Formation of buried epitaxial Si-Ge alloy layers in Si (100) crystal by high dose Ge ion implantation

We have synthesized single crystal Si(1-x)Ge(x) alloy layers in Si group of zone axis (100) crystals by high dose Ge ion implantation and solid phase epitaxy. The implantation was performed using the metal vapor vacuum arc (Mevva) ion source. Ge ions at mean energies of 70 and 1000 keV and with doses ranging from 1(10)(exp 16) to 7(10)(exp 16) ions/sq cm were implanted into Si group of zone axes (100) crystals at room temperature, resulting in the formation of Si(1-x)Ge(x) alloy layers with peak Ge concentrations of 4 to 13 atomic percent. Epitaxial regrowth of the amorphous layers were initiated by thermal annealing at temperatures higher than 500 C. The solid phase epitaxy process, the crystal quality, microstructures, interface morphology, and defect structures were characterized by ion channeling and transmission electron microscopy. Compositionally graded single crystal Si(1-x)Ge(x) layers with full width at half maximum approximately 100nm were formed under a approximately 30nm Si layer after annealing at 600 C for 15 min. A high density of defects was found in the layers as well as in the substrate Si just below the original amorphous/crystalline interface. The concentration of these defects was significantly reduced after annealing at 900 C. The kinetics of the regrowth process, the crystalline quality of the alloy layers, the annealing characteristics of the defects, and the strains due to the lattice mismatch between the alloy and the substrate are discussed.