Epitaxy relationships between Ge-islands and SiC(0 0 0 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 8C on a graphitized SiC (6H3 6H3)R308 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, Geh-1-12i//SiCh1-100i and a minority one, Geh-1-12i//SiCh10-10i, deduced one from the other by a 308 rotation around the h1 1 1i-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 1808 angle around Geh111i.