Papers by Author: Björn Magnusson

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Authors: Joakim Eriksson, Niklas Rorsman, Herbert Zirath, Anne Henry, Björn Magnusson, Alexsandre Ellison, Erik Janzén
Authors: Z. Zolnai, Nguyen Tien Son, Björn Magnusson, Christer Hallin, Erik Janzén
Authors: Björn Magnusson, Alexsandre Ellison, F.H.C. Carlsson, Nguyen Tien Son, Erik Janzén
Authors: Peder Bergman, H. Jakobsson, L. Storasta, F.H.C. Carlsson, Björn Magnusson, S.G. Sridhara, G.R. Pozina, H. Lendenmann, Erik Janzén
Authors: Anne Henry, Alexsandre Ellison, Urban Forsberg, Björn Magnusson, G.R. Pozina, Erik Janzén
Authors: Reino Aavikko, Kimmo Saarinen, Björn Magnusson, Erik Janzén
Abstract: Positron annihilation radiation Doppler broadening spectroscopy was used to study defects in semi-insulating (SI) silicon carbide (SiC) substrates grown by high-temperature chemical vapour deposition (HTCVD). The Doppler broadening measurements show (i) that the measured samples contain vacancy clusters (ii) that the positron trapping to the clusters is increased in annealing (iii) that the chemical environment of the defects in the un-annealed samples is different from those of the annealed samples.
Authors: S. Hahn, Franziska Christine Beyer, Andreas Gällström, Patrick Carlsson, Anne Henry, Björn Magnusson, J.R. Niklas, Erik Janzén
Abstract: The novel technique microwave detected photo induced current transient spectroscopy (MD-PICTS) was applied to semi-insulating 6H-SiC in order to investigate the properties of inherent defect levels. Defect spectra can be obtained in the similar way to conventional PICTS and DLTS. However, there is no need for contacting the samples, which allows for non-destructive and spatially resolved electrical characterization. This work is focused on the investigation of semi-insulating 6H-SiC grown under different C/Si-ratios. In the corresponding MD-PICTS spectra several shallow defect levels appear in the low temperature range. However the peak assignment needs further investigation. Additionally different trap reemission dynamics are obtained for higher temperatures, which are supposed to be due to different compensation effects.
Authors: L. Storasta, Björn Magnusson, Anne Henry, Margareta K. Linnarsson, Peder Bergman, Erik Janzén
Authors: Nguyen Tien Son, Patrick Carlsson, Andreas Gällström, Björn Magnusson, Erik Janzén
Abstract: Semi-insulating (SI) 4H-SiC substrates doped with vanadium (V) in the range 5.5×1015 –1.1×1017 cm–3 were studied by electron paramagnetic resonance. We show that only in heavily V-doped 4H-SiC vanadium is responsible for the SI behavior, whereas in moderate V-doped substrates with the V concentration comparable or slightly higher than that of the shallow N donor or B acceptor, the SI properties are thermally unstable and determined by intrinsic defects. The results show that the commonly observed thermal activation energy Ea~1.1 eV in V-doped 4H-SiC, which was previously assigned to the single acceptor V4+/3+ level, may be related to deep levels of the carbon vacancy. Carrier compensation processes involving deep levels of V and intrinsic defects are discussed and possible thermal activation energies are suggested.
Authors: Nguyen Tien Son, Björn Magnusson, Z. Zolnai, Alexsandre Ellison, Erik Janzén
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