Fabrication of nanostructured palladium-doped SiO2 films with variable temperature coefficient of resistivity

Electrical characteristics of palladium (Pd)-doped glass films of various Pd concentrations, which contain nanometer-sized Pd ultrafine particles, were studied. Temperature dependence showed that the temperature coefficient of resistivity (alpha) increased with decreasing resistivity; also, the sign of alpha changed from negative to positive. The critical resistivity at which alpha = 0 was within the range of 10(0)-10(-2) Omega cut, where temperature-independent resistance films can be designed. In films within this resistivity range, the sign of a changed to positive after annealing at 500 degreesC, demonstrating a metal-insulator transition characteristic before and after heat treatment. In a metallic regime having lower resistivity, the value of alpha and resistivity remained sufficiently small and higher than ordinary bulk metal, which phenomenon was discussed with a conduction model. (C) 2004 Elsevier B.V. All rights reserved.