Influence of solvent on humidity sensing of sol-gel deposited ZnO thin films

¹ Laboratoire Microsystème et Instrumentation, Département d’électronique, Université de Constantine 1, route d’Ain El Bey, 25000 Constantine, Algeria
² Laboratoire Microstructure et Défauts dans les Matériaux, Département de physique, Université de Constantine 1, route d’Ain El Bey, 25000 Constantine, Algeria
³ Institut Jean Lamour, Département CP2S, UMR 7198 CNRS-Nancy-Université-UPV-Metz, École des Mines de Nancy, Parc de Saurupt, CS14234, 54042 Nancy, France
⁴ Département de physique, Université de Constantine 1, route d’Ain El Bey, 25000 Constantine, Algeria

^a e-mail: ch_boukaous@yahoo.fr

Received: 15 October 2013
Revised: 15 December 2013
Accepted: 17 December 2013
Published online: 3 February 2014

Abstract

Undoped zinc oxide (ZnO) thin films have been grown on glass substrates by sol-gel process associated with dip coating. Two different solvents are used such as: 2-methoxyethanol and ethanol. The influence of these solvents on structural and optical properties of ZnO thin films has been investigated. Crystallinity and surface morphology of ZnO films are analyzed using X-ray diffractometry (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The optical properties are characterized by ultraviolet-visible (UV-vis) and photoluminescence spectroscopy (PL). Humidity sensors have been prepared with deposited ZnO films. Results reveal that ZnO thin film synthesized with 2-methoxyethanol showed a better crystalline quality and ultraviolet emission performance. In addition, a smaller transmittance in visible range and a higher surface roughness are observed. Sensing humidity test exhibits better sensitivity for sensor prepared with film deposited using 2-methoxyethanol as solvent.