2014
DOI: 10.1103/physrevb.89.125201
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Nature of intrinsic and extrinsic electron trapping in SiO2

Abstract: Using ab initio calculations we demonstrate that extra electrons in pure amorphous SiO2 can be trapped in deep band gap states. Classical potentials were used to generate amorphous silica models and density functional theory to characterize the geometrical and electronic structures of trapped electrons. Extra electrons can trap spontaneously on pre-existing structural precursors in amorphous SiO2 and produce ≈ 3.2 eV deep states in the band gap. These precursors comprise wide (≥132 • ) O-Si-O angles and elonga… Show more

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Cited by 111 publications
(112 citation statements)
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“…The distributions of Si-O bonds and Si-O-Si angles in our samples are described in detail in Ref. [36] and agree well with previous calculations by other authors [41]. We have calculated the neutron structure factors for our models and they show excellent agreement with experiment [42], indicating that our models describe both the short-and long-range order and are indeed representative of a-SiO 2 .…”
supporting
confidence: 78%
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“…The distributions of Si-O bonds and Si-O-Si angles in our samples are described in detail in Ref. [36] and agree well with previous calculations by other authors [41]. We have calculated the neutron structure factors for our models and they show excellent agreement with experiment [42], indicating that our models describe both the short-and long-range order and are indeed representative of a-SiO 2 .…”
supporting
confidence: 78%
“…This center is thought to result from the interaction of H 0 with electronically excited strained Si-O bonds [30]. Strained Si-O bonds in amorphous silica, that is those bonds whose length deviates strongly from the crystalline equilibrium value of 1.61Å, have been the focus of many other studies due to their relatively high reactivity [30,[32][33][34][35][36]. However, reactions of atomic hydrogen with strained Si-O bonds have not been investigated theoretically, except in [32], and the perception that atomic hydrogen interacts only weakly with the silica network still prevails in the literature [1, 7,37].…”
mentioning
confidence: 99%
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“…The ReaxFF force-field 43,44 and a classical MD melt and quench procedure are used with the LAMMPS code 45 to generate starting structures representing non-defective continuous random networks of a-SiO 2 . 46 These structures containing 216 atoms each were evaluated 46 by comparing the distributions of Si-O bonds, Si-O-Si angles, and neutron structure factors to prior theoretical and experimental studies before being used for DFT calculations. DFT calculations of the electronic and geometric structures and nudged elastic band calculations 47,48 of adiabatic barriers were performed using the Gaussians and Plane Waves method 49 implemented in the CP2K code.…”
Section: B Atomistic Simulationsmentioning
confidence: 99%
“…Clustering of vacancies 35 or their interaction with hydrogen, as recently revealed in the case of a-SiO 2 , 36 represent feasible models deserving further theoretical and experimental analysis. Second, self-trapping of electrons on oxide network sites under strained bonding geometries may also provide deep acceptor states in the amorphous phases 37 or inside the grain boundary region in polycrystalline HfO 2 . Considerable site-to-site variations in the trapping geometry expected in this case may explain the relatively wide energy distributions of the trapped electrons as well as the mentioned failure of ESR to detect the corresponding paramagnetic state because of excessive line broadening.…”
mentioning
confidence: 99%