Determination of buried dislocation structures by scanning tunneling microscopy

Using scanning tunneling microscopy on Cu/Ru(0001) thin films we have located the depth at which the cores of misfit dislocations lie below the film surface. The procedure is based on matching areas with unknown structure to areas with a known stacking sequence in the same film. Our results show that dislocations occur not only at the Cu/Ru interface, but also at various levels within the Cu films. Our analysis method should be applicable to the characterization of dislocation structures in other ultrathin film systems.