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The characterization of ferromagnet-semiconductor interfaces with monolayer (ML) depth resolution is an important issue in the development of spin injection devices. In this article, highly resolved depth distributions of Fe have been measured during the initial stages of growth of Fe on Si (100) at room temperature by in situ high-resolution Rutherford backscattering spectrometry. Extensive in-diffusion of Fe has been observed even for the coverage of 0.0325 ML of Fe. At this coverage the Si crystal structure is apparently still conserved. Every second Si layer is depleted of Fe, thus giving rise to compositional oscillations of Fe. At higher coverages strong interdiffusion occurs resulting in the formation of silicides at the interface. Even at 9.2 ML of Fe coverage, no pure Fe layers were observed.

Highly resolved Co depth profiles have been obtained during the initial stages of Co growth on Si(100) at low temperature (-60 °C) by in situ high-resolution Rutherford backscattering spectrometry. We found extensive Co in-diffusion in the submonolayer growth regime even at this low temperature, besides Co on top of the Si surface. The amount of diffused-in Co is larger than the amount of Co at the Si surface. Every second Si layer is depleted of Co, starting at the Si surface, thus giving rise to compositional oscillations of Co in the Si(100) lattice. At this low temperature the growth of metallic Co on the Si surface is observed at 0.1 ML of deposited Co, which continues for higher coverages. At much higher coverage (5.93 ML of Co) almost exclusively low Co content silicides are formed at the Co/Si interface. The data presented here are compared with previous room temperature deposition data and are different in several aspects.

Common failure mechanisms in microelectronics such as electromigration, creep and fatigue can be positively influenced by microstructure optimization. In this paper a new mechanism of microstructure optimization in thin metal films is proposed. Post-deposition ion bombardment can produce an in-plane texture in originally highly fiber textured thin metal films by a selective grain growth process. In extreme cases the in-plane texture becomes as sharp as the out-of-plane fiber texture. A subset of grains oriented for ion channeling was found to grow significantly at the expense of the remaining grain fraction. We studied the selective grain growth as a function of ion species (N+, Ne+, Ar+), ion energy (1–3.5 MeV) and target temperature (liquid nitrogen to 400 °C). In a textured thin film the degree of preferred in-plane orientation can be strongly influenced by ion bombardment, and therefore this technique has the potential to become a powerful tool for the enhancement of reliability in micro- and nanosystems.

We report measurements of electrical resistivity ( ρ ), Hall coefficient ( R H ) , magnetization ( M ) and specific heat ( C p ( T ) ) of high-quality icosahedral Al 70.4 Pd 20.8 Mn 8.8 phases with different thermal treatment. An improvement in the quasi-crystallinity upon the annealing treatment caused a drastic increase in ρ up to 7000 μΩ cm accompanied by a very small electronic specific heat coefficient γ . The low temperature ρ ( T ) data has been analyzed in terms of weak localization and electron–electron interaction effects. The Hall resistivity ( ρ H ) is found to be strongly temperature-dependent and varies linearly with the magnetization ( M ) for the same field and temperature. Magnetization measurement reveals that more conductive samples are more magnetic and vice versa. Magnetic susceptibility ( χ ) data of all the annealed samples agrees with the Curie–Weiss-like behavior implying the existence of localized moments. The negative Curie–Weiss temperature ( θ ) indicates strong antiferromagnetic coupling between individual Mn atoms. The magnetic Mn concentration is found to be small, ranging from 1.7 3 × 1 0 - 4 for the less magnetic sample studied up to 3 × 1 0 - 3 for the more magnetic one. The small electronic specific heat coefficient obtained for all the samples suggests a significant reduction in the electronic density of states (DOS) at the Fermi level ( E F ) upon thermal annealing treatment.

The paper is concerned with sintering of near-surface layers of ceramic materials by ion beam irradiation, a technique that has been developed in our institute in Stuttgart in recent years. When sintering ceramic powders, the problem of degradation of the ceramic materials themselves or the substrates they are deposited on before they start sintering is often encountered. One way of solving these problems is the use of ion beam irradiation. On irradiation, defects are introduced into the material, which initiates sintering, provided the defects are mobile at the temperature of the irradiation. In this way, the sintering temperature can be considerably reduced. The paper outlines the principles of conventional and radiation-induced sintering. Experiments are reported for MeV ion irradiation used to sinter SiC powder material. In a thin surface layer (a few μm), a dense structure is produced in the material at a temperature (low for SiC) of 1450 °C.

