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Jensen, Jens
Alternative names
Publications (10 of 44) Show all publications
Intarasiri, S., Dangtip, S., Hallén, A., Jensen, J., Yu, L., Possnert, G. & Singkarat, S. (2007). Activation energy of the growth of ion-beam-synthesized nano-crystalline 3C-SiC. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 257(1-2), 195-198
Open this publication in new window or tab >>Activation energy of the growth of ion-beam-synthesized nano-crystalline 3C-SiC
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2007 (English)In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 257, no 1-2, p. 195-198Article in journal (Refereed) Published
Abstract [en]

In this experiment, carbon ions at 40 keV were implanted into (10 0) high-purity p-type silicon wafers at 400 degrees C to a fluence of 6.5 x 10(17) ions/cm(2). Subsequent thermal annealing of the implanted samples was performed in a vacuum furnace at 800-1000 degrees C. Glancing incidence X-ray diffraction (GIXRD) was used to characterize the crystalline quality and estimate the grain size of nano-crystalline 3C-SiC. Activation energy for the growth of 3C-SiC was evaluated following the annealing behaviour of the GIXRD-characteristic 3C-SiC (111) peaks. It was found that the 3C-SiC was directly formed during ion implantation at this substrate temperature and the activation energy of the process was about 0.05 eV. Such a low energy was explained in terms of ion beam induced precipitate formation.

Keywords
Ion beam synthesis (IBS), Silicon, Silicon carbide (SiC), Glancing incidence X-ray diffraction (GIXRD), Activation energy
National Category
Subatomic Physics Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-11002 (URN)10.1016/j.nimb.2007.01.022 (DOI)000246165500045 ()
Available from: 2007-05-09 Created: 2007-05-09 Last updated: 2017-12-11Bibliographically approved
Skupinski, M., Johansson, A., Jarmar, T., Razpet, A., Hjort, K., Boman, M., . . . Jensen, J. (2007). Carbon nanopillar array deposition on SiO2 by ion irradiation through a porous alumina template. Vacuum, 82(3), 359-362
Open this publication in new window or tab >>Carbon nanopillar array deposition on SiO2 by ion irradiation through a porous alumina template
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2007 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 82, no 3, p. 359-362Article in journal (Refereed) Published
Abstract [en]

A method for producing ordered carbon nanopillar arrays is presented. The method is based on ion irradiation through a small anodic porous alumina membrane, resulting in carbon deposition within the centers of the pores on a gold covered SiO2/Si substrate. Samples were irradiated by 4 MeV Cl2+ ions with fluences of . The combined use of pick’n place positioning of the small porous alumina templates and ion beam irradiation is well suited for post-processing on silicon based integrated circuits. It provides fast local deposition at low temperature of high-density ordered carbon nanopillar arrays in larger silicon based systems, e.g., for field emitting or biosensors applications.

Keywords
SiO2, Carbon nanostructures, Carbon pillars, Ion lithography, Ion irradiation, Anodic porous alumina membrane
National Category
Inorganic Chemistry Subatomic Physics Engineering and Technology
Research subject
Ion Physics
Identifiers
urn:nbn:se:uu:diva-12714 (URN)10.1016/j.vacuum.2007.05.002 (DOI)000251186800009 ()
Available from: 2008-10-06 Created: 2008-10-06 Last updated: 2017-12-11Bibliographically approved
Martin, D., Enlund, J., Kappertz, O. & Jensen, J. (2007). Comparing XPS and ToF-ERDA measurement of high-k dielectric materials. In: : . Paper presented at 17th International Vacuum Conference (IVC-17), 13th International Conference on Surface science (ICSS-13), International Conference on Nanoscience and Technology 2007 (ICN+T 2007) Stockholm, Sweden, July 2-6 (2007) publ in Journal of Physics: Conference Series.
Open this publication in new window or tab >>Comparing XPS and ToF-ERDA measurement of high-k dielectric materials
2007 (English)Conference paper, Published paper (Refereed)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-12732 (URN)
Conference
17th International Vacuum Conference (IVC-17), 13th International Conference on Surface science (ICSS-13), International Conference on Nanoscience and Technology 2007 (ICN+T 2007) Stockholm, Sweden, July 2-6 (2007) publ in Journal of Physics: Conference Series
Available from: 2008-01-11 Created: 2008-01-11 Last updated: 2016-04-11Bibliographically approved
Intarasiri, S., Hallén, A., Lu, J., Jensen, J., Bertilsson, K., Wolborski, M., . . . Possnert, G. (2007). Crystalline quality of 3C-SiC formed by high-fluence C+-implanted Si. Applied Surface Science, 253(11), 4836-4842
Open this publication in new window or tab >>Crystalline quality of 3C-SiC formed by high-fluence C+-implanted Si
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2007 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 11, p. 4836-4842Article in journal (Refereed) Published
Abstract [en]

