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  • 2051.
    Zhao, Qingxiang
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Liu, Xinyu
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Properties of shallow donors in ZnMgO epilayers grown by metal organic chemical vapor deposition2014In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, no 18, p. 183508-Article in journal (Refereed)
    Abstract [en]

    High quality Zn1-xMgxO epilayers have been grown by means of metal organic chemical vapor deposition technique on top of ZnO templates. The grown samples were investigated by x-ray photoelectron spectroscopy and photoluminescence. The magnesium (Mg) concentration was varied between 0% and 3% in order to study the properties of shallow donors. The free and donor bound excitons could be observed simultaneously in our high quality Zn1-xMgxO epilayers in the photoluminescence spectra. The results indicate that both built-in strain and Mg-concentration influence the donor exciton binding energy. It clearly shows that the donor exciton binding energy decreases with increasing Mg-concentration and with increasing built-in strain. Furthermore, the results indicate that the donor bound exciton transition energy increases with decreasing strength of the built-in strain if the Mg-concentration is kept the same in the Zn1-xMgxO epilayers.

  • 2052.
    Zhao, Qingxiang
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Physics and Electronics.
    Yang, Li-Li
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Sernelius, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Willander, Magnus
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology, Physics and Electronics.
    Surface recombination in ZnO nanorods grown by chemical bath deposition2008In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 104, no 7, p. 073526-Article in journal (Refereed)
    Abstract [en]

    Verticallywell-aligned ZnO nanorods on Si substrates were prepared by atwo-step chemical bath deposition (CBD) method. The optical properties ofthe grown ZnO nanorods were investigated by time resolved photoluminescencespectroscopy. It was found that the effective decay time ofthe near bandgap recombination in the CBD grown ZnO nanorodsstrongly depends on the diameter of the ZnO nanorods. Typically,the decay curves obtained from these ZnO nanorods show acombination of two exponential decays. The experimental results show thatthe fast exponential decay is related to the surface recombinationand the slow decay is related to the “bulk” decay.The measured decay time of the effective surface recombination decreaseswith decreasing diameter, while the bulk decay time remains unchanged.The results also show that an annealing treatment around 500 °Csignificantly reduces the surface recombination rate. A simple carrier andexciton diffusion equation is also used to determine the surfacerecombination velocity, which results in a value between 1.5 and4.5 nm/ps.

  • 2053.
    Zhao, Qingxiang
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Yang, Li-Li
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Surface Recombination in ZnO Nanorods Grown by Aqueous Chemical Method2009In: PHYSICS OF SEMICONDUCTORS: 29th International Conference on the Physics of Semiconductors / [ed] Marília J. Caldas, Nelson Studart, Melville, N.Y, USA: American Institute of Physics (AIP), 2009, p. 319-320Conference paper (Refereed)
    Abstract [en]

    ZnO nanorods on Si substrates were prepared by either a two-steps chemical bath deposition (CBD) method or thermal evaporation technique. 11 was found that the effective decay time of the near bandgap recombinations strongly depends on the method, which was used to grow the ZnO nanorods. ZnO nanorods grown by the CBD exhibit characteriristic two-exponential decay curves, while ZnO nanorods grown by thermal evaporation technique show single exponential decays. The experimental results show that the fast exponential decay from the CBD grown ZnO nanorods is related to the surface recombination, while the slow decay is related to the "bulk" decay. The results also show that an annealing treatment around 500 degrees C to 700 degrees C significantly reduces the surface recombination rate.

