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  • 151.
    Seppänen, Timo
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Radnoczi, G.Z.
    Radnóczi, G.Z., Research Institute for Technical Physics and Materials Science (MFA), Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary.
    Magnetron sputter epitaxy of wurtzite Al1-x Inx N (0.12005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 97, no 8, p. 083503-Article in journal (Refereed)
    Abstract [en]

    Ternary wurtzite Al1-x Inx N thin films with compositions throughout the miscibility gap have been grown onto seed layers of TiN and ZrN by magnetron sputter epitaxy (MSE) using dual reactive direct current magnetron sputter deposition under ultra high vacuum conditions. The film compositions were calculated using Vegard's law from lattice parameters determined by x-ray diffraction (XRD). XRD showed that single-phase Al1-x Inx N alloy films in the wurtzite structure with [0.10 TiN,ZrN <110>. At higher substrate temperatures almost pure AlN was formed. The microstructure of the films was also investigated by high-resolution electron microscopy. A columnar growth mode with epitaxial column widths from 10 to 200 nm was observed. Rocking curve full-width-at-half-maximum measurements revealed highly stressed lattices for growth onto TiN at 600°C. Pseudobinary MSE growth phase field diagrams for Al1-x Inx N onto ZrN and TiN were established for substrate temperatures up to 1000°C. Large regimes for single-phase solid solutions were thus identified with In being the diffusing species. © 2005 American Institute of Physics.

  • 152.
    Serban, Alexandra
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Junaid, Muhammad
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tengdelius, Lina
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per Ola Åke
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnetron Sputter Epitaxy of High-Quality GaN Nanorods on Functional and Cost-Effective Templates/Substrates2017In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 9, article id 1322Article in journal (Refereed)
    Abstract [en]

    We demonstrate the versatility of magnetron sputter epitaxy by achieving high-quality GaN nanorods on different substrate/template combinations, specifically Si, SiC, TiN/Si, ZrB2/Si, ZrB2/SiC, Mo, and Ti. Growth temperature was optimized on Si, TiN/Si, and ZrB2/Si, resulting in increased nanorod aspect ratio with temperature. All nanorods exhibit high purity and quality, proved by the strong bandedge emission recorded with cathodoluminescence spectroscopy at room temperature as well as transmission electron microscopy. These substrates/templates are affordable compared to many conventional substrates, and the direct deposition onto them eliminates cumbersome post-processing steps in device fabrication. Thus, magnetron sputter epitaxy offers an attractive alternative for simple and affordable fabrication in optoelectronic device technology.

  • 153.
    Serban, Alexandra
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Yeh, Chia-Cheng
    National Cheng Kung University, Taiwan.
    Hsu, Hsu-Cheng
    National Cheng Kung University, Taiwan.
    Tsai, Yu-Lin
    National Chiao Tung University, Taiwan.
    Kuo, Hao-Chung
    National Chiao Tung University, Taiwan.
    Junaid, Muhammad
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Selective-area growth of single-crystal wurtzite GaN nanorods on SiOx/Si(001) substrates by reactive magnetron sputter epitaxy exhibiting single-mode lasing2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 12701Article in journal (Refereed)
    Abstract [en]

    Selective-area growth (SAG) of single-crystal wurtzite GaN nanorods (NRs) directly onto Si(001) substrates with un-etched native SiOx amorphous layer, assisted by a patterning TiNx mask fabricated by nanosphere lithography (NSL), has been realized by reactive magnetron sputter epitaxy (MSE). The GaN NRs were grown vertically to the substrate surface with the growth direction along c-axis in the well-defined nano-opening areas. A 5-step structural and morphological evolution of the SAG NRs observed at different sputtering times depicts a comprehensive growth model, listed in sequence as: formation of a polycrystalline wetting layer, predominating c-axis oriented nucleation, coarsening and coalescence of multi-islands, single NR evolution, and finally quasi-equilibrium crystal shape formation. Room-temperature cathodoluminescence spectroscopy shows a strong GaN bandedge emission with a uniform luminescence across the NRs, indicating that the SAG NRs are grown with high quality and purity. In addition, single-longitudinal-mode lasing, attributed to well-faceted NR geometry forming a Fabry-Perot cavity, was achieved by optical pumping, paving a way for fabricating high-performance laser optoelectronics using MSE.

  • 154.
    Serban, Alexandra
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Poenaru, Iuliana
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Junaid, Junaid
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Structural and compositional evolutions of InxAl1-xN core-shell nanorods grown on Si(111) substrates by reactive magnetron sputter epitaxy2015In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 26, no 21, p. 215602-Article in journal (Refereed)
    Abstract [en]

    Catalystless growth of InxAl1-xN core-shell nanorods have been realized by reactive magnetron sputter epitaxy onto Si(111) substrates. The samples were characterized by scanning electron microscopy, x-ray diffraction, scanning transmission electron microscopy, and energy dispersive x-ray spectroscopy. The composition and morphology of InxAl1-xN nanorods are found to be strongly influenced by the growth temperature. At lower temperatures, the grown materials form well-separated and uniform core-shell nanorods with high In-content cores, while a deposition at higher temperature leads to the formation of an Al-rich InxAl1-xN film with vertical domains of low In-content as a result of merging Al-rich shells. The thickness and In content of the cores (domains) increase with decreasing growth temperature. The growth of the InxAl1-xN is traced to the initial stage, showing that the formation of the core-shell nanostructures starts very close to the interface. Phase separation due to spinodal decomposition is suggested as the origin of the resultant structures. Moreover, the in-plane crystallographic relationship of the nanorods and substrate was modified from a fiber textured to an epitaxial growth with an epitaxial relationship of InxAl1-xN[0001]//Si[111] and InxAl1-xN[11 (2) over bar0]//Si[1 (1) over bar0] by removing the native SiOx layer from the substrate.

  • 155.
    Serban, Elena Alexandra
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per Ola Åke
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Site-controlled growth of GaN nanorod arrays by magnetron sputter epitaxy2018In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 660, p. 950-955Article in journal (Refereed)
    Abstract [en]

    Catalyst-free GaN nanorod regular arrays have been realized by reactive magnetron sputter epitaxy. Two nanolithographic methods, nanosphere lithography (NSL) and focused ion beam lithography (FIBL), were applied to pattern Si substrates with TiNx masks. The growth temperature was optimized for achieving selectivity and well-faceted nanorods grown onto the NSL-patterned substrates. With increasing temperature from 875 to 985 °C, we observe different growth behaviors and associate them with selective insensitive, diffusion-dominated, and desorption-dominated zones. To further achieve site-specific and diameter control, these growth parameters were transferred onto FIBL-patterned substrates. Further investigation into the FIBL process through tailoring of milling current and time in combination with varying nanorod growth temperature, suggests that minimization of mask and substrate damage is the key to attain uniform, well-defined, single, and straight nanorods. Destruction of the mask results in selective area growth failure, while damage of the substrate surface promotes inclined nanorods grown into the openings, owning to random oriented nucleation.

