Surface structure of Cu/Si(111) at high temperature

Abstract

The epitaxial growth and the structure of Cu on Si(111)7 × 7 deposited at high temperature (< 300–600°C) was investigated mainly by medium energy ion scattering (MEIS) and scanning tunneling microscopy (STM). The domain images whose periodicity is about 5.5 ± 0.2 times of the Si bulk unit were observed at high sample bias (VS = 2.5 V). The periodicity coincides with the ‘5 × 5’ incommensurate structure that was observed by reflection high energy electron diffraction (RHEED). The ratio of dark to bright area of ‘5 × 5’ was estimated to guess the Si surface structure in the ‘5 × 5’ incommensurate layer after counting the number of Si atoms. The ratio was about 0.83 and there are about 1 monolayer of Si atoms in the incommensurate layer. The structure of the Si bulk that is just beneath the incommensurate layer might be the double layer and the first layer of the Si bulk might be relaxed inward by 0.01 nm after the measurements of the blocking profiles by MEIS.