The influences of preparation parameters on NiO thin film properties for gas-sensing application

Nickel oxide (NiO) thin films have been prepared by dc reactive magnetron s puttering from a metallic Ni target in an Ar + O-2 mixed atmosphere in two sputtering modes. The oxygen content in the gas mixture varied from 15 to 4 5%. Rutherford backscattering spectrometry (RBS) and X-ray photoelectron sp ectroscope (XPS) investigations have been used for the study of the chemica l composition and to detect different chemical states of bond elements. TEM observations revealed a dense fine-grained structure with the grain size i n the range 4-10 nm. Atomic force microscopy (AFM) showed that the surface morphology NiO films can be modified by the process parameters as the oxyge n content and the pumping speed. Scanning electron microscope (SEM) observa tion and energy dispersive X-ray (EDX) analyses revealed uniform morphology and homogenous dispersion of NiO, Pt and Al2O3 phases. In addition, the Ni O thin films were tested in order to investigate their response to CO in th e range 50-200 ppm at different operating temperatures. (C) 2001 Elsevier S cience B.V. All rights reserved.