Fabrication and characterization of iron and fluorine co-doped BST thin films for microwave applications

Abstract

The effects of fluorine co-doping by means of a post-thermal annealing process of iron-doped BST thin films in a fluorine-containing atmosphere have been investigated. XPS and ToF-SIMS sputter depth profiling verified a homogeneous fluorine distribution in the thin films. By employing EPR, it was shown that singly charged ( $$ {\text{Fe}}_{\text{Ti}}^{\prime } $$ – $$ {\text{V}}_{\text{O}}^{ \cdot \cdot } $$ )· defect complexes, as well as ‘isolated’ $$ {\text{Fe}}_{\text{Ti}}^{\prime } $$ centres with a distribution of $$ {\text{F}}_{\text{O}}^{ \cdot } $$ sites in remote coordination spheres exist in the fluorinated films. Tunability enhancement due to fluorine co-doping as well as a Q-factor enhancement due to iron doping is demonstrated.