Pollinger, F., Schmitt, S., Sander, D., Tian, Z., Kirschner, J., Vrdoljak, P., Stadler, C., Maier, F., Marchetto, H., Schmidt, T., Schöll, A., Umbach, E.
Nanoscale patterning, macroscopic reconstruction, and enhanced surface stress by organic adsorption on vicinal surfaces
New Journal of Physics 19, pp 013019/1-8 (2017)
Self-organization is a promising method within the framework of bottom-up architectures to generate
nanostructures in an efficient way. The present work demonstrates that self-organization on the length
scale of a few to several tens of nanometers can be achieved by a proper combination of a large (organic) molecule and a vicinal metal surface if the local bonding of the molecule on steps is significantly stronger than that on low-index surfaces. In this case thermal annealing may lead to large mass transport of the subjacent substrate atoms such that nanometer-wide and micrometer-long molecular stripes or other patterns are being formed on high-index planes. The formation of these patterns can be controlled by the initial surface orientation and adsorbate coverage. The patterns arrange self-organized in regular arrays by repulsive mechanical interactions over long distances accompanied by a significant enhancement of surface stress.Wedemonstrate this effect using the planar organic molecule PTCDA as adsorbate and Ag(10 8 7) and Ag(775) surfaces as substrate. The patterns are directly observed by STM, the formation of vicinal surfaces is monitored by high-resolution electron diffraction, the microscopic surface morphology changes are followed by spectromicroscopy, and the macroscopic changes of surface stress are measured by a cantilever bending method. The in situ combination of these complementary techniques provides compelling evidence for elastic interaction and a significant stress contribution to long-range order and nanopattern formation.