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In this paper, junctions with reduced [H.sub.f] coupling were fabricated by ion beam deposition and oxidation, using CoFeB electrodes. The CoFeB layer has a strong (111) texture that can be the origin of lower [H.sub.f] and coercivity when compared with CoFe. Junctions processed down to 2 x 4/[micro][m.sup.2] with 40-[Angstrom]-thick CoFeB bottom eiectrodes have 42% of tunneling magnetoresistance (TMR), (R x A ~ 400 [OMEGA]x[micro][m.sup.2]), [H.sub.c] of ~10 Oe and [H.sub.f] of ~2 Oe. CoFe-based junctions (R x A ~ 500 [OMEGA]x[micro][m.sup.2]) have lower TMR (~35%) and larger [H.sub.f] (~5-6 Oe) and [H.sub.c] (~12-14 Oe). Local chemical composition analysis of the cross section indicated Fe-O segregation with very little Co grown on top of the barrier for CoFe-based junctions and not for CoFeB ones. Index Terms--CoFeB electrodes, ion beam deposition, low ferromagnetic coupling, tunnel junctions.

Boron suboxide BO[sub x] thin films have been deposited on Si (100) by reactive rf magnetron sputtering of B powders in an Ar/O[sub 2] atmosphere. Elastic recoil detection analysis and x-ray diffraction were used to study the influence of the O incorporation on the film composition and structure and relate them to mechanical properties, which were evaluated by nanoindentation. As x in BOx was increased from 0.08 to 0.18, the elastic modulus of the x-ray amorphous films decreased from 273 to 231 GPa, by 15%. This can be understood using classical molecular dynamics (MD) with a Buckingham-like interaction potential: The increase in the O concentration and corresponding formation of B-O bonds, shown to be longer than the B-B bonds, resulted in larger ionic contributions as well as a density reduction. This increased ionicity was responsible for the observed decrease in elastic modulus. As even more O was incorporated (x > 0.18), the H concentration increased, exceeding 0.3 at. %. This may cause the formation of boric acid (H[sub 3]BO[sub 3]) as a result of the chemical reaction with H[sub 2]O upon atmosphere exposure. The presence of van der Waals and hydrogen bonding, associated with H[sub 3]BO[sub 3] formation, provides a reasonable explanation for the extensive decrease in elastic modulus from 231 to 15 GPa, by 94%. The parameterization for the Buckingham-like interaction potential, introduced in this study, can be used for MD simulations of amorphous BOx systems without H[sub 3]BO[sub 3]. [ABSTRACT FROM AUTHOR]

Abstract: BC x N y thin films deposited at 250°C by pulsed reactive magnetron sputtering of a B4C target in an Ar/N2 plasma were studied by elastic recoil detection analysis, Fourier transform infrared, Raman, and photoelectron spectroscopy, electron microscopy, and nanoindentation. In the concentration range of 6% to 100% N2 in the sputter plasma the segregation into nanocrystalline hexagonal boron nitride and amorphous sp2 carbon is the dominant process during the film growth. The stoichiometric ratio and structural details of the major phases depend on the N2 concentration in the plasma and have significant influence on the Young′s modulus and the elastic recovery of the BC x N y thin films. [Copyright &y& Elsevier]

Abstract: This paper deals with a detailed study of changes that lithium tantalate (LT) and lithium niobate (LN) single crystals undergo during the annealed proton exchange (APE) process of optical waveguides’ formation. It is a well-known fact that several cases of anomalous behaviour are connected to the APE:LT samples, bringing thus an obstruction for the practical utilization of the APE:LT waveguides. As the LT crystal possesses even better optical properties than the LN crystal (e.g., it is less susceptible to optical damage), it is desirable to provide research focused on its behaviour during the APE process in order to acquire a control over the fabrication of the APE:LT devices. Neutron depth profiling (NDP), elastic recoil detection analysis (ERDA) and heavy ion ERDA (HI-ERDA) were performed to study changes in the surface of the LT and LN Z-cut wafers caused by the APE treatment and to determine the concentration depth profiles of the exchanged ions (lithium and hydrogen). Information on modifications of the crystals during the APE was obtained using X-ray diffraction (XRD) analysis. Optical/waveguiding properties of the samples were obtained by means of the standard mode spectroscopy at 633nm. The experiments proved that the LT is significantly less affected by the APE process compared to the LN and that most characteristics of the APE:LT layers can be easily restored towards that of the virgin crystal by the annealing process. [Copyright &y& Elsevier]

Cr/Sc multilayer mirrors, synthesized by ion-assisted magnetron sputter deposition, are proved to have a high near-normal reflectivity of R = 14.5% at a grazing angle of 87.5 degrees measured at the wavelength lambda = 3.11 nm, which is an improvement of more than 31% compared with previously published results. Elastic recoil detection analyses show that the mirrors contained as much as 15 at. % of N and traces of C and O. Soft x-ray reflectivity simulations reveal interface widths of sigma = 0.34 nm and an exceptionally small layer thickness drift of approximately 1.6 x 10(-5) nm/multilayer period throughout the stack. Simulations show that a reflectivity of R = 25.6% is attainable if impurities and layer thickness drift can be eliminated. The abrupt interfaces are achieved with ion assistance with a low ion energy of 24 eV and high ion-to-metal flux ratios of 7.1 and 23.1 during Cr and Sc sputter deposition, respectively. In addition, a near-normal incidence reflectivity of 5.5% for the C VI emission line (lambda = 3.374 nm) from a laser plasma source was verified.