Chemistry and structure of homoepitaxial SrTiO3 films and their influence on oxide-heterostructure interfaces
| Autor: | M. L. Reinle-Schmitt, C. Cancellieri, A. Cavallaro, G. F. Harrington, S. J. Leake, E. Pomjakushina, J. A. Kilner, P. R. Willmott |
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| Rok vydání: | 2014 |
| Předmět: |
Technology
Materials science SURFACE Chemistry Multidisciplinary Materials Science FOS: Physical sciences Materials Science Multidisciplinary Substrate (electronics) Conductivity Physics Applied Pulsed laser deposition 2-DIMENSIONAL ELECTRON-GAS Lattice constant 10 Technology SEGREGATION General Materials Science Nanoscience & Nanotechnology DEPOSITION Thin film Condensed Matter - Materials Science Science & Technology 02 Physical Sciences Zener effect Condensed matter physics Physics Materials Science (cond-mat.mtrl-sci) Order (ring theory) Heterojunction cond-mat.mtrl-sci Chemistry Physical Sciences Science & Technology - Other Topics 03 Chemical Sciences |
| Zdroj: | Nanoscale. 6(5) |
| ISSN: | 2040-3372 |
| Popis: | The properties of single-crystal SrTiO$_{3}$ substrates and homoepitaxial SrTiO$_{3}$ films grown by pulsed laser deposition have been compared, in order to understand the loss of interfacial conductivity when more than a critical thickness of nominally homoepitaxial SrTiO$_{3}$ is inserted between a LaAlO$_{3}$ film and a SrTiO$_{3}$ substrate. In particular, the chemical composition and the structure of homoepitaxial SrTiO$_{3}$ investigated by low-energy ion-scattering and surface x-ray diffraction, show that for insulating heterointerfaces, a Sr-excess is present between the LaAlO$_{3}$ and homoepitaxial SrTiO$_{3}$. Furthermore, an increase in the out-of-plane lattice constant is observed in LaAlO$_{3}$, indicating that the conductivity both with and without insertion of SrTiO$_{3}$ thin film originates from a Zener breakdown associated with the polar catastrophe. When more than a critical thickness of homoepitaxial SrTiO$_{3}$ is inserted between LaAlO$_3$ and SrTiO$_3$, the electrons transferred by the electronic reconstruction are trapped by the formation of a Sr-rich secondary phase and Sr-vacancies. The migration of Sr towards the surface of homoepitaxial STO and accompanying loss of interfacial conductivity can be delayed by reducing the Sr-content in the PLD target. |
| Databáze: | OpenAIRE |
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