P-type NiO thin films prepared by sputtering for detection of pollutants

Year: 2014

Authors: Kumar R., Baratto C., Faglia G., Sberveglieri G., Bontempi E., Borgese L.

Autors Affiliation: Department of Information Engineering, CNR-IDASC, University of Brescia, Via Valotti 9, 25133 Brescia, Italy; INSTM and Chemistry for Technologies Laboratory, Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25133 Brescia, Italy

Abstract: NiO thin films were deposited by RF reactive magnetron sputtering and investigated in view of application as p-type material for sensing of pollutants. The thin films were deposited on Si-wafer, glass and alumina substrate using a nickel oxide target at variable gas mixture of O 2/Ar. Ratio of O2/Ar was varied from 0, 10, 25 to 50 %, and the deposition temperatures were varied from RT to 400 C. The phase formation and structural analysis of the samples were analysed by GIXRD (glancing incidence X-ray diffraction). GIXRD confirmed the NiO phase formation in thin film deposited at 50 % O2 content. Surface morphology was analysed by scanning electron microscope (SEM). The thin films deposited are flat and uniform: in some cases, we found tetrahedral-shaped particles with dimension ~30 nm. We observed that the oxygen content in the gas mixture of O2/Ar and post-deposition annealing temperature were the crucial factors which have deep impact to tailor the structural properties and the surface morphology of thin NiO films. The gas sensing properties of the designed systems were investigated in the presence of ethanol, NO2 and CO, respectively, with variable temperature from 200 to 400 C. A good response was obtained towards NO2 at 300 C operating temperature and to ethanol with optimum working temperature at 400 C. A low response was observed towards CO.

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KeyWords: Alumina; Deposition; Ethanol; Gas mixtures; Microsystems; Mixtures; Nickel oxide; Nitrogen oxides; Pollution detection; Scanning electron microscopy; Sensors; Surface morphology; X ray diffraction, Deposition temperatures; Detection of pollutant; Gas sensing properties; Glancing incidence x-ray diffractions; Operating temperature; Post deposition annealing; RF reactive magnetron sputtering; Working temperatures, Thin films
DOI: 10.1007/978-3-319-00684-0_23