|M.Sc Student||Bessler Ron|
|Subject||Electrical and Mechanical Properties of Bilayer Graphene|
|Department||Department of Nanoscience and Nanotechnology||Supervisor||Dr. Elad Koren|
|Full Thesis text|
The discovery of graphene has paved the way for numerous possibilities for new and novel inventions in the scientific community. This is attributed to graphene’s superior electrical, thermal, mechanical and optical properties.
The interlayer relative dielectric constant of 2-dimensional (2D) materials systems in general, and graphitic materials in particular, is one of their most important physical parameters, especially for electronic applications. Understanding of the dielectric response of few layers graphene is crucial to fully address its exotic electronic properties such as tunable band gap, superconducting-insulating transition, Coulomb drag etc.
In this thesis, I will present our study on electromechanical actuation of nano-scale graphitic contacts using atomic and lateral force microscopy. We show that besides the adhesive forces there are additional restoring electrostatic forces which scale parabolically with the potential drop across the sheared interface. Considering that the sheared interface comprises of weakly coupled 2D graphene sheets, similar to a parallel plate capacitor, such scaling law indicates that the measured electrostatic forces has a capacitive origin. We use this phenomenon to measure the intrinsic dielectric constant of the bilayer graphene interface i.e. 6 , which is in perfect agreement with recent theoretical predictions for multi-layer graphene structures. In addition, we investigated how the sliding velocity can affect various mechanical interlayer forces such as the adhesion and friction forces. We find that the adhesion increases while friction decreases with the increased velocity. Using Fast Fourier Transform analysis, the hopping distance can be observed, showing an increase in the hoping distance with the increase of velocity. Using a Force Field model simulations, we explain our observations by a sub-angstrom changes in the interlayer spacing upon the change in sliding velocity.
Our method can be generally used to extract the dielectric and mechanical properties of 2D materials systems and interfaces and our results pave the way for utilizing graphitic and other 2D materials in electromechanical-based applications