Scanning-tunneling-microscopy studies of the S-induced reconstruction of Cu(100)

This study utilizes Auger-electron spectroscopy, low-energy electron diffraction, and scanning tunneling microscopy (STM) to examine sulfur coverages above ${\mathrm{\Theta }}_{\mathit{S}}$=0.25 on the Cu(100) surface. These large sulfur coverages are observed to induce a restructuring of the copper surface through the removal of copper atoms from terrace sites. The layer produced at room temperature by ${\mathrm{H}}_2$S exposures is composed of small Cu-S aggregates which do not exhibit long-range order, but which orient in the [001] and [010] directions. Heating above 873 K causes tetramer sulfur unit cells to form in a poorly ordered overlayer. Annealing to 1173 K produces a well-ordered (√17 × √17 )R14° structure which shows four sulfur atoms per unit cell in the STM images. Since the sulfur coverage of the (√17 × √17 )R14° structure has been previously measured to contain a total of eight sulfur atoms per unit cell, a structural model is proposed that is consistent with the coverage and STM measurements.