Manganese impurities in boron nitride

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

doi:10.1063/1.2266930

Cited by 22 publications

(21 citation statements)

References 15 publications

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“…All those approximations and convergence criteria have been shown to provide an accurate description of several defect centers in semiconductors. 32,33 The formation energy of a complex in a q charge state ͑E f q ͒ was computed by…”

Section: Methodsmentioning

confidence: 99%

Electronic properties and hyperfine fields of nickel-related complexes in diamond

Larico

Justo²,

Machado³

et al. 2009

Phys. Rev. B

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We carried out a first-principles investigation on the microscopic properties of nickel-related defect centers in diamond. Several configurations, involving substitutional and interstitial nickel impurities, have been considered either in isolated configurations or forming complexes with other defects, such as vacancies and boron and nitrogen dopants. The results, in terms of spin, symmetry, and hyperfine fields, were compared with the available experimental data on electrically active centers in synthetic diamond. Several microscopic models, previously proposed to explain those data, have been confirmed by this investigation, while some models could be discarded. We also provided insights into the microscopic structure of several of those centers.

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Section: Methodsmentioning

confidence: 99%

Electronic properties and hyperfine fields of nickel-related complexes in diamond

Larico

Justo²,

Machado³

et al. 2009

Phys. Rev. B

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“…It has been suggested that TMs occupy both substitutional and center-bond sites in Ge. 26 Assali and co-worker 27 also found that Mn is energetically more favorable in a divacancy site as compared to the B site in boron nitride (BN) and forms splitvacancy defects. In SiC, it is not clear if the 4d and 5d TMs with larger ionic radii prefer the Si site to form isolated substitutional defects or a split-vacancy site as in BN.…”

Section: Nbmentioning

confidence: 99%

Electron paramagnetic resonance and theoretical studies of Nb in 4H- and 6H-SiC

Són¹,

Trinh²,

Gällström³

et al. 2012

Journal of Applied Physics

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High purity silicon carbide (SiC) materials are of interest from high-power high temperature applications across recent photo-voltaic cells to hosting solid state quantum bits, where the tight control of electrically, optically, and magnetically active point defects is pivotal in these areas. 4H-and 6H-SiC substrates are grown at high temperatures and the incorporation of transition metal impurities is common. In unintentionally Nb-doped 4H-and 6H-SiC substrates grown by high-temperature chemical vapor deposition, an electron paramagnetic resonance (EPR) spectrum with C 1h symmetry and a clear hyperfine (hf) structure consisting of ten equal intensity hf lines was observed. The hf structure can be identified as due to the interaction between the electron spin S ¼ 1/2 and the nuclear spin of 93 Nb. Additional hf structures due to the interaction with three Si neighbors were also detected. In 4H-SiC, a considerable spin density of $37.4% was found on three Si neighbors, suggesting the defect to be a complex between Nb and a nearby carbon vacancy (V C ). Calculations of the , support previous reported results that Nb preferentially forms an asymmetric split-vacancy (ASV) defect. In both 4H-and 6H-SiC, only one Nb-related EPR spectrum has been observed, supporting the prediction from calculations that the hexagonal-hexagonal defect configuration of the ASV complex is more stable than others. V C 2012 American Institute of Physics. [http://dx

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“…[18]. In order to get that, we considered an alignment of the RE 5d-related energy levels, according to the average energy of spin up and down states.…”

Section: (B)mentioning

confidence: 99%

mentioning

confidence: 99%

“…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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Manganese impurities in boron nitride

Abstract: Effects of nitrogen vacancies on transition-metal-doped GaN: An ab initio studyManganese-induced long-range lattice disorder and vacancy formation in metal-organic chemical vapor deposition grown and ion-implanted Ga 1 − x Mn x N

Cited by 22 publications

References 15 publications

Electronic properties and hyperfine fields of nickel-related complexes in diamond

Electronic properties and hyperfine fields of nickel-related complexes in diamond

Electron paramagnetic resonance and theoretical studies of Nb in 4H- and 6H-SiC

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

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