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  • 1.
    Buchholt, Kristina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ghandi, R
    Royal Institute Technology, KTH.
    Domeij, M
    Royal Institute Technology, KTH.
    Zetterling, C M
    Royal Institute Technology, KTH.
    Behan, G
    Trinity College Dublin.
    Zhang, H
    Trinity College Dublin.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied 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.
    Growth and characterization of epitaxial Ti3GeC2 thin films on 4H-SiC(0001)2012In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 343, no 1, 133-137 p.Article in journal (Refereed)
    Abstract [en]

    Epitaxial Ti3GeC2 thin films were deposited on 4 degrees off-cut 4H-SiC(0001) using magnetron sputtering from high purity Ti, C, and Ge targets. Scanning electron microscopy and helium ion microscopy show that the Ti3GeC2 films grow by lateral step-flow with {11 (2) over bar0} faceting on the SiC surface. Using elastic recoil detection analysis, atomic force microscopy, and X-Ray diffraction the films were found to be substoichiometric in Ge with the presence of small Ge particles at the surface of the film.

  • 2.
    Buyanova, Irina
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Chen, Weimin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials.
    Bi, W. G.
    Zeng, Y. P.
    Tu, C. W.
    Intrinsic modulation doping in InP-based structures: properties relevant to device applications1999In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 201-202, 786-789 p.Article in journal (Refereed)
    Abstract [en]

     In this work we study device-relevant issues, such as doping efficiency and thermal stability, of recently proposed intrinsic modulation doping approach where intrinsic defects (PIn antisites) are used as a carrier source instead of impurity dopants. The InP/InGaAs heterostructure designed to resemble high electron mobility transistor (HEMT) structures, where all the layers were grown at a normal growth temperature 480°C except for the top InP layer which was grown at 265°C, was used as a prototype device. A comparison between the intrinsically doped structure with extrinsically doped HEMTs, which have an identical design except that the top InP layer was instead Si-doped and was grown at 480°C, reveals a high efficiency of the intrinsic doping. The thermal stability of the intrinsically doped HEMT is examined by annealing at temperatures 400-500°C relevant to possible processing steps needed in device fabrication. The observed severe reduction of the carrier concentration after annealing performed without phosphorous gas protection is attributed to the known instability of an InP surface at T>400°C. Thermal stability of the intrinsically doped HEMT is shown to be improved by using an InP cap layer grown at 480°C.

  • 3.
    Chen, Jr-Tai
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pomeroy, James W.
    Center for Device Thermography and Reliability, H.H. Wills Physics Laboratory, University of Bristol, UK.
    Rorsman, Niklas
    Microwave Electronics Laboratory, MC2, Chalmers University of Technology, Göteborg, Sweden.
    Xia, Cha
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Virojanadara, Chariya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kuball, Martin
    Center for Device Thermography and Reliability, H.H. Wills Physics Laboratory, University of Bristol, UK.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Low thermal resistance of a GaN-on-SiC transistor structure with improved structural properties at the interface2015In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 428, 54-58 p.Article in journal (Refereed)
    Abstract [en]

    The crystalline quality of AlGaN/GaN heterostructures was improved by optimization of surface pretreatment of the SiC substrate in a hot-wall metal-organic chemical vapor deposition reactor. X-ray photoelectron spectroscopy measurements revealed that oxygen- and carbon-related contaminants were still present on the SiC surface treated at 1200 °C in H2 ambience, which hinders growth of thin AlN nucleation layers with high crystalline quality. As the H2 pretreatment temperature increased to 1240 °C, the crystalline quality of the 105 nm thick AlN nucleation layers in the studied series reached an optimal value in terms of full width at half-maximum of the rocking curves of the (002) and (105) peaks of 64 and 447 arcsec, respectively. The improvement of the AlN growth also consequently facilitated a growth of the GaN buffer layers with high crystalline quality. The rocking curves of the GaN (002) and (102) peaks were thus improved from 209 and 276 arcsec to 149 and 194 arcsec, respectively. In addition to a correlation between the thermal resistance and the structural quality of an AlN nucleation layer, we found that the microstructural disorder of the SiC surface and the morphological defects of the AlN nucleation layers to be responsible for a substantial thermal resistance. Moreover, in order to decrease the thermal resistance in the GaN/SiC interfacial region, the thickness of the AlN nucleation layer was then reduced to 35 nm, which was shown sufficient to grow AlGaN/GaN heterostructures with high crystalline quality. Finally, with the 35 nm thick high-quality AlN nucleation layer a record low thermal boundary resistance of 1.3×10−8 m2 K/W, measured at an elevated temperature of 160 °C, in a GaN-on-SiC transistor structure was achieved.

  • 4.
    Danielsson, Örjan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Henry , Anne
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Investigation of the temperature profile in a hot-wall SiC chemical vapour deposition reactor2002In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 235, no 1-4, 352-364 p.Article in journal (Refereed)
    Abstract [en]

    The chemical vapor deposition (CVD) technique is widely used to grow epitaxial layers of silicon carbide. To meet the demands for high quality epitaxial layers, which have good morphology and a minimum variation of the doping and thickness, a good knowledge of the CVD process is essential. The present work uses a simulation tool to investigate several parameters influencing the heating of <!--[if !vml]--><!--[endif]-->a hot-wall CVD reactor. The simulations are set up as 2D axisymmetric problems and validation is made in a 2D horizontal hot-wall CVD reactor. By applying the knowledge achieved from the simulations, the temperature profile is optimized to give as large area as possible with homogeneous temperature. New susceptor and coil designs are tested. A very good agreement between the simulated and the measured results is obtained. The new design has a temperature variation of less than 0.5% over more than 70% of the total susceptor length at an operating temperature of 1650°C. In addition, the power input needed to reach the operating temperature is decreased by 15% compared to the original design. 3D simulations are performed to show that the changes made in the 2D case give similar results for the real 3D case.

  • 5.
    Danielsson, Örjan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Predicted nitrogen doping concentrations in silicon carbide epitaxial layers grown by hot-wall chemical vapor deposition2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 250, no 3-4, 471-478 p.Article in journal (Refereed)
    Abstract [en]

    A simple quantitative model for the surface adsorption of nitrogen has been developed to simulate the doping incorporation in intentionally doped 4H-SiC samples during epitaxial growth. Different reaction schemes are necessary for the two faces of SiC. The differences are discussed, and implications to the necessary model adjustments are stressed. The simulations are validated by experimental values for a large number of different process parameters with good agreement.

  • 6.
    Danielsson, Örjan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hallin, Christer
    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.
    Reducing stress in silicon carbide epitaxial layers2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 252, no 1-3, 289-296 p.Article in journal (Refereed)
    Abstract [en]

    A susceptor for the epitaxial growth of silicon carbide, with an up-lifted substrate holder, is investigated and compared to other susceptor designs both experimentally and by the use of computational fluid dynamics simulations. It is shown that the wafer bending due to temperature gradients is diminished in a hot-wall reactor compared to growth in a cold-wall reactor. The substrate backside growth is diminished using the up-lifted substrate holder, limiting the substrate bending due to the backside growth. Thereby the stress built into the epitaxial layers during growth is significantly reduced. Simulations indicate a lower effective C/Si ratio over the wafer, and a lower preferable growth temperature, as compared to the original susceptor design. In addition a slightly higher growth rate is achieved

  • 7.
    Danielsson, Örjan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Growth rate predictions of chemical vapor deposited silicon carbide epitaxial layers2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 243, no 1, 170-184 p.Article in journal (Refereed)
    Abstract [en]

    Complete 3D simulations of a silicon carbide chemical vapor deposition (CVD) reactor, including inductive heating and fluid dynamics as well as gas phase and surface chemistry, have been performed. For the validation of simulated results, growth was conducted in a horizontal hot-wall CVD reactor operating at 1600°C, using SiH4 and C3H8 as precursor gases. Simulations were performed for an experimental hot-wall CVD reactor, but the results are applicable to any reactor configuration since no adjustable parameters were used to fit experimental data. The simulated results obtained are in very good agreement with experimental values. It is shown that including etching and parasitic growth on all reactor walls exposed to the gas greatly improves the accuracy of the simulations. © 2002 Elsevier Science B.V. All rights reserved.

  • 8.
    Danielsson, Örjan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Using N2 as precursor gas in III-nitride CVD growth2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 253, no 1-4, 26-37 p.Article in journal (Refereed)
    Abstract [en]

    Computational fluid dynamics simulations have been performed to explore the possibility of using nitrogen gas as a precursor to III-nitride growth. A chemical model for the gas-phase decomposition of N2 has been used to show that large enough amounts of reactive species can be formed under conditions not far from those used in normal metalorganic chemical vapor deposition. Simulations were performed in 2D for various concentrations of N2, and comparisons with the use of NH3 were made. A modified reactor design needed to achieve high enough concentrations of reactive species is suggested. The possibility to increase the growth rate and material quality in III-nitride growth is discussed.

