Nature and Behaviour of WO3 Thick Film Resistors Properties When Subjected to Firing Temperature

Abstract

WO3-based thick film resistors were prepared by using standard screen printing technique. This paper was aimed at studying the nature and behaviour due to effect of firing temperature on resistors fired in the range 500-700 0 C in air atmosphere. The material characterization was performed by XRD, SEM, and EDAX for elemental analysis. A mixture of monoclinic, triclinic and hexagonal WO3 was observed in the range 500-700 0 C. The UV-visible spectra show WO3 exhibits a shoulder at 230 nm along with an ill-defined band at 260 nm. The maximum optical band gap energy of 4.85 eV was calculated at room temperature. The D.C. resistance of the films was measured by half bridge method in air atmosphere at different temperatures. The films showed decrease in resistance with increase in temperature indicating semiconductor behaviour. The TCR, activation energy and sheet resistivity of films were evaluated at different firing temperatures.