For studying the strain-softening phenomenon of icosahedral Al–Pd–Mn single quasicrystals, compression tests with constant plastic strain rate were performed in the strain regime following the upper yield stress and combined with stress-relaxation experiments and temperature changes along the stress–strain curves at selected strains. It is found that both the strain-rate sensitivity and the temperature sensitivity of the flow stress decrease in the above strain regime with increasing strain. These results favour a model which assumes strain softening being caused by a change of the configuration of large cluster-like obstacles (e.g., the icosahedral clusters present in i-Al–Pd–Mn quasicrystals) by the moving dislocations thus reducing the stress needed to maintain the deformation.

Channeling Monte Carlo simulations, in combination both with Rutherford backscattering (RBS) and particle-induced X-ray emission (PIXE), have been performed on model quasicrystals of decagonal Al–Cu–Co with different amount of phason disorder. Comparing our simulation results to experimental data we obtain the best agreement for those models with a large amount of phason disorder. This leads us to the conclusion that the sample of d-Al–Cu–Co used in the measurements is a random tiling. Besides the aspect of phason disorder we also examined the Cu and Co distribution given by the Burkov models (S.E. Burkov, Phys. Rev. B 47 (1993) 12325). We show that the chemical distribution is in contrast to the experimental PIXE yield profiles. By exchanging some of the Cu and Co positions it is possible to eliminate the discrepancy.

Icosahedral AlPdMn single quasicrystals were deformed in compression with constant plastic strain rate in order to study the strain-softening phenomenon which is observed in the strain regime following the upper yield stress and which characterizes the shape of the stress-strain curves of quasicrystals. Stress-relaxation experiments and temperature changes were performed along the stress-strain curves at selected strains. It is found that both the strain-rate sensitivity and the temperature sensitivity of the stress decrease in the above strain regime with increasing strain. Within the regime of constant stress following the strain softening regime at large strains both sensitivities remain constant. These results favour a model which assumes strain softening being caused by a change of the configuration of large cluster-like obstacles (e.g. the icosahedral clusters present in i-AlPdMn quasicrystals) by the moving dislocations thus reducing the stress needed to maintain the deformation.

In a model quasicrystal for decagonal AlCuCo the phason disorder was gradually increased and the channeling PIXE yields were computed for 3 MeV He ions by Monte Carlo simulations. For large phason disorder good agreement with experimental data was obtained. Thus we conclude that the sample of d-AlCuCo used in the measurements is a random tiling. One remaining discrepancy, namely that the PIXE yields of the simulations are approximately the same for Cu and Co, is eliminated by optimization of the Cu and Co positions.

The paper is concerned with the analysis of surfaces and near-surface layers with monolayer depth resolution by means of high resolution Rutherford backscattering (HRBS) and elastic recoil detection (HERDA) of ions with an energy of a few MeV, in combination with an electrostatic spectrometer. With this instrument, which has recently been set up at the 6 MV Pelletron accelerator of the Max-Planck-Institut fur Metallforschung in Stuttgart, depth resolutions of 0.1 nm are obtained in HRBS and 0.3 nm in HERDA experiments. This paper gives a short outline of the design and performance of the spectrometer followed by various examples of applications. These comprise examples showing the analyzing power of the instrument, the analysis of an X-ray mirror by HRBS, the study of the initial oxidation of surfaces of aluminum single crystals by HERDA and recent results concerning charge exchange in ion backscattering.

To study the deformation characteristics of icosahedral Al 70.4 Pd 20.8 Mn 8.8 single-quasicrystals flow-stress measurements by compression tests have been performed in the temperature range 990–1105 K. Each test was combined with a stress relaxation experiment to determine the strain-rate sensitivity of the flow stress. The activation enthalpies Δ H calculated from these data are: (i) considerably smaller than the data known until now from the literature and (ii) exhibit a step at about 1050 K indicating different mechanisms for dislocation motion in AlPdMn with Δ H ≅ 3.7 eV below and Δ H ≅ 5.5 eV above 1050 K. In both regimes Δ H increases proportional to T suggesting different pre-exponential factors if an Arrhenius behaviour is assumed for the strain rate. From the slopes of the Δ H-T curves values for Δ S can be deduced which amount to 13 k below and 27 k above 1055 K. The results are interpreted on the basis of present models of dislocation motion in quasicrystals.

In order to obtain high spin injection efficiency, a ferromagnet-semiconducor Schottky contact must be of high crystalline quality. This is particularly important in the case of ferromagnet-silicon interfaces, since these elements tend to mix and form silicides. In this study Co-Si (100) interfaces were prepared in three different ways: by evaporation at room temperature, low temperature (), and with Sb as surfactant, and their interface structures were analyzed by high-resolution RBS (HRBS). In all cases more or less strong in-diffusion of Co with subsequent silicide formation was observed. In order to prevent the mixing of Co and Si, ultra thin MgO tunnel barriers were introduced in-between them. In situ HRBS characterization confirms that the MgO films were very uniform and prevented the mixing of the Si substrate with deposited Co and Fe films effectively, even at .