  • 9.
    Darakchieva, Vanya
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Usui, A.
    R and D Division, Furukawa Co. Ltd., Tsukuba, Ibaraki, 305-0865, Japan.
    Saenger, M.
    Department of Electrical Engineering, University of Nebraska, Lincoln, NE 68588, United States.
    Schubert, M.
    Department of Electrical Engineering, University of Nebraska, Lincoln, NE 68588, United States.
    Lattice parameters of bulk GaN fabricated by halide vapor phase epitaxy2008In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 310, no 5, 959-965 p.Article in journal (Refereed)
    Abstract [en]

    The lattice parameters of low-defect density undoped bulk GaN fabricated by halide vapor phase epitaxy (HVPE) and removal of the substrate are precisely determined using high-resolution X-ray diffraction. The obtained values, c = 5.18523 over(A, °) and a = 3.18926 over(A, °) are compared with the lattice parameters of free-standing HVPE-GaN from different sources and found to be representative for state-of-the-art undoped HVPE bulk GaN material. A comparison with bulk GaN fabricated by the high pressure technique and homoepitaxial GaN layer is made, and the observed differences are discussed in terms of their free-electron concentrations, point and structural defects. © 2007 Elsevier B.V. All rights reserved.

  • 10.
    Darakchieva, Vanya
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskova, T.
    Institute of Solid State Physics, University of Bremen, 28359 Bremen, Germany.
    Schubert, M.
    Department of Electrical Engineering, University of Nebraska, Lincoln, NE 68588, United States.
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Arwin, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hommel, D.
    Institute of Solid State Physics, University of Bremen, 28359 Bremen, Germany.
    Heuken, M.
    Aixtron AG, D-52072 Aachen, Germany.
    Off, J.
    Institute of Physics 4, University of Stuttgart, 70569 Stuttgart, Germany.
    Haskell, B.A.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Fini, P.T.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Speck, J.S.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Nakamura, S.
    Materials Department, University of California, Santa Barbara, CA 93106, United States.
    Effect of anisotropic strain on phonons in a-plane and c-plane GaN layers2007In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 300, no 1, 233-238 p.Article in journal (Refereed)
    Abstract [en]

    We have studied phonons in two types of anisotropically strained GaN films: c-plane GaN films grown on a-plane sapphire and a-plane GaN films grown on r-plane sapphire. The anisotropic strain in the films is determined by high-resolution X-ray diffraction (HRXRD) in different measuring geometries and the phonon parameters have been assessed by generalized infrared spectroscopic ellipsometry (GIRSE). The effect of strain anisotropy on GaN phonon frequencies is presented and the phonon deformation potentials aA1 (TO), bA1 (TO), cE1 (TO) and cE1 (LO) are determined. © 2006 Elsevier B.V. All rights reserved.

  • 11.
    Eklund, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Murugaiah, Anand
    Department of Materials Science and Engineering, Drexel University, Philadelphia, USA.
    Emmerlich, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Czigany, Zsolt
    Research Institute for Technical Physics and Materials Science, Hungarian Academy of Sciences, Budapest, Hungary.
    Frodelius, Jenny
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Barsoum, Michel W.
    Department of Materials Science and Engineering, Drexel University, Philadelphia, USA.
    Högberg, Hans
    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.
    Homoepitaxial growth of Ti-Si-C MAX-phase thin films on bulk Ti3SiC2 substrates2007In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 304, no 1, 264-269 p.Article in journal (Refereed)
    Abstract [en]

    Ti3SiC2 films were grown on polycrystalline Ti3SiC2 bulk substrates using DC magnetron sputtering. The crystallographic orientation of the film grains is shown to be determined by the respective substrate-grain orientation through homoepitaxial MAX-phase growth. For a film composition close to Ti:Si:C=3:1:2, the films predominantly consist of MAX phases, both Ti3SiC2 and the metastable Ti4SiC3. Lower Si content resulted in growth of TiC with Ti3SiC2 as a minority phase. Thus, MAX-phase heterostructures with preferred crystallographic relationships can also be realized.

  • 12. Ellison, A.
    et al.
    Zhang, J.
    Henry, Anne
    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 .
    Epitaxial growth of SiC in a chimney CVD reactor2002In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 236, no 1-3, 225-238 p.Article in journal (Refereed)
    Abstract [en]

    A high growth rate (>10 µm/h) Chemical Vapour Deposition (CVD) process is investigated in a vertical hot-wall, or "chimney", reactor. By the use of increased temperatures (1650-1850°C) and concentrations of reactants, this process is shown to enable growth rates up to 50µm/h and demonstrates a material quality comparable to established CVD techniques until growth rates of 25 µm/h. The gas flow dynamics, the growth rate and the thickness uniformity determining steps are investigated, and the role of homogenous nucleation is analysed. The growth rate is shown to be influenced by two competing processes: the supply of growth species and the etching of the hydrogen carrier gas. The exponential increase of the growth rate with temperature is related to a Si-vapour release from clusters homogeneously nucleated in the inlet of the susceptor and acting as a growth species reservoir. © 2002 Elsevier Science B.V. All rights reserved.

  • 13. Falth, JF
    et al.
    Gurusinghe, MN
    Liu, XY
    Andersson, TG
    Ivanov, Ivan Gueorguiev
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Yao, HH
    Wang, SC
    Influence of dislocation density on photoluminescence intensity of GaN2005In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 278, no 01-Apr, 406-410 p.Article in journal (Refereed)
    Abstract [en]

    The influence of dislocation density on photoluminescence intensity is investigated experimentally and compared to a model. GaN samples were grown by molecular beam epitaxy and metal-organic chemical vapour deposition. Different growth parameters and thicknesses of the layers resulted in different dislocation densities. The threading dislocation density, measured by atomic force microscopy, scanning electron microscopy and X-ray diffraction, covered a range from 5 x 10(8) to 3 x 10(10) cm(-2). Carrier concentration was measured by capacitance-voltage-, and Hall effect measurements and photoluminescence at 2 K was recorded. A model which accounts for the photoluminescence intensity as a function of dislocation density and carrier concentration in GaN is developed. The model shows good agreement with experimental results for typical GaN dislocation densities, 5 x 10(8)-1 x 10(10) cm(-2), and carrier concentrations 4 x 10(16)-1 x 10(18) cm(-3). ©, 2005 Elsevier B.V. All rights reserved.

  • 14.
    Fernandez, J.R.L.
    et al.
    Instituto De Física, Universidade De São Paulo, CP66318, 05315-970 São Paulo, SP, Brazil.
    Moyses, Araujo C.
    Moysés Araújo, C., Instituto De Física, Universidade Federal Da Bahia, Campus Universitário De Ondina, 40210-340 Salvador, Bahia, Brazil.
    Ferreira, Da Silva A.
    Ferreira Da Silva, A., Instituto De Física, Universidade Federal Da Bahia, Campus Universitário De Ondina, 40210-340 Salvador, Bahia, Brazil.
    Leite, J.R.
    Instituto De Física, Universidade De São Paulo, CP66318, 05315-970 São Paulo, SP, Brazil.
    Sernelius, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Tabata, A.
    Instituto De Física, Universidade De São Paulo, CP66318, 05315-970 São Paulo, SP, Brazil.
    Abramof, E.
    Instituto Nacional De Pesquisas Espaciais (INPE-LAS), CP 515, 12201-970 Sao Jose dos Campos, SP, Brazil.
    Chitta, V.A.
    Instituto De Física, Universidade De São Paulo, CP66318, 05315-970 São Paulo, SP, Brazil.
    Persson, C.
    Department of Physics, Uppsala University, SE-751 21 Uppsala, Sweden.
    Ahuja, R.
    Department of Physics, Uppsala University, SE-751 21 Uppsala, Sweden.
    Pepe, I.
    Instituto De Física, Universidade Federal Da Bahia, Campus Universitário De Ondina, 40210-340 Salvador, Bahia, Brazil.
    As, D.J.
    Universität Paderborn, FB-6 Physik, D-33095 Paderborn, Germany.
    Frey, T.
    Universität Paderborn, FB-6 Physik, D-33095 Paderborn, Germany.
    Schikora, D.
    Universität Paderborn, FB-6 Physik, D-33095 Paderborn, Germany.
    Lischka, K.
    Universität Paderborn, FB-6 Physik, D-33095 Paderborn, Germany.
    Electrical resistivity and band-gap shift of Si-doped GaN and metal-nonmetal transition in cubic GaN, InN and AlN systems2001In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 231, no 3, 420-427 p.Conference paper (Other academic)
    Abstract [en]

    The critical impurity concentration Nc of the metal-nonmetal (MNM) transition for the cubic GaN, InN and AlN systems, is calculated using the following two different criteria: vanishing of the donor binding energy and the crossing point between the energies in the metallic and insulating phases. A dielectric function model with a Lorentz-Lorenz correction is used for the insulating phase. The InN presents an order of magnitude increase in Nc as compared to the other two systems. The electrical resistivity of the Si-donor system GaN is investigated theoretically and experimentally from room temperature down to 10 K. It presents a metallic character above a certain high impurity concentration identified as Nc. The samples were grown by plasma assisted molecular beam epitaxy (MBE) on GaAs (0 0 1) substrate. The model calculation is carried out from a recently proposed generalized Drude approach (GDA) presenting a very good estimation for the metallic region. The band-gap shift (BGS) of Si-doped GaN has also been investigated above the MNM transition where this shift is observed. Theoretical and experimental results have a rough agreement in a range of impurity concentration of interest. © 2001 Elsevier Science B.V. All rights reserved.