  • 156.
    Sundqvist, B
    et al.
    Umea Univ, Dept Expt Phys, S-90187 Umea, Sweden Chalmers Univ Technol, Dept Expt Phys, S-41296 Gothenburg, Sweden Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Univ Paris Sud, Phys Solides Lab, F-91405 Orsay, France.
    Wagberg, T
    Umea Univ, Dept Expt Phys, S-90187 Umea, Sweden Chalmers Univ Technol, Dept Expt Phys, S-41296 Gothenburg, Sweden Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Univ Paris Sud, Phys Solides Lab, F-91405 Orsay, France.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Jacobsson, P
    Umea Univ, Dept Expt Phys, S-90187 Umea, Sweden Chalmers Univ Technol, Dept Expt Phys, S-41296 Gothenburg, Sweden Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Univ Paris Sud, Phys Solides Lab, F-91405 Orsay, France.
    Stafström, Sven
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Moret, R
    Umea Univ, Dept Expt Phys, S-90187 Umea, Sweden Chalmers Univ Technol, Dept Expt Phys, S-41296 Gothenburg, Sweden Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Univ Paris Sud, Phys Solides Lab, F-91405 Orsay, France.
    Launois, P
    Umea Univ, Dept Expt Phys, S-90187 Umea, Sweden Chalmers Univ Technol, Dept Expt Phys, S-41296 Gothenburg, Sweden Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Univ Paris Sud, Phys Solides Lab, F-91405 Orsay, France.
    Structure and stability of pressure polymerized C-602000In: Molecular crystals and liquid crystals science and technology, ISSN 1058-7276, E-ISSN 1563-5295, Vol. 13, no 1-4, p. 117-122Article in journal (Refereed)
    Abstract [en]

    We discuss the bond energy of the orthorhombic C-60 polymer and the structure of the two-dimensional C-60 polymers. For the orthorhombic polymer, measurements of the dissociation energy by different methods give results that differ by a factor of two. We show that optical excitations lead to a temporary weakening of the intermolecular bonds and optical measurements thus show a low apparent bond energy. We have also polymerized a single crystal of C-60 into two-dimensional phases. X-ray diffraction studies of this crystal has enabled us to determine the stacking sequences of both the tetragonal and rhombohedral structures.

  • 157. Svensson, BG
    et al.
    Hallen, A
    Royal Inst Technol, SE-16440 Kista, Sweden Univ Oslo, Dept Phys, NO-0316 Oslo, Norway Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Australian Natl Univ, Canberra, ACT 0200, Australia CSIC, CNM, ES-08193 Bellaterra, Spain.
    Linnarsson, MK
    Royal Inst Technol, SE-16440 Kista, Sweden Univ Oslo, Dept Phys, NO-0316 Oslo, Norway Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Australian Natl Univ, Canberra, ACT 0200, Australia CSIC, CNM, ES-08193 Bellaterra, Spain.
    Kuznetsov, AY
    Royal Inst Technol, SE-16440 Kista, Sweden Univ Oslo, Dept Phys, NO-0316 Oslo, Norway Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Australian Natl Univ, Canberra, ACT 0200, Australia CSIC, CNM, ES-08193 Bellaterra, Spain.
    Janson, MS
    Aberg, D
    Royal Inst Technol, SE-16440 Kista, Sweden Univ Oslo, Dept Phys, NO-0316 Oslo, Norway Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Australian Natl Univ, Canberra, ACT 0200, Australia CSIC, CNM, ES-08193 Bellaterra, Spain.
    Osterman, J
    Royal Inst Technol, SE-16440 Kista, Sweden Univ Oslo, Dept Phys, NO-0316 Oslo, Norway Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Australian Natl Univ, Canberra, ACT 0200, Australia CSIC, CNM, ES-08193 Bellaterra, Spain.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Storasta, Liutauras
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Carlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Bergman, JP
    Royal Inst Technol, SE-16440 Kista, Sweden Univ Oslo, Dept Phys, NO-0316 Oslo, Norway Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Australian Natl Univ, Canberra, ACT 0200, Australia CSIC, CNM, ES-08193 Bellaterra, Spain.
    Jagadish, C
    Royal Inst Technol, SE-16440 Kista, Sweden Univ Oslo, Dept Phys, NO-0316 Oslo, Norway Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Australian Natl Univ, Canberra, ACT 0200, Australia CSIC, CNM, ES-08193 Bellaterra, Spain.
    Morvan, E
    Royal Inst Technol, SE-16440 Kista, Sweden Univ Oslo, Dept Phys, NO-0316 Oslo, Norway Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Australian Natl Univ, Canberra, ACT 0200, Australia CSIC, CNM, ES-08193 Bellaterra, Spain.
    Doping of silicon carbide by ion implantation2001In: Materials Science Forum, Vols. 353-356, Trans Tech Publications Inc., 2001, Vol. 353-356, p. 549-554Conference paper (Refereed)
    Abstract [en]

    A brief survey is given of some recent results on doping of 4H- and 6H-SiC by ion implantation. The doses and energies used are between 10(9) and 10(15) cm(-2) and 100 keV and 5 MeV, respectively, and B and Al ions (p-type dopants) are predominantly studied. After low dose implantation (less than or equal to 10(10) cm(-2)) a strong compensation is observed in n-type samples and this holds irrespective of implantation temperature up to 600 degreesC. However, at higher doses (10(14)-10(15) Al/cm(2)) the rate of defect recombination (annihilation) increases substantially during hot implants (greater than or equal to 200 degreesC) and in these samples one type of structural defect dominates after past-implant annealing at 1700-2000 degreesC. The defect is identified as a dislocation loop composed of clustered interstitial atoms inserted on the basal plane in the hexagonal crystal structure. Finally, transient enhanced diffusion (TED) of ion-implanted boron in 4H-samples is discussed.

