Effect of point defects on lattice constant in MgO thin film deposited on silicon(0 0 1) substrate

Ab initio method approach using ABINIT code

¹ Kanagawa Industrial Technology Center, Kanagawa Prefectural Government, 705-1 Shimo-Imaizumi, Ebina, Kanagawa 243-0435, Japan
² Department of Materials Science and Engineering, Ibaraki University, 4-12-1, Nakanarusawa, Hitachi, Ibaraki 316-8511, Japan
³ Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuda, Yokohama, Kanagawa 226-8503, Japan

^a satoru.kaneko@gmail.com

Received: 13 June 2011
Revised: 31 October 2011
Accepted: 4 January 2012
Published online: 23 April 2012

Abstract

Epitaxial magnesium oxide (MgO) thin films prepared on Si(0 0 1) substrates revealed the contraction of its lattice constants along both out-of-plane and in-plane directions. X-ray Diffraction (XRD) verified the epitaxial growth with the relation of MgO(1 0 0) parallel to Si(1 0 0) [cubic on cubic growth] with large lattice misfit of ~22% instead of the relation of MgO(1 1 0) parallel to Si(1 0 0) [45° rotation growth] with lattice mismatch of ~9%. Although the domain epitaxy explaining the cubic on cubic growth is preferred in terms of crystallography, structural stability is not considered in the concept of the domain epitaxy. In order to explain the contraction of lattice constant from point of view of structural stability, ab initio method was used to evaluate all-electron total energy, and optimal lattice constant was estimated with point defects in the MgO structure.