| 1. |
- Chun, JS, et al.
(författare)
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Synchrotron x-ray diffraction and transmission electron microscopy studies of interfacial reaction paths and kinetics during annealing of fully-002-textured Al/TiN bilayers
- 2001
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - 0734-2101 .- 1520-8559. ; 19:1, s. 182-191
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Tidskriftsartikel (refereegranskat)abstract
- Dense fully-002-textured polycrystalline TiN layers, 110 nm thick with a N/TI ratio of 1.02+/-0.03, were grown on SiO2 by ultrahigh vacuum magnetically unbalanced magnetron sputter deposition at T-s = 450 degreesC in pure N-2 utilizing high N-2(+)/Ti Aux ratios and low energy (E-N2(+) = 20 eV) ion irradiation of the growing film. Al overlayers, 160 nm thick and possessing a strong 002 texture inherited from the underlying TiN, were then deposited at T-s = 100 degreesC without breaking vacuum. Synchrotron x-ray diffraction was used to follow interfacial reaction paths and kinetics during postdeposition annealing as a function of time (t(a) = 200 - 1200 s) and temperature (T-a = 500 - 580 degreesC). Changes in bilayer microstructure and microchemistry were investigated using transmission electron microscopy (TEM) and scanning TEM to obtain compositional maps of cross-sectional and plan-view specimens by energy dispersive x-ray analysis. The initial bilayer reaction step during annealing involves the formation of a continuous AIN interfacial layer which, due to local epitaxy with the TIN underlayer, grows with the metastable zinc-blende structure up to a thickness x similar or equal to3-5 nm, and with the wurtzite structure thereafter. Ti atoms released during AIN formation diffuse into the Al layer leading to supersaturation followed by the nucleation of dispersed regions of tetragonal Al3Ti with inherited 002 preferred orientation. The aluminide domains grow rapidly until they reach the free surface, thereafter growth is two dimensional as Al3Ti grains spread radially. The overall activation energy for Al3Ti formation and growth is 1.8+/-0.1 eV. In situ synchrotron x-ray diffraction analyses during thermal ramping show that the onset temperature for interfacial reactions was increased by more than 100 degreesC for fully dense completely 002-textured bilayers compared to Ill-textured bilayers deposited by conventional reactive sputter deposition. (C) 2001 American Vacuum Society.
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| 2. |
- Broitman, E., et al.
(författare)
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Structural and mechanical properties of diamond-like carbon films deposited by direct current magnetron sputtering
- 2003
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Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 21:4, s. 851-859
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Tidskriftsartikel (refereegranskat)abstract
- A systematic study of physical properties of sputter-deposited DLC films was performed as a function of flux ratio and ion energy. The energy and flux ions and neutral atoms impinging on the surface of the growing films were deduced from Langmuir probe measurements and theoretical calculations. The bombardment of growing films by the energetic particles led to changes in microstructure and mechanical properties. Results suggest that the presence of defective graphite formed by subplanted C and Ar atoms is the dominant influence on the mechanical properties of the DLC films.
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| 3. |
- Broitman, E., et al.
(författare)
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Structural, electrical, and optical properties of diamondlike carbon films deposited by dc magnetron sputtering
- 2003
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Ingår i: Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The electrical and optical properties of diamondlike carbon films deposited by direct current magnetron sputtering on Si substrates at room temperature have been measured as a function of the ion energy (Eion) and ion-to-carbon flux (Jion/JC). The results show that, in the ranges of 5 eV⩽Eion⩽85 eV and 1.1⩽Jion/JC⩽6.8, the presence of defective graphite formed by subplanted C and Ar atoms, voids, and the surface roughness, are the dominant influences on the resistivity and optical absorption
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| 4. |
- Cederbrant, Karin, et al.
(författare)
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Cytokine production, lymphocyte proliferation and T-cell receptor Vbeta expression in primary peripheral blood mononuclear cell cultures from nickel-allergic individuals
- 2003
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Ingår i: International Archives of Allergy and Immunology. - : S. Karger AG. - 1018-2438 .- 1423-0097. ; 132:4, s. 373-379
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Tidskriftsartikel (refereegranskat)abstract
- Background: Clinical history and patch test constitute the two cornerstones in the diagnosis of nickel (Ni) allergy. Due to technical and interpretative limits of the patch test, the in vitro lymphocyte transformation test (LTT) has been developed for confirming contact allergy, however, most studies show an overlap in lymphocyte proliferation between Ni-allergic and nonallergic subjects using the LTT. The aim of this study was to see if the secretion of cytokines, especially interleukin (IL)-10 and IL-17, or the use of T-cell receptor (TCR) V▀ families in Ni-stimulated primary peripheral blood mononuclear cell (PBMC) cultures might be more useful for discriminating between allergic and nonallergic subjects. Methods: Ni2+-stimulated primary PBMC cultures derived from female subjects diagnosed as Ni-allergic (n = 5) or nonallergic (n = 5) on the basis of a positive or negative patch test were assessed for cell proliferation by tritiated thymidine incorporation and for production of interferon-?, IL-4, IL-10 and IL-17 in the culture supernatant by ELISA. The immunophenotype and TCR-V▀ family affiliation of the Ni2+-induced lymphoblasts were determined by flow cytometry. Results: Lymphocytes from Ni-allergic individuals challenged with a high and a low concentration of Ni showed significantly higher cell proliferation than lymphocytes from nonallergic individuals, but all subjects showed a positive LTT result (stimulation index>2). We found a significantly higher release of IL-10 in Ni2+-treated cultures from Ni-allergic compared with nonallergic subjects that provided better separation between individuals in the two groups than did lymphocyte proliferation. The proliferating lymphoblasts were predominantly CD4+, and in 2 of the 5 Ni-allergic subjects, but in none of the 5 nonallergic subjects, the CD4+ lymphoblasts showed a dominance of TCR-V▀17. Conclusions: Determination of IL-10 production in primary PBMC cultures is a potentially promising in vitro method for discrimination of Ni allergy in females, as compared with cell proliferation. Copyright ⌐ 2003 S. Karger AG, Basel.
