LEEM observation of formation of Cu nano-islands on Si(1 1 1) surface by hydrogen termination

The growth of Cu on Si(1 1 1) surface with and without hydrogen termination was studied with low energy electron microscopy. On the clean surface the two-dimensional “5×5” incommensurate layer is first formed followed by the formation of three-dimensional (3D) islands. On the hydrogen-terminated surface the formation of the “5×5” structure is suppressed and nano-scale 3D islands decorate the steps and domain boundaries of the δ7×7 structure. Many LEED spots from the nano-islands move with electron energy, which indicates that the islands are faceted. From the analysis of the LEED pattern it is suggested that the nano-islands are the (1 1 1)-oriented β-phase Cu–Si alloy and are terminated by (1 1 1), {5 5 4} and {15 16 13} faces.