Transport in GaAs heterojunction ring structures

C. J.B. Ford, T. J. Thornton, R. Newbury, M. Pepper, H. Ahmed, G. J. Davies, D. Andrews

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


In earlier work we have shown that the split gate GaAsAlGaAs heterojunction FET has been a very useful system for obtaining 1D transport.1,2 We have now extended this work to the construction of ring structures. Here, a ring of resist (outside diameter 2.2μm, inside diameter 0.4μm) is formed on the AlGaAs surface using Electron Beam Lithography, and is covered with metal, thereby forming a Schottky gate inside and outside the ring. Application of a negative voltage to the gates depletes the high-mobility 2D electron gas at the interface, except in a narrow annulus between the gates. The width of this ring-shaped 2D electron gas can be varied by changing the gate voltage. The magnetoresistance has been measured for T<100 mK and magnetic fields up to 13 Tesla. Aharonov-Bohm oscillations are observed with amplitudes approaching 5% of the total ring resistance, depending on gate voltage, and extending out to B∼1T. The quantum Hall effect is seen at high fields and yields unexpected non-zero plateaux in Rxx for narrow channels.

Original languageEnglish (US)
Pages (from-to)541-544
Number of pages4
JournalSuperlattices and Microstructures
Issue number4-5
StatePublished - 1988
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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