Density of Mn interstitials in (Ga,Mn)As epitaxial layers determined by anomalous x-ray diffraction

Holý, V.; Martí, X.; Horák, Lukáš; Caha, Ondřej; Novák, V.; Cukr, M.; Schülli, Tobias U.

doi:10.1063/1.3514240

Cited by 6 publications

(4 citation statements)

References 17 publications

(16 reference statements)

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“…The concentration of the substitutional Mn (c sub = (8.2 ± 1.1)%) was determined by anomalous x-ray diffraction method performed on the same samples. 11 Figure 1 (a) shows the diffraction curves of sample B-2 (20x etched&annealed) measured in diffractions 002, 004 and 224 along with their fits assuming a (Ga,Mn)As layer with homogeneous concentrations of Mn interstitial and substitutional atoms. The quality of the fit is reasonably good, however a close inspection in Fig.…”

Section: Results Of the Diffraction Measurementsmentioning

confidence: 99%

“…From this dependence it is possible to determine the difference of the densities of Mn atoms placed in non-equivalent interstitial lattice positions. 11 Another x-ray based methods for the investigation of the lattice positions of Mn atoms in (Ga,Mn)As are the x-ray standing wave method (XRSW) and x-ray absorption spectroscopy (methods extended x-ray absorption fine structure -EXAFS and x-ray absorption near-edge spectroscopy -XANES). The former method uses the effect of x-ray standing wave produced by diffraction in the GaAs substrate.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion of Mn interstitials in (Ga,Mn)As epitaxial layers

et al. 2011

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Magnetic properties of thin (Ga,Mn)As layers improve during annealing by out-diffusion of interstitial Mn ions to a free surface. Out-diffused Mn atoms participate in the growth of a Mn-rich surface layer and a saturation of this layer causes an inhibition of the out-diffusion. We combine high-resolution x-ray diffraction with x-ray absorption spectroscopy and a numerical solution of the diffusion problem for the study of the out-diffusion of Mn interstitials during a sequence of annealing steps. Our data demonstrate that the out-diffusion of the interstitials is substantially affected by the internal electric field caused by an inhomogeneous distribution of charges in the (Ga,Mn)As layer.

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Section: Results Of the Diffraction Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffusion of Mn interstitials in (Ga,Mn)As epitaxial layers

et al. 2011

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“…MEAD has been used to analyze the distribution of Mn in epitaxial layers of (Ga,Mn)As, successfully determining the densities of Mn ions in substitutional and interstitial positions in the GaAs lattice (Holy et al 2010, Horak 2014. Data were collected in the range 6.4 to 6.7 keV, around the Mn K-edge.…”

Section: Thin Films On Substratementioning

confidence: 99%

The use of anomalous x-ray diffraction as a tool for the analysis of compound semiconductors

Többens

Schorr

2017

Semicond. Sci. Technol.

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We provide a review about the current and previous use of anomalous diffraction of X-rays in the analysis of compound semiconductors. Among the large number of available techniques, those that have been used in successful experiments on this class of compounds are identified. An exhaustive overview of the compound semiconductor systems studied successfully is given and the kind of results derived in the experiments is discussed.

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“…In pioneering work, using X-ray scattering techniques to probe dopant lattice location, comparable T Ga and T As occupancies have been reported. 10 13 Solving this inconsistency would allow for a better understanding of the mechanisms of electric and magnetic compensation by Mn i which, as introduced above, plays a central role in the behavior of (Ga,Mn)As.…”

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Identification of the interstitial Mn site in ferromagnetic (Ga,Mn)As

Lima

Wahl

Augustyns

et al. 2015

Applied Physics Letters

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We determined the lattice location of Mn in ferromagnetic (Ga,Mn)As using the electron emission channeling technique. We show that interstitial Mn occupies the tetrahedral site with As nearest neighbors (T As ) both before and after thermal annealing at 200 °C, whereas the occupancy of the tetrahedral site with Ga nearest neighbors (T Ga ) is negligible. T As is therefore the energetically favorable site for interstitial Mn in isolated form as well as when forming complexes with substitutional Mn. These results shed new light on the long standing controversy regarding T As versus T Ga occupancy of interstitial Mn in (Ga,Mn)As.[http://dx.doi.org/10.1063/1.4905556] a lino.pereira@fys.kuleuven.be (Ga,Mn)As has become the model system, in which to explore the physics of carrier-mediated ferromagnetism in semiconductors and the associated spintronic phenomena. 1,2In particular, as the most widely studied dilute magnetic semiconductor (DMS), (Ga,Mn)As is the perfect example of how the magnetic behavior of DMS materials is strongly influenced by local structure. In typical high Curie temperature (T C ) (Ga,Mn)As thin films (several % Mn regime), the majority of the Mn atoms substitute for Ga (Mn s ), while a minority fraction (several % of all Mn) occupies interstitial sites (Mn i ).3,4 Mn s provides both the localized magnetic moment and the itinerant hole that mediates the magnetic coupling, whereas Mn i has a twofold compensating effect: (i) magnetically, as Mn i -Mn s pairs couple antiferromagnetically and (ii) electrically, since double donor Mn i compensates Mn s acceptors.3 For a given Mn s concentration, Mn i therefore determines the hole concentration, the Fermi level and the effective Mn s concentration (of non-compensated Mn s moments), all of which define the magneto-electronic behavior of (Ga,Mn)As. The existence of such a crucial role of Mn i is clearly reflected in the effect of the Mn i concentration on the two relevant figures of merit: T C and magnetization. 3−5 Despite this central role in the understanding of (Ga,Mn)As, and, consequently, of Mn-doped III-V DMS materials, interstitial Mn is far from being a well understood defect. The presence of Mn i in ferromagnetic (Ga,Mn)As was first reported based on ion channeling measurements. 6Although consistent with Mn i occupying tetrahedral (T) interstitial sites, the measurements did not allow to discriminate between the two nonequivalent T sites: coordinated by four Ga atoms (T Ga ) or by four As atoms (T As ). Transmission electron microscopy measurements using the (002) diffracted beam indicated that Mn i predominantly occupies the T As site.7 X-ray absorption fine structure (XAFS) techniques were later applied, suggesting T Ga occupancy (e.g., Refs. 8 and 9). However, XAFS is not well suited to distinguish neighboring elements with similar atomic numbers, as is the case for Ga and As, especially in such cases of multi-site occupancy (substitutional and interstitial), where the site to be identified is in fact the minority one (interstitial). In pi...

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Density of Mn interstitials in (Ga,Mn)As epitaxial layers determined by anomalous x-ray diffraction

Abstract: Articles you may be interested inEffect of low-temperature annealing on the electronic-and band-structures of (Ga,Mn)As epitaxial layers

Cited by 6 publications

References 17 publications

Diffusion of Mn interstitials in (Ga,Mn)As epitaxial layers

Diffusion of Mn interstitials in (Ga,Mn)As epitaxial layers

The use of anomalous x-ray diffraction as a tool for the analysis of compound semiconductors

Identification of the interstitial Mn site in ferromagnetic (Ga,Mn)As

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