Theoretical study of the formation of a GaAs bilayer on Si(111)

• Published in: Computational materials science 2012-09, Vol.62, p.216-220
• Main Authors: Ramírez Torres, Alfredo, H. Cocoletzi, Gregorio, Vázquez-Nava, R.A., López-Fuentes, M., Takeuchi, Noboru
• Format: Article
• Language: English
• Subjects: 2D Nanostructure; Adsorption; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Density functional theory; Exact sciences and technology; Gallium; Gallium arsenide; Gallium arsenides; Materials science; Mathematical analysis; Methods of deposition of films and coatings; film growth and epitaxy; Monolayers; Physics; Reconstruction; Silicon; Solid surfaces and solid-solid interfaces; Surface chemistry; Surface structure and topography; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of film growth
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2012.05.043

► We have modeled adsorption of As and Ga over Si(111) surface. ► A monolayer of As atoms substitutes the topmost Si(111) layer. ► At monolayer coverage Ga atoms forming zigzag atomic wires. ► We have compared the relative energy through the thermodynamic potential. ► Adsorption of 1ML of As is the most stable structure over all allowed values of Δμ. We have performed first principles total energy calculations, within the density functional theory, to investigate the formation of a GaAs bilayer on the Si(111) surface. For the exchange–correlation energies we have used the generalized gradient approximation, while the electron–ion interactions were treated using ultrasoft pseudo-potentials. We have first studied the adsorption of As and Ga atoms on the Si(111) surface. A monolayer of As atoms substitutes the topmost Si layer forming an almost ideally bulk terminated configuration. On the other hand, the adsorption of 1/3ML of Ga results in the formation of a √3×√3 reconstruction, with Ga atoms occupying T4 sites. The deposit of 1/3ML of Ga atoms on the As terminated Si(111) surface also results in the occupation of T4 sites. However, at full monolayer coverage, the Ga atoms occupy near top sites and form one dimensional atomic chain.