Determining the GaSb/GaAs-(2 × 8) reconstruction

• Published in: Surface science Vol. 603; no. 19; pp. 2945 - 2949
• Main Authors: Bickel, Jessica E., Modine, Normand A., Millunchick, Joanna Mirecki
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.10.2009; Elsevier
• 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 calculations; Exact sciences and technology; Molecular beam epitaxy; Physics; Surface relaxation and reconstruction; Molecular beam epitaxy; Density functional calculations; Surface relaxation and reconstruction; Gallium arsenides; Gallium antimonides; Inorganic compounds; Semiconductor materials; Binary compounds; Structure relaxation; Film growth; Surface structure; Surface reconstruction; Density functional method
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2009.07.044

Highly strained thin layers of GaSb/GaAs possess a (2 × 4) reconstruction at low Sb overpressures, and a (2 × 8) reconstruction at high Sb overpressures. While the atomic details of the Sb/GaAs-(2 × 4) are well known, the details of the (2 × 8) are not understood. In this paper, we use density functional theory to analyze possible (2 × 8) structures. Comparing scanning tunneling microscope images from both simulation and experiment and examining the relative energies of possible (2 × 8) structures, we show the α(2 × 8) and β(2 × 8) are the thermodynamically stable surface reconstructions for high Sb content films strained to the GaAs lattice parameter. The α and β(2 × 8) reconstructions are related to the GaAs-α2(2 × 4) and GaAs-β2(2 × 4) through the addition of 2 cations and 8 anions into the trench between adjacent (2 × 4) unit cells.