@article{4153, abstract = {{Nanosphere lithography (NSL) masks consisting of mono- or double-layers of polystyrene (PS) nano-beads are fabricated on silicon exploiting the self-organization of PS particles during the controlled drying of a colloidal suspension on a surface. The shape changes and shrinkage of PS sphere masks upon treatment in an air plasma are studied as a function of initial sphere size, plasma power and treatment time. The influence of several experimental parameters, including the plasma induced temperature rise, are analysed using scanning and transmission electron microscopy. It is demonstrated that a variety of new intriguing nanopatterns can be generated on silicon surfaces by the combination of NSL and plasma techniques, largely broadening the variety of patterns available so far by NSL.}}, author = {{Gogel, D. and Weinl, M. and Lindner, Jörg and Stritzker, B.}}, journal = {{JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS}}, number = {{3}}, pages = {{740--744}}, title = {{{Plasma modification of nanosphere lithography masks made of polystyrene beads}}}, volume = {{12}}, year = {{2010}}, } @article{4194, abstract = {{A heterojunction field-effect transistor (HFET) was fabricated of nonpolar cubic AlGaN/GaN grown on Ar+ implanted 3C–SiC (001) by molecular beam epitaxy. The device shows a clear field effect at positive bias voltages with V_th=0.6 V. The HFET output characteristics were calculated using ATLAS simulation program. The electron channel at the cubic AlGaN/GaN interface was detected by room temperature capacitance-voltage measurements.}}, author = {{Tschumak, E. and Granzner, R. and Lindner, Jörg and Schwierz, F. and Lischka, K. and Nagasawa, H. and Abe, M. and As, Donald}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{25}}, publisher = {{AIP Publishing}}, title = {{{Nonpolar cubic AlGaN/GaN heterojunction field-effect transistor on Ar+ implanted 3C–SiC (001)}}}, doi = {{10.1063/1.3455066}}, volume = {{96}}, year = {{2010}}, } @article{4200, abstract = {{We studied the Fulde-Ferrell-Larkin-Ovchinnikov-type state established due to the proximity effect in superconducting Nb/Cu_41Ni_59 bilayers. Using a special wedge-type deposition technique, series of 20–35 samples could be fabricated by magnetron sputtering during one run. The layer thickness of only a few nanometers, the composition of the alloy, and the quality of interfaces were controlled by Rutherford backscattering spectrometry, high-resolution transmission electron microscopy, and Auger spectroscopy. The magnetic properties of the ferromagnetic alloy layer were characterized with superconducting quantum interference device magnetometry. These studies yield precise information about the thickness and demonstrate the homogeneity of the alloy composition and magnetic properties along the sample series. The dependencies of the critical temperature on the Nb and Cu41Ni59 layer thickness, T_c(d_S) and T_c(d_F), were investigated for constant thickness d_F of the magnetic alloy layer and d_S of the superconducting layer, respectively. All types of nonmonotonic behaviors of T_c versus d_F predicted by the theory could be realized experimentally, from reentrant superconducting behavior with a broad extinction region to a slight suppression of superconductivity with a shallow minimum. Even a double extinction of superconductivity was observed, giving evidence for the multiple reentrant behavior predicted by theory. All critical temperature curves were fitted with suitable sets of parameters. Then, T_c(d_F) diagrams of a hypothetical ferromagnet/superconductor/ferromagnet spin-switch core structure were calculated using these parameters. Finally, superconducting spin-switch fabrication issues are discussed in detail in view of the achieved results.}}, author = {{Zdravkov, V. I. and Kehrle, J. and Obermeier, G. and Gsell, S. and Schreck, M. and Müller, C. and Krug von Nidda, H.-A. and Lindner, Jörg and Moosburger-Will, J. and Nold, E. and Morari, R. and Ryazanov, V. V. and Sidorenko, A. S. and Horn, S. and Tidecks, R. and Tagirov, L. R.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{5}}, publisher = {{American Physical Society (APS)}}, title = {{{Reentrant superconductivity in superconductor/ferromagnetic-alloy bilayers}}}, doi = {{10.1103/physrevb.82.054517}}, volume = {{82}}, year = {{2010}}, } @article{4204, abstract = {{A comparative theoretical investigation of carbon interstitials in silicon is presented. Calculations using classical potentials are compared to first-principles density-functional theory calculations of the geometries, formation, and activation energies of the carbon dumbbell interstitial, showing the importance of a quantummechanical description of this system. In contrast to previous studies, the present first-principles calculations of the interstitial carbon migration path yield an activation energy that excellently matches the experiment. The bond-centered interstitial configuration shows a net magnetization of two electrons, illustrating the need for spin-polarized calculations.