  • 2054.
    Zhao, Q.X.
    et al.
    Physical Electronics and Photonics, Department of Physics, Chalmers University of Technology and University of Göteborg, Sweden.
    Willander, M.
    Physical Electronics and Photonics, Department of Physics, Chalmers University of Technology and University of Göteborg, Sweden.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Lu, W.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai China.
    Shen, S.C.
    National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai China.
    Dynamic properties of radiative recombination in p-type d-doped layers in GaAs2001In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 63, article id 125337Article in journal (Refereed)
    Abstract [en]

     We present an optical study of thin Zn-doped GaAs layers embedded in bulk GaAs, grown by metal-organic vapor-phase-epitaxy by means of stationary and time-resolved optical spectroscopy. The concentration of the Zn acceptors was aimed at 2×1020/cm3 in 4-nm-wide doping regions. The intensity of the optical radiative transition (so called the F emission) appearing in photoluminescence spectra was found to be related to holes confined at doping regions. The F emission shows a strong dependence on excitation intensity and temperature. The energy position varies from 1.46 to 1.49 eV as the excitation density changes from about 40 mW/cm2 to 23 W/cm2. The dynamic properties of the F-emission band have been studied by time-resolved spectroscopy. The F emission shows a nonexponential decay character. The decay time of the F emission exhibits a strong dependence on the detection energy within the F-emission band. The decay time becomes longer as the detection energy is redshifted.

  • 2055. Zhao, Q.X.
    et al.
    Wongmanerod, S.
    Willander, M.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Wang, S.M.
    Sadeghi, M.
    Electronic structure of beryllium acceptors confined in GaAs/AlxGa1-xAs quantum wells2001Article in journal (Refereed)
    Abstract [en]

    A detailed experimental investigation is presented of beryllium acceptors confined in GaAs/AlxGa1-xAs quantum well structures in the presence of an applied magnetic field. A number of features related to the transitions between the acceptor ground and excited states are reported: (1) the satellites corresponding to the 1S-2S acceptor transition involving the different components [j = 3/2(G8) and j = 5/2(G7,8)] of the acceptor bound exciton (BE), where the labels of the exciton states are according to j-j coupling theory (or the cubic crystal-field scheme), (2) the detailed splitting of the 1S3/2(G6)-2S3/2(G6) acceptor transition involving the lowest acceptor BE state j = 5/2(G7,8), and (3) a component of the 1S-2P acceptor transition. In addition to this, the magnetic field dependence of these transitions is investigated experimentally, and the results are compared with theoretical predictions based on existing theory.

  • 2056.
    Zhao, QX
    et al.
    Physical Electronics and Photonics, Department of Microelectronics and Nanoscience, Chalmers University of Technology and Göteborg University, Göteborg, Sweden.
    Wongmanerod, S
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Willander, Magnus
    Physical Electronics and Photonics, Department of Microelectronics and Nanoscience, Chalmers University of Technology and Göteborg University, Göteborg, Sweden.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Selvig, E
    Department of Physical Electronics, Norwegian University of Science and Technology, Trondheim, Norway.
    Fimland, BO
    Department of Physical Electronics, Norwegian University of Science and Technology, Trondheim, Norway.
    Effects of monolayer AlAs insertion in modulation doped GaAs/AlxGa1-xAs quantum-well structures2000In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 62, no 16, p. 10984-10989Article in journal (Refereed)
    Abstract [en]

    Symmetrically modulation doped GaAs/AlxGa1-xAs quantum-well structures, containing a monolayer thickness of single AlAs insertion in the well region, are studied by photoluminescence spectroscopy and electrical characterization. The aim of this study is to explore how the AlAs insertion influences the electronic properties of the structures and the mobility of the carrier confined in the well layer. We find that the electronic structure of the confined electrons is strongly influenced by the AlAs insertion in the modulation doped structures. The effective mass of the particles involved in the observed optical transition and the transition energy were deduced from magneto-optical measurements, while the mobility and carrier concentration were, obtained from the Hall measurements. The experimentally deduced transition energies are compared with the results from a simple self-consistent calculation.

