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Understanding surface structure and chemistry of single crystal lanthanum aluminate

Lookup NU author(s): Dr Stevin Pramana

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© The Author(s) 2017. The surface crystallography and chemistry of a LaAlO3 single crystal, a material mainly used as a substrate to deposit technologically important thin films (e.g. for superconducting and magnetic devices), was analysed using surface X-ray diffraction and low energy ion scattering spectroscopy. The surface was determined to be terminated by Al-O species, and was significantly different from the idealised bulk structure. Termination reversal was not observed at higher temperature (600 °C) and chamber pressure of 10-10 Torr, but rather an increased Al-O occupancy occurred, which was accompanied by a larger outwards relaxation of Al from the bulk positions. Changing the oxygen pressure to 10-6 Torr enriched the Al site occupancy fraction at the outermost surface from 0.245(10) to 0.325(9). In contrast the LaO, which is located at the next sub-surface atomic layer, showed no chemical enrichment and the structural relaxation was lower than for the top AlO2 layer. Knowledge of the surface structure will aid the understanding of how and which type of interface will be formed when LaAlO3 is used as a substrate as a function of temperature and pressure, and so lead to improved design of device structures.


Publication metadata

Author(s): Pramana SS, Cavallaro A, Qi J, Nicklin CL, Ryan MP, Skinner SJ

Publication type: Article

Publication status: Published

Journal: Scientific Reports

Year: 2017

Volume: 7

Online publication date: 02/03/2017

Acceptance date: 27/01/2017

Date deposited: 06/04/2017

ISSN (electronic): 2045-2322

Publisher: Nature Publishing Group

URL: https://doi.org/10.1038/srep43721

DOI: 10.1038/srep43721


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