To develop new high density magnetic storage media and magneto-electric devices the knowledge of structure of used materials is most important. Therefore an investigation of this structure proceeds with a magnetic transmission X-ray microscope. For this purpose a X-ray beam has to be conical diverted with a special mirror assembly called condenser inside ultra-high vacuum surrounded by a steel tube. The existing system, at the synchrotron Bessy II in Berlin, uses a magnetic clutch and a tooth belt to make the condenser rotate. This causes vibrations. The paper presents an innovative approach, developed for the Max-Planck-Institute for metals research, Stuttgart, to run the mirrors without the mentioned problem. The new system benefits tremendously from a direct synchronous drive with permanent magnetic excitation where the active rotor part is adapted to the mirror construction and the stator is mounted on the outer side of the vacuum tube

We present a transmission electron microscopy (TEM)/Rutherford backscattering spectrometry (RBS)/x-ray-diffraction (XRD) study of Au evaporated on crystalline organic thin films of diindenoperylene (DIP). Cross-sectional TEM shows that the preparation conditions of the Au film (evaporation rate and substrate temperature) strongly determine the interfacial morphology. In situ XRD during annealing reveals that the organic layer is thermally stable up to about 150 degreesC, a temperature sufficient for most electronic applications. The x-ray measurements show that the "as-grown" Au layer exhibits a large mosaicity of around 10degrees. Upon annealing above approximate to120 degreesC the Au film starts to reorder and shows sharp (111)-diffraction features. In addition, temperature dependent RBS measurements indicate that the Au/DIP interface is thermally essentially stable against diffusion of Au in the DIP layer up to approximate to100 degreesC on the time scale of hours, dependent on the Au thickness. (C) 2003 American Institute of Physics.

It is the aim of this chapter to outline the principles of ion chapter in quasicrystals and to give an overview of the potential applications of this technique. We will see that in quasicrystals there exist rows and planes of atoms which are the prerequisite for channeling in ordered structures. In contrast to periodic lattices in quasicrystals these rows and planes exhibit a wide distribution of densities. This causes problems, in part, but does not render channeling impossible.

Thin epitaxial films of TbBaCo2O6−δ cobaltites have been synthesized using pulsed laser deposition. It was found that the film properties are extremely sensitive to the oxygen pressure during deposition, temperature of the substrate, and the cooling rate. Growth parameters were optimized for δ≈0.5 films with ordered Tb and Ba ions, as well as oxygen vacancies. The properties of these c-axis oriented films are similar to bulk TbBaCo2O5.5: they show a metal-insulator phase transition at TMI≈350 K, ferromagnetic order below TC=285 K, and antiferromagnetism at T

The Co distribution in the initial stages of growth of Co on Si (100) at room temperature has been probed in situ by high-resolution Rutherford backscattering spectrometry. Even at very low coverage (0.08 ML) extensive Co in-diffusion is found. The in-diffused Co forms a pronounced subsurface maximum which shifts into the Si bulk with increasing coverage and persists up to a coverage of 1.19 ML. The Co concentration at the surface saturates at the value of 0.5 for 1.19 ML of Co. Evidence of Si out-diffusion is seen for 2 and 2.93 ML which results in the formation of a CoSi phase.

The paper is concerned with the investigation of the displacement field of D in Ta by means of 1 MeV 3He+-ion channeling in combination with Rutherford backscattering. When loaded with deuterium the Ta-crystals exhibit a narrowing of the obtained backscattering minima. For a (100) plane and a D-concentration of 28% D/Ta a decrease in the angular half width of about 10% is observed. By comparison with calculations a value of (9.5±0.9) pm is determined for the displacements of the first neighbour Ta-atoms.

In this study thin Co films were grown on Si (100): (1) with one monolayer of Sb as surfactant and (2) without any surfactant. The Co film, its interface with the Si substrate and the behavior of the Sb surfactant layer were investigated during the growth by high-resolution Rutherford backscattering. By the use of Sb, the evaporated cobalt grows in a layer-by-layer mode and the mixing of Co and Si at the interface is strongly reduced. During the evaporation of Co, Sb floats on the surface for all Co coverages with some incorporation in the grown Co film only for higher coverages. The improvement of the interface quality is also reflected in the magnetic properties of the Co film.

The channeling of 300 keV deuterons combined with the D(d, p)T reaction has been used to determine the positions of deuterium dissolved in niobium. The comparison of the experimental data with theoretical reaction yield calculations indicates that deuterium in niobium is located on tetrahedral lattice sites.