Isothermal Heteroepitaxy of Ge Sn Structures for Electronic and Photonic Applications.

Epitaxy of semiconductor-based quantum well structures is a challenging task since it requires precise control of the deposition at the submonolayer scale. In the case of Ge Sn alloys, the growth is particularly demanding since the lattice strain and the process temperature greatly impact the composition of the epitaxial layers. In this paper, the realization of high-quality pseudomorphic Ge Sn layers with Sn content ranging from 6 at. % up to 15 at. % using isothermal processes in an industry-compatible reduced-pressure chemical vapor deposition reactor is presented. The epitaxy of Ge Sn layers has been optimized for a standard process offering a high Sn concentration at a large process window. By varying the N carrier gas flow, isothermal heterostructure designs suitable for quantum transport and spintronic devices are obtained.