BROWNIAN-MOTION OF DISLOCATIONS IN THIN-FILMS

The motion of edge dislocations in a single monolayer film of Cu on Ru (0001) was studied by time-resolved scanning tunneling microscopy. The dislocations were observed to make rapid ID random walks in the film: This dislocation motion is attributed to the equilibrium thermal exch ange of atoms: between the solid film and the adatom gas covering the film. These results highlight a fundamental difference between the dyn amics of dislocations in thin films and the bulk, which is in principl e important in understanding the mechanical properties of thin films.