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  • 1. Barcena, L. T.
    et al.
    Shiomi, J.
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Control of oscillatory thermocapillary convection with local heating2006In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 286, no 2, p. 502-511Article in journal (Refereed)
    Abstract [en]

    In this experimental work, a proportional feedback control was applied to attenuate an oscillatory thermocapillary flow in an open cylindrical container (annular configuration) filled with silicon oil with high Prandt1 number (Pr = 14 at 25 degrees C). The control was realized by locally heating the free surface with two point source heaters strategically positioned in different azimuthal positions. The heaters were actuated using the local temperature signals fed back from paired sensors. It is suggested that the shortcoming of the control performance accompanied with the amplification of the harmonic frequency components is due to the coupling of the fundamental and the harmonic modes caused by the local control. A remedy is demonstrated to validate the suggestion, where the coupling can be attenuated by increasing the azimuthal length of the actuation region.

  • 2. Baruah, S.
    et al.
    Dutta, Joydeep
    School of Engineering and Technology, Asian Institute of Technology, Thailand.
    pH-dependent growth of zinc oxide nanorods2009In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 311, no 8, p. 2549-2554Article in journal (Refereed)
    Abstract [en]

    Here we study the effect of pH variation on the dimension and morphology of zinc oxide (ZnO) nanorods grown through hydrothermal process at temperatures less than 100 °C. ZnO nanorods were grown on pre-seeded glass substrates using zinc nitrate hexahydrate as the source of Zn ions and hexamethylenetetramine as the source of hydroxyl ions. The pH of the reaction bath was found to change gradually from 6.4 to 7.3 in 5 h during the growth process. The growth of the ZnO nanorods was observed to be faster, both laterally and longitudinally, when the growth solution was in basic conditions. However, flower petal like ZnO nanostructures were obtained when the growth process was initiated in basic condition (pH 8–12), indicating that initial acidic conditions were required to obtain nanorods with well-defined hexagonal facets. ZnO is known to erode in acidic condition and the final dimension of the nanorods is determined by a competition between crystal growth and etching. ZnO nanorods of different dimensions, both laterally (diameters ranging from 220 nm to 1 μm) and longitudinally (lengths ranging from 1 to 5.6 μm) were successfully synthesized using the same concentration of zinc nitrate and hexamine in the reaction bath and the same growth duration of 5 h simply through appropriate control of the pH of the reactant solution between 6 and 7.3.

  • 3. Baskar, K.
    et al.
    Sundgren, P.
    Douheret, O.
    Landgren, Gunnar.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Surface morphology and localised states of GaInNAs single quantum wells grown by MOVPE2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 248, p. 431-436Article in journal (Refereed)
    Abstract [en]

    GaInNAs/GaAs single quantum wells (QWs) have been grown by metalorganic vapour phase epitaxy (MOVPE). The surface morphology has been studied by atomic force microscopy (AFM). The density of pits observed on the surface of QW structures was found to depend on the growth temperature and dimethylhydrazine (DMHy) flow. Cross-sectional AFM image showed the presence of defects at the interface of GaInNAs/GaAs. The low temperature photoluminescence characteristics of the QWs as a function of growth temperature. DMHy flow and density of surface pits have been discussed. The origin of pit formation is addressed based on the pyrolysis products present during the growth of QWs. The results suggest that higher growth temperature maybe desirable to obtain good quality GaInNAs QWS.

  • 4.
    Bentzen, Andreas
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Menon, Cyril
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Radamson, Henry H.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Mechanisms of diffusion-enhanced thermal stability of Si/Si1-xGex/Si heterostructures grown by chemical vapor deposition2004In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 261, no 1, p. 22-29Article in journal (Refereed)
    Abstract [en]

    The thermal stability of doped Si/Si0.8Ge0.2/Si (n-p-n or p-n-p) structures grown by reduced pressure chemical vapor deposition has been studied in correlation with the dopant in- and out-diffusion, using high-resolution X-ray reciprocal lattice mapping and secondary ion mass spectrometry as the main characterization tools. Initially, by doping the strained Si0.8Ge0.2 layer with reasonable amounts of boron, phosphorus, or arsenic, the thermal stability of the structures is shown to be dramatically increased compared to intrinsic layers. Secondly, the results show that when the dopants are present only in the Si buffer and cap layers, intrinsic Si spacer layers are required to obtain a significant enhancement in the thermal stability. These spacers reduce the interfacial dopant concentration and act as barriers for direct injection of precipitates into the SiGe layers. Finally, p-n-p and n-p-n structures were studied showing a very good thermal stability, due to enhanced out-diffusion of dopants from the SiGe layer upon in-diffusion from the adjacent layers. By employing i-Si spacers, the boron out-diffusion in a n-p-n structure was reduced, giving rise to a degradation of the thermal stability of this structure.

