| 1. |
- IVANOV, I, et al.
(författare)
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GROWTH OF EPITAXIAL ALN(0001) ON SI(111) BY REACTIVE MAGNETRON SPUTTER-DEPOSITION
- 1995
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Ingår i: JOURNAL OF APPLIED PHYSICS. - : AMER INST PHYSICS. - 0021-8979. ; 78:9, s. 5721-5726
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 2H-AlN(0001) layers have been grown on Si(lll) by reactive magnetron sputtering from an Al target in Ar+N-2 gas mixtures at temperatures T-s=400-900 degrees C. Variations in reactive gas consumption, target voltage, and current-voltage characteristics ver
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| 2. |
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| 3. |
- Guo, JH, et al.
(författare)
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Spectroscopic study of CNx films grown by magnetron sputter deposition
- 1999
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Ingår i: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. - : ELSEVIER SCIENCE BV. - 0368-2048. ; 103, s. 551-554
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The electronic structure of carbon nitride films has been studied using soft X-ray absorption and emission spectroscopy. Resonant N K-emission spectra show a strong dependence on excitation photon energies and the substrate temperatures, while C K-emissio
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| 4. |
- Hellgren, N, et al.
(författare)
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Influence of plasma parameters on the growth and properties of magnetron sputtered CNx thin films
- 2000
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Ingår i: Journal of Applied Physics. - 0021-8979 .- 1089-7550. ; 88:1, s. 524-532
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nitride CNx thin films were grown by unbalanced dc magnetron sputtering from a graphite target in a pure N-2 discharge, and with the substrate temperature T-s kept between 100 and 550 degrees C. A solenoid coil positioned in the vicinity of the substrate was used to support the magnetic field of the magnetron, so that the plasma could be increased near the substrate. By varying the coil current and gas pressure, the energy distribution and fluxes of N-2(+) ions and C neutrals could be varied independently of each other over a wide range. An array of Langmuir probes in the substrate position was used to monitor the radial ion flux distribution over the 75-mm-diam substrate, while the flux and energy distribution of neutrals was estimated through Monte Carlo simulations. The structure, surface roughness, and mechanical response of the films are found to be strongly dependent on the substrate temperature, and the fluxes and energies of the deposited particles. By controlling the process parameters, the film structure can thus be selected to be amorphous, graphite-like or fullerene-like. When depositing at 3 mTorr N-2 pressure, with T-s> 200 degrees C, a transition from a disordered graphite-like to a hard and elastic fullerene-like structure occurred when the ion flux was increased above similar to 0.5-1.0 mA/cm(2). The nitrogen-to-carbon concentration ratio in the films ranged from similar to 0.1 to 0.65, depending on substrate temperature and gas pressure. The nitrogen film concentration did, however, not change when varying the nitrogen ion-to-carbon atom flux ratios from similar to 1 to 20. (C) 2000 American Institute of Physics. [S0021-8979(00)00413-8].
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| 5. |
- 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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| 6. |
- Henning, P, et al.
(författare)
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Compositional information from amorphous Si-Ge multilayers using high-resolution electron microscopy imaging and direct digital recording
- 1996
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Ingår i: Ultramicroscopy. - 0304-3991. ; 66:3-4, s. 221-235
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Tidskriftsartikel (refereegranskat)abstract
- A simple method for extracting compositional information from high-resolution electron microscopy images of an amorphous two-element system using a slow-scan CCD camera has been developed. The method has been evaluated on amorphous Si/Ge multilayers. The characterisation of the multilayers provided information about thickness of the layers, maximum concentrations within the layers and elemental profiles across the boundaries. It was shown that the intensity profiles could be corrected for the wedge shape of the specimen and that the derived compositional profile was independent of average sample thickness variation within the range of the cross-section sample thickness.The results have been compared to analysis performed by Auger electron spectroscopy depth profiling on as-prepared multilayers as well as by energy-dispersive X-ray analysis and electron energy filtered images of cross-sections. The proposed HREM image contrast evaluation method gave spatial resolution in chemical analysis across the thin layers comparable in accuracy to the other methods, whereas the oscillation amplitude for the concentration is slightly less due to specimen preparation artifacts.
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| 7. |
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| 8. |
- Hultman, Lars, et al.