  • 158. Söderberg, Hans
    et al.
    Flink, Axel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Beckers, Manfred
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Growth and characterization of TiN/SiN(001) superlattice films2007In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 22, no 11, p. 3255-3264Article in journal (Refereed)
    Abstract [en]

    We report the layer structure and composition in recently discovered TiN/SiN(001) superlattices deposited by dual-reactive magnetron sputtering on MgO(001) substrates. High-resolution transmission electron microscopy combined with Z-contrast scanning transmission electron microscopy, x-ray reflection, diffraction, and reciprocal-space mapping shows the formation of high-quality superlattices with coherently strained cubic TiN and SiN layers for SiN thickness below 7–10 Å. For increasing SiN layer thicknesses, a transformation from epitaxial to amorphous SiNx (x ? 1) occurs during growth. Elastic recoil detection analysis revealed an increase in nitrogen and argon content in SiNx layers during the phase transformation. The oxygen, carbon, and hydrogen contents in the multilayers were around the detection limit (~0.1 at.%) with no indication of segregation to the layer interfaces. Nanoindentation experiments confirmed superlattice hardening in the films. The highest hardness of 40.4 ± 0.8 GPa was obtained for 20-Å TiN with 5-Å-thick SiN(001) interlayers, compared to monolithic TiN at 20.2 ± 0.9 GPa.

  • 159.
    Ta, Huy Q.
    et al.
    Soochow Univ, Peoples R China; Polish Acad Sci, Poland.
    Zhao, Liang
    Soochow Univ, Peoples R China.
    Yin, Wanjian
    Soochow Univ, Peoples R China.
    Pohl, Darius
    IFW Dresden, Germany.
    Rellinghaus, Bernd
    IFW Dresden, Germany.
    Gemming, Thomas
    IFW Dresden, Germany.
    Trzebicka, Barbara
    Polish Acad Sci, Poland.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jing, Gao
    Soochow Univ, Peoples R China.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Liu, Zhongfan
    Soochow Univ, Peoples R China; Peking Univ, Peoples R China.
    Bachmatiuk, Alicja
    Soochow Univ, Peoples R China; Polish Acad Sci, Poland; IFW Dresden, Germany.
    Rummeli, Mark H.
    Soochow Univ, Peoples R China; Polish Acad Sci, Poland; IFW Dresden, Germany.
    Single Cr atom catalytic growth of graphene2018In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 11, no 5, p. 2405-2411Article in journal (Refereed)
    Abstract [en]

    Single atoms are the ultimate minimum size limit for catalysts. Graphene, as an exciting, ultimately thin (one atom thick) material can be imaged in a transmission electron microscope with relatively few imaging artefacts. Here, we directly observe the behavior of single Cr atoms in graphene mono- and di-vacancies and, more importantly, at graphene edges. Similar studies at graphene edges with other elemental atoms, with the exception of Fe, show catalytic etching of graphene. Fe atoms have been shown to both etch and grow graphene. In contrast, Cr atoms are only observed to induce graphene growth. Complementary theoretical calculations illuminate the differences between Fe and Cr, and confirm single Cr atoms as superior catalysts for sp(2) carbon growth.

  • 160.
    Tao, Quanzheng
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kota, Sankalp
    Drexel University, PA 19104 USA.
    Meshkian, Rahele
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Halim, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Barsoum, Michel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Drexel University, PA 19104 USA.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Two-dimensional Mo1.33C MXene with divacancy ordering prepared from parent 3D laminate with in-plane chemical ordering2017In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, article id 14949Article in journal (Refereed)
    Abstract [en]

    The exploration of two-dimensional solids is an active area of materials discovery. Research in this area has given us structures spanning graphene to dichalcogenides, and more recently 2D transition metal carbides (MXenes). One of the challenges now is to master ordering within the atomic sheets. Herein, we present a top-down, high-yield, facile route for the controlled introduction of ordered divacancies in MXenes. By designing a parent 3D atomic laminate, (Mo2/3Sc1/3)(2)AlC, with in-plane chemical ordering, and by selectively etching the Al and Sc atoms, we show evidence for 2D Mo1.33C sheets with ordered metal divacancies and high electrical conductivities. At similar to 1,100 F cm(-3), this 2D material exhibits a 65% higher volumetric capacitance than its counterpart, Mo2C, with no vacancies, and one of the highest volumetric capacitance values ever reported, to the best of our knowledge. This structural design on the atomic scale may alter and expand the concept of property-tailoring of 2D materials.

  • 161.
    Tholander, Christopher
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tasnádi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Sandström, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany.
    Zukauskaitè, Agne
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Fraunhofer Institute for Applied Solid State Physics IAF, Freiburg, Germany.
    Ab initio calculations and experimental study of piezoelectric YxIn1-xN thin films deposited using reactive magnetron sputter epitaxy2016In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 105, p. 199-206Article in journal (Refereed)
    Abstract [en]

    By combining theoretical prediction and experimental verification we investigate the piezoelectric properties of yttrium indium nitride (YxIn1-xN). Ab initio calculations show that the YxIn1-xN wurtzite phase is lowest in energy among relevant alloy structures for 0≤x≤0.5. Reactive magnetron sputter epitaxy was used to prepare thin films with Y content up to x=0.51. The composition dependence of the lattice parameters observed in the grown films is in agreement with that predicted by the theoretical calculations confirming the possibility to synthesize a wurtzite solid solution. An AlN buffer layer greatly improves the crystalline quality and surface morphology of subsequently grown YxIn1-xN films. The piezoelectric response in films with x=0.09 and x=0.14 is observed using piezoresponse force microscopy. Theoretical calculations of the piezoelectric properties predict YxIn1−xN to have comparable piezoelectric properties to ScxAl1-xN.

  • 162.
    Tucker, Mark D
    et al.
    University of Sydney.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Guenette, Mathew C
    University of Sydney.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Bilek, Marcela M M
    University of Sydney.
    McKenzie, David R
    University of Sydney.
    Substrate orientation effects on the nucleation and growth of the M(n+1)AX(n) phase Ti2AlC2011In: JOURNAL OF APPLIED PHYSICS, ISSN 0021-8979, Vol. 109, no 1, p. 014903-Article in journal (Refereed)
    Abstract [en]

    The M(n+1)AX(n) (MAX) phases are ternary compounds comprising alternating layers of a transition metal carbide or nitride and a third "A-group" element. The effect of substrate orientation on the growth of Ti2AlC MAX phase films was investigated by studying pulsed cathodic arc deposited samples grown on sapphire cut along the (0001), (10 (1) over bar0), and (1 (1) over bar 02) crystallographic planes. Characterization of these samples was by x-ray diffraction, atomic force microscopy, and cross-sectional transmission electron microscopy. On the (10 (1) over bar0) substrate, tilted (10 (1) over bar8) growth of Ti2AlC was found, such that the TiC octahedra of the MAX phase structure have the same orientation as a spontaneously formed epitaxial TiC sublayer, preserving the typical TiC-Ti2AlC epitaxial relationship and confirming the importance of this relationship in determining MAX phase film orientation. An additional component of Ti2AlC with tilted fiber texture was observed in this sample; tilted fiber texture, or axiotaxy, has not previously been seen in MAX phase films.

