Phase transition of Sr on Si (0 0 1): First principles prediction and experiment

• Published in: Surface science 2010-05, Vol.604 (9), p.857-861
• Main Authors: Garrity, Kevin F., Padmore, Myrtle-Rose, Segal, Yaron, Reiner, J.W., Walker, F.J., Ahn, C.H., Ismail-Beigi, S.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Density functional; Density functional theory; Diffraction; Epitaxial growth; Epitaxy; Exact sciences and technology; Grand canonical Monte Carlo; Lattice gas; Monte Carlo; Oxides; Phase diagrams; Physics; Reflection; RHEED; Silicon; Strontium
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2010.02.011

The ability to understand and predict the phase diagrams of surface phases from first principles can be valuable for developing processes for growth of epitaxial structures. In the growth of epitaxial oxides on Si (0 0 1), a submonolayer phase of Sr plays a key role. The physical structure for this phase, which has 2 × 3 symmetry and occurs at 1/6 monolayer Sr coverage, was recently elucidated using both first principles theory and diffraction experiments [J.W. Reiner, K.F. Garrity, F.J. Walker, S. Ismail-Beigi, C.H. Ahn, Role of strontium in oxide epitaxy on silicon (0 0 1), Phys. Rev. Lett. 101 (10) (2008) 105503.]. Our approach to understanding the broader Sr/Si phase diagram combines density functional theory with a thermodynamic analysis of the phase equilibrium between a Sr lattice gas and the 2 × 3 structure. We use reflection high energy electron diffraction (RHEED) to experimentally determine the phase diagram, finding good agreement with theoretical predictions.