Influence of film thickness on the properties of sprayed ZnO thin films for gas sensor applications

Mariappan, R and Ponnuswamy, V and Suresh, P and Ashok, N and Jayamurugan, P and Bose, Chandra A (2014) Influence of film thickness on the properties of sprayed ZnO thin films for gas sensor applications. In: SUPERLATTICES AND MICROSTRUCTURES, 71 . pp. 238-249.

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Abstract

Transparent conducting ZnO films were prepared at substrate temperature 400 degrees C with different film thicknesses by nebulizer spray pyrolysis method on glass substrates. XRD studies reveal that the films are polycrystalline in nature having hexagonal crystal structure with preferred grain orientations along (0 0 2) and (1 0 1) directions. The crystallite size increases along (0 0 2) plane with the thickness increase and attains a maximum 109 nm for 913 nm film thickness. Analysis of structural parameters indicates that the films having thickness 913 nm are found to have minimum dislocation density and strain values. The HRSEM measurements show that the surface morphology of the films also changes with film thickness. EDAX estimates the average atomic percentage ratio of Zn and O in the ZnO films. Optical studies reveal the band gap energy decrease from 3.27 to 3.14 eV with increase of film thickness. Room temperature PL spectra show the near-band-edge emission and deep-level emission due to the presence of defects in the ZnO thin films. Impedance spectroscopy analysis indicates that grain boundary resistance decreases with the increasing ammonia concentration up to 500 ppm and the maximum sensitivity is found to be 1.7 for 500 ppm of ammonia. (C) 2014 Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Publication:	SUPERLATTICES AND MICROSTRUCTURES
Publisher:	ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Additional Information:	Copyright for this article belongs to the ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 24-28 OVAL RD, LONDON NW1 7DX, ENGLAND
Keywords:	Nebulizer spray pyrolysis; X-ray diffraction; Optical properties; Gas sensing properties
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	11 Aug 2014 04:45
Last Modified:	11 Aug 2014 04:45
URI:	http://eprints.iisc.ac.in/id/eprint/49540

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