Studying interfaces on a nm scale by BEEM

Abstract

Ballistic electron emission microscopy is a technique derived from scanning tunnelling microscopy and allows the investigation of the electrical and structural properties of metal/semiconductor and semiconductor/semiconductor interfaces on a small scale. In our experiments on thin (2–3 nm) metallic CoSi 2 films grown epitaxially on Si(111), we have studied the distribution of point defects at the interface. They tend to accumulate within the core of partial dislocations. The lowered density of point defects found close to dislocations is explained by diffusion and subsequent trapping during an annealing step. Ballistic electron emission spectroscopy performed on a single point defect was used to identify the contrast mechanism. A current contribution of k ‖ conserving processes with a delayed onset is much less affected by the presence of a point defect than a current component due to electrons scattered at the interface, which shows a strong enhancement.