Optical characterization of ultrasmall Si nanoparticles prepared through electrochemical dispersion of bulk Si

Dean A. Eckhoff, Jason D.B. Sutin, Robert M. Clegg, Enrico Gratton, Elena V. Rogozhina, Paul V. Braun

Research output: Contribution to journalArticlepeer-review

Abstract

Studying the properties and stability of silicon nanoparticles (Si-np) in aqueous environments may lead to novel applications in biological systems. In this work, we use absorption and photoluminescence (PL) spectroscopy to characterize ultrasmall Si-np prepared through anodic etching and ultrasonic fractionation of a crystalline Si wafer. Their behavior is studied over time in 2-propanol and during treatments with water, NaOH, HCl, and H 2O 2. The observed population is divided into two types of material: bright species consisting of well-etched Si-np, -1 nm in diameter, and dark species derived from partially etched or aggregated Si structures. The dark material is seen by its scattering in the 2-propanol and water solutions and is largely removed via precipitation with the NaOH or HCl treatment. The bright material includes three distinct species with their respective emissions in the UV-B, UV-A, and hard-blue regions of the spectrum. The hard-blue PL is shown to have a simple pH dependence with a pK a -3, providing an important insight into its chemical origin and signaling for possible application of Si-np as environmental probes. Our results offer some potential for tailoring the PL properties of ultrasmall Si-np through control of their surface chemistry.

Original languageEnglish (US)
Pages (from-to)19786-19797
Number of pages12
JournalJournal of Physical Chemistry B
Volume109
Issue number42
DOIs
StatePublished - Oct 27 2005

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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