Carbon ions at 40 keV were implanted into (1 0 0) high-purity p-type silicon wafers at 400 °C to a fluence of 6.5 × 1017 ions/cm2. Subsequent thermal annealing of the implanted samples was performed in a diffusion furnace at atmospheric pressure with inert nitrogen ambient at 1100 °C. Time-of-flight energy elastic recoil detection analysis (ToF-E ERDA) was used to investigate depth distributions of the implanted ions. Infrared transmittance (IR) and Raman scattering measurements were used to characterize the formation of SiC in the implanted Si substrate. X-ray diffraction analysis (XRD) was used to characterize the crystalline quality in the surface layer of the sample. The formation of 3C-SiC and its crystalline structure obtained from the above mentioned techniques was finally confirmed by transmission electron microscopy (TEM). The results show that 3C-SiC is directly formed during implantation, and that the subsequent high-temperature annealing enhances the quality of the poly-crystalline SiC.

Keywords
Ion beam synthesis (IBS), Silicon, Silicon carbide (SiC), Infrared spectroscopy (IR), Raman spectroscopy, Time-of-flight energy elastic recoil detection analysis (ToF-E ERDA), X-ray diffraction (XRD) analysis, Transmission electron microscopy (TEM)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-10998 (URN)10.1016/j.apsusc.2006.10.055 (DOI)000245500200004 ()
Available from: 2007-05-09 Created: 2007-05-09 Last updated: 2017-12-11Bibliographically approved
Intarasiri, S., Yu, L., Singkarat, S., Hallén, A., Lu, J., Ottosson, M., . . . Possnert, G. (2007). Effects of low-fluence swift iodine ion bombardment on the crystallization of ion-beam-synthesized silicon carbide. Journal of Applied Physics, 101(8), 084311
Open this publication in new window or tab >>Effects of low-fluence swift iodine ion bombardment on the crystallization of ion-beam-synthesized silicon carbide
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2007 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 8, p. 084311-Article in journal (Refereed) Published
Abstract [en]

Ion beam synthesis using high-fluence carbon ion implantation in silicon in combination with subsequent or in situ thermal annealing has been shown to be able to form nanocrystalline cubic SiC (3C-SiC) layers in silicon. In this study, a silicon carbide layer was synthesized by 40-keV C 12 + implantation of a p -type (100) Si wafer at a fluence of 6.5× 1017 ions cm2 at an elevated temperature. The existence of the implanted carbon in Si substrate was investigated by time-of-flight energy elastic recoil detection analysis. The SiC layer was subsequently irradiated by 10-30 MeV I 127 ions to a very low fluence of 1012 ions cm2 at temperatures from 80 to 800 °C to study the effect on the crystallization of the SiC layer. Infrared spectroscopy and Raman scattering measurement were used to monitor the formation of SiC and detailed information about the SiC film properties was obtained by analyzing the peak shape of the Si-C stretching mode absorption. The change in crystallinity of the synthesized layer was probed by glancing incidence x-ray diffraction measurement and transmission electron microscopy was also used to confirm the results and to model the crystallization process. The results from all these measurements showed in a coherent way that the synthesized structure was a polycrystalline layer with nanometer sized SiC crystals buried in a-Si matrix. The crystallinity of the SiC layer was enhanced by the low-fluence swift heavy ion bombardment and also favored by higher energy, higher fluence, and higher substrate temperature. It is suggested that electronic stopping plays a dominant role in the enhancement.

