Structure and morphology of the as-polished diamond(111)-1×1 surface

We present an X-ray diffraction study of the polished, unreconstructed diamond (111) surface. By measuring the distribution of diffracted intensities along the (hk)=(10) crystal truncation rod, we have determined the structure of the unreconstructed surface. We find that after heating to 650 °C, the polished diamond(111)-(1 x 1) surface exhibits a single-bond cleavage plane terminated by hydrogen atoms and, for 15% of the surface area, by adsorbed oxygen, most likely in the form of hydroxyl groups. We observe relaxations in the first layers, most notably a 3% contraction between the first and second bilayer. AFM results are presented that confirm the morphology found in X-ray analysis. Medium-energy ion scattering was used to determine the oxygen coverage.