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Physical Review B 89 (2014) 054104

Structural and electronic properties of β-FeSi2 nanoparticles: The role of stacking fault domains

by Robert Imlau, András Kovács, Ervin Mehmedovic, Pengxiang Xu, Andrew A Stewart, Christine Leidinger, Rafal E Dunin-Borkowski, Gustav Bihlmayer, Hartmut Wiggers, Reinhard Carius, Ute Kolb and Martina Luysberg


An Iron-disilicide, crystallized in the β phase (β-FeSi2), has received considerable recent attention because of its advantageous thermoelectric and optical properties, which make it interesting for thermoelectric, as well as light-sensitive and light-emitting applications.

Conventional and aberration-corrected transmission electron microscopy (TEM) and ab initio calculations are used to investigate the structural and electronic properties of β-FeSi2 nanoparticles, which are a promising material for photovoltaic applications due to a band gap of <1 eV and a high absorption coefficient. The nanoparticles have average sizes of ∼20 nm, form aggregates, and are prepared by gas-phase synthesis. Amorphous SiOx shells with thicknesses of ∼1.7 nm around β-FeSi2 cores have been identified on individual nanoparticles using electron energy-loss spectroscopy, while stacking fault domains in the nanoparticles have been observed using high-resolution TEM, nanobeam electron diffraction, and automated diffraction tomography. Ab initio calculations indicate only minor changes in band structure in the faulted structure when compared to perfect β-FeSi2. The optical properties of imperfect β-FeSi2 nanoparticles are therefore expected to be the same as those of the perfect structure, suggesting that β-FeSi2 nanoparticles are suitable candidates for use in optical absorber layers in thin film solar cells.


Further reading:

Robert Imlau, András Kovács, Ervin Mehmedovic, Pengxiang Xu, Andrew A Stewart, Christine Leidinger, Rafal E Dunin-Borkowski, Gustav Bihlmayer, Hartmut Wiggers, Reinhard Carius, Ute Kolb and Martina Luysberg
: Structural and electronic properties of β-FeSi2 nanoparticles: The role of stacking fault domains, Physical Review B 89 (2014) 054104.

   
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