Rare Earth Interstitials in Ge: A Hybrid Density Functional Theory Study

Igumbor, Emmanuel; Andrew, Richard Charles; Meyer, W.E.

doi:10.1007/s11664-016-5062-8

Cited by 10 publications

(10 citation statements)

References 35 publications

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“…Metastability of charge states in a point defect (vacancy, interstitials, interstitialcomplex, vacancy-complexes) has been reported for Si [49,50], Ge [8,6,51] and…”

Section: Metastability Of B and N Vacancy-complexes In 4h-sicmentioning

confidence: 99%

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

Igumbor¹,

Olaniyan²,

Mapasha³

et al. 2018

J. Phys.: Condens. Matter

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Electrically active induced energy levels in semiconductor devices could be beneficial to the discovery of an enhanced p or n-type semiconductor. Nitrogen (N) implanted into 4H-SiC is a high energy process that produced high defect concentrations which could be removed during dopant activation annealing. On the other hand, boron (B) substituted for silicon in SiC causes a reduction in the number of defects. This scenario leads to a decrease in the dielectric properties and induced deep donor and shallow acceptor levels. Complexes formed by the N, such as the nitrogen-vacancy centre, have been reported to play a significant role in the application of quantum bits. In this paper, results of charge states thermodynamic transition level of the N and B vacancy-complexes in 4H-SiC are presented. We explore complexes where substitutional N[Formula: see text]/N[Formula: see text] or B[Formula: see text]/B[Formula: see text] sits near a Si (V[Formula: see text]) or C (V[Formula: see text]) vacancy to form vacancy-complexes (N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text]). The energies of formation of the N related vacancy-complexes showed the N[Formula: see text]V[Formula: see text] to be energetically stable close to the valence band maximum in its double positive charge state. The N[Formula: see text]V[Formula: see text] is more energetically stable in the double negative charge state close to the conduction band minimum. The N[Formula: see text]V[Formula: see text] on the other hand, induced double donor level and the N[Formula: see text]V[Formula: see text] induced a double acceptor level. For B related complexes, the B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text] were energetically stable in their single positive charge state close to the valence band maximum. As the Fermi energy is varied across the band gap, the neutral and single negative charge states of the B[Formula: see text]V[Formula: see text] become more stable at different energy levels. B and N related complexes exhibited charge state controlled metastability behaviour.

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“…Metastability of charge states in a point defect (vacancy, interstitials, interstitialcomplex, vacancy-complexes) has been reported for Si [49,50], Ge [8,6,51] and…”

Section: Metastability Of B and N Vacancy-complexes In 4h-sicmentioning

confidence: 99%

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

Igumbor¹,

Olaniyan²,

Mapasha³

et al. 2018

J. Phys.: Condens. Matter

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“…However, the HSE06 functional has been used to predict accurately the electronic band gap and improve charge state transition properties for group−IV semiconductors [2,12,30]. According to our previous reports [10,20], the modelling and prediction of the electronic properties of material with the f orbital valence shell was difficult, because the f orbital is highly localized. Recently, the hybrid functional has been successfully used to predict the electronic and band gap properties of several materials with the f orbital in the valence shell [10,31,32].…”

Section: Computational Detailsmentioning

confidence: 99%

“…The Tm 3+ and Ce 3+ interstitials in Ge are found to exhibit charge state negative-U ordering [20,10].…”

Section: Introductionmentioning

confidence: 99%

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Rare earth substitutional impurities in germanium: A hybrid density functional theory study

Igumbor

Omotoso

Tunhuma

et al. 2017

Nuclear Instruments and Methods in Physics Research Section B:

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The Heyd, Scuseria, and Ernzerhof (HSE06) hybrid functional by means of density functional theory has been used to modelled the electronic and structural properties of rare earth (RE) substitutional impurities in germanium (RE Ge). The formation and charge state transition energies for the RE Ge (RE = Ce, Pr, Er and Eu) were calculated. The energy of formation for the neutral charge state of the RE Ge lies between −0.14 and 3.13 eV. The formation energy result shows that the Pr dopant in Ge (Pr Ge) has the lowest formation energy of −0.14 eV, and is most energetically favourable under equilibrium conditions. The RE Ge induced charge state transition levels within the band gap of Ge. Shallow acceptor levels were induced by both the Eu (Eu Ge) and Pr (Pr Ge) dopants in Ge. The Ce Ge and Er Ge exhibited properties of negative-U ordering with effective-U values of −0.85 and −1.07 eV, respectively.

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“…RE substitutional, interstitials and vacancy−complex related defects in Si and Ge have been studied with emphasis on the induced defect levels [6,7,8,9,10]. Ge has a narrow band gap of 0.78 eV at 0 K, and is being considered as a suitable material for next generation high performance microelectronics devices [11,12,13]: such as mobility−enhanced metal−oxide−semiconductor field−effect transistors (MOSFETs). In addition, Ge provides an alternative solution for the search of materials that required high mobility channels.…”

Section: Introductionmentioning

confidence: 99%

Rare earth interstitial-complexes in Ge: Hybrid density functional studies

Igumbor

Omotoso

Danga

et al. 2017

Nuclear Instruments and Methods in Physics Research Section B:

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We present results of the structural, energetic and electronic properties of rare earth (RE) interstitial−complexes in Ge (RE Ge Ge i ; for RE: Ce, Pr, Eu, Er and Tm). We used the Heyd, Scuseria, and Ernzerhof (HSE06) hybrid functional within the framework of density functional theory for all calculations. The energy of formation and charge state transition levels of RE Ge Ge i complexes were obtained. For the neutral charge state, the results of the formation energy of the RE Ge Ge i , were between 0.21 and 8.14 eV. Amongst the RE Ge Ge i , while the Ce Ge Ge i was energetically the most favourable with a binding energy of 3.90 eV, Tm Ge Ge i and Er Ge Ge i were not stable with respect to their binding energies. The Ce Ge Ge i induced deep donor level with negative-U ordering, the Pr Ge Ge i induced shallow levels close to the valence band maximum and the Eu Ge Ge i induced a shallow single donor level.

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Rare Earth Interstitials in Ge: A Hybrid Density Functional Theory Study

Cited by 10 publications

References 35 publications

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

Rare earth substitutional impurities in germanium: A hybrid density functional theory study

Rare earth interstitial-complexes in Ge: Hybrid density functional studies

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