Abstract: The subject of the present investigation is the influence of annealing on the
microstructure of Co thin films. In particular, the evolution of the texture during annealing is studied and compared with that of Co/Cu multilayers of different individual layer thicknesses. 400nm thick Co films show a h.c.p. structure with a weak preference of the <001> texture component and a broad distribution of grain orientations. Annealing at about 350°C results in a strong increase of the h.c.p. <001> component, nearly complete disappearance of the statistical distribution and grain growth of a minor f.c.c. fraction in the films. In-situ XRD measurements on
single Co films during annealing confirm that the texture change is irreversible. Multilayer stacks of Co/Cu layers show various texture changes depending on the individual layer thickness (ranging between 100nm and 1nm). Generally, with decreasing individual layer thickness and increasing annealing temperature the f.c.c. content in the multilayers increases at the expense of the h.c.p. fraction.
Abstract: Thin nanocrystalline CdS and CdxZn1-xS films have been synthesized on InP(100), Si(100), GaAs (100), sapphire(100) and fused silica substrates at low pressure (5 × 10-2-2 × 10 -1Torr)and in the temperature range of 473-673 K by remote plasma enhanced chemical vapor deposition (RPECVD) using Cd(S2CN(C2H5)2)2·C12H8N2 and Cd/Zn(S2CN(C2H5)2)2·C10H8N2 as single-source precursors. The influence of deposition conditions and type of substrates on physical and chemical properties of these films has been studied by X-ray diffraction of synchrotron radiation, HREM, SEM, SAED, ellipsometry, IR- and Raman spectroscopies, and EDS.
Abstract: Copper layers were deposited from acidic electrolytes containing different amounts of
organic additives, designed for the formation of Cu-interconnect structures. Amorphous Ni-P substrates allow to study the unbiased growth of the electrodeposits. The crystallographic texture was investigated by the determination of X-ray diffraction (XRD) pole figures and the calculation of the orientation distribution functions. XRD results are discussed in relation to the morphologies of the electrodeposits as investigated with light optical microscopy and correlated with the process parameters during electrodeposition.
Abstract: The structural characteristics of Au-TiB 2/GaAs and Au-Mo-TiB2-AuGe/GaAs device structures after deposition and short-term thermal annealing (STTA) were investigated. The multilayer contacts with TiB2 anti-diffusion layer were magnetron sputtered on (001) GaAs substrates. The structures were STTA in a stream of hydrogen at temperatures of 400°C, 600°C, and 800°C during 60 seconds. The X-ray diffraction techniques and atomic force microscopy were used for investigation. At STTA a reduction of residual strain in multilayer metallic films, an increment of film grain size, a change of grains preferred orientation in the Au polycrystalline film and a transformation of surface morphology of the upper Au film were observed. These
processes do not have monotonic temperature dependence. For Au-TiB2/GaAs a minimum value of residual strains was observed at T=600°C while for Au-Mo-TiB2-AuGe/GaAs it was observed at T=400°C. The roughness of Au film monotonically increased at annealing of Au-TiB2/GaAs structure at T=400°C and T=600°C and corresponded to the initial value at T=800°C. A strong change of Au film roughness was observed at annealing of Au-Mo-TiB2-AuGe/GaAs structure at T=600°C. The XRD pattern from a Au-TiB2 metal film denoted a quasi-amorphous structure in the initial state and an increment of micrograins size at STTA. In the initial state the crystalline structure of Au film in Au-Mo-TiB2-AuGe/GaAs structure had some preferred orientation in the <111> direction, which was reduced after STTA at T=600°C. The polycrystalline structure of Au film was partially deteriorated after STTA at T=800°C as TiB2 layer was destroyed and lost its diffusion protecting properties.
Abstract: Nanomaterials are the building blocks of nanotechnology. Recently, nanotube materials have attracted considerable attention due to their unique physical and chemical properties. Here we discuss how nanotubes can be used as templates for preparation of a new family of materials, the nanoporous single crystals, and for the preparation of metal sulfide nanotube materials. Today, the characterization of these materials depends heavily on electron microscopy. However, as rational synthesis schemes are becoming available, more well-defined, homogeneous nanotube samples will be produced and the role of diffraction techniques may increase.
Abstract: Alkyl-perfluoroalkyl compounds are known to form a microphase-separated structure due to the thermodynamic immiscibility between the fluorinated and the protonated segments [1,2]. Many similarities between bulk and surface structures of such polymers were found in the past [2,3,4] which can be explained by both microphase separation in the bulk as well as surface segregation of the fluorinated parts. Basing on this concept, polymers with chemically different main chains were attached with alkylperfluoroalkyl side chains (particularly, oxydecylperfluorodecyl chains, -O-(CH2) 10-(CF 2) 9-CF 3). Combined investigations by means of
temperature-dependent X-ray scattering, molecular modeling and DSC measurements were performed to characterize the bulk structure in dependence on the flexibility of the main chain as well as the density of side chains. The polymers under investigation show one or more phase transitions in the temperature range from room temperature to 300 °C which can be assigned as transitions between different smectic structures. These phases are characterized to have positive as
well as negative expansion coefficients, respectively, indicating changes of the tilt angle of the side chains and/or the degree of interdigitation. The polymer melts feature a high memory behavior evidenced by reversed imaging of the scattering patterns in the heating and cooling runs.
Abstract: The glass transition and the phase formation during crystallization of the
Zr52Ti5Cu18Ni15Al10 bulk metallic glass were followed in situ by high-temperature X-ray diffraction using synchrotron radiation at the high energy beam-line BW5 ( λ = 0.01040 nm) at the storage ring DORIS (HASYLAB, Hamburg). The experimental set-up enables to record intensities in transmission up to scattering vectors q of 200 nm -1 with a measuring time of 20 s per diagram. The crystallization starts with the formation of an extremely fine nanostructure followed by the transformation into tetragonal NiZr2-type crystals plus an unknown phase. Both phases are metastable and transform at about 1123 K into the stable equilibrium phases. The temperature dependence of the structure factor S(q) of the glass can be well described within the framework of the Debye theory. At the glass transition the first derivative dS(q)/dT changes. A Debye temperature Θ = 412 K was estimated for the glassy, and Θ = 162 K for the liquid state of the
Zr52Ti5Cu18Ni15Al10 alloy. The short-range order of the glass, of the supercooled liquid state, and
of the equilibrium melt at T = 1193 K is found to be quite similar.
Abstract: The low-temperature magnetic properties of the rare-earth intermetallic compound
system R3Pd20Si6 (R = rare earth) were studied by elastic and inelastic neutron scattering. The compounds show due to the two rare-earth sublattices built from the 4a and 8c sites in the cubic crystal structure (space group Fm-3m) successive magnetic ordering with two different propagation vectors. In this report, we give an overview of the results obtained for the magnetic structures and the crystalline electric fields in the 3-20-6-system.
Abstract: The longtime stability of copper textures has been periodically monitored over 12 years by neutron diffraction pole figure measurements on a cold rolled and a partially recrystallized copper specimen, always using the same diffractometer and the same procedure of data analysis. The texture component fractions of 'rolled' copper suffered a continuous decrease over about 8 years and seem to reverse since then. The decrease is accompanied by recrystallization from initial 3 to 34 vol. % at present. Texture changes in the partially recrystallized specimen are less pronounced. In this sample, the fraction of random orientations changed from initially 11 % to 31 % over the about first six years and followed by a decrease to 24 % at present.