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  • 101.
    Scajev, P.
    et al.
    Vilnius University, Lithuania.
    Onufnjevs, P.
    Vilnius University, Lithuania .
    Manolis, G.
    Vilnius University, Lithuania.
    Karaliunas, M.
    Vilnius University, Lithuania.
    Nargelas, S.
    Vilnius University, Lithuania.
    Jegenyes, N.
    University Claude Bernard Lyon 1, France.
    Lorenzzi, J.
    University Claude Bernard Lyon 1, France.
    Ferro, G.
    University Claude Bernard Lyon 1, France.
    Beshkova, Milena
    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.
    Syvajärvi, 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.
    Kato, M.
    Nagoya Institute of Technology, Japan.
    Jarasionas, K.
    Vilnius University, Lithuania.
    On applicability of time-resolved optical techniques for characterization of differently grown 3C-SiC crystals and heterostructures2012In: HETEROSIC and WASMPE 2011 / [ed] Daniel Alquier, Trans Tech Publications Inc., 2012, Vol. 711, p. 159-163Conference paper (Refereed)
    Abstract [en]

    We applied a number of time-resolved optical techniques for investigation of optical and photoelectrical properties of cubic SiC grown by different technologies on different substrates. The excess carriers were injected by a short laser pulse and their dynamics was monitored by free-carrier absorption, light-induced transient grating, and photoluminescence techniques in a wide excitation range. Combining an optical and electrical probe beam delay, we found that free carrier lifetimes in differently grown layers vary from few ns up to 20 mu s. Temperature dependences of carrier diffusivity and lifetime revealed a pronounced carrier trapping in thin sublimation grown layers. In free-standing layers and thick sublimation layers, the ambipolar mobility was found the highest (120 cm(2)/Vs at room temperature). A linear correlation between the room-temperature band edge emission and carrier lifetime in differently grown layers was attributed to defect density, strongly dependent on the used growth conditions.

  • 102.
    Schimmel, Saskia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology. University of Erlangen, Germany.
    Kaiser, Michl
    University of Erlangen, Germany.
    Hens, Philip
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jokubavicius, Valdas
    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.
    Sun, Jianwu
    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.
    Ou, Yi Yu
    Technical University of Denmark, Lyngby.
    Ou, Hai Yan
    Technical University of Denmark, Lyngby.
    Linnarsson, Margareta K.
    KTH Royal Institute of Technology, Sweden.
    Wellmann, Peter
    University of Erlangen, Germany.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Step-flow growth of fluorescent 4H-SiC layers on 4 degree off-axis substrates2013In: 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. 185-188Conference paper (Refereed)
    Abstract [en]

    Homoepitaxial layers of fluorescent 4H-SiC were grown on 4 degree off-axis substrates by sublimation epitaxy. Luminescence in the green spectral range was obtained by co-doping with nitrogen and boron utilizing donor-acceptor pair luminescence. This concept opens possibilities to explore green light emitting diodes using a new materials platform.

  • 103.
    Schimmel, Saskia
    et al.
    University of Erlangen, Germany .
    Kaiser, Michl
    University of Erlangen, Germany .
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ou, Yiyu
    Technical University of Denmark, Lyngby.
    Hens, Philip
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Linnarsson, Margareta K.
    School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Sun, Jianwu
    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.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Wellmann, Peter
    University of Erlangen, Germany .
    The role of defects in fluorescent silicon carbide layers grown by sublimation epitaxy2014In: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 56, no 1, p. 012002-Article in journal (Refereed)
    Abstract [en]

    Donor-acceptor co-doped SiC is a promising light converter for novel monolithic all-semiconductor white LEDs due to its broad-band donor-acceptor pair luminescence and potentially high internal quantum efficiency. Besides sufficiently high doping concentrations in an appropriate ratio yielding short radiative lifetimes, long nonradiative lifetimes are crucial for efficient light conversion. The impact of different types of defects is studied by characterizing fluorescent silicon carbide layers with regard to photoluminescence intensity, homogeneity and efficiency taking into account dislocation density and distribution. Different doping concentrations and variations in gas phase composition and pressure are investigated.

  • 104.
    Shi, Yuchen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Höjer, Pontus
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yazdi, Gholamreza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Sun, Jianwu W.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    A comparative study of high-quality C-face and Si-face 3C-SiC(1 1 1) grown on off-oriented 4H-SiC substrates2019In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 52, no 34Article in journal (Refereed)
    Abstract [en]

    We present a comparative study of the C-face and Si-face of 3C-SiC(111) grown on off-oriented 4H-SiC substrates by the sublimation epitaxy. By the lateral enlargement method, we demonstrate that the high-quality bulk-like C-face 3C-SiC with thickness of ~1 mm can be grown over a large single domain without double positioning boundaries (DPBs), which are known to have a strongly negative impact on the electronic properties of the material. Moreover, the C-face sample exhibits a smoother surface with one unit cell height steps while the surface of the Si-face sample exhibits steps twice as high as on the C-face due to step-bunching. High-resolution XRD and low temperature photoluminescence measurements show that C-face 3C-SiC can reach the same high crystalline quality as the Si-face 3C-SiC. Furthermore, cross-section studies of the C- and Si-face 3C-SiC demonstrate that in both cases an initial homoepitaxial 4H-SiC layer followed by a polytype transition layer are formed prior to the formation and lateral expansion of 3C-SiC layer. However, the transition layer in the C-face sample is extending along the step-flow direction less than that on the Si-face sample, giving rise to a more fairly consistent crystalline quality 3C-SiC epilayer over the whole sample compared to the Si-face 3C-SiC where more defects appeared on the surface at the edge. This facilitates the lateral enlargement of 3C-SiC growth on hexagonal SiC substrates.

  • 105.
    Shi, Yuchen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Zakharov, Alexei A.
    MAXIV Laboratory, Lund, Sweden.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yazdi, Gholamreza Reza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Elimination of step bunching in the growth of large-area monolayer and multilayer graphene on off-axis 3CSiC (111)2018In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 140, p. 533-542Article in journal (Refereed)
    Abstract [en]

    Multilayer graphene has exhibited distinct electronic properties such as the tunable bandgap for optoelectronic applications. Among all graphene growth techniques, thermal decomposition of SiC is regarded as a promising method for production of device-quality graphene. However, it is still very challenging to grow uniform graphene over a large-area, especially multilayer graphene. One of the main obstacles is the occurrence of step bunching on the SiC surface, which significantly influences the formation process and the uniformity of the multilayer graphene. In this work, we have systematically studied the growth of monolayer and multilayer graphene on off-axis 3CSiC(111). Taking advantage of the synergistic effect of periodic SiC step edges as graphene nucleation sites and the unique thermal decomposition energy of 3CSiC steps, we demonstrate that the step bunching can be fully eliminated during graphene growth and large-area monolayer, bilayer, and four-layer graphene can be controllably obtained on high-quality off-axis 3CSiC(111) surface. The low energy electron microscopy results demonstrate that a uniform four-layer graphene has been grown over areas of tens of square micrometers, which opens the possibility to tune the bandgap for optoelectronic devices. Furthermore, a model for graphene growth along with the step bunching elimination is proposed.

