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Natural evolution of material nanostructuring is three-dimension ordering of nanoobjects. It opens an opportunity to create the artificial super crystals with adjusted optical, electronic, magnetic and etc. properties: The first step in this direction is creation and preservation of two-dimensional ordered nanostructures on a solid surface. When we are going to use such an ordering system in a technical devise we should pay attention to temporal stability of created nanostructures at ambient condition under room temperature.
For example, very interesting small metallic clusters, which demonstrate quantum-size effect, like quantum box, exist for a long time only at low temperature. To improve time stability of nanoclusters we use a combination of two effects: a) adsorbat patterning by two-dimensional superstructure and b) an exchange mechanism between adsorbat and substrate atoms. To prepare nanoclusters we use a self organized superlattice of dislocation loops on Ag/Cu(111) as a pattern and Cu deposition to stimulate an exchange mechanism and avoid surface diffusion of adsorbed atoms and clusters. During cooper deposition at 100K Ag atoms (due to smaller surface energy) go immediately up on top of just created Cu islands. Simultaneously Cu atoms go down and they incorporate in Ag monolayer.
STM study in ultra height vacuum shows that mobility of such bi-layer islands at room temperature drastically differs from mobility of metal cluster on clean Cu terrace. Our bi-layer islands exist up to 20 hours at room temperature, although they consist only of 20 atoms. STM images clearly show that exactly the dislocation loops serve as nucleation centers for bi-layer clusters. The observed shape and boundaries of bi-layer islands follow this pattern superlattice and, according to our model, are formed by heterogeneous interaction between Ag adsorbat and Cu substrate layers. STM study of bi-layer clusters destruction shows that they loose an upper Ag layer as the first stage.
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