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arXiv · 1103.5641

Dangling bonds in a-Si:H revisited: A combined Multifrequency EPR and DFT Study

M. Fehr·A. Schnegg·B. Rech·K. Lips·O. Asthakov·F. Finger·G. Pfanner·C. Freysoldt·J. Neugebauer·R. Bittl·C. Teutloff
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Abstract

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 ^{29}Si 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.

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M. Fehr, A. Schnegg, B. Rech, K. Lips, O. Asthakov, F. Finger, G. Pfanner, C. Freysoldt, J. Neugebauer, R. Bittl, C. Teutloff. 2011-03-29. Dangling bonds in a-Si:H revisited: A combined Multifrequency EPR and DFT Study. https://arxiv.org/abs/1103.5641

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