    The full text will be freely available from 2020-08-24 11:11
  • 106.
    Shtepliuk, I
    et al.
    Kiev, Ukraine.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lashkarev, G
    Kiev, Ukraine.
    Khomyak, V.
    Chernivtsi, Ukraine.
    Lazorenko, V
    Kiev, Ukraine.
    Ievtushenko, A
    Kiev, Ukraine.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jokubavicius, Valdas
    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, Semiconductor Materials. Linköping University, The Institute of Technology.
    Electrical properties of n-Zn0.94Cd0.06O/p-SiC heterostructures2013In: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 81, p. 72-77Article in journal (Refereed)
    Abstract [en]

    We report the low-temperature (250 °C) fabrication of n-ZnCdO/p-SiC heterostructures by direct current magnetron sputtering (DC MS) technique. As-grown heterostructures exhibit diode characteristics: current–voltage measurements showed a typical rectifying characteristic of a p–n junction and the presence of series resistance. It is found that the turn-on voltage of heterostructures depends on the acceptor concentration in p-SiC. Via Cd doping of ZnO the energy barrier for holes can be lowered, which promotes the hole injection from the p-type layer to the n-type layer as well as favors the radiative recombination in the n-ZnCdO layer.

  • 107. Shulpina, IL
    et al.
    Savkina, NS
    Shuman, VB
    Ratnikov, VV
    Syväjärvi, Mikael
    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.
    X-ray diffraction analysis of epigrowth on porous 4H-SiC substrates2005In: Materials Science Forum, Vols. 483-485, 2005, Vol. 483, p. 265-268Conference paper (Refereed)
    Abstract [en]

    The methods of X-ray topography and diffractometry have been applied to characterize the structure of epilayers grown on porous layers. Two geometrical configurations of defects determined to be stacking faults (SF) were revealed: i) with the images of triangular shape with the edge size 560 gm along the <, 10-10>, directions, ii) linear shape along the [11-20] direction. The sources of SFs are located within the epilayer and start from the epilayer / porous layer interface. We propose that the source of SFs is connected with graphitization of porous layer at the temperature of epitaxy.

  • 108. Shulpina, I.L.
    et al.
    Savkina, N.S.
    Shuman, V.B.
    Ratnikov, V.V.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    X-Ray Diffraction Analysis of Epigrowth on Porous SiC Substrates2005In: Materials Science Forum, Vols. 483-485, 2005, Vol. 483-485, p. 265-268Conference paper (Refereed)
  • 109.
    Strokan, N.B.
    et al.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021, Russian Federation.
    Ivanov, A.M.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021, Russian Federation.
    Lebedev, A.A.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021, Russian Federation.
    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 .
    Measurement of micrometer diffusion lengths by nuclear spectrometry2005In: Semiconductors (Woodbury, N.Y.), ISSN 1063-7826, E-ISSN 1090-6479, Vol. 39, no 12, p. 1394-1398Article in journal (Refereed)
    Abstract [en]

    A method for determination of diffusion lengths in the range 0.5-50 µm, which corresponds to carrier lifetimes in the nanosecond range, is suggested A calibrated nonequilibrium charge is injected into the base of the reverse-biased diode structure. The injection is provided by alpha particles generated by natural decay in the single-particle counting mode. The nuclear spectrometry technique is used to measure the amount of charge that diffused across the base to the boundary of the electric-field region. The loss of charge during the diffusion is calculated as a function of the depth of alpha particle penetration beyond the electric-field region. The derived power-law functions make it possible to relate the diffusion length with the exponent and numerical factor that describes the loss of charge. The experiment is performed with lightly doped 4H-SiC epitaxial films. © 2005 Pleiades Publishing, Inc.

  • 110.
    Strokan, N.B.
    et al.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021, Russian Federation.
    Ivanov, A.M.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021, Russian Federation.
    Lebedev, A.A.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, St. Petersburg, 194021, Russian Federation.
    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 .
    The limiting energy resolution of SiC detectors in ion spectrometry2005In: Semiconductors (Woodbury, N.Y.), ISSN 1063-7826, E-ISSN 1090-6479, Vol. 39, no 12, p. 1420-1425Article in journal (Refereed)
    Abstract [en]

    The Monte Carlo method is used to simulate the complete stopping of a particles in SiC. A histogram of energy losses in nuclear-scattering events is obtained. The energy-loss spectrum has the characteristic asymmetric shape with the line full width at the half-maximum FWHMnucl ˜ 4. 22 keV. The final shape of the spectral line is obtained by a convolution with the Gaussian function that describes the contribution of the ionization and noise fluctuations (originated in the detector and instrumentation) to the signal. The resulting value of FWHM for the line is equal to 8.75 keV (at a noise variance of 1.7 keV). The experimental energy resolution of the detectors was found to be poorer than the calculated value by a factor of 2. It is established that the losses of charge during its transport in the detector bulk are insignificant, so that the discrepancy between the calculated and experimental values of the resolution should be attributed to the nonoptimal design of the detector window. © 2005 Pleiades Publishing, Inc.

