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  • 151.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Sridhara, S.G.
    Linnarsson, M.K.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Study of nitrogen, aluminium and boron incorporation in SiC layers grown by sublimation epitaxy2002In: J. Cryst. Growth, Vols. 237-239, 2002, Vol. 237-239, no 1-4 II, p. 1230-1234Conference paper (Refereed)
    Abstract [en]

    Sublimation epitaxy is a growth technique viable for SiC epilayer fabrication since the method is technologically simple, the growth rate is high (up to 100 µm/h) and the as-grown surfaces are very smooth. However, the remaining issues of purity and intentional doping control need to be studied and the behaviour understood before this method can be applied to device fabrication. We will show results of nitrogen, aluminium and boron incorporation in layers grown by sublimation epitaxy. The epilayers have been studied using electrical, secondary ion mass spectrometry and cathodoluminescence measurements as well as by low-temperature photoluminescence spectroscopy. Possible solutions to lower especially the nitrogen concentrations in epilayers are presented along with experimental results leading to epilayer net doping concentrations in the ND - NA ~ 1015cm-3 range. © 2002 Elsevier Science B.V. All rights reserved.

  • 152.
    Syväjärvi, Mikael
    et al.
    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.
    Tuominen, M
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Kakanakova-Georgieva, Anelia
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Macmillan, M F
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Wahab, Qamar Ul
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Growth of 6H and 4H-SiC by sublimation epitaxy1999In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 197, no 1-2, p. 155-162Article in journal (Refereed)
    Abstract [en]

      The epitaxial sublimation growth process of SiC has been investigated. Layers with specular surfaces and growth rates up to 2 mm/h have been obtained. No step bunching is observed by optical microscopy even on very thick layers which indicates a stable step growth mechanism. Under certain growth conditions the morphology degrades. The morphological stability is investigated and discussed in relation to the growth kinetics. Impurities in the epitaxial layers are investigated by secondary ion mass spectroscopy and low-temperature photoluminescence. The carrier concentration is measured by capacitance–voltage measurements. The structural quality of the grown material is improved compared to the substrate as shown by X-ray diffraction measurements.

     

  • 153.
    Tiwari, Ashutosh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Syväjärvi, MikaelLinköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Advanced Materials for Agriculture, Food and Environmental Safety2014Collection (editor) (Other academic)
    Abstract [en]

    The levels of toxic and microbial contamination in the food and environment are influenced by harvesting or slaughtering technologies and by the processes applied during food manufacture. With current cultivation methods, it is impossible to guarantee the absence of pesticides and pathogenic microorganisms in raw foods, both of plant and animal origin. Widespread and increasing incidence of foodborne diseases and the resulting social and economic impact on the world population have brought food and environmental safety to the forefront of ecological safety and public health concerns. The emerging field of advanced materials based on functional architectures offers potential solutions to some of the key performance challenges along with the improved sensitivity, longevity, stability, miniaturization and ruggedness, while reducing complexity and production cost. The overall purpose of this book is to generate new solutions to the technical challenges in easy and rapid detections of food toxicants, microorganisms and environmental pollutants. The book focuses on the role of advanced materials in the food, water and environmental applications.  The monitoring of harmful organisms and toxicants in water, food and beverages is mainly discussed in the respective chapters. The senior contributors write on the following topics:

    • Layered double hydroxides and environment
    • Corrosion resistance of aluminium alloys of silanes
    • New generation material for the removal of arsenic from water
    • Prediction and optimization of heavy clay products quality
    • Enhancement of physical and mechanical properties of fiber
    • Environment friendly acrylates latices
    • Nanoparticles for trace analysis of toxins
    • Recent development on gold nanomaterial as catalyst 
    • Nanosized metal oxide based adsorbents for heavy metal removal
    • Phytosynthesized transition metal nanoparticles- novel functional agents for textiles
    • Kinetics and equilibrium modeling
    • Magnetic nanoparticles for heavy metal removal
    • Potential applications of nanoparticles as antipathogens
    • Gas barrier properties of biopolymer based nanocomposites: Application in food packing
    • Application of zero-valent iron nanoparticles for environmental clean up

    Environmental application of novel TiO2 nanoparticles

  • 154.
    Tuominen, M.
    et al.
    Outokumpu Semitronic AB, Ekerö.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    MacMillan, M.F.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Investigation of domain evolution in sublimation epitaxy of SiC1998In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 193, no 1-2, p. 101-108Article in journal (Refereed)
    Abstract [en]

    High resolution X-ray diffractometry has been applied to study domain misorientation in SiC epi-layers grown by the sublimation epitaxy method. A pronounced effect of the growth conditions on the mosaicity of the epi-layer has been observed. The results are discussed in terms of domain evolution and structural changes during the epi-growth under different growth conditions.

  • 155.
    Tzalenchuk, Alexander
    et al.
    National Physics Lab, Teddington.
    Lara-Avila, Samuel
    Chalmers.
    Cedergren, Karin
    Chalmers.
    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.
    Kazakova, Olga
    National Physics Lab, Teddington.
    Janssen, T J B M
    National Physics Lab, Teddington.
    Moth-Poulsen, Kasper
    University of California Berkeley.
    Bjornholm, Thomas
    University of Copenhagen.
    Kopylov, Sergey
    University of Lancaster.
    Falko, Vladimir
    University of Lancaster.
    Kubatkin, Sergey
    Chalmers.
    Engineering and metrology of epitaxial graphene2011In: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 151, no 16, p. 1094-1099Article in journal (Refereed)
    Abstract [en]

    ere we review the concepts and technologies, in particular photochemical gating, which contributed to the recent progress in quantum Hall resistance metrology based on large scale epitaxial graphene on silicon carbide.

