Oxygen defects in amorphous Al2O3

Authors: Zhendong Guo1*, Francesco Ambrosio1, Alfredo Pasquarello1*

  1. Chaire de Simulation à l’Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
  • Corresponding authors emails: zhendong.guo@epfl.ch, alfredo.pasquarello@epfl.ch

DOI10.24435/materialscloud:2019.0026/v1 (version v1, submitted on 30 May 2019)

How to cite this entry

Zhendong Guo, Francesco Ambrosio, Alfredo Pasquarello, Oxygen defects in amorphous Al2O3, Materials Cloud Archive (2019), doi: 10.24435/materialscloud:2019.0026/v1.

Description

The electronic properties of the oxygen vacancy and interstitial in amorphous Al2O3 are studied via ab initio molecular dynamics simulations and hybrid functional calculations. Our results indicate that these defects do not occur in amorphous Al2O3, due to structural rearrangements which assimilate the defect structure and cause a delocalization of the associated defect levels. The imbalance of oxygen leads to a nonstoichiometric compound in which the oxygen occurs in the form of O2– ions. Intrinsic oxygen defects are found to be unable to trap excess electrons. For low Fermi energies, the formation of peroxy linkages is found to be favored leading to the capture of holes. The relative +2/0 defect levels occur at 2.5 eV from the valence band.

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Files

File name Size Description
O-O_2hole.xyz
MD5MD5: ba093a0d312f7b34b679d4b03c1701ab
10.2 KiB The relaxed atomic structure of the O-O peroxy linkage induced by the addition of two holes into the bulk model.
Oi_-2.xyz
MD5MD5: a060cd082cfb999cafdc4ecff725490d
10.2 KiB The atomic structure of a defect-free substoichiometric oxide obtained after carrying out MD simulations for the bulk model with the addition of an O2- ion.
am-Al2O3_VO_2.xyz
MD5MD5: 6e358e93507a3ab00bb03ea0ceac67a7
10.1 KiB The atomic structure of a defect-free substoichiometric oxide achieved after performing an annealing cycle using MD simulations for the bulk model with an O2- ion removed.
am-Al2O3_bulk_model.xyz
MD5MD5: 82a85d37defb4f66a3afc8e0fdc33d43
10.4 KiB The atomic structure of the bulk amorphous Al2O3 model constructed through the melt-and-quench method [D. Colleoni, G. Miceli, and A. Pasquarello, Appl. Phys. Lett. 107, 211601 (2015)]. This model contains 160 atoms, with the lattice parameters of 11.47, 11.24, and 12.78 angstrom in the x, y and z direction, respectively.
Oi_0_type1.xyz
MD5MD5: 23496d60188585deb455eb727c649ac3
10.2 KiB The relaxed atomic structure of an O-O peroxy linkage formed upon the insertion of a neutral interstitial oxygen atom. In this configuration, the two O atoms in the peroxy linkage are bonded to different Al atoms.
Oi_0_type2.xyz
MD5MD5: 97f00f601b53ab23f394a380e95da02a
10.2 KiB The relaxed atomic structure of an O-O peroxy linkage formed upon the insertion of a neutral interstitial oxygen atom. In this configuration, the two O atoms in the peroxy linkage form one bond to the same Al atom.
README.txt
MD5MD5: d0e1200515f0b949abd0d83c4d2fe242
1.3 KiB Description of the file contents.

License

Files and data are licensed under the terms of the following license: Creative Commons Attribution 4.0 International.

External references

Journal reference
Z. Guo, F. Ambrosio, A. Pasquarello, Applied Physics Letters 109, 062903 (2016) doi:10.1063/1.4961125

Keywords

amorphous Al2O3 oxygen vacancy oxygen interstitial peroxy linkage holes

Version history

30 May 2019 [This version]