  • 111. Strokan, N.B.
    et al.
    Ivanov, A.M.
    Savkina, N.S.
    Lebedev, A.A.
    Kozlovski, V.V.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Investigation of the SiC transistor and diode nuclear detectors at 8MeV proton irradiation2005In: Materials Science Forum, Vols. 483-485, 2005, Vol. 483-485, p. 1025-1028Conference paper (Refereed)
  • 112.
    Strokan, N.B.
    et al.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021, Russian Federation.
    Ivanov, A.M.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021, Russian Federation.
    Savkina, N.S.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021, Russian Federation.
    Lebedev, A.A.
    Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021, Russian Federation.
    Kozlovskii, V.V.
    Kozlovskii, V.V., St. Petersburg Polytech. University, Politekhnicheskaya ul. 29, St. Petersburg, 195251, Russian Federation.
    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 .
    Radiation resistance of transistor- and diode-type SiC detectors irradiated with 8-MeV protons2004In: Semiconductors (Woodbury, N.Y.), ISSN 1063-7826, E-ISSN 1090-6479, Vol. 38, no 7, p. 807-811Article in journal (Refereed)
    Abstract [en]

    Nuclear-particle detectors based on SiC with a structure composed of an n+-type substrate, a p-type epitaxial layer, and a Schottky barrier are studied. Structures with a ~10-µm-thick 6H-SiC layer exhibit transistor properties, whereas those with a ~30-µm-thick 4H-SiC layer exhibit diode properties. It is established that a more than tenfold amplification of the signal is observed in the transistor-type structure. The amplification is retained after irradiation with 8-MeV protons with a dose of at least 5 × 1013 cm-2, in this case, the resolution is =10%. Amplification of the signal was not observed in the structures of diode type. However, there were diode-type detectors with a resolution of ˜3%, which is acceptable for a number of applications, even after irradiation with the highest dose of 2 × 1014 cm-2. © 2004 MAIK "Nauka/Interperiodica".

  • 113.
    Strokan, N.B.
    et al.
    A. F. Ioffe Phys.-Tekhnical Inst., Polytekhnichaskaja 26, 194021 St. Petersburg, Russian Federation.
    Ivanov, A.M.
    A. F. Ioffe Phys.-Tekhnical Inst., Polytekhnichaskaja 26, 194021 St. Petersburg, Russian Federation.
    Savkina, N.S.
    A. F. Ioffe Phys.-Tekhnical Inst., Polytekhnichaskaja 26, 194021 St. Petersburg, Russian Federation.
    Strelchuk, A.M.
    A. F. Ioffe Phys.-Tekhnical Inst., Polytekhnichaskaja 26, 194021 St. Petersburg, Russian Federation.
    Lebedev, A.A.
    A. F. Ioffe Phys.-Tekhnical Inst., Polytekhnichaskaja 26, 194021 St. Petersburg, Russian Federation.
    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 .
    Detection of strongly and weakly ionizing radiation by triode structure based on SIC films2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 93, no 9, p. 5714-5719Article in journal (Refereed)
    Abstract [en]

    The detection of strongly and weakly ionizing radiation by triode structure based on silicon carbide (SiC) films was discussed. The possibility of alpha particle spectrometry in spite of slow carrier transport via diffusion was demonstrated. Analysis showed that the signal generated by weakly ionizing radiation incident on a film had low amplitude.

  • 114.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ivanov, Ivan Gueorguiev
    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.
    Yakimova, Rositsa
    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.
    Considerably long carrier lifetimes in high-quality 3C-SiC(111)2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 25, p. 252101-Article in journal (Refereed)
    Abstract [en]

    As a challenge and consequence due to its metastable nature, cubic silicon carbide (3C-SiC) has only shown inferior material quality compared with the established hexagonal polytypes. We report on growth of 3C-SiC(111) having a state of the art semiconductor quality in the SiC polytype family. The x-ray diffraction and low temperature photoluminescence measurements show that the cubic structure can indeed reach a very high crystal quality. As an ultimate device property, this material demonstrates a measured carrier lifetime of 8.2 mu s which is comparable with the best carrier lifetime in 4 H-SiC layers. In a 760-mu m thick layer, we show that the interface recombination can be neglected since almost all excess carriers recombines before reaching the interface while the surface recombination significantly reduces the carrier lifetime. In fact, a comparison of experimental lifetimes with numerical simulations indicates that the real bulk lifetime in such high quality 3C-SiC is in the range of 10-15 mu s.

  • 115.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Gao, L.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Booker, Ian Don
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xinyu
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Hofmann, J.P.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Hensen, E.J.M.
    Department of Chemical Engineering and Chemistry, Eindhoven University of of Technology, P.O. Box 513, Eindhoven, Netherlands.
    Linnarsson, M.
    School of Information and Communication Technology, KTH Royal Institute of Technology, Kista, Sweden.
    Wellmann, P.
    Department of Materials Science 6, University of of Erlangen-Nuremberg, Martensstr. 7, Erlangen, Germany.
    Ramiro, I.
    Instituto de Energía Solar, Universidad Politécnica de Madrid, E.T.S.I. Telecomunicación, Av. De la Complutense 30, Madrid, Spain.
    Marti, A.
    Instituto de Energía Solar, Universidad Politécnica de Madrid, E.T.S.I. Telecomunicación, Av. De la Complutense 30, Madrid, Spain.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Solar driven energy conversion applications based on 3C-SiC2016In: Materials Science Forum, Trans Tech Publications Ltd , 2016, Vol. 858, p. 1028-1031Conference paper (Refereed)
    Abstract [en]

    There is a strong and growing worldwide research on exploring renewable energy resources. Solar energy is the most abundant, inexhaustible and clean energy source, but there are profound material challenges to capture, convert and store solar energy. In this work, we explore 3C-SiC as an attractive material towards solar-driven energy conversion applications: (i) Boron doped 3C-SiC as candidate for an intermediate band photovoltaic material, and (ii) 3C-SiC as a photoelectrode for solar-driven water splitting. Absorption spectrum of boron doped 3C-SiC shows a deep energy level at ~0.7 eV above the valence band edge. This indicates that boron doped 3C-SiC may be a good candidate as an intermediate band photovoltaic material, and that bulk like 3C-SiC can have sufficient quality to be a promising electrode for photoelectrochemical water splitting. © 2016 Trans Tech Publications, Switzerland.

  • 116.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Jokubavicius, Valdas
    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.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Juillaguet, S.
    Université Montpellier 2, France.
    Camassel, J.
    CNRS, Montpellier, France.
    Kamiyama, S.
    Meijo University, Nagoya, Japan.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Room temperature luminescence properties of fluorescent SiC as white light emitting diode medium2012In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 522, p. 33-35Article in journal (Refereed)
    Abstract [en]

    The high quantum efficiency of donor–acceptor-pair emission in N and B co-doped 6H–SiC opens the way for SiC to constitute as an efficient light-emitting medium for white light-emitting diodes. In this work, we evidence room temperature luminescence in N and B co-doped 6H–SiC fluorescent material grown by the Fast Sublimation Growth Process. Three series of samples, with eight different N and B doping levels, were investigated. In most samples, from photoluminescence measurements a strong N–B donor–acceptor-pair emission band was observed at room temperature, with intensity dependent on the nitrogen pressure in the growth chamber and boron doping level in the source. Low temperature photoluminescence spectra showed that N bound exciton peaks exhibited a continuous broadening with increasing N2 pressure during the growth, unambiguously indicating an opportunity to control the N doping in the epilayer by conveniently changing the N2 pressure. Finally, the crystal quality of the N and B doped 6H–SiC was evaluated by X-ray diffraction measurements. The ω rocking curves of (0006) Bragg diffractions from the samples grown with lower and higher N2 pressure show almost the same value of the full width at half maximum as that collected from the substrate. This suggests that the N and B doping, which is expected to give rise to an efficient donor–acceptor-pair emission at room temperature, does not degrade the crystal quality.