  • 2057.
    Zhou, Mi
    et al.
    University of N Texas.
    Pasquale, Frank L
    University of N Texas.
    Dowben, Peter A
    University of Nebraska Lincoln.
    Boosalis, Alex
    University of Nebraska Lincoln.
    Schubert, Mathias
    University of Nebraska Lincoln.
    Darakchieva, Vanya
    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.
    Kong, Lingmei
    University of Nebraska Lincoln.
    Kelber, Jeffry A
    University of N Texas.
    Direct graphene growth on Co3O4(111) by molecular beam epitaxy2012In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 24, no 7, p. 072201-Article in journal (Refereed)
    Abstract [en]

    Direct growth of graphene on Co3O4(111) at 1000 K was achieved by molecular beam epitaxy from a graphite source. Auger spectroscopy shows a characteristic sp(2) carbon lineshape, at average carbon coverages from 0.4 to 3 ML. Low energy electron diffraction (LEED) indicates (111) ordering of the sp2 carbon film with a lattice constant of 2.5(+/-0.1) angstrom characteristic of graphene. Sixfold symmetry of the graphene diffraction spots is observed at 0.4, 1 and 3 ML. The LEED data also indicate an average domain size of similar to 1800 angstrom, and show an incommensurate interface with the Co3O4(111) substrate, where the latter exhibits a lattice constant of 2.8(+/-0.1) angstrom. Core level photoemission shows a characteristically asymmetric C(1s) feature, with the expected pi to pi* satellite feature, but with a binding energy for the 3 ML film of 284.9(+/-0.1) eV, indicative of substantial graphene-to-oxide charge transfer. Spectroscopic ellipsometry data demonstrate broad similarity with graphene samples physically transferred to SiO2 or grown on SiC substrates, but with the pi to pi* absorption blue-shifted, consistent with charge transfer to the substrate. The ability to grow graphene directly on magnetically and electrically polarizable substrates opens new opportunities for industrial scale development of charge- and spin-based devices.

  • 2058.
    Zhou, Shuai
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Beijing University of Posts and Telecommun, Peoples R China; China International Telecommunication Construction Group Design Institute Co., Ltd, Beijing, Peoples R China.
    Liu, Yumin
    Beijing University of Posts and Telecommun, Peoples R China.
    Wang, Donglin
    Beijing University of Posts and Telecommun, Peoples R China.
    Yu, Zhongyuan
    Beijing University of Posts and Telecommun, Peoples R China.
    Zhao, Wei
    China Int Telecommun Construct Grp Design Institute Co, Peoples R China.
    Le, Lifeng
    China Int Telecommun Construct Grp Design Institute Co, Peoples R China.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    The calculation of InGaN quantum dot formation mechanism on GaN pyramid2015In: Superlattices and Microstructures, ISSN 0749-6036, E-ISSN 1096-3677, Vol. 84, p. 72-79Article in journal (Refereed)
    Abstract [en]

    An equilibrium approach is used to calculate the free energy and composition distribution of InGaN/GaN quantum dot located on the InGaN/GaN pyramid. The energy balance method is adopted to predict critical conditions for quantum dot formation. We find that the formation of QD depends strongly on the size of pyramid top surface. The results can fit our experiment qualitatively.

