Mechanism of $E_{\gamma }^{\prime }$ Defect Generation in Ionizing-irradiated $a$-SiO${}_2$: The Nonradiative Carrier Capture-Structural Relaxation Model

Abstract

The total ionizing dose (TID) effect of semiconductor devices stems from radiation-induced $E_{\gamma }^{\prime }$ defects in the $a$-SiO${}_2$ dielectrics, but the conventional ``hole transport-trapping'' model of defect generation fails to explain recent basic experiments. Here, we propose an essentially new ``nonradiative carrier capture-structural relaxation'' (NCCSR) mechanism that can consistently explain the puzzling temperature/electric-field dependence, based on spin-polarized HSE06 hybrid functional calculations and existing experimental alignment of defect formation energies and charge capture cross-sections of large-sample oxygen vacancies in $a$-SiO${}_2$. It is revealed that, the long-assumed $V_{O\gamma }$ precursors with high formation energy cannot survive in high temperature-grown $a$-SiO${}_2$; whereas the stable $V_{O\delta }$ can capture irradiation-induced holes via strong electron-phonon coupling, generating metastable $E_{\delta }^{\prime }$ that most relax into stable $E_{\gamma }^{\prime }$. A fractional power-law (FPL) dynamic model is derived based on the mechanism and the Kohlrausch-Williams Watts (KWW) decay function. It can uniformly describe nonlinear data over a wide dose and temperature range. This work not only provides a solid cornerstone for prediction and hardening of TID effects of SiO${}_2$-based semiconductor devices, but also offers a general approach for studying ionizing radiation physics in alternative dielectrics with intrinsic electronic metastability and dispersion.

arXiv comment5 pages, 3 figures in the main text; 4 figures, 2 tables in the appendix

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