Cu-doping effects on the dielectric and insulating properties of sol-gel derived Ba0.7Sr0.3TiO3 thin films

Undoped and Cu-doped Ba0.7Sr0.3TiO3 (BST) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by a sol-gel spin coating process. The dielectric and insulating properties of BST thin films with different Cu content were investigated. The amount of Cu dopant had a strong influence on the dielectric and insulating properties of BST thin films. A BST thin film with optimized Cu content of 1.5 mol% exhibits dielectric loss of 0.045 and tunability of 49.2 %, which are superior to the dielectric loss of 0.053 and tunability of 35.6 % for undoped BST thin film. Furthermore, the leakage current density of 1.62 x 10(-5) A/cm(2) for 1.5-mol% Cu-doped BST thin film at 150 kV/cm was about I order of magnitude lower than 1.34 x 10(-4) A/cm(2) for undoped BST thin film.