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A.G. Fedorus, A.A. Mitryaev, A.G. Naumovets
Surface Science, Volume 606, Issues 5–6, March 2012, Pages 580-589
Institute of Physics, Natl. Academy of Sciences of Ukraine, Prospect Nauki 46, UA-03680, Kyiv-28, Ukraine
Abstract
Low-energy electron diffraction, Auger electron spectroscopy and contact potential difference methods have been used to study formation of Be overlayers on the Mo(1 1 2) and (0 1 1) surfaces in the temperature range from T = 78 K up to the beginning of Be desorption. At a coverage θ = 1, where θ is defined as the ratio between concentrations of adatoms and surface substrate atoms, overlayers were found to be pseudomorphic on both the substrates. Various types of close-packed Be structures were observed at θ > 1. Annealing of the Mo samples covered with Be caused not only overlayer ordering, but also a partial solution of Be in the near-surface layer of Mo and creation of a surface alloy. It is inferred that the work function changes, positive on Mo(1 1 2) up to 0.4 eV and negative on Mo(0 1 1) down to − 0.6 eV, are caused mainly by changes in surface roughness while the contribution of polarization of the Be Mo adsorption bond seems to be only minor.
