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

Publication date: Available online 2 December 2015
Source:Thin Solid Films
Author(s): Shohei Kidowaki, Takanori Asano, Yosuke Shimura, Masashi Kurosawa, Noriyuki Taoka, Osamu Nakatsuka, Shigeaki Zaima
We have investigated the epitaxial growth and crystalline properties of Ge1-x Sn x 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-x Sn x /Si(110) samples. The degree of strain relaxation is enhanced by the annealing process, and the threading dislocation in the Ge1-x Sn x 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-x Sn x /Si interface, which would effectively promote isotropic strain relaxation in the Ge1-x Sn x layers.