The effect of a material growth technique on ion-implanted Mn diffusion in GaAs

We report on β − emission channeling experiments on the lattice location and thermal stability of Mn impurities (<0.05%) in both semi-insulating and heavily n-type doped GaAs. In addition to the majority of the Mn impurities substituting for Ga, up to 30% occupy tetrahedral interstitial sites with As nearest neighbors. Whereas the interstitial fraction is stable up to 400 • C, with an activation energy for diffusion of 1.7-2.3 eV, substitutional Mn diffuses only at ∼700 • C with an activation energy of ∼3 eV. By comparing these results to those of recent emission channeling experiments on heavily p-type doped GaAs [L. M. C. Pereira et al., Appl. Phys. Lett. 98, 201905 (2011)], we conclude that the observed high thermal stability of the interstitial fraction cannot be ascribed to trapping by charged defects, but is an intrinsic characteristic of isolated interstitial Mn in the low doping regime (<0.05% Mn). Compared to ferromagnetic Ga 1−x Mn x As (few percent Mn), for which a significantly lower activation energy has been reported, these findings motivate a comprehensive assessment of how the thermal stability and the diffusion of interstitial Mn are affected by the Mn concentration.

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“…Fig. 4), which is in agreement with a recent radio-tracer study on the diffusion of Mn in GaAs, 30 yielding an activation energy of ∼3 eV.…”

Section: Substitutional Mnsupporting

confidence: 91%

“…The estimated activation energy is therefore the same as for the scenario of long-range diffusion without precipitation (E a = 2.9 eV), and consistent with the radio-tracer measurements mentioned above. 30 …”

Section: Substitutional Mnmentioning

confidence: 99%

Stability and diffusion of interstitial and substitutional Mn in GaAs of different doping types

et al. 2012

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“…In fact, the fast component in Ref. 11 (with E a ≈ 3 eV) more likely corresponds to Frank-Turnbull diffusion of the substitutional Mn fraction via interstitial sites, since E a is well above the maximum estimated here for the direct interstitial diffusion of the interstitial Mn fraction (2.3 eV).…”

mentioning

confidence: 62%

Direct identification of interstitial Mn in heavily p-type doped GaAs and evidence of its high thermal stability

Pereira¹,

Wahl²,

Decoster³

et al. 2011

Applied Physics Letters

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We report on the lattice location of Mn in heavily p-type doped GaAs by means of β− emission channeling from the decay of M56n. The majority of the Mn atoms substitute for Ga and up to 31% occupy the tetrahedral interstitial site with As nearest neighbors. Contrary to the general belief, we find that interstitial Mn is immobile up to 400 °C, with an activation energy for diffusion of 1.7–2.3 eV. Such high thermal stability of interstitial Mn has significant implications on the strategies and prospects for achieving room temperature ferromagnetism in Ga1−xMnxAs.

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“…In order to perform experiments with short-lived isotopes, sophisticated on-line radiotracer setups have been constructed, which allow to carry out all steps in a minimum of time. During recent years the tracer diffusion studies have investigated transition metal diffusion in CdTe [41][42][43][44] and diffusion of Be, Ga, and Sn in Ge and SiGe alloys [45][46][47][48], of Be in glassy carbon [49] and of Mn in GaAs [50]. Figure 4 shows concentration profiles of the radiotracers 111 Ag, 67 Cu,193 Au, and 24 Na measured in CdTe crystals after implantation and subsequent diffusion under external Cd pressure [41][42][43][44].…”

Section: Tracer Diffusionmentioning

confidence: 99%

Materials science and biophysics applications at the ISOLDE radioactive ion beam facility

Wahl

2011

Nuclear Instruments and Methods in Physics Research Section B:

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The ISOLDE isotope separator facility at CERN provides a variety of radioactive ion beams, currently more than 800 different isotopes from ~65 chemical elements. The radioisotopes are produced on-line by nuclear reactions from a 1.4 GeV proton beam with various types of targets, outdiffusion of the reaction products and, if possible, chemically selective ionisation, followed by 60 kV acceleration and mass separation. While ISOLDE is mainly used for nuclear and atomic physics studies, applications in materials science and biophysics account for a significant part (currently ~15%) of the delivered beam time, requested by 18 different experiments. The ISOLDE materials science and biophysics community currently consists of ~80 scientists from more than 40 participating institutes and 21 countries. In the field of materials science, investigations focus on the study of semiconductors and oxides, with the recent additions of nanoparticles and metals, while the biophysics studies address the toxicity of metal ions in biological systems. The characterisation methods used are typical radioactive probe techniques such as Mössbauer spectroscopy, perturbed angular correlation, emission channeling, and tracer diffusion studies. In addition to these "classic" methods of nuclear solid state physics, also standard semiconductor analysis techniques such as photoluminescence or deep level transient spectroscopy profit from the application of radioactive isotopes, which helps them to overcome their chemical "blindness" since the nuclear half life of radioisotopes provides a signal that changes in time with characteristic exponential decay or saturation curves. In this presentation an overview will be given on the recent research activities in materials science and biophysics at ISOLDE, presenting some of the highlights during the last five years, together with a short outlook on the new developments under way.

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The effect of a material growth technique on ion-implanted Mn diffusion in GaAs

Cited by 7 publications

References 27 publications

Stability and diffusion of interstitial and substitutional Mn in GaAs of different doping types

Stability and diffusion of interstitial and substitutional Mn in GaAs of different doping types

Direct identification of interstitial Mn in heavily p-type doped GaAs and evidence of its high thermal stability

Materials science and biophysics applications at the ISOLDE radioactive ion beam facility

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