Nanoscale patterning and deformation of soft matter by scanning probe microscopy

Abstract

In this work, atomic force microscopy (AFM) was used for the surface nanopatterning as well as to study the nanoscale deformation of soft, carbon-based thin films and polymeric (polyethylene terephthalate, PET) membranes. The process of the AFM nanolithography was realized by application of contact force pulses to the samples, using silicon rectangular cantilevers of relatively high spring constant (kc=11 N/m, nominal value).Simultaneously, AFM is functioned as a nanometrology instrument, for nanomechanical measurements of the applied force and pressure for plastic deformation of the surface, which were found to vary between 200 and 2500 nN and between 1 and 4 GPa, respectively. The derived data were cross-checked with the materials' nanomechanical properties, which were measured using depth-sensing Nanoindentation, and the limits of the possible applied forces were specified.During the herein presented AFM nanolithography, several types of well-defined shapes, like pits and lines, were made. The dimensions of the patterned structures were correlated with the nanolithography parameters (e.g. applied force). The contact mechanics for the formation of uniformly patterned surfaces are discussed, in terms of shape geometry and dimensions, which comprise the essential characteristics for advanced applications like “probe-based data storage”, where data storage capacity is determined by pattern dimensions, or preferential adsorption of biomolecules on a patterned surface.