential spin-casting and annealing of simple salt solutions. X-ray diffraction (XRD) reveals a wurzite ZnO crystalline structure with high-resolution transmission electron microscopy showing lattice planes of separation 0.26 nm, characteristic of (002) planes.The Co appears to be tetrahedrally co-ordinated in the lattice on the Zn sites (XRD) and has a charge of +2 in a high-spin electronic state (X-ray photoelectron spectroscopy). Co-doping does not alter the wurzite structure and there is no evidence of the precipitation of cobalt oxide phases within the limits of detection of Raman and XRD analysis. Lattice defects and chemisorbed oxygen are probed using photoluminescence and Raman spectroscopy -crucially, however, this transparent semiconduc...

Selective isolation of the electron or hole in photocatalysis: ZnO–TiO2 and TiO2–ZnO core–shell structured heterojunction nanofibers via electrospinning and atomic layer deposition

“…The XRD pattern indicated a polycrystalline ZnO which was found to be consistent with the literature. 40,41,43,47 The lattice parameters were derived and the c/a ratio of $1.6 further supports the wurtzite structure and successful formation of ZnO. Since we have collected the nanobers on Al foil and calcined them aer the ALD process, a background of aluminum oxide is evidenced in the TiO 2 -ZnO CSHJ (designated with '*' on Fig.…”

“…3c and d for TiO 2 and ZnO, respectively. [40][41][42] We have also recorded EDX on CSHJs from TEM and the results are given in S2 of the ESI. † For both the cases a signal from Zn and Ti is seen as expected, however, the signal from the shell region dominates.…”

“…The surface characterization of the semiconductors such as ZnO 40,41,47 and TiO 2 (ref. 48 and 49) is of prime importance not only in the context of PL but also in conjunction with the PCA.…”

Role of zinc interstitials and oxygen vacancies of ZnO in photocatalysis: a bottom-up approach to control defect density

“…However, in the present case, the fwhm does not vary signicantly across all samples, while the area under the peak (A) appeared to improve from PZ1 QD to the rest of the samples, indicating slightly improved optical quality. 16,31,32 The next region to consider is violet emission, b [1][2][3][4] , where the fwhm is almost the same for all samples. Further, PZ1 QD has shown the lowest A, which nominally increased with ALD cycle numbers.…”

“…Note that studies based on Zn i s are less frequent than V O s because the former defects are difficult to achieve and control in the as-prepared samples. 16,17,[28][29][30][31][32] In contrast, typically synthesized ZnO is predominant with V O s. 4,8,16,17,27,31,32 Consequently, photocatalysis studies involving V O s dominate the literature. 1,4,6,[8][9][10]13,21 In this context, it is very useful and important to study the effect of Zn i s in PCA and their efficiency against V O s. In addition to the fundamental interest, the results of such a study enable an efficient and cost effective design of novel photocatalysts.…”