Quasi-Static Frictional Test between Silicon Sharp Probes with in-situ TEM Observation of Real Contact Point

Abstract

Frictional deformation of a nano-scaled real contact area between silicon MEMS opposing tips was in-situ visualized by a transmission electron microscope and the force to deform the real contact area was simultaneously measured. In our experiment, the initial diameter of the real contact point was 6.4 nm. During the frictional motion at 0.01 nm/s, the force applied to the contact point was gradually increased. The maximum frictional force was 61 nN when the diameter of the real contact point was 2.2 nm. After the maximum force, the force gradually decreased to zero because the real contact point was retracted and finally fractured. The friction coefficient was 0.9, which is reasonable in comparison with the previous reports. This result suggested that the friction was caused by the deformation of the real contact point.