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  • 1.
    Ahuja, Rajeev
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Arwin, H.
    Ferreira da Silva, A.
    Persson, C.
    Osorio-Guillén, J. M.
    Souza de Almeida, J.
    Araujo, C. Moyses
    Veje, E.
    Veissid, N.
    An, C. Y.
    Electronic and optical properties of lead iodide2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 92, p. 7219-Article in journal (Refereed)
    Abstract [en]

    The electronic properties and the optical absorption of lead iodide (PbI2) have been investigated experimentally by means of optical absorption and spectroscopic ellipsometry, and theoretically by a full-potential linear muffin-tin-orbital method. PbI2 has been recognized as a very promising detector material with a large technological applicability. Its band-gap energy as a function of temperature has also been measured by optical absorption. The temperature dependence has been fitted by two different relations, and a discussion of these fittings is given.

  • 2. Aiempanakit, Montri
    et al.
    Aijaz, Asim
    Lundin, Daniel
    Helmersson, Ulf
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Understanding the discharge current behavior in reactive high power impulse magnetron sputtering of oxides2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 13, p. 133302-Article in journal (Refereed)
    Abstract [en]

    The discharge current behavior in reactive high power impulse magnetron sputtering (HiPIMS) of Ti-O and Al-O is investigated. It is found that for both metals, the discharge peak current significantly increases in the oxide mode in contrast to the behavior in reactive direct current magnetron sputtering where the discharge current increases for Al but decreases for Ti when oxygen is introduced. In order to investigate the increase in the discharge current in HiPIMS-mode, the ionic contribution of the discharge in the oxide and metal mode is measured using time-resolved mass spectrometry. The energy distributions and time evolution are investigated during the pulse-on time as well as in the post-discharge. In the oxide mode, the discharge is dominated by ionized oxygen, which has been preferentially sputtered from the target surface. The ionized oxygen determines the discharge behavior in reactive HiPIMS.

  • 3. Ali, MP
    et al.
    Tove, PA
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ibrahim, M
    Barrier height of evaporated manganese contacts to silicon1979In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 50, no 11, p. 7250-Article in journal (Refereed)
  • 4. Alkhadi, H.S.
    et al.
    Tran, Tuan
    Department of Electronic Materials Engineering, Research School of Physics and Engineering, The Australian National University, Canberra, Australia.
    Kremer, F.
    Williams, J.S.
    The influence of capping layers on pore formation in Ge during ion implantation2016In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 120, no 21, article id 215706Article in journal (Refereed)
    Abstract [en]

    Ion induced porosity in Ge has been investigated with and without a cap layer for two ion species, Ge and Sn, with respect to ion fluence and temperature. Results without a cap are consistent with a previous work in terms of an observed ion fluence and temperature dependence of porosity, but with a clear ion species effect where heavier Sn ions induce porosity at lower temperature (and fluence) than Ge. The effect of a cap layer is to suppress porosity for both Sn and Ge at lower temperatures but in different temperatures and fluence regimes. At room temperature, a cap does not suppress porosity and results in a more organised pore structure under conditions where sputtering of the underlying Ge does not occur. Finally, we observed an interesting effect in which a barrier layer of a-Ge that is denuded of pores formed directly below the cap layer. The thickness of this layer (∼ 8 nm) is largely independent of ion species, fluence, temperature, and cap material, and we suggest that this is due to viscous flow of a-Ge under ion irradiation and wetting of the cap layer to minimize the interfacial free energy.

  • 5. Al-Zoubi, N.
    et al.
    Johansson, Börje
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Nilson, G.
    Vitos, Levente
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    The Bain path of paramagnetic Fe-Cr based alloys2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, no 1, p. 013708-Article in journal (Refereed)
    Abstract [en]

    Employing the first-principles exact muffin-tin orbital method in combination with the coherent potential approximation, we calculated the total energy and local magnetic moments of paramagnetic Fe-Cr-M (M = Cr, Mn, Fe, Co, Ni) alloys along the tetragonal distortion (Bain) path connecting the body centered cubic (bcc) and the face centered cubic (fcc) structures. The paramagnetic phase is modeled by the disordered local magnetic moment scheme. For all alloys, the local magnetic moments on Fe atoms decrease from the maximum value corresponding to the bcc phase toward the minimum value realized for the fcc phase. Cobalt atoms have non-vanishing local magnetic moments only for tetragonal lattices with c/a < 1.30, whereas the local magnetic moments of Mn show weak crystal structure dependence. We find that Cr stabilizes the bcc lattice and increases the energy barrier as going from the bcc toward the fcc phase. Both Co and Ni favor the fcc lattice and decrease the energy barrier relative to the bcc phase. On the other hand, the tetragonal distortion around the fcc phase is facilitated by Cr and to a somewhat lesser extent also by Ni, but strongly impeded by Co. Manganese has negligible effect on the structural energy difference as well as on the energy barrier along the Bain path. Our findings on the alloying induced softening or hardening of Fe-Cr based alloys against tetragonal distortions are important for understanding the interstitial driven martensitic transformations in alloy steels.

  • 6.
    Araujo, Rafael B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    de Almeida, J. S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    da Silva, A. Ferreira
    Univ Fed Bahia, Inst Fis, Salvador, BA, Brazil..
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Insights in the electronic structure and redox reaction energy in LiFePO4 battery material from an accurate Tran-Blaha modified Becke Johnson potential2015In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 118, no 12, article id 125107Article in journal (Refereed)
    Abstract [en]

    The main goals of this paper are to investigate the accuracy of the Tran-Blaha modified Becke Johnson (TB-mBJ) potential to predict the electronic structure of lithium iron phosphate and the related redox reaction energy with the lithium deintercalation process. The computed electronic structures show that the TB-mBJ method is able to partially localize Fe-3d electrons in LiFePO4 and FePO4 which usually is a problem for the generalized gradient approximation (GGA) due to the self interaction error. The energy band gap is also improved by the TB-mBJ calculations in comparison with the GGA results. It turned out, however, that the redox reaction energy evaluated by the TB-mBJ technique is not in good agreement with the measured one. It is speculated that this disagreement in the computed redox energy and the experimental value is due to the lack of a formal expression to evaluate the exchange and correlation energy. Therefore, the TB-mBJ is an efficient method to improve the prediction of the electronic structures coming form the standard GGA functional in LiFePO4 and FePO4. However, it does not appear to have the same efficiency for evaluating the redox reaction energies for the investigated system.