  • 2059. Zhu, Q.
    et al.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Byszewski, M.
    Rudra, A.
    Pelucchi, E.
    He, Z.
    Kapon, E.
    Hybridization of electron and hole states in pyramidal quantum dot molecules2008In: The 5th International Conerence on Semiconductor Quantum Dots QD2008,2008, 2008Conference paper (Other academic)
  • 2060. Zhu, Q.
    et al.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Rudra, A.
    Pelucchi, E.
    Byszewski, M.
    Gallo, P.
    Kapon, E.
    Control of Light Polarization using Semiconductor Quantum Dot Molecules2007In: OSA topical Conference in Nanophotonics,2007, 2007Conference paper (Other academic)
  • 2061. Zhu, Q.
    et al.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Rudra, A.
    Pelucchi, E.
    Byszewski, M.
    Gallo, P.
    Kapon, E.
    Quantum Dot Molecules and Superlattices Realized with Modulated Quantum Wire Heterostructures2007In: 13th International Conference Modulated Semiconductor Structures MSS 13,2007, 2007Conference paper (Other academic)
  • 2062. Zhu, Q.
    et al.
    Pelucchi, E.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Dalessi, S.
    Dupertuis, M.-A.
    Kapon, E.
    Experimental Observation of Transition from 2D to 3D Quantum Confinement in Semiconductor Quantum Wires/Quantum dots2006In: SCOPES Seminar,2006, 2006Conference paper (Other academic)
  • 2063. Zhu, Q.
    et al.
    Pelucchi, E.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Dalessi, S.
    Dupertuis, M.-A.
    Moret, N.
    Oberli, D.Y.
    Kapon, E.
    Semiconductor Quantum Wires with Controlled Length and Confinement Potential2006In: 28th International Conference on the Physics of Semiconductors ICPS,2006, 2006Conference paper (Other academic)
  • 2064. Zhu, Q.
    et al.
    Pelucchi, E.
    Karlsson, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Moret, N.
    Oberli, D.
    Kapon, E.
    Continuous transition from 2D to 3D quantum confinement realized with pyramidal quantum wires and dots2006In: 4th International Conference on Quantum Dots,2006, 2006Conference paper (Other academic)
  • 2065.
    Zhu, Qing
    et al.
    Ecole Polytech, Lausanne.
    Karlsson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Byszewski, Marcin
    Ecole Polytech, Lausanne.
    Rudra, Alok
    Ecole Polytech, Lausanne.
    Pelucchi, Emanuele
    Ecole Polytech, Lausanne.
    He, Zhanbing
    Ecole Polytech, Lausanne.
    Kapon, Eli
    Ecole Polytech, Lausanne.
    Hybridization of Electron and Hole States in Semiconductor Quantum-Dot Molecules2009In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 5, no 3, p. 329-335Article in journal (Refereed)
    Abstract [en]

    A novel QD-molecule system is realized using metal–organic vapor-phase epitaxy growth. The dots are tunnel coupled via connected quantum wires (QWRs). The stronger tunnel coupling in this integrated QD-QWR system allows the hybridization of both electron and hole states, yielding direct-real-space excitonic molecules (see image). The structure holds promise for nanophotonic devices for quantum-information-processing applications.

  • 2066.
    Zhu, Xiaolong
    et al.
    Technical University of Denmark, Lyngby.
    Ou, Yiyu
    Technical University of Denmark, Lyngby.
    Jokubavicius, 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.
    Hansen, Ole
    Technical University of Denmark, Lyngby.
    Ou, Haiyan
    Technical University of Denmark, Lyngby.
    Mortensen, N. Asger
    Technical University of Denmark, Lyngby.
    Xiao, Sanshui
    Technical University of Denmark, Lyngby.
    Broadband light-extraction enhanced by arrays of whispering gallery resonators2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 24Article in journal (Refereed)
    Abstract [en]

    We demonstrate a light-extraction approach using a whispering gallery resonators array. The wavelength-scale resonant dielectric nanospheres support whispering gallery modes, which can be coupled with the confined waveguide modes inside the bulk material, thus dramatically improving light extraction. Broadband light-extraction enhancement across the entire visible spectral range is achieved by exciting three low-order and low-quality-factor resonances. As an example, the broadband extraction enhancement of about 50% is obtained for the emission of fluorescent SiC at all the tested angles. The experimental results are supported by numerical simulations. Our light-extraction strategy could enable the manufacturing of high-throughput, nondestructive, and affordable optical coating in a variety of optical devices.

  • 2067.
    Zhuravlev, K S
    et al.
    Physics Dept, Novosibirsk.
    Alexandrov, I A
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Linear polarized photoluminescence from GaN quantum dots imbedded in AlN matrix2010Conference paper (Refereed)
    Abstract [en]

    We report microphotoluminescence studies of GaN/AlN quantum dots grown along the (0001) crystal axis by molecular-beam epitaxy on sapphire substrates. To obtain quantum dots with different density and size a nominal GaN coverage was varied from 1 to 4 monolayers. The highest density of quantum dots was about 1011 cm-2, so about 103 quantum dots was excited in experiments. We found that the photoluminescence intensity of a sample with the smallest amount of deposited GaN decreases in more than two orders of magnitude under continuous-wave laser exposure during about 30 minutes and then it remains stable. The photoluminescence intensity of the rest samples was time-independent quantity. The emission band of the former sample exhibits a prominent linear polarization along the growth plane. We assume that the quite high degree of polarization can be due anisotropy of strain and/or shape of the quantum dots formed near dislocations which act also as recombination centers causing photoluminescence quenching.

