Driving forces for Ag-induced periodic faceting of vicinal Cu

Abstract

Adsorption of submonolayer amounts of Ag on vicinal Cu(111) induces periodic faceting. The equilibrium structure is characterized by Ag-covered facets that alternate with clean Cu stripes. In the atomic scale, the driving force is the matching of Ag(111)-like packed rows with Cu(111) terraces underneath. This determines the preference for the facet orientation and the evolution of different phases as a function of coverage. Both Cu and Ag stripe widths can be varied smoothly in the 3-30 nm range by tuning Ag coverage, allowing to test theoretical predictions of elastic theories. * Corresponding author. Electronic address:

Determination of the photoelectron reference plane in nanostructured surfaces

“…Previous STM and LEED studies show that annealing up to 700 K does not significantly influence the final stripe formation. This suggests that thermal equilibrium is reached and Cu-Ag alloying is not relevant [12,21,26].…”

“…In general, self-organization results in textured surfaces that expose different crystal planes. Examples are nanostripe arrays, which can be created by step decoration [8,9] and faceting of stepped surfaces [10][11][12][13]. On the other hand, for reasonable size distributions of nano-object arrays characterized by their electron confinement, angle-resolved photoemission (ARPES) appears to be a well-suited technique for addressing the electronic structure of individual nano-units.…”

“…For such a study we can use nanostructured systems with structural tunability, which can be obtained by adsorbate-induced periodic faceting of vicinal surfaces. In the presence of adsorbates, periodic phase separation of adsorbate-covered and adsorbate-free facets may arise, since particular crystal orientations offer better substrate/adsorbate lattice matching [11][12][13]. An advantage of adsorbate-induced faceting is that by varying the coverage we readily tune the hill-and-valley structure.…”

“…In this study, our tunable, striped system is created by deposition of submonolayer amounts of Ag on a vicinal Cu(111) surface [12,21,22]. The resulting system is characterized by alternating self-assembled nanostripes of Ag and Cu, both aligned along the step directions of the substrate (see figure 1), but with different crystal orientations.…”

“…The resulting system is characterized by alternating self-assembled nanostripes of Ag and Cu, both aligned along the step directions of the substrate (see figure 1), but with different crystal orientations. In fact, submonolayer deposition leads to Ag-covered step bunches, such that clean Cu facets are progressively depleted of steps, until Ag-free Cu areas become (111)-oriented stripes [12,21]. Consequently, the Ag coverage has a direct influence on both the Ag and Cu stripe widths and on the local angle of the clean Cu facet (see figure 1).…”