  • 7.
    Aydin, Alhun
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Fransson, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sisman, Altug
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Thermosize voltage induced in a ballistic graphene nanoribbon junction2019In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 126, article id 104302Article in journal (Refereed)
    Abstract [en]

    A thermoelectric voltage is induced in a junction, constituted of two dissimilar materials under a temperature gradient. Similarly, a thermosize voltage is expected to be induced in a junction made by the same material but having differentsizes, so-called thermosize junction. This is a consequence of dissimilarity in Seebeck coefficients due to differencesin classical and/or quantum size effects in the same materials with different sizes. The studies on thermosize effectsin literature are mainly based on semi-classical models under relaxation time approximation or even simpler localequilibrium ones where only very general ideas and results have been discussed without considering quantum transport approaches and specific materials. To make more realistic predictions for a possible experimental verification, here,we consider ballistic thermosize junctions made by narrow and wide (n-w) pristine graphene nanoribbons with perfectarmchair edges and calculate the electronic contribution to the thermosize voltage, at room temperature, by using the Landauer formalism. The results show that the maximum thermosize voltage can be achieved for semiconducting nanoribbons and it is about an order of magnitude larger than that of metallic nanoribbons. In the semiconducting case, the thermosize voltage forms a characteristic plateau for a finite range of gating conditions. We demonstrate, throughnumerical calculations, that the induced thermosize voltage per temperature difference can be in the scale of mV/K,which is high enough for experimental measurements. Owing to their high and persistent thermosize voltage values,graphene nanoribbons are expected to be good candidate for device applications of thermosize effects.

  • 8. Azarov, A. Yu.
    et al.
    Jensen, Jens
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Hallen, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Ion Physics.
    Aggerstam, T.
    Dopant distribution in high fluence Fe implanted GaN2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 104, no 5, p. 053509-Article in journal (Refereed)
    Abstract [en]

    Undoped wurtzite GaN epilayers implanted at room temperature with 50-325 keV Fe+ ions in the fluence range of 10(15)-10(17) ions/cm(2) are studied by a combination of Rutherford backscattering/channeling spectrometry and time-of-flight elastic recoil detection analysis. The results show an enhanced Fe concentration close to the surface for high ion fluences (>1 X 10(16) cm(-2)), which increases with the ion fluence. Annealing at 800 degrees C for 30 min has a negligible effect on the Fe distribution in the material bulk, but further increases the Fe concentration near the surface. Our findings can be understood by radiation enhanced diffusion during ion implantation and an increased Fe diffusivity in the near surface region with distorted stoichiometry, or formation of secondary phases and precipitates for the highest doses. The simulation shows that, if enhanced diffusion is the reason for Fe buildup at the surface, both radiation enhanced diffusion and the thermal diffusion of Fe atoms near the surface, need to be at least five times larger than ordinary bulk diffusion to explain the increased Fe surface concentration.

  • 9.
    Backholm, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Georén, Peter
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Determination of solid phase chemical diffusion coefficient and density of states by electrochemical methods: Application to iridium oxide-based thin films2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 103, no 2, p. 023702-Article in journal (Refereed)
    Abstract [en]

    Potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS) were investigated as methods to determine solid phase chemical diffusion coefficient (D) and electronic density of states (DOS). These techniques were then applied to iridium oxide (IrOx) and iridium-tantalum oxide (IrTaOx) thin films prepared by sputter deposition. The experiments, performed in 1M propionic acid between -0.2 and 0.8 V vs Ag/AgCl, showed effects of interfacial side reactions, whose contribution to the electrochemical response could be identified and corrected for in the case of PITT as well as EIS. It was found that D is strongly underestimated when using PITT with the common Cottrell formalism, which follows from non-negligible interfacial charge transfer and Ohmic resistances. EIS indicated an anomalous diffusion mechanism, and D was determined to be in the 10(-11)-10(-10) cm(2)/s range for IrOx and IrTaOx. Both PITT and EIS showed that the intercalated charge as a function of potential exhibits a shape that resembles the theoretical DOS of crystalline iridium oxide, especially for IrTaOx.

  • 10. Baglin, J
    et al.
    d'Heurle, F
    Petersson, CS
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Diffusion marker experiments with rare-earth silicides and germanides: relative mobilities of the two atom species1981In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 52Article in journal (Refereed)
  • 11. Balmer, Richard S.
    et al.
    Friel, Ian
    Hepplestone, Steven
    Isberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Uren, Michael J.
    Markham, Matthew L.
    Palmer, Nicola L.
    Pilkington, James
    Huggett, Paul
    Majdi, Saman
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Lang, Richard
    Transport behavior of holes in boron delta-doped diamond structures2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 3, p. 033702-Article in journal (Refereed)
    Abstract [en]

    Boron delta-doped diamond structures have been synthesized using microwave plasma chemical vapor deposition and fabricated into FET and gated Hall bar devices for assessment of the electrical characteristics. A detailed study of variable temperature Hall, conductivity, and field-effect mobility measurements was completed. This was supported by Schrodinger-Poisson and relaxation time calculations based upon application of Fermi's golden rule. A two carrier-type model was developed with an activation energy of similar to 0.2 eV between the delta layer lowest subband with mobility similar to 1 cm(2)/Vs and the bulk valence band with high mobility. This new understanding of the transport of holes in such boron delta-doped structures has shown that although Hall mobility as high as 900 cm(2)/Vs was measured at room temperature, this dramatically overstates the actual useful performance of the device.

  • 12.
    Barwal, Vineet
    et al.
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Husain, Sajid
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Behera, Nilamani
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Goyat, Ekta
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Chaudhary, Sujeet
    Indian Inst Technol Delhi, Dept Phys, Thin Film Lab, New Delhi 110016, India..
    Growth dependent magnetization reversal in Co2MnAl full Heusler alloy thin films2018In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 123, no 5, article id 053901Article in journal (Refereed)
    Abstract [en]

    Angular dependent magnetization reversal has been investigated in Co2MnAl (CMA) full Heusler alloy thin films grown on Si(100) at different growth temperatures (T-s) by DC-magnetron sputtering. An M-shaped curve is observed in the in-plane angular (0 degrees-360 degrees) dependent coercivity (ADC) by magneto-optical Kerr effect measurements. The dependence of the magnetization reversal on Ts is investigated in detail to bring out the structure-property correlation with regards to ADC in these polycrystalline CMA thin films. This magnetization reversal (M-shaped ADC behavior) is well described by the two-phase model, which is a combination of Kondorsky (domain wall motion) and Stoner Wohlfarth (coherent rotation) models. In this model, magnetization reversal starts with depinning of domain walls, with their gradual displacement explained by the Kondorsky model, and at a higher field (when the domain walls merge), the system follows coherent rotation before reaching its saturation following the Stoner Wohlfarth model. Further, the analysis of angular dependent squareness ratio (M-r/M-s) indicates that our films clearly exhibited twofold uniaxial anisotropy, which is related to self-steering effect arising due to the obliquely incident flux during the film-growth.

