Radiation-induced E″ centers in crystalline SiO2

E′Centers inαQuartz in the Absence of Oxygen Vacancies: A First-Principles Molecular-Dynamics Study

“…This has a small effect on the average SiOSi angles of the ring that read 1 120:0 , 2 139:1 , and 3 133:4 . This spin distribution is adopted by the system in an attempt at minimizing the electrostatic repulsion between the two spin-up electrons; in fact, the distances of Si(1) from the O atoms composing the three-membered ring range from 4.74 to 7:98 A, which is in accord with the experimental estimate of the two parallel spins in the triplet state [23]. The Hf parameters for this state are remarkably close to the experimental values for an E 0 1 center (Table II).…”

“…Thus, alternative models have been proposed, involving the trapping of a hole at a triangular ODC [20] or at different types of puckered configurations [21]. The microscopic identification of E 0 has become even more complicated in that radiation-induced E 0 -like centers in quartz were identified as triplet states [22,23]. This seems to be consistent with the one-photon UV irradiation experiments [24].…”

Origins of optical absorption between 4.8 and 4.9eV in silica implanted with Si and with O ions

“…The center could only be observed in the samples implanted with the larger oxygen concentrations (P0.35 at.%), from where we suggest that the center is oxygen excess related. Since S = 1 states have been previously observed in crystalline quartz [26,27] and in silica [28,32] an intensive effort was made to detect the Dm = 2 transitions of S = 1 centers, possibly occurring at half the field of the Dm = 1 transitions. However, none were detected.…”

E' Centers in Silicon Dioxide: First-Principles Molecular Dynamics Studies

“…[68][69][70] Furthermore, more recently, both laser pulsed 5 and UV light 6 have been shown to be able to promote the formation of this kind of defects. It has then become clear that electron excitations are involved, at least in some cases.…”