McLoughlin, E;Cafolla, AA;AlShamaileh, E;Barnes, CJ

SURFACE SCIENCE

A re-interpretation of the Cu{100}/Sn surface phase diagram

2001

June

Published

1

24 ()

GROWTH MONOLAYERS CU(111) SN PD

1431

1439

The coverage dependent structural phase transitions of Sn on Cu{100} have been re-examined by low energy electron diffraction (LEED). Double scattering LEED pattern simulations have been applied both to a range of possible new models and to previously suggested structures with the aim of identifying the most likely surface geometries throughout the sub-monolayer coverage regime. A model consistent with both the Sn surface coverage and the complex split beam LEED pattern observed has been suggested for the low coverage (theta (sn) = 0.21 ML) ordered phase based on a p(2 x 2) structure with "light" antiphase domain walls. We also demonstrate that higher coverage p(2 x 6) (theta (Sn) = 0.37 ML) and p(3 root2 x root2)R45 degrees (theta (Sn) = 0.50 ML) structures based on c(2 x 2) local periodicity yield a consistent explanation of the LEED data. While the simulations identify likely structures, the limitations of this approach mitigate against definitive structural assignments. However simulations for models based on c(2 x 2) structures incorporating defects in the form of periodic density modulations combined with substrate reconstruction lead to an enhanced agreement with observed LEED data compared to overlayer models previously suggested. (C) 2001 Elsevier Science B.V. All rights reserved.