The Au/Si(111) interface: Growth mode, energetics, structural and electronic properties

Abstract

The Au/Si(111) interface is of major practical interest in semiconductor technology. As a consequence recent experimental investigations have been devoted to its characterization. The growth mode has been followed by AES. At room temperature the interface is diffuse: a mixed compound amorphous in structure, with composition close to the eutectic one is formed prior to the development of gold layers. Yet the topmost surface layer (even for ∼100 gold layers deposited) is a silicon rich surface phase showing peculiar electronic properties in AES, ELS and UPS. At high temperatures (⪆400°C) the growth of Au follows the Stranski-Krastanov mechanism: three-dimensional gold crystallites in parallel epitaxy grow after the completion of a silicon rich surface layer showing a 6 × 6 structure in LEED patterns. However, in the submonolayer range two surface phases are previously formed: a Si(111) 5 × 1−Au one completed at θ = 2/5 and a Si(111) √3 × √ − R30° − Au one completed at θ = 1. Isothermal desorption kinetics experiments yield quantitative data on the energetics of all surface phases involved.