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| 5. |
- Engstrom, C., et al.
(författare)
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Design, plasma studies, and ion assisted thin film growth in an unbalanced dual target magnetron sputtering system with a solenoid coil
- 2000
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Ingår i: Vacuum. - 0042-207X .- 1879-2715. ; 56:2, s. 107-113
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Tidskriftsartikel (refereegranskat)abstract
- An original design and solution to the problem of magnetic field interactions in a vacuum chamber between two unbalanced magnetron sputtering sources and a solenoid coil serving to increase plasma density in near substrate position, is presented. By changing the solenoid coil current strength and direction, plasma growth conditions in an argon discharge and Ti-magnetron cathodes were found to vary in a broad region. Langmuir probe analysis shows that an increase in the coil current from 0 to 6 A caused plasma and substrate floating potentials to change from -7 to -30 V and from +1 to -10 V, respectively, as well as increasing the ion densities to a biased substrate from 0.2 to 5.2 mA cm-2 for each of the magnetrons. By using a ferro-powder magnetic field model, as well as finite element method analysis, we demonstrate the interference of the three magnetic fields - those of the two magnetrons and the solenoid coil. X-ray diffraction and transmission electron microscopy were used to study the microstructure and morphology of Ti-films grown under different ion bombardment conditions. At low Ar-ion-to-Ti-atom arrival rate ratios, Jion/Jn to approximately 1.5, at the substrate, variations of the ion energy, Eion, from 8 to 70 eV has only a minor effect on the microstructure and film preferred crystallographic orientation, resulting in an open/porous structure with defect-rich grains. At a higher Jion/Jn value of approximately 20, films with a well-defined dense structure were deposited at ion energies of 80 eV. The increase in ion flux also resulted in changes of the Ti film preferred orientation, from an (0 0 0 2) preferred orientation to a mixture of (0 0 0 2) and (1 0 1¯ 1) orientations.
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| 6. |
- Engstrom, C, et al.
(författare)
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High-temperature stability of epitaxial, non-isostructural Mo/NbN superlattices
- 2000
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 15:2, s. 554-559
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Tidskriftsartikel (refereegranskat)abstract
- The effect of 1000 degrees C vacuum annealing on the structure and hardness of epitaxial Mo/NbN superlattice thin films was studied. The intensity of superlattice satellite peaks, measured by x-ray diffraction, decreased during annealing while new peaks corresponding to a MoNbN ternary phase appeared. The results are consistent with the Mo-Nb-N phase diagram, which shows no mutual solubility between Mo, NbN, and MoNbN. Even after 3-h anneals and a loss of most of the superlattice peak intensity, the room-temperature hardness was the same as for as-deposited superlattices, The retained hardness suggests that a residual nanocomposite structure is retained even after the formation of the ternary structure.
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| 7. |
- Grillo, SE, et al.
(författare)
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Monitoring the structural and chemical properties of CNx thin films during in situ annealing in a TEM
- 2001
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Ingår i: European Physical Journal. - 1286-0042 .- 1286-0050. ; 13:2, s. 97-105
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nitride films synthesised by magnetron sputtering at different substrate temperatures have been studied using electron energy loss spectroscopy (EELS) during annealing performed in situ in a transmission electron microscope (TEM). The proportion of sp(2) hybridised carbon slightly decreases initially during heating, presumably because of the removal of defects in the structure, whilst it increases at higher temperatures when graphitisation tends to take place, as confirmed by high resolution electron microscopy (HREM). Substantial amounts of nitrogen (up to similar to 80%) are removed following annealing at 1000 degreesC. A corresponding decrease in the pre-peak of the nitrogen spectra suggests that pyridine-like N is released by annealing. As this peak component decreases, a second peak, of weaker intensity, is becoming apparent in the EELS spectra when the films are heated at temperatures above approximately 700 degreesC. The possibility has been suggested that this corresponds to N substituted for C in a graphitic structure, with possibly also some N-2 contributing to the peak.
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| 8. |
- Hellgren, N, et al.
(författare)
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Thermal stability of carbon nitride thin films
- 2001
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 16:11, s. 3188-3201
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Tidskriftsartikel (refereegranskat)abstract
- The thermal stability of carbon nitride films, deposited by reactive direct current magnetron sputtering in N-2 discharge, was studied for postdeposition annealing temperatures T-A up to 1000 degreesC. Films were grown at temperatures of 100 degreesC (amorphous structure) and 350 and 550 degreesC (fullerenelike structure) and were analyzed with respect to thickness, composition, microstructure, bonding structure, and mechanical properties as a function of T-A and annealing time. All properties investigated were found to be stable for annealing up to 300 degreesC for long times (> 48 h). For higher T-A, nitrogen is lost from the films and graphitization takes place. At T-A = 500 degreesC the graphitization process takes up to 48 h while at T-A = 900 degreesC it takes less than 2 min. A comparison on the evolution of x-ray photoelectron spectroscopy, electron energy loss spectroscopy and Raman spectra during annealing shows that for T-A > 800 degreesC, preferentially pyridinelike N and -C equivalent toN is lost from the films, mainly in the form of molecular N-2 and C2N2, while N substituted in graphite is preserved the longest in the structure. Films deposited at the higher temperature exhibit better thermal stability, but annealing at temperatures a few hundred degrees Celsius above the deposition temperature for long times is always detrimental for the mechanical properties of the films.
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| 10. |
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