Growth of thin Ag islands on Ge(001)-2×1 surfaces below room temperature

Abstract

Germanium(001) surfaces deposited with less than 0.3 nm thick Ag on average were studied by scanning tunneling microscopy. After the small amount of Ag deposition at 100 K, thin two-dimensional (2D) islands with 0.18 nm height are predominantly found to elongate to the dimer-row direction on clean Ge(001)-2×1 surfaces. With increasing temperature during the deposition, the density of three dimensional (3D) islands with more than 0.6 nm height increases, although few 2D islands are still formed at room temperature. With increasing average thickness of deposited Ag, the density of 3D islands increases at any temperature between 100 K and 300 K. These features are explained in terms of the diffusion of Ag atoms on the surface during deposition.