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

The elusive X-Defect, a defect found in low-resistivity p -type Silicon after irradiation, observed as a low-temperature shoulder of the B i O 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 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 lack of impact on the effective doping concentration N eff . • X-Defect is the Silicon di-vacancy in the donor state V 2 ( + / 0 ) . • X-Defect does not impact N eff .