  • 156.
    Tzalenchuk, Alexander
    et al.
    National Physics Laboratory, Teddington, England .
    Lara-Avila, Samuel
    Chalmers.
    Kalaboukhov, Alexei
    Chalmers.
    Paolillo, Sara
    Politecn Milan.
    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.
    Kazakova, Olga
    National Physics Laboratory, Teddington, England .
    Janssen, T J B M
    National Physics Laboratory, Teddington, England .
    Falko, Vladimir
    University of Lancaster.
    Kubatkin, Sergey
    Chalmers.
    Towards a quantum resistance standard based on epitaxial graphene2010In: NATURE NANOTECHNOLOGY, ISSN 1748-3387, Vol. 5, no 3, p. 186-189Article in journal (Refereed)
    Abstract [en]

    The quantum Hall effect(1) allows the international standard for resistance to be defined in terms of the electron charge and Plancks constant alone. The effect comprises the quantization of the Hall resistance in two-dimensional electron systems in rational fractions of R-K = h/e(2) = 25 812.807 557(18) Omega, the resistance quantum(2). Despite 30 years of research into the quantum Hall effect, the level of precision necessary for metrology-a few parts per billion-has been achieved only in silicon and III-V heterostructure devices(3-5). Graphene should, in principle, be an ideal material for a quantum resistance standard(6), because it is inherently two-dimensional and its discrete electron energy levels in a magnetic field (the Landau levels(7)) are widely spaced. However, the precisions demonstrated so far have been lower than one part per million(8). Here, we report a quantum Hall resistance quantization accuracy of three parts per billion in monolayer epitaxial graphene at 300 mK, four orders of magnitude better than previously reported. Moreover, by demonstrating the structural integrity and uniformity of graphene over hundreds of micrometres, as well as reproducible mobility and carrier concentrations across a half-centimetre wafer, these results boost the prospects of using epitaxial graphene in applications beyond quantum metrology.

  • 157.
    Unéus, Lars
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Nakagomi, S
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Royal Inst Technol, SE-16440 Kista, Sweden Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan.
    Linnarsson, M
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Royal Inst Technol, SE-16440 Kista, Sweden Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan.
    Jensen, Mona
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Svensson, BG
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Ekedahl, Lars-Gunnar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lunstrom, I
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Royal Inst Technol, SE-16440 Kista, Sweden Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan.
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    The effect of hydrogen diffusion in p- and n-type SiC Schottky diodes at high temperatures2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 1419-1422Conference paper (Refereed)
    Abstract [en]

    We present here the effect of a hydrogen anneal at 600degreesC for Schottky sensor devices based on n- and p-type 4H SiC. The devices have gate contacts of Ta/Pt, or TaSix/Pt. The catalytic metal gate dissociates hydrogen and thus promotes diffusion of hydrogen atoms into the SiC, where the atoms will trap or react with different impurities, defects or surface states. This will change parameters such as the carrier concentrations, the defect density of the material or the surface resistivity at the SiC/SiO2 interface. The current-voltage and the capacitance-voltage characteristics were measured before and after annealing in hydrogen and oxygen containing atmosphere, and the results show a reversible effect in the I-V characteristics.

  • 158.
    Vahlberg, Cecilia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Yazdi, G. R.
    Khranovsky, V.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Uvdal, Kajsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Surface engineering of functional materials for biosensors2005In: IEEE Sensors 2005,2005, 2005, p. 504-Conference paper (Refereed)
  • 159.
    Vahlberg, Cecilia
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Yazdi, Gholam Reza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Khranovskyy, V.
    Petoral, Rodrigo Jr
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Uvdal, Kajsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics .
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Surface engineering of functional materials for biosensors2006In: IEEE SENSORS 2005,2005, Proceedings IEEE SENSORS: ieee.org , 2006, p. 504-Conference paper (Refereed)
  • 160.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Juillaguer, Sandrine
    CNRS and Université Montpellier 2, Laboratoire Charles Coulomb, Montpellier, France.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yakimova, Risitza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Cubic SiC formation on the C-face of 6H-SiC (0001) substrates2012In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 348, no 1, p. 91-96Article in journal (Refereed)
    Abstract [en]

    Nucleation and subsequent growth of cubic SiC (111) on Si- and C-faces of nominally on-axis 6H-SiC substrates was investigated.  More uniform nuclei and twin boundary distribution was observed when 3C-SiC was grown on the C-face. This was attributed to a lower critical supersaturation ratio. A new type of defects which appear as pits in the C-face 3C-SiC layers related to homoepitaxial  6H-SiC  spiral growth was found and described.  The evaluation  of the growth driving force for both polar faces showed that the homoepitaxial 6H-SiC spirals were not overgrown on the C-face  due to low maximum  supersaturation  ratio. The XRD ω-rocking  characterization shows a better structural quality of the 3C-SiC was grown on the Si-face, however on the C-face the uniformity over the whole sample was higher. Unintentional doping by N (~1016  cm-3) was slightly higher on the C-face while Al doping was higher (~1014  cm-3) on the Si-face of the grown material, similarly to the doping of hexagonal SiC polytypes.