(författare)
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Fullerene-like carbon nitride : A resilient coating material
- 2003
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Ingår i: MRS bulletin. - 0883-7694 .- 1938-1425. ; 28:3, s. 194-202
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nitride is an emerging material for wear-resistant coatings. The fullerene-like CNx compounds generally exhibit extreme elasticity in combination with a low work of indentation hardness. Yet CNx shows a low-to-moderate resistance to penetration, depending on deposition conditions. Since the deformation energy is predominantly stored elastically, the material possesses an extremely resilient character. This new class of materials consists of sp(2)-coordinated basal planes that are buckled from the incorporation of-pentagons and cross-linked at sp(3)-hybridized C sites, both of which are caused by structural incorporation of nitrogen. Carbon nitride thus deforms elastically due to bending of the structural units. The orientation, radius of curvature of the basal planes, and the degree of cross-linking between them defines the structure and properties of the material. Due to the unique deformation behavior, the hardness requires special care to assess, but can be very high for films with a large degree of cross-linking. This article is a review of the research on CNx films deposited by reactive magnetron sputtering, with examples from our recent work. The findings are significant for the design of fracture-tough materials.
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| 9. |
- Hultman, L, et al.
(författare)
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Growth and electronic properties of epitaxial TiN thin films on 3C-SiC(001) and 6H-SiC(0001) substrates by reactive magnetron sputtering
- 1996
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Ingår i: Journal of Materials Research. - 0884-2914. ; 11:10, s. 2458-2462
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial TiN films were grown on cubic (3C)-SiC(001) and hexagonal (6H)-SiC(0001) substrates by ultrahigh vacuum reactive magnetron sputtering from a Ti target in a mixed Ar and N2 discharge at a substrate temperature of 700°C. Cross-sectional transmission electron microscopy, including high-resolution imaging, showed orientational relationships TiN(001) ∥ 3C-SiC(001), and TiN[110] ∥ 3C-SiC[110], and TiN(111) ∥ 6H-SiC(0001) and TiN[110],[101] ∥ 6H-SiC[1210]. In the latter case, twin-related TiN domains formed as the result of nucleation on SiC terraces with an inequivalent stacking sequence of Si and C. The TiN/SiC interface was locally atomically sharp for both SiC polytypes. Defects in the TiN layers consisted of threading double positioning domain boundaries in TiN(111) on 6H-SiC. Stacking faults in 3C-SiC did not propagate upon growth of TiN. Room-temperature resistivity of TiN films was ρ = 14 μΩ cm for 6H-SiC(0001) and ρ = 17 μΩ cm for 3C-SiC(001) substrates. Specific contact resistance of TiN to 6H-SiC(0001) was 1.3 × 10-3 Ω cm2 for a 6H-SiC substrate with an n-type doping of 5 × 1017 cm-3.
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| 10. |
- Johansson, MP, et al.
(författare)
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Template-synthesized BN : C nanoboxes
- 2000
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Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 76:7, s. 825-827
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Tidskriftsartikel (refereegranskat)abstract
- Box-shaped nanostructures of B-C-N compounds were synthesized by reactive sputtering of boron carbide in mixed argon and nitrogen discharges. Transmission electron microscopy showed that these nanoboxes were grown on self-patterned NaCl substrate with projected areas ranging from similar to 1x10(2) to similar to 5x10(4) nm(2), sizes 50-100 nm, and number density similar to 100 mu m(-2). Electron energy loss spectroscopy revealed a phase separation of BN and C:N layers. (C) 2000 American Institute of Physics. [S0003-6951(00)00507-6].
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| 11. |
- Karlsson, L, et al.
