Epitaxial growth and strain relaxation of MgO thin films on Si grown by molecular beam epitaxy

F. Niu*, A. L. Meier, B. W. Wessels

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

High quality epitaxial MgO thin films have been grown on Si (001) wafers by molecular beam epitaxy using SrTi O3 (STO) as a buffer layer. The STO buffer layer reduces both the large lattice mismatch of 23% and the large thermal mismatch of 520% between MgO and Si. X-ray diffraction (XRD) measurements indicate that the MgO film grown on the STO buffered Si is epitaxial with MgO (002) ∥Si (004) and MgO [110] ∥Si [002]. The full width at half maximum (FWHM) of MgO (002) rocking curve width Δω is 0.30° (out-of-plane), and the FWHM of MgO (202) φ angle scan width Δφ is 0.34° (in-plane) for a 155 nm thick film. Strain relaxation and growth mechanisms of the MgO film on Si were studied by in situ reflection high-energy electron diffraction (RHEED) analysis in combination with XRD and atomic force microscopy. The results indicate that the MgO first forms a pseudomorphic wetting layer and subsequently undergoes a Stranski-Krastanov transition to form three-dimensional coherent islands to relieve misfit strain. A decrease in the width of the RHEED spots with increasing MgO thickness is observed that is attributed to reduction of coherency strain. A smooth surface redevelops once MgO growth continues, which is attributed to island coalescence.

Original languageEnglish (US)
Pages (from-to)2586-2591
Number of pages6
JournalJournal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures
Volume24
Issue number6
DOIs
StatePublished - 2006

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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