Abstract
Interactions between macroscopic objects are quite different from those between nano-scale ones. When the size of a device is reduced to micrometer or even nanometer level, quantum and surface effects appear. This thesis presented molecular dynamics simulation and experiments to investigate the phenomenon of adhesion among nano-objects and the adhesion enhanced by externally applied electrostatic field. As an example, the enhancement of adhesion between the gold-coated atomic force microscopy (AFM) tip and the gold-coated substrate due to the application of electrostatic field were studied.The Morse potential was employed in the molecular dynamics simulation, which governs the force interactions between gold atoms. The simulation model was composed of the gold-coated parts of the AFM tip and substrate, which was connected to the rest parts of AFM tip and substrate by the use of boundary conditions. The gold atoms were arranged in order according to face centric cubic (FCC) structure. The tip with the pyramidal shape was formed from 664 gold atoms, and the substrate with the cuboid shape was formed from 2400 gold atoms. An experimental study is conducted by using AFM that interacted with the substrate in order to prove the results of the molecular dynamics simulation. Finally, the results obtained from both molecular dynamics simulation and experiments showed that the electrostatic field could enhance the adhesion and the number of atoms transferred from the gold-coated AFM tip to the gold-coated substrate. In addition, the adhesion force and the number of atom transfer increased with the raise of bias voltage between the tip and the substrate.