An in-situ TEM characterization of electron beam induced dislocation motion in a single-crystalline gold thin film

Abstract

Dislocation motions driven by electron-beam illumination were in-situ observed in a single-crystalline gold thin-foil specimen, under a medium-voltage transmission electron microscope operated at 200 kV. The dislocation motion characteristics were in-situ observed under the bright-field and weak-beam dark-field conditions. The structures formed through the dislocation motion were also characterized using bright−/dark-field imaging and high-resolution techniques. Two types of dislocation motions are concluded, where one type of motion left no apparent traces, and the other type left a clear trace of passage. The dislocation motions have jerky behaviors, and the motions are accelerated when the beam intensity is increased. The immobile trace structures left by the dislocation motions are identified to be twin structures oriented along the 〈111〉 crystal directions. The dislocation motion mechanism is discussed and the motion might be caused by the electron beam heating effect or the electron beam induced phonon effects. The dislocation disassociation, planar defect formation in the Au crystal, and the beam heating impacts are also discussed.