  • 5.
    Bertone, Daniele
    et al.
    Centro Studi e Laboratori Telecomunicazioni.
    Campi, Roberta
    Morello, G.
    Centro Studi e Laboratori Telecomunicazioni.
    Etching of InP-based MQW laser structure in a MOCVD reactor by chlorinated compounds1998In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 195, no 1-4, p. 624-629Article in journal (Refereed)
    Abstract [en]

    Four different chlorinated compounds: 2-chloropropane, dichloromethane, chloroform and carbon tetrachloride have been used to etch InGaAsP/InP MQW laser structures partially masked. Etching experiments were performed in a home-made LP-MOCVD reactor with argon or argon + hydrogen as carrier gas, using phosphine (PH3) or tertiarybutylphosphine (TBP) to prevent thermal decomposition. The etching temperature as well as the chlorinated compound flow were varied to obtain the best trade-off between etch rate and surface morphology. The optimized experimental conditions were applied to etch mesa stripes in a SCH-MQW laser structure, for the first time to our knowledge, followed by lateral InP : Fe regrowth in the same step. Threshold current as low as 4 mA (best value)-6 mA (typical value) and differential quantum efficiency higher than 20% for SI-BM MQW laser have been achieved.

  • 6. Buchholt, K.
    et al.
    Eklund, P.
    Jensen, J.
    Lu, J.
    Ghandi, Reza
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Domeij, Martin
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zetterling, Carl-Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Behan, G.
    Zhang, H.
    Spetz, A. Lloyd
    Hultman, L.
    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, p. 133-137Article 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.

  • 7.
    Campi, Roberta
    et al.
    Agilent Technologies Italia, Turin Technology Centre.
    Codato, Simone
    Agilent Technologies Italia, Turin Technology Centre.
    Soldani, Domenico
    Agilent Technologies Italia, Turin Technology Centre.
    Strain effects on highly strained InAsP/InGaP multi-quantum well structures grown by MOVPE using TBAs and TBP2004In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 265, no 3-4, p. 357-366Article in journal (Refereed)
    Abstract [en]

    The influence of the strain on the material quality of highly strained InAsP/InGaP multi-quantum well (MQW) systems has been studied. The main purpose of our study was to investigate and optimise the epitaxial crystal quality of different QWs structures in order to obtain the best well-barrier system. The strain-compensation technique enabled us to grow InAsP/InGaP-MQWs with strain exceeding ±1% and as many as 20 wells without any material deterioration. The strain-compensated structures have been grown by metalorganic vapor phase epitaxy (MOVPE) using TertiaryButylArsine (TBAs) and TertiaryButylPhosphine (TBP) as group V precursors. Photoluminescence (PL), High-Resolution X-ray Diffraction (HR-XRD), Transmission Electron Microscopy (TEM) have been used to study the MQW structures. Net strain, shear strain and residual strain have been used to evaluate the strain effects on the material quality: strain compensation and abruptness of MQW interfaces are needed in order to obtain high performance material. In addition, in this system, the experimental data suggest that the influence of the strain compensation at the interface between well and barrier, which we define as 'symmetrical' strain, seems to be important in determining the quality of the MQW stacks.

  • 8.
    Codato, Simone
    et al.
    Agilent Technologies Italia, Torino Technology Centre.
    Campi, Roberta
    Agilent Technologies Italia, Torino Technology Centre.
    Rigo, Cesare
    Agilent Technologies Italia, Torino Technology Centre.
    Stano, A.
    Agilent Technologies Italia, Torino Technology Centre.
    Ga assisted in situ etching of AlGaInAs and InGaAsP multi quantum well structures using tertiarybutylchloride2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 282, no 1-2, p. 7-17Article in journal (Refereed)
    Abstract [en]

    In this work, we present Studies on the in situ etching (ISE) technique using tertiarybutylchloride (TBCl) as etchant precursor in a metal organic vapour phase epitaxy (MOVPE) reactor. Experiments were made in PH3 and PH3-free environments at low pressures (50-100 mbar) and in a low-temperature regime (545-600 degrees C). In particular, the combination of standard reactive ion etching (RIE) and ISE for the realization of suitable mesa structures for device applications has been systematically investigated. In our etching experiments InP, InGaAsP and Al-containing multi quantum wells (MQWs) have been used as etching targets. Particular efforts were devoted to the etching of Al-containing structures. For this material, the addition of trimethylgallium (TMGa) during the etching resulted to be of key importance in providing good surface morphology and etching of the MQW structure. The role of Ga species in the etching mechanisms will be discussed. The dependence of surface morphology and mesa shape on etching conditions, in particular, temperature, chlorine concentration, gallium concentration and etching time, will be described.

