Epitaxial and highly electrical conductive La0.5Sr0.5TiO3 films grown by pulsed laser deposition in vacuum

Abstract

The target material with nominal composition of La0.5Sr0.5TiO3 sintered in air is an insulator and not a single-phase compound. By pulsed laser ablation in vacuum at the multiphase La–Sr–Ti–O target, however, highly electrical conductive and epitaxial La0.5Sr0.5TiO3 films have been fabricated on LaAlO3(001) substrates. Structural characterization using three-axis x-ray diffraction (θ–2θ scan, ω-scan rocking curve, and φ scan) reveals that the films have a pseudocubic structure and grow on the substrates with a parallel epitaxial relationship. Atomic force microscopy images show the films have quite smooth surface, for a film 200 nm thick, the roughness Ra is about 0.31 nm over the 1 μm×1 μm area. Resistivity versus temperature measurements indicate that the films are metallic at 2–300 K and have resistivity of 64 μΩ cm at 300 K, which is about one order lower than that of the single-phase La0.5Sr0.5TiO3 bulk materials. After the same deposition procedure, epitaxial La0.5Sr0.5TiO3 films have also been grown on TiN buffered (001) Si substrates.