Defect and dislocation structures in low-temperature-grown Ge and Ge1 − xSnx epitaxial layers on Si(110) substrates

•Suppression of twin in GeSn growth on Si(110) substrate•Isotropic strain relaxation of Ge and GeSn layers by misfit dislocation network•Achievement of high quality GeSn epitaxial layers on Si(110) by post deposition annealing

We have investigated the epitaxial growth and crystalline properties of Ge1 − xSnx layers on a Si(110) substrate. We found that the twin growth in the Ge epitaxial layer deposited on the Si(110) using molecular beam epitaxy at a low temperature of 200 °C can be effectively suppressed by the incorporation of 2.0% Sn. We also examined the strain relaxation of annealed Ge1 − xSnx/Si(110) samples. The degree of strain relaxation is enhanced by the annealing process, and the threading dislocation in the Ge1 − xSnx layers decreases from 1011 cm− 2 to 1010 cm− 2 because of the propagation of misfit dislocations. We also observed misfit dislocations formed at the Ge1 − xSnx/Si interface, which would effectively promote isotropic strain relaxation in the Ge1 − xSnx layers.