Ordered nucleation of Ni and Au islands on Au(111) studied by scanning tunneling microscopy

The scanning tunneling microscope reveals that Ni deposited on Au(111) at room temperature forms regular arrays of two-dimensional islands. The islands grow with spacing 73 Å in rows 140 Å apart at sites determined by the Au(111) ‘‘herringbone’’ reconstruction. This nucleation at evenly spaced sites yields islands with a narrow size distribution. The apparent Ni island height (1.9 Å) is bias-independent and agrees with a hard-sphere model of pseudomorphic Ni/Au(111). The behavior of Ni is contrasted with Au deposited on Au(111), for which far fewer islands are formed.