  • 15. Figge, S
    et al.
    Bottcher, T
    Dennemarck, J
    Kroger, R
    Paskova, Tanja
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hommel, D
    Optoelectronic devices on bulk GaN2005In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 281, no 1, 101-106 p.Article in journal (Refereed)
    Abstract [en]

    The homoeptaxial fabrication of GaN-based devices has advantages against heteroepitaxial realization on substrates such as sapphire or SiC, since heteroepitaxy implies a lot of problems like lattice mismatch, different thermal expansion coefficients, and needs an extensive optimization of the growth at the heterointerface. In this paper we will discuss GaN-based light-emitting devices grown by homoepitaxy in comparison to devices grown on sapphire. A special emphasis is laid on the pretreatment of the GaN substrate and the device characteristics on different substrates. In detail will be discussed the advantages of the higher thermal conductivity of GaN and how this effects the device performance. (c) 2005 Elsevier B.V. All rights reserved.

  • 16.
    Fornari, R.
    et al.
    Leibniz-Institute for Crystal Growth, Institute of Physics, Humboldt University, Berlin, Germany.
    Carlos, Rojo J.
    Carlos Rojo, J., General Electric Global Research, NY, United States.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Preface2008In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 310, no 5, 875 p.875-875 p.Article in journal (Other academic)
  • 17.
    Forsberg, Urban
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Danielsson, Örjan
    Linköping University, Department of Physics, Chemistry and Biology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Linnarsson, M. K.
    Solid State Electronics, Royal Institute of Technology, SE-164 40 Kista, Sweden.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Nitrogen doping of epitaxial Silicon Carbide2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 236, no 1-3, 101-112 p.Article in journal (Refereed)
    Abstract [en]

    Intentional doping with nitrogen of 4H- and 6H-SiC has been performed using a hot-wall CVD reactor. The nitrogen doping dependence on the temperature, pressure, C/Si ratio, growth rate and nitrogen flow has been investigated. The nitrogen incorporation for C-face material showed to be C/Si ratio independent, whereas the doping decreased with increasing C/Si ratio for the Si-face material in accordance with the “site-competition” model. The nitrogen incorporation was constant in a temperature “window” of 75°C on Si-face material indicating a mass transport limited incorporation. Increasing the growth rate resulted in a decrease of nitrogen incorporation on Si-face but an increase on C-face material. Finally, a comparison between previously published results on cold-wall CVD-grown material and the present hot-wall-grown material is presented.

  • 18.
    Forsberg, Urban
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Danielsson, Örjan
    Linköping University, Department of Physics, Chemistry and Biology.
    Henry, Anne
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Linnarsson, M. K.
    Solid State Electronics, Royal Institute of Technology, SE-164 40, Kista, Sweden.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Aluminum doping of epitaxial Silicon Carbide2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 253, no 1-4, 340-350 p.Article in journal (Refereed)
    Abstract [en]

    Intentional doping of aluminum in 4H and 6H SiC has been performed using a hot-wall CVD reactor. The dependence of aluminum incorporation on temperature, pressure, C/Si ratio, growth rate, and TMA flow has been investigated. The aluminum incorporation showed to be polarity dependent. The high aluminum incorporation on the Si-face is closely related to the carbon coverage on the SiC surface. Changes in process parameters changes the effective C/Si ratio close to the SiC surface. Increased growth rate and C/Si ratio increases the aluminum incorporation on the Si-face. Diffusion limited incorporation occurs at high growth rate. Reduced pressure increases the effective C/Si ratio, and at low growth rate, the aluminum incorporation increases initially, levels off at a critical pressure, and continues to decrease below the critical pressure. The aluminum incorporation showed to be constant in a temperature range of 50°C. The highest atomic concentration of aluminum observed in this study was 3×1017 and 8×1018 cm−3 in Si and C-face, respectively.

  • 19.
    Forsberg, Urban
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Lundskog, Anders
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Ciechonski, Rafal
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Improved hot-wall MOCVD growth of highly uniform AlGaN/GaN/HEMT structures2009In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 311, no 10, 3007-3010 p.Article in journal (Refereed)
    Abstract [en]

    The inherent advantages of the hot-wall metal organic chemical vapor deposition (MOCVD) reactor (low temperature gradients, less bowing of the wafer during growth, efficient precursor cracking) compared to a cold-wall reactor make it easier to obtain uniform growth. However, arcing may occur in the growth chamber during growth, which deteriorates the properties of the grown material. By inserting insulating pyrolytic BN (PBN) stripes in the growth chamber we have completely eliminated this problem. Using this novel approach we have grown highly uniform, advanced high electron mobility transistor (HEMT) structures on 4 semi-insulating (SI) SiC substrates with gas-foil rotation of the substrate. The nonuniformities of sheet resistance and epilayer thickness are typically less than 3% over the wafer. The room temperature hall mobility of the 2DEG is well above 2000 cm(2)/V s and the sheet resistance about 270 Omega/sqr.

  • 20.
    Godlewski, M.
    et al.
    Institute of Physics, Pol. Acad. Sci., Al. L., Warsaw, Poland.
    Narkowicz, R.
    Institute of Physics, Pol. Acad. Sci., Al. L., Warsaw, Poland, Semiconductor Physics Institute, A. Gostauto 11, LT-2600, Vilnius, Lithuania.
    Wojtowicz, T.
    Institute of Physics, Pol. Acad. Sci., Al. L., Warsaw, Poland.
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Quasi-zero-dimensional excitons in quantum well structures of CdTe/CdMnTe2000In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 214, 420-423 p.Article in journal (Refereed)
    Abstract [en]

    In this work we discuss properties of excitons in quantum well structures of CdTe/CdMnTe. We analyse exciton-phonon interaction of strongly localised excitons by studying the temperature dependence of photoluminescence (PL) (width and spectral position of PL lines) and PL dynamics. Evidence of a slow exciton migration/tunnelling among localised sites is presented and its effect on the luminescence spectrum and exciton dynamics is discussed. We show that strong localisation of excitons, observed at low temperatures, results in quasi-zero-dimensional nature of excitons.

  • 21.
    Gray, Ciaran
    et al.
    Dublin City University, Ireland.
    Cullen, Joseph
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, The Institute of Technology.
    Byrne, Conor
    Dublin City University, Ireland.
    Hughes, Greg
    Dublin City University, Ireland.
    Buyanova, Irina
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Chen, Weimin
    Linköping University, Department of Physics, Chemistry and Biology, Functional Electronic Materials. Linköping University, Faculty of Science & Engineering.
    Henry, Martin O.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Dublin City University, Ireland.
    McGlynn, Enda
    Dublin City University, Ireland.
    Growth of isotopically enriched ZnO nanorods of excellent optical quality2015In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 429Article in journal (Refereed)
    Abstract [en]

    We have produced isotopically enriched ZnO nanorods using Zn-enriched ZnO source powder by vapour phase transport on silicon substrates buffer coated with unenriched ZnO seed layers. SEM and XRD data confirm successful growth of high quality, dense, c-axis aligned nanorods over a substantial surface area. Raman. data show a shift of greater than 1 cm(-1) in the peak position of the Raman scattered peaks due to the E-2(low) and E-2(high) phonon modes when the Zn isotope is changed from Zn-64 to Zn-68, consistent with previous work, thus confirming successful isotopic enrichment. SIMS data provides additional confirmation of enrichmenr. The optical qualiry (as dererrninecl by phoLoluminescence feature inrensiLy and line width) is excellenr. Samples with Zn isoLopic enrichmenr ranging from (ZnO)-Zn-64 to (ZnO)-Zn-68 display a shift in recombinarion energy of the bound excirons al. the band edge (3.34-3.37 eV) of similar to 0.6 meV. This blue-shift is also consisren d. with previously published data, further confirming both the excellen d. oprical qualiry and successful isoLopic subsfiLurion of ZnO nanorods using this relarively simple growth method. (c) 2015 Elsevier B.V. All rights reserved.