  • 13.
    Battiato, Marco
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Maldonado, Pablo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Oppeneer, Peter M.
    Treating the effect of interface reflections on superdiffusive spin transport in multilayer samples (invited)2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, no 17, p. 172611-Article in journal (Refereed)
    Abstract [en]

    Femtosecond laser-induced magnetization dynamics has recently been related to superdiffusive spin transport. With the aim to accurately compute spin superdiffusion in the complex geometries of layered heterostructures and free standing layers, we develop here a dedicated numerical scheme. We introduce a discretization technique to solve the superdiffusive equation numerically on a time and space grid. The discretization scheme facilitates an explicit treatment of the total reflection at the vacuum-material surfaces as well as of partial reflections at the interfaces between two different materials. The advantages of the numerical technique are discussed. (C) 2014 AIP Publishing LLC.

  • 14.
    Berg, Sören
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Larsson, T
    Nender, C
    Blom, Hans-Olof
    Predicting thin film stoichiometry in reactive sputtering1988In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 63, no 3, p. 887-Article in journal (Refereed)
  • 15.
    Berggren, Lars
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Azens, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Polaron Absorption in Amorphous Tungsten Oxide Films2001In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 90, p. 1860-1863Article in journal (Refereed)
    Abstract [en]

    Amorphous thin films of tungsten oxide were deposited by sputtering onto glass substrates covered by conductive indium–tin oxide. The density and stoichiometry were determined by Rutherford backscattering spectrometry. Lithium ions were intercalated electrochemically into the films. The optical reflectance and transmittance were measured in the wavelength range from 0.3 to 2.5 μm, at a number of intercalation levels. The polaron absorption peak becomes more symmetric and shifts to higher energies until an intercalation level of 0.25 to 0.3 Li+/W, where a saturation occurs. The shape of the polaron peak is in very good agreement with the theory of Bryksin [Fiz. Tverd. Tela 24, 1110 (1982)]. Within this model, the shift of the absorption peak is interpreted as an increase in the Fermi level of the material as more Li ions are inserted.

  • 16.
    Berggren, Lars
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Jonsson, Jacob C.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Optical absorption in lithiated tungsten oxide thin films: Experiment and theory2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 102, no 8, p. 083538-Article in journal (Refereed)
    Abstract [en]

    Amorphous tungsten oxide exhibits electrochromism when intercalated with protons, lithium, sodium, and other ions. Thin films of the material were prepared by dc magnetron sputtering and then electrochemically intercalated with lithium. The optical absorption in the wavelength range of 300-2500 nm was measured for a number of lithium concentrations. The optical absorption shows a maximum for lithium/tungsten ratios of 0.3-0.5. The optical spectra can be fitted by a superposition of three Gaussian peaks, representing the three possible electronic transitions between W6+, W5+, and W4+ sites. The variation of the peak strength with lithium concentration is consistent with an extended site-saturation theory.

  • 17.
    Berglund, Martin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Thornell, Greger
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Persson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Microsystems Technology.
    Microplasma source for optogalvanic spectroscopy of nanogram samples2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 114, no 3, p. 033302-Article in journal (Refereed)
    Abstract [en]

    The demand for analysis of smaller samples in isotopic ratio measurements of rare isotopes is continuously rising with the development of new applications, particularly in biomedicine. Interesting in this aspect are methods based on optogalvanic spectroscopy, which have been reported to facilitate both 13C-to-12C and 14C-to-12C ratio measurements with high sensitivity. These methods also facilitate analysis of very small samples, down to the microgram range, which makes them very competitive to other technologies, e.g., accelerator mass spectroscopy. However, there exists a demand for moving beyond the microgram range, especially from regenerative medicine, where samples consist of, e.g., DNA, and, hence, the total sample amount is extremely small. Making optogalvanic spectroscopy of carbon isotopes applicable to such small samples, requires miniaturization of the key component of the system, namely the plasma source, in which the sample is ionized before analysis. In this paper, a novel design of such a microplasma source based on a stripline split-ring resonator is presented and evaluated in a basic optogalvanic spectrometer. The investigations focus on the capability of the plasma source to measure the optogalvanic signal in general, and the effect of different system and device specific parameters on the amplitude and stability of the optogalvanic signal in particular. Different sources of noise and instabilities are identified, and methods of mitigating these issues are discussed. Finally, the ability of the cell to handle analysis of samples down to the nanogram range is investigated, pinpointing the great prospects of stripline split-ring resonators in optogalvanic spectroscopy.

  • 18.
    Bohlin, KE
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Generalized Norde plot including determination of the ideality factor1986In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 60, no 3Article in journal (Refereed)
  • 19.
    Bottger, P. H. M.
    et al.
    Laboratory of Nanoscale Materials Science, EMPA, Dübendorf, Switzerland .
    Braginsky, L.
    Laboratory of Crystallography, ETH Zürich, Zürich, Switzerland.
    Shklover, V.
    Laboratory of Crystallography, ETH Zürich, Zürich, Switzerland.
    Lewin, Erik
    Laboratory of Nanoscale Materials Science, EMPA, Dübendorf, Switzerland .
    Patscheider, J.
    Laboratory of Nanoscale Materials Science, EMPA, Dübendorf, Switzerland .
    Cahill, D. G.
    Department of Materials Science and Engineering, University of Illinois, Urbana, Illinois, USA .
    Sobiech, M.
    Oerlikon Balzers Coating AG, Balzers, Principality of Liechtenstein .
    Hard wear-resistant coatings with anisotropic thermal conductivity for high thermal load applications2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 1, p. 013507-Article in journal (Refereed)
    Abstract [en]

    High thermal load applications such as high speed dry cutting lead to high temperatures in the coated tool substrate that can soften the tool and high temperature gradients that can put stress on the coating/tool interface. In this work, theoretical considerations are presented for multilayer and graded protective coatings that can induce a significant anisotropy in their thermal conductivity. Solution of the heat equation shows that anisotropy of thermal conductivity has the potential to reduce temperatures and temperature gradients arising due to brief, localized heat at the coating surface ("hot-spots"). Experimental realization of high anisotropy is demonstrated in TiN/AlCrN multilayer coatings with variable layer thickness. In the coating with 50 nm bilayer periodicity, the highest anisotropy was obtained with a value of kappa(parallel to)/kappa(perpendicular to) = 3.0 +/- 0.9. Time-domain thermoreflectance is used to measure in-plane and cross-plane thermal conductivity of fabricated coatings. The observed high values of anisotropy of thermal conductivity are compared with theoretical predictions and its realisation is discussed with regard to the coating microstructure.

  • 20.
    Brena, Barbara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Herper, Heike C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Influence of ligands on the electronic and magnetic properties of Fe porphyrin in gas phase and on Cu(001)2015In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 117, no 17, article id 17B318Article in journal (Refereed)
    Abstract [en]

    A study of the adsorption of different axial ligands on Fe porphyrin (FeP), both isolated and adsorbed on Cu(001), was performed by means of Density Functional Theory. The electronic and magnetic properties of the adsorbed FeP resulted to be strongly influenced by the axial ligands considered, Cl and O. Cl induces an enhancement of the overall molecular magnetic moment of 3.0 mu(B) while O or O-2 leave the spin state of the molecule unchanged. The influence of the Cl in the electronic states was moreover studied by means of theoretical NEXAFS N K-edge, where the spectra of isolated FeP and FeP with Cl ligand were calculated. The adsorption of the FeP molecules on Cu(001) leads in case of Cl to a further increase of the magnetic moment due to strong deformation of the Fe-N bond.

