Highly Stable Spatio-Temporal Mechanical Characterization of Nanocontact between Sharp Tips Using Electrostatic Microactuator inside Transmission Electron Microscope

摘要

A microelectromechanical systems-in-transmission electron microscope (MEMS-in-TEM) setup was established to characterize mechanical properties of a nanostructure captured or generated between tips, while observing its shape and deformation. This setup achieved a stable actuation for several tens of minutes with sub-nm accuracy, and a precise TEM observation of 0.2 nm in spatial resolution. The displacements of a tip-moving actuator with and without the nanostructure were measured from TEM images; the difference between them indicates a force applied to the nanostructure. The force was obtained by multiplying the displacement difference with a spring constant of supporting beams of the tip. Here, we performed an approach-formation-retraction-fracture experiment of a gold nanocontact between tips under TEM observation over 10 min at the actuation speed of 0.1 nm/s. The force during the retraction-fracture process was measured. The maximum force was 66 nN due to the work hardening by the existence of dislocations. This setup will be a powerful tool to examine the role of atomic scale structure for the mechanical characteristics and the extremely-low-speed kinetics.