  • 161.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Malinovskis, Paulius
    Vilnius University, Lithuania.
    Mekys, Algirdas
    Vilnius University, Lithuania.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Storasta, Jurgis
    Vilnius University, Lithuania.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Polytype Inclusions in Cubic Silicon Carbide2013In: Silicon Carbide and Related Materials 2012 / [ed] Alexander A. Lebedev, Sergey Yu. Davydov, Pavel A. Ivanov and Mikhail E. Levinshtein, Trans Tech Publications , 2013, Vol. 740-742, p. 335-338Conference paper (Refereed)
    Abstract [en]

    In this paper, we review our research on 6H-SiC polytype inclusions in 3C-SiC layers, which were grown on nominally on-axis 6H-SiC substrates using sublimation epitaxy. More than 90% coverage by 3C-SiC is typically achieved at growth temperature of 1775 degrees C. The main reason for the polytype inclusions to appear is local supersaturation non-uniformities over the sample surface which appear due to the temperature gradient and spiral growth nature of 6H-SiC. On the 6H-SiC spirals with small steps supersaturation is smaller and 3C-SiC nucleation and growth is diminished. Due to surface free energy and surface diffusion differences, polytype inclusions appear differently when 3C-SiC is grown on the Si- and C-faces. The 6H-SiC inclusions as well as twin boundaries act as neutral scattering centers and lower charge carrier mobility

  • 162.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Marinova, M.
    Aristotle University Thessaloniki.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Liljedahl, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Zoulis, G.
    CNRS.
    Lorenzzi, J.
    UCB Lyon 1.
    Ferro, G.
    UCB Lyon 1.
    Juillaguet, S.
    CNRS.
    Camassel, J.
    CNRS.
    K. Polychroniadis, E.
    Aristotle University Thessaloniki.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Effect of initial substrate conditions on growth of cubic silicon carbide2011In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 324, no 1, p. 7-14Article in journal (Refereed)
    Abstract [en]

    In order to analyze the epitaxial growth of cubic silicon carbide by sublimation epitaxy on different substrates, four different 6H-SiC substrate preparations were used: (i) as-received, (ii) re-polished, (iii) annealed and covered by silicon layer and (iv) with (1 1 1) 3C-SiC buffer layer. Almost 100% coverage and low twin density was achieved when grown on the buffer layer. The XRD and TEM characterizations show better material quality when the layer is grown directly on 6H-SiC substrates. Background doping evaluated by LTPL is in the range of 10(16) cm(-3) for N and 10(16) cm(-3) for Al in all grown layers.

  • 163.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Marinova, M.
    Aristotle University of Thessaloniki.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Mantzari, A.
    Aristotle University of Thessaloniki.
    Andreadou, A.
    Aristotle University of Thessaloniki.
    Lorenzzi, J.
    UMR-CNRS.
    Ferro, G.
    UMR-CNRS.
    Polychroniadis, E.K.
    Aristotle University of Thessaloniki.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Sublimation Growth and Structural Characterization of 3C-SiC on Hexagonal and Cubic SiC Seeds2010In: Materials Science Forum, Vols. 645-648, Transtec Publications; 1999 , 2010, Vol. 645-648, p. 175-178Conference paper (Refereed)
    Abstract [en]

    Epitaxial growth of cubic silicon carbide on 6H-SiC substrates, and 6H-SiC substrates with (111) 3C-SiC buffer layer, deposited by vapour liquid solid mechanism, was compared. The morphological details of the grown layers were studied by optical microscopy and their microstructure by transmission electron microscopy. The influence of the substrate on the nucleation of 3C-SiC, the initial homoepitaxial 6H-SiC nucleation before 3C-SiC as well as the formation of defects, are discussed.

  • 164.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Marinova, M.
    Department of Physics, Aristotle University of Thessaloniki, GR54124, Thessaloniki, Greece.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Polychroniadis, E. K.
    Department of Physics, Aristotle University of Thessaloniki, GR54124, Thessaloniki, Greece..
    Yakimova, Risitza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Polytype transformation and structural characteristics of 3C-SiC on 6H-SiC substrates2014In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 395, p. 109-115Article in journal (Refereed)
    Abstract [en]

    The 3C-SiC (111) was grown on on-axis 6H-SiC substrates in a temperature interval ranging from 1675oC where 3C-SiC nucleated, to 1825oC where coverage of the substrate by 3C-SiC was  nearly  100%.  The  6H-  to  3C-SiC  transformation  was  not  abrupt  and  two  different transitions could be observed. The first one occurs before or during 3C-SiC nucleation and consists  of 6H-,  3C-, 15R-SiC  and other  unresolved  stacking  sequences.  The second  one appears due to 6H-SiC and 3C-SiC competition  during the growth and results in non flat needle-like interface. A proposed model elucidates connection between four-fold twins nucleating at the 6H-/3C-SiC interface and the formation of depressions at the surface of the 3C-SiC layer.

  • 165.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Marinova, Maya
    Aristotle University of Thessaloniki.
    Hens, Philip
    University Erlangen-Nuremberg.
    Wellmann, Peter
    University Erlangen-Nuremberg.
    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.
    Nucleation Control of Cubic Silicon Carbide on 6H- Substrates2012In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 12, no 1, p. 197-204Article in journal (Refereed)
    Abstract [en]

    The nucleation of cubic (3C) SiC on on-axis 6H-SiC was investigated in the temperature range 1500–1775 °C by the technique of sublimation epitaxy. We have studied two different cases: (i) the initial homoepitaxial growth of 6H-SiC followed by nucleation of 3C-SiC and (ii) nucleation of homoepitaxial 6H-SiC islands. The supersaturation in the growth cell was calculated using the modeled source to substrate temperature difference. We show that, at low temperature and supersaturation, growth of 6H-SiC commences in spiral growth mode, which prepares the surface for 3C-SiC nucleation. Provided the supersaturation is high enough, the 3C-SiC nucleates as two-dimensional islands on terraces of the homoepitaxial 6H-SiC. Detailed structural study indicates that the 3C-SiC began to grow on defect free surfaces. From the experimental and modeling results, we show that the growth parameter window for 3C-SiC is rather narrow. Deviation from it can result in 6H-SiC growth in spiral or 2D-nucleation mode, which suggests the importance of knowledge of supersaturation.

