Carrier density dependent electric transport of serially connected two quantum point contacts

K. M. Liu, H. I. Lin, V. Umansky, Shih-ying Hsu*

*Corresponding author for this work

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

We have measured the electric transport of double quantum point contacts in series at low temperatures. Two pairs of metal gates are placed longitudinally and sequentially with an edge-to-edge distance of 600 nm. They are used to form two quantum point contacts in a GaAs / Alx Ga1 - x As heterostructure. Isolating from an insulating layer, a top gate is also fabricated on top of the quantum point contacts to modify the electron densities in the quantum point contacts and the two dimensional electron gas as well. The transport is characterized by the direct transmission probability Td which represents the portions of electrons travelling ballistically from one quantum point contact to the other. Our results show that the parameter Td decreases with decreasing carrier density. The transport is partially adiabatic in high 2D electron densities and transits to completely ohmic regimes in low densities. Because of the correlation between the coherence length and transmission probability, we attribute the result to the reduction of the coherence length and mean free path in the unconstricted electron gas between quantum point contacts.

Original languageEnglish
Pages (from-to)1122-1125
Number of pages4
JournalPhysica E: Low-Dimensional Systems and Nanostructures
Volume42
Issue number4
DOIs
StatePublished - 1 Feb 2010

Keywords

  • Adiabatic transport
  • Ohmic transport
  • Quantum point contacts in series
  • Transmission probability

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