| 41. |
- Ni, Wei-Xin, et al.
(författare)
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Light emitting SiGe/i-Si/Si : Er
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 369:1, s. 414-418
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Tidskriftsartikel (refereegranskat)abstract
- p+-SiGe/i-Si/n-Si:Er:O/n+-Si tunneling diodes have been processed using layer structures prepared by molecular beam epitaxy (MBE). Electroluminescence has been observed at room temperature from these devices at reverse bias. The devices have been used for characterizing the optical activation of Er3+ ions in MBE Si:Er:O layers grown at different conditions. In the range of 400-575 °C, a high substrate temperature is favored for formation of Er emission centers, but this is limited by the silicidation process occurring above 600 °C. Several important device parameters such as the impact excitation cross section and various EL decay processes have been carefully studied. A fast decay (approximately 4 µs) due to the Auger carrier transfer process is observed.
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| 42. |
- Niklasson, Gunnar A., et al.
(författare)
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Surface roughness of pyrolytic tin dioxide films evaluated by different methods
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 359:2, s. 203-209
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Tidskriftsartikel (refereegranskat)abstract
- The scaling of surface roughness in thin spray pyrolyzed fluorinated tin dioxide films of different thicknesses was obtained from atomic force microscopy. The data show that, within experimental uncertainties, the effective dimensionality of the surface is 2; hence no evidence of fractal surface roughness was found. Other methods – based upon light scattering and cyclic voltammetry – gave additional information on the surface topography. Cyclic voltammetry measurements show that the reaction sites on the surface are distributed in a fractal structure and may be identified with hillocks seen in surface reliefs.
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| 43. |
- Odén, Magnus, 1965-, et al.
(författare)
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Microstructure-property relationships in arc-evaporated Cr-N coatings
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 377-378, s. 407-412
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Tidskriftsartikel (refereegranskat)abstract
- Chromium nitride (Cr-N) coatings have received increased attention for tribological applications due to their favorable properties including wear resistance, toughness and oxidation resistance. These properties, in turn, can be strongly influenced by the coating microstructure and residual stress resulting from deposition and subsequent processing operations. In this study these microstructure-property correlations are investigated in Cr-N coatings grown by arc-evaporation. Prominent as-deposited features include formation of metastable amounts of the cubic d-CrN phase, and high levels of compressive residual stress and defect density. During annealing up to 650 ░C the residual stress and defect density decrease substantially, accompanied by a diffusion-based d-CrN to ▀-Cr2N phase transformation and equiaxed grain formation. The effects of these microstructural modifications on the hardness, fracture and wear properties of the coatings are evaluated using a combination of nanoindentation, scratch and pin-on-disk testing. Appreciable changes in these properties are found after annealing, and are correlated to the Cr-N microstructure. As-deposited coating hardness is enhanced by high levels of lattice defect density, with both decreasing concomitantly during annealing. Scratch results show that resistance to cohesive flaking is increased by annealing, suggesting ductility increases via defect annealing and equiaxed grain formation. Finally, the wear rate under dry sliding generally increased with annealing temperature, although wear rates of all Cr-N coatings significantly outperformed TiN tested under identical conditions.
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| 44. |
- Olsson, M.K., et al.
(författare)
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Mechanisms for reactive DC magnetron sputtering of elements with different atomic masses : Large area coatings of Al oxide and W oxide
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 371:1, s. 86-94
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Tidskriftsartikel (refereegranskat)abstract
- Stoichiometric Al and W oxide films are prepared with high stability from the metallic state of the cathodes using conventional reactive DC magnetron sputtering on an industrial prototype scale. While for the Al, increased target power is a trivial way to increase growth rates, W oxide sputtering of optically functional films with sufficiently amorphous structure is severely limited by the effect of gas rarefaction at high powers. Choosing an appropriate working gas pressure and a source-to-substrate distance, which facilitates the gas scattering allows the deposition of homogeneous stoichiometric tungsten oxide films in a stable condition with a relatively high discharge current. Optimization of the process parameters with respect to film properties and efficiency of the deposition process is discussed.
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| 45. |
- Palmquist, J.-P., et al.
(författare)
-
Deposition of epitaxial ternary transition metal carbide films
- 2002
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 405, s. 122-128
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Tidskriftsartikel (refereegranskat)abstract
- Thin epitaxial carbide films have been deposited in UHV by co-evaporation of Mo, Nb, Ti and V, with C60 as carbon source. Two separate systems were studied, Ti1-xVxCy on MgO(001) and Nb1-xMoxCy on MgO(111). We demonstrate the possibility to tune the cell parameter of an epitaxial ternary carbide film by control of the composition. Analysis with reciprocal space mapping show that deposition of Ti0.34V0.66C0.81 at 500 °C yields a strain-free film with perfect match towards the MgO(001) substrate. Also, a good manual control of the individual fluxes allows the design of tailor-made compositional gradient structures. An epitaxial linear carbide gradient film going from TiC to VC was deposited at 500 °C. Furthermore, the low deposition temperature allows the deposition of metastable carbide structures. This was shown with epitaxial growth of a Nb1-xMoxCy film at 500 and 600 °C. © 2002 Elsevier Science B.V. All rights reserved.
