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Cluster deposited Pd films exhibit ferromagnetism in the temperature range from 1.8 to 400 K. The magnetization properties are found to be dependent on the film thickness. The varying morphology of the resulting Pd film with respect to thickness suggests that cluster size, deposition energy, and substrate type are crucial for the resulting film magnetization. This is demonstrated by the characteristic ferromagnetic hysteresis with the temperature dependent saturation magnetization, remanence, and coercivity of palladium nanocluster aggregates. The temperature dependence of the saturation magnetization, remanence, and coercivity of Pd nanoclusters were measured using an ultra-high-sensitive magnetometer based on a superconducting quantum interference device, and the morphology of the samples was analyzed by tunneling electron microscopy. [ABSTRACT FROM AUTHOR]

Czochralski- and float-zone- grown silicon detectors were irradiated with 2 to 5 MeV protons. Capacitance-voltage (CV) measurements served to deduce the effective doping profiles and current-voltage (IV) measurements served to obtaining information on irradiation-induced deep levels. The CV measurements show that the proton-induced net space charge is positive or negative depending on the energy of the bombarding ion. The commonly employed nonionizing energy loss hypothesis was tested with the low energy proton regime and prominent previously unobserved deviations from predictions were noted. [ABSTRACT FROM AUTHOR]

Silicon particle detectors made on Czochralski and float zone silicon materials were irradiated with 7 and 9 MeV protons at a temperature of 220 K. During the irradiations, the detectors were biased up to their operating voltage. Specific values for the fluence and flux of the irradiation were found to cause a sudden breakdown in the detectors. We studied the limits of the fluence and the flux in the breakdown as well as the behavior of the detector response function under high flux irradiations. The breakdown was shown to be an edge effect. Additionally, the buildup of an oxide charge is suggested to lead to an increased localized electric field, which in turn triggers a charge carrier multiplication. Furthermore, we studied the influences of the type of silicon material and the configuration of the detector guard rings. [ABSTRACT FROM AUTHOR]

After irradiation with 7 and 9 MeV protons, activation-induced effects were encountered in measurements of current-voltage (IV) and capacitance-voltage (CV) characteristics for Czochralski and float-zone grown silicon particle detectors prepared on printed circuit boards with copper electrodes. With the present detector construction, the 30Si(p,n)30P and 63Cu(p,n)63Zn reactions induce dominant interference in such measurements. The daughter nuclides are positron emitters with half-lives of 2.5 and 38.5 min, respectively, and the slowing down of the emitted positrons generates a significantly large concentration of electron-hole pairs in the detector volume increasing the leakage current level and decreasing the breakdown voltage. The observed time-dependent characteristics were verified by modeling the activation of the detector structure and the resulting leakage current. As a result, the electrical measurements cannot be performed immediately after irradiation due to silicon activation, and, generally, materials becoming easily activated should be avoided in the detector concept. [ABSTRACT FROM AUTHOR]

Diffusion of implanted 7Be in Si1-xGex (x=0.20,0.65,1.00) systems has been studied under intrinsic conditions in the temperature range of 460–720 °C by the modified radiotracer technique. Arrhenius-type behavior with activation enthalpies of 2.0 eV for Ge and 2.5 eV for the Si–Ge alloys was noted. Unexpectedly, the diffusivity of beryllium is higher in the Si0.80Ge0.20 material than in Si0.35Ge0.65 which is discussed in terms of possible prevailing diffusion mechanisms. It is proposed that Be diffusion in Si1-xGex systems is dissociative mechanism dominated for germanium rich materials and the kick-out (or interstitialcy) mechanism dominates in silicon rich materials. [ABSTRACT FROM AUTHOR]

The stopping powers of polycarbonate for protons of energy 0.6-5.9 MeV and α particles of energy 2.0-24.0 MeV have been measured in a transmission experiment employing thin-foil targets. The essence of the novel experimental method employed in the present measurements is to record both projectile energy and time of flight while constantly alternating measurements with and without the target foil in place. The accuracies of the proton data and α-particle data range from 2.0% to 3.0% and 2.2% to 2.7%, respectively. All of the resulting measurements were analyzed in terms of modified Bethe-Bloch theory in order to extract values of the target mean excitation energy (I) and Barkas-effect parameter (b). The composite results for the two projectiles are that I = 71.52 eV and b = 1.13, the former value lying about one standard deviation below the additivity value and the latter value lying about one standard deviation below the expected value of 1.4 ± 0.1. Previous measurements of the stopping power of polycarbonate for [sup 7]Li ions were analyzed by the same method, but with the inclusion of an effective charge parameter (δ). The proton and α-particle data, with a few lower-energy points included, were analyzed for a three-parameter fit, also. Results for the three projectiles studied indicate both internal consistency and agreement with expectations based on modified Bethe-Bloch theory. [ABSTRACT FROM AUTHOR]

Investigates the elastic scattering of [sup12]carbon, [sup14]nitrogen, [sup16]oxygen ions by sulfur near the non-Rutherford energy threshold below 21 megaelectronvolts. Analysis of the decreasing elastic scattering cross sections with increasing angle above a threshold energy and smooth oscillations; Function of high-enery heavy-ion beams in Rutherford backscattering spectrometry; Factors considered to predict the non-Rutherford energy threshold.

