The Effect Of The Contact Plastic Deformation On Topography Measurement In Atomic Force Microscope

Atomic force microscopy (AFM) plays an important role in the field of scientific research because of its excellent performance and simple operation, which has promoted the development of nanotechnology. Compared with other microscopy, the characteristic of AFM is that the AFM uses a cantilever probe to explore morphology.In previous papers, energy dissipation of AFM in the tapping mode caused by fluid bridge had been described in detail, and dynamic generation process of liquid bridge between probe and sample had been analyzed, it is very important to understand the adhesion force. Then, we get the liquid bridge generation model and calculate the dissipative energy caused by fluid bridge in tapping mode. On this basis, we focus on other factors that may cause the artifact.According to the study of micro scale contact problem, we proposed that the plastic deformation of sample can also cause the artifact. As for the effect under the different environment, how important and how to eliminate the influence is core work of this paper.Firstly, we use the micro scale contact theory to establish the loading’ unloading model, that is to say, the loading process is C-P model and unloading process is JKR model, then we use this simplified model to calculate the plastic dissipation power. Secondly, we use the finite element model to calculate the plastic dissipation power without considering the effect of surface adhesion. Through the comparison, the hypothesis proposed in this paper can be proved. Under the microscale contact, the surface adhesion can be neglected when we calculate the energy dissipation of plastic deformation.As we know, when the AFM contact model works in atmospheric environment, the capillary force is dominant in all of the adhesion forces. It is necessary to analyze the contribution of capillary force and plastic deformation to the contact dissipation energy. Through the calculation, the plastic dissipation ratio is much less than capillary force dissipation in tapping mode. At last, the vibration theory is used to analyze the effect of the energy dissipation in AFM vibration system in briefly.