  • 9. da Silva, A. F.
    et al.
    Dantas, N. S.
    de Almeida, J. S.
    Ahuja, R.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Electronic and optical properties of wurztzie and zinc-blende TlN and AlN2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 281, no 1, p. 151-160Article in journal (Refereed)
    Abstract [en]

    We present calculations of the band structure, density of states and the real and imaginary parts of the dielectric functions in intrinsic TIN and AlN, both for wurtzite and the zinc-blende polytypes. They are based on the local density approximation (LDA) within the density functional theory (DFT), employing the first-principles, full-potential linearized augmented plane wave (FPLAPW) method. We correct the band gap of the AlN by using a quasi-particle method proposed by Bechstedt and Del Sole. The calculated energy gaps, lattice constants and dielectric constants for AlN are in good agreement with available experimental values while for TIN there is no experimental investigation.

  • 10.
    Do-Quang, Minh
    et al.
    KTH, Superseded Departments, Mechanics.
    Amberg, Gustav
    KTH, Superseded Departments, Mechanics.
    Carlberg, Torbjörn
    Three-dimensional modelling of radial segregation due to weak convection2004In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 269, p. 454-463Article in journal (Refereed)
    Abstract [en]

    A comprehensive three-dimensional, time-dependent model of heat, momentum and solute transfer during solidification is carried out to illustrate the influence of weak convection, caused by surface tension forces, on radial dopant segregation occurring in crystal growth under micro-gravity conditions. 3D adaptive finite element method is used in order to simulate the motion and deformation of the solidification interface. The geometry studied is a Bridgman configuration with a partly coated surface. The small slots in the coating gives a free surface in a controlled way, and is varied in order to alter the Marangoni flow. In this study, A comparison is made between the numerical results and the experimental results. A good agreement has been observed for the effective distribution coefficient keff and for the radial segregation [Delta]c’. The radial dopant segregation is affected by weak convection.

  • 11.
    Dou, Maofeng
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Baldissera, Gustavo
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Free exciton absorption in Ga1-xZnxN1-xOx alloys2012In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 350, no 1, p. 17-20Article in journal (Refereed)
    Abstract [en]

    The optical properties of the Ga1-xZnxN1-xOx alloy (x=0.0, 0.25, 0.50, 0.75, and 1.00) are studied by first-principles means, employing the GW method to describe single-particle excitations and the Bethe-Salpeter equation (BSE) to model the two-particle exciton interactions. Intriguingly, we find that the band gaps of the Ga1-xZnxN1-xOx alloy are reduced significantly compared with that of bulk ZnO and GaN. By including the electron-hole interactions within the BSE approach, the imaginary part epsilon(2)(omega) of the dielectric function shows an optical absorption enhancement in the low energy region with the exciton peak below the band gap energy. By comparing the energy difference between the exciton absorption peaks E-ex and the energy gaps E-g, we qualitatively estimate that the strength of excitonic coupling is weaker in the Ga1-xZnxN1-xOx alloy than in both GaN and ZnO. Interestingly, the exciton absorption intensity increases with respect to ZnO content.

  • 12. Fernandez, J. R. L.
    et al.
    Araujo, C. M.
    da Silva, A. F.
    Leite, J. R.
    Sernelius, B. E.
    Tabata, A.
    Abramof, E.
    Chitta, V. A.
    Persson, Clas
    Ahuja, R.
    Pepe, I.
    As, D. J.
    Frey, T.
    Schikora, D.
    Lischka, K.
    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, E-ISSN 1873-5002, Vol. 231, no 3, p. 420-427Article in journal (Refereed)
    Abstract [en]

    The critical impurity concentration N-c of the metal-nonmetal (MNM) transition for the cubic GaN, InN and AIN 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 N-c 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 10K. It presents a metallic character above a certain high impurity concentration identified as N-c. 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.

