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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2603.18753 |
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| _version_ | 1866908901254889472 |
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| author | Della Valle, Enrico Nigro, Arianna Bonacci, Miki Colonna, Nicola Hofmann, Andrea Schüler, Michael Marzari, Nicola Zardo, Ilaria Strocov, Vladimir N. |
| author_facet | Della Valle, Enrico Nigro, Arianna Bonacci, Miki Colonna, Nicola Hofmann, Andrea Schüler, Michael Marzari, Nicola Zardo, Ilaria Strocov, Vladimir N. |
| contents | Germanium-silicon-germanium (Ge/Si$_{x}$Ge$_{1-x}$) heterostructures have emerged as a promising platform for hole-spin quantum technologies and high-mobility electronics, where strain and quantum confinement strongly reshape the Ge valence bands. However, the momentum-resolved valence-band structure of buried strained Ge quantum wells has so far been inferred only indirectly. Here we use soft X-ray angle-resolved photoemission spectroscopy (SX-ARPES) to directly probe the electronic structure of strained Ge quantum wells embedded in SiGe barriers. We resolve strain-split and size-quantized valence subbands, determine their heavy-hole, light-hole and split-off composition, and measure the valence-band offset at the Ge/SiGe heterojunction. Comparison with ab initio calculations shows that an accurate description requires explicit inclusion of the confinement potential imposed by the SiGe barrier, which plays a decisive role in determining the dispersion, ordering and mixing of the hole states. Our results provide the first direct experimental picture of how strain and confinement determine the valence-band structure of Ge quantum wells, establishing a foundation for predictive modelling of hole-spin qubits and high-mobility devices based on group-IV heterostructures. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_18753 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Direct observation of strain and confinement shaping the hole subbands of Ge quantum wells Della Valle, Enrico Nigro, Arianna Bonacci, Miki Colonna, Nicola Hofmann, Andrea Schüler, Michael Marzari, Nicola Zardo, Ilaria Strocov, Vladimir N. Materials Science Germanium-silicon-germanium (Ge/Si$_{x}$Ge$_{1-x}$) heterostructures have emerged as a promising platform for hole-spin quantum technologies and high-mobility electronics, where strain and quantum confinement strongly reshape the Ge valence bands. However, the momentum-resolved valence-band structure of buried strained Ge quantum wells has so far been inferred only indirectly. Here we use soft X-ray angle-resolved photoemission spectroscopy (SX-ARPES) to directly probe the electronic structure of strained Ge quantum wells embedded in SiGe barriers. We resolve strain-split and size-quantized valence subbands, determine their heavy-hole, light-hole and split-off composition, and measure the valence-band offset at the Ge/SiGe heterojunction. Comparison with ab initio calculations shows that an accurate description requires explicit inclusion of the confinement potential imposed by the SiGe barrier, which plays a decisive role in determining the dispersion, ordering and mixing of the hole states. Our results provide the first direct experimental picture of how strain and confinement determine the valence-band structure of Ge quantum wells, establishing a foundation for predictive modelling of hole-spin qubits and high-mobility devices based on group-IV heterostructures. |
| title | Direct observation of strain and confinement shaping the hole subbands of Ge quantum wells |
| topic | Materials Science |
| url | https://arxiv.org/abs/2603.18753 |