Positron diffraction study of SiC(0Â 0Â 0Â 1) surface

Surface structures of 6H SiC(0 0 0 1) after heat treatment in a UHV has been studied using reflection high-energy positron diffraction (RHEPD). After heat treatment at 900 °C, a typical interference effect of positron waves due to Si adatoms appears in the total reflection region of the rocking curve. The further heat treatment at 1100 °C results in surface graphitization. The rocking curve is well reproduced by theoretical calculation assuming the graphite monolayer on SiC substrate. The interlayer distance is fairly large (2.5-3.2 Å), which is comparable to that in the graphite monocrystal suggesting that the weak binding of the graphite monolayer to the SiC surface by the van der Waals force.