Interaction of passivated clusters in solution with micro-patterned surfaces: guided flow versus defect pinning

Gold nanoclusters, chemically passivated with decanethiol and dissolved in toluene, have been deposited from solution onto selected regions of oxidize d silicon (100) surfaces patterned either with photoresist or an etched ste p. When the perimeter of a droplet crosses the boundary between the resist and the silicon surface, we observe transport of cluster solution along suc h discontinuities, outside of the droplet. Such guided flow can extend for over 600 mum across the surface, producing cluster chains as narrow as simi lar to 120 nm, once the toluene has evaporated. The same experiment with an etched step produces no transport of clusters, but rather selective deposi tion and growth around the discontinuity. These different responses are att ributed to the step/boundary material-principally its interaction with the toluene solvent during evaporation.