  • 2068.
    Zhuravlev, K S
    et al.
    n/a.
    Alexandrov, I A
    n/a.
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Linearly polarized photoluminescence from GaN quantum dots embedded in AlN matrix2009In: International Conference on Physics, Chemistry and Applications of Nanostructures, Belarus, 2009Conference paper (Refereed)
  • 2069. Zhuravlev, K S
    et al.
    Mansurov, V G
    Yu, A
    Nikitin, A
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Mobile and immobile photoluminescence bands from single hexagonal GaN quantum dots embedded in an AlN matrix2008In: ICPS 29th International Conference on the Physics of Semiconductors,2008, 2008Conference paper (Refereed)
  • 2070. Zhuravlev, KS
    et al.
    Mansurov, VG
    YU, A
    Nikitin, A
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Power dependence of photoluminescence from single hexagonal GaN quantum dots formed in an AlN matrix2007In: NANO-2007 workshop,2007, 2007Conference paper (Refereed)
  • 2071. Zhuravlev, K.S.
    et al.
    Ree, D.D.
    Mansurov, V.G.
    Nikitin, A.Yu.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Microphotoluminescence of GaN/AlN quantum dots grown by MBE2006In: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 3, p. 2048-2051Article in journal (Refereed)
    Abstract [en]

    Presented at: The 6th International Conference on Nitride Semiconductors (ICNS6), Bremen, Germany, Aug 28-Sept 2, 2005

  • 2072. Zhuravlev, KS
    et al.
    Shamirzaev, TS
    Larsson, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Holtz, Per-Olof
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Photo-luminescence of single InAs quantum dots in an AlAs matrix2007In: NANO-2007 workshop,2007, 2007Conference paper (Refereed)
  • 2073. Ziane, D
    et al.
    Bluet, JM
    Guillot, G
    Godignon, P
    Monserrat, J
    Ciechonski, Rafal
    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.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Chen, L
    Mawby, P
    Characterizations of SiC/SiO2 interface quality toward high power MOSFETs realization2004In: Materials Science Forum, Vols. 457-460, 2004, Vol. 457-460, p. 1281-1286Conference paper (Refereed)
    Abstract [en]

    The low channel mobility in N-MOS 4H-SiC transistor is a major key issue for the development of power devices with satisfactory on state characteristics. Previous works have demonstrated that this low channel mobility is due to high interface state density (Dit) near the conduction band edge. Furthermore, the realization of SiC MOSFETs sustaining high reverse field necessitates thick epitaxial layer growth. An important thickness (> 30 gm) unfortunately involves important surface roughness which may result in a high interface trap density (Dit) and surface potential fluctuation (sigma(s)) at the SiC/SiO2 interface. In this study, we focus on SiO2/SiC MOS interface quality characterization as a function of process conditions and material properties (dopant type, thick layer growth technique). Investigations of the oxide quality on thick layers grown by CVD and PVT has been realized using CV under UV lightening and GV techniques. We evidenced that the Dit value (between 10(10) cm(-2).eV(-1) and 9x10(10) cm(-2).eV(-1) from 0.9 Ev to 0.2 eV below Ec) and sigma(s) value (60 mV) were slightly lower for thick PVT layers. A discrepancy in the Dit values obtained from C-V and G-V measurements is attributed to the large surface potential standard deviation. Results from an original oxide growth process using a deposited sacrificial silicon layer under UHV conditions are also presented.

