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arXiv · 2610.06173

State aligned graph wavelet fingerprints of electron trapping in amorphous Si$_3$N$_4$

Jonathon Cottom·Emilia Olsson
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Abstract

Classifying charge traps in amorphous materials requires the electronic state and the network response to be resolved together. We develop state-aligned graph-wavelet fingerprints and apply them to electron trapping in a-Si$_3$N$_4$, where intrinsic-polaronic trapping, coordination-driven trapping, and charge-driven conversion coexist within one ensemble. Across 415 pairs of relaxed neutral and negatively charged cells, alignment of the trap state before and after localisation connects electronic identity to multiscale structural fingerprints. Charge-driven conversion produces substantial reorganisation across graph scales and increases the fingerprint amplitude. The fingerprint change identifies the transformation each site undergoes, while the occupation-induced level shift tracks localisation gain and graph deformation tracks stabilisation. Charge-induced defect formation dominates the deepest spectral-trap decile: 69\% form at sites whose Si--N bond breaks on capture, although this route accounts for 44.2\% of the classified traps. The fingerprints unify electronic identity, multiscale network reorganisation and energetic stabilisation in a quantitative framework for resolving charge trapping in amorphous materials.

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Jonathon Cottom, Emilia Olsson. 2026-10-05. State aligned graph wavelet fingerprints of electron trapping in amorphous Si$_3$N$_4$. https://arxiv.org/abs/2610.06173

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