First principle study of neutral and charged self-defects in amorphous SiO2

Richard, Nicolas; Martin‐Samos, Layla; Roma, Guido; Limoge, Yves; Crocombette, Jean-Paul

doi:10.1016/j.jnoncrysol.2005.04.024

Cited by 36 publications

(36 citation statements)

References 16 publications

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“…The only difference between initial and annealed models is in dislocated oxygen atoms and in the bonding layout in the interface region. (figure 3) In all interfaces, after simulation of thermal treatment, the reconstruction of the interfaces generates defects in form of three-coordinated [Si(3)] silicon atoms, (dangling bond) [20][21][22][34][35][36][37] five coordinated silicon atoms (floating bond) [38][39][40] , threefold-coordinated oxygen atom 41,42 or displaced oxygen atom 42 .…”

Section: Resultsmentioning

confidence: 99%

Structure, defects, and strain in silicon-silicon oxide interfaces

Kovačević¹,

Pivac²

2014

Journal of Applied Physics

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ABSTRACT:The structure of the interfaces between silicon and silicon-oxide are responsible for proper functioning of MOSFET devices while defects in the interface can deteriorate this function and lead to theirs failure. In this paper we modeled this interface and characterized its defects and strain. MD simulations were used for reconstructing interfaces into a thermodynamically stable configuration. In all modeled interfaces, defects were found in form of three-coordinated silicon atom, five coordinated silicon atom, threefold-coordinated oxygen atom or displaced oxygen atom. Three-coordinated oxygen atom can be 2 created if dangling bonds on silicon are close enough. The structure and stability of three-coordinated silicon atoms (Pb defect) depend on the charge as well as on the electric field across the interface. The negatively charged Pb defect is the most stable one, but the electric field resulting from the interface reduces that stability. Interfaces with large differences in periodic constants of silicon and silicon oxide can be stabilized by buckling of silicon layer. Mechanical stress resulted from the interface between silicon and silicon oxide is greater in the silicon oxide layer. Ab-initio modeling of clusters representing silicon and silicon oxide shows about three time larger susceptibility to strain in silicon oxide than in silicon if exposed to the same deformation.

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Section: Resultsmentioning

confidence: 99%

Structure, defects, and strain in silicon-silicon oxide interfaces

Kovačević¹,

Pivac²

2014

Journal of Applied Physics

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“…The formation energy difference between the neutral dimer (NOV) and the E 1 in bulk α-quartz is about −0.35 eV. 63 The E γ is lower in energy than the NOV in silica, but only by about 0.30 eV 64 when E F =E VBM . Thus, we can expect that E γ defects are more likely to be found in higher concentrations on the surface than in the bulk, since they are 2 eV more stable.…”

Section: +mentioning

confidence: 99%

“…Our calculations of the formation energies of the charged and neutral ODCs are in agreement with previous calculations, showing that the neutral ODC is thermodynamically more stable. 16,17,20 However, some calculations of the formation energy of E defects set the Fermi Energy 2.25-3.3eV above the VBM 63,64 (much closer to the VBM than to the center of the gap). On the (100) surface, if the Fermi energy is taken to be ∼2 eV above the VBM or lower, the 1+ PC configuration is more stable than the NOV.…”

Section: +mentioning

confidence: 99%

Magnetic stability of oxygen defects on the SiO2 surface

et al. 2017

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The magnetic stability of E′ centers and the peroxy radical on the surface of α-quartz is investigated with first-principles calculations to understand their role in magnetic flux noise in superconducting qubits (SQs) and superconducting quantum interference devices (SQUIDs) fabricated on amorphous silica substrates. Paramagnetic E′ centers are common in both stoichiometric and oxygen deficient silica and quartz, and we calculate that they are more common on the surface than the bulk. However, we find the surface defects are magnetically stable in their paramagnetic ground state and thus will not contribute to 1/f noise through fluctuation at millikelvin temperatures.

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“…The seven puckered configurations of the 5× group differ from the 4 × group by the presence of a two-membered ring with a threefold oxygen atom. 30 Three of them are back-projected puckered 5× configurations and four of them are forward-projected puckered 5 × configurations. Actually, one configuration is a special forward-projected puckered 5× configuration with the d Si-Si of 2.82 Å, which is also in the range of Si 2 dimer configurations.…”

Section: Resultsmentioning

confidence: 99%

“…27 Take a self-consistent way in previous reports, we choose µ e − = 2.25 eV in our research. [28][29][30] The lack of long-range ordering hinders the use of computational modeling for a-SiO 2 . However, recent published works have opened a way to the use of periodic-DFT methods as implemented in VASP (Vienna ab initio simulation package) for modeling amorphous surfaces.…”

Section: Introductionmentioning

confidence: 99%

First principles study of oxygen vacancy defects in amorphous SiO2

2017

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The oxygen vacancy defects of amorphous SiO2 (a-SiO2) in different charge states are investigated by the periodic density functional theory. Five types of the positively charged configurations are obtained including the dimer, forward-oriented, puckered 4×, 5× and back-projected unpuckered configurations. The energy, geometry structure, spin density, Bader charge and Fermi contact are concerned for these systems. These defects can be regarded as the potential microscopic structures for the corresponding centers including Eα′, Eγ′ and Eδ′ in the electron paramagnetic resonance (EPR) experiments. Then, the charge-state transitions of these defects are investigated by intentionally adding one electron to the positively charged systems. For the dimer, puckered 4× and back-projected unpuckered configurations, all of the corresponding neutral species maintain their initial types of geometry structures. For the forward-oriented configurations, the corresponding neutral species transform into the structures of the divalent Si atom. The puckered 5× configurations have the most abundant neutral species: some of them could maintain its style of the puckered 5× configurations, and some collapse to the neutral dimer or forward-oriented configurations. The dimer configurations have the lowest thermodynamic charge-state levels, and the puckered 4× configurations have the highest thermodynamic charge-state levels among the five types of configurations. This work is of benefit to identifying and controlling the oxygen defects in a-SiO2.

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First principle study of neutral and charged self-defects in amorphous SiO2

Cited by 36 publications

References 16 publications

Structure, defects, and strain in silicon-silicon oxide interfaces

Structure, defects, and strain in silicon-silicon oxide interfaces

Magnetic stability of oxygen defects on the SiO2 surface

First principles study of oxygen vacancy defects in amorphous SiO2

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