Ge epitaxial island growth on a graphitized C-rich 4H-SiC(0 0 0 1) surface

Abstract

Epitaxial Ge islands on a SiC(0 0 0 1) substrate have been examined by reflection high-energy electron diffraction (RHEED). These islands have been obtained by depositing three monolayers of Ge at 500 °C on a graphitized SiC (6√3×6√3)R30° reconstructed surface. This surface has been chosen for its ability to support epitaxial Ge island growth in a Volmer-Weber mode. The RHEED technique has allowed us to determine the epitaxy relationship and in-plane orientations between relaxed Ge and SiC(0001). Typical transmission electron diffraction patterns indicate that Ge grows according to only one epitaxy relationship Ge{1 1 1}||SiC(0 0 0 1) that corresponds to two in-plane orientations, a preferential one Ge 〈 1 ¯ 1 ¯ 2 〉 | | SiC 〈 1 1 ¯ 0 0 〉 and a minority one Ge 〈 1 ¯ 1 ¯ 2 〉 | | SiC 〈 1 0 1 ¯ 0 〉 rotated by 30° around the growth 〈1 1 1〉-Ge (or [0 0 0 1]-SiC) axis. Double spot RHEED patterns also point out a twinning for each in-plane orientation, a consequence of the three-fold order of the 〈1 1 1〉-Ge axis.