Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors

Lany, Stephan; Zunger, Alex

doi:10.1103/physrevb.80.085202

Cited by 375 publications

(409 citation statements)

References 37 publications

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“…Further addition of a second extra electron does not cause significant distortion of the system but only a tiny distortion of the bottom of CB in a commonly described perturbed host state (PHS) [32], where the electron is delocalized. The corresponding (0=À1) and (À1=À2) transition energy levels computed with the present computational setup (0.91 and 0.12 eV below the CB bottom, respectively) are consistent with the experimental data and a recent GGA þ U study [18]. While Cu s 2þ is a good acceptor that can easily capture electrons from any shallow donors present in the bulk [(0=À1) charge transition], Cu s þ is a very poor acceptor [(À1=À2) charge transition].…”

Section: Prl 106 066401 (2011) P H Y S I C a L R E V I E W L E T T Esupporting

confidence: 75%

“…The unpaired electron is highly localized on a Cu d z 2 -orbital. The Cu s 2þ species has been previously studied and identified as a deep acceptor [18,30,31]. The addition of an extra electron fills up the Cu 3d shell (Cu s þ ) and induces a considerable outward relaxation of the nearest O atoms (E rel ¼ 0:58 eV), restoring the original zinc tetrahedral coordination.…”

Section: Prl 106 066401 (2011) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

“…Several studies based on photoluminescence experiments [14,15], electrical measurements [16,17], and on GGA þ U calculations [18] have reported a deep acceptor state with the transition energy level (0, À1) high in the band gap. In this Letter we present a combined experimental and theoretical study of the Cu=ZnO system prepared by Cu deposition on ZnO single crystal surfaces.…”

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confidence: 99%

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Shallow Donor States Induced by In-Diffused Cu in ZnO: A Combined HREELS and Hybrid DFT Study

et al. 2011

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A combined experimental and first principles study of Cu defects in bulk ZnO is presented. Cu particles are epitaxially deposited on the polar O-ZnOð000 " 1Þ surface at room temperature. Upon heating, a broadening of the quasielastic peak in high resolution electron energy loss spectra is observed, corresponding to an electronic doping effect of Cu atoms in bulk ZnO with an ionization energy of 88 meV. Cu impurities in ZnO, although commonly acting as acceptors, are presently observed to induce shallow donor states. We assign these to interstitial Cu species on the basis of a hybrid density functional study.

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Section: Prl 106 066401 (2011) P H Y S I C a L R E V I E W L E T T Esupporting

confidence: 75%

Section: Prl 106 066401 (2011) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

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confidence: 99%

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Shallow Donor States Induced by In-Diffused Cu in ZnO: A Combined HREELS and Hybrid DFT Study

et al. 2011

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“…31 The U value for the oxygen atoms was derived using an ab initio fitting procedure with a Koopman'slike approach. 32,51 This additional term is only applied to bulk CeO 2 calculations and not the clusters. As with the Ti clusters, all Ce-based clusters were simulated in 25 Å Â 25 Å Â 25 Å boxes with a single k-point at G and the structures were held fixed to ensure orbital degeneracies would not be affected by structural variations.…”

Section: Methodsmentioning

confidence: 99%

Occupation matrix control of d- and f-electron localisations using DFT + U

Allen

Watson

2014

Phys. Chem. Chem. Phys.

192

200

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The use of a density functional theory methodology with on-site corrections (DFT + U) has been repeatedly shown to give an improved description of localised d and f states over those predicted with a standard DFT approach. However, the localisation of electrons also carries with it the problem of metastability, due to the possible occupation of different orbitals and different locations. This study details the use of an occupation matrix control methodology for simulating localised d and f states with a plane-wave DFT + U approach which allows the user to control both the site and orbital localisation.This approach is tested for orbital occupation using octahedral and tetrahedral Ti(III) and Ce(III) carbonyl clusters and for orbital and site location using the periodic systems anatase-TiO 2 and CeO 2 . The periodic cells are tested by the addition of an electron and through the formation of a neutral oxygen vacancy (leaving two electrons to localise). These test systems allow the successful study of orbital degeneracies, the presence of metastable states and the importance of controlling the site of localisation within the cell, and it highlights the use an occupation matrix control methodology can have in electronic structure calculations.

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“…Density functional theory 3,4 (DFT) remains the most widely used method for this purpose. In spite of recent advances such as the use of hybrid DFT 5 , GW 6 , and a generalized Koopman's method 7 , questions to the quantitative accuracy attainable still remain, and often similar defect calculations can result in different predictions. The challenges broadly arise from two sources: errors inherent to DFT's approximate treatment of electron-electron interactions, and finite size effects from practical limitations to the computational domain.…”

Section: Introductionmentioning

confidence: 99%

Fixed-node diffusion Monte Carlo description of nitrogen defects in zinc oxide

Wagner

Ertekin

2017

Phys. Rev. B

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Using fixed-node diffusion Monte Carlo (FN-DMC), we evaluate the formation energies and charge transition levels of substitutional nitrogen defects in the wide band gap semiconductor zinc oxide. The use of a direct-solution, many-body approach inherently secures a good description of electronelectron interactions, achieving high accuracy without adjustable parameters. According to FN-DMC nitrogen is a deep acceptor with a charge transition level 1.0(3) eV above the valence band maximum when 72 atom supercells are used. This result falls on the lower end of typically reported hybrid density functional results for the same sized supercells, which range from 1.0 -1.8 eV. Further, residual finite size effects due to charged defect image interactions in the 72 atom supercells are estimated by supercell extrapolation within hybrid density functional theory. When the finite size correction is included, we obtain a deep acceptor at 1.6(3) eV. This result is in good agreement with recent experimental measurements. We also analyze the local compressibility of charge according to FN-DMC and common density functionals, and find that the use of hybrid functionals obtain compressibilities in better agreement with the many-body theory. Our work illustrates the application of the FN-DMC method to a challenging point defect problem, demonstrating that uncertainties and approximations can be well-controlled.

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Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors

Cited by 375 publications

References 37 publications

Shallow Donor States Induced by In-Diffused Cu in ZnO: A Combined HREELS and Hybrid DFT Study

Shallow Donor States Induced by In-Diffused Cu in ZnO: A Combined HREELS and Hybrid DFT Study

Occupation matrix control of d- and f-electron localisations using DFT + U

Fixed-node diffusion Monte Carlo description of nitrogen defects in zinc oxide

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