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 degrees 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 10(11) cm(-2) to 10(10) 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. (C) 2015 Elsevier B.V. All rights reserved.