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.