Structural and electronic properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>3</mml:mn><mml:mi>d</mml:mi></mml:math>transition metal impurities in silicon carbide

Assali, L. V. C.; Machado, W.V.M.; Justo, J. F.

doi:10.1103/physrevb.69.155212

Cited by 55 publications

(34 citation statements)

References 30 publications

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“…Self-consistent interactions were performed until convergence on the total energy and the atomic forces of respectively 10 −4 eV and 0.02 eV/Å were achieved. This methodology has been successfully applied to a number of defects in semiconductors [6][7][8].…”

Section: Methodsmentioning

confidence: 99%

Microscopic structure of nickel-dopant centers in diamond

et al. 2006

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We present a theoretical investigation on the properties of interstitial nickel and its related complexes in diamond. The atomic configurations, symmetries, spins, and energetics of interstitial nickel, nickel-boron and nickel-vacancy complexes were investigated by a total energy ab initio methodology. Those results are used to explain certain electrically active centers, commonly found in synthetic diamond.

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Section: Methodsmentioning

confidence: 99%

Microscopic structure of nickel-dopant centers in diamond

et al. 2006

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“…Such theoretical framework and convergence criteria have been shown to provide a reliable description of the electronic properties of defect centers in several semiconductors 21,22 .…”

Section: Methodsmentioning

confidence: 99%

3dtransition metal impurities in diamond: Electronic properties and chemical trends

2011

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First principles calculations have been used to investigate the trends on the properties of isolated 3d transition metal impurities (from Sc to Cu) in diamond. Those impurities have small formation energies in the substitutional or double semi-vacancy sites, and large energies in the interstitial one.Going from Sc to Cu, the 3d-related energy levels in the bandgap move from the top of the bandgap toward the valence band in all three sites. Trends in electronic properties and transition energies of the impurities, in the substitutional or interstitial sites, are well described by a simple microscopic model considering the electronic occupation of the 3d-related levels. On the other hand, for the impurities in the double semi-vacancy site, there is a weak interaction between the divacancy-and the 3d-related orbitals, resulting in in vacancy-and 3d-related levels in the materials bandgap.

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“…We considered a 56-atom reference hexagonal supercell of GaN or ZnO, with the RE atom in a substitutional cation site. A detailed description of the simulation cell is presented elsewhere [17]. In order to check the convergence of our results with respect to the supercell size, we performed test simulations with larger supercells (up to 108 atoms) and observed that the results were essentially unchanged in comparison to those with the 56-atom supercell.…”

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“…is the smallest atomic sphere radius. All those approximations provide a reliable description on the electronic and structural properties of several impurity centers in semiconductors [17][18][19][20].We initially used an on-site Hubbard potential correction, computed self-consistently [8], for the 3d states of the cation atoms (Ga or Zn, respectively in GaN or ZnO) in the crystal hosts. We found self-consistent values of U 3d (Ga) = 10.9 eV and U 3d (Zn) = 7.6 eV.…”

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Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices

Caroena

Machado

Justo

et al. 2013

Applied Physics Letters

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The electronic properties of lanthanide (from Eu to Tm) impurities in wurtzite gallium nitride and zinc oxide were investigated by first principles calculations, using an all electron methodology plus a Hubbard potential correction. The results indicated that the 4f-related energy levels remain outside the bandgap in both materials, in good agreement with a recent phenomenological model, based on experimental data. Additionally, zinc oxide doped with lanthanide impurities became an n-type material, showing a coupling between the 4f-related spin polarized states and the carriers.This coupling may generate spin polarized currents, which could lead to applications in spintronic devices. [2,3] devices. Rare earth lanthanide atoms exhibit partially filled 4f shells, and intra-4f electric dipole transitions are forbidden for the free ions. On the other hand, the respective transition probabilities increase considerably when the ions are placed in a crystal field, that splits the 4f-related energy levels, modifying the dipole selection rules and leading to luminescent centers [4].Although theoretical modeling has been used to investigate the properties of RE-related materials [5,6], several methodological challenges have hindered an appropriate description of the 4f-related states in crystalline environments, such as RE impurities in semiconductors.It is well documented that the density functional theory generally fails in describing highly correlated systems, such as the interactions in 4f-related electronic states. Such limitations could in part be overcome with the introduction of an on-site Hubbard U potential correction [7][8][9]. One of the major outcomes of this correction is a better description of the energy splitting between occupied and unoccupied 4f-related electronic levels. We have recently shown that this procedure provides a good description of the electronic structure of metallic RE crystals [10], when compared to available experimental data [11]. Here, we show that the same procedure is also appropriate to describe the trends on the 4f-related energy levels of RE impurities (from Eu to Tm), with respect to the bandgap, in wurtzite gallium nitride and zinc oxide crystals. The results were discussed in the context of a recent phenomenological model to determine the energy positions of 4f-related electronic systems in crystalline environments [12]. Our results also indicate that doping ZnO with lanthanide impurities leads to a ntype material, with a magnetic coupling between the 4f-related states and the carriers.This suggests that such systems could generate spin polarized carrier currents, allowing to envision potential applications in spintronic devices.In RE lanthanide atoms, the 4f states play a minor role on bonding, staying in an atomiclike configuration. Therefore, those atoms bind to their neighboring ones through their outer (5d, 6s, and 6p) atomic valence states [11]. Earlier theoretical investigations generally considered the 4f electrons as core states, with constrained occupations ...

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Structural and electronic properties of3dtransition metal impurities in silicon carbide

Cited by 55 publications

References 30 publications

Microscopic structure of nickel-dopant centers in diamond

Microscopic structure of nickel-dopant centers in diamond

3dtransition metal impurities in diamond: Electronic properties and chemical trends

Lanthanide impurities in wide bandgap semiconductors: A possible roadmap for spintronic devices

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