Proximity effect and interface transparency in Al/InAs-nanowire/Al diffusive junctions

We investigate the proximity effect in InAs nanowire (NW) junctions with superconducting contacts made of Al. The carrier density in InAs is tuned by means of the back gate voltage Vg. At high positive Vg the devices feature transport signatures characteristic of diffusive junctions with highly tran...

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Bibliographic Details
Published in:Semiconductor science and technology 2017-09, Vol.32 (9), p.94007
Main Authors: Bubis, A V, Denisov, A O, Piatrusha, S U, Batov, I E, Khrapai, V S, Becker, J, Treu, J, Ruhstorfer, D, Koblmüller, G
Format: Article
Language:English
Subjects:
InAs nanowires
interface scattering
proximity effect
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Summary:We investigate the proximity effect in InAs nanowire (NW) junctions with superconducting contacts made of Al. The carrier density in InAs is tuned by means of the back gate voltage Vg. At high positive Vg the devices feature transport signatures characteristic of diffusive junctions with highly transparent interfaces-sizable excess current, re-entrant resistance effect and proximity gap values ( Δ N ) close to the Al gap ( Δ 0 ). At decreasing Vg, we observe a reduction of the proximity gap down to Δ N Δ 0 2 at NW conductances ∼ 2 e 2 h − 1 , which is interpreted in terms of carrier density dependent reduction of the Al/InAs interface transparency. We demonstrate that the experimental behavior of Δ N is closely reproduced by a model with rectangular potential barrier at the Al/InAs interface.
ISSN:0268-1242
1361-6641
DOI:10.1088/1361-6641/aa7eef