A post-growth processing methodology to achieve barium strontium titanate thin films with low dielectric loss and high tunability for reconfigurable tunable devices

Ba_0.60Sr_0.40TiO₃ (BST) thin films, grown via RF-sputtering and the metalorganic solution deposition (MOSD) techniques, were post-growth annealed via conventional thermal annealing (CTA) and UV-photon irradiation annealing. With respect to the conventional thermal annealed films the UV-photon irradiation annealed films possessed improved structural properties and dielectric response. The optimization of the UV-photon irradiation annealing process parameters (using RF-sputtered BST films) was achieved via a detailed set of iso-thermal/chronal annealing experiments. The optimized UV-process parameters, applied to MOSD synthesized BST films revealed further enhanced dielectric response, i.e., 23% reduction in tan δ with sustained tunability of 42%. The improvements in the material properties of the UV-photon irradiation annealed BST thin films are attributed to stoichiometry and structural changes enabled through the UV-photon irradiation annealing process.