Ab initio study of metastability of Eu3+ defect complexes in GaN

Ouma, Cecil Naphtaly Moro; Meyer, W.E.

doi:10.1016/j.physb.2013.11.004

Cited by 8 publications

(4 citation statements)

References 30 publications

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“…Er Ga -(V N ) basal was also reported to have the (0/−) level at 0.02 eV above the CBM [51]. Our results for Eu Ga -V N and Eu Ga -V Ga are, however, qualitatively different from those reported by other groups [35,37], which can be ascribed to the different methods used in the current work and the previously reported studies.…”

Section: B Defect Complexes Of Eu and Native Defectscontrasting

confidence: 97%

“…On the theory side, calculations for Eu-doped GaN were carried out by several research groups using densityfunctional theory (DFT) based methods, including the local-density approximation (LDA) or self-interaction corrected LDA, the generalized gradient approximation (GGA), and GGA+U , and LDA+U within a DFT-based tight-binding approach [33][34][35][36][37][38][39][40][41]. These studies provided useful information on the structural and electronic properties but limited data on defect structure and energetics.…”

Section: Introductionmentioning

confidence: 99%

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Tuning the valence and concentration of europium and luminescence centers in GaN through co-doping and defect association

Hoang

2020

Preprint

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Defect physics of Eu-doped GaN is investigated using first-principles hybrid density-functional defect calculations. This includes the interaction between the rare-earth dopant and native defects (Ga and N vacancies) and other impurities (O, Si, C, H, and Mg) unintentionally present or intentionally incorporated into the host material. While the trivalent Eu 3+ ion is often found to be predominant when Eu is incorporated at the Ga site in wurtzite GaN, the divalent Eu 2+ is also stable and found to be predominant in a small range of Fermi-level values in the band-gap region. The Eu 2+ /Eu 3+ ratio can be tuned by tuning the position of Fermi level and through defect association. We find co-doping with oxygen can facilitate the incorporation of Eu into the lattice. The unassociated EuGa is an electrically and optically active defect center and its behavior is profoundly impacted by local defect-defect interaction. Among the Eu-related defects, we identify complexes such as EuGa-ON, EuGa-SiGa, EuGa-Hi, EuGa-MgGa, and EuGa-ON-MgGa as efficient defect-related Eu 3+ centers for non-resonant excitation. This work calls for a re-assessment of certain assumptions regarding specific defect configurations previously made for Eu-doped GaN and further investigation into the origin of the photoluminescence hysteresis observed in (Eu,Mg)-doped samples.

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Section: B Defect Complexes Of Eu and Native Defectscontrasting

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Tuning the valence and concentration of europium and luminescence centers in GaN through co-doping and defect association

Hoang

2020

Preprint

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“…[13][14][15][16][17] Within condensed matter science, rare-earth (RE) elements receive a lot of attention as optical dopants, as they give rise to very sharp emission lines, for a wide variety of wavelengths from UV to IR. [18][19][20][21][22][23] Furthermore, their filled d-shell shields the long lived excited states. In particular Eu and Gd are of great interest as both have a half-filled 4f shell.…”

Section: Introductionmentioning

confidence: 99%

Can europium atoms form luminescent centres in diamond: A combined theoretical–experimental study

Vanpoucke

Nicley

Raymakers

et al. 2019

Diamond and Related Materials

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The incorporation of Eu into the diamond lattice is investigated in a combined theoreticalexperimental study. The large size of the Eu ion induces a strain on the host lattice, which is minimal for the Eu-vacancy complex. The oxidation state of Eu is calculated to be 3+ for all defect models considered. In contrast, the total charge of the defect-complexes is shown to be negative: −1.5 to −2.3 electron. Hybrid-functional electronic-band-structures show the luminescence of the Eu defect to be strongly dependent on the local defect geometry. The 4-coordinated Eu substitutional dopant is the most promising candidate to present the typical Eu 3+ luminescence, while the 6-coordinated Eu-vacancy complex is expected not to present any luminescent behaviour. Preliminary experimental results on the treatment of diamond films with Eu-containing precursor indicate the possible incorporation of Eu into diamond films treated by drop-casting. Changes in the PL spectrum, with the main luminescent peak shifting from approximately 614 nm to 611 nm after the growth plasma exposure, and the appearance of a shoulder peak at 625 nm indicate the potential incorporation. Drop-casting treatment with an electronegative polymer material was shown not to be necessary to observe the Eu signature following the plasma exposure, and increased the background luminescence.

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“…As earlier mentioned, even though metastable defects have attracted the attention of experiments, theoretical investigations have mainly focussed on stable defects and defect complexes. Very few theoretical studies have attempted to investigate defect metastability [23,24].…”

Section: Introductionmentioning

confidence: 99%

The carbon-substitutional–carbon-interstitial (CsCi) defect pair in silicon from hybrid functional calculations

Ouma

Meyer

2016

Computational Materials Science

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Ab initio study of metastability of Eu3+ defect complexes in GaN

Cited by 8 publications

References 30 publications

Tuning the valence and concentration of europium and luminescence centers in GaN through co-doping and defect association

Tuning the valence and concentration of europium and luminescence centers in GaN through co-doping and defect association

Can europium atoms form luminescent centres in diamond: A combined theoretical–experimental study

The carbon-substitutional–carbon-interstitial (CsCi) defect pair in silicon from hybrid functional calculations

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