Interactions hyperfines du centre F<sup>+</sup> dans ZnO

González, C. E.; Galland, Daniel; Hervé, A.

doi:10.1002/pssb.2220720134

Cited by 71 publications

(35 citation statements)

References 17 publications

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“…This is supported by the observations that the isolated Zn vacancies 6 and probably isolated interstitials on both sublattices 12 are mobile well below room temperature. On the other hand, the introduction rate of the O vacancies suggests that they are primary defects, and comparison to results obtained from EPR measurements, 11,13 which show that the isolated O vacancy is stable at room temperature, suggests that the O vacancies observed in this work are isolated.…”

Section: ͑9͒supporting

confidence: 74%

“…12,13 Signals from both Zn and O interstitials 12 and from Zn vacancies [6][7][8][9] have been observed only at temperatures well below the room temperature-i.e., at 4-90 K. The disparition of the signals has been reported to occur at several stages between 110 K and 280 K. Only the O vacancies have been observed with EPR at room temperature. 8,10,11,13 The photoluminescence spectrum of ZnO typically exhibits a green luminescence ͑GL͒ band similar to the yellow luminescence in GaN. 14 Both the Zn ͑Refs.…”

Section: Introductionmentioning

confidence: 97%

“…Defects introduced by electron and neutron irradiation in ZnO have been studied by electron paramagnetic resonance ͑EPR͒ in the past [6][7][8][9][10][11] and also quite recently. 12,13 Signals from both Zn and O interstitials 12 and from Zn vacancies [6][7][8][9] have been observed only at temperatures well below the room temperature-i.e., at 4-90 K. The disparition of the signals has been reported to occur at several stages between 110 K and 280 K. Only the O vacancies have been observed with EPR at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Introduction and recovery of point defects in electron-irradiated ZnO

et al. 2005

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We have used positron annihilation spectroscopy to study the introduction and recovery of point defects in electron-irradiated n-type ZnO. The irradiation ͑E el = 2 MeV, fluence 6 ϫ 10 17 cm −2 ͒ was performed at room temperature, and isochronal annealings were performed from 300 to 600 K. In addition, monochromatic illumination of the samples during low-temperature positron measurements was used in identification of the defects. We distinguish two kinds of vacancy defects: the Zn and O vacancies, which are either isolated or belong to defect complexes. In addition, we observe negative-ion-type defects, which are attributed to O interstitials or O antisites. The Zn vacancies and negative ions act as compensating centers and are introduced at a concentration ͓V Zn ͔Ӎc ion Ӎ 2 ϫ 10 16 cm −3 . The O vacancies are introduced at a 10-times-larger concentration ͓V O ͔Ӎ3 ϫ 10 17 cm −3 and are suggested to be isolated. The O vacancies are observed as neutral at low temperatures, and an ionization energy of 100 meV could be fitted with the help of temperature-dependent Hall data, thus indicating their deep donor character. The irradiation-induced defects fully recover after the annealing at 600 K, in good agreement with electrical measurements. The Zn vacancies recover in two separate stages, indicating that the Zn vacancies are parts of two different defect complexes. The O vacancies anneal simultaneously with the Zn vacancies at the later stage, with an activation energy of E V,O m = 1.8± 0.1 eV. The negative ions anneal out between the two annealing stages of the vacancies.

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Section: ͑9͒supporting

confidence: 74%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Introduction and recovery of point defects in electron-irradiated ZnO

et al. 2005

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“…In 2002 stimulated by a theoretical work of Van de Walle [51] hydrogen could be identified as a shallow donor too [52]. The "1.96" resonance has been attributed for a long time with the singly ionized charge state of the oxygen vacancy (F + -center) [53][54][55], although the F + -center could only be detected after electron or neutron irradiation of ZnO [56][57][58]. As to acceptor related centers (apart from transition metal elements which will not be considered here) three of them were detected again after particle irradiation of undoped ZnO [59][60][61][62][63].…”

Section: Magnetic Resonance Investigationsmentioning

confidence: 99%

Bound exciton and donor–acceptor pair recombinations in ZnO

Meyer

Alves

Hofmann

et al. 2004

Physica Status Solidi (b)

