Early stages of cesium adsorption on the As-rich c(2x8) reconstruction of GaAs(001) : adsorption sites and Cs-induced chemical bonds
Articolo
Data di Pubblicazione:
2003
Citazione:
Early stages of cesium adsorption on the As-rich c(2x8) reconstruction of GaAs(001) : adsorption sites and Cs-induced chemical bonds / C. Hogan, D. Paget, Y. Garreau, M. Sauvage, G. Onida, L. Reining. P. Chiaradia, V. Corradini. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 68:20(2003), pp. 205313.1-205313.11.
Abstract:
We investigate the adsorption of Cs on the As-rich $c(2\times 8)/(2\times 4)$
reconstruction of GaAs(001) at low coverages using a combination of
theoretical and experimental techniques. DFT-LDA total-energy calculations
and X-ray diffraction experiments find only minimal Cs-induced surface
relaxation and identify three preferential adsorption sites within the
partially disordered overlayer. These sites are, in order of decreasing
occupation probability, the arsenic dimer bridge D site, the gallium
dangling bond T$_{2}^{\prime }$ site and the arsenic T$_{3}$ trench site.
Detailed analysis of the wavefunctions and electronic charge densities
allows us to clarify the bonding mechanisms at the three sites.\ At the
gallium site, the bonding is strongly ionic and involves significant charge
transfer to a new Cs-induced state reminiscent of the $p_{z}$ orbital of the
gallium atom in the $sp^{_{2}}$ configuration. In sharp contrast, at the
arsenic sites, the charge transfer is minimal and the bonding rather occurs
through mixing with a relatively delocalized state of the clean surface. The
ionization energy decreases are estimated and compared for the three sites.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
adsorbed layers; caesium; dangling bonds; density functional theory; gallium arsenide; III-V semiconductors; surface energy; surface reconstruction; surface states; total energy; wave functions; X-ray diffraction
Elenco autori:
C. Hogan, D. Paget, Y. Garreau, M. Sauvage, G. Onida, L. Reining. P. Chiaradia, V. Corradini
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