A generalized fitting tool for analysis of two-dimensional channeling patterns

David-Bosne, E.; Wahl, Ulrich; Correia, J. G.; Lima, T. A. L.; Vantomme, André; Pereira, L. M. C.

doi:10.1016/j.nimb.2019.10.029

Cited by 10 publications

(8 citation statements)

References 53 publications

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“…More experimental details regarding EC experiments with 27 Mg can be found in refs , and in the Supporting Information. The major lattice sites can be identified by fitting the experimentally observed emission yields by linear combinations of theoretical patterns ,, calculated for specific positions of the emitter atoms in the lattice. For that purpose, the many-beam approach , was used to calculate the expected emission yields for substitutional ( S ) as well as around 250 interstitial sites in the diamond structure, which are obtained by displacing from the S position along ⟨111⟩, ⟨100⟩, or ⟨110⟩ directions in steps of around 0.04 Å (Figure S3 of the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Magnesium-Vacancy Optical Centers in Diamond

et al. 2022

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We provide the first systematic characterization of the structural and photoluminescence properties of optically active centers fabricated upon implantation of 30–100 keV Mg+ ions in synthetic diamond. The structural configurations of Mg-related defects were studied by the electron emission channeling technique for short-lived, radioactive 27Mg implantations at the CERN-ISOLDE facility, performed both at room temperature and 800 °C, which allowed the identification of a major fraction of Mg atoms (∼30 to 42%) in sites which are compatible with the split-vacancy structure of the MgV complex. A smaller fraction of Mg atoms (∼13 to 17%) was found on substitutional sites. The photoluminescence emission was investigated both at the ensemble and individual defect level in the 5–300 K temperature range, offering a detailed picture of the MgV-related emission properties and revealing the occurrence of previously unreported spectral features. The optical excitability of the MgV center was also studied as a function of the optical excitation wavelength to identify the optimal conditions for photostable and intense emission. The results are discussed in the context of the preliminary experimental data and the theoretical models available in the literature, with appealing perspectives for the utilization of the tunable properties of the MgV center for quantum information processing applications.

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Section: Resultsmentioning

confidence: 99%

Magnesium-Vacancy Optical Centers in Diamond

et al. 2022

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“…[ 36–37 ] The major lattice sites can be identified by fitting the experimentally observed angular‐dependent emission yields by linear combinations of theoretically expected patterns for specific positions in the lattice. [ 36–37,39 ]…”

Section: Introductionmentioning

confidence: 99%

Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN

Wahl

Correia

Costa

et al. 2021

Adv Elect Materials

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Despite the renewed interest in ion implantation doping of GaN, efficient electrical activation remains a challenge. The lattice location of 27Mg is investigated in GaN of different doping types as a function of implantation temperature and fluence at CERN's ISOLDE facility. The amphoteric nature of Mg is elucidated, i.e., the concurrent occupation of substitutional Ga and interstitial sites: following room temperature ultra‐low fluence (≈2 × 1010 cm−2) implantation, the interstitial fraction of Mg is highest (20–24%) in GaN pre‐doped with stable Mg during growth, and lowest (2–6%) in n‐GaN:Si, while undoped GaN shows an intermediate interstitial fraction of 10–12%. Both for p‐ and n‐GaN prolonged implantations cause interstitial 27Mg to approach the levels found for undoped GaN. Implanting above 400 °C progressively converts interstitial Mg to substitutional Ga sites due to the onset of Mg interstitial migration (estimated activation energy 1.5–2.3 eV) and combination with Ga vacancies. In all sample types, implantations above a fluence of 1014 cm−2 result in >95% substitutional Mg. Ion implantation is hence a very efficient method to introduce Mg into substitutional Ga sites, i.e., challenges toward high electrical activation of implanted Mg are not related to lack of substitutional incorporation.

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“…The corresponding angular-dependent emission patterns are recorded by means of a two-dimensional position-sensitive detector (PSD) [35,36] which is placed at a suitable distance from the sample. The major lattice sites can be identified by fitting the experimentally observed emission yields by linear combinations of theoretically expected patterns calculated for specific positions of the emitter atoms in the lattice [35,36,39].…”

Section: Methodsmentioning

confidence: 99%

“…For the analysis of the experimental patterns, these were fitted [35,39] by a linear combination of substitutional and interstitial 11 Be emitter atoms. In order to identify the most likely interstitial Be i site, its position was varied and the chi square of fit used as a criterium.…”

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Direct evidence of Be as an amphoteric dopant in GaN

et al. 2022

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The interest in Be as an impurity in GaN stems from the challenge to understand why GaN can be doped ptype with Mg, while this does not work for Be. While theory has actually predicted an acceptor level for Be that is shallower than Mg, it was also argued that Be is not a suitable acceptor because its amphoteric nature, i.e. its tendency to occupy substitutional Ga as well as interstitial sites, would be considerably more pronounced than for Mg and hence lead to self-compensation. Using the emission channeling technique at the ISOLDE/CERN facility, we determined the lattice location of 11 Be (t1/2=13.8 s) in different doping types of GaN as a function of implantation temperature. We find within an accuracy of 0.08 Å that the location of interstitial Be is the one predicted by theory. The room temperature interstitial fraction of 11 Be was correlated with the GaN doping type, being highest (up to ~80%) in p-type and lowest in n-GaN, thus giving direct evidence for the amphoteric character of Be. We find that interstitial 11 Be fractions are generally much higher than for Mg, which confirms that indeed self-compensation should be considerably more pronounced for Be. With rising implantation temperature, an increasing conversion of interstitial to substitutional Be is observed, involving at least two clearly identifiable steps at 50-150 °C and 350-500 °C. This suggests that the migration of interstitial Be may be subject to two different activation energies.

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A generalized fitting tool for analysis of two-dimensional channeling patterns

Cited by 10 publications

References 53 publications

Magnesium-Vacancy Optical Centers in Diamond

Magnesium-Vacancy Optical Centers in Diamond

Lattice Location Studies of the Amphoteric Nature of Implanted Mg in GaN

Direct evidence of Be as an amphoteric dopant in GaN

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