| 1. |
- Hallén, Anders., et al.
(författare)
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Ion implantation of silicon carbide
- 2002
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - 0168-583X .- 1872-9584. ; 186, s. 186-194
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Tidskriftsartikel (refereegranskat)abstract
- Ion implantation is an important technique for a successful implementation of commercial SiC devices. Much effort has also been devoted to optimising implantation and annealing parameters to improve the electrical device characteristics. However, there is a severe lack of understanding of the fundamental implantation process and the generation and annealing kinetics of point defects and defect complexes. Only very few of the most elementary intrinsic point defects have been unambiguously identified so far. To reach a deeper understanding of the basic mechanisms SiC samples have been implanted with a broad range of ions, energies, doses, etc., and the resulting defects and damage produced in the lattice have been studied with a multitude of characterisation techniques. In this contribution we will review some of the results generated recently and also try to indicate where more research is needed. In particular, deep level transient spectroscopy (DLTS) has been used to investigate point defects at very low doses and transmission electron microscopy (TEM) and Rutherford backscattering spectrometry (RBS) are used for studying the damage build-up at high doses.
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| 2. |
- Persson, Asa E, et al.
(författare)
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The mutagenic effect of ultraviolet-A1 on human skin demonstrated by sequencing the p53 gene in single keratinocytes.
- 2002
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Ingår i: Photodermatology, Photoimmunology & Photomedicine. - : Wiley. - 0905-4383 .- 1600-0781. ; 18:6, s. 287-293
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Sun exposure is accepted as the major risk factor for developing skin cancer, the most common cancer in the western world. Ultraviolet-B (UV-B) radiation is considered the causative agent, but recently several findings suggest a role also for ultraviolet-A (UV-A) radiation. Repeated suberythemal doses of ultraviolet-A1 (UV-A1) on healthy human skin induce an increase of p53 immunoreactive cells in epidermis, which may indicate cell cycle arrest and/or occurrence of p53 mutations.METHODS: We have investigated the possible mutagenic effect of UV-A1 on skin by sequencing exons 4-11 and adjacent intron sequence of the p53 gene in immunoreactive single cells from three healthy individuals. Previously unexposed buttock skin was irradiated three times a week for 2 weeks with physiological fluences (40 J/cm2) of UV-A1. Punch biopsies were taken before and at different time-points after the exposure, and from these single p53 immunoreactive cells were isolated by using laser-assisted microdissection.RESULTS: Three mutations--all being indicative of oxidative damage and most likely related to UV-A exposure--were found among the 37 single cells from exposed skin, whereas no mutations were found in the 22 single cells taken before exposure.CONCLUSIONS: The findings indicate a mutagenic effect of low-dose UV-A1 on healthy human skin, which further demonstrates the importance of considering UV-A when taking protective measures against skin cancer.
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| 3. |
- Persson, Fredrik, et al.
(författare)
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A QoS parameters translater
- 2003
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Patent (populärvet., debatt m.m.)abstract
- When UMTS is part of IP end-to-end communication, there must exist means for UMTS to be able to provide the required Quality of Service (QoS) for applications running over IP. Hence there is a need for a translation function for translation between IP QoS parameters and UMTS QoS attributes. This translation is not trivial because of several reasons. First, the number of QoS parameters in the IP level and the UMTS level are different. Second, definitions of parameters at the two levels are different. Keeping these factors in view, the present invention provides for a method for translation of IP QoS parameters to UMTS QoS attributes, and another method for translation of UMTS QoS attributes to IP QoS parameters. This translation will enable spectrum efficient UMTS bearers to be set up for applications running over IP. This will also make negotiation of services possible between an entity at the IP level and the UMTS network. These methods are placed in both the User Equipment as well as the Gateway of the UMTS network.
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| 4. |
- Svensson, BG, et al.
(författare)
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Doping of silicon carbide by ion implantation
- 2001
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Ingår i: Materials Science Forum, Vols. 353-356. - : Trans Tech Publications Inc.. - 9780878498734 - 0878498737 ; , s. 549-554, s. 549-554
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Konferensbidrag (refereegranskat)abstract
- A brief survey is given of some recent results on doping of 4H- and 6H-SiC by ion implantation. The doses and energies used are between 10(9) and 10(15) cm(-2) and 100 keV and 5 MeV, respectively, and B and Al ions (p-type dopants) are predominantly studied. After low dose implantation (less than or equal to 10(10) cm(-2)) a strong compensation is observed in n-type samples and this holds irrespective of implantation temperature up to 600 degreesC. However, at higher doses (10(14)-10(15) Al/cm(2)) the rate of defect recombination (annihilation) increases substantially during hot implants (greater than or equal to 200 degreesC) and in these samples one type of structural defect dominates after past-implant annealing at 1700-2000 degreesC. The defect is identified as a dislocation loop composed of clustered interstitial atoms inserted on the basal plane in the hexagonal crystal structure. Finally, transient enhanced diffusion (TED) of ion-implanted boron in 4H-samples is discussed.
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