Title
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Electron-hole superfluidity in strained Si/Ge type II heterojunctions
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Author
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Abstract
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Excitons are promising candidates for generating superfluidity and Bose-Einstein condensation (BEC) in solid-state devices, but an enabling material platform with in-built band structure advantages and scaling compatibility with industrial semiconductor technology is lacking. Here we predict that spatially indirect excitons in a lattice-matched strained Si/Ge bilayer embedded into a germanium-rich SiGe crystal would lead to observable mass-imbalanced electron-hole superfluidity and BEC. Holes would be confined in a compressively strained Ge quantum well and electrons in a lattice-matched tensile strained Si quantum well. We envision a device architecture that does not require an insulating barrier at the Si/Ge interface, since this interface offers a type II band alignment. Thus the electrons and holes can be kept very close but strictly separate, strengthening the electron-hole pairing attraction while preventing fast electron-hole recombination. The band alignment also allows a one-step procedure for making independent contacts to the electron and hole layers, overcoming a significant obstacle to device fabrication. We predict superfluidity at experimentally accessible temperatures of a few Kelvin and carrier densities up to similar to 6 x 10(10) cm(-2), while the large imbalance of the electron and hole effective masses can lead to exotic superfluid phases. |
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Language
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English
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Source (journal)
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npj Quantum Materials. - [S.l.]
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Publication
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[S.l.]
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Nature publishing group
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2021
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ISSN
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2397-4648
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DOI
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10.1038/S41535-021-00344-3
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Volume/pages
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6
:1
(2021)
, 7 p.
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Article Reference
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41
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ISI
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000642904200001
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Medium
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E-only publicatie
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Full text (Publisher's DOI)
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Full text (open access)
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