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dc and ac transport properties of Mn-doped ZnO thin films grown by pulsed laser ablation

Dhananjay, * and Nagaraju, J and Krupanidhi, SB (2006) dc and ac transport properties of Mn-doped ZnO thin films grown by pulsed laser ablation. In: Materials Science and Engineering: B, 133 (1-3). pp. 70-76.

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Abstract

$Mn_xZn_{1-x}O$ (x = 0.20) thin films were deposited on Pt coated Si substrates using pulsed laser ablation technique. The structural characteristics of the films were investigated by X-ray diffraction (XRD), while the dielectric response of the films was studied as a function of frequency and ambient temperature by employing impedance spectroscopy. It was found that all the films deposited on Pt coated Si substrates had c-axis preferred orientation perpendicular to the substrate, with full width at half maximum (FWHM) of the (0 0 2) X-ray reflection line being less than $0.5^o$. The dc and ac electrical conductivity of Mn-doped ZnO films were investigated as a function of temperature. The ac conductivity, $\sigma_ac(\omega)$, varies as $\sigma_ac(\omega) = A\omega^s$ with s in the range 0.4–0.9. The complex impedance plot showed data points lying on a single semicircle, implying the response originated from a single capacitive element corresponding to the bulk grains. The value of the activation energy computed from the Arrhenius plot of both dc and ac conductivities with 1000/T were 0.2 eV suggesting hopping conduction mechanism. The optical properties of $Zn_{0.8}Mn_{0.2}O$ thin films were studied in the wavelength range 300–900 nm. The data were analyzed in the light of the existing theories and reflected a Burstein–Moss shift in these films. The films show magnetic properties, which are best described by a Curie–Weiss type behavior.

Item Type: Journal Article
Additional Information: Copyright of this article belongs to Elsevier.
Keywords: Impedance spectroscopy;Hopping conduction;Burstein–Moss shift
Department/Centre: Division of Physical & Mathematical Sciences > Instrumentation and Applied Physics (Formally ISU)
Division of Chemical Sciences > Materials Research Centre
Date Deposited: 21 Nov 2006
Last Modified: 19 Sep 2010 04:32
URI: http://eprints.iisc.ernet.in/id/eprint/8891

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