Conductance instabilities in quantum point contacts

J. C. Smith, C. Berven, M. N. Wybourne, S. M. Goodnick

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


We present low-temperature electron transport measurements on quantum point contacts defined by electrostatic constrictions in the two-dimensional electron gas of a GaAs/AlGaAs heterostructure. Infrared illumination and annealing reversibly changes the nature of the electron transport through the point contact, from ideal point contact behavior to transport that shows two-level conductance fluctuations. In the ideal case, the dependence of the differential conductance on the bias across the contact is used to determine the shape of the transverse confining potential. In the non-ideal case, current-controlled negative differential conductance in the device characteristic is observed, and is shown to be the average of a two-level random telegraph signal. The random telegraph signal consists of fluctuations between two well-defined differential conductance states. We suggest the fluctuations are due to changes in the transverse confining potential caused by the dynamics of DX centers in the AlGaAs near the point contact.

Original languageEnglish (US)
Pages (from-to)656-659
Number of pages4
JournalSurface Science
StatePublished - Jul 20 1996
Externally publishedYes


  • Electrical transport
  • Superconductor-semiconductor heterostructures

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


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