Regensburg 2022 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 22: Poster Monday: Surface Structure, Epitaxy, Growth and Tribology

O 22.8: Poster

Montag, 5. September 2022, 18:00–20:00, P4

Measuring energy dissipation on Si(111) with Lateral Force Microscopy (LFM) — •Thomas Holzmann, Shinjae Nam, Oliver Gretz, Alfred John Weymouth, and Franz Josef Giessibl — Universität Regensburg, Deutschland

In Lateral Force Microscopy (LFM), a cantilever is oscillated parallel to a sample surface at a set amplitude. The forces acting on such an oscillating cantilever are not necessarily conservative. The energy gain or energy loss can be position dependent, depending on the surface. We observed a strong lateral dependence of dissipation around adatoms of the 7x7-resconstruction of Si(111). We used LFM to measure this energy dissipation and applied different bias voltages between tip and sample, which changed the energy dissipation. Certain mechanisms, that contribute to energy dissipation, such as CO-bending (when using a CO-terminated tip) and chemical bonding should not be sensitive to changes in the bias voltage. Only the electrostatic part of the ineraction should be influenced by a change in the bias voltage. We developed a model to simulate the energy dissipation due to electrostatic forces similar to that proposed in Ondracek et al. Nanotechnology 27, 274005 (2016). In this model, electrons tunnel to a local quantum dot on the tip or sample before diffusing to the bulk. It can predict the area where the dissipation occurs. But surprisingly the dissipation signal changes its sign, depending on which side of the quantum dot the tip is located. Following this observation we looked at possible explanations for this behaviour.