Combined multifrequency EPR and DFT study of dangling bonds in a-Si: H

Matthias Fehr, A. Schnegg, B. Rech, K. Lips, Oleksandr Astakhov, Friedhelm Finger, G. Pfanner, C. Freysoldt, J. Neugebauer, Robert Bittl, Christian Teutloff

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Multifrequency pulsed electron paramagnetic resonance (EPR) spectroscopy using S-, X-, Q-, and W-band frequencies (3.6, 9.7, 34, and 94 GHz, respectively) was employed to study paramagnetic coordination defects in undoped hydrogenated amorphous silicon (a-Si:H). The improved spectral resolution at high magnetic field reveals a rhombic splitting of the g tensor with the following principal values: g x=2.0079, g y=2.0061, and g z=2.0034, and shows pronounced g strain, i.e., the principal values are widely distributed. The multifrequency approach furthermore yields precise 29Si hyperfine data. Density functional theory (DFT) calculations on 26 computer-generated a-Si:H dangling-bond models yielded g values close to the experimental data but deviating hyperfine interaction values. We show that paramagnetic coordination defects in a-Si:H are more delocalized than computer-generated dangling-bond defects and discuss models to explain this discrepancy.

Original languageEnglish
Article number245203
JournalPhysical Review B
Issue number24
Publication statusPublished - 13 Dec 2011
Externally publishedYes

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