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

Abstract

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 1011cm−2 to 1010cm−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.