SURFACE-STRUCTURES AND GROWTH MODE OF THE CU SI(100)2X1 SURFACE DEPENDING ON HEAT-TREATMENT/

New surface structures of the Cu/Si(100) surface were found by low-ene rgy electron diffraction after quenching from 500 degrees C for Cu-dep osited 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 Cu /Si(100)2 x 1 surface at 500 degrees C is of the Volmer-Weber type and a part of the Cu atoms deposited on the surface diffuses into the hul k at 500 degrees C in addition to island formation on the surface. The Cu atoms diffused into the bulk are segregated to the surface by quen ching and the segregated Cu atoms form several superstructures dependi ng on cooling speed and annealing time. As a result, 2 X 2 + 6 X 2, 2 X 2 + 6 X 5, 2 X 2 + 6 X 5 + 10 X 5, and 2 X 2 + 10 X 5 structures app ear in the ranges of the Cu/Si 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 on e-to-one correspondences between surface structures and surface Cu con centrations. The growth mode and surface structures of the Cu/Si surfa ce are characterized by a large diffusion coefficient of interstitial Cu atoms in Si as similar to that of the Ni/Si surface.