  • 21.
    Broddefalk, A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Granberg, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Liu, HP
    Andersson, Y
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Magnetocrystalline anisotropy of (Fe1-xCox)(3)P1998In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 83, no 11, p. 6980-6982Article in journal (Other academic)
    Abstract [en]

    The magnetocrystalline anisotropy energy (MAE) of (Fe1-xCox)(3)P (x = 0, 0.1, 0.2, 0.33) has been studied in the temperature range 5 K-300 K. The compound crystallizes in a tetragonal structure with three non-equivalent metal sites and shows an easy plan

  • 22.
    Bručas, Rimantas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Chalmers tekniska högskola.
    Hanson, M.
    Chalmers tekniska högskola.
    Gunnarsson, R.
    Chalmers tekniska högskola.
    Wahlström, E.
    van Kampen, Maarten
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Lidbaum, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Experimental Physics.
    Leifer, Klaus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Magnetic and transport properties of Ni81Fe19/Al2O3 granular multilayers approaching the superparamagnetic limit2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 7, p. 073907-Article in journal (Refereed)
    Abstract [en]

    The magnetic and transport properties of Ni81Fe 19/Al2O3 granular multilayer films were studied in relation to their structural properties as the nominal thickness t of the permalloy (Ni81Fe19) layer was varied near the percolation limit: in the range of 8≤t≤ 16 Å while keeping the nominal thickness of the Al2O3 layers constant at 16 Å. A good structural quality of the multilayers was demonstrated by low angle x-ray reflectivity measurements, and transmission electron microscopy showed the transition from continuous permalloy layers separated by aluminium oxide layers for t= 16 Å to metal grains dispersed in the insulator at t=8 Å. Magnetization measurements showed the gradual transition from ferromagnetic layers to superparamagnetic clusters and grains that successively become blocked as the temperature decreases. A strong correlation between transport and structural properties was observed in the temperature (T) dependence of the electrical resistance measured with the current in the plane in the range of 2 ≤T≤300 K: a gradual change of behavior from continuous permalloy layers with conducting interlayer connections for t=16 Å. to isolated permalloy grains in a dielectric for the film with t= 10 Å. The percolation occurs between 12 and 10 Å, as deduced both from the magnetic and resistive properties. The discontinuous metal films were analyzed within models for thermally assisted tunneling, yielding estimates of the tunneling barrier for intralayer conduction of about 20 meV for t= 10 Å. A significant magnetic field dependence of the resistance increasing with decreasing temperature was observed in all samples.

  • 23. Calmels, Lionel
    et al.
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Atomic site sensitivity of the energy loss magnetic chiral dichroic spectra of complex oxides2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 109, no 7, p. 07D328-Article in journal (Refereed)
    Abstract [en]

    The quantitative analysis of magnetic oxide core level spectra can become complicated when the magnetic atoms are located at several nonequivalent atomic sites in the crystal. This is, for instance, the case for Fe atoms in magnetite, which are located in tetrahedral and octahedral atomic sites; in this case, the x-ray magnetic circular dichroic (XMCD) spectra recorded at the L-2,L-3 edge of Fe contain contributions from the different nonequivalent atomic sites, which unfortunately cannot be separated. Energy loss magnetic chiral dichroic (EMCD) spectra are the transmission electron microscope analogies of the XMCD spectra. One of the important differences between these two techniques of magnetic analysis is that EMCD uses a fast electron beam instead of polarized light. The fast electrons behave like Bloch states in the sample, and the fine structure of the EMCD spectra is strongly influenced by channeling and dynamical diffraction effects. These effects can be adjusted by changing the experimental configuration. We use theoretical calculations, which include dynamical diffraction effects and in which electronic transitions are treated in the atomic multiplet formalism, to show that the relative weight of the Fe atoms in different nonequivalent atomic sites can be changed by a proper choice of the position of the detector and of the magnetite sample orientation and thickness. We conclude that EMCD spectra could be used to isolate the magnetic contribution of atoms in each of the nonequivalent atomic sites, which would not be possible with XMCD techniques. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3556769]

  • 24. Chung, S.
    et al.
    Mohseni, S. M.
    Sani, S. R.
    Iacocca, E.
    Dumas, R. K.
    Nguyen, T. N. Anh
    Pogoryelov, Ye.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Muduli, P. K.
    Eklund, A.
    Hoefer, M.
    Akerman, J.
    Spin transfer torque generated magnetic droplet solitons (invited)2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, no 17Article in journal (Refereed)
    Abstract [en]

    We present recent experimental and numerical advancements in the understanding of spin transfer torque generated magnetic droplet solitons. The experimental work focuses on nano-contact spin torque oscillators (NC-STOs) based on orthogonal (pseudo) spin valves where the Co fixed layer has an easy-plane anisotropy, and the [Co/Ni] free layer has a strong perpendicular magnetic anisotropy. The NC-STO resistance and microwave signal generation are measured simultaneously as a function of drive current and applied perpendicular magnetic field. Both exhibit dramatic transitions at a certain current dependent critical field value, where the microwave frequency drops 10 GHz, modulation sidebands appear, and the resistance exhibits a jump, while the magnetoresistance changes sign. We interpret these observations as the nucleation of a magnetic droplet soliton with a large fraction of its magnetization processing with an angle greater than 90 degrees, i.e., around a direction opposite that of the applied field. This interpretation is corroborated by numerical simulations. When the field is further increased, we find that the droplet eventually collapses under the pressure from the Zeeman energy. (C) 2014 AIP Publishing LLC.