  • 13.
    Forsberg, Kerstin M.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Engineering.
    Rasmuson, Åke C.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    The influence of hydrofluoric acid and nitric acid on the growth kinetics of iron(III) fluoride trihydrate2015In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 423, p. 16-21Article in journal (Refereed)
    Abstract [en]

    The influence of hydrofluoric acid and nitric acid concentration on the growth rate of beta-FeF3 center dot 3H(2)O crystals has been studied in different hydrofluoric acid (4.7-10.7 mol/(kg H2O)) and nitric acid (2.1-4.6 mol/(kg H2O)) mixtures at 50 degrees C. Seeded desupersaturation experiments were performed and the results were evaluated by considering the chemical speciation using two different speciation programs. The growth rate at 50 degrees C at a supersaturation ratio of 2, expressed in terms of free FeF3, was found to be in the range of (0.4-3.8) x 10(-11) m/s. The growth rate order was found to be two or higher in all experiments. The low growth rate and high growth rate order indicate that the growth rate is governed by the surface integration step. The growth rate was found to be independent of variations in acid concentrations: this is in accordance with the assumption of a surface integration controlled growth rate.

  • 14.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystallization of metal fluoride hydrates from mixed hydrofluoric and nitric acid solutions, Part I: Iron (III) and Chromium (III)2010In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 16-17, p. 2351-2357Article in journal (Refereed)
    Abstract [en]

    Crystallization from hydrofluoric acid/nitric acid solutions supersaturated with Fe(III) and Cr(III) has been investigated. Iron and chromium crystallizes into a solid solution in the form of Cr(Fe)F-3 center dot 3H(2)O, which is isostructural with CrF3 center dot 3H(2)O and alpha-FeF3 center dot 3H(2)O. By seeded isothermal desupersaturation experiments, the growth rate of beta-FeF3 center dot 3H(2)O crystals at 50 degrees C has been studied in hydrofluoric acid and nitric acid solutions containing Cr(III). It is found that the growth rate of beta-FeF3 center dot 3H(2)O is essentially uninfluenced by the presence of 5 g/kg Cr(III). At 50 degrees C and a supersaturation ratio of 2 (c(FeF3)(free)/c(s)(FeF3)(free)), the growth rate is (0.8-2.2) x 10(-11) m/s in 3 mol/(kg solution) HFfree and 3 mol/(kg solution) HNO3.

  • 15.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Rasmuson, Åke
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystallization of metal fluoride hydrates from mixed hydrofluoric and nitric acid solutions, part II: Iron (III) and nickel (II)2010In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 312, no 16-17, p. 2358-2362Article in journal (Refereed)
    Abstract [en]

    Crystallization of nickel fluoride hydrate from mixed pickle acid and the influence of Ni(II) on growth rate of beta-FeF3 center dot 3H(2)O have been studied. Iron and nickel crystallize into an unidentified Fe/Ni fluoride hydrate crystal having the overall mol ratio of Ni, Fe, and F equal to 1:2:8, which is in accordance with the number of fluoride ions needed to balance the positive charges of Ni and Fe. The most probable empirical formula of this material is (FeF3)(2)NiF2(H2O)(6-10). By seeded isothermal desupersaturation experiments, growth rate of beta-FeF3 center dot 3H(2)O crystals at 50 degrees C has been studied in a hydrofluoric acid and nitric acid solution containing Ni(II). It is found that the growth rate of beta-FeF3 center dot 3H(2)O is essentially uninfluenced by the presence of 4 g/kg Ni(II).

  • 16.
    Forsberg, Kerstin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Rasmuson, Åke C
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena.
    Crystal growth kinetics of iron fluoride trihydrate2006In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 296, no 2, p. 213-220Article in journal (Refereed)
    Abstract [en]

    Crystal growth of beta-FeF3 • 3H(2)O has been investigated in mixtures of 3 mol kg(-1) hydrofluoric acid and 3 mol kg(-1) nitric acid at 30, 40 and 50 degrees C. Seeded isothermal desupersaturation experiments have been performed in the range: 1.3 < S < 3.6. Solution samples were analysed for total iron concentration with inductively coupled plasma atomic emission spectroscopy. The true supersaturation driving force was estimated by a proper speciation using the software SSPEC using appropriate stability constants. Growth rate parameters of the BCF surface diffusion growth rate equation and the empirical power-law equation have been estimated by fitting the supersaturation balance equation using a nonlinear optimization procedure. The results show that the growth rate is surface integration controlled. The growth rate at a supersaturation ratio of 2 was found to be 3.5 x 10(-12) m s(-1) at 30 degrees C, 7.4 x 10(-12) m s(-1) at 40 degrees C and 16 x 10(-12) m s(-1) at 50 degrees C. The activation energy of the rate constant of crystal growth was found to be 61 kJ mol(-1). .