Presents a study which investigated the elastic scattering cross sections for [sup12]C, [sup14]N and [sup32]S ion bombardment below 70 megaelectronvolt at various recoil angles. Review of related literature; Brief background on elastic recoil detection spectrometry; Description of the experimental setup; Results and discussion.

Focuses on the measurement of the cross section for elastic scattering of protons through the use of natural copper (Cu), molybdenum (Mo), silver (Ag) and tin (Sn) near the Coulomb barrier. Determination of the threshold energies; Identification of those threshold energies ascertained; Experimental cross section ratios given for the elements of Cu, Mo, Ag and Sn; Information on the film thicknesses.

Studies defect formation and annealing behavior of InP implanted by low-energy 15N ions. Results of the implantation of ions into III-V compound semiconductors; Explanation of the experiment used in this study; Results of the experiment.

Studies the elastic scattering cross sections for proton scattering from 4He determined in the proton energy region of 1.4-6.0 MeV. Laboratory angles for proton energies; 4He ion bombardment for helium energies of 5.6-24 MeV; Comparison of cross section data with literature values; Normalized signal peak area.

Focuses on a study which determined the polyimide stopping powers for hydrogen and helium ions in an energy range of interest for ion beam applications. Discussion on the widespread use of polyimide in ion beam applications; Methodology of the study; Results and discussion.

Diffusion of Ga in relaxed intrinsic Si1-xGex layers has been determined at 907 °C within the whole composition range. Based on current results and available systematic diffusion data for Si, Ge, and Si1-xGex alloys, it is suggested that Ga diffusion is interstitialcy mediated in Si rich materials and vacancy mediated in Ge rich materials. The results indicate that the dominating diffusion mechanism change takes place at x∼0.6. [ABSTRACT FROM AUTHOR]

Reliable and accurate knowledge of the physical properties of elementary point defects is crucial for predictive modeling of the evolution of radiation damage in materials employed in harsh conditions. We have applied positron annihilation spectroscopy to directly detect mono-vacancy defects created in tungsten through particle irradiation at cryogenic temperatures, as well as their recovery kinetics. We find that efficient self-healing of the primary damage takes place through Frenkel pair recombination already at 35 K, in line with an upper bound of 0.1 eV for the migration barrier of self-interstitials. Further self-interstitial migration is observed above 50 K with activation energies in the range of 0.12–0.42 eV through the release of the self-interstitial atoms from impurities and structural defects and following recombination with mono-vacancies. Mono-vacancy migration is activated at around 550 K with a migration barrier of E m V = 1.85 ± 0.05 eV. [ABSTRACT FROM AUTHOR]

At present, ion implantation into metallic systems is given increasing attention, aiming at achieving properties and functionalities of technologically valuable materials not easily available via conventional techniques. In our experiments thin Al films were implanted with Fe ions in order to find out how the superconductive properties of the metal can be modified at will. The purpose was twofold, viz., first, to study the basic physics of superconductivity in low-dimensional metallic structures doped with impurities. The second purpose was to apply ion implantation for the suppression of undesired superconductivity in aluminum widely used for fabrication of micro- and nanodevices operated at low temperatures. In many applications transition to the superconductive state is detrimental for the device’s functionality, for instance, those based on Coulomb blockage (CB) effect (e.g., in CB thermometry). [ABSTRACT FROM AUTHOR]

A high crystalline quality Si[sub 0.75]Ge[sub 0.25] alloy layer grown by chemical vapor deposition was implanted with 70 keV Er[sup +] ions to a fluence of 10[sup 15] cm[sup -2] at temperature of 550 °C. The implantation was found to result in an Er depth distribution with 1 at. % maximum concentration 30 nm beneath the surface. The location of the erbium atoms in the host matrix lattice is derived through computer simulation of experimental axial channeling angular scans measured by in situ Rutherford backscattering/channeling spectrometry. Using computer code FLUX 7.7 it is shown that 60% of the implanted erbium atoms are located at ytterbium sites, 10% at tetrahedral sites, and the remainder are associated with random locations in the host matrix. [ABSTRACT FROM AUTHOR]

Elastic scattering of 12C, 14N, and 16O ions by aluminum, silicon, and titanium has been investigated below 34 MeV at a backscattering angle of 170°. The excitation functions at energies near the Coulomb barrier and non-Rutherford threshold energies above which the Rutherford cross sections become invalid, are presented for direct scattering and the kinematically reversed reactions. Sharply decreasing cross sections above the threshold energies, but no broad resonance-like structures, were observed. The non-Rutherford threshold energies are clearly higher than the values predicted by a theoretical model based on nuclear perturbation and optical model calculations recently presented in the literature. A new unpublished version of the model gives better agreement. [ABSTRACT FROM AUTHOR]

Presents a study which determined the effect of the hydrogen (H) implantation-induced defects on the H migration in n-type gallium arsenide. Determination of the depth scale; Effects of the deposited energy on the H migration; Indication of the dependence of the H solubilities on the annealing temperature.