  • 166.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Mekys, A.
    Institute of Applied Research, Vilnius University, LT 10222, Vilnius, Lithuania.
    Malinovskis, P.
    Institute of Applied Research, Vilnius University, LT 10222, Vilnius, Lithuania.
    Juillaguer, Sandrine
    CNRS and Université Montpellier 2, Laboratoire Charles Coulomb, Montpellier, France.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Storasta, J.
    Institute of Applied Research, Vilnius University, LT 10222, Vilnius, Lithuania.
    Yakimova, Risitza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Impact of extended defects on Hall and magnetoresistivity effects in cubic silicon carbide2012In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, no 22, p. 225102-Article in journal (Refereed)
    Abstract [en]

    From magnetoresistivity effect measurements the carrier mobility at room- temperature is 200 cm2/Vs in heteroepitaxially grown 3C-SiC on 6H-SiC by sublimation epitaxy. The main scattering mechanisms are found to be scattering by neutral impurities at low temperature and by phonons at higher temperature. The carrier concentration is in the range of 1016  cm-3, which corresponds to the concentration of residual doping by nitrogen acquired  from  photoluminescence  measurements.  Using  magnetoresistance  and  Hall mobility data we have created a simple model which quantifies the volume of the samples influenced by extended defects. A higher doping near extended defects is either not present in the samples or might be screened by the electrostatic field created by these defects.

  • 167.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Mekys, A.
    Institute of Applied Research, Vilnius University, LT 10222, Vilnius, Lithuania.
    Malinovskis, P.
    Institute of Applied Research, Vilnius University, LT 10222, Vilnius, Lithuania.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Storasta, J.
    Institute of Applied Research, Vilnius University, LT 10222, Vilnius, Lithuania.
    Yakimova, Rositza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Influence of twin boundary orientation on magnetoresistivity effect in free standing 3C–SiC2012In: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 74, p. 203-205Article in journal (Refereed)
    Abstract [en]

    Free standing 3C–SiC (111) samples with differently oriented twin boundaries were prepared using on-axis and slightly off-axis 6H–SiC substrates. The orientation of twin boundaries causes either an enhancement or suppression of the magnetoresistance mobility. The origin of carrier mobility difference is attributed to the specific structure of these defects. The height of the barriers created by twin boundaries was found to be 0.2 eV.

  • 168.
    Vasiliauskas, Remigijus
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Beshkova, Milena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Two-dimensional nucleation of cubic and 6H silicon carbide2009In: ECSCRM2008,2008, Materials Science Forum Vols. 615-617: Trans Tech Publications , 2009, p. 189-192Conference paper (Refereed)
    Abstract [en]

    The initial stage of heteroepitaxial growth of 3C-SiC and homoepitaxial growth of 6H-SiC on nominal 6H-SiC on-axis substrates has been studied. Before 3C-SiC starts to nucleate, 6H-SiC grows in a step-flow growth mode due to a slight off-orientation of the substrate surface already at about 1500oC. In the 1650-1700oC temperature interval 3C-SiC nucleates as 2D islands. A distance away from the 3C-SiC island 6H-SiC grows in step-flow mechanism. In the vicinity of the 3C-SiC islands the 6H-SiC growth steps start to change direction and even split into two steps with the equal height of 0.5 nm, which is approaching the unit cell size of cubic SiC. When the supersaturation is lower in comparison with the conditions for 3C-SiC growth, there is only formation of 6H-SiC, i.e. homoepitaxial growth. The growth mode of 6H-SiC is dependent on temperature. At the lowest temperature there is spiral growth while at higher temperature 2D nucleation is preferred.

  • 169.
    Virojanadara, Chariya
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . 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, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Johansson, Leif
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Zakharov, A A
    Lund University.
    Balasubramanian , T
    Lund University.
    Homogeneous large-area graphene layer growth on 6H-SiC(0001)2008In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 78, no 24, p. 245403-Article in journal (Refereed)
    Abstract [en]

    Homogeneous large-area graphene monolayers were successfully prepared ex situ on 6H-SiC(0001). The samples have been studied systematically and the results are compared with those from a sample cut from the same wafer and prepared by in situ heating. The formation of smaller graphene flakes was found on the in situ prepared sample, which is in line with earlier observations. Distinctly different results are observed from the ex situ graphene layers of different thicknesses, which are proposed as a guideline for determining graphene growth. Recorded C 1s spectra consisted of three components: bulk SiC, graphene (G), and interface (I), the latter being a 6 root 3 layer. Extracted intensity ratios of G/I were found to give a good estimate of the thickness of graphene. Differences are also revealed in micro low energy electron diffraction images and electron reflectivity curves. The diffraction patterns were distinctly different from a monolayer thickness up to three layers. At a larger thickness only the graphitelike spot was visible. The electron reflectivity curve showed a nice oscillation behavior with kinetic energy and as a function of the number of graphene layers. The graphene sheets prepared were found to be very inert and the interface between the substrate and the layer(s) was found to be quite abrupt. No free Si could be detected in or on the graphene layers or at the interface.

  • 170.
    Virojanadara, Chariya
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Johansson, Leif
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Zakharov, A.A.
    Balasubramanian, T.
    Single Layer Graphene Growth on 6H-SiC(0001)2009Conference paper (Refereed)
  • 171.
    Virojanadara, Chariya
    et al.
    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.
    Osiecki, Jacek
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Uhrberg, Roger
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics.
    Johansson, Leif
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Zakharov, A A
    Lund University.
    Substrate orientation: A way towards higher quality monolayer graphene growth on 6H-SiC(0001)2009In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 603, no 15, p. L87-L90Article in journal (Refereed)
    Abstract [en]

    The influence of substrate orientation on the morphology of graphene growth on 6H-SiC(0 0 0 1) was investigated using low-energy electron and scanning tunneling microscopy (LEEM and STM). Large area monolayer graphene was successfully furnace-grown on these substrates. Larger terrace widths and smaller step heights were obtained on substrates with a smaller mis-orientation from on-axis (0.03 degrees) than on those with a larger (0.25 degrees). Two different types of a carbon atom networks, honeycomb and three-for-six arrangement, were atomically resolved in the graphene monolayer. These findings are of relevance for various potential applications based on graphene-SiC structures.

