Alpha-emission channeling investigations of the lattice location of Li in Ge

Wahl, Ulrich; Jahn, S.G.; Restle, M.; Ronning, Carsten; Quintel, H.; Bharuth‐Ram, K.; Hofsäß, H.

doi:10.1016/0168-583x(95)01196-x

Cited by 8 publications

(4 citation statements)

References 18 publications

(41 reference statements)

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“…The initial fit software, called FDD was programmed in FORTRAN in the 1990s by Wahl [36,[38][39][40] and ran under DOS but used already a graphical user interface. Later the same methodology and mathematical routines were transferred to Java by De Vries [53]; a major upgrade by Amorim [54] added functionalities that allow the execution of macros and conveniently perform fits for a whole series of site combinations.…”

Section: Data Fitting Software and Methodologiesmentioning

confidence: 99%

“…EC uses implanted radioactive isotopes and the channeling effects are measured from the charged particles emitted during nuclear decay [33][34][35][36][37]. Most commonly β − particles or conversion electrons (CEs) are used due to the wide choice of suited isotopes but applying α [35,38] or β + emitters [33] is also possible. In EC experiments 2D channeling patterns of outgoing particles are recorded with the use of various types of PSDs [36,[39][40][41].…”

Section: Motivation: the Use Of Two-dimensional Patterns In Channeling Measurementsmentioning

confidence: 99%

“…While the theoretical approaches for describing the channeling of β or α particles are quite different, the final step for the analysis of experimental channeling data, both from RBS/C and EC, is similar and consists in fitting the experimental 1D scans or 2D patterns by a linear combination of theoretical angular yield distributions calculated for impurities on different lattice sites, under assumptions that match the experimental conditions as closely as possible. For the quantitative analysis of 2D emission channeling patterns, chi-square fit routines called FDD (short for "Fit in 2 dimensions") have been briefly reported first in 1996 [38], followed by further remarks in Refs. [36,[39][40]; they were, however, never documented in the literature in detail.…”

Section: Motivation: the Use Of Two-dimensional Patterns In Channeling Measurementsmentioning

confidence: 99%

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

David-Bosne

Wahl

Correia

et al. 2020

Nuclear Instruments and Methods in Physics Research Section B:

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The acquisition of two-dimensional (2D) channeling patterns is gaining increased popularity within the ion beam community. However, with the exception of emission channeling experiments for the lattice location of radioactive impurities, quantitative analysis of such patterns is rarely found. We present a general description of the statistical data analysis methodology for 2D channeling patterns, which consists of comparing experimental data by means of a fit procedure to theoretical yield distributions. The developed software allows for chi-square or maximum likelihood-based fits, optimizing the orientation of the theoretical vs the experimental pattern, as well as the best choice of random level, and providing fractions for the contributions from several theoretical patterns related to different lattice sites. Optionally also the angular resolution can be used as a fit parameter. Use of the software is illustrated by examples of electron emission channeling from 27 Mg in GaN, as well as 4 He RBS channeling from Ge.

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Section: Data Fitting Software and Methodologiesmentioning

confidence: 99%

Section: Motivation: the Use Of Two-dimensional Patterns In Channeling Measurementsmentioning

confidence: 99%

Section: Motivation: the Use Of Two-dimensional Patterns In Channeling Measurementsmentioning

confidence: 99%

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

David-Bosne

Wahl

Correia

et al. 2020

Nuclear Instruments and Methods in Physics Research Section B:

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“…The fit procedures used for this purpose are modified versions of those given in Ref. [15] for the case of alpha emission channeling patterns. The size and shape of the detector pads were taken into account during fitting by averaging over the simulated yield falling within the angular range ͑0.26 ± 3 0.26 ± ͒ of one pad.…”

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confidence: 99%

Direct Evidence for Tetrahedral Interstitial Er in Si

et al. 1997

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We report on the lattice location of Er in Si using the emission channeling technique. The angular distribution of conversion electrons emitted by the decay chain 167 Tm ͑t 1͞2 9.25 d͒ ! 167m Er ͑2.27 s͒ was monitored with a position-sensitive detector following room temperature implantation and annealing up to 950 ± C. Our experiments give direct evidence that Er is stable on tetrahedral interstitial sites in float-zone Si. We also confirm that rare earth atoms strongly interact with oxygen, which finally leads to their incorporation on low-symmetry lattice sites in Czochralski Si. [S0031-9007(97) Rare earth doping of Si is known to result in the formation of luminescent centers and is considered as a possible way to manufacture Si-based optoelectronic devices [1]. Among the various rare earth elements, Er is of special interest since its atomic transition at 1.54 mm matches the absorption minimum of SiO 2 , a highly desirable feature both for signal transmission through glass fiber cables and optical on-chip communication. Luminescence at this wavelength from Er-implanted Si was already established several years ago [2]. Meanwhile Er-based light-emitting diodes operating at room temperature have been reported [3]. The basic understanding of Er luminescence in Si, however, is far from complete. This concerns both the lattice sites of Er and the role of codopants such as O, N, or F, which were found to have a beneficial influence on luminescence yield. Photoluminescence (PL) spectroscopy studies have identified a number of Er-related centers with different crystal surroundings in Si [4]. The most intense PL yield was due to two centers having cubic and axial symmetry, respectively. While the cubic center occurred in both float-zone (FZ) and Czochralski (CZ) Si and was attributed to tetrahedral ͑T ͒ interstitial Er, the center with axial symmetry was observed only in CZ Si and ascribed to Er-O complexes. The existence of tetrahedral interstitial Er would be also in agreement with theoretical studies, which predict that T sites are the most stable sites for all oxidation states of isolated Er atoms in Si [5]. Direct lattice location using the Rutherford backscattering (RBS) channeling technique only suggested substitutional [6] or hexagonal ͑H͒ interstitial Er [7,8]. The reasons for these discrepancies, however, are unclear.To study the lattice sites and damage recovery after rare earth implantation, we have applied conversion electron emission channeling [9] combined with position sensitive detection. Emission channeling makes use of the fact that charged particles emitted from radioactive isotopes in single crystals experience channeling or blocking effects along low-index crystal directions. This leads to an anisotropic particle emission yield from the crystal surface which depends in a characteristic way on the lattice sites occupied by the emitter atoms. While this technique as such is not new and, in case of rare earths, was already used once for the lattice location of 175 Yb in Si [10], we have for the fi...

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