(författare)
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Growth, microstructure, and mechanical properties of arc evaporated TiCxN1-x (0 <= x <= 1) films
- 2000
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Ingår i: Surface & Coatings Technology. - 0257-8972 .- 1879-3347. ; 126:1
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Tidskriftsartikel (refereegranskat)abstract
- TiCxN1-x films with x ranging from 0 to 1 were grown by arc evaporation by varying the flow ratio between the reactive gases. The substrates were cemented carbide inserts (WC-6 wt.% Co) which were negatively biased at 400 V, resulting in a deposition temperature of similar to 550 degrees C. The film composition, as measured by glow discharge optical emission spectroscopy, was found to vary almost linearly with the gas flow ratio. Cross-sectional transmission electron microscopy in combination with X-ray diffraction (XRD) showed that the films were of single-phase NaCl-structure with a dense columnar microstructure. The intrinsic stress analyzed using the XRD sin(2)psi method, was found to have a maximum of - 5.9 GPa in the composition range of 0.4 less than or equal to x less than or equal to 0.7 which correlated with a maximum in XRD peak broadening due to inhomogeneous strains. The hardness and Young's modulus of the as-deposited TiCxN1-x films were measured by the nanoindentation technique. A maximum in hardness of 45 GPa was found at the same composition range (0.4 Ix I 0.7) as the intrinsic stress maximum. The hardness for x = 0 (TiN) and x = 1 (TiC) were found to be 28 and 36 GPa, respectively. The Young's modulus was constant similar to 610 GPa for films with compositions up to x = 0.6, thereafter it decreased to 540 GPa at x = 1. The increase in intrinsic stress with increasing carbon content is suggested to be due to increased stability of defects created from the collision cascade or/and by a change in the defect structure itself. The fact that hardness showed a maximum at the same composition as residual stress and FWHM indicates that obstruction on dislocation movement has a major influence on the hardness of these films. (C) 2000 Published by Elsevier Science S.A. All rights reserved.
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| 12. |
- Lin, N, et al.
(författare)
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In situ scanning tunneling microscopic and spectroscopic investigation of magnetron-sputtered C and CN thin films
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 61:7, s. 4898-4903
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Tidskriftsartikel (refereegranskat)abstract
- Carbon and carbon nitride films, grown in argon or nitrogen discharges by reactive Jc magnetron sputtering of a graphite target, were characterized by in situ scanning tunneling microscopy. When the growth temperature increased from ambient to 800 degrees C, we observed a topographic evolution of the carbon films from an amorphous to a graphitelike structure, and further to a distorted-graphitic phase with curved and intersecting basal planes, and finally to a surface containing nanotubes and nanodomes. When nitrogen was incorporated into the films, distortion of the graphitic basal planes occurred at a lower temperature compared to the pure carbon case. At temperatures of similar to 200 degrees C and above, regions of a nongraphitic phase, containing a high degree of carbon sp(3) bonds were observed. Spatially resolved tunneling spectroscopic measurements indicated that the band gaps were 0, similar to 0-0.6 eV, and similar to 0.4-2.0 eV for graphitelike structures, the distorted-graphitic phase, and the nongraphitic phase, respectively. Together with ex sial x-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy measurements, the results suggest that the incorporation of nitrogen promotes bending of the graphitic basal planes and thereby facilitates the formation of three-dimensional covalently bonded networks with a high degree of sp(3)-coordinated carbon atoms.
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| 13. |
- Sjostrom, H, et al.
(författare)
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Growth of CNxHy films by reactive magnetron sputtering of carbon in Ar/NH3 discharges
- 1996
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Ingår i: JOURNAL OF MATERIALS RESEARCH. - : MATERIALS RESEARCH SOCIETY. ; 11:4, s. 981-988
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Results on hydrogenated carbon nitride (CNxHy) thin films grown by reactive magnetron sputtering in a mixed Ar/NH3 discharge are reported. Depending on the growth temperature (T-s) and negative substrate bias voltage (V-s), both the composition and the mi
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| 14. |
- Sjöström, H., et al.
(författare)
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Microstructure of amorphous C:H and metal-containing C:H films deposited on steel substrates
- 1993
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Ingår i: Thin Solid Films. - 0040-6090. ; 232:2, s. 169-179
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Tidskriftsartikel (refereegranskat)abstract
- Cross-sectional transmission electron microscopy (XTEM), including high-resolution microscopy (HREM), was employed to characterize the interface between different amorphous hydrogenated carbon (a-C:H) films and steel substrates. Additional analyses using Auger electron spectroscopy (AES) and X-ray diffraction (XRD) were also performed. Films were deposited both by high-energy (50 keV) nitrogen ion-beam decomposition of large hydrocarbon molecules and by magnetron plasma decomposition of C2H2 in mixed Ar-C2H2 discharges. The latter method was also used to deposit Mo- or W-containing a-C:H films (Me-C:H films) onto steel substrates with interlayers of the pure metals between the substrate and Me-C:H film. The films were found to be truly amorphous except for the cases of the metal-containing films, where 1–2 nm crystalline clusters were present in an a-C:H matrix. In the case of Mo the clusters were identified from HREM micrographs to have a bcc-like structure, characteristic of metallic Mo. The metal interlayers had a columnar microstructure with column widths of ∼ 30 nm. The interfaces between the Mo and W interlayers and the a-C:H films were found to extend over 20–40 nm with a gradual crystalline-to-amorphous transition. In most of the a-C:H film-substrate interface regions a thin layer ( < 10 nm) was observed which was predominantly amorphous but contained a small fraction of crystalline grains. AES showed an increase of both O and N close to the interface. However, for the cases with Mo and W interlayers, the substrate surface contaminants were less localized, and on some parts of the substrate surface the lattice fringes of the substrate and metal interlayer phase were continuous across a sharp interface.