  • 2074.
    Zimmermann, F.
    et al.
    TU Bergakad Freiberg, Germany.
    Beyer, Franziska
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Gaertner, G.
    TU Bergakad Freiberg, Germany.
    Roeder, C.
    TU Bergakad Freiberg, Germany.
    Nguyen, Son Tien
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Vesela, D.
    Research Centre Rez, Czech Republic.
    Lorincik, J.
    Research Centre Rez, Czech Republic.
    Hofmann, P.
    NaMLab gGmbH, Germany.
    Krupinski, M.
    NaMLab gGmbH, Germany.
    Mikolajick, T.
    NaMLab gGmbH, Germany; Technical University of Dresden, Germany.
    Habel, F.
    Freiberger Compound Mat GmbH, Germany.
    Leibiger, G.
    Freiberger Compound Mat GmbH, Germany.
    Heitmann, J.
    TU Bergakad Freiberg, Germany.
    Origin of orange color in nominally undoped HVPE GaN crystals2017In: Optical materials (Amsterdam), ISSN 0925-3467, E-ISSN 1873-1252, Vol. 70, p. 127-130Article in journal (Refereed)
    Abstract [en]

    In this article we investigated unintentionally doped (UID) GaN grown by hydride vapor phase epitaxy (HVPE) with respect to point defects and impurity concentration. The samples were orange tinted to different extent. Optical analysis was performed by micro-photoluminescence and absorption spectroscopy. Absorption measurements revealed an absorption peak at 1.5 eV related to an internal transition in Mn3+ impurities and a second band with low energy onset at 1.9 eV, both increasing with the extent of orange color. Electron paramagnetic resonance investigations showed the presence of Mn2+ and Fe3+ in the colored crystals. The overall impurity concentration was verified by secondary ion mass spectrometry. Orange tint is associated with an increase of transition metal contamination, especially Mn. Based on these observations we suggest that the orange coloring in the investigated UID HVPE GaN samples is caused by the presence of Mn impurities. (C) 2017 Elsevier B.V. All rights reserved.

  • 2075.
    Zimmermann, U
    et al.
    Royal Inst Technol, Dept Microelect & Informat Technol, SE-16440 Kista, Sweden Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Osterman, J
    Royal Inst Technol, Dept Microelect & Informat Technol, SE-16440 Kista, Sweden Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Zhang, J
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Hallen, A
    Royal Inst Technol, Dept Microelect & Informat Technol, SE-16440 Kista, Sweden Linkoping Univ, Dept Phys & Measurement Technol, S-58183 Linkoping, Sweden.
    Electrical characterization of high-voltage 4H-SiC diodes on high-temperature CVD-grown epitaxial layers2002In: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, p. 1285-1288Conference paper (Refereed)
    Abstract [en]

    High-temperature chemical vapour deposition (HTCVD) in a vertical chimney reactor was used to grow thick low-doped epitaxial layers of 4H silicon carbide. These layers were used as drift layers in a combined process to manufacture both bipolar and unipolar high-voltage diodes. The resulting diodes were characterized electrically in order to gain knowledge about the electric quality of the HTCVD epitaxial layers to assess the high-voltage properties of this material.

  • 2076. Zolnai, Z.
    et al.
    Nguyen, Son Tien
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Magnusson, Björn
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Hallin, Christer
    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.
    Annealing behaviour of vacancy- and antisite-related defects in electron-irradiated 4H-SiC2004In: Mater. Sci. Forum, Vol. 457-460, Trans Tech Publications Inc. , 2004, p. 473-Conference paper (Refereed)
  • 2077.
    Zoulis, G.
    et al.
    CNRS, Montpellier, France.
    Sun, Jianwu
    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.
    Lorenzzi, J.
    Laboratoire des Multimateriaux et Interfaces, University Claude Bernard Lyon 1, Villeurbanne, France.
    Peyre, H.
    Université Montpellier 2, France.
    Syväjärvi, Mikael
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ferro, G.
    Laboratoire des Multimateriaux et Interfaces, University Claude Bernard Lyon 1, Villeurbanne, France.
    Juillaguet, S.
    Université Montpellier 2, France.
    Yakimova, Rositza
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Camassel, J.
    CNRS, Montpellier, France .
    Seeding layer influence on the low temperature photoluminescence intensity of 3C-SiC grown on 6H-SiC by sublimation epitaxy2012In: HETEROSIC and WASMPE 2011 / [ed] Daniel Alquier, Trans Tech Publications Inc., 2012, Vol. 711, p. 149-153Conference paper (Refereed)
    Abstract [en]

    We report on n-type 3C-SiC samples grown by sublimation epitaxy. We focus on the low temperature photoluminescence intensity and show that the presence of a first conversion layer, grown at low temperature, is not only beneficial to improve the homogeneity of the polytype conversion but, also, to the LTPL signal intensity. From the use of a simple model, we show that this comes from a reduced density of non-radiative recombination centers.