  • 163.
    Tungasmita, Sukkaneste
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Järrendahl, Kenneth
    Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Enhanced quality of epitaxial AlN thin films on 6H-SiC by ultra-high-vacuum ion-assisted reactive dc magnetron sputter deposition2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 2, p. 170-172Article in journal (Refereed)
    Abstract [en]

    Epitaxial AlN thin films have been grown on 6H-SiC substrates by ultra-high-vacuum (UHV) ion-assisted reactive dc magnetron sputtering. The low-energy ion-assisted growth (E-i = 17-27 eV) results in an increasing surface mobility, promoting domain-boundary annihilation and epitaxial growth. Domain widths increased from 42 to 135 nm and strained-layer epitaxy was observed in this energy range. For E-i> 52 eV, an amorphous interfacial layer of AlN was formed on the SiC, which inhibited epitaxial growth. Using UHV condition and very pure nitrogen sputtering gas yielded reduced impurity levels in the films (O: 3.5 x 10(18) cm(-3)). Analysis techniques used in this study are in situ reflection high-energy electron diffraction, secondary-ion-mass spectroscopy, atomic-force microscopy, x-ray diffraction, and cross-section high-resolution electron microscopy. (C) 2000 American Institute of Physics. [S0003-6951(00)01802-7].

  • 164.
    Tungasmita, Sukkaneste
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Pulsed low-energy ion-assisted growth of epitaxial aluminum nitride layer on 6H-silicon carbide by reactive magnetron sputtering2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 6, p. 3551-3555Article in journal (Refereed)
    Abstract [en]

    Epitaxial aluminum nitride thin films have been grown on silicon carbide (6H-SiC) substrates by pulsed low-energy ion-assisted reactive magnetron sputter deposition (+5/-20 V of bias pulses), with ion-assisted energy (Ei)?22eV, under ultrahigh-vacuum conditions. Surface ion interactions during the negative bias pulse gave rise to enhanced surface mobility of adatoms with beneficial effects, which extended over the limit of ion repelling in the positive pulse as the film thickness increased. High-resolution electron microscopy shows that a large (>90 nm) AlN domain width can form on the substrate. Domain-boundary annihilation and domain suppression during film growth have been observed. The growth rate also increased by a factor of ~4 compared to growth conditions with no ion assistance (Ei=2eV) and by a factor of 2 from dc ion-assisted growth. This indicates that the supply of nitrogen is a limiting factor for AlN formation and that the reactivity of nitrogen is increased on the growing AlN film surface for pulse ion-assisted deposition. High-resolution x-ray diffraction shows a reduction in the full width at half maximum of the rocking curve from 1490 to 1180 arcsec when pulsed ions are used. The cathodoluminescence shows high intensity of near-band edge emissions at wavelengths of 206 (6.02 eV) and 212 nm (5.84 eV) at a measured temperature of 5 K, with relatively low defect and oxygen and carbon impurity related emission, which is indicative of a high quality electronic material. © 2002 American Institute of Physics.

  • 165.
    Tungasmita, Sukkaneste
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Järrendahl, Kenneth
    Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Low-energy-ion-assisted reactive sputter deposition of epitaxial AlN thin films on 6H-SiC2000In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 338-3, p. 1519-1522Article in journal (Refereed)
    Abstract [en]

    Epitaxial wurzite-structure AIN thin films have been grown on 6H-SiC substrates by ultra-high-vacuum (UHV) low-energy-ion-assisted reactive de magnetron sputtering. The quality of epitaxial AIN films is significantly improved by low-energy ion assistance (E-i = 17-27 eV), during reactive magnetron sputter growth on vicinal (3.5 degrees) 6H-SiC. The ion-assisted growth results in an increased surface mobility, which promotes domain boundary annihilation and epitaxial growth. This results in lateral expansion of column width. Thus, AIN films with domains as large as 40 nm at the interface to 6H-SiC can be realized. At film thickness above 100 nm, the column width expands to 100 nm. The crystal quality of the films is very good with low background impurities (O: 3.5x10 (18)cm(-3)).

  • 166.
    Tungasmita, Sukkaneste
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Seppänen, Timo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Growth of epitaxial (SiC)(x)(AlN)(1-x) thin films on 6H-SiC by ion-assisted dual magnetron sputter deposition2002In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 389-3, p. 1481-1484Article in journal (Refereed)
    Abstract [en]

    (SiC)(X)(AIN)(1-X) thin films have been grown epitaxially on vicinal 6H-SiC (0001) by low-energy ion assisted dual magnetron sputtering in UHV conditions. AES showed a decreasing Si and C content for an increasing magnetron power ratio, (P-Al/P-SiC). The epitaxial quality of the films was improved as the SiC fraction increased. Films containing less than 5% of Si and C show an evolution of domain width similar to the growth of pure AIN. HRXRD show a decreased c-axis lattice parameter for a film with composition of AINC(X) (0less than or equal toxless than or equal to0.1), indicating carbon substitution in AIN. CL spectra show defect-related peaks of similar to3.87 and similar to4.70 eV, corresponding to O and C impurities respectively as well as on un-identified peak at similar to3.40 eV.

  • 167. Valcheva, E
    et al.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Tungasmita, S
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Epitaxial growth and orientation of AlN thin films on Si(001) substrates deposited by reactive magnetron sputtering2006In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 100, no 12Article in journal (Refereed)
    Abstract [en]

    Epitaxial domain formation and textured growth in AlN thin films deposited on Si(001) substrates by reactive magnetron sputtering was studied by transmission electron microscopy and x-ray diffraction. The films have a wurtzite type structure with a crystallographic orientation relationship to the silicon substrate of AlN (0001) ∥Si (001). The AlN film is observed to nucleate randomly on the Si surface and grows three dimensionally, forming columnar domains. The in-plane orientation reveals four domains with their a axes rotated by 15° with respect to each other: AlN 〈11 2- 0〉 ∥Si [110], AlN 〈01 1- 0〉 ∥Si [110], AlN 〈11 2- 0〉 ∥Si [100], and AlN 〈01 1- 0〉 ∥Si [100] An explanation of the growth mode based on the large lattice mismatch and the topology of the substrate surface is proposed. © 2006 American Institute of Physics.

