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Using radioactive isotopes produced at the CERN-ISOLDE facility, the lattice location of the implanted transition metal (TM) ions 56Mn, 59Fe and 65Ni in n-type single-crystalline hexagonal 6H-SiC was studied by means of the emission channeling technique. TM probes on carbon coordinated tetrahedral interstitial sites (TC) and on substitutional silicon sites (SSi,h+k) were identified. We tested for but found no indication that the TM distribution on SSi sites deviates from the statistical mixture of 1/3 hexagonal and 2/3 cubic sites present in the 6H crystal. The TM atoms partially disappear from TC positions during annealing at temperatures between 500 °C and 700 °C which is accompanied by an increase on SSi and random sites. From the temperature associated with these site changes, interstitial migration energies of 1.7–2.7 eV for Mn and Ni, and 2.3–3.2 eV for Fe were estimated. TM lattice locations are compared to previous results obtained in 3C-SiC using the same technique. [ABSTRACT FROM AUTHOR]

We have investigated the lattice location of implanted transition metal (TM) 56Mn, 59Fe and 65Ni ions in undoped single-crystalline cubic 3C–SiC by means of the emission channeling technique using radioactive isotopes produced at the CERN-ISOLDE facility. We find that in the room temperature as-implanted state, most Mn, Fe and Ni atoms occupy carbon-coordinated tetrahedral interstitial sites (TC). Smaller TM fractions were also found on Si substitutional (SSi) sites. The TM atoms partially disappear from ideal-TC positions during annealing at temperatures between 500 °C and 700 °C, which is accompanied by an increase in the TM fraction occupying both SSi sites and random sites. An explanation is given according to what is known about the annealing mechanisms of silicon vacancies in silicon carbide. The origin of the observed lattice sites and their changes with thermal annealing are discussed and compared to the case of Si, highlighting the feature that the interstitial migration of TMs in SiC is much slower than in Si. [ABSTRACT FROM AUTHOR]

The angular distribution of β− particles emitted by the radioactive isotope 24Na was monitored following implantation into ZnO single crystals at fluences above 5 × 1012 cm−2 at CERN’s ISOLDE facility. We identified sodium on two distinct sites: on substitutional Zn sites and on interstitial sites that are close to the so-called octahedral site. The interstitial Na was to a large extent already converted to substitutional Na for annealing at 200 °C, from which an activation energy of 0.8–1.3 eV, most likely around 1.2 eV, is estimated for the migration of interstitial Na in ZnO. [ABSTRACT FROM AUTHOR]

Strain is a critical parameter affecting the growth and the performance of many semiconductor systems but, at the same time, the accurate determination of strain profiles in heterostructures can be challenging, especially at the nanoscale. Ion channelling/blocking is a powerful technique for the detection of the strain state of thin films, normally carried out through angular scans with conventional particle detectors. Here we report the novel application of position sensitive detectors for the evaluation of the strain in a series of AlInN/GaN heterostructures with different compositions and thicknesses. The tetragonal strain is varied from compressive to tensile and analysed through bidimensional blocking patterns. The results demonstrate that strain can be correctly quantified when compared to Monte Carlo channelling simulations, which are essential because of the presence of ion steering effects at the interface between the layer and the substrate. Despite this physical limitation caused by ion steering, our results show that full bidimensional patterns can be applied to detect fingerprints and enhance the accuracy for most critical cases, in which the angular shift associated to the lattice distortion is below the critical angle for channelling. [ABSTRACT FROM AUTHOR]

We have investigated the lattice location of implanted in silicon. By means of emission channeling, three different lattice sites have been identified: ideal substitutional sites, displaced bond-centered sites and displaced tetrahedral interstitial sites. To assess the origin of the observed lattice sites we have compared our results to emission channeling studies on and and to Mössbauer spectroscopy experiments on , present in literature. The possible interpretation of several Mössbauer lines is discussed in the light of our new results on the lattice location. The conclusions are relevant for the microscopic understanding of some gettering techniques. [ABSTRACT FROM AUTHOR]