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5 results on '"Kreissig, Ulrich"'

1. Ferromagnetic coupling field reduction in CoFeB tunnel junctions deposited by ion beam

Author

Cardoso, Susana, Ferreira, Ricardo, Freitas, Paulo P., MacKenzie, Maureen, Appleseed, Johnny, Ventura, Joao O., Sousa, Joao B., and Kreissig, Ulrich

Subjects
Electrodes -- Research, Electromagnetism -- Research, Business, Electronics, Electronics and electrical industries
Abstract

In this paper, junctions with reduced [H.sub.f] coupling were fabricated by ion beam deposition and oxidation, using CoFeB electrodes. The CoFeB layer has a strong (111) texture that can be the origin of lower [H.sub.f] and coercivity when compared with CoFe. Junctions processed down to 2 x 4/[micro][m.sup.2] with 40-[Angstrom]-thick CoFeB bottom eiectrodes have 42% of tunneling magnetoresistance (TMR), (R x A ~ 400 [OMEGA]x[micro][m.sup.2]), [H.sub.c] of ~10 Oe and [H.sub.f] of ~2 Oe. CoFe-based junctions (R x A ~ 500 [OMEGA]x[micro][m.sup.2]) have lower TMR (~35%) and larger [H.sub.f] (~5-6 Oe) and [H.sub.c] (~12-14 Oe). Local chemical composition analysis of the cross section indicated Fe-O segregation with very little Co grown on top of the barrier for CoFe-based junctions and not for CoFeB ones. Index Terms--CoFeB electrodes, ion beam deposition, low ferromagnetic coupling, tunnel junctions.

Published
2004

2. Ionendriftprozesse in Borsilikatgläsern während des anodischen Bondens

Author

Nitzsche, Petra, Kreißig, Ulrich, Thomas, Berthold, Huber, Herbert, Schmidt, Bernd, Herzog, Karin, Grigull, Stephan, Assmann, Walter, Lange, Klaus, Nitzsche, Petra, Kreißig, Ulrich, Thomas, Berthold, Huber, Herbert, Schmidt, Bernd, Herzog, Karin, Grigull, Stephan, Assmann, Walter, and Lange, Klaus

Published
2010

3. Overpressurized bubbles versus voids formed in helium implanted annealed silicon

Author

Fichtner, Paulo Fernando Papaleo, Kaschny, Jorge Ricardo de Araujo, Yankov, Rossen A., Mucklich, A., Kreissig, Ulrich, and Skorupa, Wolfgang

Subjects
Física da matéria condensada, Hélio
Abstract

The formation of helium induced cavities in silicon is studied as a function of implant energy (10 and 40 keV) and dose (131015, 131016, and 531016 cm22). Specimens are analyzed after annealing (800 °C, 10 min) by transmission electron microscopy (TEM) and elastic recoil detection (ERD). Cavity nucleation and growth phenomena are discussed in terms of three different regimes depending on the implanted He content. For the low (131015 cm22) and high (531016 cm22) doses our results are consistent with the information in the literature. However, at the medium dose (131016 cm22), contrary to the gas release calculations which predict the formation of empty cavities, ERD analysis shows that a measurable fraction of the implanted He is still present in the annealed samples. In this case TEM analyses reveal that the cavities are surrounded by a strong strain field contrast and dislocation loops are generated. The results obtained are discussed on the basis of an alternative nucleation and growth behavior that allows the formation of bubbles in an overpressurized state irrespective of the competition with the gas release process.

Published
1997

5. Reducing the impurity incorporation from residual gas by ion bombardment during high vacuum magnetron sputtering

Author

Rosén, Johanna, Widenkvist, Erika, Larsson, Karin, Kreissig, Ulrich, Mráz, Stanislav, Martinez, Carlos, Music, Denis, Schneider, J, Rosén, Johanna, Widenkvist, Erika, Larsson, Karin, Kreissig, Ulrich, Mráz, Stanislav, Martinez, Carlos, Music, Denis, and Schneider, J

Abstract

The influence of ion energy on the hydrogen incorporation has been investigated for alumina thin films, deposited by reactive magnetron sputtering in an Ar/O2/H2O environment. Ar+ with an average kinetic energy of ~5 eV was determined to be the dominating species in the plasma. The films were analyzed with x-ray diffraction, x-ray photoelectron spectroscopy, and elastic recoil detection analysis, demonstrating evidence for amorphous films with stoichiometric O/Al ratio. As the substrate bias potential was increased from –15 V (floating potential) to –100 V, the hydrogen content decreased by ~70%, from 9.1 to 2.8 at. %. Based on ab initio calculations, these results may be understood by thermodynamic principles, where a supply of energy enables surface diffusion, H2 formation, and desorption [Rosén et al., J. Phys.: Condens. Matter 17, L137 (2005)]. These findings are of importance for the understanding of the correlation between ion energy and film composition and also show a pathway to reduce impurity incorporation during film growth in a high vacuum ambient.

Published
2006
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