Low-temperature crystallization of BST thin films on RT/Duroid substrate for tunable microwave devices

Barium strontium titanate (BST-Ba0.5Sr0.5TiO3) thin films are deposited over RT/Duroid substrate at a temperature of 250°C and are then crystallized by laser annealing. The laser annealed films are XRD crystalline. The microwave dielectric properties are measured by fabricating circular patch capacitor (CPC) using these dielectric films and a maximum tunability of 34% is obtained. Thus, integrated monolithic varactors on a polymer composite substrate exploiting the electric fielddependent dielectric constant exhibited by crystalline ferroelectric thin films are demonstrated.