  • 168. Valcheva, E.
    et al.
    Dimitrov, S.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Haratizadeh, H.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Amano, H.
    Akasaki, I.
    Influence of well-width fluctuations on the electronic structure of GaN/AlxGa1-xN multiquantum wells with graded interfaces2007In: Acta Physica Polonica. A, ISSN 0587-4246, E-ISSN 1898-794X, Vol. 112, no 2, p. 395-400Article in journal (Refereed)
    Abstract [en]

    Experimental and computation results based on chemical composition assessment of metal-organic chemical vapour deposition grown undoped GaN/AlxGa1-xN multiquantum well structures in the low composition limit of x = 0.07 and wide wells demonstrate composition fluctuations in the barrier layers which lead to large-scale nonuniformities and inequivalence of the different wells. As a consequence the experimental photoluminescence spectra at low temperature show a double peak structure indicative of well-width fluctuations by one lattice parameter (2 monolayers).

  • 169. Valcheva, E.
    et al.
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Abrashev, M.V.
    Faculty of Physics, Sofia University, Sofia 1164, Bulgaria.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Goldys, E.M.
    Semiconductor Science and Technology Laboratories, Macquarie University, Sidney, NSW 2109, Australia.
    Beccard, R.
    Aixtron AG, D-52072 Aachen, Germany.
    Heuken, M.
    Aixtron AG, D-52072 Aachen, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Elimination of nonuniformities in thick GaN films using metalorganic chemical vapor deposited GaN templates2001In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 90, no 12, p. 6011-6016Article in journal (Refereed)
    Abstract [en]

    Thick hydride vapor phase epitaxial GaN layers are grown on metalorganic chemical vapor deposited GaN template layers as well as directly on sapphire, with the aim of investigating the effect of the template on the strain relaxation and spatial distribution of free carriers in the overgrown GaN films. Spatially resolved cross-sectional micro-Raman spectroscopy, cathodoluminescence, and transmission electron microscopy show improved crystalline quality for growth on metalorganic chemical vapor deposited GaN templates. The highly doped and highly defective near-substrate layer composed of columnar domains, typically present in hydride vapor phase epitaxial GaN films grown directly on sapphire, is absent in the layers grown on templates. Consequently, this results in elimination of the nonuniformities of free electron distribution, a lower residual free carrier concentration (<1017 cm-3), and improved strain relaxation. © 2001 American Institute of Physics.

  • 170.
    Valcheva, E.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Abrashev, M.V.
    Faculty of Physics, Sofia University, Sofia 1164, Bulgaria.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Goldys, E.M.
    Semiconductor Science and Technology Laboratories, Macquarie University, Sidney, NSW 2109, Australia.
    Beccard, R.
    Aixtron AG, D-52072 Aachen, Germany.
    Heuken, M.
    Aixtron AG, D-52072 Aachen, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Erratum: Elimination of nonuniformities in thick GaN films using metalorganic chemical vapor deposited GaN templates (Journal of Applied Physics (2001) 90 (6011))2002In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 91, no 10 I, p. 6778article id 6778Article in journal (Other academic)
    Abstract [en]

    [No abstract available]

  • 171. Valcheva, E.
    et al.
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Abrashev, M.V.
    Faculty of Physics, Sofia University, 5, J. Bourchier blvd., Sofia 1164, Bulgaria.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Goldys, E.M.
    Semiconductor Science and Technology Laboratories, Macquarie University, Sydney, NSW 2109, Australia.
    Beccard, R.
    Aixtron AG, D-52072 Aachen, Germany.
    Heuken, M.
    Aixtron AG, D-52072 Aachen, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Impact of MOCVD-GaN 'templates' on the spatial non-uniformities of strain and doping distribution in hydride vapour phase epitaxial GaN2001In: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 82, no 1-3, p. 35-38Article in journal (Refereed)
    Abstract [en]

    Thick HVPE-GaN layers are grown on Si-doped and undoped MOCVD-GaN 'template' layers as well as directly on sapphire, with the aim to investigate the effect of the MOCVD template on the strain relaxation and spatial distribution of free carriers in the overgrown HVPE films. Spatially resolved cross-sectional micro-Raman measurements, cathodoluminescence and transmission electron microscopy show improved crystalline quality resulting in elimination of the non-uniformities of electron distribution, a low free carrier concentration (< 1017 cm-3) as well as a significant strain relaxation effect. © 2001 Elsevier Science B.V.

  • 172. Valcheva, E.
    et al.
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Misfit defect formation in thick GaN layers grown on sapphire by hydride vapor phase epitaxy2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 80, no 9, p. 1550-Article in journal (Refereed)
    Abstract [en]

    [No abstract available]

  • 173. Valcheva, E
    et al.
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Nanopipes in thick GaN films grown at high growth rate2002In: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 194, no 2, p. 532-535Article in journal (Refereed)
    Abstract [en]

    In this work we illustrate and describe long propagating nanopipes in thick HVPE-GaN layers analysed by means of transmission electron microscopy. They are observed to behave like screw component threading dislocations, terminating surface steps by hexagonal pits, and thus leading to the possibility of spiral growth. The formation of a nanopipe is observed by trapping of a screw dislocation at a pinhole that opens in an empty core. The mechanism of formation of nanopipes is likely to be connected to the growth kinetics of screw dislocations in the early stages of growth of highly strained material.

  • 174.
    Valcheva, E
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tungasmita, Sukkaneste
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Svedberg, EB
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Interface structure of hydride vapor phase epitaxial GaN grown with high-temperature reactively sputtered AlN buffer2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 14, p. 1860-1862Article in journal (Refereed)
    Abstract [en]

    Thick hydride vapor phase epitaxy GaN layers have been grown on a-plane sapphire using high-temperature ion-assisted reactively sputtered AlN as a buffer layer. Transmission electron microscopy and atomic force microscopy were carried out to study the formation of the two interfaces sapphire/AlN and AlN/GaN, and their influence on the microstructure of both the buffer layer and the main GaN layer. It was demonstrated that the high-temperature reactively sputtered buffer layer provides a good alternative for hydride vapor phase epitaxy growth of GaN layers. In particular, the buffer promotes a specific interface ordering mechanism different from that observed on low-temperature buffers. (C) 2000 American Institute of Physics. [S0003-6951(00)00314-4].

