Dielectric and electrical properties of BaWO4 film capacitors deposited by RF magnetron sputtering

Abstract

We report the deposition, electric and dielectric characterization of BaWO4 (BWO) thin films using a RF magnetron sputtering technique. The effect of oxygen mixing percentage (OMP) on electrical and dielectric properties of the BaWO4 films has been studied systematically and reported for the first time. As deposited films are amorphous and annealing at 700°C induces the crystallinity. Surface morphology reveals a pronounced grain size reduction with OMP. Films deposited upto 50% OMP exhibited all the Raman vibrational modes and above that only few vibrational modes are presented. The dielectric properties of these films are studied as a function of both frequency (5kHz–1MHz) and temperature (320–450K). The measured dielectric properties show a progressive improvement with OMP and a maximum asset value of εr=15 and tanδ=0.019 at 1MHz are obtained for the film deposited at 50% OMP. This improvement is attributed to the crystallinity, uniform growth and reduction in oxygen vacancies. The activation energy of the mobile charge carriers obtained using the Arrhenius relation is found to be Ea=0.053, 0.013 and 0.002eV for the films with 0–50% OMP, respectively. The leakage current density is less than 10‾5A/cm2 at an applied electric field of 50kV/cm for all the films. The negative electric field region of leakage current shows ohmic conduction behavior up to 25kV/cm and above follows a space charge-limited current mechanism. However, in the positive field region, the BWO films exhibited only a space charge-limited current mechanism throughout the range.