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Structural and optical properties of Zn1−xCoxO and ZnCo2O4 thin films

Published online by Cambridge University Press:  01 February 2011

Kousik Samanta
Affiliation:
[email protected], University of Puerto Rico, Physics, PO.Box 23343, San Juan, Puerto Rico, 00931, Puerto Rico, 787-751-4210, 787-764-2571
Pijush Bhattacharya
Affiliation:
[email protected], University of Puerto Rico, Physics, Puerto Rico
Ram S. Katiyar
Affiliation:
[email protected], University of Puerto Rico, Physics, Puerto Rico
W. Iwamoto
Affiliation:
[email protected], Instituto de Fisica DEQ-UNICAMP Cidade Universitaria- Barao Geraldo 13083-970 Campinas, SP, Brazil., Fisica, Brazil
R. R. Urbano
Affiliation:
[email protected], Instituto de Fisica DEQ-UNICAMP Cidade Universitaria- Barao Geraldo 13083-970 Campinas, SP, Brazil., Fisica, Brazil
P. G. Pagliuso
Affiliation:
[email protected], Instituto de Fisica DEQ-UNICAMP Cidade Universitaria- Barao Geraldo 13083-970 Campinas, SP, Brazil., Fisica, Brazil
C. Rettori
Affiliation:
[email protected], Instituto de Fisica DEQ-UNICAMP Cidade Universitaria- Barao Geraldo 13083-970 Campinas, SP, Brazil., Fisica, Brazil
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Abstract

Thin films of Co substituted ZnO and ZnCo2O4 were deposited on c-axis (0001) oriented Al2O3 substrates using pulsed laser deposition. The XRD results showed all the films were highly (002) oriented with a less intense peak of (311) for ZnCo2O4 thin film. Micro-Raman spectra of ceramic targets showed the modes related to wurtzite ZnO and spinel ZnCo2O4 structures. In thin films of Zn1−xCoxO no modes corresponding to ZnCo2O4 were detected. The intensity of E1(LO) and multiphonon peak at 584 and 540 cm−1 respectively, increased with increase in Co substitution. The optical absorption of the films showed that the band gap decreased with increase of Co concentrations at room temperature along with the sub-bandgap absorptions due to d-d transitions of Co2+. Similar sub-bandgap d-d transition was also observed in the absorption spectra ZnCo2O4 thin films. The highest saturated magnetization (0.2μB/Co) was obtained for 5%Co substituted ZnO.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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References

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