Surface scienceSurface structures and growth mode of the CuSi(100)2 × 1 surface depending on heat treatment

New surface structures of the CuSi(100) surface were found by low-energy electron diffraction after quenching from 500°C for Cu-deposited surfaces at 0.3 to 10 monolayers (ML). At room temperature, Cu was intermixed with Si and no defined interface structure was observed at coverages higher than a few ML. However, the growth mode in the CuSi(100)2 × 1 surface at 500°C is of the Volmer-Weber type and a part of the Cu atoms deposited on the surface diffuses into the bulk at 500°C in addition to island formation on the surface. The Cu atoms diffused into the bulk are segregated to the surface by quenching and the segregated Cu atoms form several superstructures depending on cooling speed and annealing time. As a result, 2 × 2 + 6 × 2, 2 × 2 + 6 × 5, 2 × 2 + 6 × 5 + 10 × 5, and 2 × 2 + 10 × 5 structures appear in the ranges of the CuSi Auger ratio between 0.05 and 0.08, 0.08 and 0.14, 0.14 and 0.18, and 0.18 and 0.2, respectively. There are one-to-one correspondences between surface structures and surface Cu concentrations. The growth mode and surface structures of the CuSi surface are characterized by a large diffusion coefficient of interstitial Cu atoms in Si as similar to that of the NiSi surface.