Friction dependence on growth conditions in epitaxial films

In investigating the growth kinetics of epitaxial films in situ by force microscopy, we have observed several instances where the lateral force contrast on the growing monolayer exhibits a strong dependence on the driving force for growth (i.e., solute concentration). We present results for three epitaxial growth systems in aqueous solutions: CaSO(3) on CaCO(3), PbSO(4) on BaSO(4), and BaSO(3) on BaSO(4). In each system, material grown at higher solute concentrations exhibits a friction higher than that of material grown at lower concentrations. These observations suggest a link between defect density and friction contrast in growing epitaxial films. An additional time-dependent behavior is observed in the CaSO(3)/CaCO(3) system, indicating an annealing process.