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Ultrathin oxide films: CaO layers on BaO and SrO

Published online by Cambridge University Press:  01 February 2011

Chris E Mohn
Affiliation:
c.e.mohn@kjemi.uio.no, University of Oslo, Centre for Materials Science and Nanotechnology, Oslo, Norway
Neil L. Allan
Affiliation:
n.l.allan@bristol.ac.uk, University of Bristol, Chemistry, Bristol, United Kingdom
John H. Harding
Affiliation:
j.harding@sheffield.ac.uk, University of Sheffield, Engineering Materials, Sheffield, United Kingdom
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Abstract

Prompted by renewed interest in the crystalline oxides-on-semiconductors interface, periodic density functional theory and atomistic simulation techniques are used to examine the formation of a layer of CaO on a BaO substrate. We examine how CaO islands which form at coverages less than 100% adjust to the substrate in which the cation-anion separation is substantially larger than in CaO itself. All Ca-O bond lengths in the island are shorter than that in bulk CaO. Corner O atoms in the islands are associated with particularly short Ca-O bond lengths, and the shape of the islands is dominated by (100) edges. Once formed, islands with intact edges will remain intact. Interactions between islands at larger coverages are also investigated and we see the formation of characteristic elliptical gaps and loops.

Type
Research Article
Copyright
Copyright © Materials Research Society 2009

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