Electrical behavior of Y-doped Ba0.6Sr0.4TiO3 thin films

Ba0.6Sr0.4TiO3 (BST) and 1.5 at% Y-doped Ba0.6Sr0.4TiO3 (Y-BST) thin films have been deposited on single-crystal (100) oriented LaAlO3 substrates using pulsed-laser deposition technique (PLD), respectively. X-ray diffraction (XRD) scanning revealed that the two kinds of films could be epitaxially grown in pure single-oriented perovskite phases, but Y-BST thin films showed an enhanced crystallization effect. The dielectric properties of the pure and Y-BST thin films were measured at 10 kHz and 300 K with a parallel-plate capacitor configuration. The results revealed that the addition of Y as an acceptor doping is very effective to increase dielectric tunability, and to reduce leakage current of BST thin films. The figure-of-merit (FOM) factor value increases from 17.32 for BST to 25.84 for Y-BST under an applied electric field of 300 kV/cm. The leakage current density of the BST thin films at a negative bias field of 300 kV/cm decreases from 2.45 × 10−4 A/cm2 to 1.55 × 10−6 A/cm2 by Y doping. The obtained results indicated that the Y-doped BST thin film is a promising candidate material for tunable microwave devices.