Orbital and valley state spectra of a few-electron silicon quantum dot

C. H. Yang, W. H. Lim, N. S. Lai, A. Rossi, A. Morello, A. S. Dzurak

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Abstract

Understanding interactions between orbital and valley quantum states in silicon nanodevices is crucial in assessing the prospects of spin-based qubits. We study the energy spectra of a few-electron silicon metal-oxide-semiconductor quantum dot using dynamic charge sensing and pulsed-voltage spectroscopy. The occupancy of the quantum dot is probed down to the single-electron level using a nearby single-electron transistor as a charge sensor. The energy of the first orbital excited state is found to decrease rapidly as the electron occupancy increases from N=1 to 4. By monitoring the sequential spin filling of the dot we extract a valley splitting of ∼230μeV, irrespective of electron number. This indicates that favorable conditions for qubit operation are in place in the few-electron regime. © 2012 American Physical Society.

Original languageEnglish
Article number115319
Number of pages5
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume86
Issue number11
DOIs
Publication statusPublished - 12 Sep 2012

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Keywords

  • quantum dots
  • semiconductor quantum dots
  • spin blockade

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