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| 15. |
- Sjöström, H, et al.
(författare)
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Reactive magnetron sputter deposition of CNx films on Si(001) substrates : film growth, microstructure and mechanical properties
- 1994
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090. ; 246:1-2, s. 103-109
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Tidskriftsartikel (refereegranskat)abstract
- There is currently considerable interest in producing new materials with extreme combinations of mechanical properties such as high hardnesses and moduli. One example of such a material is crystalline C3N4, which has been predicted to have a bulk modulus higher than that of diamond. In this paper we report on experiments carried out to synthesize CNx thin films. The films were grown in an unbalanced magnetron-sputtering system by reactive sputtering of C in N2 discharges. Si(001) substrates with the native oxide removed by thermal desorption and then kept at temperatures ranging from 150 to 600°C and substrate bias voltages Vs between 7.5 and -200 V were used. The films were analysed using X-ray diffraction, transmission electron microscopy (TEM). Auger electron spectroscopy, Rutherford backscattering and nano-indentation tests. Typically the films were grown at rates of 5 nm s-1 to total thicknesses of 300 nm. Owing to an extensive re-sputtering, only low negative bias voltages (-80
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| 16. |
- Svedberg, EB, et al.
(författare)
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Epitaxial growth of UHV magnetron sputtered Mo thin films on MgO(001) substrates, oxygen segregation and surface reconstructions
- 1999
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Ingår i: Surface Science. - 0039-6028 .- 1879-2758. ; 443:1-2, s. 31-43
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Tidskriftsartikel (refereegranskat)abstract
- Studies of epitaxial growth of Mo thin films on MgO(001) substrates by ultrahigh Vacuum (UHV) d.c. magnetron sputter deposition have shown independently by in situ low energy electron diffraction (LEED), scanning tunnelling microscopy (STM) and time-resolved in situ reflection high-energy electron diffraction (RHEED) measurements that oxygen is present on the Mo surface during the initial stages of growth. Oxygen induced reconstructions are only found for films thinner than similar to 50 nm, and it is shown that the oxygen originates from the MgO substrate. The oxygen is causing the growing film surface to continuously reconstruct with the (root 5 x root 5)R26 degrees 33', p(2 x 2) and c(2 x 2) structures indicating O coverages ranging from similar to 0.8-1.0 ML. STM measurements confirm earlier X-ray diffraction (XRD) and STM measurements of the (root 5 x root 5)R26 degrees 33' reconstruction and show for the first time STM images of the surface structures where p(2 x 2) and c(2 x 2) reconstructions are present. Based on our STM data we suggest surface models for the p(2 x 2) and c(2 x 2) reconstructions. The STM measurements also revealed surfaces randomly interspersed with apparent 2x2 'holes' not visible by techniques such as LEED due to their non-periodic nature. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
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| 17. |
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| 18. |
- Zheng, WT, et al.
(författare)
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Chemical bonding in carbon nitride films studied by X-ray spectroscopies
- 2001
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Ingår i: DIAMOND AND RELATED MATERIALS. - : ELSEVIER SCIENCE SA. - 0925-9635. ; 10:9-10, s. 1897-1900 Language: English
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Tidskriftsartikel (refereegranskat)abstract
- Carbon nitride films are deposited using dc magnetron sputtering in a N-2 discharge. The nature of chemical bonding of the films is investigated using X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure, and X-ray emission spectros
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| 19. |
- Zheng, WT, et al.
(författare)
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Nitrogen 1s electron binding energy assignment in carbon nitride thin films with different structures
- 1997
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Ingår i: JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. - : ELSEVIER SCIENCE BV. - 0368-2048. ; 87:1, s. 45-49
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Carbon nitride thin films deposited by dc unbalanced magnetron sputtering have been analyzed by high-resolution X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The XPS data show that N 1s binding stares depend on substrate temperature (T-s)
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| 20. |
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