Fabrication of conductive SrRuO3 thin film and Ba0.60Sr0.40TiO3/SrRuO3 bilayer films on MgO substrate

Conductive SrRuO3 (SRO) thin films have been grown on (100) MgO substrates by pulsed laser deposition (PLD) technique. Effects of oxygen pressure and deposition temperature on the orientation of SRO thin film were investigated. X-ray diffraction (XRD) theta/2 theta patterns and the temperature dependent resistivity measurements indicated that oxygen pressure of 30 Pa and deposition temperature of 700 degrees C were the optimized deposition parameters. A parallel-plate capacitor structure was prepared with the SRO films deposited under optimized condition as an electrode layer and Ba0.60Sr0.40TiO3 (BST) thin film as the dielectric layer. XRD Phi scans indicated a [001]BST//[100/001]SRO//[001]MgO epitaxial relationship between BST and SRO on MgO substrate. The dielectric constant and loss tangent measured at 10 kHz and 300 K was 427 and 0.099 under 0 V bias, and 215 and 0.062 under 8 V bias, respectively. A tunability of 49.6% has been achieved with DC bias as low as 8 V. The C-V hysteresis curve and the P-E hysteresis loop suggested that the BST films epitaxially grown on SRO/MgO have ferroelectricity at room temperature. The induced ferroelectricity was believed to originate from the compressive strain between the epitaxial BST and SRO thin films. These results show the potential application of the BST/SRO heterostructures in microelectronic devices.