Electron−Phonon Coupling and Localization of Excitons in Single Silicon Nanocrystals

• Published in: Nano letters 2008-02, Vol.8 (2), p.656-660
• Main Authors: Martin, Jörg, Cichos, Frank, Huisken, Friedrich, von Borczyskowski, Christian
• Format: Article
• Language: English
• Subjects: Computer Simulation; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Electric Conductivity; Electron states; Electron Transport; Electrons; Exact sciences and technology; Excitons and related phenomena; Laser-assisted deposition; Light; Materials science; Materials Testing; Methods of nanofabrication; Models, Chemical; Nanocrystalline materials; Nanocrystals and nanoparticles; Nanoscale materials and structures: fabrication and characterization; Nanostructures - chemistry; Nanotechnology - methods; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Particle Size; Photons; Physics; Radiation Dosage; Silicon - chemistry
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl0731163

We report a detailed photoluminescence (PL) study on single silicon nanocrystals produced by laser pyrolysis. The PL spectra reveal nearly homogeneously broadened zero-phonon lines coupled to Si−O−Si phonon transitions in the SiO2 shell. A systematic investigation of electron−phonon coupling is reported on the basis of single nanocrystals. The stepwise localization of electron and hole at the Si−SiO2 interface for nanocrystals smaller than d ≈ 2.7 nm is driven by electron−phonon coupling. From the localization energies the effective Bohr radii of the (localized) electron and hole are estimated to be in the range of 1−2 bond lengths of Si−O and Si−Si.