Realization of independent contacts in barrier-separated InAs/GaSb quantum wells

InAs/GaSb double quantum wells separated by a 100 Å AlSb middle barrier are grown by molecular beam epitaxy. We report a nanofabrication technique that utilizes the surface Fermi level pinning position in InAs [ E f s ( InAs ) ] for realizing independent electric contacts to each well. In particular...

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Bibliographic Details
Published in:Applied physics letters 2023-03, Vol.122 (12)
Main Authors: Wu, Xingjun, Wang, Jianhuan, Huang, Miaoling, Yan, Shili, Du, Rui-Rui
Format: Article
Language:English
Subjects:
Applied physics
Contact resistance
Depletion
Electric contacts
Epitaxial growth
Fermi surfaces
Gallium antimonides
Indium arsenides
Molecular beam epitaxy
Nanofabrication
Quantum wells
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Summary:InAs/GaSb double quantum wells separated by a 100 Å AlSb middle barrier are grown by molecular beam epitaxy. We report a nanofabrication technique that utilizes the surface Fermi level pinning position in InAs [ E f s ( InAs ) ] for realizing independent electric contacts to each well. In particular, separate Ohmic contacts to the upper InAs quantum well are achieved by selectively etching down to the InAs, while contacts to the lower GaSb quantum well are obtained by the depletion method. For the latter, the upper InAs quantum well is locally pinched off by top etched trenches capped with a remaining 2–3 nm InAs layer. As a result of a relatively low E f s ( InAs ), applying a negative bias gate potential will create a conducting hole channel in GaSb and, hence, a separate Ohmic contact to the lower quantum well. This method is demonstrated with experiment and the support of a self-consistent band bending calculation. A number of experiments on separately probing Coulomb and tunnel-coupled InAs/GaSb systems now become accessible.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0133795