The electronic conduction mechanism in magnesium-doped Ba0.4Sr0.6TiO3 thin films for varactor application

Sol-gel derived magnesium-doped ferroelectric Ba0.4Sr0.6TiO3 (with Mg dopant to be 5 mol%, 10 mol%, and 15 mol% ) (BSMT) thin films are deposited on Pt(111)/Ti/SiO2/Si(100) substrate and annealed at 650 ∘C, 700 ∘C, and 750 ∘C, respectively. In the low field (<115 kV/cm), the electrical conduction leakage behavior was investigated by considering the Schottky current model and the Schottky-limited current model in this paper. The extracted values of optical dielectric constant ε reveal the experiment results agree well with the Schottky-limited current model for low voltage. At higher voltage, the space-charge-limited conduction (SCLC) mechanism was also shown. In conclusion, Schottky-limited current mechanism and SCLC are given for the electrical conduction leakage behavior in the Mg-doped BST thin film.