  • 175.
    Wang, Suhao
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Sun, Hengda
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Ail, Ujwala
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Vagin, Mikhail
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O. Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Andreasen, Jens W.
    Technical University of Denmark Department of Energy Conversion and Storage Roskilde Denmark.
    Thiel, Walter
    Max‐Planck‐Institut für Kohlenforschung Mülheim an der Ruhr Germany.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Crispin, Xavier
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Fazzi, Daniele
    Max‐Planck‐Institut für Kohlenforschung Mülheim an der Ruhr Germany.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, Faculty of Science & Engineering.
    Thermoelectric Properties of Solution-Processed n-Doped Ladder-Type Conducting Polymers2016In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 28, no 48, p. 10764-Article in journal (Refereed)
    Abstract [en]

    Ladder-type “torsion-free” conducting polymers (e.g., polybenzimidazobenzophenanthroline (BBL)) can outperform “structurally distorted” donor–acceptor polymers (e.g., P(NDI2OD-T2)), in terms of conductivity and thermoelectric power factor. The polaron delocalization length is larger in BBL than in P(NDI2OD-T2), resulting in a higher measured polaron mobility. Structure–function relationships are drawn, setting material-design guidelines for the next generation of conducting thermoelectric polymers.

  • 176.
    Wilhelmsson, O.
    et al.
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Palmquist, J.-P.
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Lewin, E.
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Emmerlich, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Eklund, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Högberg, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Li, S.
    Ahuja, R.
    Uppsala University, Dept. of Physics, The Ångström Laboratory, P.O. Box 530, SE-751 21 Uppsala, Sweden.
    Eriksson, O.
    Uppsala University, Dept. of Physics, The Ångström Laboratory, P.O. Box 530, SE-751 21 Uppsala, Sweden.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Jansson, U.
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Deposition and characterization of ternary thin films within the Ti-Al-C system by DC magnetron sputtering2006In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 291, no 1, p. 290-300Article in journal (Refereed)
    Abstract [en]

    The formation of ternary compounds within the Ti-Al-C system was studied by magnetron sputtering for thin-film deposition and first-principles calculations for phase stability. As-deposited films were characterized with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (TEM). The hardness and Young's moduli of the material were studied by nanoindentation. Epitaxial and phase-pure films of Mn+1AXn phases Ti3AlC2 and Ti2AlC as well as the perovskite phase Ti3AlC were deposited on Al2O3(00l) wafers kept at temperatures between 800 and 900 °C. The only ternary phases observed at low temperatures (300 °C) were Ti3AlC and cubic (Ti,Al)C, the latter can be described as a metastable solid solution of Al in TiC similar to the more studied (Ti,Al)N system. The difficulties to form MAX phases at low substrate temperatures were attributed of requirement for a sufficient diffusivity to partition the elements corresponding to the relatively complex crystal structures with long c-axes. While MAX-phase synthesis at 800 °C is significantly lower than contemporary bulk sintering processes, a reduction of the substrate temperature towards 300 °C in the present thin-film deposition experiments resulted in stacking sequence variations and the intergrowth of (Ti,Al)C. © 2006 Elsevier B.V. All rights reserved.

  • 177.
    Willmann, Herbert
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Mayrhofer, P. H.
    University of Leoben, Austria.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Reiter, A. E.
    Balzers Ltd, Liechtenstein.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Mitterer, C.
    University of Leoben, Austria.
    Thermal stability of Al-Cr-N hard coatings2006In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 54, no 11, p. 1847-1851Article in journal (Refereed)
    Abstract [en]

    Heat treatment of arc-evaporated cubic Al0.7Cr0.3N hard coatings in Ar up to 1450 °C causes precipitation of AlN. The Cr-enriched matrix transforms into Cr via Cr2N under N2 release. These reactions are investigated by simultaneous thermal analysis, mass spectrometry, X-ray diffraction, and analytical transmission electron microscopy.

  • 178.
    Wongpanit, N.
    et al.
    Chulalongkorn Univ, Thailand.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tungasmita, S.
    Chulalongkorn Univ, Thailand.
    Etching behaviors of tunneling magnetoresistive (TMR) materials by ion beam etching system2018In: MATERIALS TODAY-PROCEEDINGS, ELSEVIER SCIENCE BV , 2018, Vol. 5, no 7, p. 15186-15191Conference paper (Refereed)
    Abstract [en]

    In data storage manufacturing, ion etching process is commonly chosen for the preparation of surface patterns, for example, under the read-write head of the hard disk drive (HDD) to form an air bearing surface (ABS). This read-write head consists of a multilayer thin film of different materials to form a tunneling magnetoresistive (TMR) device. In this work, we applied the Monte Carlo-based simulation package to calculate the etching yield of major materials in the HDD heads structure. The plasma characteristic in the industrial-size ion beam etching (IBE) system has been studied by the special plasma diagnostic probes. Effects of input parameters in IBE system such as incident beam angle, ion beam current and gas flow in the system were considered. Plasma characteristic can be obtained from plasma I-V curve characterization. The sputtering yields of materials were found maximum when an incident angle is about 70 degrees to the normal surface. The floating potential of plasma in the system with the ion/electron compensation from PBN is calculated. (C) 2018 Elsevier Ltd. All rights reserved.

  • 179.
    Xie, Mengyao
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Schubert, M.
    University of Nebraska, NE 68588 USA.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Stanishev, Vallery
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Chen, L. C.
    National Taiwan University, Taiwan.
    Schaff, W. J.
    Cornell University, NY 14853 USA.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Assessing structural, free-charge carrier, and phonon properties of mixed-phase epitaxial films: The case of InN2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 19, p. 195306-Article in journal (Refereed)
    Abstract [en]

    We develop and discuss appropriate methods based on x-ray diffraction and generalized infrared spectroscopic ellipsometry to identify wurtizte and zinc-blende polymorphs, and quantify their volume fractions in mixed-phase epitaxial films taking InN as an example. The spectral signatures occurring in the azimuth polarization (Muller matrix) maps of mixed-phase epitaxial InN films are discussed and explained in view of polymorphism (zinc-blende versus wurtzite), volume fraction of different polymorphs and their crystallographic orientation, and azimuth angle. A comprehensive study of the structural, phonon and free electron properties of zinc-blende InN films containing inclusions of wurtzite InN is also presented. Thorough analysis on the formation of the zinc-blende and wurtzite phases is given and the structural evolution with film thickness is discussed in detail. The phonon properties of the two phases are determined and discussed together with the determination of the bulk free-charge carrier concentration, and electron accumulation at the mixed-phase InN film surfaces.