Keywords
silicon compounds, wide band gap semiconductors, semiconductor thin films, crystallisation, ion beam effects, ion implantation, infrared spectra, Raman spectra, crystal structure, X-ray diffraction, transmission electron microscopy, nanostructured materials, electron energy loss spectra, Rutherford backscattering, annealing
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-11000 (URN)10.1063/1.2720090 (DOI)000246072200135 ()
Available from: 2008-09-30 Created: 2008-09-30 Last updated: 2017-12-11Bibliographically approved
Sanz, R., Jaafar, M., Rosa, W., Badini-Confalonieri, G., Jensen, J., Hernandez-Vélez, M. & Vázquez, M. (2007). Effects on the structural and magnetic properties of amorphous ribbons of (Co0.94Fe0.06)(72.5)Si12.5B15 caused by 4 MeV Cl2+ ion irradiation. Journal of Non-Crystalline Solids, 353(8-10), 879-882
Open this publication in new window or tab >>Effects on the structural and magnetic properties of amorphous ribbons of (Co0.94Fe0.06)(72.5)Si12.5B15 caused by 4 MeV Cl2+ ion irradiation
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2007 (English)In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 353, no 8-10, p. 879-882Article in journal (Refereed) Published
Abstract [en]

The use of energetic ion irradiation to modify magnetic materials has attracted increasing interest in recent years. The possibility of patterning surfaces on these materials offers a wide range of potential applications particularly in technologies related to magnetic storage media, sensing devices and electromagnetic shielding materials. In this work, ultrasoft non-magnetostrictive (Co0.94Fe0.06)72.5Si12.5B15 amorphous ribbons, 50 μm thick and 0.85 mm wide, fabricated by the chilly block melt spinning technique are irradiated, in their amorphous state, by 4 MeV Cl2+ ions with a fluence of 5 × 1013 cm-2. The hysteresis properties of both irradiated and non-irradiated samples are characterized by means of a vibrating sample magnetometer while surface magnetic domain structure is observed by Bitter technique. The presence of an induced magnetic anisotropy in irradiated samples is ascribed to the local damage, caused by ion irradiation treatment, which results in modified coercive field and permeability of the samples. X-ray diffraction results are presented to confirm the amorphicity of the structure even after irradiation with ions.

Keywords
Alloys, Magnetic properties, Mechanical, stress relaxation, Radiation
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-11001 (URN)10.1016/j.jnoncrysol.2006.12.070 (DOI)000245795800045 ()
Available from: 2007-05-09 Created: 2007-05-09 Last updated: 2017-12-11Bibliographically approved
Zettergren, H., Schmidt, H. T., Cederquist, H., Jensen, J., Hvelplund, P., Tomita, S., . . . Huber, B. (2007). Even-odd effects in the ionization cross sections of [C60]2 and [C60C70] dimers. Physical Review A. Atomic, Molecular, and Optical Physics, 75(5), 051201
Open this publication in new window or tab >>Even-odd effects in the ionization cross sections of [C60]2 and [C60C70] dimers
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2007 (English)In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 75, no 5, p. 051201-Article in journal (Refereed) Published
Abstract [en]

We report strong even-odd effects in multiple ionization yields of van der Waals dimers in slowXe30+ + ͓C60͔2͓͑C60C70͔͒ →  ̄ + ͓C60͔2r+͓͑C60C70͔r+͒ electron-transfer collisions as functions of r Յ 7. Thisbehavior may be due to even-odd variations in the sequences of dimer ionization energies as calculated with anelectrostatic model including an electrical fullerene-fullerene contact at the 19a0 center-center separation in͓C60͔2+. Prompt dissociations predominantly yield intact fullerenes ͓C60͔2r+ → C60r1+ + C60r2+ in the same͑r1 = r2, even r͒ or nearby ͑r1 = r2 ± 1, odd r Ͼ 1͒ charge states.

