(705d) Self and Directed Assembly of Metallic Nanostructures Via the Dewetting and Transport of Metallic Thin Films: Experimental and Theoretical Results
Self?organizing materials offer the potential to assemble complex systems by defining only the initial and bounding conditions if the fundamental scientific principles guiding the assembly are known. Liquid phase, thin film dewetting constitutes one such phenomenon whereby nanoscale thin films collectively assemble into complex microscale patterns in response to applied thermal energy. In general, dewetted films at equilibrium exhibit characteristic nanoparticle sizes and spacings as well as microscopic spatial correlations indicative of the capillary and liquid?solid forces at work.
Multiple iterations of nanosecond laser pulses followed by electron microscopy have made it possible to access the time evolution of patterned, dewetted films. Nanoscale nickel and copper lines, circles, rings and waves were prepared for laser irradiation by electron beam lithography, sputter deposition and subsequent lift?off. Capillary forces as well as liquid?solid interactions contribute to the final dewetted structure. The contributions of these forces to the final pattern were determined for a host of configurations using the combined approach of experiment and simulation. For the latter, classical Molecular dynamics simulations were carried out in the solid and liquid state so as to gauge, by direct comparisons with experimental measurements (de-wetting angle and velocity), what is the role that solid and liquid transport play in the de-wetting process.