  • 180.
    Xie, Mengyao
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Schubert, M.
    Department of Electrical Engeneering, University of Nebraska, Lincoln, Nebraska 68588.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Silva, A. G.
    Departamento de Fíısica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa Campus da Caparica, Caparica, Portugal.
    Santos, A.
    Departamento de Fíısica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa Campus da Caparica, Caparica, Portugal.
    Bundaleski, N.
    Departamento de Fíısica, Faculdade de Ciencias e Tecnologia, Universidade Nova de Lisboa Campus da Caparica, Caparica, Portugal.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hsiao, Ching-Lien
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Schaff, W.J.
    Department of Electrical and computer Engineering, Cornel University, Ithaca, New York, USA.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Structural, free-charge carrier and phonon properties of zinc-blende and wurtizte polymorphs in InN epitaxial layersManuscript (preprint) (Other academic)
    Abstract [en]

    We present a comprehensive study of the structural, phonon and free electron properties of zincblende InN films containing inclusion of wurtzite InN. Appropriate methods based on X-ray diffraction and Infrared spectroscopic ellipsometry to identify wurtizte and zinc-blende InN and quantify their phase ratio are developed and discussed. Thorough analysis on the formation of the cubic and wurtzite phases is presented and their evolution with film thickness is discussed in detail. The freecharge carrier and phonon properties of the two phases are discussed together with the determination of electron accumulation at the zinc-blende InN (001) and wurtzite (10̅11) surfaces.

  • 181.
    Yazdi, Gholamreza R.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Persson, Per O. Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gogova, Daniela
    Leibniz Institute for Crystal Growth, 12 489 Berlin, Germany.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Yakimova, Rosita
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Defect-free Single Crystal AlN Nanowires by Physical Vapor Transport GrowthManuscript (Other academic)
    Abstract [en]

    Growth by vapor-solid mechanism of AlN nanowires with a diameter in the range of 40-500nm and a length reaching 100 μm, resulting in a max aspect ratio of 600, is reported. Theobjects are obtained at 1750 oC and 850 mbar nitrogen pressure on 4H-SiC patternedsubstrates by sublimation epitaxy, which is a version of the physical vapor transport techniqueand provides a high growth rate. The nanowires are hexagonally shaped and perfectly alignedalong the 0001 direction with a small tilt given by the substrate vicinality. It is observed thatunder nitrogen excess a preferential growth along the c-axis of the wurtzite structure takesplace, and switches to lateral growth below some critical value of nitrogen pressure.Investigations by SEM, TEM, CL and Raman spectroscopy measurements were carried out. Itis shown that the nanowires consist of wurtzitic AlN with defect free crystal structure.Possible applications have been depicted.

  • 182.
    Yazdi, Gholamreza
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Gogova, D
    Leibniz Institute Crystal Growth.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Aligned AlN nanowires by self-organized vapor-solid growth2009In: NANOTECHNOLOGY, ISSN 0957-4484, Vol. 20, no 49, p. 495304-Article in journal (Refereed)
    Abstract [en]

    Highly oriented AlN single crystal nanowires with aspect ratio up to 600, diameter in the range of 40-500 nm, and 100 mu m lengths, have been synthesized via a vapor-solid growth mechanism. The results were obtained at 1750 degrees C and 850 mbar nitrogen pressure on vicinal SiC substrates pretreated by SiC sublimation epitaxy in order to attain distinguishable terraces. It was found that the nanowires change in thickness after they have reached a critical length, and this fact contributes to an understanding of the growth mechanism of AlN nanowires. The nanowires are hexagonally shaped and perfectly aligned along the [0001] direction with a small tilt given by the substrate vicinality. Under nitrogen excess a preferential growth along the c-axis of the wurtzite structure takes place while below some critical value of nitrogen pressure the growth mode switches to lateral. The AlN nanowires are shown to have a dislocation free wurtzite crystal structure. Some possible applications are discussed.

  • 183.
    Zangooie, S
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden JA Woollam Co Inc, Lincoln, NE 68508 USA.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hilfiker, JN
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden JA Woollam Co Inc, Lincoln, NE 68508 USA.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Microstructural and infrared optical properties of electrochemically etched highly doped 4H-SiC2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 87, no 12, p. 8497-8503Article in journal (Refereed)
    Abstract [en]

    Pores in porous 4H-SiC are found to propagate first nearly parallel with the basal plane and then gradually change plane of propagation towards the direction of the c axis. A similar anisotropy in pore propagation is found in porous 6H-SiC. A disordered phase is encountered at the interface between crystalline SiC and the pores. Formation of this phase was attributed to the etching conditions. Characterization of the material with nondestructive infrared spectroscopic ellipsometry in the photon energy range 0.062-0.62 eV provides average thickness and porosity in good agreement with electron microscopy observations. Anodization of SiC introduces remarkable changes to the reststrahlen band. A shallow minimum at 0.113 eV is attributed to the Berreman effect. In addition, a sharp peak at 0.126 eV is discussed to be related to the in-depth inhomogeneity and particle shape effects in the material. (C) 2000 American Institute of Physics. [S0021-8979(00)07312-6].

  • 184.
    Zangooie, S
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden JA Woollam Co Inc, Lincoln, NE 68508 USA.
    Persson, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Hilfiker, JN
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden JA Woollam Co Inc, Lincoln, NE 68508 USA.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Wahab, Qamar Ul
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Microstructural, optical and electronic investigation of anodized 4H-SiC2000In: Materials Science Forum, Vols. 338-342, 2000, Vol. 338-3, p. 537-540Conference paper (Refereed)
    Abstract [en]

    Pores in 4H porous SiC were found to propagate first nearly parallel with the basal plane and then gradually change plane of propagation from, e.g., (1 (1) over bar 04) to (1 (1) over bar 03) and (1 (1) over bar 02) etc. A disordered phase is formed at the interface between the pores and the crystalline SiC. Optical analysis of this phase reveals a more dielectric like nature of the material compared to crystalline SiC. The measured electrical resistivity at 296 K and 347 K were 2.9 x 10(8) . cm and 9.2 x 10(7) . cm, respectively.

