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arXiv · 2508.16197

On the nature and charge state of the X-Defect, a radiation-induced Silicon defect with field-enhanced charge carrier emission

Niels Sorgenfrei·Yana Gurimskaya·Anja Himmerlich·Michael Moll·Ulrich Parzefall·Ioana Pintilie·Joern Schwandt
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Abstract

The elusive X-Defect, a defect found in low-resistivity $p$-type Silicon after irradiation, observed as a low-temperature shoulder of the $\mathrm{B}_\mathrm{i}\mathrm{O}_\mathrm{i}$ defect (Boron-interstitial-Oxygen-interstitial complex) in Thermally Stimulated Current (TSC) measurements, was investigated to determine its properties, matching them with those of a previously identified defect. Through a combination of TSC, Deep-Level Transient Spectroscopy (DLTS), Difference-DLTS (DDLTS), numerical simulations of field-enhanced charge carrier emissions in TSC measurements and a comparison to literature, the X-Defect was identified as the singly positively charged Silicon di-vacancy $\mathrm{V}_2(+/0)$. This assignment is supported by an agreement in activation energy, capture cross-section, trap type and charge emission process, as well as simulations comparing the effects of phonon-assisted tunnelling (PAT) and Poole-Frenkel (PF) mechanisms on TSC spectra. DDTLS measurements revealed a quadratic dependence of the activation energy on the electric field strength, confirming PAT as the prevailing mechanism over PF in the case of the radiation-induced X-Defect. Assigning the X-Defect to an electrically neutral defect in the space charge region resolves previous contradictions regarding its deficiency in impacting on the effective doping concentration.

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Niels Sorgenfrei, Yana Gurimskaya, Anja Himmerlich, Michael Moll, Ulrich Parzefall, Ioana Pintilie, Joern Schwandt. 2025-08-22. On the nature and charge state of the X-Defect, a radiation-induced Silicon defect with field-enhanced charge carrier emission. https://doi.org/10.1016/j.nima.2025.171133

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