Quantized conductance in an AlAs two-dimensional electron system quantum point contact

O. Gunawan, B. Habib, E. P. De Poortere, M. Shayegan

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60 Scopus citations


We report experimental results on a quantum point contact (QPC) device formed in a wide AlAs quantum well where the two-dimensional electrons occupy two in-plane valleys with elliptical Fermi contours. To probe the closely-spaced, one-dimensional electric subbands, we fabricated a point contact device defined by shallow etching and a top gate that covers the entire device. The conductance versus top gate bias trace shows a series of weak plateaus at integer multiples of 2 e2/h, indicating a broken valley degeneracy in the QPC and implying the potential use of QPC as a simple "valley filter" device. A model is presented to describe the quantized energy levels and the role of the in-plane valleys in the transport. We also observe a well-developed conductance plateau near 0.7×2 e2/h which may reflect the strong electron-electron interaction in the system.

Original languageEnglish (US)
Article number155436
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number15
StatePublished - 2006

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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