  • 185.
    Zhou, Jie
    et al.
    Chinese Acad Sci, Peoples R China.
    Zha, Xian-Hu
    Chinese Acad Sci, Peoples R China.
    Yildizhan Özyar, Melike
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Xue, Jianming
    Peking Univ, Peoples R China.
    Liao, Meiyong
    NIMS, Japan.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Du, Shiyu
    Chinese Acad Sci, Peoples R China.
    Huang, Qing
    Chinese Acad Sci, Peoples R China.
    Two-Dimensional Hydroxyl-Functionalized and Carbon-Deficient Scandium Carbide, ScCxOH, a Direct Band Gap Semiconductor2019In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, no 2, p. 1195-1203Article in journal (Refereed)
    Abstract [en]

    Two-dimensional (2D) materials have attracted intense attention in nanoscience and nanotechnology due to their outstanding properties. Among these materials, the emerging family of 2D transition metal carbides, carbonitrides, and nitrides (referred to as MXenes) stands out because of the vast available chemical space for tuning materials chemistry and surface termination, offering opportunities for property tailoring. Specifically, semiconducting properties are needed to enable utilization in optoelectronics, but direct band gaps are experimentally challenging to achieve in these 2D carbides. Here, we demonstrate the fabrication of 2D hydroxyl-functionalized and carbon-deficient scandium carbide, namely, ScCxOH, by selective etching of a layered parent ScAI(3)C(3) compound. The 2D configuration is determined as a direct band gap semiconductor, with an experimentally measured band gap approximated at 2.5 eV. Furthermore, this ScCxOH-based device exhibits excellent photoresponse in the ultraviolet-visible light region (responsivity of 0.125 A/W at 360 nm/10 V, and quantum efficiency of 43%). Thus, this 2D ScCxOH direct band gap semiconductor may find applications in visible light detectors, photocatalytic chemistry, and optoelectronic devices.

  • 186.
    Zhu, Baiwei
    et al.
    Jonköping University, Sweden.
    Seifeddine, Salem
    Jonköping University, Sweden.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jarfors, Anders E. W.
    Jonköping University, Sweden.
    Leisner, Peter
    Jonköping University, Sweden; SP Technical Research Institute Sweden, Sweden.
    Zanella, Caterina
    Jonköping University, Sweden.
    A study of formation and growth of the anodised surface layer on cast Al-Si alloys based on different analytical techniques2016In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 101, p. 254-262Article in journal (Refereed)
    Abstract [en]

    This paper aims to investigate the mechanisms of formation and growth of the anodised surface layer on Al-Si castings by applying different analytical techniques such as optical microscopy, scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), and X-ray computer tomography (X-ray CT) scanning. Three different Al alloys with various Si content (2.43%, 3.53% and 5.45%) were investigated. Si particle morphological modification by Sr addition, as well as directional solidification, was used to vary the microstructural coarseness in a controlled manner to study the influence of these parameters on the growth behaviour of the oxide layer. This study observed residual unanodised Al phases trapped beneath or between Si particles in the oxide layer. It was found, depending on the geometry and morphology of Si particles, that Al can be shielded by Si particles and prevented from oxidising. (C) 2016 Elsevier Ltd. All rights reserved.

  • 187.
    Žukauskaitė, Agnė
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Tholander, Christopher
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Pališaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O. Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ben Sedrine, Nebiha
    Instituto Tecnológico e Nuclear, 2686-953 Sacavém and CFNUL, Lisbon 1649-003, Portugal.
    Tasnádi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    YxAl1-xN Thin Films2012In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, no 42, p. 422001-Article in journal (Refereed)
    Abstract [en]

    Reactive magnetron sputtering was used to deposit YxAl1-xN thin films, 0≤x≤0.22, onto Al2O3(0001) and Si(100) substrates. X-ray diffraction and analytical electron microscopy show that the films are solid solutions. Lattice constants are increasing with Y concentration, in agreement with ab initio calculations. Spectroscopic ellipsometry measurements reveal a band gap decrease from 6.2 eV (x=0) down to 4.9 eV (x=0.22). Theoretical investigations within the special quasirandom structure approach show that the wurtzite structure has the lowest mixingenthalpy for 0≤x≤0.75.

  • 188.
    Žukauskaitė, Agnė
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology. Fraunhofer Institute for Applied Solid State Physics, Freiburg, Germany.
    Tholander, Christopher
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Tasnádi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Pališaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O. Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Stabilization of Wurtzite Sc0.4Al0.6N in Pseudomorphic Epitaxial ScxAl1-xN/InyAl1-yN Superlattices2015In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 94, p. 101-110Article in journal (Refereed)
    Abstract [en]

    Pseudomorphic stabilization in wurtzite ScxAl1-xN/AlN and ScxAl1-xN/InyAl1-yN superlattices (x=0.2, 0.3, and 0.4; y=0.2-0.72), grown by reactive magnetron sputter epitaxy was investigated. X-ray diffraction and transmission electron microscopy show that in ScxAl1-xN/AlN superlattices the compressive biaxial stresses due to positive lattice mismatch in Sc0.3Al0.7N and Sc0.4Al0.6N lead to loss of epitaxy, although the structure remains layered. For the negative lattice mismatched In-rich ScxAl1-xN/InyAl1-yN superlattices a tensile biaxial stress promotes the stabilization of wurtzite ScxAl1-xN even for the highest investigated concentration x=0.4. Ab initio calculations with fixed in-plane lattice parameters show a reduction in mixing energy for wurtzite ScxAl1-xN under tensile stress when x≥0.375 and support the experimental results.

  • 189.
    Žukauskaitė, Agnė
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Wingqvist, Gunilla
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Pališaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O. Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Matloub, Ramin
    Ceramics Laboratory, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, SwitzerlandNational Laboratory, Oak Ridge, TN 37831, United States.
    Muralt, Paul
    Ceramics Laboratory, Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland.
    Kim, Yunseok
    Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Microstructure and Dielectric Properties of Piezoelectric Magnetron Sputtered w-ScxAl1-xN thin films2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 111, no 9, p. 093527-Article in journal (Refereed)
    Abstract [en]

    Piezoelectric wurtzite ScxAl1-xN (x=0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al2O3(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline quality. Samples grown at 400 °C possess true dielectric behavior with quite low dielectric losses and the leakage current is negligible. For ScAlN samples grown at 800 °C, the crystal structure is poor and leakage current is high. Transmission electron microscopy with energy dispersive x-ray spectroscopy mapping shows a mass separation into ScN-rich and AlN-rich domains for x≥0.2 when substrate temperature is increased from 400 to 800 °C. The piezoelectric response of epitaxial ScxAl1-xN films measured by piezoresponse force microscopy and double beam interferometry shows up to 180% increase by the addition of Sc up to x=0.2 independent of substrate temperature, in good agreement with previous theoretical predictions based on density-functional theory.

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