Ge epilayer of high quality on a Si substrate by solid-phase epitaxy

An epitaxial Ge layer is grown by solid-phase epitaxy on an underlying Ge_0.82Si_0.18 seeding layer with a Ge-SiO₂ matrix positioned between them. To this end, a (100)Si substrate with a Ge _0.82Si_0.18 epilayer is first oxidized in a wet ambient at 700°C for 30 min to transform an upper fraction of the epilayer to amorphous Ge_0.82Si_0.18O₂. A second annealing step (700°C/16 h) in a 95% N₂+5% H₂ ambient (forming gas) reduces the GeO₂ to Ge which grows epitaxially by solid-phase reaction on the remaining Ge_0.82Si_0.18 layer. A self-induced intermediate layer of epitaxial Ge with SiO₂ inclusions restricts the propagation of dislocations, resulting in a crystalline perfection of the overlying Ge epilayer superior to that of the Ge_0.82Si _0.18 template.