Epitaxy relationships between Ge-islands and SiC(0Â 0Â 0Â 1)

Reflection high-energy electron diffraction (RHEED) has been used to determine epitaxy relationships and in-plane orientations between Ge and SiC(0 0 0 1). Three monolayers of Ge have been deposited at 500 °C on a graphitized SiC (6√3 × 6√3)R30° reconstructed surface, this surface supporting epitaxial Ge island growth in a Volmer-Weber mode. Nucleation of relaxed Ge-islands gives rise to transmission electron diffraction patterns allowing to deduce that pure Ge grows according to only one epitaxy relationship Ge{1 1 1}//SiC(0 0 0 1). These {1 1 1}-Ge-islands have two in-plane orientations, a preferential one, Ge〈-1-12〉//SiC〈1-100〉 and a minority one, Ge〈-1-12〉//SiC〈10-10〉, deduced one from the other by a 30° rotation around the 〈1 1 1〉-Ge (or [0 0 0 1]-SiC) growth axis. Due to the three-fold symmetry of the {1 1 1}-Ge plane, each in-plane orientation is degenerated into two twin orientations, differing by a 180° angle around Ge〈111〉.