Electrical properties of nickel oxide thin films for flow sensor application

In this work, Ni oxide thin films, with thermal sensitivity superior to Pt and Ni thin films, were formed through annealing of Ni films deposited by a r.f. magnetron sputtering. The annealing was carried out in the temperature range of 300-500 degrees C under atmospheric conditions. Resistivity of the resulting Ni oxide films were in the range of 10.5 mu Omega cm/degrees C to 2.84 x 10(4) mu Omega cm/degrees C, depending on the extent of Ni oxidation. The temperature coefficient of resistance (TCR) of the Ni oxide films also depended on the extent of Ni oxidation; the average TCR of Ni oxide resistors, measured between 0 and 150 degrees C, were 5630 ppm/degrees C for the 300 degrees C and 2188 ppm/degrees C for 500 degrees C films. Because of their high resistivity and very linear TCR, Ni oxide thin films are superior to pure Ni and Pt thin films for flow and temperature sensor applications. (c) 2005 Elsevier B.V. All rights reserved.