  • 17. Forsberg, U.
    et al.
    Danielsson, O.
    Henry, A.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Janzen, E.
    Aluminum doping of epitaxial silicon carbide2003In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 253, no 04-jan, p. 340-350Article 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 50degreesC. The highest atomic concentration of aluminum observed in this study was 3 x 10(17) and 8 x 10(18) cm(-3) in Si and C-face, respectively.

  • 18. Forsberg, U.
    et al.
    Danielsson, O.
    Henry, A.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Janzen, E.
    Nitrogen doping of epitaxial silicon carbide2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 236, no 03-jan, p. 101-112Article 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 75degreesC 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.

  • 19. Gaarder, A.
    et al.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Messmer, E. R.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Dopant distribution in selectively regrown InP: Fe studied by time-resolved photoluminescence2001In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 226, no 4, p. 451-457Article in journal (Refereed)
    Abstract [en]

    We apply time-resolved photoluminescence with 1 mum spatial resolution for the characterization of iron distribution in semi-insulating InP:Fe epitaxial layers regrown by hydride vapor-phase epitaxy around etched mesas. The InP:Fe regrowth was carried out on InP:S mesas etched both along the [110] and [110] crystallographic directions, as well as on InP/InGaAsP in-plane lasers. In all cases, the Fe concentration was found to be close to the target values and showed little variation along the regrown layers.

  • 20. Gautier, S.
    et al.
    Aggerstam, Thomas
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Pinos, Andrea
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Marcinkevicius, Saulius
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Liu, K.
    Shur, M.
    O'Malley, S. M.
    Sirenko, A. A.
    Djebbour, Z.
    Migan-Dubois, A.
    Moudakir, T.
    OLIgazzaden, A.
    AlGaN/AlN multiple quantum wells grown by MOVPE on AlN templates using nitrogen as a carrier gas2008In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 310, no 23, p. 4927-4931Article in journal (Refereed)
    Abstract [en]

    AlxGa1-xN/AlN multiple quantum wells (MQWs) structures were grown by metalorganic vapour phase epitaxy (MOVPE) on pseudo AlN substrates using nitrogen as a carrier gas. Results of X-ray diffraction (XRD) and reciprocal space mapping (RSM) indicated no sign of strain relaxation in the quantum wells with respect to the AlN substrate. The MQW parameters such as thicknesses, growth rates and material compositions were extracted from XRD measurements and demonstrated an agreement with our growth conditions. No indication of parasitic reactions between ammonia and trimethyl-aluminium (TMAI) was detected in our growth process. Optical measurements revealed well-defined photoluminescence peaks at 288 and 280 nm, which are in a good agreement with the transmission experimental data. The piezoelectric field value in the Studied structures was estimated to be 900kV/cm.

  • 21.
    Ghasemi, Masoomeh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Lund University, Sweden.
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Johansson, Jonas
    Thermodynamic assessment and binary nucleation modeling of Sn-seeded InGaAs nanowires2017In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 478, p. 152-158Article in journal (Refereed)
    Abstract [en]

    We have performed a thermodynamic assessment of the As-Ga-In-Sn system based on the CALculation of PHAse Diagram (CALPHAD) method. This system is part of a comprehensive thermodynamic database that we are developing for nanowire materials. Specifically, the As-Ga-In-Sn can be used in modeling the growth of GaAs, InAs, and InxGa(1-x)As nanowires assisted by Sn liquid seeds. In this work, the AsSn binary, the As-Ga-Sn, As-In-Sn, and Ga-In-Sn ternary systems have been thermodynamically assessed using the CALPHAD method. We show the relevant phase diagrams and property diagrams. They all show good agreement with experimental data. Using our optimized description we have modeled the nucleation of InxGa(1-x)As in the zinc blende phase from a Sn-based quaternary liquid alloy using binary nucleation modeling. We have linked the composition of the solid nucleus to the composition of the liquid phase. Eventually, we have predicted the critical size of the nucleus that forms from InAs and GaAs pairs under various conditions. We believe that our modeling can guide future experimental realization of Sn-seeded InxGa(1-x)As nanowires.

