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Abstract: Iron, fluorine and boron ions were implanted into highly oriented pyrolytic graphite (HOPG). The samples were characterized before and after ion implantation as well as after heat treatments in vacuum by measurements of the magnetic moment and element analysis. Whereas the main magnetic contribution remains diamagnetic the paramagnetic one clearly increases with implantations and correlates with the amount of implanted ions. It is shown that a large part of the paramagnetic contribution is caused by the structural disorder created by particle bombardment using iron, fluorine or boron. All implanted HOPG samples show practically no change of the small ferromagnetic signal observed in their virgin state. No particular influence of iron on the ferromagnetic properties of HOPG is observed, up to ∼4000μg/g Fe-concentration in the implanted region. For comparison, ferrous sulphates were added to ultra-clean graphite powder. This iron addition increases the number of paramagnetic spins proportional to the iron content in the untreated samples. In heat-treated samples however, a clear ferromagnetic behaviour is observed due to the formation of a ferromagnetic iron compound. [Copyright &y& Elsevier]

Abstract: The combination of microbeam implantation and in-situ micro RBS/channeling analysis in the Rossendorf nuclear microprobe facility enables crystal damage studies with high current densities not achievable in standard ion implantation experiments. Si(100) samples were implanted with 600keV Si+ ions and a fluence of 1×1016 cm−2. Using a beam spot of 200μm×200μm current densities from 4 to 120μA/cm2 were obtained. The substrate temperature was varied between RT and 265°C. The implanted regions were subsequently analysed by micro RBS/channeling with a 3MeV He+ beam having a spot size of 50μm×50μm. Crystal damage up to amorphisation was observed in dependence on the substrate temperature. Above a critical temperature T C no amorphisation occurs. T C was determined for each series of samples implanted with the same ion current density j. It was found that the empirical Arrhenius relation j ∼exp(−E a/kT C), known from standard implantation experiments, is also valid at high current densities. The observed Arrhenius law can be derived from a model of epitaxial crystallisation stimulated by defect diffusion. [Copyright &y& Elsevier]

Presents information on a study that performed the analysis of silicon carbide films obtained by carbon ion implantation into amorphous by infrared and Raman scattering spectroscopies, transmission electron microscopy. Experimental procedure; Results and discussion on the study.

Nanometer-sized SiC precipitates were synthesized at 450 °C in Si by simultaneous dual beam implantation of C+ and Si+ ions and subsequent annealing. The results are compared with those of sequential dual beam implantation and of single beam implantation. Two types of SiC precipitates were found. Precipitates of type I with a diameter of d=4–5 nm consist of 3C-SiC epitaxially oriented with the Si matrix. They were formed already in the as-implanted state and do not grow further during subsequent annealing. The SiC precipitates of type II with d≈10 nm are not oriented with the Si matrix and grow exclusively during the subsequent annealing. The high growth velocity, the misorientation in regard to the Si matrix and the lower concentration of type II precipitates can be explained by the assumption that these precipitates were formed in an amorphous substrate which modifies their interface energy. [Copyright &y& Elsevier]

6H-SiC samples were amorphised by multiple Al implantations at room temperature, in order to study the annealing process. The paper deals with the influence of specific annealing conditions, such as furnace atmosphere and heating rate, on SiC reordering and Al profile. Below a certain deposited nuclear energy, solid phase epitaxy is possible and leads to recrystallisation under precise conditions (high heating rate, silicon partial pressure prescribed). Above it, material etching and dopant losses are observed, even though annealing has proven to be efficient for avoiding surface impairment (due to a specific cleaning process). [Copyright &y& Elsevier]

We investigated how to control the growth of vertically aligned graphene on C-face SiC by varying the processing conditions. It is found that, the growth rate scales with the annealing temperature and the graphene height is proportional to the annealing time. Temperature gradient and crystalline quality of the SiC substrates influence their vaporization. The partial vapor pressure is crucial as it can interfere with further vaporization. A growth mechanism is proposed in terms of physical vapor transport. The monolayer character of vertically aligned graphene is verified by Raman and X-ray absorption spectroscopy. With the processed samples, d 0 magnetism is realized and negative magnetoresistance is observed after Cu implantation. We also prove that multiple carriers exist in vertically aligned graphene.