Growth of homoepitaxial $SrTiO3$ thin films by molecular-beam epitaxy

We report the structural properties of homoepitaxial (100) $SrTiO3$ films grown by reactive molecular-beam epitaxy (MBE). The lattice spacing and x-ray diffraction (XRD) rocking curves of stoichiometric MBE-grown $SrTiO3$ films are indistinguishable from the underlying $SrTiO3$ substrates. Off-stoichiometry for both strontium-rich and strontium-poor compositions (i.e., $Sr1+xTiO3+δ$ films with $−0.2<x<0.2$⁠) results in lattice expansion with significant changes to the shuttered reflection high-energy electron diffraction oscillations, XRD, and film microstructure. The dependence of lattice spacing on nonstoichiometry is smaller for MBE-grown films than for homoepitaxial (100) $Sr1+xTiO3+δ$ films prepared by pulsed-laser deposition or sputtering.