High-pressure core structures of Si nanoparticles for solar energy conversion

S. Wippermann, M. Vörös, D. Rocca, A. Gali, G. Zimanyi, G. Galli

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

We present density functional and many body perturbation theory calculations of the electronic, optical, and impact ionization properties of Si nanoparticles (NPs) with core structures based on high-pressure bulk Si phases. Si particles with a BC8 core structure exhibit significantly lower optical gaps and multiple exciton generation (MEG) thresholds, and an order of magnitude higher MEG rate than diamondlike ones of the same size. Several mechanisms are discussed to further reduce the gap, including surface reconstruction and chemistry, excitonic effects, and embedding pressure. Experiments reported the formation of BC8 NPs embedded in amorphous Si and in amorphous regions of femtosecond-laser doped "black silicon." For all these reasons, BC8 nanoparticles may be promising candidates for MEG-based solar energy conversion.

Original languageEnglish
Article number046804
JournalPhysical review letters
Volume110
Issue number4
DOIs
Publication statusPublished - Jan 24 2013

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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