  • 22. Jayakumar, O. D.
    et al.
    Gopalakrishnan, I. K.
    Kadam, R. M.
    Vinu, A.
    Asthana, A.
    Rao, K. V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Tyagi, A. K.
    Surfactant-induced enhanced room temperature ferromagnetism in Zn0.96Mn0.03Li0.01O nanoparticles: Prepared by solid-state pyrolitic reaction2007In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 307, no 2, p. 315-320Article in journal (Refereed)
    Abstract [en]

    We report the synthesis of nanoparticles of Zn0.96Mn0.03Li0.01O by a low-temperature solid-state pyrolitic reaction, followed by a surfactant-assisted calcination at 400 degrees C. The X-ray diffraction and transmission electron microscopy analyses showed the formation of impurity free nanocrystals of Mn doped Li co-cloped ZnO with wurtzite structure. XPS data revealed that Mn exists in + 2 oxidation state. DC magnetization measurements as a function of field and temperature showed enhanced room temperature ferromagnetism for the surfactant-treated Zn0:96Mn0.03Li0.01O. FMR signal observed in the EPR spectrum further confirmed its ferromagnetic nature.

  • 23. Kakanakova-Georgieva, A.
    et al.
    Yakimova, R.
    Gueorguiev, G. K.
    Linnarsson, Margareta K.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Syvajarvi, M.
    Janzen, E.
    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 04-mar, p. 501-507Article 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.

  • 24.
    Khartsev, Sergiy
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Kim, Joo-Hyung
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, School of Information and Communication Technology (ICT).
    Integration of colossal magnetoresistors with GaAs2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 284, no 02-jan, p. 1-5Article in journal (Refereed)
    Abstract [en]

    Colossal magnetoresistive (CMR) La0.67Ca0.33MnO3 (LCMO) and La0.67Sr0.33MnO3 (LSMO) films have been grown by pulsed laser deposition technique on GaAs(001) substrates buffered with epitaxial MgO layer. X-ray diffraction revealed strong c-axis out-of-plane orientation and strong in-plane texture of CMR/MgO bilayers on GaAs single crystal. The maximum temperature coefficient of resistivity TCR = 9.0% K-1 at 223 K and 2.0% K-1 at 327 K. and the magnetoresistance Delta rho/rho similar to-7.95% kOe(-1) and -1.47% kOe(-1) have been achieved for LCMO/MgO/GaAs and LSMO/MgO/GaAs heteroepitaxial structures, respectively. Comparison with the test LCMO and LSMO films grown directly onto the bulk MgO(001) single cry tal demonstrates the identity of LSMO/MgO/GaAs and LSMO/MgO films properties whereas the LCMO films grown on MgO buffered GaAs show lower transition temperature T-c = 242 K compared to 253 K in LCMO/MgO.

  • 25. Kitsomboonloha, R.
    et al.
    Baruah, S.
    Myint, M. T. Z.
    Subramanian, V.
    Dutta, Joydeep
    Center of Excellence in Nanotechnology School Of Engineering and Technology, Thailan.
    Selective growth of zinc oxide nanorods on inkjet printed seed patterns2009In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 311, no 8, p. 2352-2358Article in journal (Refereed)
    Abstract [en]

    A method for the selective patterning of zinc oxide (ZnO) nanorods is presented that combines inkjet printing of zinc acetate precursors on a substrate used to form ZnO nanocrystallites that subsequently grow into nanorods in a reaction bath containing zinc acetate and hexamethylamine during a hydrothermal process. A total of 100 μm patterns were formed on glass substrates kept at fixed temperatures by printing dots that can also form lines, arrays and rectangular patterns through the use of a 50 μm printhead. Different concentrations of zinc acetate (0.1-1 M) ink-jetted onto the substrates led to the growth of 100 nm to 1 μm wide ZnO nanorods vertically out of the substrates. The length of the ZnO nanorods could be controlled by the concentration of the precursor solution during the hydrothermal process as well as the duration of growth process.

  • 26.
    Kumar, Mukesh
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Environmental Remediation Materials Unit, National Institute for Materials Science, Japan .
    Baldissera, Gustavo
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Persson, C.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Department of Physics, University of Oslo, Norway .
    David, D. G. F.
    da Silva, M. V. S.
    Freitas, J. A., Jr.
    Tischler, J. G.
    Chubaci, J. F. D.
    Matsuoka, M.
    Ferreira da Silva, A.
    Bulk properties of InN films determined by experiments and theory2014In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 403, p. 124-127Article in journal (Refereed)
    Abstract [en]

    Built properties of InN are determined by combining experimental and theoretical studies. In this work, we produced high quality InN film deposited on GaN templates by a modified ion beam assisted deposition technique confirmed by low temperature photoluminescence and absorption. The density of states, real and imaginary parts of the complex dielectric function and the absorption coefficient are calculated by means of first principles beyond density functional theory. The quasi particle aspect is described in the framework of a quasi particle method (the GW approximation). The calculated band gap energy is similar to 0.8 eV whereas significance in the optical absorption occurs at similar to 1.2 eV, which are consistent with both luminescence and absorption results. The Bethe-Salpeter equation is utilized to model the two particle exciton interactions, revealing a strong excitonic peak just below the absorption edge of InN.

