LINKING DISLOCATION DYNAMICS AND CHEMICAL-REACTIVITY ON STRAINED METAL-FILMS

The interaction of a model strained metal film with oxygen is studied by scanning tunneling microscopy. Two monolayers of copper on Ru(0001) present a well-defined dislocation network composed of threading disl ocations and Shockley partial dislocations separating areas of fee and hcp stacking. We find that oxygen first reacts with these threading d islocations. Then, for exposures up to similar to 0.4 L-O2, new thread ing dislocation arrays appear on the surface. With the addition of mor e oxygen, the mesoscopic structure of the film changes from a striped array of Shockley partials to a disordered array of triangular fee reg ions bounded by dislocations, as oxygen proceeds to etch away the hcp areas of the copper film. (C) 1998 Published by Elsevier Science B.V. All rights reserved.