}}, author = {{Zirkelbach, F. and Stritzker, B. and Nordlund, K. and Lindner, Jörg and Schmidt, W. G. and Rauls, E.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{9}}, publisher = {{American Physical Society (APS)}}, title = {{{Defects in carbon implanted silicon calculated by classical potentials and first-principles methods}}}, doi = {{10.1103/physrevb.82.094110}}, volume = {{82}}, year = {{2010}}, } @inproceedings{4206, author = {{Lindner, Jörg}}, location = {{Universidad Autónoma de Madrid (Spain)}}, title = {{{Advanced topics and applications of Transmission Electron Microscopy, Part I-II}}}, year = {{2010}}, } @book{4207, editor = {{Ila, D. and Kishimoto, N. and Lindner, Jörg and Baglin, J.}}, isbn = {{978-1-60511-154-4}}, location = {{San Francisco (USA)}}, publisher = {{MRS Symposium Proceedings }}, title = {{{Ion Beams and Nano-Engineering}}}, volume = {{1181}}, year = {{2010}}, } @article{4152, abstract = {{A novel technique to form periodically nanostructured Si surface morphologies based on nanosphere lithography (NSL) and He ion implantation induced swelling is studied in detail. It is shown that by implantation of keV He ions through the nanometric openings of NSL masks regular arrays of hillocks and rings can be created on silicon surfaces. The shape and size of these surface features can be easily controlled by adjusting the ion dose and energy as well as the mask size. Feature heights of more than 100 nm can be obtained, while feature distances are typically 1.15 or 2 (hillock or ring) nanosphere radii, which are chosen to be between 100 and 500 nm in this study. Atomic force and scanning electron microscopy measurements of the surface morphology are supplemented by cross-sectional transmission electron microscopy, revealing the inner structure of hillocks to consist of a central cavity surrounded by a hierarchical arrangement of smaller voids. The surface morphologies developed here have the potential to be useful for fixing and separating nano-objects on a silicon surface.}}, author = {{Fischer, Frederic J.C. and Weinl, Michael and Lindner, Jörg and Stritzker, Bernd}}, issn = {{1946-4274}}, journal = {{MRS Proceedings}}, location = {{San Franicsco (USA)}}, publisher = {{Cambridge University Press (CUP)}}, title = {{{Nanoscale Surface Patterning of Silicon Using Local Swelling Induced by He Implantation through NSL-Masks}}}, doi = {{10.1557/proc-1181-dd10-02}}, volume = {{1181}}, year = {{2009}}, } @article{4192, abstract = {{Buried ion beam synthesized 3C-SiC layers were revealed to the surface of silicon wafers to provide lattice matched substrates for GaN thin film epitaxy. Both epitaxial SiC/Si(1 1 1) and SiC/Si(0 0 1) growth surfaces with either six- or four-fold crystal symmetry, respectively, were formed. GaN thin film growth was achieved by ion beam assisted molecular beam epitaxy (IBA–MBE) which – owing to the energy and momentum transfer of the ions – allows to deposit epitaxial thin films at particularly low growth temperatures where both the stable hexagonal and the metastable cubic polytype of GaN can be formed. It is shown by X-ray diffraction (XRD) and cross-sectional transmission electron microscopy (XTEM) that using appropriate fluxes of Ga atoms both purely hexagonal and purely cubic GaN films can be grown epitaxially on SiC/Si(1 1 1) and SiC/Si(0 0 1), respectively. Thereby Ga rich growth conditions seem to stabilize the formation of the cubic polytype. It is obvious from XTEM studies that the high density of crystal defects in the SiC layer is not transferred onto the growing GaN films and that the crystalline quality of GaN films improves with increasing film thickness. The influence of surface roughness and wettability, interfacial cavities and the nucleation of twin-type defects at the GaN/SiC interface on the crystalline quality of the GaN thin films is discussed.}}, author = {{Häberlen, M. and Gerlach, J.W. and Murphy, B. and Lindner, Jörg and Stritzker, B.}}, issn = {{0022-0248}}, journal = {{Journal of Crystal Growth}}, number = {{6}}, pages = {{762--769}}, publisher = {{Elsevier BV}}, title = {{{Structural characterization of cubic and hexagonal GaN thin films grown by IBA–MBE on SiC/Si}}}, doi = {{10.1016/j.jcrysgro.2009.12.048}}, volume = {{312}}, year = {{2009}}, } @article{4196, abstract = {{The growth of cubic group III-nitrides is a direct way to eliminate polarization effects, which inherently limit the fabrication of normally-off heterojunction field-effect transistors (HFETs) in GaN technology. HFET structures were fabricated of non-polar cubic AlGaN/GaN hetero layers grown by plasma assisted molecular beam epitaxy (MBE) on free standing 3C-SiC (001). The electrical insulation of 3C-SiC was realised by Ar+ implantation before c-AlGaN/GaN MBE. The structural properties of the epilayers were studied by highresolution x-ray diffraction (HRXRD). HFETs with normally off and normally-on characteristics were fabricated of cubic AlGaN/GaN. Capacitance-voltage (CV) characteristics of thegate contact were performed to detect the electron channel at the c-AlGaN/GaN hetero interface.