On the origin of photoluminescence in silicon nanocrystals: Pressure-dependent structural and optical studies

Daniel C. Hannah, Jihua Yang, Paul Podsiadlo, Maria K Y Chan, Arnaud Demortière, David J. Gosztola, Vitali B. Prakapenka, George C. Schatz, Uwe Kortshagen, Richard D. Schaller

Research output: Contribution to journalArticlepeer-review

98 Scopus citations

Abstract

A lack of consensus persists regarding the origin of photoluminescence in silicon nanocrystals. Here we report pressure-dependences of X-ray diffraction and photoluminescence from alkane-terminated colloidal particles. We determine the diamond-phase bulk modulus, observe multiple phase transitions, and importantly find a systematic photoluminescence red shift that matches the X conduction-to-Λ valence transition of bulk crystalline silicon. These results, reinforced by calculations, suggest that the efficient photoluminescence, frequently attributed to defects, arises instead from core-states that remain highly indirect despite quantum confinement.

Original languageEnglish (US)
Pages (from-to)4200-4205
Number of pages6
JournalNano letters
Volume12
Issue number8
DOIs
StatePublished - Aug 8 2012

Keywords

  • Quantum dot
  • X-ray diffraction
  • diamond anvil cell
  • nanocrystal
  • photoluminescence
  • pressure
  • silicon

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