  • 22.
    Hemmingsson, Carl
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Paskov, Plamen
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Heuken, M.
    Aixtron AG, D-52072 Aachen, Germany.
    Schineller, B.
    Aixtron AG, D-52072 Aachen, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Hydride vapour phase epitaxy growth and characterization of thick GaN using a vertical HVPE reactor2007In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 300, no 1, 32-36 p.Article in journal (Refereed)
    Abstract [en]

    Growth of 2-inch diameter bulk GaN layers with a thickness up to 2 mm is demonstrated in a vertical hydride vapour phase growth reactor. Morphology, dislocations, optical and electrical properties of the material have been investigated using atomic force microscopy, optical microscopy, decorative etching in hot H3PO4, Hall measurements and low-temperature photoluminescence. Atomic force microscopy reveals a two-dimensional step flow growth mode with step bunching for layers with a thickness of 250 µm. As the growth proceeds, the morphology is changed to a hill and valley structure. The EPD was determined to 5×105 cm-2 for a 2 mm thick layer. The Hall mobility and the carrier concentration were determined. For a 1.7 mm thick layer at 300 K the mobility and the carrier concentration is 520 cm2/V s and about 4×1017 cm-3, respectively. Low-temperature photoluminescence spectra measured on a 350 µm thick freestanding layer show the DBE line at 3.4707 eV with a full-width half-maximum of 1 meV, confirming a stress free GaN layer. © 2006 Elsevier B.V. All rights reserved.

  • 23.
    Hemmingsson, Carl
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Optimization of low temperature GaN buffer layers for halide vapor phase epitaxy growth of bulk GaN2013In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 366, 61-66 p.Article in journal (Refereed)
    Abstract [en]

    We have studied growth and self-separation of bulk GaN on c-oriented Al2O3 using low temperature (LT) GaN buffer layers. By studying the X-ray diffraction (XRD) signature for the asymmetric and symmetric reflections versus the LT-GaN thickness and V/III precursor ratio, we observe that the peak width of the reflections is minimized using a LT buffer thickness of ∼100–300 nm. It was observed that the V/III precursor ratio has a strong influence on the morphology. In order to obtain a smooth morphology, the V/III precursor ratio has to be more than 17 during the growth of the buffer layer. By using an optimized LT buffer layer for growth of a 20 μm thick GaN layer, we obtain a XRD peak with a full width at half maximum of ∼400 and ∼250 arcs for (002) and (105) reflection planes, respectively, and with a dark pit density of ∼2.2×108 cm−2. For layers thicker than 1 mm, the GaN was spontaneously separated and by utilizing this process, thick free freestanding 2″ GaN substrates were manufactured.

  • 24.
    Hemmingsson, Carl
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Heuken, M.
    Aixtron AG, D-52072 Aachen, Germany.
    Schineller, B.
    Aixtron AG, D-52072 Aachen, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Modeling, optimization, and growth of GaN in a vertical halide vapor-phase epitaxy bulk reactor2008In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 310, no 5, 906-910 p.Article in journal (Refereed)
    Abstract [en]

    In this work we are presenting growth results of thick gallium nitride (GaN), numerical modeling and optimization of a vertical hot-walled halide vapor-phase epitaxy reactor. Using a simulation model, the growth rate and thickness uniformity of the GaN layers have been predicted and optimized. The simulation results have been correlated with experiments to verify the model. Using constant precursor flows, the average growth rate over a 2 in substrate was increased with a factor of four by only optimizing the composition of N2 and H2 in the carrier gas and the carrier gas flow rates. With a simple sticking model, assuming Ga mass transport-limited growth, the growth rate and thickness uniformity could be estimated. Photoluminescence mapping of the grown layer shows that the layers have excellent optical properties and a high degree of uniformity. © 2007 Elsevier B.V. All rights reserved.

  • 25.
    Hermann, M.
    et al.
    Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany.
    Gogova, D.
    Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin, Germany, Central Lab of Solar Energy at the Bulgarian Acad. Sci., Blvd. Tzarigradsko shose 72, 1784 Sofia, Bulgaria.
    Siche, D.
    Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin, Germany.
    Schmidbauer, M.
    Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin, Germany.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Stutzmann, M.
    Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany.
    Eickhoff, M.
    Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany.
    Nearly stress-free substrates for GaN homoepitaxy2006In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 293, no 2, 462-468 p.Article in journal (Refereed)
    Abstract [en]

    High-quality 300 µm thick GaN crack-free layers grown by hydride vapor phase epitaxy (HVPE) on c-plane sapphire without buffer layers and separated from the substrate by laser lift-off were investigated by high resolution X-ray diffraction (XRD), low-temperature photoluminescence and cathodoluminescence. All these characterization techniques confirm the high structural quality of the resulting material. Lateral X-ray mapping of the free-standing bulk-like GaN shows a homogeneous compressive stress of less than 40 MPa and a heterogeneous stress of about 80 MPa. The formation of twin grains (domains) were observed both in the reciprocal space mapping of the (2 0 .5) reflection and in rocking curve measurements. The latter ones revealed an estimated lateral coherence length of about 1.2 µm. The crystallite size along the c-axis is estimated to be larger than 20 µm. An upper limit of the density of dislocations with a component of the Burgers vector along the c-axis (screw and mixed type) of 1.3×107 cm-2 was extracted from the XRD data, while transmission electron microscopy measurements revealed a dislocation density of 1.7×107 cm-2. Thus, these layers are suitable as lattice-parameter and thermal-expansion matched substrates for strain-free homoepitaxy of GaN-based device heterostructures. © 2006 Elsevier B.V. All rights reserved.

  • 26.
    Hirasaki, Takahide
    et al.
    Tokyo University of Agriculture and Technology, Japan.
    Eriksson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Tu Thieu, Quang
    Tokyo University of Agriculture and Technology, Japan.
    Karlsson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Murakami, Hisashi
    Tokyo University of Agriculture and Technology, Japan.
    Kumagai, Yoshinao
    Tokyo University of Agriculture and Technology, Japan.
    Monemar, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Tokyo University of Agriculture and Technology, Japan.
    Holtz, Per-Olof
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Koukitu, Akinori
    Tokyo University of Agriculture and Technology, Japan.
    Growth of thick and high crystalline quality InGaN layers on GaN (000(1)over-bar) substrate using tri-halide vapor phase epitaxy2016In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 456, 145-150 p.Article in journal (Refereed)
    Abstract [en]

    The growth of thick InGaN layers on free-standing GaN (000 (1) over bar substrates was studied using tri-halide vapor phase epitaxy. It was found that high-indium-content InGaN can be grown under higher InCl3 input partial pressure at higher growth temperature, which allows the fabrication of a high crystalline quality InGaN layer with a smooth surface morphology. Using the growth conditions of high InCl3 input partial pressure and high growth temperature, crack- and droplet-free InGaN layers with a thickness of over 10 mu m and with an indium fraction of 0.05 were successfully grown. Although the surface showed many hillocks, the number of hillocks was reduced upon growth of thicker InGaN layers. Photoluminescence measurements confirm that thick InGaN layers could be successfully grown without degradation of the crystalline quality. (C) 2016 Elsevier B.V. All rights reserved.

  • 27.
    Hogberg, H.
    et al.
    Högberg, H., Department of Inorganic Chemistry, Angstrom Lab., Uppsala Univ., P.O., Uppsala, Sweden.
    Birch, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Johansson, M P
    Jansson, U.
    Department of Inorganic Chemistry, Angstrom Lab., Uppsala Univ., P.O., Uppsala, Sweden.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Strain relaxation of low-temperature deposited epitaxial titanium-carbide films2000In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 219, no 3, 237-244 p.Article in journal (Refereed)
    Abstract [en]

    The lattice misfit strain and relaxation during growth of 60-950 angstroms epitaxial TiC carbide films deposited by co-evaporation of C60 and Ti on MgO(0 0 1) have been studied by reciprocal space mapping (RSM) and transmission electron microscopy (TEM). All the films exhibited a strained layer growth behavior with respect to the substrate. The strain e, ranged from 2.1% for the 60 angstroms film to 0.8% for the 950 angstroms film. Initial misfit strain relaxation was by slip on {1 1 0}<1 0 1¯> and {1 1 1}<1 0 1¯>. After dislocation rearrangement the films predominantly exhibited well-developed misfit dislocations of edge type with line direction <1 0 0> along the interface plane and Burgers vectors 1/2[1 0 1¯] inclined to the interface with MgO.

