A theoretical investigation of adsorbate-induced surface relaxation effects using cluster models: Al on Si(111)

• Published in: Surface science 1997-05, Vol.380 (2), p.283-292
• Main Authors: Kairys, Visvaldas, Head, John D.
• Format: Article
• Language: English
• Subjects: Ab initio quantum chemical methods and calculations; Aluminum; Chemisorption; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Low index single crystal surfaces; Physics; Silicon; Solid-fluid interfaces; Surface relaxation and reconstruction; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(97)01577-X

Differently sized cluster calculations are used to investigate theoretically the preferred adsorption site for an Al adatom on the Si(111) surface. By performing partial geometry optimizations at the Hartree-Fock level on AlSi n subclusters around the site of interest we find significant Al adatom-induced surface relaxation effects distorting the Si atoms from their bulk lattice positions. The largest relaxation effects take place at the T 4 site resulting in Al adsorption at the T 4 site to be 5 kcal/mol more stable than at the H 3 site and considerably more stable than adsorption at the T 1 site. However, we only have confidence in this result after performing for the T 4 site a partial geometry optimization on the AlSi 5 subcluster in the AlSi 26H 24 cluster and by including appropriate correlation corrections.