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| 46. |
- Palmquist, J.-P., et al.
(författare)
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Magnetron sputtered W-C films with C60 as carbon source
- 2003
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 444:1-2, s. 29-37
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Tidskriftsartikel (refereegranskat)abstract
- Thin films in the W–C system were prepared by magnetron sputtering of W with coevaporated C60 as carbon source. Epitaxial deposition of different W–C phases is demonstrated. In addition, nanocrystalline tungsten carbide film growth is also observed. At low C60/W ratios, epitaxial growth of α-W with a solid solution of carbon was obtained on MgO(001) and Al2O3(001) at 400 °C. The carbon content in these films (10–20 at.%) was at least an order of magnitude higher than the maximum equilibrium solubility and gives rise to an extreme hardening effect. Nanoindentation measurements showed that the hardness of these films increased with the carbon content and values as high as 35 GPa were observed. At high C60/W ratios, films of the cubic β-WC1−x (x=0–0.6) phase were deposited with a nanocrystalline microstructure. Films with a grain size <30 Å were obtained and the hardness of these films varied from 14 to 24 GPa. At intermediate C60/W ratios, epitaxial films of hexagonal W2C were deposited on MgO(111) at 400 °C. Polycrystalline phase mixtures were obtained on other substrates and hexagonal WC could be deposited as minority phase at 800 °C.
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| 47. |
- Park, Jiwoong, et al.
(författare)
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Wiring up single molecules
- 2003
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 438-439, s. 457-461
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of using single molecules as active elements of electronic devices offers a variety of scientific and technological opportunities. In this article, we discuss transistors, where electrons flow through discrete quantum states of a single molecule. First, we will describe molecules, where current flows through one cobalt atom surrounded by two insulating terpyridyl ligands. Depending on the length of the insulating part of the molecules, two different behaviors are observed: Coulomb blockade for a longer molecule and the Kondo effect for a shorter molecule. We will also discuss measurements of the C70 fullerene and its dimer (C140). In C140 devices, the transport measurements are affected by an intercage vibrational mode that has an energy of 11 meV. We observe a large current increase when this mode is excited, indicating a strong coupling between the electronic and mechanical degrees of freedom in C140 molecules.
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| 48. |
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| 49. |
- Radnoczi, G., et al.
(författare)
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Structure of DC sputtered Si-C-N thin films
- 2003
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 440:1-2, s. 41-44
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Tidskriftsartikel (refereegranskat)abstract
- Si-C-N films of maximum 65 at.% of Si and maximum 40 at.% of N were prepared by reactive magnetron sputtering and their fine structure was investigated by high-resolution transmission electron microscopy. For compositions, where C-C and C-N bonds prevail, the films had anisotropic structure on the atomic scale, composed of curved graphitic layers, aligned parallel to the substrate normal. An isotropic structure was detected in the middle of the compositional triangle. On a larger scale, a columnar morphology, aligned in the direction of the deposition flux was formed in films containing more than 15 at.% of Si. Singular or simultaneous appearance of the above structures depended on film composition. © 2003 Elsevier B.V. All rights reserved.
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| 50. |
- Rantzer, Annika, 1971-, et al.
(författare)
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Optical properties of intrinsic and doped a-Si:H films grown by d.c. magnetron sputter deposition
- 2001
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 394:1-2, s. 255-262
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Tidskriftsartikel (refereegranskat)abstract
- Thin films of intrinsic, B- and P-doped a-Si:H were grown by d.c. magnetron sputter deposition. The doping was accomplished by doped targets and co-sputtering Si and B4C. Spectroscopic ellipsometry was used for optical characterization and multiple sample analysis was applied to extract the dielectric functions of intrinsic films with 8–10 at.% hydrogen content, boron doped films with 2.2 at.% hydrogen and phosphorous-doped films with hydrogen contents of 10–15 at.%. One of the phosphorous-doped films was micro-crystalline. Hydrogen content was determined by nuclear reaction analysis. From the obtained optical properties the absorption and the optical gap were studied addressing p–i–n diode applications. The optical gaps for intrinsic a-Si:H material were 1.88±0.03 eV as determined by Tauc analysis and 1.45±0.06 eV by applying Cody analysis.
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