  • 28.
    Hu, Hanmei
    et al.
    Structure Research Laboratory, Department of Chemistry, University of Science and Technology of China.
    Mo, Maosong
    Structure Research Laboratory, Department of Chemistry, University of Science and Technology of China.
    Yang, Baojun
    Structure Research Laboratory, Department of Chemistry, University of Science and Technology of China.
    Zhang, Xuanjun
    Structure Research Laboratory, Department of Chemistry, University of Science and Technology of China.
    Li, Qiaowei
    Structure Research Laboratory, Department of Chemistry, University of Science and Technology of China.
    Yu, Wechao
    Structure Research Laboratory, Department of Chemistry, University of Science and Technology of China.
    Qian, Yitai
    Structure Research Laboratory, Department of Chemistry, University of Science and Technology of China.
    Solvothermal synthesis of Sb2S3 nanowires on a large scale2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 258, no 1-2, 106-112 p.Article in journal (Refereed)
    Abstract [en]

    Sb2S3 nanowires with high aspect ratios have been successfully prepared on a large scale using SbCl3 and Na2S as starting materials in ethylene glycol at 200°C for 10 h. Field emission scanning electron microscopy images and transmission electron microscopy images show that the nanowires have diameters in the range of 20–100 nm and lengths up to 50 μm. Diffuse reflection spectrum indicates that the as-prepared Sb2S3 nanowires have obvious quantum size effects. The effects of reaction parameters on the growth of nanowires were discussed. A possible mechanism on the formation of the Sb2S3 nanowires was proposed.

  • 29.
    Hussain Ibupoto, Zafar
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Khun, K
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Liu, Xianjie
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    AlSalhi, M S.
    King Saud University, Saudi Arabia .
    Atif, M
    King Saud University, Saudi Arabia .
    Ansari, Anees A:
    King Saud University, Saudi Arabia .
    Willander, Magnus
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Well aligned ZnO nanorods growth on the gold coated glass substrate by aqueous chemical growth method using seed layer of Fe3O4 and Co3O4 nanoparticles2013In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 368, 39-46 p.Article in journal (Refereed)
    Abstract [en]

    In this study, Fe3O4 and Co3O4 nanoparticles were prepared by co-precipitation method and sol-gel method respectively. The synthesised nanoparticles were characterised by X-ray diffraction [XRD] and Raman spectroscopy techniques. The obtained results have shown the nanocrystalline phase of obtained Fe3O4 and Co3O4 nanoparticles. Furthermore, the Fe3O4 and Co3O4 nanoparticles were used as seed layer for the fabrication of well-aligned ZnO nanorods on the gold coated glass substrate by aqueous chemical growth method. Scanning electron microscopy (SEM), high resolution transmission electron microscopy [HRTEM], as well as XRD and energy dispersive X-ray techniques were used for the structural characterisation of synthesised ZnO nanorods. This study has explored highly dense, uniform, well-aligned growth pattern along 0001 direction and good crystal quality of the prepared ZnO nanorods. ZnO nanorods are only composed of Zn and O atoms. Moreover, X-ray photoelectron spectroscopy was used for the chemical analysis of fabricated ZnO nanorods. In addition, the structural characterisation and the chemical composition study and the optical investigation were carried out for the fabricated ZnO nanorods and the photoluminescence [PL] spectrum have shown strong ultraviolet (UV) peak at 381 nm for Fe3O4 nanoparticles seeded ZnO nanorods and the PL spectrum for ZnO nanorods grown with the seed layer of Co3O4 nanoparticles has shown a UV peak at 382 nm. The green emission and orange/red peaks were also observed for ZnO nanorods grown with both the seed layers. This study has indicated the fabrication of well aligned ZnO nanorods using the one inorganic nanomaterial on other inorganic nanomaterial due to their similar chemistry.

  • 30. Ivanov, SV
    et al.
    Shubina, Tatiana
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Jmerik, VN
    Vekshin, VA
    Kop'ev, PS
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Plasma-assisted MBE growth and characterization of InN on sapphire2004In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 269, no 1Article in journal (Refereed)
    Abstract [en]

    We report on a close correlation between the growth conditions of InN/Al2O3 (0 0 0 1) epilayers grown by plasma-assisted molecular beam epitaxy (MBE), their optical properties in the IR range, and the In clustering in the layers. High-spatial resolution techniques, namely micro-cathodoluminesesence, back-scattered electron imaging and energy dispersive X-ray analysis, were used to establish this correlation. The In-rich growth conditions, achieved by increasing either the growth temperature or the effective In/N flux ratio, causes the In clustering in InN, responsible in our samples for the 0.7-0.8 eV luminescence and IR optical absorption. Growth under In/N = 1: 1 conditions slightly shifted to the N-rich side generally produces InN layers without visible In clusters, having an optical absorption edge around 1.4 eV. A possible mechanism of In cluster formation is suggested on the basis of thermodynamic considerations for InN MBE growth. (C) 2004 Elsevier B.V. All rights reserved.

  • 31.
    Ivanov, S.V.
    et al.
    Ioffe Institute of RAS, Politeknicheskaya 26, 194021, St. Petersburg, Russian Federation.
    Toropov, A.A.
    Ioffe Institute of RAS, Politeknicheskaya 26, 194021, St. Petersburg, Russian Federation.
    Shubina, T.V.
    Ioffe Institute of RAS, Politeknicheskaya 26, 194021, St. Petersburg, Russian Federation.
    Lebedev, A.V.
    Ioffe Institute of RAS, Politeknicheskaya 26, 194021, St. Petersburg, Russian Federation.
    Sorokin, S.V.
    Ioffe Institute of RAS, Politeknicheskaya 26, 194021, St. Petersburg, Russian Federation.
    Sitnikova, A.A.
    Ioffe Institute of RAS, Politeknicheskaya 26, 194021, St. Petersburg, Russian Federation.
    Kop'Ev, P.S.
    Ioffe Institute of RAS, Politeknicheskaya 26, 194021, St. Petersburg, Russian Federation.
    Reuscher, G.
    Physikalisches Inst. Univ. Wurzburg, Am Hubland, D-97074, Würzburg, Germany.
    Keim, M.
    Physikalisches Inst. Univ. Wurzburg, Am Hubland, D-97074, Würzburg, Germany.
    Bensing, F.
    Physikalisches Inst. Univ. Wurzburg, Am Hubland, D-97074, Würzburg, Germany.
    Waag, A.
    Physikalisches Inst. Univ. Wurzburg, Am Hubland, D-97074, Würzburg, Germany.
    Landwehr, G.
    Physikalisches Inst. Univ. Wurzburg, Am Hubland, D-97074, Würzburg, Germany.
    Pozina, Galia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Bergman, Peder
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    MBE growth and properties of bulk BeCdSe alloys and digital (BeSe: CdSe)/ZnSe quantum wells2000In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 214, 109-114 p.Article in journal (Refereed)
    Abstract [en]

    We report for the first time on MBE growth, structural and optical properties of single layers, quantum well structures and short-period superlattices based on BexCd1-xSe ternary alloys on GaAs. Both the conventional MBE growth mode and the sub-monolayer digital alloying technique (SDA) have been employed for the fabrication of the structures. Compositional boundaries of an instability region 0.03 < x < 0.38, calculated in a regular solution approximation for the completely coherent system, agree well with available experimental data. A suppression of the phase separation in BeCdSe by elastic stress in the layer, accompanied by a strong reduction of the Cd incorporation coefficient has been found. Ultrathin 2.8 ML BeCdSe SDA QWs with x approx. 0.15 demonstrate about an order of magnitude increase in the PL intensity with respect to the pure CdSe one, probably resulting from an enhanced carrier localization efficiency. Eg as a function of the Be content reveals a strong bowing in optical data, which allows one to consider BeCdSe alloys with compositions nearly lattice-matched to GaAs as potential materials for the active region of blue-green lasers.

  • 32. Jacobson, H.
    et al.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Raback, P.
    Råback, P., Center of Scientific Computing, Box 405, FIN-02101 Espoo, Finland.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Henry, Anne
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Tuomi, T.
    Optoelectronics Laboratory, Helsinki University of Technology, P.O. Box 3000, 02015 TKK, Finland.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Materials Science .
    Lateral enlargement of silicon carbide crystals2004In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 270, no 1-2Article in journal (Refereed)
    Abstract [en]

    A new growth technique for lateral enlargement of silicon carbide crystals is presented and evaluated. The technique is based on PVT growth but modified with respect to temperature gradients and geometry as compared to conventional setup. Simulation of the temperature distribution for lateral growth as well as the growth mechanism is discussed. High-resolution X-ray diffraction and synchrotron white beam X-ray topography have been evaluated concerning structural defects. The results show that this growth technique makes it possible to enlarge seed crystals without threading screw dislocations and micropipes along the 0001 direction, but stacking faults are introduced due to the crystal stacking sequence along the <11¯00> directions. © 2004 Elsevier B.V.