  • 172. Vouroutzis, N
    et al.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Stoemenos, J
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Characteristics of planar defects in shallow trenches related to the presence of micropipes2003In: Materials Science Forum, Vols. 433-436, 2003, Vol. 433-4, p. 277-280Conference paper (Refereed)
    Abstract [en]

    The similarities of the trenches related with micropipes observed in 4H-SiC layers formed by sublimation epitaxy are compared with the line-shaped pits observed by optical microscopy in the vicinity of closing micropipes in 4H-SiC epilayers grown by the CVD method. The disturbance of the step-flow along the trenches and the related extended defects are discussed.

  • 173.
    Vouroutzis, N
    et al.
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Aristotle Univ Thessaloniki, Dept Phys, GR-54006 Thessaloniki, Greece.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Jacobson, H
    Stoemenos, J
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Aristotle Univ Thessaloniki, Dept Phys, GR-54006 Thessaloniki, Greece.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Behavior of micropipes during growth in 4H-SiC2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 395-398Conference paper (Refereed)
    Abstract [en]

    The disturbance of the growth steps in SiC epitaxy and the formation of stacking faults (SFs) in the vicinity of a micropipe were studied by Atomic Force Microscopy and Transmission Electron Microscopy. Shallow trenches are observed in front of the micropipes due to the distortion of the growth steps towards of the micropipe. The trenches are related with extended (1 (1) over bar 00) type SFs bounded by 1/6 < 11 (2) over bar1 > partial dislocations. These results are also supported by synchrotron X-ray topography.

  • 174. Wagner, M.
    et al.
    Mustafa, E.
    Hahn, S.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Jang, S.
    Sakwe, S.A.
    Wellmann, P.J.
    Contactless Electrical Defect Characterization and Topography of a-Plane Grown Epitaxial Layers2007In: ECSCRM 2006,2006, Material Science Forum, vol. 556-557: Trans Tech Publications , 2007, p. 327-Conference paper (Refereed)
    Abstract [en]

      

  • 175.
    Wellmann, Peter
    et al.
    University of Erlangen-Nuremberg, Germany.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kneissel, Michael
    Technical University of Berlin, Germany .
    Wang, Rongmin
    Beijing University of Aeronaut and Astronaut, China.
    Preface to selected papers from EMRS 2011 Symposium Q: Engineering of wide bandgap semiconductor materials for energy saving2012In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 522, p. 1-1Article in journal (Other academic)
  • 176.
    Wilhelm, Martin
    et al.
    University of Erlangen-Nuremberg, Erlangen, Germany.
    Kaiser, Michl
    University of Erlangen-Nuremberg, Erlangen, Germany.
    Jakubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Y.
    Technical University of Denmark, Lyngby, Denmark.
    Ou, H.
    Technical University of Denmark, Lyngby, Denmark.
    Wellmann, P.
    University of Erlangen-Nuremberg, Erlangen, Germany.
    Photoluminescence topography of fluorescent SiC and its corresponding source crystals2013In: Silicon Carbide and Related Materials 2012 / [ed] Alexander A. Lebedev, Sergey Yu. Davydov, Pavel A. Ivanov and Mikhail E. Levinshtein, Trans Tech Publications Inc., 2013, Vol. 740-742, p. 421-424Conference paper (Refereed)
    Abstract [en]

    The preparation and application of co-doped polycrystalline SiC as source in sublimation growth of fluorescent layers is a complex topic. Photoluminescence topographies of luminescent 6H-SiC layers and their corresponding source crystals have been studied in order to investigate the dependence of the epitaxial growth on the source material. It is shown that the homogeneity concerning the dopant incorporation and the layer luminescence intensity does not depend on the characteristics of the PVT grown source material. Therefore co-doped polycrystalline SiC is a promising source material in fast sublimation growth of luminescent 6H-SiC.

  • 177.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kakanakova-Gueorguie, Anelia
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jacobson, Henrik
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Virojanadara, Chariya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Johansson, Leif
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Effect of High Temperature Annealing on Surface and Bulk Characteristics of 4H-SiC2001In: Proc. of the 43rd Electronic Material Conference, 2001Conference paper (Refereed)
  • 178.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Jacobson, H
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Virojanadara, Chariya
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Johansson, Leif
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Impact of the initial surface conditions on defect appearance in 4H-SiC epilayers2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 283-286Conference paper (Refereed)
    Abstract [en]

    Effect of surface irregularities on defect nucleation and development in thick epitaxial layers of 4H-SiC has been investigated. It has been shown that during growth extended defects may undergo transformation and thus stacking faults can be formed, which is favored in thicker layers (e.g. 50mum). Network of misfit dislocations appears if the initial surface has a certain critical roughness and a lower surface energy. Evidence has been presented that well ordered graphite layer might form on the substrates during the preheating stage prior to growth via sublimation.

  • 179.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Yazdi, Gholamreza R.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gueorguiev, Gueorgui K.
    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.
    Sublimation growth of AlN crystals: Growth mode and structure evolution2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 281, no 1, p. 81-86Article in journal (Refereed)
    Abstract [en]

    The aim of this study has been to realize growth conditions suitable for seeded sublimation growth of AlN and to understand the relationship between external growth parameters and the initial stages of growth with respect to growth mode and structure evolution. Close space sublimation growth geometry has been used in a RF-heated furnace employing high-purity graphite coated by TaC with a possibility to change the growth environment from C- to Ta-rich. Influence of certain impurities on the initially formed crystallites with respect to their shape, size and population has been considered. It is shown that some impurity containing vapor molecules may act as transport agents and suppliers of nitrogen for the AlN growth. SiC seeds, both bare and with MOCVD AlN buffer, have been employed. By varying the process conditions we have grown crystals with different habits, e.g. from needles, columnar- and plate-like, to freestanding quasi-bulk material. The growth temperature ranged 1600–2000 °C whereas the optimal external nitrogen pressure varied from 200 to 700 mbar. There is a narrow parameter window in the relationship temperature–pressure for the evolution of different structural forms. Growth modes with respect to process conditions are discussed.

