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Microwave plasma assisted chemical vapor deposition was used to grow nanocrystalline diamond films.

The partial one-neutron removal cross section of 24O leading to the first excited state in 23O has been measured to be 65.7 ± 5.3 mb with a proton target in inverse kinematics at the beam energy of 62 MeV/nucleon. The decay energy spectrum of the neutron unbound state of 23O was reconstructed from the measured four momenta of 22O and the emitted neutron. A sharp peak was observed at Edecay = 48 ± 3 keV, confirming the previous measurements. The measured partial longitudinal momentum distribution of 23O* showed the d-wave knockout character, providing a support for the Jπ assignment of 5/2+ for this state. The spectroscopic factor for the neutrons in 0d5/2 orbital was deduced, for the first time, to be C2S(0d5/2) = 3.7 ± 0.3 (preliminary) by comparing with the result of Glauber model. The relatively large spectroscopic factor supports the N = 16 shell closure in the neutron drip-line nucleus 24O.

The first-principles calculations are employed to study the large anisotropy observed in the spin polarization in the cubic and tetragonal martensitic phases of the Heusler alloy [Ni.sub.2]MnGa. The maternistic transitions of the alloy are shown to highly affect the Fermi surface topology of the system.

Electron-cyclotron-wave-resonance plasma-assisted deposition was used to prepare nanocrystalline boron carbonitride. Results confirmed the presence of ternary sp(super 3)-bonded structure and a punctured lattice.

The preparation of highly transparent nanocrystalline diamond coatings on quartz glass substrates by the microwave plasma-enhanced chemical vapor deposition (MW-CVD) method, using the hydrogen-methane gas mixture, is presented. The deposits are compact, hard and highly transparent, and they are competitive for the applications as protective coatings for the optical components.

Abstract: We report for the first time the discrimination of the core fragment knockout and valence nucleon knockout reaction mechanisms at medium energy range, by the use of the recoil proton tagging technique. Intense 8He beams at 82.3 MeV/u were supplied by the RIPS beam line at RIKEN, and impinged on both hydrogen and carbon targets. Recoil protons were detected in coincidence with the forward moving core fragments and neutrons. The core fragment knockout mechanism is identified through the polar angle correlation and checked by various kinematics relations. This mechanism may be used to extract the cluster structure information of unstable nuclei. On the other hand, with the selection of the tagged valence nucleon knockout mechanism, a narrower peak of 7He ground state is obtained. The extracted neutron spectroscopic factor is relatively smaller than the no-tagged one, and is in good agreement with the prediction of ab initio Greenʼs function Monte Carlo calculations. [Copyright &y& Elsevier]

Confinement of silicon nanoparticles in silicon nitride instead of an oxide matrix might materially facilitate its potential applications as a light-emitting component in optoelectronics. We report in this letter the production of high-density (up to 4.0×10[sup 12]/cm[sup 2] from micrographs) silicon nanoparticles in SiN[sub x] thin films by chemical vapor deposition on cold substrates. Strong room-temperature photoluminescence was observed in the whole visible light range from the deposits that were postannealed at 500 °C for 2 min. The Si-in-SiN[sub x] films provide a significantly more effective photoluminescence than Si-in-SiO[sub x] fabricated with similar processing parameters: for blue light, the external quantum efficiency is over three times as large. The present results demonstrate that the nanostructured Si-in-SiN[sub x] system can be a very competitive candidate for the development of tunable high-efficiency light-emitting devices. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Spontaneous emergence of nanoscaled structures provides a potential alternative to the conventional bottom-up and top-down fabrication techniques. By a two-step thermal evaporation of mixed Ag2O and SiO2 powder onto sapphire substrate, concentric Ag/SiOx spherules were assembled into a triangular pattern upon cooling on the spherical surface of large particles, which, of generally a few microns in dimension, were primarily grown with the substrate held at 1270 K. The occasional presence of pentagon or heptagon defect, as required by the spherical geometry of the primary particle, was also recognized. Strain field in the oxide shell arising from expansion mismatch with the silver core seeds the subsequent nucleation events. The triangular pattern of the secondary nanoparticles can be accounted for with a minimized strain energy in the spherical surface. The self-assembled structure of striking uniformity is promising for the generation of a large family of building blocks for device production. [ABSTRACT FROM AUTHOR]

Abstract: Nanocrystalline Cu3NZn x compound films were synthesized using reactive magnetron sputtering of metal targets. Up to a Zn content of 5.44at.%, the deposits exhibit a satisfactory crystallinity that the X-ray diffraction patterns show distinct (001) and (002) reflections characteristic of the intrinsic Cu3N lattice. The slightly enlarged lattice constant suggests insertion of zinc atoms to the center of cells of primitive Cu3N lattice. All the ternary deposits exhibit an n-typed conductivity. Electrical resistivity at room temperature drops by three orders of magnitude with increasing zinc concentration from 0 to 5.44at.%, and accordingly the activation energy for electrical conduction decreases from 21.9 to 14.1meV, indicating the presence of shallow donor levels in doped samples. The electronic transport is governed by thermal activation in lightly doped samples, whereas in samples with a zinc concentration of 5.44at.% or higher it is instead dominated by a hopping mechanism at low temperatures (<50K). [Copyright &y& Elsevier]

Abstract: Photoluminescence from Er3+-implanted Si-in-SiN x films emitting efficiently visible light were investigated. A Stark structure in the Er3+ photoluminescence spectrum was observed at room temperature, which reveals more than one site symmetry for the Er3+-centers in the Si-in-SiN x matrix. The correlation between the visible photoluminescence from the silicon nanoparticles and the 1.54μm emission from the Er3+-centers was discussed. [Copyright &y& Elsevier]

Abstract: Copper nitride (Cu3N) is a thermally unstable material; therefore both the deposition of a stoichiometric sample and the reliable characterization of its properties constitute a big challenge. We reported here the growth of stoichiometric Cu3N films on Si (100) wafer by reactive magnetron sputtering of Cu target using pure nitrogen as working gas. At a low substrate temperature (60°C), a combination of high working pressure (>0.7Pa) and low RF power supply (<150W) favors the formation of stoichiometric deposits. With the pressure at 0.9Pa and the RF power below 100W, the deposits are [001]-oriented and consist of cubic Cu3N grains, which are typically 40nm in dimension. The lattice constant is 0.383nm as determined by both X-ray diffraction and transmission electron microscopy; and the electrical resistivity measurement reveals a typical deficit semiconductor behavior in the cubic Cu3N. The thermal decomposition temperature, being reported within 100–470°C, was determined to be ∼350°C as indicated by the presence of Cu (111) and (002) reflections after prolonged annealing. [Copyright &y& Elsevier]