Isothermal Heteroepitaxy of Ge_1–xSn_x Structures for Electronic and Photonic Applications

Abstract

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 Ge1–x Sn x 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 Ge1–x Sn x 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 Ge1–x Sn x layers has been optimized for a standard process offering a high Sn concentration at a large process window. By varying the N2 carrier gas flow, isothermal heterostructure designs suitable for quantum transport and spintronic devices are obtained.

Room Temperature Lattice Thermal Conductivity of GeSn Alloys

“…Due to the large lattice mismatch between Sn and Si, a Ge buffer layer was grown prior to the GeSn deposition to improve the crystal quality. Details on the epitaxy can be found elsewhere. , The Sn content and the layer thickness were extracted by fitting the Rutherford backscattering spectra ,, (not shown). The layer thickness of GeSn alloys of different stoichiometries was between 250 and 300 nm, except for the 12 at.% Sn, where a set of thicknesses, between 50 and 700 nm, was grown.…”