  • 180.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Lebedev, A.A.
    Ivanov, A.M.
    Strokan, N.B.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    The limit of SiC detector energy resolution in ions spectrometry2006In: Materials Science Forum, Vols. 527-529, 2006, Vol. 527-529, p. 1477-1480Conference paper (Refereed)
  • 181.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology.
    Advances in SiC thick epilayer growth for power devices and sensors2005In: WASMPE 2005,2005, 2005, p. 26-28Conference paper (Refereed)
  • 182.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Liquid Phase Epitaxy of SiC2007In: Liquid Phase Epitaxy of Electronic, Optical and Optoelectronic Materials / [ed] Peter Capper, Michael Mauk, UK: Wiley , 2007, 1, p. 179-202Chapter in book (Other academic)
    Abstract [en]

      Liquid-Phase Epitaxy (LPE) is a technique used in the bulk growth of crystals, typically in semiconductor manufacturing, whereby the crystal is grown from a rich solution of the semiconductor onto a substrate in layers, each of which is formed by supersaturation or cooling. At least 50% of growth in the optoelectronics area is currently focussed on LPE.

    This book covers the bulk growth of semiconductors, i.e. silicon, gallium arsenide, cadmium mercury telluride, indium phosphide, indium antimonide, gallium nitride, cadmium zinc telluride, a range of wide-bandgap II-VI compounds, diamond and silicon carbide, and a wide range of oxides/fluorides (including sapphire and quartz) that are used in many industrial applications. A separate chapter is devoted to the fascinating field of growth in various forms of microgravity, an activity that is approximately 30-years old and which has revealed many interesting features, some of which have been very surprising to experimenters and theoreticians alike.

    • Covers the most important materials within the field
    • The contributors come from a wide variety of countries and include both academics and industrialists, to give a balanced treatment
    • Builds-on an established series known in the community
    • Highly pertinent to current and future developments in telecommunications and computer-processing industries.
  • 183.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Ciechonski, Rafal
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Wahab, Qamar Ul
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Growth of device quality 4H-SiC by high velocity epitaxy2004In: Materials Science Forum, Vols. 457-460, 2004, Vol. 457-460, p. 201-204Conference paper (Refereed)
    Abstract [en]

    Thick (>20 μm) 4H-SiC layers in doping range of low 1015-1016 cm-3 were grown by sublimation epitaxy at a growth rate of similar to50 mum/hour. Two inch 25 μm thick layers were fabricated with standard thickness deviation of 3.77%. Effect of important process parameters on the material grade has been discussed. The Schottky diodes processed on this material sustained 900V reverse voltage at a current of 1.7 x 10-8 A, while measured on MOS capacitors the interface state density was as low as similar to6-9 x 1010 cm-2.

  • 184.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Jacobsson, Henrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Raback, P.
    Råback, P., Center for Scientific Computing, P.O. Box 405, FIN-02101 Espoo, Finland.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Growth of silicon carbide: Process-related defects2001In: Appl. Surf. Sci., Vol. 184, 2001, Vol. 184, no 1-4, p. 27-36Conference paper (Refereed)
    Abstract [en]

    This paper reviews the present understanding of defect formation and development in relation to process conditions in 4H-SiC crystal growth and epitaxy. The polytype uniformity during seeded sublimation growth of SiC boules has been discussed. Insight into different structural imperfections has been attempted. The role of the temperature distribution, as well as of the quality of seed/crystal interface in the occurrence of grown-in defects has been demonstrated. Micropipe termination by liquid-phase deposition along with defect evolution in subsequently grown layers due to rough interface has been addressed. Finally, a relation between extended morphological defects in thick (50-100 µm) 4H-SiC epitaxial layers and local stress in the material has been suggested. Optimised growth conditions to reduce the overall defect density have been proposed. © 2001 Elsevier Science B.V. All rights reserved.

  • 185.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Jacobsson, Henrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Raback, R
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Okmet AB, S-17824 Ekero, Sweden Ctr Comp Sci, FIN-02101 Espoo, Finland Okmet Ltd, FIN-01301 Vantaa, Finland.
    Vehanen, A
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Okmet AB, S-17824 Ekero, Sweden Ctr Comp Sci, FIN-02101 Espoo, Finland Okmet Ltd, FIN-01301 Vantaa, Finland.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Polytype stability in seeded sublimation growth of 4H-SiC boules2000In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 217, no 3, p. 255-262Article in journal (Refereed)
    Abstract [en]

    Process conditions for stable single polytype growth of 4H-SiC boules via a seeded sublimation technique have been developed. Reproducible results can be obtained in a narrow temperature interval around 2350 degrees C and on the C-face of 4H-SiC seeds. Evidence is presented that during the initial stage of growth, morphological instabilities may occur resulting in structural defects. A solution is proposed based on the experimental findings, i.e. the first regions of growth ought to be carried out at a low supersaturation (growth rate similar to 100 mu m/h) until a proper growth front has developed. (C) 2000 Elsevier Science B.V. All rights reserved.