  • 117.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kamiyama, Satoshi
    Meijo University, Nagoya, Japan.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Peyre, H.
    Universite Montpellier 2, France .
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Juillaguet, S.
    Universite Montpellier 2, France .
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Fluorescent silicon carbide as an ultraviolet-to-visible light converter by control of donor to acceptor recombinations2012In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, no 23, p. 235107-Article in journal (Refereed)
    Abstract [en]

    As an alternative to the conventional phosphors in white LEDs, a donor and acceptor co-doped fluorescent 6H-SiC can be used as an ultraviolet-to-visible light converter without any need of rare-earth metals. From experimental data we provide an explanation to how light can be obtained at room temperature by a balance of the donors and acceptors. A steady-state recombination rate model is used to demonstrate that the luminescence in fluorescent SiC can be enhanced by controlling the donor and acceptor doping levels. A doping criterion for optimization of this luminescence is thus proposed.

  • 118.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kamiyama, Satoshi
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Wellmann, Peter
    University of Erlangen-Nuremberg, Erlangen, Germany.
    Liljedahl, Rickard
    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.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Microsecond carrier lifetimes in bulk-like 3C-SiC grown by sublimation epitaxy2013In: 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. 315-318Conference paper (Refereed)
    Abstract [en]

    High quality bulk-like 3C-SiC were grown on on-axis (0001) 6H-SiC substrate by sublimation epitaxy. The microwave photoconductivity decay mapping measurements revealed that this material shows considerable long carrier lifetimes varied from 3.519 to 7.834 mu s under the injection level of 3.5x10(12) cm(-2), which are comparable with the best carrier lifetimes in 4H-SiC layers. The mapping of high resolution x-ray diffraction obtained from the same region shows that smaller carrier lifetimes seem to correspond to the larger FWHM values and vice versa. This shows that long carrier lifetime obtained in 3C-SiC is due to the improvement of the crystal quality.

  • 119.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kamiyama, Satoshi
    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.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Effect of surface and interface recombination on carrier lifetime in 6H-SiC layers2013In: SILICON CARBIDE AND RELATED MATERIALS 2012, Trans Tech Publications , 2013, Vol. 740-742, p. 490-493Conference paper (Refereed)
    Abstract [en]

    Carrier lifetimes in 6H-SiC epilayers were investigated by using numerical simulations and micro-wave photoconductivity decay measurements. The measured carrier lifetimes were significantly increasing with an increased thickness up to 200 mu m while it stays almost constant in layers thicker than 200 mu m. From a comparison of the simulation and experimental results, we found that if the bulk lifetime in 6H-SiC is around a few microseconds, both the surface recombination and interface recombination influence the carrier lifetime in layers with thickness less than 200 mu m while only the surface recombination determines the carrier lifetime in layers with thickness more than 200 mu m. In samples with varying thicknesses, a bulk lifetime tau(B) = 2.93 mu s and carrier diffusion coefficient D= 2.87 cm(2)/s were derived from the linear fitting of reciprocal lifetime vs reciprocal square thickness.

  • 120.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Robert, T.
    Universite Montellier 2, France .
    Andreadou, A.
    Aristotle University of Thessaloniki, Greece .
    Mantzari, A.
    Aristotle University of Thessaloniki, Greece .
    Jokubavicius, Valdas
    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.
    Camassel, J.
    Universite Montellier 2, France.
    Juillaguet, S.
    Universite Montpellier 2, France.
    Polychroniadis, E. K.
    Aristotle University of Thessaloniki, Greece.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Shockley-Frank stacking faults in 6H-SiC2012In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 111, p. 113527-Article in journal (Refereed)
    Abstract [en]

    We report on Shockley-Frank stacking faults (SFs) identified in 6H-SiC by a combination of low temperature photoluminescence (LTPL) and high resolution transmission electron microscopy (TEM). In the faulted area, stacking faults manifested as large photoluminescence emissions bands located in between the 6H-SiC signal (at ∼2.99 eV) and the 3C-SiC bulk-like one (at ∼2.39 eV). Each of the stacking fault related emission band had a four-fold structure coming from the TA, LA, TO, and LO phonon modes of 3C-SiC. Up to four different faults, with four different thickness of the 3C-SiC lamella, could be observed simultaneously within the extent of the laser excitation spot. From the energy of the momentum-conservative phonons, they were associated with excitonic energy gaps at Egx1 = 2.837 eV, Egx2 = 2.689 eV, Egx3 = 2.600 eV and Egx4 = 2.525 eV. In the same part where low temperature photoluminescence was performed, high resolution transmission electron microscopy measurements revealed stacking faults which, in terms of the Zhdanov notation, could be recognized as SFs (3, 4), (3, 5), (3, 6), (3, 7), (3, 9), (3, 11), (3, 16) and (3, 22), respectively. Among them stacking fault (3, 4) was the most common one, but a faulted region with a (4, 4) 8H-SiC like sequence was also found. Using a type II 6H/3C/6H quantum-well model and comparing with experimental results, we find that the photoluminescence emissions with excitonic band gaps at 2.837 eV (Egx1), 2.689 eV (Egx2), 2.600 eV (Egx3) and 2.525 eV (Egx4) come from SFs (3, 4), (3, 5), (3, 6) and (3, 7), respectively. A possible formation mechanism of these SFs is suggested, which involves a combination of Frank faults with Shockley ones. This provides a basic understanding of stacking faults in 6H-SiC and gives a rapid and non-destructive approach to identify SFs by low temperature photoluminescence.

  • 121.
    Sun, Jianwu
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Robert, T.
    Université Montpellier 2, France.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Juillaguet, S.
    Université Montpellier 2, France.
    Yakimova, Rositza
    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.
    Camassel, J.
    CNRS, Laboratoire Charles Coulomb, Montpellier, France.
    Low Temperature Photoluminescence Signature of Stacking Faults in 6H-SiC Epilayers Grown on Low Angle Off-axis Substrates2012Conference paper (Refereed)
    Abstract [en]

    The radiative recombination spectra of 6H-SiC epilayers grown on low angle (1.4° off-axis) substrates have been investigated by low temperature photoluminescence spectroscopy. Four different types of stacking faults have been identified, together with the presence of 3C-SiC inclusions. From the energy of the momentum-conserving phonons, four excitonic band gap energies have been found with Egx equal to 2.837, 2.698, 2.600 and 2.525 eV. These photoluminescence features, which give a rapid and non-destructive approach to identify stacking faults in 6H-SiC, provide a direct feedback to improve the material growth.

