Surface structures formed upon oxidation of the (311) face of copper

The oxidation of the copper (311) surface at temperatures from 25 to 900° C, and at oxygen pressures from 1 atm to 10⁻⁴ torr has been investigated by reflection high energy electron diffraction (RHEED). At room temperature, a poorly organized three-demensional epitaxial layer of Cu²O initially covers the surface, but it disappears when heated in vacuum to 200 °C. Between 300 and 600 °C, two symmetry-equivalent versions of a (4 × 1) two-dimensional surface structure form. Above 500 °C, this structure transforms into another having a hexagonal primitive cell with one axis coinciding with the Cu 011̄] direction and an axial length of 5.212 Å. This is the same cell which has been observed previously with oxidation of copper (100), (111), and (110) faces above 600 °C. Upon oxidation above 600 °C, the surface decomposes into (111) and (100) facets having the copper 010̄] direction in common.