  • 33. Jacobson, H.
    et al.
    Yakimova, Rositsa
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Syväjärvi, Mikael
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Kakanakova-Georgieva, Anelia
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Tuomi, T.
    Janzén, Erik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Structural impact of LPE buffer layer on sublimation grown 4H-SiC epilayers2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 256, no 3-4, 276-282 p.Article in journal (Refereed)
    Abstract [en]

    The objective of this work was to study the effect of a liquid phase epitaxy buffer layer on the development of defects in sublimation grown epitaxial layers of 4H-SiC. The results were analyzed with the aid of optical microscope, scanning electron microscope, high-resolution X-ray diffraction and synchrotron white beam X-ray topography. A pronounced effect of the liquid phase epitaxy buffer layer on formation of dislocations and micropipes is observed in the sublimation epitaxy layers. It has been shown that during sublimation growth of epilayer with a thin liquid phase epitaxy buffer layer (0.1µm) defects may undergo transformation and stacking faults can be formed. Sublimation grown epilayers grown on a thick liquid phase epitaxy buffer layer (1µm) also showed a symmetrical distribution of misfit dislocations along the <112¯0> and [11¯00] directions. © 2003 Elsevier B.V. All rights reserved.

  • 34.
    Ji, W.
    et al.
    ABB Corporate Research, S-721 78 Västerås, Sweden.
    Lofgren, P.M.
    ABB Corporate Research, S-721 78 Västerås, Sweden, Faxén Laboratory, Royal Institute of Technology, S-100 44 Stockholm, Sweden.
    Hallin, Christer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Gu, C.-Y.
    ABB Corporate Research, S-721 78 Västerås, Sweden.
    Zhou, G.
    ABB Corporate Research, S-721 78 Västerås, Sweden.
    Computational modeling of SiC epitaxial growth in a hot wall reactor2000In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 220, no 4, 560-571 p.Article in journal (Refereed)
    Abstract [en]

    A computational model for chemical vapor deposition (CVD) of silicon carbide (SiC) in a hot-wall reactor is developed, where the susceptor is tapered with a rectangular cross-section. The present work focuses on the advection-diffusion-reaction process in the susceptor. The precursors are propane and silane, and the carrier gas is hydrogen with mass fraction higher than 99%. Computed growth rates under different system pressures and precursor concentrations are compared to the experimental data measured on samples grown in the Linkoping CVD reactor. The gas composition distribution in the susceptor and the growth rate profile on the susceptor floor are shown and analyzed. Dependence of the growth rate on precursor concentrations is investigated. It is demonstrated that the growth rate of SiC may either be carbon transport limited or silicon controlled, depending on the input carbon-to-silicon ratio.

  • 35.
    Jokubavicius, Valdas
    et al.
    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.
    Liu, Xinyu
    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.
    Ivanov, Ivan Gueorguiev
    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.
    Growth optimization and applicability of thick on-axis SiC layers using sublimation epitaxy in vacuum2016In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 448, 51-57 p.Article in journal (Refereed)
    Abstract [en]

    We demonstrate growth of thick SiC layers (100–200 µm) on nominally on-axis hexagonal substrates using sublimation epitaxy in vacuum (10−5 mbar) at temperatures varying from 1700 to 1975 °C with growth rates up to 270 µm/h and 70 µm/h for 6H- and 4H–SiC, respectively. The stability of hexagonal polytypes are related to process growth parameters and temperature profile which can be engineered using different thermal insulation materials and adjustment of the induction coil position with respect to the graphite crucible. We show that there exists a range of growth rates for which single-hexagonal polytype free of foreign polytype inclusions can be maintained. Further on, foreign polytypes like 3C–SiC can be stabilized by moving out of the process window. The applicability of on-axis growth is demonstrated by growing a 200 µm thick homoepitaxial 6H–SiC layer co-doped with nitrogen and boron in a range of 1018 cm−3 at a growth rate of about 270 µm/h. Such layers are of interest as a near UV to visible light converters in a monolithic white light emitting diode concept, where subsequent nitride-stack growth benefits from the on-axis orientation of the SiC layer.

    The full text will be freely available from 2018-05-13 11:40
  • 36.
    Kakanakova-Georgieva, Anelia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Persson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Yakimova, Rositsa
    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.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Sublimation epitaxy of AlN on SiC: Growth morphology and structural features2004In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 273, no 1-2, 161-166 p.Article in journal (Refereed)
    Abstract [en]

    In order to study the development of individual AlN crystallites, sublimation epitaxy of AlN was performed on 4H-SiC, off-axis substrates in an inductively heated setup. Growth process variables like temperature, extrinsic nitrogen pressure and time were changed in an attempt to favor the lateral growth of individual AlN crystallites and thus open possibilities to prepare continuous patterns. Scanning and transmission electron microscopy and cathodoluminescence were used to obtain plan-view and cross-sectional images of the grown patterns and to study their morphology and structural features. The growth at 1900°C/200mbar results in AlN pattern consisting of individual single wurzite AlN crystallites with plate-like shape aligned along [1 1̄ 0 0] direction. The only defects these AlN crystallites contain are threading dislocations, some of which are terminated by forming half-loops. Because of the uniform distribution of the crystallites and their high structural perfection, this AlN pattern could represent interest as a template for bulk AlN growth. Alternative growth approaches to AlN crystallite formation are possible resulting in variation of the final AlN pattern structure. From a viewpoint of obtaining continuous patterns, the more favorable growth conditions involve applying of increased extrinsic gas pressure, 700 mbar in our case. © 2004 Elsevier B.V. All rights reserved.

  • 37.
    Kakanakova-Georgieva, Anelia
    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.
    Gueorguiev, G.K.
    Departamento De Fisica Da Universidade, 3004-516 Coimbra, Portugal.
    Linnarsson, M.K.
    Solid State Electronics, Royal Institute of Technology, P.O. Box E229, S-164 40 Kista, Sweden.
    Syväjärvi, Mikael
    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.
    Kinetics of residual doping in 4H-SiC epitaxial layers grown in vacuum2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 240, no 3-4, 501-507 p.Article in journal (Refereed)
    Abstract [en]

    Investigation on residual Al, B, and N co-doping of 4H-SiC epitaxial layers is reported. The layers were produced by sublimation epitaxy in Ta growth cell environment at different growth temperatures and characterized by secondary ion mass spectrometry. The vapor interaction with Ta was considered through calculations of cohesive energies of several Si-, Al-, B-, and N-containing vapor molecules and also of diatomic Ta-X molecules. An analysis of kinetic mechanisms responsible for impurity incorporation is performed. Among residuals, B exhibits a stronger incorporation dependence on temperature and growth at lower temperatures can favor B decrease in the layers. Under the growth conditions in this study (Ta environment and presence of attendant Al and N), B incorporation is assisted by Si2C vapor molecule. Boron tends to occupy carbon sites at higher temperatures, i.e. higher growth rates. © 2002 Elsevier Science B.V. All rights reserved.

  • 38.
    Kakanakova-Gueorgieva, Anelia
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Nilsson, Daniel
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    High-quality AlN layers grown by hot-wall MOCVD at reduced temperatures2012In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 338, no 1, 52-56 p.Article in journal (Refereed)
    Abstract [en]

    We report on a growth of AlN at reduced temperatures of 1100 C and 1200 C in a horizontal-tube hot-wall metalorganic chemical vapor deposition reactor configured for operation at temperatures of up to 15001600 C and using a joint delivery of precursors. We present a simple route - as viewed in the context of the elaborate multilayer growth approaches with pulsed ammonia supply - for the AlN growth process on SiC substrates at the reduced temperature of 1200 C. The established growth conditions in conjunction with the particular in-situ intervening SiC substrate treatment are considered pertinent to the accomplishment of crystalline, relatively thin, ∼700 nm, single AlN layers of high-quality. The feedback is obtained from surface morphology, cathodoluminescence and secondary ion mass spectrometry characterization.