  • 186.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Okunev, AO
    Udal'tsov, VE
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Orientation-dependent defect formation in silicon carbide epitaxial layers2003In: Materials Science Forum, Vols. 433-436, 2003, Vol. 433-4, p. 281-284Conference paper (Refereed)
    Abstract [en]

    Thick SiC epitaxial layers have been grown by sublimation on different initial surfaces in the range of 1800-2200degreesC. Evidences have been obtained that independently of the polytype and the surface polarity, there exists a transition region between the substrate and the epilayer in which the crystal structure is highly disturbed either by formation of misfit dislocations, predominantly in growth on vicinal (off-axis) surfaces or by domain boundaries and polytype transformation during growth on atomically flat (on-axis) surfaces. The transition layer thickness may vary from 15 to 50 mum and it seems to depend on the growth rate.

  • 187.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jacobson, Henrik
    Linköping University, Department of Social and Welfare Studies. Linköping University, Faculty of Educational Sciences.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Some aspects of extended defects formation and their reduction in silicon carbide crystals2003In: Recent research developments in materials science & engineering. Vol. 1, pt. 1 / [ed] S. G. Pandalai, Kerala, India: Trans Research Network , 2003, 1, p. 619-646Chapter in book (Other academic)
  • 188.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jacobsson, H
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Rendakova, S
    Dmitriev, V
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Defect evolution in SiC sublimation epitaxy layers grown on LPE buffers with reduced micropipe density2001In: Materials Research Society Symposium Proceedings, Vol. 640, 2001, p. H2.1.1-H2.1.6Conference paper (Refereed)
  • 189.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Stress related morphological defects in SiC epitaxial layers2001In: Diam. Relat. Mater., Vol. 10, 2001, Vol. 10, no 3-7, p. 1246-1250Conference paper (Refereed)
    Abstract [en]

    Morphological defects have been studied on thick 4H-SiC layers being grown with high growth rate (100 µm/h) by sublimation epitaxy. While the surface morphology of such layers is generally specular and featureless, extended defects are observed to emanate from some obstacles. The length of the defects can vary between 60 and 950 µm and the defect can occur at different stages of growth. Evidence shows that these defects occur due to localised stress present during the epitaxial growth. The causes for the defects can be greatly reduced by improving the structural quality of the substrate material. © 2001 Elsevier Science B.V. All rights reserved.

  • 190.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pons, M.
    Institut National Polytechnique de Grenoble.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Influence of gravity on defect formation in homoepitaxial layers of SiC grown by sublimation2001In: ESA SP-454, 2001, p. 381-Conference paper (Refereed)
    Abstract [en]

    4H-SiC homoepitaxial growth has been performed by sublimation process. The basic transport mechanism and dynamics of the growth has been studied. Both, experiment and numerical modelling have been performed. It has been shown that high growth rate (0.1 mm/hour) can be obtained when the overall structural quality is very good and the surface morphology is excellent. However, deep level defects associated with impurities have been observed. Evidence has been obtained that the impurity incorporation may be influenced by gravity-induced growth instabilities. At this stage, numerical modelling of the growth process has been performed considering only macroscopic features. For the present experimental configuration, preliminary results reveal that the influence of microgravity is low. The macroscopic transfer phenomena leading to the growth of the crystal are mainly diffusive. The future is to design specific experiments involving higher temperature difference between source and seed, as well as to consider microscopic growth phenomena.

  • 191.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Rendakova, S
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden TDI Inc, Gaithersburg, MD 20877 USA Howard Univ, MSRCE, Washington, DC 20059 USA.
    Dimitriev, VA
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden TDI Inc, Gaithersburg, MD 20877 USA Howard Univ, MSRCE, Washington, DC 20059 USA.
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Micropipe healing in liquid phase epitaxial growth of SiC2000In: Materials Science Forum, Vols. 338-342, Trans Tech Publications Inc., 2000, Vol. 338-3, p. 237-240Conference paper (Refereed)
    Abstract [en]

    In this study we demonstrate the feasibility of micropipe reduction in SiC commercial wafers by using liquid phase epitaxial (LPE) growth. We have studied the stability of the micropipe healing by performing hot KOH etching and growing thick (40-50 mum) layer with sublimation epitaxy at temperature higher than that used for the LPE growth. Experimental evidences have been collected by means of different techniques and a phenomenological model for micropipe healing is proposed.

  • 192.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Vasiliauskas, Remigijus
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Progress in 3C-SiC growth and novel applications2012In: Materials Science Forum Vol 711, Trans Tech Publications Inc., 2012, Vol. 711, p. 3-10Conference paper (Refereed)
    Abstract [en]

    Recent research efforts in growth of 3C-SiC are reviewed. Sublimation growth is addressed with an emphasis on the enhanced understanding of polytype stability in relation to growth conditions, such as supersaturation and Si/C ratio. It is shown that at low temperature/supersaturation spiral 6H-SiC growth is favored, which prepares the surface for 3C-SiC nucleation. Provided the supersaturation is high enough, 3C-SiC nucleates as two-dimensional islands on terraces of the homoepitaxial 6H-SiC. Effect of different substrate surface preparations is considered. Typical extended defects and their electrical activity is discussed. Finally, possible novel applications are outlined.

  • 193.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Virojanadara, Chariya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Gogova, Daniela
    Leibniz Institute for Crystal Growth, Berlin, Germany.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Siche, D.
    Leibniz Institute for Crystal Growth, Berlin, Germany.
    Larsson, Krister
    Department of Materials Chemistry, Uppsala University, Uppsala, Sweden.
    Johansson, Leif
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Analysis of the Formation Conditions for Large Area Epitaxial Graphene on SiC Substrates2010In: SILICON CARBIDE AND RELATED MATERIALS 2009, PTS 1 AND 2 / [ed] Bauer, AJ; Friedrichs, P; Krieger, M; Pensl, G; Rupp, R; Seyller, T, Trans Tech Publications Inc., 2010, Vol. 645-648, p. 565-568Conference paper (Refereed)
    Abstract [en]

    We are aiming at understanding the graphene formation mechanism on different SiC polytypes (6H, 4H and 3C) and orientations with the ultimate goal to fabricate large area graphene (up to 2 inch) with controlled number of monolayers and spatial uniformity. To reach the objectives we are using high-temperature atmospheric pressure sublimation process in an inductively heated furnace. The epitaxial graphene is characterized by ARPES, LEEM and Raman spectroscopy. Theoretical studies are employed to get better insight of graphene patterns and stability. Reproducible results of single layer graphene on the Si-face of 6H and 4H-SiC polytypes have been attained. It is demonstrated that thickness uniformity of graphene is very sensitive to the substrate miscut.

