Growth and stability of rocksalt Zn1−xMgxO epilayers and ZnO/MgO superlattice on MgO (100) substrate by molecular beam epitaxy

Zn1−xMgxO films with x = 0.04–0.50 grown on MgO (100) substrates by molecular beam epitaxy retain the rocksalt (rs) crystal structure and grow epitaxially for x ≥ 0.17. In addition, the rs-ZnO epilayer is observed to be stable up to a thickness of 5 nm and also in a ZnO/MgO superlattice sample. Howe...

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Bibliographic Details
Published in:The Journal of chemical physics 2016-06, Vol.144 (21), p.214704-214704
Main Authors: Lu, C.-Y. James, Tu, Y.-T., Yan, T., Trampert, A., Chang, L., Ploog, K. H.
Format: Article
Language:English
Subjects:
Crystal growth
Crystal structure
Distortion
Epitaxial growth
Magnesium oxide
Molecular beam epitaxy
Physics
Substrates
Superlattices
Transformations
Wurtzite
Zinc oxide
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Summary:Zn1−xMgxO films with x = 0.04–0.50 grown on MgO (100) substrates by molecular beam epitaxy retain the rocksalt (rs) crystal structure and grow epitaxially for x ≥ 0.17. In addition, the rs-ZnO epilayer is observed to be stable up to a thickness of 5 nm and also in a ZnO/MgO superlattice sample. However, a portion of the superlattice has transformed to wurtzite (wz)-structure islands in a self-accommodated manner during growth. The transformation is a combination of a Bain distortion, an in-plane rotation of 14.5°, and a Peierls distortion, resulting in an orientation relationship of ( 100 ) rs / / ( 10 1 ̄ 0 ) wz and 〈 011 〉 rs   ∼ / / 〈 1 ̄ 2 1 ̄ 3 〉 wz . In such a manner, the volume expansion is only necessary along the growth direction and the in-plane strains can be minimized. A negative pressure generated during the transformation of ZnO stabilizes the MgO into a wurtzite structure.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4950885