  • 122.
    Sun, Jianwu W.
    et al.
    Université Montpellier 2 and CNRS, France.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Mexis, M.
    Université Montpellier 2 and CNRS, France .
    Eriksson, Martin
    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.
    Tsiaoussis, I.
    Aristotle University of Thessaloniki, Greece.
    Yazdi, Gholamreza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Peyre, H.
    Université Montpellier 2 and CNRS, France.
    Juillaguet, S.
    Université Montpellier 2 and CNRS, France.
    Camassel, J.
    Université Montpellier 2 and CNRS, France.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Bergman, Peder
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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, Semiconductor Materials. Linköping University, The Institute of Technology.
    Comparative micro-photoluminescence investigation of ZnO hexagonal nanopillars and the seeding layer grown on 4H-SiC2012In: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 132, no 1, p. 122-127Article in journal (Refereed)
    Abstract [en]

    We report on a comparative micro-photoluminescence investigation of ZnO hexagonal nanopillars (HNPs) and the seeding layer grown on the off-axis 4H-SiC substrate. Transmission electron microscope (TEM) results establish that a thin seeding layer continuously covers the terraces of 4H-SiC prior to the growth of ZnO HNPs. Low temperature photoluminescence (LTPL) shows that ZnO HNPs are only dominated by strong donor bound exciton emissions without any deep level emissions. Micro-LTPL mapping demonstrates that this is specific also for the seeding layer. To further understand the recombination mechanisms, time-resolved micro-PL spectra (micro-TRPL) have been collected at 5 K and identical bi-exponential decays have been found on both the HNPs and seeding layer. Temperature-dependent TRPL indicates that the decay time of donor bound exciton is mainly determined by the contributions of non-radiative recombinations. This could be explained by the TEM observation of the non-radiative defects in both the seeding layer and HNPs, like domain boundaries and dislocations, generated at the ZnO/SiC interface due to biaxial strain.

  • 123. Sveinbjornsson, EO
    et al.
    Olafsson, HO
    Gudjonsson, G
    Allerstam, F
    Nilsson, Patrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Syväjärvi, Mikael
    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.
    Hallin, Christer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Rodle, T
    Jos, R
    High Field Effect Mobility in Si Face 4H-SiC MOSFET Made on Sublimation Grown Epitaxial Material2005In: Materials Science Forum, Vols. 483-485, 2005, Vol. 483, p. 841-844Conference paper (Refereed)
    Abstract [en]

    We report on fabrication and characterization of n-channel Si face 4H-SiC MOSFETs made using sublimation grown epitaxial material. Transistors made on this material exhibit record-high peak field effect mobility of 208 cm(2)/Vs while reference transistors made on a commercial epitaxial material grown by chemical vapor deposition (CVD) show field effect mobility of 125 cm(2)/VS. The mobility enhancement is attributed to better surface morphology of the sublimation grown epitaxial layer.

  • 124.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Letter: Perspectives of fluorescent and cubic silicon carbide2012In: Advanced Materials Letters, ISSN 0976-3961, E-ISSN 0976-397X, Vol. 3, no 3, p. 175-176Article in journal (Other academic)
    Abstract [en]

    [No abstract available]

  • 125.
    Syväjärvi, Mikael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Ciechonski, Rafal R.
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Yazdi, Gholamreza R.
    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.
    Fast epitaxy by PVT of SiC in hydrogen atmosphere2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 275, no 1-2, p. e1103-e1107 Article in journal (Refereed)
    Abstract [en]

    Epitaxial growth in hydrogen atmosphere has been studied in relation to sublimation epitaxial growth. A new type of features with a hexagonal shape are observed in the layers grown in hydrogen atmosphere. The morphological details of the features have been studied with optical microscopy and atomic force microscopy. An interactive relation of the defect appearance with the step flow growth mode seems to be present. The results are compared with growth in vacuum, argon, and helium conditions. The possible influence of thermal component to a reactive one in hydrogen etching is discussed.

  • 126.
    Syväjärvi, Mikael
    et al.
    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.
    Yazdi, Gholamreza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Forsberg, Urban
    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.
    A surface study of wet etched AlGaN epilayers grown by hot-wall MOCVD2007In: Journal of Crystal Growth, Vol. 300, 2007, Vol. 300, no 1, p. 242-245Conference paper (Refereed)
    Abstract [en]

    Epitaxial layers of AlGaN were grown by hot-wall MOCVD and their surfaces wet chemically etched with phosphorous acid. The as-grown surfaces and the development of the etched surfaces after 10 and 20 min of etching were studied with atomic force microscopy (AFM) and CL. In the as-grown layers growth features may be resolved while the RMS is as low as 1.4 Å in a scan area of 2×2 μm. Surfaces etched for 10 min had developed etch pits and a low RMS roughness of 7 Å indicating a uniform quality of the layers. Micrometer scale hexagonal features were observed after 20 min of etching. In some cases a deep hexagonal etch pit is observed in the centre of the hexagonal feature with a 30° rotation to each other, suggesting that the origin is substrate-induced defects. © 2006 Elsevier B.V. All rights reserved.

  • 127.
    Syväjärvi, Mikael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Ma, Quanbao
    University of Oslo, Norway.
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Galeckas, Augustinas
    University of Oslo, Norway.
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Liu, Xinyu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Jansson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Wellmann, Peter
    University of Erlangen Nurnberg, Germany.
    Linnarsson, Margareta
    KTH Royal Institute Technology, Sweden.
    Runde, Paal
    St Gobain Ceram Mat AS, Norway.
    Andre Johansen, Bertil
    St Gobain Ceram Mat AS, Norway.
    Thogersen, Annett
    SINTEF Mat and Chemistry, Norway.
    Diplas, Spyros
    SINTEF Mat and Chemistry, Norway.
    Almeida Carvalho, Patricia
    SINTEF Mat and Chemistry, Norway.
    Martin Lovvik, Ole
    SINTEF Mat and Chemistry, Norway.
    Nilsen Wright, Daniel
    SINTEF ICT, Norway.
    Yu Azarov, Alexander
    University of Oslo, Norway.
    Svensson, Bengt G.
    University of Oslo, Norway.
    Cubic silicon carbide as a potential photovoltaic material2016In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 145, p. 104-108Article in journal (Refereed)
    Abstract [en]

