| 1. |
- Bernard, M, et al.
(författare)
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Raman spectra of TiN/AlN superlattices
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 380:1-2, s. 252-255
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Tidskriftsartikel (refereegranskat)abstract
- TiN (4.5 nm)/AIN (3, 6, 22 nm) superlattices deposited by DC magnetron sputtering on MgO(001) at a temperature of 850 degreesC exhibit Raman signals. They indicate N and Ti vacancies (as in thick TiN) in TiN1-x layers (x = 3 +/- 2%). x is higher for the sample with 3-nm thick AIN layers, which is ascribed to N diffusion from AIN (standing close to the TiN interfaces) to TiN. In comparison to Raman peaks of thick ALN, there are split signals of wurzite ALN phase, and a signal from another phase, which might be defective rocksalt AIN standing close to the TiN interfaces. The Raman signals clearly show interactions between ALN and TiN layers. (C) 2000 Elsevier Science B.V. All rights reserved.
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| 2. |
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| 3. |
- Buyanova, Irina, 1960-, et al.
(författare)
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Direct experimental evidence for unusual effects of hydrogen on the electronic and vibrational properties of GaNxP1−x alloys : a proof for a general property of dilute nitrides
- 2004
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 70:24, s. 245215-245219
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Tidskriftsartikel (refereegranskat)abstract
- Direct experimental evidence for dramatic effects of hydrogen incorporation on the electronic structure and lattice properties of GaNxP1−x alloys is presented. By employing photoluminescence excitation spectroscopy, postgrowth hydrogenation is shown to reopen the band gap of the GaNP alloys and to efficiently reduce the N-induced coupling between the conduction band states. By Raman spectroscopy, these effects are shown to be accompanied by hydrogen-induced breaking of the Ga-P bond in the alloy, evident from disappearance of the corresponding vibrational mode. According to the performed Raman and x-ray diffraction measurements, the hydrogenation is also found to cause a strong expansion of the GaNP lattice, which changes the sign of strain from tensile in the as-grown GaNP epilayers to compressive in the posthydrogenated structures, due to the formation of complexes between N and H.
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| 4. |
- Carlson, Stefan, et al.
(författare)
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Beamline I811 - status report
- 2000
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Ingår i: MAX-Lab Activity Report. ; , s. 302-303
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Forskningsöversikt (refereegranskat)
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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. |
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| 7. |
- Hertz, Hans M., et al.
(författare)
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Table-top X-ray microscopy : Sources, optics and applications
- 2003
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Ingår i: Journal de Physique IV. - : EDP Sciences. - 1155-4339 .- 1764-7177. ; 104, s. 115-119
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Tidskriftsartikel (refereegranskat)abstract
- We have developed the first operative compact sub-visible-resolution x-ray microscope for the water-window region (lambda = 2.3 - 4.4 nm). The microscope is based on a 100 Hz liquid-jet-target laser-plasma x-ray source, normal-incidence multilayer condenser optics, diffractive zone plate optics and CCD detection. In the present article we emphasize the system's aspects and summarize the recent progress on the components, all aiming at the reduction of the exposure time of a few seconds, i.e., similar to bending-magnet based microscopes. This primarily includes improved laser-plasma source, improved condenser optics using Cr/Sc multilayers, and improved image handling capability using wavelet algorithms. Such compact short-exposure time microscopes would significantly increase the applicability of the technology.
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| 8. |
- Hogberg, H., et al.
(författare)
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Strain relaxation of low-temperature deposited epitaxial titanium-carbide films
- 2000
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 219:3, s. 237-244
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Tidskriftsartikel (refereegranskat)abstract
- The lattice misfit strain and relaxation during growth of 60-950 angstroms epitaxial TiC carbide films deposited by co-evaporation of C60 and Ti on MgO(0 0 1) have been studied by reciprocal space mapping (RSM) and transmission electron microscopy (TEM). All the films exhibited a strained layer growth behavior with respect to the substrate. The strain e, ranged from 2.1% for the 60 angstroms film to 0.8% for the 950 angstroms film. Initial misfit strain relaxation was by slip on {1 1 0}<1 0 1¯> and {1 1 1}<1 0 1¯>. After dislocation rearrangement the films predominantly exhibited well-developed misfit dislocations of edge type with line direction <1 0 0> along the interface plane and Burgers vectors 1/2[1 0 1¯] inclined to the interface with MgO.
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| 9. |
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| 10. |
- Jacobson, H, et al.
(författare)
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Lateral enlargement of silicon carbide crystals
- 2002
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Ingår i: Materials Science Forum, Vols. 389-393. ; , s. 39-42
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Konferensbidrag (refereegranskat)abstract
- A new growth technique for lateral enlargement of silicon carbide crystals is presented. The technique is based on sublimation growth but modified with respect to temperature gradients and geometry as compared to conventional setup. Simulation of the temperature distribution for lateral growth as well as the growth mechanism is discussed. Synchrotron white beam x-ray topographs have been evaluated concerning threading defects along the 0001 direction. Finally, a comparison between laterally grown 4H, 6H-silicon carbide and a commercial 4H-silicon carbide wafer is demonstrated, and shows that this growth technique makes it possible to enlarge seed crystals without screw dislocations and micropipes along the 0001 direction.
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