The electrical and optical material properties of epitaxial Ge 1−x Sn x and Si y Ge 1−x−y Sn x are of high interest for novel device applications. However, the limited Sn solubility in Ge makes the epitaxial growth of Ge 1−x Sn x and Si y Ge 1−x−y Sn x challenging. Most of the literature describing the epitaxial growth is for Ge 2 H 6 and SnCl 4 as Ge and Sn precursors, respectively. A more recent publication deals with the epitaxial growth of high-quality Ge 1−x Sn x with the more conventional GeH 4 . In this manuscript, we compare the structural and optical material quality of Ge 1−x Sn x , epitaxially grown on Ge virtual substrates as a function of growth pressure, growth temperature, the choice of the carrier gas (H 2 or N 2 ) and the choice of the Ge precursor (GeH 4 versus Ge 2 H 6 ). The best material quality in terms of surface morphology and photoluminescence characteristics is obtained if GeH 4 is used as a Ge precursor. For Ge 1−x Sn x grown with Ge 2 H 6 and at atmospheric pressure, pyramidical defects can be seen and there is a risk for uncontrolled local Sn agglomeration. The pyramidical defects are not observed on Ge 1−x Sn x layers grown at reduced pressure, but the highest achievable substitutional Sn concentration is lower. No pyramidical defects are found for Ge 1−x Sn x layers grown with GeH 4 and the issue of uncontrolled local Sn agglomeration does not appear.

We review the technology of Ge 1−x Sn x -related group-IV semiconductor materials for developing Si-based nanoelectronics. Ge 1−x Sn x -related materials provide novel engineering of the crystal growth, strain structure, and energy band alignment for realising various applications not only in electronics, but also in optoelectronics. We introduce our recent achievements in the crystal growth of Ge 1−x Sn x -related material thin films and the studies of the electronic properties of thin films, metals/Ge 1−x Sn x , and insulators/Ge 1−x Sn x interfaces. We also review recent studies related to the crystal growth, energy band engineering, and device applications of Ge 1−x Sn x -related materials, as well as the reported performances of electronic devices using Ge 1−x Sn x related materials.

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