}}, author = {{Tschumak, Elena and Lindner, Jörg and Bürger, M. and Lischka, K. and Nagasawa, H. and Abe, M. and As, Donald}}, issn = {{1862-6351}}, journal = {{physica status solidi (c)}}, number = {{1}}, pages = {{104--107}}, publisher = {{Wiley}}, title = {{{Non-polar cubic AlGaN/GaN HFETs grown by MBE on Ar+implanted 3C-SiC (001)}}}, doi = {{10.1002/pssc.200982615}}, volume = {{7}}, year = {{2009}}, } @article{4221, abstract = {{Nanopatterning of silicon surfaces by means of He+ ion implantation through self-organized colloidal masks is reported for the first time. Nanosphere lithography (NSL) masks with mask openings of 46– 230 nm width were deposited on Si(100) wafers. He+ ions were implanted through these masks in order to induce a local cavity formation and Si surface swelling. The surface morphology and the subsurface structure were studied using atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (XTEM), respectively, as a function of mask and implantation parameters. It is demonstrated that regular arrays of both individual hillocks and trough-like circular rings can be generated.}}, author = {{Lindner, Jörg and Seider, C. and Fischer, F. and Weinl, M. and Stritzker, B.}}, issn = {{0168-583X}}, journal = {{Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms}}, number = {{8-9}}, pages = {{1394--1397}}, publisher = {{Elsevier BV}}, title = {{{Regular surface patterns by local swelling induced by He implantation into silicon through nanosphere lithography masks}}}, doi = {{10.1016/j.nimb.2009.01.052}}, volume = {{267}}, year = {{2009}}, } @article{4223, abstract = {{The formation of a thick protective oxide layer on NiTi by plasma immersion ion implantation (PIII) for medical devices is an established technology on the laboratory scale. It is shown here that by pre-implantation with either 180 keV Ni or low fluence of 190 MeV Au ions, a radiation suppressed growth of the oxide layer of up to 40% is observed. At higher Au fluence and higher PIII temperatures, this changes into an enhancement of 25–40%. Different amorphisation mechanisms or disorder formation is proposed as the underlying effect.}}, author = {{Lutz, J. and Gerlach, J.W. and Lindner, Jörg and Assmann, W. and Mändl, S.}}, issn = {{0168-583X}}, journal = {{Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms}}, number = {{8-9}}, pages = {{1634--1637}}, publisher = {{Elsevier BV}}, title = {{{Radiation suppressed oxide growth in the system Ni–Ti–O}}}, doi = {{10.1016/j.nimb.2009.01.068}}, volume = {{267}}, year = {{2009}}, } @inproceedings{4231, author = {{Lindner, Jörg}}, location = {{ Universidad Autónoma de Madrid (Spain)}}, title = {{{Characterisation of nanostructured materials for electronic and photonic information processing}}}, year = {{2009}}, } @inproceedings{4232, author = {{Lindner, Jörg}}, location = {{Bad Karlshafen (Germany)}}, title = {{{Ion Implantation: Fundamental Aspects and Recent Applications}}}, year = {{2009}}, } @inproceedings{4233, author = {{Lindner, Jörg}}, location = {{Bochum (Germany)}}, title = {{{Ionenstrahlmodifikation kleiner Oberflächenbereiche mittels selbstorganisierter Nanomasken}}}, year = {{2009}}, } @inproceedings{4234, author = {{Reichardt, F. and Weinl, M. and Gogel, D. and Wätje, K. and Wixforth, A. and Stritzker, B. and Lindner, Jörg}}, location = {{Straßburg (France)}}, title = {{{Synthesis of 2D-Nanostructured ZnO Thin Films using Nanosphere Lithography and Sputter Deposition}}}, year = {{2009}}, } @article{4229, abstract = {{The precipitation process of silicon carbide in heavily carbon doped silicon is not yet fully understood. High resolution transmission electron microscopy observations suggest that in a first step carbon atoms form C Si dumbbells on regular Si lattice sites which agglomerate into large clusters. In a second step, when the cluster size reaches a radius of a fewnm, the high interfacial energy due to the SiC/Si lattice misfit of almost 20% is overcome and the precipitation occurs. By simulation, details of the precipitation process can be obtained on the atomic level. A recently proposed parametrization of a Tersoff-like bond order potential is used to model the system appropriately. Preliminary results gained by molecular dynamics simulations using this potential are presented.}}, author = {{Zirkelbach, F. and Lindner, Jörg and Nordlund, K. and Stritzker, B.}}, issn = {{0921-5107}}, journal = {{Materials Science and Engineering: B}}, pages = {{149--152}}, publisher = {{Elsevier BV}}, title = {{{Molecular dynamics simulation of defect formation and precipitation in heavily carbon doped silicon}}}, doi = {{10.1016/j.mseb.2008.10.010}}, volume = {{159-160}}, year = {{2008}}, }