  • 27. LI, G
    et al.
    LINNARSSON, M
    KTH, School of Information and Communication Technology (ICT).
    JAGADISH, C
    ZN DELTA-DOPED GAAS GROWN BY METALORGANIC VAPOR-PHASE EPITAXY1995In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 154, p. 231-239Article in journal (Refereed)
    Abstract [en]

    A number of delta-doping parameters have been changed to study their effects on the hole concentration of Zn delta-doped GaAs grown by metalorganic vapour phase epitaxy using dimethylzinc (DMZn) as a doping precursor. We observed that the hole concentration is dependent on the DMZn partial pressure but independent of the gas now velocity in the reactor. A weak effect of the delta-doping time on the hole concentration infers that the near-equilibrium between the Zn adsorption and desorption can be reached very rapidly. In the regime of the delta-doping temperatures from 600 to 700 degrees C, the Zn desorption predominantly determines the hole concentration, and the Zn desorption activation energy obtained from the Arrhenius-type plot is 2.04 eV. Below 600 degrees C, however, the hole concentration departures from the Arrhenius-type relationship with the reciprocal delta-doping temperature, indicating that some other factors start to influence the Zn delta-doping concentration.

  • 28. Liu, X. Y.
    et al.
    Fälth, J. F.
    Andersson, T. G.
    Holmström, Petter
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Jänes, Peter
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Ekenberg, Ulf
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Structural and optical properties of GaN/AlN multiple quantum wells for intersubband applications2005In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 278, no 1-4, p. 397-401Article in journal (Refereed)
    Abstract [en]

    GaN/AIN multiple quantum well structures of 1, 5 and 20 periods were grown by molecular beam epitaxy (MBE). To investigate structural parameters, symmetrical scan (0002) and reciprocal space mapping in the vicinity of the GaN (10 15) plane were made by X-ray diffraction (XRD). The layer thickness, composition and relaxation were determined and gave good agreement with simulated results. The 20 period multiple quantum well (MQW) sample exhibited an intersubband resonance at 360 meV, which corresponds well to the structure data determined by XRD.

  • 29. Liu, X. Y.
    et al.
    Janes, P.
    Holmstrom, P.
    Aggerstam, T.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Andersson, T. G.
    Growth of GaN and GaN/AlN multiple quantum wells on sapphire, Si and GaN template by molecular beam epitaxy2007In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 300, no 1, p. 79-82Article in journal (Refereed)
    Abstract [en]

    GaN layers of 280 nm thick were grown on sapphire, silicon (1 1 1) and GaN template by plasma assisted molecular beam epitaxy. From atomic force microscopy and high-resolution X-ray diffraction, it was found that GaN grown on sapphire and template gave smooth surface (RMS less then 0.5 nm) and very high crystalline quality (FWHM of (0 0 0 2) scan on sapphire only 48 arcsec). However, GaN growth on Si (1 1 1) provided rough surface and poor crystalline quality. The GaN/AlN multiple quantum well structures were grown on sapphire and template. Intersubband absorption spectra from Fourier transform infrared spectroscopy indicated that layers on GaN templates had better performances than on sapphire substrates.

  • 30. Liu, X.Y
    et al.
    Aggerstam, Thomas
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Jänes, Peter
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Holmström, Petter
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Thylén, Lars
    KTH, School of Information and Communication Technology (ICT), Optics and Photonics.
    Andersson, T. G.
    Investigation of intersubband absorption of GaN/AlN multiple quantum wells grown on different substrates by molecular beam epitaxy2007In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 301, no SPEC. ISS., p. 301-302Article in journal (Refereed)
    Abstract [en]

    Ten period GaN/AlN multiple quantum well (MQW) structures were grown by plasma-assisted molecular beam epitaxy (MBE) on sapphire substrates and metal-organic vapour-phase epitaxy (MOVPE)-grown GaN templates. Samples were investigated by high-resolution X-ray diffraction (HR-XRD) and Fourier transform infrared (FT-IR) spectroscopy. Intersubband (IS) absorbances and FWHM of IS absorption peaks indicated that samples grown on the GaN templates had better characteristics, resulting in a FWHM as low as 93 meV at a peak energy of 700 meV.

