Investigations of the non-linear transient response of quantum point contacts using pulsed excitation with sub-nanosecond time resolution

B. Naser, D. K. Ferry, J. Heeren, J. L. Reno, J. P. Bird

Research output: Contribution to journalArticlepeer-review

Abstract

We review recent work where we have investigated the non-linear transient response of quantum point contacts (QPCs) using pulsed excitation with sub-nanosecond time resolution. The transient response of these devices is shown to be dominated by a large parallel capacitance that is independent of the QPC conductance and pulse amplitude. These characteristics lead us to suggest that the capacitance is associated with charging of the two-dimensional reservoirs that source and sink current to the QPC. Our investigations also show that the transient conductance of the QPC must develop very quickly as the voltage pulse is applied, at least on a time scale shorter than the fastest rise time (2 ns) used in the experiments. We also find the existence of a characteristic fixed point in the non-linear conductance, at which its value is bias independent. The fixed point appears to correspond to the situation where the unbiased QPC is almost depopulated and can be accounted for by considering the unidirectional population of QPC subbands by the voltage bias. To discuss the behavior of the transient conductance away from the fixed point, we find that it should be necessary to consider the influence of the applied bias on the QPC profile and electron-phonon scattering.

Original languageEnglish (US)
Pages (from-to)84-91
Number of pages8
JournalPhysica E: Low-Dimensional Systems and Nanostructures
Volume40
Issue number1
DOIs
StatePublished - Oct 1 2007

Keywords

  • Non-linear transport
  • Quantum point contact
  • Transient conductance

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics

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