Keywords
fullerenes, quasimolecules, charge exchange, ion-molecule collisions, ionisation, dissociation
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-12709 (URN)10.1103/PhysRevA.75.051201 (DOI)000246890400009 ()
Available from: 2008-01-10 Created: 2008-01-10 Last updated: 2017-12-11Bibliographically approved
Snyders, R., Music, D., Sigumonrong, D., Schelnberger, B., Jensen, J. & Schneider, J. (2007). Experimental and ab initio study of the mechanical properties of hydroxyapatite. Applied Physics Letters, 90(19), 193902
Open this publication in new window or tab >>Experimental and ab initio study of the mechanical properties of hydroxyapatite
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2007 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 90, no 19, p. 193902-Article in journal (Refereed) Published
Abstract [en]

The authors have studied the elastic properties of radio frequency sputtered phase pure, stoichiometric, and dense hydroxyapatite films by nanoindentation. The measured elastic modulus values have been compared to ab initio calculated data. The calculation technique was based on the determination of all elastic constants. The calculated and measured elastic modulus values differ by ∼10%. The good agreement indicates that the elasticity of hydroxyapatite can be described using ab initio calculations, establishing the elastic modulus thereof.

Keywords
calcium compounds, thin films, ab initio calculations, elasticity, indentation, elastic moduli
National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-12707 (URN)10.1063/1.2738386 (DOI)000246413400102 ()
Available from: 2008-06-09 Created: 2008-06-09 Last updated: 2017-12-11Bibliographically approved
Jaafar, M., Sanz, R., Vazquez, M., Asenjo, A., Jensen, J., Hjort, K., . . . Schäfer, R. (2007). FePt thin film irradiated with high energy ions. Physica status solidi. A, Applied research, 204(6), 1724-1730
Open this publication in new window or tab >>FePt thin film irradiated with high energy ions
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2007 (English)In: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 204, no 6, p. 1724-1730Article in journal (Refereed) Published
Abstract [en]

The changes in structural and magnetic properties of FePt thin films due to the irradiation with high energy ions (Br7+ and Cl2+) were studied. From the hysteresis loops dominating in-plane anisotropy is derived, however, the samples present a minor out-of-plane component. The structure and the magnetic properties of the films can be tuned by selecting the appropriate irradiation parameters (different ions, energies and fluencies). For the irradiation parameters used in this study an in-plane anisotropy is favoured. Irradiation with Br7+ seems to induce minor changes in the structural ordering of the thin films, whereas the Cl2+ ions promote the amorphization of the surface of the films. In addition, a magnetic thin film pattemed at the micrometer scale was obtained after irradiation through a micrometric mask.

Keywords
61.80.Jh, 68.37.Rt, 68.55.Jk, 75.60.-d
National Category
Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-12715 (URN)10.1002/pssa.200675342 (DOI)000247542500018 ()
Available from: 2008-01-10 Created: 2008-01-10 Last updated: 2017-12-11Bibliographically approved
Skupiński, M., Jensen, J., Johansson, A., Possnert, G., Boman, M., Hjort, K. & Razpet, A. (2007). Nanopattern transfer to SiO2 by ion track lithography and highly selective HF vapor etching. Journal of Vacuum Science & Technology B, 25(3), 862-867
Open this publication in new window or tab >>Nanopattern transfer to SiO2 by ion track lithography and highly selective HF vapor etching
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2007 (English)In: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 25, no 3, p. 862-867Article in journal (Refereed) Published
Abstract [en]

The authors present a method for high aspect ratio nanopatterning of high density (1010  pores/cm2) self-assembled porous alumina membrane pattern into thermally grown SiO2 on silicon. The pattern transfer is accomplished by irradiating through 2  µm thick porous alumina membrane with swift heavy ions (4  MeV Cl2+). Ions passing through the nanopores in the mask at a fairly high fluence (typically 1014  ions/cm2) are impinging on the substrate and creating a continuous volume of overlapping ion tracks of damage. The damage is sufficient to be selectively etched by HF vapor from an aqueous HF solution. From an alumina mask with pores of 70  nm diameter, a pattern of pores of 77  nm in diameter and the same distance of 100  nm between the centers of the pores was transferred. The deepest observed etched pores were 355  nm, giving an aspect ratio of 5, which is up to 40 times larger compare to earlier work where HF wet etching was used. This ion track lithography technique shows a potential to produce nanostructures with even higher aspect ratios.

Keywords
silicon compounds, nanopatterning, nanolithography, ion beam effects, etching, masks, resists, porosity, nanoporous materials
National Category
Engineering and Technology Physical Sciences
Identifiers
urn:nbn:se:uu:diva-94957 (URN)10.1116/1.2738481 (DOI)000247551300033 ()
Available from: 2006-10-13 Created: 2006-10-13 Last updated: 2017-12-14Bibliographically approved
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