Growth of Ge1 − xSnx heteroepitaxial layers with very high Sn contents on InP(001) substrates

We investigated the crystalline structures of Ge1 − xSnx heteroepitaxial layers with Sn contents greater than 20% grown on InP and Ge substrates. Considering the lattice mismatch between the Ge1 − xSnx layers and the substrates, we achieved epitaxial growth of Ge1−xSnx layers with very high Sn content by suppressing the Sn precipitation; in addition, we improved upon the crystalline quality of Ge1 − xSnx heteroepitaxial layers. As a result, we could successfully form a 130 nm-thick Ge1 − xSnx heteroepitaxial layer on an InP substrate with a Sn content as high as 27% without Sn precipitation. We also improved the crystalline quality of Ge1 − xSnx layers by annealing at a temperature as low as 290 °C.

► Heteroepitaxial growth of a Ge1 − xSnx layer on InP with a Sn content as high as 27%.
► Lattice mismatch is a key to obtain Ge1 − xSnx layers with Sn content over 20%.
► Usefulness of annealing to improve on Ge1 − xSnx crystallinity is demonstrated.