Crystal orientation dependent microwave dielectric properties of sputtered SBTi thin films on fused silica substrates

摘要

Thin films of SBTi (SrBi_4iO_(15)) were deposited on fused silica substrates by rf-magnetron sputtering at substrate temperatures from 600 to 725 ℃. The effect of substrate temperature on preferential orientation, micro-structure, Raman scattering characteristics and microwave dielectric properties of SBTi thin films were investigated. Microwave dielectric properties were investigated using the Split Post Dielectric Resonator (SPDR) technique. As the substrate temperature increases, the preferential orientation changes from (119) to (0010). Films deposited at 700 ℃ exhibits less lattice distortion. It exhibits a dielectric constant about 110 and loss tangent about 0.06 at 10 GHz. It is seen from the Raman analysis that the films deposited at higher temperatures orients more towards c-axis which releases the torsional vibration mode involving TiO6 octahedra with a higher oscillator strength resulting in larger values of dielectric constant and dielectric loss for those films.