  • 39. Kasic, A.
    et al.
    Gogova, D.
    Larsson, Henrik
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Ivanov, Ivan Gueorguiev
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Monemar, Bo
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials.
    Fehrer, M.
    Härle, V.
    Highly homogeneous bulk-like 2'' GaN grown by HVPE on MOCVD-GaN template2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 275, e387-e393 p.Article in journal (Refereed)
  • 40.
    Khranovskyy, V.
    et al.
    Institute for Problems of Material Science, Krzhyzhanovskyy Str. 3, 03630 Kyiv, Ukraine, Linkoping University, Department of Physics, Chemistry and Biology, SE-58183 Linkoping, Sweden.
    Minikayev, R.
    Institute of Physics, P.A.S., Al. Lotników 32/46, 02-668 Warsaw, Poland.
    Trushkin, S.
    Institute of Physics, P.A.S., Al. Lotników 32/46, 02-668 Warsaw, Poland.
    Lashkarev, G.
    Institute for Problems of Material Science, Krzhyzhanovskyy Str. 3, 03630 Kyiv, Ukraine.
    Lazorenko, V.
    Institute for Problems of Material Science, Krzhyzhanovskyy Str. 3, 03630 Kyiv, Ukraine.
    Grossner, U.
    University of Oslo, Physics Department, Centre for Materials Science and Nanotechnology, N-0316 Oslo, Norway.
    Paszkowicz, W.
    Institute of Physics, P.A.S., Al. Lotników 32/46, 02-668 Warsaw, Poland.
    Suchocki, A.
    Institute of Physics, P.A.S., Al. Lotników 32/46, 02-668 Warsaw, Poland.
    Svensson, B.G.
    University of Oslo, Physics Department, Centre for Materials Science and Nanotechnology, N-0316 Oslo, Norway.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Materials Science . Linköping University, The Institute of Technology.
    Improvement of ZnO thin film properties by application of ZnO buffer layers2007In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 308, no 1, 93-98 p.Article in journal (Refereed)
    Abstract [en]

    The effect of ZnO buffer layers prepared at different temperatures on the structural, optical and morphological properties of the ZnO main layer is reported. ZnO thin films (comprising a buffer and a main layer) were deposited on (0 0 0 1) c-sapphire substrates by PEMOCVD. Two-step growth regimes were applied to realize a homoepitaxial growth on ZnO buffers: low-temperature ZnO buffer layer deposited at Ts=300 °C and the main layer at Ts=500 °C, high-temperature ZnO buffer layer deposited at Ts=500 °C and the main layer at Ts=300 °C. For comparison, a sample grown at high-temperature Ts=500 °C by one-step procedure was used. The low-temperature buffer layer has shown the most beneficial effect on the structural and morphological properties, as expressed by the narrowing of the (0 0 2) diffraction peak (FWHM=0.07°) and crystallite size enlargement. However, the surface roughness of this sample is higher then that of the sample grown by one-step procedure and this needs further considerations. The photoluminescence results seem to support a conclusion that the application of a low-temperature buffer layer among the studied temperature regimes is the most advantageous. © 2007 Elsevier B.V. All rights reserved.

  • 41.
    Kugler, Veronika Mozhdeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Music, Denis
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Andreasson, J.
    Department of Materials Engineering, Luleå University of Technology, Luleå, Sweden.
    Lindback, T.
    Department of Materials Engineering, Luleå University of Technology, Luleå, Sweden.
    Low temperature growth and characterization of (Na,K)NbOx thin films2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 254, no 3-4, 400-404 p.Article in journal (Refereed)
    Abstract [en]

    Thin (Na,K)NbOx perovskite films (NKN) have been deposited on SiO2/Si(0 0 1) substrates at low temperatures, from 350°C to 550°C, by RF magnetron sputtering. The effects of substrate temperature on microstructure, electrical-, and mechanical properties of the NKN films have been studied. X-ray diffraction analysis revealed that films deposited at temperatures in the range of 450–550°C were crystalline, growing as a single phase, with a preferred orientation of (0 0 1). Films deposited at 350°C, were shown to be amorphous. The growth temperature had a strong influence on the electrical properties of the NKN films and the relative dielectric constants of the obtained films were in between 38 and 78. Variations of the mechanical properties of the NKN films were observed for different substrate temperatures: The elastic moduli and the hardness values ranged from 205±26 to 93±29 GPa, and from 12±2 to around 2 GPa, for films deposited at 550°C and 450°C, respectively.

  • 42.
    Kugler, Veronika Mozhdeh
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Söderlind, Fredrik
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Music, Denis
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Helmersson, Ulf
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics.
    Andreasson, J.
    Department of Materials Engineering, Luleå University of Technology, Luleå, Sweden.
    Lindback, T.
    Department of Materials Engineering, Luleå University of Technology, Luleå, Sweden.
    Microstructure/dielectric property relationship of low temperature synthesised (Na,K)NbOx thin films2004In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 262, no 1-4, 322-326 p.Article in journal (Refereed)
    Abstract [en]

    Thin films of (Na,K)NbOx (NKN) were grown by reactive RF magnetron sputtering on polycrystalline Pt80Ir20 substrates, at relatively low growth temperatures between 300°C and 450°C. The results show that the electrical performance and the microstructure of the films are a strong function of the substrate temperature. X-ray diffraction of films grown up to 400°C revealed the formation of only one crystalline NKN-phase with a preferred (0 0 2)-orientation. However, a mixed orientation together with a secondary, paraelectric potassium niobate phase, were observed for NKN films deposited at 450°C. The differences in the microstructure explains the variations in the dielectric constants and losses: The single phase NKN films displayed a dielectric constant and a dielectric loss of 506 and 0.011, respectively, while the films with mixed phases exhibited values of 475 and 0.022, respectively. The possibility of fabricating NKN films with relatively high dielectric properties at low growth temperatures, as demonstrated here, is of high technological importance.

  • 43.
    Lazarev, M.
    et al.
    Ecole Polytech Federal Lausanne, Switzerland.
    Szeszko, J.
    Ecole Polytech Federal Lausanne, Switzerland.
    Rudra, A.
    Ecole Polytech Federal Lausanne, Switzerland.
    Karlsson, K Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Kapon, E.
    Ecole Polytech Federal Lausanne, Switzerland.
    Parabolic tailored-potential quantum-wires grown in inverted pyramids2015In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 414, 196-199 p.Article in journal (Refereed)
    Abstract [en]

    Quasi-one-dimensional AlGaAs quantum wires (QWRs) with parabolic heterostructure profiles along their axis were fabricated using metallorganic vapor phase epitaxy (MOVPE) On patterned (111)B GaAs substrates. Tailoring of the confined electronic states via modification in the parabolic potential profile is demonstrated using model calculations and photoluminescence spectroscopy. These novel nanostructures are useful for studying the optical properties of systems with dimensionality between zero and one. (C) 2014 Elsevier B.V. All rights reserved.

  • 44.
    Leone, Stefano
    et al.
    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.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Nishizawa, S.
    National Institute Adv Ind Science and Technology, Japan .
    Epitaxial growth of SiC with chlorinated precursors on different off-angle substrates2013In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 362, 170-173 p.Article in journal (Refereed)
    Abstract [en]

    This study focuses on the epitaxial growth of silicon carbide (SiC) epitaxial layers, adopting the chloride-based chemical-vapor-deposition (CVD) process, which allows to achieve ten times higher growth rate compared to the standard process based on the mixture of a silicon-containing gas and a hydrocarbon. In order to improve the material quality, substrates with different off-angles were used, since low off-angle substrates result in a reduction of killer defects for specific devices. Different growth mechanisms dominate for different substrate off-cut and an accurate set up of dedicated surface preparation procedures and tuning of growth parameters are needed. This study demonstrates that silicon-rich gas inputs are favorable for lower off-angle (nominally on-axis) substrates, while carbon-rich are beneficial for higher off-angles (usually 8 degrees off-axis for 4H-SiC). Methyltrichlorosilane (MTS) is shown to be the best precursor to achieve the presented results.

  • 45.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    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.
    Kordina, Olle
    Caracal Inc., 611 Eljer way, Ford City, PA, 16226, USA.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Improved morphology for epitaxial growth on 4° off-axis 4H-SiC substrates2009In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 311, no 12, 3265-3272 p.Article in journal (Refereed)
    Abstract [en]

    A process optimization of the growth of SiC epilayers on 4° off-axis 4H-SiC substrates is reported. Process parameters such as growth temperature, C/Si-ratio and temperature ramp up conditions are optimized for the standard non-chlorinated growth in order to grow smooth epilayers without step-bunching and triangular defects. The growth of 6 μm thick n-type doped epitaxial layers on 75 mm diameter wafers is demonstrated as well as that of 20 μm thick layer. The optimized process was then transferred to a chloride-based process and a growth rate 28 μm/h was achieved without morphology degradation. A low growth temperature and a low C/Si ratio are the key parameters to reduce both the step-bunching and the formation of triangular defects.

