Composition control of radio-frequency magnetron sputter-deposited La0.5Sr0.5CoO3-partial derivative thin films

For this paper, we used radio-frequency (rf) sputter deposition to synthesize epitaxial La0.5Sr0.5CoO3-partial derivative (LSCO) films. We investigated the influence of sputter deposition parameters, in particular, oxygen partial pressure, plasma power, total sputter pressure, and post-deposition cooling atmosphere on film composition, microstructure, and electrical resistivity. We show that rf sputtering from a single target can produce LSCO films with La/Sr and (La + Sr)/Co ratios of unity and with low electrical resistivities of about 1 mOmega cm. Film microstructures were characterized by high-resolution transmission electron microscopy and x-ray diffraction. Formation of an ordered film superlattice, most likely due to oxygen vacancy ordering, was observed. In this paper, we discuss the relationship between the film microstructure and the electrical resistivity.