Dresden 2009 – scientific programme

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DS: Fachverband Dünne Schichten

DS 18: Layer Properties: Electrical, Optical and Mechanical Properties II

DS 18.3: Talk

Wednesday, March 25, 2009, 11:45–12:00, GER 37

Freestanding nanomembranes with adjustable stiffness from self-assembled monolayers — •Xianghui Zhang, Christoph T. Nottbohm, Andrey Turchanin, Andre Beyer, and Armin Gölzhäuser — Fakultät für Physik, Universität Bielefeld, Postfach 10 01 31, 33501 Bielefeld, Germany

We report on the fabrication and mechanical characterization of novel nanomembranes with a thickness of approximately 1 nm, whose stiffness is adjustable by an annealing treatment. The nanomembranes are prepared from electron cross-linked aromatic self-assembled monolayers (SAMs). Subsequent etching of the supporting substrate and transferring to window-structured substrates provides freestanding nanomembranes. Bulge testing within an atomic force microscope (AFM) is utilized to investigate their mechanical properties. To determine the Young’s modulus, the deformation of a nanomembrane is measured after applying a pressure to one side. Pristine membranes display elastic moduli ranging from 8 to 12 GPa, which are adjustable by the electron dose. After a thermal treatment in ultra high vacuum (UHV) they show a higher mechanical stiffness. Annealing gives rise to a systematic increase of the Young’s moduli from ∼10 GPa to ∼45 GPa for an annealing temperature of ∼1000 K. Strain relaxation lowers the residual strain from 0.9 % to ∼0.35 % for temperatures of 800 K and above. This indicates that the relevant structural transformation is completed at that temperature.