  • 46.
    Leone, Stefano
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pedersen, Henrik
    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.
    Kordina, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Thick homoepitaxial layers grown on on-axis Si-face 6H- and 4H-SiC substrates with HCl addition2009In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 312, no 1, 24-32 p.Article in journal (Refereed)
    Abstract [en]

    The homoepitaxial growth of 6H- and 4H-SiC on on-axis substrates has been studied in order to demonstrate the growth of thick, mirror-like epitaxial layers without other polytype inclusions and basal plane dislocations. The study was done in a hot wall reactor using standard precursors silane and ethylene with hydrogen chloride (HCl) addition. The main important process parameters were studied, in particular deposition temperature, and precursor ratios such as C/Si, Cl/Si and Si/H2. The addition of chlorine in the precursor mixture was found to be the key parameter to grow layers at high rate with morphology and thickness similar to epilayers deposited on commonly used off-axis substrates. Two different process conditions were found allowing growth of low-doped (in the low 1014 cm−3 range) 100-μm-thick epitaxial layers at a growth rate of 25 μm/h, 8 times higher than what is achieved without HCl addition. A high concentration of SiCl2 in the gas phase obtained by high Cl/Si and Si/C ratios was fundamental to achieve these results.

  • 47.
    Li, K.
    et al.
    National Key Lab of Analog IC, SISC, MII, 14 Huayuan Rd, Nanping, Chongqing 400060, China.
    Zhang, J.
    National Key Lab of Analog IC, SISC, MII, 14 Huayuan Rd, Nanping, Chongqing 400060, China.
    Liu, D.
    National Key Lab of Analog IC, SISC, MII, 14 Huayuan Rd, Nanping, Chongqing 400060, China.
    Yi, Q.
    National Key Lab of Analog IC, SISC, MII, 14 Huayuan Rd, Nanping, Chongqing 400060, China.
    Guo, L.
    National Key Lab of Analog IC, SISC, MII, 14 Huayuan Rd, Nanping, Chongqing 400060, China.
    Xu, S.
    National Key Lab of Analog IC, SISC, MII, 14 Huayuan Rd, Nanping, Chongqing 400060, China.
    Ni, Wei-Xin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics .
    MBE-based SiGe/Si heterojunction multilayer structures2001In: Journal of Crystal Growth, ISSN 0022-0248, Vol. 227-228, 744-748 p.Conference paper (Other academic)
    Abstract [en]

    In this paper, SiGe/Si multilayer heterostructures prepared by molecular beam epitaxy (MBE) are described with the aim of manufacturing SiGe heterojunction bipolar transistors (HBTs). Based on the simulations made by Medici, device structures have been designed and grown. The quality of the MBE layered structures has been characterized by reflection high-energy electron diffraction, X-ray diffraction, secondary ion mass spectrometry and spreading resistance. Furthermore, SiGe-HBTs have been fabricated. Promising DC and RF results of processed HBT devices have been obtained. © 2001 Elsevier Science B.V.

  • 48.
    Li, Xun
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Hemmingsson, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Forsberg, Urban
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Pozina, Galia
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Properties of GaN layers grown on N-face free-standing GaN substrates2015In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 413, 81-85 p.Article in journal (Refereed)
    Abstract [en]

    GaN layers were homoepitaxially grown on N-face free-standing GaN substrates using a hot-wall metalorganic chemical vapor deposition method. By using optimized growth parameters, layers with a smooth morphology were obtained. The crystalline quality of epilayers was studied by a high resolution X-ray diffraction technique and compared to the substrates. Optical properties of the epilayers studied by low temperature time-resolved photoluminescence have shown longer recombination time for donor-bound exciton compared to the substrates. (C) 2014 Elsevier B.V. All rights reserved.

  • 49.
    Lilja, Louise
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Don Booker, Ian
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    ul-Hassan, Jawad
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Janzén, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    Bergman, Peder
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, The Institute of Technology.
    The influence of growth conditions on carrier lifetime in 4H-SiC epilayers2013In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 381, 43-50 p.Article in journal (Refereed)
    Abstract [en]

    4H-SiC homoepitaxial layers have been grown in a horizontal hot-wall CVD (chemical vapor deposition) reactor and the measured carrier lifetimes have been correlated to the CVD growth conditions. Two different generations of reactors were compared, resulting in measured carrier lifetimes in two different orders of magnitude, from a few hundreds of ns to a few ms. The variations in measured carrier lifetime were correlated to deep level concentrations of the Z(1/2) center and the D-1 center, seen by photoluminescence. Decreasing the growth temperature clearly prolonged the carrier life time and showed lower Z(1/2) concentrations, where as lowering the growth rate only showed a small improvement of the carrier lifetime and no obvious tendencyin Z(1/2) defect concentrations, indicating that Z(1/2) is not the only defect limiting the carrier lifetime. Increasing the C/Si ratio resulted in decreasing Z(1/2) concentrations, indicating the carbon vacancy nature of the defect. However, carrier lifetime measurements showed maximum values for a C/Si ratio of 1 but otherwise an increasing tendency for increasing C/Si ratios. The reactor giving higher carrier lifetimes, correspondingly also showed lower Z(1/2) concentrations indicating the lifetime limiting property of Z(1/2). Furthermore, the D-1 defect intensity increased with growth temperature and decreased with increasing C/Si ratio, similar to the Z(1/2) concentration.

  • 50.
    Lorenzzi, J.
    et al.
    Université Claude Bernard Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces 43 Bd du 11 Novembre 1918, Villeurbanne CEDEX 69622, France.
    Zoulis, G.
    Groupe d’Etude des Semiconducteurs, UMR 5650, CNRS and Université Montpellier 2, cc 074-GES, Montpellier CEDEX 5, 34095, France.
    Marinova, M.
    Department of Physics, Aristotle University of Thessaloniki, Thessaloniki GR-54 124, Greece.
    Kim-Hak, O.
    Université Claude Bernard Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces 43 Bd du 11 Novembre 1918, Villeurbanne CEDEX 69622, France.
    Sun, J. W.
    Groupe d’Etude des Semiconducteurs, UMR 5650, CNRS and Université Montpellier 2, cc 074-GES, Montpellier CEDEX 5, 34095, France.
    Jegenyes, N.
    Université Claude Bernard Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces 43 Bd du 11 Novembre 1918, Villeurbanne CEDEX 69622, France.
    Peyre, H.
    Université Claude Bernard Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces 43 Bd du 11 Novembre 1918, Villeurbanne CEDEX 69622, France.
    Cauwet, F.
    Université Claude Bernard Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces 43 Bd du 11 Novembre 1918, Villeurbanne CEDEX 69622, France.
    Chaudouët, P.
    Laboratoire des Matériaux et du Génie Physique, CNRS UMR 5628, Minatec Grenoble-INP, 3 parvis Louis Néel, BP 257, Grenoble CEDEX 01, 38016, France.
    Soueidan, M.
    Université Claude Bernard Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces 43 Bd du 11 Novembre 1918, Villeurbanne CEDEX 69622, France.
    Carole, D.
    Université Claude Bernard Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces 43 Bd du 11 Novembre 1918, Villeurbanne CEDEX 69622, France.
    Camassel, J.
    Groupe d’Etude des Semiconducteurs, UMR 5650, CNRS and Université Montpellier 2, cc 074-GES, Montpellier CEDEX 5, 34095, France.
    Polychroniadis, E. K.
    Department of Physics, Aristotle University of Thessaloniki, Thessaloniki GR-54 124, Greece.
    Ferro, G.
    Université Claude Bernard Lyon 1, CNRS, UMR 5615, Laboratoire des Multimatériaux et Interfaces 43 Bd du 11 Novembre 1918, Villeurbanne CEDEX 69622, France.
    Incorporation of group III, IV and V elements in 3C–SiC(1 1 1) layers grown by the vapour–liquid–solid mechanism2010In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 23, 3443-3450 p.Article in journal (Refereed)
    Abstract [en]

    We report on a comparative investigation of the incorporation of group III, IV and V impurities in 3C–SiC heteroepitaxial layers grown by the vapour–liquid–solid (VLS) mechanism on on-axis α-SiC substrates. To this end, various Si-based melts have been used with addition of Al, Ga, Ge and Sn species. Homoepitaxial α-SiC layers grown using Al-based melts were used for comparison purposed for Al incorporation. Nitrogen incorporation depth profile systematically displays an overshoot at the substrate/epilayer interface for all the layers. Ga and Al incorporations follow the same distribution shape as N whereas this is not the case for the isoelectronic impurities Ge and Sn. This suggests some interaction between Ga/Al and N coming from the high bonding energy between the group III and V elements, which does not exist with Ge and Sn. This is why both incorporate as a cluster. A model of incorporation is proposed taking into account metal-N and metal-C bonding energies together with the solid solubility of the corresponding nitrides.

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