Atomic Scale Investigation on Nano Adhesive Contact Characteristics and Generation Mechanism for Single Crystal Si Surface with Graphene Films

This research reveals the generation mechanism of adhesion during contact process. The results show that the graphene layer numbers on Si surface are positively correlated with load-bearing capacity improvement of mechanical properties for Si substrate. Additionally, with graphene layer numbers increase, an anti-adhesion effect occurs on Si devices surface.

That is, Compared with numbers of silicon substrate with coated graphene layers, the numbers of adhesive contact atoms are reduced by 3.47 times than pure Si, it improves the interface contact performance significantly. The adhesive mechanism of graphene-coated films on Si is that high stress is concentrated on closely contact area between tip and Si substrate, which intensifies the strain localization degrees, resulting in the damage of the bond energy of silicon-silicon atoms and generating an adhesive effect.

Furthermore, as numbers of graphene layers increases, the distribution of stress concentration on closely contact area decreases, and the adhesion effect weakens accordingly. However, as the service temperature increases from extremely low to high, the adhesion effect gradually intensifies. The research also indicates that the higher the binding energy coefficient, the stronger the Si device with load-bearing capacity.

However, during loading, the amplitude of shear deformation and atomic displacement on closely contact area becomes more intense, and the adhesion effect becomes more prominent.