2017/05/01 by A V Bubis, A. V. Bubis, A O Denisov +15 · 7 citations
Engineering · Physics and Astronomy · #Charge-carrier density #Diffusion #Gate voltage #Nanowire #Nanowire Synthesis and Applications #Proximity effect (electron beam lithography) #Quantum and electron transport phenomena #Reduction (mathematics) #Semiconductor Quantum Structures and Devices #cond-mat.mes-hall
paper · pdf · doi:10.1088/1361-6641/aa7eef
published in Semiconductor Science and Technology 32(9), 094007 (IOP Publishing)
arxiv created 2017/05/01 · openalex created_date 2017/05/12 · openalex publication_date 2017/07/11 · arxiv updated 2017/09/25 · openalex updated_date 2026/08/05
Abstract 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 V g . At high positive V g the devices feature transport signatures characteristic of diffusive junctions with highly transparent interfaces—sizable excess current, re-entrant resistance effect and proximity gap values ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) close to the Al gap ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> </mml:math> ). At decreasing V g , we observe a reduction of the proximity gap down to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> </mml:msub> <mml:mo>≈</mml:mo> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy="true">/</mml:mo> </mml:mrow> <mml:mn>2</mml:mn> </mml:math> at NW conductances <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mn>2</mml:mn> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">e</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width="0.25em"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">h</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> , which is interpreted in terms of carrier density dependent reduction of the Al/InAs interface transparency. We demonstrate that the experimental behavior of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Δ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>N</mml:mi> </mml:mrow> </mml:msub> </mml:math> is closely reproduced by a model with rectangular potential barrier at the Al/InAs interface.