    In this work we present a significant advancement in cubic silicon carbide (3C-SiC) growth in terms of crystal quality and domain size, and indicate its potential use in photovoltaics. To date, the use of 3C-SiC for photovoltaics has not been considered due to the band gap of 2.3 eV being too large for conventional solar cells. Doping of 3C-SiC with boron introduces an energy level of 0.7 eV above the valence band. Such energy level may form an intermediate band (IB) in the band gap. This IB concept has been presented in the literature to act as an energy ladder that allows absorption of sub-bandgap photons to generate extra electron-hole pairs and increase the efficiency of a solar cell. The main challenge with this concept is to find a materials system that could realize such efficient photovoltaic behavior. The 3C-SiC bandgap and boron energy level fits nicely into the concept, but has not been explored for an IB behavior. For a long time crystalline 3C-SiC has been challenging to grow due to its metastable nature. The material mainly consists of a large number of small domains if the 3C polytype is maintained. In our work a crystal growth process was realized by a new approach that is a combination of initial nucleation and step-flow growth. In the process, the domains that form initially extend laterally to make larger 3C-SiC domains, thus leading to a pronounced improvement in crystalline quality of 3C-SiC. In order to explore the feasibility of IB in 3C-SiC using boron, we have explored two routes of introducing boron impurities; ion implantation on un-doped samples and epitaxial growth on un-doped samples using pre-doped source material. The results show that 3C-SiC doped with boron is an optically active material, and thus is interesting to be further studied for IB behavior. For the ion implanted samples the crystal quality was maintained even after high implantation doses and subsequent annealing. The same was true for the samples grown with pre-doped source material, even with a high concentration of boron impurities. We present optical emission and absorption properties of as-grown and boron implanted 3C-SiC. The low-temperature photoluminescence spectra indicate the formation of optically active deep boron centers, which may be utilized for achieving an IB behavior at sufficiently high dopant concentrations. We also discuss the potential of boron doped 3C-SiC base material in a broader range of applications, such as in photovoltaics, biomarkers and hydrogen generation by splitting water. (C) 2015 Elsevier B.V. All rights reserved.

  • 128.
    Syväjärvi, Mikael
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Müller, J.
    University of Erlangen-Nürnberg, Erlangen, Germany .
    Sun, Jianwu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Grivickas, Vytautas
    Vilnius University, Lithuania.
    Ou, Yiyu
    Jokubavicius, Valdas
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hens, Philip
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kaisr, M.
    University of Erlangen-Nürnberg, Erlangen, Germany .
    Ariyawong, Kanaparin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Gulbinas, K.
    Vilnius University, Lithuania.
    Liljedahl, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Linnarsson, M. K.
    Royal Institute of Technology, Kista-Stockholm .
    Kamiyama, S.
    Meijo University, Nagoya, Japan .
    Wellmann, P.
    University of Erlangen-Nürnberg, Erlangen, Germany .
    Spiecker, E.
    University of Erlangen-Nürnberg, Erlangen, Germany .
    Ou, H.
    Technical University of Denmark, Lyngby.
    Fluorescent SiC as a new material for white LEDs2012In: Physica scripta. T, ISSN 0281-1847, Vol. T148, p. 014002-Article in journal (Refereed)
    Abstract [en]

    Current III–V-based white light-emitting diodes (LEDs) are available. However, their yellow phosphor converter is not efficient at high currents and includes rare-earth metals, which are becoming scarce. In this paper, we present the growth of a fluorescent silicon carbide material that is obtained by nitrogen and boron doping and that acts as a converter using a semiconductor. The luminescence is obtained at room temperature, and shows a broad luminescence band characteristic of donor-to-acceptor pair recombination. Photoluminescence intensities and carrier lifetimes reflect a sensitivity to nitrogen and boron concentrations. For an LED device, the growth needs to apply low-off-axis substrates. We show by ultra-high-resolution analytical transmission electron microscopy using aberration-corrected electrons that the growth mechanism can be stable and that there is a perfect epitaxial relation from the low-off-axis substrate and the doped layer even when there is step-bunching.

  • 129.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Nasi, L.
    Yazdi, Gholamreza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Salviati, G.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Chen, Weimin
    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.
    Formation of ferromagnetic SiC: Mn phases2005In: Materials Science Forum, Vols. 483-485, 2005, Vol. 483-485, p. 241-244Conference paper (Refereed)
    Abstract [en]

    Ferromagnetic phases in as-grown SiC have been studied. An interpretation about the formation based on details of the phase appearance in the layers from optical microscopy, AFM, and TEM investigations is related to the growth. Some phases were found to have a nucleation at the edge of the phase and detailed TEM investigations show that the phases have an increased grain density at the edge while the main part of the phase is monocrystalline.

  • 130.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Sritirawisarn, N.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Initial Growth in 3C-SiC Sublimation Epitaxy on 6H-SiC2007In: ECSCRM 2006,2006, Material Science Forum, vol. 556-557: Trans Tech Publications , 2007, p. 195-Conference paper (Refereed)
  • 131.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Stanciu, V.
    Izadifard, Morteza
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Buyanova, Irina
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Svedlindh, P.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    As-grown 4H-SiC epilayers with magnetic properties2004In: SILICON CARBIDE AND RELATED MATERIALS 2003, PRTS 1 AND 2, 2004, p. 747-750Conference paper (Refereed)
    Abstract [en]

    A growth process for diluted magnetic SiC has been explored for as-grown epitaxiallayers by introducing Mn ions. Depending on the growth conditions, either high Mn doping orexcess concentrations with second phases may form in the layers. Under those conditions wherecompound phases appear, there is a magnetic response in the material as demonstrated usingSQUID measurements with a transition temperature of 160K in the as-grown material. There is noresponse in layers for which the second phases have been removed by etching.