  • 25.
    Conlon, C. S.
    et al.
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA;Lawrence Berkeley Natl Lab, Mat Sci Div, Berkeley, CA 94720 USA.
    Conti, G.
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA;Lawrence Berkeley Natl Lab, Mat Sci Div, Berkeley, CA 94720 USA.
    Nemsak, S.
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA.
    Pálsson, Gunnar K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Moubah, Reda
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Kuo, C. -T
    Department of Physics, University of California, Davis, Davis, California 95616, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
    Gehlmann, M.
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA;Lawrence Berkeley Natl Lab, Mat Sci Div, Berkeley, CA 94720 USA.
    Ciston, J.
    Lawrence Berkeley Natl Lab, Mol Foundry, Natl Ctr Electron Microscopy, Berkeley, CA 94720 USA.
    Rault, J.
    SOLEIL Synchrotron, F-91190 St Aubin, France.
    Rueff, J. -P
    SOLEIL Synchrotron, 91190 Saint-Aubin, France; Sorbonne Université, CNRS, Laboratoire de Chimie Physique-Matière et Rayonnement (LCPMR), F-75005 Paris, France.
    Salmassi, F.
    Lawrence Berkeley Natl Lab, Ctr Xray Opt, Berkeley, CA 94720 USA.
    Stolte, W.
    Lawrence Berkeley Natl Lab, Adv Light Source, Berkeley, CA 94720 USA.
    Rattanachata, A.
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA;Lawrence Berkeley Natl Lab, Mat Sci Div, Berkeley, CA 94720 USA.
    Lin, S. -C
    Department of Physics, University of California, Davis, Davis, California 95616, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
    Keqi, A.
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA;Lawrence Berkeley Natl Lab, Mat Sci Div, Berkeley, CA 94720 USA.
    Saw, A.
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA;Lawrence Berkeley Natl Lab, Mat Sci Div, Berkeley, CA 94720 USA.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Fadley, C. S.
    Univ Calif Davis, Dept Phys, Davis, CA 95616 USA;Lawrence Berkeley Natl Lab, Mat Sci Div, Berkeley, CA 94720 USA.
    Hard x-ray standing-wave photoemission insights into the structure of an epitaxial Fe/MgO multilayer magnetic tunnel junction2019In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 126, no 7, article id 075305Article in journal (Refereed)
    Abstract [en]

    The Fe/MgO magnetic tunnel junction is a classic spintronic system, with current importance technologically and interest for future innovation. The key magnetic properties are linked directly to the structure of hard-to-access buried interfaces, and the Fe and MgO components near the surface are unstable when exposed to air, making a deeper probing, nondestructive, in-situ measurement ideal for this system. We have thus applied hard x-ray photoemission spectroscopy (HXPS) and standing-wave (SW) HXPS in the few kilo-electron-volt energy range to probe the structure of an epitaxially grown MgO/Fe superlattice. The superlattice consists of 9 repeats of MgO grown on Fe by magnetron sputtering on an MgO(001) substrate, with a protective Al2O3 capping layer. We determine through SW-HXPS that 8 of the 9 repeats are similar and ordered, with a period of 33 +/- 4 angstrom, with the minor presence of FeO at the interfaces and a significantly distorted top bilayer with ca. 3 times the oxidation of the lower layers at the top MgO/Fe interface. There is evidence of asymmetrical oxidation on the top and bottom of the Fe layers. We find agreement with dark-field scanning transmission electron microscope (STEM) and x-ray reflectivity measurements. Through the STEM measurements, we confirm an overall epitaxial stack with dislocations and warping at the interfaces of ca. 5 angstrom. We also note a distinct difference in the top bilayer, especially MgO, with possible Fe inclusions. We thus demonstrate that SW-HXPS can be used to probe deep buried interfaces of novel magnetic devices with few-angstrom precision.

  • 26.
    Dahbi, Mohammed
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wikberg, J. Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Saadoune, Ismael
    LCME, FST Marrakech, University Cadi Ayyad, Marocko.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrochemical behavior of LiNi1-y-zCoyMnzO2 probed through structural and magnetic properties2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 111, no 2, p. 023904-Article in journal (Refereed)
    Abstract [en]

    We have investigated LixNi1-y-zCoyMnzO2 compounds with y = 1/3, 0.25, 0.2, 0.1 and z = 1/3, 0.2, 0.1, 0.05 in order to study the influence of Ni and Mn concentration, cationic disorder, and crystallite size on the magnetic and charge/discharge behavior. The samples have been studied by means of x-ray diffraction, scanning electron microscopy, voltammetry, cycling capacity, and magnetometry. The discharge capacity increases with increasing Ni concentration as does the number of ferromagnetic interactions. With higher Mn concentration a higher capacity is observed together with formation of strong antiferromagnetic interactions driving the magnetic frustration to lower temperatures. Our results show that for sufficiently low Co concentrations a stable and magnetically more ordered structure can be obtained with excellent electrochemical properties, although a relatively large amount of Ni is present.

  • 27. d'Heurle, F
    et al.
    Petersson, CS
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Stritzker, B
    Tsai, MY
    Comparison of annealing and iion implantation effects during solid state disilicide formation1982In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 53, p. 3067-Article in journal (Refereed)
  • 28. d'Heurle, F
    et al.
    Petersson, CS
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Tsai, MY
    Observations on the hexagonal form of MoSi2 and WSi2 films produced by ion implantation and on related snow-plow effects1980In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 51Article in journal (Refereed)
  • 29.
    DJURBERG, C
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    MATTSSON, J
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    NORDBLAD, P
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    REMANENT MAGNETIZATION IN THE DILUTED ISING ANTIFERROMAGNET FE0.6ZN0.4F21994In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 75, p. 5541-5543Article in journal (Refereed)
    Abstract [en]

    The field, H less-than-or-equal-to 5 T, and temperature, T greater-than-or-equal-to 2 K, dependence of the remanent magnetization mu of the diluted Ising antiferromagnet Fe0.6Zn0.4F2 has been investigated utilizing a superconducting quantum interference device magnetometer. The results at low temperatures, where there is no growth of random field domains after the field removal, are analyzed according to mu = AH(x)(T ln t/t0)-PSI + B, where the two terms are domain wall and volume contributions to the remanent magnetization, respectively. It is found that PSI decreases continuously with decreasing temperature, and reaches a value of almost-equal-to 0.15 at 3 K. The field exponent x is found to decrease with increasing temperature, attaining values between 2 and 3. The results show a more complex behavior of the low-temperature remanent magnetization than a model proposed by Nattermann and Vilfan which predicts constant values of the exponents: PSI almost-equal-to 0.4 and x almost-equal-to 2.

  • 30.
    Donolato, M
    et al.
    Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Kongens Lyngby, Danmark, och L-NESS, Dipartimento di Fisica, Politecnico di Milano, Como, Italien.
    Dalslet, B T
    Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Kongens Lyngby, Danmark.
    Damsgaard, C D
    Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Kongens Lyngby, Danmark.
    Gunnarsson, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Jacobsen, C S
    Department of Physics, Technical University of Denmark, DTU Physics, Kongens Lyngby, Danmark.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hansen, Mikkel F
    Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Kongens Lyngby, Danmark.
    Size-dependent effects in exchange-biased planar Hall effect sensor crosses2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 109, no 6, p. 064511-Article in journal (Refereed)
    Abstract [en]

    Exchange-biased planar Hall effect magnetic field sensor crosses with arm width w have been studied as function of w. For large values of w, the magnetic behavior is hysteresis-free and follows the single domain Stoner-Wohlfarth model. When w is decreased, hysteresis is observed in the sensor response. For intermediate values of w, the magnetization reversal takes place in two steps, and for small values of w, the magnetization reversal takes place in a single step. Based on electrical measurements, magnetic force microscopy, and micromagnetic simulations, the observations are explained by an increasing magnetic shape anisotropy of the arms of the cross. We propose a simple analytical model that captures the essential physics of the observations and parameterizes the effects of the cross-shape on the central part of the cross.