  • 2078.
    Zoulis, Georgios
    et al.
    Groupe d’Etudes des Semiconducteurs, Université Montpellier 2 and CNRS, cc 074‐GES, 34095 Montpellier Cedex 5, France.
    Sun, Jian Wu
    Groupe d’Etudes des Semiconducteurs, Université Montpellier 2 and CNRS, cc 074‐GES, 34095 Montpellier Cedex 5, France.
    Beshkova, Milena
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Vasiliauskas, Remigijus
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Juillaguet, S.
    Groupe d’Etudes des Semiconducteurs, Université Montpellier 2 and CNRS, cc 074‐GES, 34095 Montpellier Cedex 5, France.
    Peyre, H.
    Groupe d’Etudes des Semiconducteurs, Université Montpellier 2 and CNRS, cc 074‐GES, 34095 Montpellier Cedex 5, France.
    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.
    Camassel, J.
    Groupe d’Etudes des Semiconducteurs, Université Montpellier 2 and CNRS, cc 074‐GES, 34095 Montpellier Cedex 5, France.
    Investigation of Low Doped n-Type and p-Type 3C-SiC Layers Grown on 6H-SiC Substrates by Sublimation Epitaxy2010In: Silicon Carbide and Related Materials 2009, 2010, Vol. 645, p. 179-182Conference paper (Refereed)
    Abstract [en]

    Both, n-type and p-type 3C-SiC samples grown on 6H-SiC substrates by sublimation epitaxy have been investigated. From low temperature photoluminescence studies, we demonstrate a low level of residual (n and/or p-type) doping with weak compensation, which is confirmed by secondary ion mass spectroscopy in the case of p-type samples.

  • 2079.
    Ščajev, Patrik
    et al.
    Institute of Applied Research, Vilnius University, Vilnius, Lithuania.
    Hassan, Jawad
    Institute of Applied Research, Vilnius University, Vilnius, Lithuania.
    Jarašiūnas, Kęstutis
    Institute of Applied Research, Vilnius University, Vilnius, Lithuania.
    Kato, Masashi
    Nagoya Institute of Technology, Gokiso, Showa-ku, Nagoya, Japan.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Bergman, J Peder
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Comparative Studies of Carrier Dynamics in 3C-SiC Layers Grown on Si and 4H-SiC Substrates2011In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 40, no 4, p. 394-399Article in journal (Refereed)
    Abstract [en]

    Time-resolved nonlinear optical techniques were applied to determine the electronic parameters of cubic silicon carbide layers. Carrier lifetime, tau, and mobility, mu, were measured in a free-standing wafer grown on undulant Si and an epitaxial layer grown by hot-wall chemical vapor deposition (CVD) on a nominally on-axis 4H-SiC substrate. Nonequilibrium carrier dynamics was monitored in the 80 K to 800 K range by using a picosecond free carrier grating and free carrier absorption techniques. Correlation of tau(T) and mu (a)(T) dependencies was explained by the strong contribution of diffusion-limited recombination on extended defects in the layers. A lower defect density in the epitaxial layer on 4H-SiC was confirmed by a carrier lifetime of 100 ns, being similar to 4 times longer than that in free-standing 3C.

  • 2080.
    Žukauskaitė, Agnė
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Tholander, Christopher
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Pališaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O. Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Ben Sedrine, Nebiha
    Instituto Tecnológico e Nuclear, 2686-953 Sacavém and CFNUL, Lisbon 1649-003, Portugal.
    Tasnádi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    YxAl1-xN Thin Films2012In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 45, no 42, p. 422001-Article in journal (Refereed)
    Abstract [en]

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

39404142 2051 - 2080 of 2080
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