Nanoscale growth of silver on prepatterned hydrogen-terminated Si(001) surfaces

Abstract

Silver (Ag) growth on H-terminated Si(001) surfaces with prepatterns of silicon (Si) dangling bonds has been studied at room temperature using a scanning tunneling microscope (STM). The patterns were fabricated by extraction of hydrogen (H) atoms from a H-terminated Si(001)-(2\ifmmode\times\else\texttimes\fi{}1) surface with a STM tip. The study covers four different patterns: growth on H-terminated Si(001) surfaces with (1) an isolated single dangling bond site, (2) a dangling bond wire $(\ensuremath{\sim}1$ nm wide), (3) a dangling bond area $(20\ifmmode\times\else\texttimes\fi{}20$ ${\mathrm{nm}}^{2}),$ and (4) a dangling bond array. Ag adatoms readily diffuse on the surface and preferentially stick to patterns of dangling bonds. Ag adatoms are not spontaneously substituted for H atoms around the Ag adsorption sites. The behavior of Ag growth is different in each case. An isolated single dangling bond site can be occupied by an isolated single Ag atom or a Ag cluster. The dangling bond wire is covered by an Ag island of 1 monolayer (ML) in height. On the dangling bond area, Ag atoms preferentially stick to the edge of the area and a Ag island 1 ML in height grows in the direction perpendicular to the dimer rows. The behavior of each growth pattern is explained by the difference in binding energy of diffusing adatoms on H-terminated areas and Si dangling bond sites.