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Conductance of quantum point contacts calculated using realistic potentials

Publication ,  Journal Article
Nixon, JA; Davies, JH; Baranger, HU
Published in: Superlattices and Microstructures
January 1, 1991

The quantized conductance of ballistic electrons in narrow constrictions requires the low scattering rates of a high mobility 2-dimensional electron gas(2DEG). Despite the spectacular mobilities of 2DEGs, quantization breaks down for constrictions longer than about 500 nm, whereas the mean free path in the ungated 2DEG may exceed 10 μm. We show that potential fluctuations from a random distribution of ionised donors modify the guiding potential from the gate in an unpredictable way. The fluctuations are responsible for the variability among nominally identical devices. For a short constriction (200 nm) the conductance can be well quantized. The accuracy of quantization in a longer constriction (600 nm) is reduced by scattering from the random potential of the donors. This occurs when the length scale of the constriction is greater than that of the fluctuations. The conductance characteristics depend strongly on the exact configuration of impurities. In some cases the random potential causes a resonance in the channel. © 1991.

Duke Scholars

Published In

Superlattices and Microstructures

DOI

EISSN

1096-3677

ISSN

0749-6036

Publication Date

January 1, 1991

Volume

9

Issue

2

Start / End Page

187 / 190

Related Subject Headings

  • Applied Physics
  • 5104 Condensed matter physics
  • 5102 Atomic, molecular and optical physics
  • 4009 Electronics, sensors and digital hardware
  • 0206 Quantum Physics
  • 0205 Optical Physics
  • 0204 Condensed Matter Physics
 

Citation

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Nixon, J. A., Davies, J. H., & Baranger, H. U. (1991). Conductance of quantum point contacts calculated using realistic potentials. Superlattices and Microstructures, 9(2), 187–190. https://doi.org/10.1016/0749-6036(91)90280-5
Nixon, J. A., J. H. Davies, and H. U. Baranger. “Conductance of quantum point contacts calculated using realistic potentials.” Superlattices and Microstructures 9, no. 2 (January 1, 1991): 187–90. https://doi.org/10.1016/0749-6036(91)90280-5.
Nixon JA, Davies JH, Baranger HU. Conductance of quantum point contacts calculated using realistic potentials. Superlattices and Microstructures. 1991 Jan 1;9(2):187–90.
Nixon, J. A., et al. “Conductance of quantum point contacts calculated using realistic potentials.” Superlattices and Microstructures, vol. 9, no. 2, Jan. 1991, pp. 187–90. Scopus, doi:10.1016/0749-6036(91)90280-5.
Nixon JA, Davies JH, Baranger HU. Conductance of quantum point contacts calculated using realistic potentials. Superlattices and Microstructures. 1991 Jan 1;9(2):187–190.
Journal cover image

Published In

Superlattices and Microstructures

DOI

EISSN

1096-3677

ISSN

0749-6036

Publication Date

January 1, 1991

Volume

9

Issue

2

Start / End Page

187 / 190

Related Subject Headings

  • Applied Physics
  • 5104 Condensed matter physics
  • 5102 Atomic, molecular and optical physics
  • 4009 Electronics, sensors and digital hardware
  • 0206 Quantum Physics
  • 0205 Optical Physics
  • 0204 Condensed Matter Physics