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Hexagonal Ge/Si0.25Ge0.75 quantum wells: Prediction of quantization and light-emission strength

Abderrezak Belabbes1,2,*, Martin Keller2, Jürgen Furthmüller2, Silvana Botti3,2, and Friedhelm Bechstedt2

  • 1Department of Physics, Sultan Qaboos University, P.O. Box 36, PC 123, Muscat, Oman
  • 2Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany
  • 3Research Center Future Energy Materials and Systems, Interdisciplinary Centre for Advanced Materials Simulation, Faculty of Physics and Astronomy, Ruhr University Bochum, Universitätsstrasse 150, 44801 Bochum, Germany

  • *Contact author: abderrezak.belabbes@uni-jena.de
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Phys. Rev. B 112, 205304 – Published 24 November, 2025

DOI: https://doi.org/10.1103/3l5b-b8ry

Abstract

We investigate heterostructures composed of hexagonal Ge quantum wells embedded within hexagonal Si0.25Ge0.75 alloy layers, systematically considering variations in crystallographic orientation, well thickness, and external biaxial strain. This study employs density functional theory together with accurate functionals for calculations of the quasiparticle electronic structure. Overall, the heterostructures exhibit type-I band alignment, with the localization of electron and hole wave functions predominantly within the hexagonal Ge regions. The quantum confinement of both charge carrier types is determined by the orientation and thickness of the Ge layer for three different external strains. The results obtained can be interpreted within a rectangular potential-well model, with characteristic parameters derived from ab initio band structures of hexagonal Ge and Si0.25Ge0.75, as well as their strained multiquantum well structures, properly aligned via the branch point energies. Besides confinement energies and subbands, optical transition strengths are also discussed.

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Outline

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Phys. Rev. B 112, 205304– Published 24 November, 2025
  • Received 9 March 2024
  • Revised 30 August 2025
  • Accepted 31 October 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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