  • 132.
    Syväjärvi, Mikael
    et al.
    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 .
    Silicon carbide epitaxial layer and method of producing the same2007Patent (Other (popular science, discussion, etc.))
  • 133.
    Syväjärvi, Mikael
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Yakimova, RositsaLinköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Wide band gap materials and new developments2006Collection (editor) (Other academic)
  • 134.
    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.
    Arjunan, A.
    Toupitsyn, E.
    Sudarshan, T.S.
    Stability of thick layers grown on (1-100) and (11-20) orientations of 4H-SiC2006In: Materials Science Forum, Vols. 527-529, 2006, Vol. 527-529, p. 227-230Conference paper (Refereed)
  • 135.
    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.
    Ciechonski, Rafal
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Davydov, D
    Lebedev, Alexander
    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.
    Origin and behaviour of deep levels in sublimation growth of 4H-SiC layers2003In: Materials Science Forum, Vols. 433-436, 2003, Vol. 433-4, p. 169-172Conference paper (Refereed)
    Abstract [en]

    The characteristics of boron incorporation and the resultant electrical behaviour have been studied for sublimation grown epilayers. Some factors which influence are the purity of the source material, growth temperature and growth time. The electrical activity of the shallow and deep level of boron has been investigated in relation to growth parameters and from the results the nature of the deep boron complex is discussed. The use of TaC coated graphite crucibles resulted in a decrease of the Z(1,2) concentration to less than low E13 cm(-3) which is the concentration obtained using graphite crucibles.

  • 136.
    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.
    Ciechonski, Rafal
    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.
    Comparison of SiC sublimation epitaxial growth in graphite and TaC coated crucibles2003In: Diam. relat. Mater. Vol.12, 2003, Vol. 12, no 10-11, p. 1936-1939Conference paper (Refereed)
    Abstract [en]

    The growth behaviour in graphite crucibles of different constructions and crucibles coated with TaC are studied with respect to growth performances such as growth rate, epilayer thickness variation and doping as well as deep levels. The variation of growth rate and the epilayer surface morphology with crucible position relative to the coil used for induction heating to applied growth temperature is studied. At low growth rate defects extended along the steps are observed. © 2003 Elsevier B.V. All rights reserved.

  • 137.
    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.
    Ciechonski, Rafal
    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.
    Storasta, Liutauras
    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.
    Deep levels in 4H-SiC layers grown by sublimation epitaxy2003In: Optical Materials, Vol. 23, 2003, Vol. 23, no 1-2, p. 61-64Conference paper (Refereed)
    Abstract [en]

    Deep levels arising from incorporation of boron in epitaxial layers are presented together with studies of the Z1,2 deep level. The resultant concentrations are related to growth conditions such as growth time and growth temperature. From this the nature and incorporation of the unresolved deeper boron level is commented. The electrical activity of deep boron centers are compared with the actual amount of boron in the material and concerning their relative concentration differences. © 2003 Elsevier Science B.V. All rights reserved.

  • 138.
    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.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Linnarsson, M
    Royal Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Optical properties of aluminium and nitrogen in compensated 4H-SiC epitaxial layers2001In: Materials Research Society Symposium Proceedings, Vol. 640, 2001, p. H7.10.1-H7.10.6Conference paper (Refereed)
  • 139.
    Syväjärvi, Mikael
    et al.
    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 .
    Hylen, AL
    Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden Okmet AB, S-17824 Ekero, Sweden.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Anisotropy of dissolution and defect revealing on SiC surfaces1999In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 11, no 49, p. 10041-10046Article in journal (Refereed)
    Abstract [en]

    Micropipes and dislocations in silicon carbide single crystals are revealed by chemical etching. Micropipes are shown to be interconnected with other structural defects and the reason for this is discussed. The Si and C faces are attacked by molten KOH preferentially and isotropically, respectively. The mechanism is discussed in relation to the different surface free energies on the Si and C faces. The revealing of micropipes is more pronounced on the Si face. The hexagonal pattern of micropipes are revealed by rapid etching provided by a large undersaturation at the surface. It is shown that etching from a melt gives a disintegration of the SiC crystal at the micropipe via spiral dissolution which is due to etching near equilibrium conditions. The temperature dependence of the etch rate follows an Arrhenius dependence with an apparent activation energy of about 12-15 kcal mol(-1) derived from measuring etch rate and weight loss.

  • 140.
    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.
    Iakimov, Tihomir
    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.
    Characterization of anisotropic step-bunching on as-grown SiC surfaces2000In: Materials Science Forum, Vols. 338-343, Trans Tech Publications Inc., 2000, Vol. 338-3, p. 375-378Conference paper (Refereed)
    Abstract [en]

    We report the presence of anisotropic step-bunching in SiC epitaxy on off-oriented substrates. This is an effect of step-flow growth. The anisotropic step-bunching is discussed in relation to the temperature dependence of lateral growth velocities and the interface roughness. The macrostep appearance is probably related to formation of morphologically stable faces with low surface free energy.

  • 141.
    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.
    Iwaya, M.
    Meijo University, Nagoya, Japan.
    Takeuchi, T.
    Meijo University, Nagoya, Japan.
    Akasaki, I.
    Meijo University, Nagoya, Japan.
    Kamiyama, Satoshi
    Meijo University, Nagoya, Japan.
    Growth and light properties of fluorescent SiC for white LEDs2012In: Materials Science Forum Vols 717 - 720, Trans Tech Publications Inc., 2012, Vol. 717-720, p. 87-92Conference paper (Refereed)
    Abstract [en]

    The LED technology started to developed many years ago with red light emitting diodes. To achieve the blue LED, novel growth technologies and process steps were explored, and made it possible to demonstrate efficient blue LED performance from nitrides. The efficiency was further developed and blue LEDs were commercially introduced in the 1990s. The white LED became possible by the use of the blue LED and a phosphor that converts a part of the blue light to other colors in the visible range to combine into white light. However, even today there are limitations in the phosphor-based white LED technology, in particular for general lighting, and new solutions should be explored to speed the pace when white LEDs will be able to make substantial energy savings. In this paper we overview gallium nitride materials evolution and growth concepts for LEDs. We describe the fluorescent silicon carbide material prepared by a novel growth technology for a new type of white LED in general lighting with pure white light. This paper introduces an interesting research in fundamental growth and optical properties of light emitting silicon carbide.

  • 142.
    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.
    Jacobsson, Henrik
    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.
    Growth of 3C-SiC using off-oriented 6H-SiC substrates2001In: Materials Science Forum, Vols. 353-356, 2001, Vol. 353-3, p. 143-146Conference paper (Refereed)
    Abstract [en]

    Large area growth of 3C-SiC on off-oriented 6H-SiC substrates is demonstrated and the growth evolution is investigated. The structural quality assessed from high-resolution x-ray diffraction omega -rocking curve measurements shows a symmetric peak with a full width at half maximum of 36 arcsec and 2 theta/theta measurements show that the lattice in the grown 3C-SiC is not distorted by using 6H-SiC as a substrate.