A correction is presented to the research "Growth mode-dependent ferromagnetic properties of palladium nanoclusters" that was published in a 2018 issue.

A hybrid Coulomb blockade thermometer (CBT) in form of an array of intermittent aluminum and silicon islands connected in series via tunnel junctions was fabricated on a thin silicon-on-insulator (SOI) film. Tunnel barriers in the micrometer size junctions were formed by metal-semiconductor Schottky contacts between aluminium electrodes and heavily doped silicon. Differential conductance through the array vs. bias voltage was found to exhibit characteristic features of competing thermal and charging effects enabling absolute temperature measurements over the range of ~65 to ~500mK. The CBT performance implying the primary nature of the thermometer demonstrated for rather trivial architecture attempted in this work paves a route for introduction of Coulomb blockade thermometry into well-developed contemporary SOI technology. [ABSTRACT FROM AUTHOR]

Examines the diffusion of aluminum in polycrystalline ion-implanted α-titanium in the temperature range 600-850 degree celsius using ion-beam techniques. Method used in monitoring the time-dependent concentration profiles; Effect of the implantation energy and implanted dose on the diffusivity of aluminum; Process used to investigate the possible effect of radiation damage to the migration of the diffusing aluminum.

The magnetic response of two-dimensional uncapped Au islands tens of nanometers in size was measured using a superconducting quantum interference device magnetometer. The magnetization vs. field was found to exhibit a clear ferromagnetic-like hysteresis loop and a large positive remanent magnetization was acquired after momentary application of a strong magnetic field. The Au magnetic response is assumed to be due to the surface effects in the nanosized islands and the large fraction of canted surface magnetic moments which interaction and mutual orientation differ from the bulk diamagnetic order. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Nanoindention hardness anisotropy of alumina crystal: a molecular-dynamics study," by Nishimura and colleagues in the 2009 issue.

Cobalt silicide is a popular compound in semiconductor technology for fabricating resistive microcomponents and metallization. In advanced silicon-based cryogenic devices, such as radiation detectors and coolers, the electronic energy distribution is fundamentally determined by the thermal state of the mesoscopic system. In this work, electron-phonon heat transport at cryogenic temperatures was studied in a silicide formed by high fluence ion implantation of Co into Si. A heat flow between electrons and phonons was found to be proportional to (Telp-Tphp) with p=3.3. The electron-phonon coupling constant that characterizes the thermal resistance between electrons and phonons was derived from the power dependence of the electron temperature measured well bellow 1 K. The constant was found to be temperature dependent in the implanted cobalt silicide. [ABSTRACT FROM AUTHOR]

The charge state of mobile vacancy-impurity complexes in germanium was studied via the effect of p-type (Ga) doping on Ga and Sn diffusions. Tin diffusion retards significantly as a function of doping concentration suggesting diffusion dominated by negatively charged vacancy-Sn complexes. Gallium diffusion is practically unaffected by doping, suggesting diffusion dominated by vacancy-Ga complexes having the same charge state as isolated, negatively charged Ga ions. The evident two orders of magnitude higher diffusivity of group V elements in germanium than of group III and IV elements can be well explicated by means of the present findings. [ABSTRACT FROM AUTHOR]

Diffusion of Sn in relaxed Si1-xGex alloys has been studied systematically. In Si1-xGex, diffusion of Sn is faster than that of Si and Ge, and the results indicate that Sn diffusion in silicon and germanium is vacancy mediated. As Sn is isovalent, no long range Coulomb interactions exist between Sn atoms and native point defects. Since Sn atoms are larger than Si and Ge atoms, they cause stress in the SiGe lattice. The present findings are explained by attractive elastic interactions caused by pairing of Sn atoms with vacancies relaxing the stress and repulsive elastic interactions between Sn atoms and self-interstitials. [ABSTRACT FROM AUTHOR]

The time evolution of the silicon concentration profiles in ion-implanted polycrystalline α-Ti has been studied in the temperature range 650–800 °C. Diffusion couples were created by ion implantation. The time-dependent concentration profiles were monitored by the use of the nuclear resonance broadening technique through the 30Si(p,γ)31P reaction. The values of 1.09±0.18 eV for the activation energy and (4.4±404.0)×10-7 cm2/s for the frequency factor were obtained. The solubilities of Si in Ti are reported. The present result is discussed in the framework of the Ti silicide formation. [ABSTRACT FROM AUTHOR]