FABRICATION AND ANOMALOUS CONDUCTING BEHAVIOR OF ATOMICALLY REGULATED (SRVO3-X)/(SRTIO3-Y) SUPERLATTICES

Fine streak patterns and intensity oscillations were observed in RHEED diagnoses of the growth of perovskite-type SrVO3-x and SrTiO3-y films by pulsed laser deposition in ultrahigh vacuum. The oscillation periodicity coincided with the a-axis length of the perovskite oxide, indicating that the films were grown not only epitaxially but also laterally, i.e. in a layer-by-layer mode. This enabled us to fabricate SrVO3-x/SrTiO3-y superlattices with digital control of each layer thickness by counting the peak numbers of RHEED intensity oscillation. All of the as-grown SrVO3-x, SrTiO3-y, and superlattice films were highly conductive, but the temperature-dependent resistivity of the superlattice exhibited a behavior quite different from those of SrVO3-x and SrTiO3-y films. A metal-semiconductor transition observed in the superlattice at about 100K suggests a phenomenon originating from the two dimensionality of conducting layers.