Dielectric and structural properties of pulsed laser deposited and sputtered barium strontium titanate thin films

Ba0.5Sr0.5TiO3 thin films have been deposited on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition and sputtering. The deposition conditions to achieve high tunability and low dielectric loss were optimized for both the techniques. The structural characterization of the barium strontium titanate (BST) thin films was performed by X-ray diffraction (XRD) and atomic force microscopy (AFM). The diffraction patterns from XRD analysis are attributed to cubic (perovskite) crystal system. Parallel plate capacitors were fabricated and measured in the frequency range of 1–300 MHz. The deposition conditions to achieve high tunability and low dielectric loss were optimized. A tunability of 2.4:1 and a loss tangent of 0.025 were achieved at 20 MHz for pulsed laser deposited BST thin films. A tunability of 2.8:1 and a loss tangent of 0.01 were achieved in frequency range from 10 to 200 MHz for sputtered BST thin films.