  • 143.
    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.
    Jacobsson, Henrik
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    High growth rate epitaxy of 4H-SiC layers with improved crystal quality2000In: Proc. III Intern. Seminar on SiC and Related Materials, 2000, p. 83-88Conference paper (Refereed)
  • 144.
    Syväjärvi, Mikael
    et al.
    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 .
    Jacobsson, Henrik
    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, Materials Science .
    Structural improvement in sublimation epitaxy of 4H-SiC2000In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 88, no 3, p. 1407-1411Article in journal (Refereed)
    Abstract [en]

    The sublimation epitaxy growth process has been studied. The structural quality of the grown layers improves compared with the substrate mainly due to a diminished domain structure misorientation. Optical microscopy shows that the as-grown surfaces are free of typical defects appearing in silicon carbice (SiC) epitaxy, whereas atomic force microcopy measurements show macrosteps. As a possible technique to produce high-quality 4H-SiC, sublimation epitaxy was performed on substrates containing a layer grown by liquid phase epitaxy which is a growth process for closing micropipes in the initial substrate. In spite of the initial surface roughness of the liquid phase epitaxy layer, the surface morphology of the sublimation grown epilayers remained smooth and the structural quality improvement was maintained. This does not occur if the initial surfaces are too rough. A suggestion for roughness reduction is presented. The growth conditions (growth rate ramp up, growth temperature, temperature gradient, source to substrate distance, and substrate surface orientation) leading to the results are presented. A model for the mechanism for structural improvement is outlined and supporting experimental observations are given. (C) 2000 American Institute of Physics. [S0021-8979(00)07915-9].

  • 145.
    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.
    Jacobsson, Henrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Linnarsson, MK
    Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Okmet AB, SE-17824 Ekero, Sweden Royal Inst Technol, Dept Solid State Elect, SE-16440 Stockholm, Sweden.
    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.
    High growth rate epitaxy of thick 4H-SiC layers2000In: Materials Science Forum, Vols. 338-342, Scientific.Net , 2000, Vol. 338-3, p. 165-168Conference paper (Refereed)
    Abstract [en]

    Sublimation epitaxy for fabrication of thick 4H-SiC layers has been studied with respect to surface morphology, structural quality, and purity. The surface morphology of thick (50-100 mum) epilayers is smooth, even though the growth rate was 100 mum/h. These surfaces are obtained within a parameter window for morphological stability. The structural perfection is confirmed by high-resolution X-Ray diffraction measurements and the epilayer quality is improved compared with the substrate. The limitation in purity is dependent mainly on the purity of the SiC source material. The growth system purity, mainly graphite and Ta parts of the growth crucible, is also of major importance. Results from intentional doping for high-resistive, semi-insulating and p-type material are presented.

  • 146.
    Syväjärvi, Mikael
    et al.
    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 .
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Anisotropic etching of SiC2000In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 147, no 9, p. 3519-3522Article in journal (Refereed)
    Abstract [en]

    The etching effect using molten KOH of micropipes and dislocations in silicon carbide single crystals is investigated. Most of the etch pits become hexagonal due to an anisotropic etching behavior. Micropipes are interconnected with dislocations, and this observation is discussed in relation to the growth process. The hexagonal pattern of micropipes is revealed by rapid etching provided by a large undersaturation. Etching from a melt gives a disintegration of the SiC crystal at the micropipe via spiral dissolution as a consequence of etching near equilibrium conditions. The Si- and C-faces are attacked by molten KOH preferentially and isotropically, respectively. The size of the micropipes with increasing etching time is studied for both the Si- and C-faces. The temperature dependence of the etch rate follows an Arrhenius dependence with an apparent activation energy of about 12-15 kcal/mol derived from measuring the etch rate and weight loss.

  • 147.
    Syväjärvi, Mikael
    et al.
    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 .
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Cross-sectional cleavages of SiC for evaluation of epitaxial layers2000In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 208, no 1, p. 409-415Article in journal (Refereed)
    Abstract [en]

    The application of cleavages on SiC epitaxial layers are presented as a feedback for an evaluation of the growth. The preferred cleavage planes are described and discussed in relation to the atomic configuration of the SiC lattice. From the cleavages it is possible to relate defect behaviour to the growth mechanism and obtain information which can not be revealed by studying as-grown epilayer surfaces. For demonstration, a variety of defects revealed by cleavages are investigated for SiC epitaxial layers.

  • 148.
    Syväjärvi, Mikael
    et al.
    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 .
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Step-bunching in 6H-SiC growth by sublimation epitaxy1999In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 11, no 49, p. 10019-10024Article in journal (Refereed)
    Abstract [en]

    Thick 6H-SiC epitaxial layers grown by sublimation epitaxy have been investigated concerning step-bunching. The macrostep appearances on the surfaces were studied for both (0001) Si and (000 (1) over bar) C faces. The surface structure on the Si face is less regular compared with the C face. Data on the steps have been collected and the step height shows a linear relation with the step width.

  • 149.
    Syväjärvi, Mikael
    et al.
    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 .
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Step-bunching in SiC epitaxy: Anisotropy and influence of growth temperature2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 236, no 1-3, p. 297-304Article in journal (Refereed)
    Abstract [en]

    The anisotropy of step-bunching in silicon carbide (SiC) epitaxy on off-oriented substrates is an effect which occurs in step-flow growth. The formation mechanism is discussed in relation to the temperature dependence of lateral growth velocities and the interface roughness. The macrostep appearance is probably related to the formation of stable faces with low surface free energy. As-grown surfaces of sublimation grown layers have been studied in detail using atomic force microscopy. Data of macrosteps have been collected in relation to the widths of the macrosteps and their heights at different growth temperatures. The relative difference between the surface free energies of the terrace and the facet of the step is estimated for 6H-SiC as well as for 4H-SiC grown on the Si- and C-face in the temperature range from 1750°C to 1800°C. © 2002 Elsevier Science B.V. All rights reserved.

  • 150.
    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.
    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.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kinetics and morphological stability in sublimation growth of 6H and 4H-SiC epitaxial layers1999In: Materials Science and Engineering: B, ISSN 0921-5107, Vol. 61-62, p. 161-164Article in journal (Refereed)
    Abstract [en]

    Very high growth rates (>2 mm h−1) in SiC epitaxy have been achieved. The rate determining mechanism changes from diffusion to kinetics when the growth pressure decreases below 5–10 mbar. At low pressures it is shown that sublimation of the SiC source is the rate determining step and that there is a free molecular transport from source to substrate. The growth rate is constant during several hours of growth and Si losses from the crucible are very small. These facts show that our growth system is stable. The obtained apparent activation energy (130 kcal mol−1) is attributed to the sublimation rate of the SiC source material. The morphology is smooth and the surfaces are specular if the growth conditions are selected within the given parameter window for morphological stability. The origin of the growth disturbances is discussed.

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