  • 194.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Vouroutzis, N
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Stoemenos, J
    Morphological features related to micropipe closing in 4H-SiC2005In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 98, no 3, p. 34905-Article in journal (Refereed)
    Abstract [en]

    The closing of micropipes during sublimation epitaxy has been studied. Shallow trenches are formed along the direction of the step-flow growth in the vicinity of closed micropipes. The trenches are related to a serious disturbance of the flowing steps and the formation of stacking faults in the (0001) basal plane as well as in the (1 1- 00) plane. A micropipe closes when the speed of the growth steps is higher than the spiral growth around the micropipe. This mechanism is related to a bending of the micropipe along the trench and the progressive emission of elementary screw dislocations along the trench. The morphology of the disturbed steps at the trenches and the related defects have been studied by transmission electron microscopy and atomic force microscopy. Supporting evidences are presented with optical micrographs from etched epilayers. Image forces, which are developed by the growth steps, stabilize the bending of the micropipes. The limitation of the bending is also discussed. © 2005 American Institute of Physics.

  • 195.
    Yakimova, Rositsa
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yazdi, Gholam Reza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Nguyen, Son Tien
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Ivanov, Ivan Gueorguiev
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Sun, S.
    Tompa, G.
    Kuznetsov, A.
    Svensson, B.
    Optical and Morphological Features of Bulk and Homoepitaxial ZnO2006In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 39, p. 247-256Article in journal (Refereed)
    Abstract [en]

    ZnO substrate crystals from two different sources, and epitaxial layers have been studied by SEM, AFM, photoluminescence (T=2-135K) and EPR. Although fabricated by the same growth principle, i.e. the hydrothermal technique, the substrates differ in terms of purity and structural quality. In the PL spectra of all samples the dominating emission originates from the donor bound exciton (BE) recombination positioned at about 3361 meV. The temperature dependence of the spectra confirms the assignment of the free exciton emission in the purest sample, the line at 3376 meV evolves into a broad peak at higher temperatures, probably including both A and B excitons. Another FE-related emission appears as a shoulder on the high-energy side of FEA,B above 40 K. It is expected and associated with the crystal-field split-off counterpart of the valence band. Free-exciton related emission in the less pure sample can only be seen if the temperature is above 45 K. At T=135K all bound excitons are quenched and the spectrum in both samples consists of the free exciton no-phonon lines and their replicas. However, the emission from the pure samples is several orders of magnitude stronger than that from the other sample, which indicates strong non-radiative quenching of the excitons in the latter sample. The EPR measurements reveal a possible scenario of impurity re-arrangement, e.g. annealing at 950 °C may dissociate existing complexes and release Fe as isolated ions. The AFM and SEM investigations of an epilayer grown by MOCVD on one of the studied substrates have indicated growth instabilities and structural irregularities, thus pointing to the need for substrate quality and epitaxial process optimization.

  • 196.
    Yakimova, Rositsa
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yazdi, Gholam Reza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Sritirawisarn, N.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Structure Evolution of 3C-SiC on Cubic and Hexagonal Substrates2006In: Materials Science Forum, Vols. 527-529, 2006, Vol. 527-529, p. 283-286Conference paper (Refereed)
  • 197.
    Yazdi, G. Reza
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Vasiliauskas, Remigijus
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Zakharov, A.
    Maxlab, Lund University, S-22100 Lund, Sweden.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Yakimova, Risitza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Growth of quality graphene on cubic silicon carbideManuscript (preprint) (Other academic)
    Abstract [en]

    The growth of epitaxial graphene was performed on the Si-face of 4H-SiC, 6H-SiC and 3C-SiC substrates by Si sublimation of SiC in Ar atmosphere at a temperature of 2000oC. Graphene surface morphology and thickness have been evaluated using low-energy electron microscopy (LEEM)  and  atomic  force  microscopy   (AFM).  Large  homogeneous   areas  of  graphene monolayers (over 50x50 μm2) have been successfully grown on 3C-SiC substrates. Differences in the morphology of graphene layers, grown on different SiC polytypes, are related to a large extent to minimization of the terrace surface energy during the step bunching process. The uniformity  of  Si  sublimation  is  a  decisive  factor  for  obtaining  large  area  homogeneous graphene. It is also shown that better quality graphene is grown on 3C-SiC substrates with smoother  surface,  because of less pronounced  step bunching  and lower distribution  of step heights on polished surface.

  • 198.
    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.

  • 199.
    Yazdi, Gholamreza
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Beckers, Manfred
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Giuliani, Finn
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . 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.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Freestanding AlN single crystals enabled by self-organization of 2H-SiC pyramids on 4H-SiC substrates2009In: APPLIED PHYSICS LETTERS, ISSN 0003-6951, Vol. 94, no 8, p. 082109-Article in journal (Refereed)
    Abstract [en]

    A sublimation-recondensation process is presented for high quality AlN (0001) crystals at a high growth rate by employing 4H-SiC substrates with a predeposited epilayer. It is based on the coalescence of well oriented AlN microrods, which evolve from the apex of 2H-SiC pyramids grown out of hexagonal pits formed by thermal etching of the substrate during a temperature ramp up. This process yields stress-free 120-mu m-thick AlN single crystals with a dislocation density as low as 2x10(6) cm(-2).

  • 200.
    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.

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