| 1. |
- Ahrens, J., et al.
(författare)
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Results from the Antarctic muon and nuetrino detector array
- 2003
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Ingår i: Nuclear physics B, Proceedings supplements. - : Elsevier. - 0920-5632 .- 1873-3832. ; 118, s. 371-379
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Tidskriftsartikel (refereegranskat)abstract
- We show new results from both the older and newer incarnations of AMANDA (AMANDA-B10 and AMANDA-II, respectively). These results demonstrate that AMANDA is a functioning, multipurpose detector with significant physics and astrophysics reach. They include a new higher-statistics measurement of the atmospheric muon neutrino flux and preliminary results from searches for a variety of sources of ultrahigh energy neutrinos: generic point sources, gamma-ray bursters and diffuse sources producing muons in the detector, and diffuse sources producing electromagnetic or hadronic showers in or near the detector.
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| 5. |
- Axelson, Olav, 1937-, et al.
(författare)
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Regulatory toxicology and pharmacology.
- 2003
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Ingår i: International journal of occupational and environmental health. - 1077-3525 .- 2049-3967. ; 9, s. 386-389
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Tidskriftsartikel (refereegranskat)
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| 10. |
- Jacobson, H., et al.
(författare)
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Doping-induced strain in N-doped 4H-SiC crystals
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:21, s. 3689-3691
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Tidskriftsartikel (refereegranskat)abstract
- Stress in epitaxial layers due to crystal lattice mismatch directly influences the growth, structure, and basic electrophysical parameters of epitaxial films and also to a large extent the degradation processes in semiconductor devices. In this letter, we present a theoretical model for calculating the induced lattice compression due to N doping and the critical thickness concerning formation of misfit dislocations in homoepitaxial 4H–SiC layers with different N-doping levels. For example: The model predicts that substrates with a N concentration of 3×1019 cm-3 induce misfit dislocations when the epilayer thickness reaches ∼10 μm. Also, the N-doping concentration in the 1×1018–1×1019 cm-3 range yields a strain that not will cause misfit dislocactions at the substrate and epilayer interface until an epilayer thickness of 200–300 μm is reached. Supporting evidence of the induced lattice compression due to N doping have been done by synchrotron white-beam x-ray topography on samples with different N-doping levels and are compared with the predicted results from the model
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| 11. |
- Jacobson, H., et al.
(författare)
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Lateral enlargement of silicon carbide crystals
- 2004
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 270:1-2
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Tidskriftsartikel (refereegranskat)abstract
- A new growth technique for lateral enlargement of silicon carbide crystals is presented and evaluated. The technique is based on PVT 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. High-resolution X-ray diffraction and synchrotron white beam X-ray topography have been evaluated concerning structural defects. The results show that this growth technique makes it possible to enlarge seed crystals without threading screw dislocations and micropipes along the 0001 direction, but stacking faults are introduced due to the crystal stacking sequence along the <11¯00> directions. © 2004 Elsevier B.V.
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| 12. |
- Jacobson, H., et al.
(författare)
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Properties and origins of different stacking faults that cause degradation in SiC PiN diodes
- 2004
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 95:3, s. 1485-1488
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Tidskriftsartikel (refereegranskat)abstract
- Different properties of the reported stacking faults (SFs) and that both these types of SF are present in the material after electrical degradation of pin diodes are shown. One is caused by perfect dislocations, deflected or misfit dislocation that had dissociated into two partial dislocations. The partials are assumed to be close to each other with a separation below the detection limit of the SWBT measurements. Thus, enough energy is provided and the leading partial moves away from the other partial and forms the extended SF.
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| 13. |
- Jacobson, Herbert, et al.
(författare)
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Properties of different stacking faults that cause degradation in SiC PiN diodes
- 2003
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Ingår i: Materials Science Forum, Vols. 433-436. ; , s. 913-916
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Konferensbidrag (refereegranskat)abstract
- The electrical degradation of 4H-SiC PiN diodes has recently attracted a large interest and is a critical material problem for high power applications. The degradation is observed as an increased forward voltage drop after forward injection operation. In this paper we present the identity, properties and origin of stacking faults with different nature that cause degradation of 4H-SiC PiN diodes.
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| 14. |
- Jacobson, H., et al.
(författare)
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Structural impact of LPE buffer layer on sublimation grown 4H-SiC epilayers
- 2003
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Ingår i: Journal of Crystal Growth. - 0022-0248 .- 1873-5002. ; 256:3-4, s. 276-282
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this work was to study the effect of a liquid phase epitaxy buffer layer on the development of defects in sublimation grown epitaxial layers of 4H-SiC. The results were analyzed with the aid of optical microscope, scanning electron microscope, high-resolution X-ray diffraction and synchrotron white beam X-ray topography. A pronounced effect of the liquid phase epitaxy buffer layer on formation of dislocations and micropipes is observed in the sublimation epitaxy layers. It has been shown that during sublimation growth of epilayer with a thin liquid phase epitaxy buffer layer (0.1µm) defects may undergo transformation and stacking faults can be formed. Sublimation grown epilayers grown on a thick liquid phase epitaxy buffer layer (1µm) also showed a symmetrical distribution of misfit dislocations along the <112¯0> and [11¯00] directions. © 2003 Elsevier B.V. All rights reserved.
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| 15. |
- Jacobson, K., et al.
(författare)
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Chemiluminescence as a tool for polyolefin oxidation studies
- 2004
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Ingår i: Advances in Polymer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 0065-3195 .- 1436-5030. ; 169, s. 151-176
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Forskningsöversikt (refereegranskat)abstract
- The oxidation of polymers such as polypropylene and polyethylene is accompanied by weak chemiluminescence. The development of sensitive photon counting systems has made it comparatively easy to measure faint light emissions and polymer chemiluminescence has become an important method to follow the initial stages in the oxidative degradation of polymers. Alternatively, chemiluminescence is used to determine the amount of hydroperoxides accumulated in a pre-oxidised polymer. Chemiluminescence has also been applied to study how irradiation or mechanical stress affects the rate of polymer oxidation. In recent years, imaging chemiluminescence has been established as a most valuable technique offering both spatial and temporal resolution of oxidation in polymers. This technique has disclosed that oxidation in polyolefins is non-uniformly distributed and proceeds by spreading. This review is the result of several investigations performed by the authors and other research groups where chemiluminescence has been used to study oxidative degradation of polyolefins, either as the main technique or as a complement to other techniques.
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| 18. |
- Persson, Per, et al.
(författare)
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Structural defects in electrically degraded 4H-SiC PiN diodes
- 2002
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Ingår i: Materials Science Forum, Vols. 389-393. ; , s. 423-426
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Konferensbidrag (refereegranskat)abstract
- Triangular structural defects, occasionally generated during long term operation of 4H-SiC pin diodes, are known to negatively affect the forward characteristics of the diode. We have used synchrotron white beam X-ray topography, scanning electron microscopy, in situ cathodo luminescence and transmission electron microscopy for characterizing the structure and formation mechanisms of such defects. It is shown from high-resolution images that the defect results from glide slip on the (0001) basal plane. The defect consists of a stacking fault bound by two partial dislocations with Burgers vectors 1/3<11 (1) over bar0> and 1/3<01 (1) over bar0>. The fault is a means for stress relaxation in the epilayer, near the contact layer using an existing dislocation as a nucleation source.
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