  • 31. Donoval, D
    et al.
    Stolt, Lars
    Norde, Herman
    de Sousa Pires, Jorge
    Tove, PA
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Petersson, CS
    Barrier heights to silicon, of ruthenium and its silicide1982In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 53, no 7, p. 5352-Article in journal (Refereed)
  • 32. Dueñas, S.
    et al.
    Castán, H.
    Garcia, H.
    Bailón, L.
    Kukli, K.
    Ritala, M.
    Leskelä, M.
    Rooth, Mårten
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Wilhelmsson, Ola
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Hårsta, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Experimental investigation of the electrical properties of atomic layer deposited hafnium-rich silicate films on n-type silicon2006In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 100, no 9, p. 094107-Article in journal (Refereed)
    Abstract [en]

    This work examines the structural and electrical properties of HfSixOy film based metal-insulator-semiconductor capacitors by means of x-ray diffraction, x-ray photoelectron spectroscopy, capacitance-voltage (C-V), deep level transient spectroscopy, and conductance transient (G-t) techniques. Hafnium-rich silicate films were atomic layer deposited onto HF-etched or SiO2 covered silicon. Although as-deposited samples exhibit high interfacial state and disorder-induced gap state densities, a postdeposition thermal annealing in vacuum under N2 flow for 1 min at temperatures between 600 and 730 °C clearly improves the interface quality. Marked crystallization and phase separation occurred at 800 °C, increasing the structural heterogeneity and defect density in the dielectric oxide layers.

  • 33. Elihn, K
    et al.
    Landström, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Alm, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Boman, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Heszler, Peter
    Size and structure of nanoparticles formed via ultraviolet photolysis of ferrocene2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 3, p. 034311-Article in journal (Refereed)
    Abstract [en]

    Iron nanoparticles enclosed in carbon shells were formed by laser-assisted chemical vapor decomposition of ferrocene (Fe(C5H5)2) vapor in Ar gas atmosphere. The particle size dependence on the total ambient gas pressure and on laser fluence of the pulsed ArF excimer laser was examined and, e.g., an effective size decrease of the iron core was observed at elevated laser fluences. Characterizations of the iron and carbon microstructures were performed by x-ray diffraction and transmission electron microscopy, while relative iron deposition rates were measured by x-ray fluorescence spectroscopy. Both -Fe and -Fe phases were found for the single crystalline iron cores, surrounded by graphitic (inner) and amorphous (outer) carbon layers. The temperature rise of the laser-excited particles was also determined by optical spectroscopy of the emitted thermal radiation, which allowed an estimation of the iron loss of the nanoparticles due to evaporation. The estimated and measured iron losses are in good agreement.

  • 34. Emmerlich, Jens
    et al.
    Högberg, Hans
    Sasvári, Szilvia
    Persson, Per O. Å
    Hultman, Lars
    Palmquist, Jens-Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry.
    Molina-Aldareguia, Jon M
    Czigány, Zsolt
    Growth of Ti3SiC2 thin films by elemental target magnetron sputtering2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, no 9, p. 4817-4826Article in journal (Refereed)
    Abstract [en]

    Epitaxial Ti3SiC2(0001) thin films have been deposited by dc magnetron sputtering from three elemental targets of Ti, C, and Si onto MgO(111) and Al2O3(0001) substrates at temperatures of 800–900 °C. This process allows composition control to synthesize Mn + 1AXn (MAX) phases (M: early transition metal; A: A-group element; X: C and/or N; n = 1–3) including Ti4SiC3. Depositions on MgO(100) substrates yielding the Ti–Si–C MAX phases with (105), as the preferred orientation. Samples grown at different substrate temperatures, studied by means of transmission electron microscopy and x-ray diffraction investigations, revealed the constraints of Ti3SiC2 nucleation due to kinetic limitations at substrate temperatures below 700 °C. Instead, there is a competitive TiCx growth with Si segregation to form twin boundaries or Si substitutional incorporation in TiCx. Physical properties of the as-deposited single-crystal Ti3SiC2 films were determined. A low resistivity of 25 µ cm was measured. The Young's modulus, ascertained by nanoindentation, yielded a value of 343–370 GPa. For the mechanical deformation response of the material, probing with cube corner and Berkovich indenters showed an initial high hardness of almost 30 GPa. With increased maximum indentation loads, the hardness was observed to decrease toward bulk values as the characteristic kink formation sets in with dislocation ordering and delamination at basal planes.

  • 35.
    Engström, Jens
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Eriksson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Göteman, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Isberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Leijon, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Performance of large arrays of point absorbing direct-driven wave energy converters2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 114, no 20, p. 204502-Article in journal (Refereed)
    Abstract [en]

    Future commercial installation of wave energy plants using point absorber technology will require clusters of tens up to several hundred devices, in order to reach a viable electricity production. Interconnected devices also serve the purpose of power smoothing, which is especially important for devices using direct-driven power take off. The scope of this paper is to evaluate a method to optimize wave energy farms in terms of power production, economic viability and resources. In particular, the paper deals with the power variation in a large array of point-absorbing direct-driven wave energy converters, and the smoothing effect due to the number of devices and their hydrodynamic interactions. A few array geometries are compared and 34 sea states measured at the Lysekil research site at the Swedish west coast are used in the simulations. Potential linear flow theory are used with full hydrodynamic interactions between the buoys. It is shown that the variance in power production depends crucially on the geometry of the array and the number of interacting devices, but not significantly on the energy period of the waves.

  • 36.
    Engström, Jens
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Eriksson, Mikael
    Isberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Leijon, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Wave energy converter with enhanced amplitude response at frequencies coinciding with Swedish west coast sea states by use of a supplementary submerged body2009In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, no 6, article id 064512Article in journal (Refereed)
    Abstract [en]

    The full-scale direct-driven wave energy converter developed at Uppsala University has been in offshore operation at the Swedish west coast since 2006. Earlier simulations have now been validated by full-scale experiment with good agreement. Based on that, a theoretical model for a passive system having optimum amplitude response at frequencies coinciding with Swedish west coast conditions has been developed. The amplitude response is increased by adding supplementary inertia by use of the additional mass from a submerged body. A sphere with neutral buoyancy is chosen as the submerged body and modeled as being below the motion of the waves. The model is based on potential linear wave theory and the power capture ratio is studied for real ocean wave data collected at the research test site. It is found that the power capture ratio for the two body system can be increased from 30% to 60% compared to a single body system. Increased velocity in the system also decreases the value for optimal load damping from the generator, opening up the possibility to design smaller units.

