Preparation of nickel oxide thin films for gas sensors applications

Nickel oxide (NiO) thin films were prepared by de reactive magnetron sputtering from a nickel metal target in an Ar + O-2 mixed atmosphere in two sputtering modes. The oxygen content in the gas mixture varied from 15% to 45%. The films prepared in the oxide-sputtering mode were amorphous while the films in metal-sputtering mode exhibited polycrystalline (fcc) NiO phase. In this case TEM observations showed a dense fine-grained structure with the grain size in the range 4-10 nm and AFM micrograph showed a rough surface with RMS = 2.21 nm. We have found that good NiO stoichiometric films are obtainable with a polycrystalline (fcc) structure at 40% oxygen content in the metal-sputtering mode. (C) 1999 Elsevier Science S.A. All lights reserved.