Influence of H2 on strain evolution of high-Sn-content Ge1−xSnx alloys

Ge 1- x Sn x films with Sn content of up to 12 % were grown on Ge substrates using magnetron sputter epitaxy. The Ge 0.88 Sn 0.12 film grown in a pure Ar atmosphere was fully strained with a compressive strain magnitude of approximately 1.5 %, while the films were partially relaxed when grown in an H 2 /Ar mixture. It was revealed that the film’s lattice constant was increased in the presence of hydrogen by enhancing Sn migration to the subsurface layers, leading to the relaxation. The strain along the depth was investigated by Raman spectra and found to decrease greatly from the bottom of the Ge 0.88 Sn 0.12 film to the top surface. Our results indicate that hydrogenation is a potential method for strain relaxation in high-Sn-content Ge 1− x Sn x films.