  • 37.
    Engström, Jens
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Kurupath, Venugopalan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Isberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Leijon, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    A resonant Two Body System for a point absorbing Wave Energy Converter with direct-driven linear generator2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, no 12, p. 124904-Article in journal (Refereed)
    Abstract [en]

    Based on an earlier conceptual model of a two body system point absorbing wave energy converter tuned to resonance in Swedish west coast sea states, an extended coupled hydrodynamic, mechanic, and electromagnetic model has been developed. The hydrodynamic characteristics of the two body system are studied in the frequency and time domain, while its response to real Swedish west coast sea states are studied in the time domain, by using a wave energy converter model with two independently moving bodies connected to a direct driven linear generator with non-linear damping. The two body system wave energy converter gives nearly 80% power capture ratio in irregular waves. The resonant behaviour is shown to be sensitive to the shape of the spectrum, and the distance between the two bodies is shown to have a large effect on the power absorption.

  • 38.
    Eriksson, Mikael
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Waters, Rafael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Svensson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences.
    Isberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Leijon, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Wave power absorption: Experiments in open sea and simulation2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 102, no 8, p. 084910-084910-5Article in journal (Refereed)
    Abstract [en]

    A full scale prototype of a wave power plant based on a direct drive linear generator driven by a point absorber has been installed at the west coast of Sweden. In this paper, experimentally collected data of energy absorption for different electrical loads are used to verify a model of the wave power plant including the interactions of wave, buoy, generator, and external load circuit. The wave-buoy interaction is modeled with linear potential wave theory. The generator is modeled as a nonlinear mechanical damping function that is dependent on piston velocity and electric load. The results show good agreement between experiments and simulations. Potential wave theory is well suited for the modeling of a point absorber in normal operation and for the design of future converters. Moreover, the simulations are fast, which opens up for simulations of wave farms.

  • 39.
    Eriksson, Olle
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Iusan, Diana
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Theoretical Magnetism.
    Knut, Ronny
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ordering in diluted magnetic semiconductors: A magnetic percolation phenomenon (invited)2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 9, p. 09H114-Article in journal (Refereed)
    Abstract [en]

    We report on first principles calculations that describe the electronic structure, magnetic exchange interactions, and ordering temperatures of diluted magnetic semiconductors. The calculated interatomic exchange couplings are used in a Heisenberg Hamiltonian, and ordering temperatures are calculated with the use of Monte Carlo simulations. The accuracy of the method is analyzed by comparing observed and calculated ordering temperatures of several Mn and Cr doped III-V and II-VI semiconductors. The effect of magnetic percolation is discussed along with clustering phenomena and the effect of strong electron-electron interaction.

  • 40. Eyrich, C.
    et al.
    Huttema, W.
    Arora, M.
    Montoya, E.
    Rashidi, F.
    Burrowes, C.
    Kardasz, B.
    Girt, E.
    Heinrich, B.
    Mryasov, O. N.
    From, M.
    Karis, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Exchange stiffness in thin film Co alloys2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 111, no 7, p. 07C919-Article in journal (Refereed)
    Abstract [en]

    The exchange stiffness (A(ex)) is one of the key parameters controlling magnetization reversal in magnetic materials. We used a method based on the spin spiral formation in two ferromagnetic films antiferromagnetically coupled across a non-magnetic spacer layer and Brillouin scattering to measure A(ex) for a series of Co1-delta X delta (X=Cr, Ni, Ru, Pd, Pt) thin film alloys. The results show that A(ex) of Co alloys does not necessarily scale with M-s; A(ex) approximately decreases at the rate of 1.1%, 1.5%, 2.1%, 3.5%, and 5.6%, while M-s decreases at the rate of 1.1%, 0.5%, 1.1%, 3.7%, and 2.5% per addition of 1 at% of Pt, Ni, Pd, Cr, and Ru, respectively.

  • 41.
    Fang, C. M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Prediction of MAX phases, VN+1SiCN (N=1,2), from first-principles theory2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 1, p. 013511-Article in journal (Refereed)
    Abstract [en]

    We have investigated the phase stability of two MAX phases, V3SiC2 and V2SiC, by means of first-principles total-energy calculations within the generalized-gradient approximation and the projector-augmented wave method. The theoretical bulk modulus of V3SiC2 is 219 GPa, which is similar to 17% larger than that of Ti3SiC2 (187 GPa). The total-energy calculations show that V2SiC is stable with a formation energy of about 0.27 eVf.u. and that V3SiC2 is metastable (only 0.02 eVf.u. is required to stabilize this phase from its competing phases). We suggest that both these two MAX compounds should be possible to synthesize as stable (or metastable) phases using, e.g., thin-film deposition.

  • 42. Fang, Mei
    et al.
    Volotinen, Tarja T.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Kulkarni, S K
    Belova, Lyubov
    Rao, K V
    Effect of embedding Fe3O4 nanoparticles in silica spheres on the optical transmission properties of three-dimensional magnetic photonic crystals2010In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, no 10, p. 103501-Article in journal (Refereed)
    Abstract [en]

    Magnetic and optical properties of three-dimensional fcc-structured magnetic photonic crystals (MPCs), consisting of SiO2 spheres, in the size range 260-680 nm, embedded with 0-6.4 wt % Fe3O4 nanoparticles have been investigated. In the wide spatial angle transmission spectra for these crystals at normal incidence of light in the UV-visible range, five photonic band gaps (PBGs) due to Bragg diffraction from different crystal planes have been observed. The Bragg wavelengths (lambda(B)) of PBGs in both the nonmagnetic and MPCs of the same structure are found to depend linearly on the sphere size. From the slope of this linear function the calculated effective refractive index is found to increase with the concentration of the magnetite nanoparticles in the MPCs, and is consistent with the result calculated from the average dielectric constant. We also find lambda(B) of PBGs are dependent on the angle of the incidence of the light. Furthermore, for small angles this angular dependency is more strongly dependent on the polarization of incident light for MPCs than for the non-MPCs. Thus, magnetic nanocomposite PCs can be designed to incorporate additional functionality in the development of potential magneto-optical devices. c 2010 American Institute of Physics. [doi:10.1063/1.3509146]

  • 43.
    Felton, Solveig
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Fasta tillståndets fysik.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Fasta tillståndets fysik.
    Ronneteg, Sabina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. oorganisk kemi.
    Berger, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. oorganisk kemi.
    Magnetic properties of TlCu2–xFexSe2 crystals2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, no 10, p. 10B311-Article in journal (Refereed)
    Abstract [en]

    The magnetic properties of two compositions of random solutions in the TlCu2–xFexSe2 system with x=0.2 and 0.45 have been investigated by superconducting quantum interference device magnetometry. The crystal structure is of a layer type and ordering due to the iron atoms occurs at low temperatures, with Tc=85 K for x=0.2 and Tc=130 K for x=0.45. The samples were highly textured crystals and the magnetic moments of both compositions were found to align along the c axis of the structure. The saturation moments were found to be 1.5µB/Fe for x=0.2 and 0.66µB/Fe for x=0.45.

