Nucleation of ordered Ni island arrays on Au(111) by surface-lattice dislocations

Scanning tunneling microscopy of Ni deposited on Au(111) at room temperature reveals strikingly ordered island nucleation. Ni islands grow with spacing 73 Å along [12¯1] in rows 140 Å apart at surface-lattice dislocations induced by the Au(111) ‘‘herringbone’’ reconstruction. The island arrays are explained by a model in which Ni atoms diffuse on the surface and aggregate at these dislocations. Island size varies by more than the shot-noise limit, suggesting that the initial sticking probability is low when a diffusing atom encounters a dislocation.