IMF2017

The Pulsed Laser Deposition (PLD) technique offers several key advantages with respect to Molecular Beam Epitaxy (MBE) for the growth of epitaxial SrTiO₃ (STO) ultra-thin films on Si, but the research on PLD growth of these materials is scarce. A novel procedure, which uses a ½ ML buffer layer of Sr grown also by PLD, has been developed over the last two years at our group. It uses separate STO deposition, oxidation and crystallization stages for the growth of 10-12 ML samples, in order to minimize the interface reactions. In this work, the impact of the coverage deposited after the STO oxidation and crystallization stages, along with the crystallization method, is tested and optimized with in-situ and real-time RHEED, and ex-situ XPS, AFM and XRR measurements. It has been found that a combination of oxidation and crystallization every 2 ML improves the surface crystallinity and minimizes the crystallization starting temperature. The minimization of the thermal budget improves the interface quality, but decreases the STO density, while the composition and morphology of the samples stay close to that from stoichiometric STO. These results can be explained as a result of the balance between the critical thickness, minimum energy and proper Sr/Si coverage, and they improve the general knowledge about this growth and interface, allowing for the growth of high-quality templates for the epitaxial overgrowth of other complex oxides in a more efficient way.