Structural and physical properties of Ba_0.6Sr_0.4TiO₃ film prepared by pulsed laser deposition in a mixture of argon and oxygen

Abstract

In order to investigate the effect of argon introduction on the structural and physical properties of Ba 0.6 Sr 0.4 TiO 3 (BST) films, epitaxial BST films have been grown by pulsed laser deposition (PLD) on (001) oriented Nb-SrTiO 3 (STON) substrates in the ambient gas of pure oxygen and the mixture of argon and oxygen, respectively. The atomic force microscopy (AFM) reveals that the sample deposited in the mixture of argon and oxygen has a bigger grain size than that deposited in pure oxygen. The dielectric properties of two BST films have been investigated using the Pt/BST/STON parallel plate capacitors. The tunability and the figure of merit (FOM) of the BST film deposited in the mixture gas are about 41% and 7.07 at a DC bias voltage of 8 V at room temperature, which are better than 32% and 4.51, for BST film deposited in pure oxygen. On account of the introduction of argon, the leakage current density of the BST film deposited in the mixture gas has fallen by almost five times, and the leakage current mechanism is both in accordance with ohmic conductive mechanism.