In situ surface characterization of SrTiO 100/substrates and 3 homoepitaxial SrTiO thin films grown by molecular beam 3 epitaxy and pulsed laser deposition

The topmost atomic layer of SrTiO3 STO.substrates was investigated by in situ low-energy ion scattering spectroscopy LEISS.. After mechanochemical polishing, the topmost layer of the STO substrate consisted of SrO and TiO2 planes. It was dominantly stabilized with TiO2 planes after the STO substrate was treated with a pH-controlled NH4F–HF BHF.solution. STO thin films were deposited on the BHF-treated STO substrates by the molecular beam epitaxy MBE.and pulsed laser deposition PLD.methods. STO films were confirmed to have topmost layers with TiO2 planes by the MBE method, and SrO planes by the PLD method. We also investigated the effects of the deposition conditions and surface treatments, and confirmed that the TiO2 plane was more stable on the STO homoepitaxial film surface. Furthermore, the BHF-treated STO substrates greatly improved the thickness dependence of Tc of heteroepitaxial YBa2Cu3Ox YBCO.ultra-thin films. q1998 Elsevier Science B.V. All rights reserved.