Quantum confinement, surface roughness, and the conduction band structure of ultrathin silicon membranes

Feng Chen, Edwin B. Ramayya, Chanan Euaruksakul, Franz J. Himpsel, George K. Celler, Bingjun Ding, Irena Knezevic, Max G. Lagally

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

We report direct measurements of changes in the conduction-band structure of ultrathin silicon nanomembranes with quantum confinement. Confinement lifts the 6-fold-degeneracy of the bulk-silicon conduction-band minimum (CBM), Δ, and two inequivalent sub-band ladders, Δ2 and Δ4, form. We show that even very small surface roughness smears the nominally steplike features in the density of states (DOS) due to these sub-bands. We obtain the energy splitting between Δ2 and Δ4 and their shift with respect to the bulk value directly from the 2p3/2→Δ transition in X-ray absorption. The measured dependence of the sub-band splitting and the shift of their weighted average on degree of confinement is in excellent agreement with theory, for both Si(001) and Si(110).

Original languageEnglish (US)
Pages (from-to)2466-2474
Number of pages9
JournalACS Nano
Volume4
Issue number4
DOIs
Publication statusPublished - Apr 27 2010
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Keywords

  • Quantum confinement
  • Silicon nanomembrane
  • Surface roughness
  • Thermoelectric
  • Valley splitting

Cite this

Chen, F., Ramayya, E. B., Euaruksakul, C., Himpsel, F. J., Celler, G. K., Ding, B., ... Lagally, M. G. (2010). Quantum confinement, surface roughness, and the conduction band structure of ultrathin silicon membranes. ACS Nano, 4(4), 2466-2474. https://doi.org/10.1021/nn100275z