The Effects of Mg Doping on the Materials and Dielectric Properties of Ba1-xSrxTiO3 Thin Films

Abstract

AbstractWe have investigated the dielectric, insulating, structural, microstructural, interfacial, and surface morphological properties of Ba0.60Sr0.40TiO3 thin films Mg doped from 0 to 20 mol%. A strong correlation was observed between the films structural, dielectric and insulating properties as a function of Mg doping. Non textured polycrystalline films with a dense microstructure and abrupt film--Pt electrode interface were obtained after annealing at 750°C for 30 min. Single phase solid solution films were achieved at Mg doping levels up to 5 mol%, while multiphased films were obtained for Mg doping levels of 20 mol%. Decreases in the films dielectric constant, dielectric loss, tunability and leakage current characteristics were paralleled by a reduction in grain size as a function of increasing Mg dopant concentration. Our results suggest that Mg doping serves to limit grain growth and is thereby responsible for lowering the dielectric constant from 450 to 205. It is suggested that Mg behaves as an acceptor-type and is responsible for the doped films low dielectric loss and good leakage current characteristics. Performance-property trade-offs advocates the 5 mol% Mg doped Ba0.60Sr0.40TiO3 film to be an excellent choice for tunable microwave device applications.