1,608

153

1,169

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The optical properties of excitonic recombinations in bulk, n-type ZnO are investigated by photoluminescence (PL) and spatially resolved cathodoluminescence (CL) measurements. At liquid helium temperature in undoped crystals the neutral donor bound excitons dominate in the PL spectrum. Two electron satellite transitions (TES) of the donor bound excitons allow to determine the donor binding energies ranging from 46 to 73 meV. These results are in line with the temperature dependent Hall effect measurements. In the as-grown crystals a shallow donor with an activation energy of 30 meV controls the conductivity. Annealing annihilates this shallow donor which has a bound exciton recombination at 3.3628 eV. Correlated by magnetic resonance experiments we attribute this particular donor to hydrogen. The Al, Ga and In donor bound exciton recombinations are identified based on doping and diffusion experiments and using secondary ion mass spectroscopy. We give a special focus on the recombination around 3.333 eV, i.e. about 50 meV below the free exciton transition. From temperature dependent measurements one obtains a small thermal activation energy for the quenching of the luminescence of 10 ± 2 meV despite the large localization energy of 50 meV. Spatially resolved CL measurements show that the 3.333 eV lines are particularly strong at crystal irregularities and occur only at certain spots hence are not homogeneously distributed within the crystal contrary to the bound exciton recombinations. We attribute them to excitons bound to structural defects (Y-line defect) very common in II-VI semiconductors. For the bound exciton lines which seem to be correlated with Li and Na doping we offer a different interpretation. Li and Na do not introduce any shallow acceptor level in ZnO which otherwise should show up in donor -acceptor pair recombinations. Nitrogen creates a shallow acceptor level in ZnO. Donor -acceptor pair recombination with the 165 meV deep N-acceptor is found in nitrogen doped and implanted ZnO samples, respectively. In the best undoped samples excited rotational states of the donor bound excitons can be seen in low temperature PL measurements. At higher temperatures we also see the appearance of the excitons bound to the B-valence band, which are approximately 4.7 meV higher in energy.

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“…This seems to be o.k. since electron paramagnetic resonance (EPR) experiments required optical excitation for the detection of the V O + charge state [7][8][9]. Optically detected magnetic resonance (ODMR) experiments have shown that the V O is the cause of one of the "green" emissions in ZnO [10].…”

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confidence: 99%

Negative U‐properties of the oxygen‐vacancy in ZnO

Pfisterer

Sann

Hofmann

et al. 2006

Phys. Status Solidi (c)

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It is shown that the intensity of the oxygen vacancy (V O ) related emission in ZnO at 2.45 eV correlates to the concentration of the donor level E4. E4 is located 530 meV below the conduction band and attributed to the V O 0/++ recharging. Deep level transient spectroscopy (DLTS) experiments with optical excitation locate the V O 2+/+ level position 140 meV below the conduction band and give evidence for the "negative-U" properties of the oxygen vacancies in ZnO. 1 Introduction Interest in ZnO has grown during the rescent years due to progress in crystal growth and its unique optical and electrical properties. ZnO has a direct bandgap of about 3.3 eV at room temperature and can be thought of as alternative to GaN opto-electronic devices for the blue spectral range. The reports on successful p-type doping have led to even higher expectations about the materials potential applications in electronics [1][2][3]. In addition, when doped with Mn, ZnO has been reported to exhibit ferromagentic behavior above room temperature [4], making it a prospective material for spintronics.Point defects have important effects on the optical and electronic properties of semiconductors. Their understanding is needed for a description of the specific properties of the material. In this paper we concentrate on the optical and electrical properties of the oxygen vacancy (V O ) in ZnO. Theoretical estimates for the level positions have been made recently by two independent groups [5,6]. In both cases neative-U ordering was predicted, implying that the (2+/+) lies above the (+/0) in the bandgap. Van de Walle [5] calculated the (0/++) transition level at ~ E v + 2.7 eV, the (2+/+) level close to the conduction band (E v + 3.3 eV) and the (+/0) level at ~ E v + 2.0 eV, while Lany [6] in his calculations obtained the respective level positions approximately 1 eV lower in energy.If the predicted negative-U behaviour is correct the V O + charge state is thermodynamically unstable. This seems to be o.k. since electron paramagnetic resonance (EPR) experiments required optical excitation for the detection of the V O + charge state [7][8][9]. Optically detected magnetic resonance (ODMR) experiments have shown that the V O is the cause of one of the "green" emissions in ZnO [10]. It originates from a spin-triplet excited state (S = 1) of the neutral vacancy V O 0 , and has its intensity maxmum at 2.45 eV (~506 nm) and a halfwidth of 450 meV at a temperature of 4 K.

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Interactions hyperfines du centre F⁺ dans ZnO

Cited by 71 publications

References 17 publications

Introduction and recovery of point defects in electron-irradiated ZnO

Introduction and recovery of point defects in electron-irradiated ZnO

Bound exciton and donor–acceptor pair recombinations in ZnO

Negative U‐properties of the oxygen‐vacancy in ZnO

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Interactions hyperfines du centre F+ dans ZnO

Cited by 71 publications

References 17 publications

Introduction and recovery of point defects in electron-irradiated ZnO

Introduction and recovery of point defects in electron-irradiated ZnO

Bound exciton and donor–acceptor pair recombinations in ZnO

Negative U‐properties of the oxygen‐vacancy in ZnO

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Interactions hyperfines du centre F⁺ dans ZnO