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The valence state and annealing reactions of Mn/Fe in single crystalline α-AlO have been determined following low fluence (<10 cm) 60 keV implantations of Mn (T = 1.5 min) and emission Mössbauer spectroscopy on the Fe daughter nuclei in the temperature range from 110-700 K. At 110 K, most probe atoms are found in the Fe state in amorphous surroundings due to the implantation damage. A fraction of the Fe is found in cubic environment, possibly nano-precipitates of η-AlO. This site is found to disappear from the spectra above 500 K. Annealing of the damage sites at increasing temperatures leads first to increased incorporation of the probe atoms as Fe on Al sites, and, above room temperature, also as Fe. The Fe sub-spectrum is masked by slow paramagnetic relaxations following a T dependence, as expected for a two-phonon Raman process. Our data is consistent with data from Co and Fe implantations, suggesting a general increase in the average Fe valence state with lower implantation dose and negligible annealing reactions at room temperature. [ABSTRACT FROM AUTHOR]

Ion implantation provides a precise method of incorporating dopant atoms in semiconductors, provided lattice damage due to the implantation process can be annealed and the dopant atoms located on regular lattice sites. We have undertaken Fe emission Mössbauer spectroscopy measurements on GaAs and GaP single crystals following implantation of radioactive Mn ions, to study the lattice sites of the implanted ions, the annealing of implantation induced damage and impurity-vacancy complexes formed. The Mössbauer spectra were analyzed with four spectral components: an asymmetric doublet (D1) attributed to Fe atoms in distorted environments due to implantation damage, two single lines, S1 assigned to Fe on substitutional Ga sites, and S2 to Fe on interstitial sites, and a low intensity symmetric doublet (D2) assigned to impurity-vacancy complexes. The variations in the extracted hyperfine parameters of D1 for both materials at high temperatures ( T > 400 K) suggests changes in the immediate environment of the Fe impurity atoms and different bonding mechanism to the Mössbauer probe atom. The results show that the annealing of the radiation induced damage is more prominent in GaAs compared to GaP. [ABSTRACT FROM AUTHOR]

We present a method to describe the temperature dependence of emission Mössbauer spectra showing slow spin-lattice relaxations of Fe in MgO single crystals, obtained after implantation of Mn at ISOLDE/CERN. The analysis is based on the Blume-Tjon model for the line-shape of relaxing paramagnetic sextets with the spin relaxation rate, τ as a parameter. The temperature dependent spin relaxation rate of Fe in MgO is found to increase to ~10 s at 647 K by assuming a relaxation rate of τ < 10 s at 77 K. The results are in accordance with those obtained by electron paramagnetic resonance spectroscopy demonstrating the possibility of retrieving spin-lattice relaxation rates of dilute Fe from emission Mössbauer spectroscopy of Mn/Fe-implanted oxides. [ABSTRACT FROM AUTHOR]

Abstract: 57Fe Mössbauer spectroscopy following ion implantation of radioactive 57Mn+ ( T 1/2=85.4s) has been applied to study the formation of Fe/Mn implantation-induced defects in ZnO at temperatures between 319 and 390K. The formation of ferric iron–vacancy complexes is found to depend strongly on the implanted dose and to be faster and more efficient at higher temperatures. The results at these temperatures suggest the mobility of the Zn vacancy, together with vacancy trapping at the substitutional Mn/Fe impurities are responsible for the formation of Fe–VZn complexes. [Copyright &y& Elsevier]