  • 44.
    Figueiredo, Nuno M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Kubart, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Sanchez-Garcia, J. A.
    Escobar Galindo, R.
    Climent-Font, A.
    Cavaleiro, A.
    Optical properties and refractive index sensitivity of reactive sputtered oxide coatings with embedded Au clusters2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, no 6, p. 063512-Article in journal (Refereed)
    Abstract [en]

    In the present study, nanocomposite coatings of Au clusters embedded in two different oxides, TiO2 and Al2O3, were synthesized using pulsed DC magnetron sputtering. The depositions were carried out in three steps, by depositing the oxide, the Au clusters, and again the oxide. The deposition time of the Au clusters was varied in order to achieve different cluster sizes, morphologies, and nanocomposite topographies. The structure, microstructure, morphology, and the optical properties of the coatings were studied. With the increase in Au content, red-shifted surface plasmon resonance (SPR) peaks with higher intensity and increased widths were observed due to changes in the metal clusters sizes and morphology and due to interparticle effects. In order to relate the peculiar SPR extinction bands with the different clusters shapes and distributions, a simulation of the optical properties of the nanocomposites was performed making use of the Renormalized Maxwell-Garnett approach. A theoretical study concerning the refractive index sensitivity was made in order to predict the optimal coatings parameters for sensing experiments. The increased surface area and the strong SPR extinction bands make these coatings suitable for gas sensing and also catalysis, albeit many other application fields can be envisaged.

  • 45. Fraerman, A. A.
    et al.
    Gribkov, B. A.
    Gusev, S. A.
    Klimov, A. Yu.
    Mironov, V. L.
    Nikitushkin, D. S.
    Rogov, V. V.
    Vdovichev, S. N.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Zabel, H.
    Magnetic force microscopy of helical states in multilayer nanomagnets2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 103, no 7, p. 073916-Article in journal (Refereed)
    Abstract [en]

    We have used magnetic force microscopy (MFM) to investigate noncollinear helical states in multilayer nanomagnets, consisting of a stack of single domain ferromagnetic disks separated by insulating nonmagnetic spacers. The nanomagnets were fabricated from a [Co/Si]x3 multilayer thin film structure by electron beam lithography and ion beam etching. The structural parameters (Co layer and spacer thicknesses) were optimized to obtain a clear spiral signature in the MFM contrast, taking into account the magnetostatic interaction between the layers. MFM contrast corresponding to the helical states with different helicities was observed for the optimized structure with Co layer thicknesses of 16, 11, and 8 nm, and with 3 nm Si spacer thickness.

  • 46.
    Frenning, Göran
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
    Jonsson, AnnaKarin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Larsson, A.-L.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Materials Science.
    Theoretical investigation of ion conduction in three-layered ion-conductor systems: Derivation of the isothermal transient ionic current and frequency-dependent impedance2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 94, p. 1629-Article in journal (Refereed)
    Abstract [en]

    Ion conduction in three-layered ion-conductor systems is considered. Explicit analytic expressions for the isothermal transient ionic current and frequency-dependent impedance are derived. The analysis includes migration, diffusion and space-charge effects as contributors to the ionic motion. The resulting model allows conduction parameters such as diffusion coefficients and ion concentrations in three different layers to be obtained from one single measurement, either in the time or in the frequency domain. The implications of one or more of the layers being mixed ionic/electronic conductors are discussed, and it is argued that the proposed model provides a useful description of the coupled ionic/electronic motion occurring in such a mixed-conductor system.

  • 47.
    Frenning, Göran
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science.
    Theoretical derivation of the isothermal transient ionic current in an ion conductor: Migration, diffusion, and space-charge effects2001In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 90, no 11, p. 5570-5575Article in journal (Refereed)
    Abstract [en]

    The Green’s function technique was used to determine the isothermal transient ionic current (ITIC) caused by the application of a constant potential across an ion conductor which initially contained the ions under consideration. The analysis included migration, diffusion, and space-charge effects as contributions to the ionic motion. Furthermore, the relative importance of diffusion and space-charge effects as currentlimiters was investigated. It was found that ion concentrations as low as ∼1016–1017 cm−3 are sufficient to make space-charge effects the dominant contribution to the decay of the ITIC at low applied electric fields(∼104 V/cm). Hence such effects should be taken into consideration when the ITIC method is used to determine conduction parameters.

  • 48. Fu, Yu
    et al.
    Barsukov, I.
    Meckenstock, R.
    Lindner, J.
    Zhai, Y.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Farle, M.
    Uniaxial anisotropy and its manipulation in amorphous Co68Fe24Zr8 thin films (invited)2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 115, no 17, p. 172605-Article in journal (Refereed)
    Abstract [en]

    We have proven that the growth of Co68Fe24Zr8 layers under external field yields a uniaxial anisotropy, defined by the direction of the field. No magnetic coupling is present between Co68Fe24Zr8 layers when separated by a 3 nm of Al70Zr30. The anisotropy axis can therefore be manipulated at will and the direction can be tailored, layer by layer in multilayers, by the choice of the direction of the applied field during growth. The g-factor (2.13) and the anisotropy constant, obtained from ferromagnetic resonance, support the existence of short-range order. The relation between the temperature dependences of magnetic anisotropy and magnetization are partially captured by Callen-Callen power law. (C) 2014 AIP Publishing LLC.

  • 49. Fu, Yu
    et al.
    Barsukov, I.
    Raanaei, Hossein
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Spasova, M.
    Lindner, J.
    Meckenstock, R.
    Farle, M.
    Hjörvarsson, Björgvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Tailored magnetic anisotropy in an amorphous trilayer2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 109, no 11, p. 113908-Article in journal (Refereed)
    Abstract [en]

    An amorphous Co68Fe24Zr8(3 nm)/Al70Zr30(3 nm)/Co68Fe24Zr8(3 nm) trilayer system has been investigated using in-plane and out-of-plane angular dependent ferromagnetic resonance at different frequencies. The in-plane magnetic anisotropy is uniaxial, retaining its value of (2.9 +/- 0.1) x 10(3) J/m(3) for each magnetic layer, whereas its direction was tailored independently in an arbitrary manner by applying an external magnetic field during the film deposition. The perpendicular anisotropy constant, supposed to reflect the interface quality, is nearly identical for both layers. Furthermore, the magnetic layers act independently upon each other due to the absence of interlayer coupling.

  • 50.
    Gabrysch, Markus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Majdi, Saman
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Twitchen, Daniel
    Element Six Ltd, Ascot Berkshire, UK.
    Isberg, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Electricity.
    Electron and hole drift velocity in chemical vapor deposition diamond2011In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 109, no 6, p. 063719-Article in journal (Refereed)
    Abstract [en]

    The time-of-flight technique has been used to measure the drift velocities for electrons and holes in high-purity single-crystalline CVD diamond. Measurements were made in the temperature interval 83 ≤ T ≤ 460 K and for electric fields between 90 and 4 × 103 V/cm, applied in the <100> crystallographic direction. The study includes low-field drift mobilities and is performed in the low-injection regime to perturb the applied electric field only minimally.

1234 1 - 50 of 198
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