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

Abstract

An epitaxial Ge layer is grown by solid-phase epitaxy on an underlying Ge0.82Si0.18 seeding layer with a Ge-SiO2 matrix positioned between them. To this end, a (100)Si substrate with a Ge0.82Si0.18 epilayer is first oxidized in a wet ambient at 700 °C for 30 min to transform an upper fraction of the epilayer to amorphous Ge0.82Si0.18O2. 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 Ge0.82Si0.18 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 Ge0.82Si0.18 template.