&lt;i&gt;Ab Initio&lt;/i&gt; Study of MgSe Self-Interstitial (Mg&lt;i&gt;&lt;sub&gt;i&lt;/sub&gt; &lt;/i&gt;and Se&lt;i&gt;&lt;sub&gt;i&lt;/sub&gt;&lt;/i&gt;)

Mapasha

Meyer

2016

Journal of Elec Materi

The results of an ab initio modelling of aluminium substitutional impurity (Al Ge), aluminium interstitial in Ge (I Al for the tetrahedral (T) and hexagonal (H) configurations) and aluminium interstitial-substitutional pairs in Ge (I Al Al Ge) are presented. For all calculations, the hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE06) in the framework of density functional theory (DFT) was used. Defects formation energies, charge state transition levels and minimum energy configurations of the Al Ge , I Al and I Al Al Ge were obtained for −2, −1, 0, +1 and +2 charge states. The calculated formation energy shows that for the neutral charge state, the I Al is energetically more favourable in the T than the H configuration. The I Al Al Ge forms with forma

Section: Computational Detailsmentioning

confidence: 99%

Ab␣Initio Study of Aluminium Impurity and Interstitial-Substitutional Complexes in Ge Using a Hybrid Functional (HSE)

Mapasha

Meyer

2016

Journal of Elec Materi

“…In this hybrid approach, the short-range exchange potential is calculated by mixing a 25 percent fraction of nonlocal Hartree-Fock exchange with the generalized gradient approximation (GGA) functional of Perdew, Burke, and Ernzerhof (PBE) [20]. The hybrid functionals with DFT have been known to accurately predict band gaps of several materials [21,22,23] which the local density approximation (LDA) and the GGA fail to estimate accurately [21,24,25]. In addition, the HSE06 has been used to predict accurate band structures and effective masses for InP, InAs, and InSb, where the results are in agreement with experimental data [26].…”

Section: Computational Detailsmentioning

confidence: 99%

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

Nuclear Instruments and Methods in Physics Research Section B:

Omotoso

Danga

et al. 2017

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.

“…In contrast to the local density approximation (LDA) and the GGA that tend to underestimate the band gap of semiconductors [22,12,23], the HSE06 functional gives an excellent description of the electronic band gap and charge state transition properties for a wide range of the defects in group-IV semiconductors [22,9,7]. For the past decade, the study and prediction of the electronic properties of materials with the f orbital valence shell was difficult due to the fact that the f orbital is highly localized.…”

Section: Computational Detailsmentioning

confidence: 99%

“…which is lying deep in the band gap at E V + 0.18 eV. The interaction energy between two electrons in a two-level defect is referred to as Hubbard U [23,35]. A defect often has a negative-U (U < 0) if the atomic position of the defect depends sensitively on its charge state.…”

Section: Charge State Transition Levels Of Re Interstitials In Gementioning

confidence: 99%

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

Andrew

Meyer

2016

Journal of Elec Materi

In this work, the results of density functional theory calculations for rare earth (Ce, Pr, Eu and Er) interstitials in Ge are presented. We employed the hybrid functional of Heyd, Scuseria, and Ernzerhof (HSE06) for all the calculations. We calculated the formation energies and charge state transition levels for the tetrahedral (T) and hexagonal (H) configurations of the Ce, Pr, Eu and Er interstitials in Ge. While for the T configuration, the charge states of the Ce and Pr did not induce any thermodynamic accessible transition state level within the band gap of Ge, for both the T and H configurations the Eu and Er interstitials in Ge induce deep levels in the band gap. The H configuration of the Ce interstitial