Buried unstrained germanium channels: a lattice-matched platform for quantum technology
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arXiv
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| Autori principali: | , , , , , , , , , , |
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| Natura: | Preprint |
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2025
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| author | Costa, Davide Del Vecchio, Patrick Hudson, Karina Stehouwer, Lucas E. A. Tosato, Alberto Esposti, Davide Degli Calvi, Vladimir Moreschini, Luca Lodari, Mario Bosco, Stefano Scappucci, Giordano |
| author_facet | Costa, Davide Del Vecchio, Patrick Hudson, Karina Stehouwer, Lucas E. A. Tosato, Alberto Esposti, Davide Degli Calvi, Vladimir Moreschini, Luca Lodari, Mario Bosco, Stefano Scappucci, Giordano |
| contents | Strained Ge ($ε$-Ge) and strained Si ($ε$-Si) buried quantum wells have enabled advanced spin-qubit quantum processors. However, in the absence of suitable lattice-matched substrates, $ε$-Ge and $ε$-Si are deposited on defective, metamorphic SiGe substrates, which may impact device performance and scaling. Here an alternative platform is introduced, based on the heterojunction between unstrained Ge and a lattice-matched strained SiGe ($ε$-SiGe) barrier, eliminating the need for metamorphic buffers altogether. In a structure with a 52-nm-thick $ε$-SiGe barrier, a low-disorder two-dimensional hole gas is demonstrated with a high-mobility of 1.33$\times$10$^5$ cm$^2$/Vs and a low percolation density of 1.4(1)$\times$10$^1$$^0$ cm$^-$$^2$. Quantum transport shows that holes confined in the buried unstrained Ge channel have a strong density-dependent in-plane effective mass and out-of-plane $g$-factor, pointing to a significant heavy-hole$-$light-hole mixing in agreement with theory. Measurements of Zeeman spin-split levels in quantum point contacts further highlight this character, showing a two-fold larger in-plane $g$-factor in Ge than in $ε$-Ge. The prospect of strong spin-orbit interaction, isotopic purification, and of hosting superconducting pairing correlations make this platform appealing for fast quantum hardware and hybrid quantum systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_04724 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Buried unstrained germanium channels: a lattice-matched platform for quantum technology Costa, Davide Del Vecchio, Patrick Hudson, Karina Stehouwer, Lucas E. A. Tosato, Alberto Esposti, Davide Degli Calvi, Vladimir Moreschini, Luca Lodari, Mario Bosco, Stefano Scappucci, Giordano Mesoscale and Nanoscale Physics Strained Ge ($ε$-Ge) and strained Si ($ε$-Si) buried quantum wells have enabled advanced spin-qubit quantum processors. However, in the absence of suitable lattice-matched substrates, $ε$-Ge and $ε$-Si are deposited on defective, metamorphic SiGe substrates, which may impact device performance and scaling. Here an alternative platform is introduced, based on the heterojunction between unstrained Ge and a lattice-matched strained SiGe ($ε$-SiGe) barrier, eliminating the need for metamorphic buffers altogether. In a structure with a 52-nm-thick $ε$-SiGe barrier, a low-disorder two-dimensional hole gas is demonstrated with a high-mobility of 1.33$\times$10$^5$ cm$^2$/Vs and a low percolation density of 1.4(1)$\times$10$^1$$^0$ cm$^-$$^2$. Quantum transport shows that holes confined in the buried unstrained Ge channel have a strong density-dependent in-plane effective mass and out-of-plane $g$-factor, pointing to a significant heavy-hole$-$light-hole mixing in agreement with theory. Measurements of Zeeman spin-split levels in quantum point contacts further highlight this character, showing a two-fold larger in-plane $g$-factor in Ge than in $ε$-Ge. The prospect of strong spin-orbit interaction, isotopic purification, and of hosting superconducting pairing correlations make this platform appealing for fast quantum hardware and hybrid quantum systems. |
| title | Buried unstrained germanium channels: a lattice-matched platform for quantum technology |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2506.04724 |