  • 31. Liu, Z. L.
    et al.
    Mei, Z. X.
    Zhang, T. C.
    Liu, Y. P.
    Guo, Y.
    Du, X. L.
    Hallén, Anders.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Zhu, J. J.
    Kuznetsov, A. Yu
    Solar-blind 4.55 eV band gap Mg0.55Zn0.45O components fabricated using quasi-homo buffers2009In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 311, no 18, p. 4356-4359Article in journal (Refereed)
    Abstract [en]

    A route for synthesizing high Mg content single-phase wurtzite MgZnO films having band gaps in the solar-blind region is demonstrated by employing molecular beam epitaxy on Al2O3 substrates. Importantly, a low Mg content "quasi-homo" buffer, Mg0.17Zn0.83O, was applied to accommodate a host of structural discrepancies and therefore, avoiding phase separation in a high Mg content film, Mg0.55Zn0.45O, as proved by X-ray diffraction. The Mg fraction in the overgrown single-phase epilayer, Mg0.55Zn0.45O, was confirmed by Rutherford backscattering spectrometry.

  • 32.
    Manavaimaran, Balaji
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA. Anna Univ, Ctr Crystal Growth, Madras 600025, Tamil Nadu, India.
    Ramesh, R.
    Arivazhagan, P.
    Jayasakthi, M.
    Loganathan, R.
    Prabakaran, K.
    Suresh, S.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Baskar, K.
    Influence of initial growth stages on AlN epilayers grown by metal organic chemical vapor deposition2015In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 414, p. 69-75Article in journal (Refereed)
    Abstract [en]

    AIN layers of thickness of about 2 mu m have been grown with AIN nucleation layers (NLs) on (001) sapphire substrates using metal organic chemical vapor deposition. Increasing the AlN-NL deposition temperature from 850 to 1250 degrees C has been found to have significant effect on the surface morphology and the structural quality of the AIN layers. The surface morphology of the AlN-NLs and the AIN layers has been assessed using atomic force microscopy (AFM). The AM images of the AlN-NLs reveal the coalescence pattern of NLs. AM images of the AlN layers and the in-situ reflectance measurement disclose the surface morphology and the growth pattern of the AIN layers, respectively. Smooth surface with macro-steps and terrace features has been achieved for the AIN layer grown on the NL deposited at 950 degrees C. The structural quality of AIN layers has been studied by high resolution X-ray diffraction and Raman spectroscopy. The screw dislocation density from (002) reflection and the average edge dislocation density from (102), (302) and (100) reflections of the AIN layer on NL deposited at 950 degrees C are estimated to be 9 x 10(7) cm(-2) and 4.4 x 10(9) cm(-2), respectively. Lateral correlation length (L) is calculated from the (114) reciprocal space mapping of the AIN layers and correlated with the edge dislocation density of the AIN layers. Raman E-2 (high) phonon mode indicates compressive strain in the AIN layers grown on the NLs deposited at various temperatures. From this work, it has been inferred that the uniform coalescence of the nucleation islands and the complete coverage of AlN-NL determine the surface morphology and the structural quality of the subsequently grown AIN layers.

  • 33. Menon, C.
    et al.
    Bentzen, A.
    Landgren, Gunnar.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Radamson, H. H.
    Defect density in non-selective and selective Si/SiGe structures2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 237, p. 259-263Article in journal (Refereed)
    Abstract [en]

    The epitaxial quality of Si (non-selective or selective epitaxy)/SiGe (non-selective or selective epitaxy) structures applying Si2H2Cl2 or SiH4 as the Si source has been studied. High-resolution reciprocal lattice mapping and X-ray reflectivity measurements have been used to characterise the epitaxial quality and the interfacial defects, respectively. The surface morphology of the structures was studied by atomic force microscopy. It is shown that the generation of defects in non-selective SiGe layers is strongly dependent oil the thickness of the buffer layer. Moreover, the selective growth of a Si buffer layer requires a growth temperature above 770degreesC in order to obtain a smooth layer surface, which is beneficial for the succeeding growth of the SiGe layer. The surface can also be smoothed by an annealing treatment at 900degreesC for 40 s. This annealing step is crucial to remove the interfacial defects in the case of Si/SiGe structures grown with different Si sources.

  • 34. Messmer, E. R.
    et al.
    Lindstrom, T.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    In situ mesa etching and immediate regrowth in a HVPE reactor for buried heterostructure device fabrication2000In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 210, no 4, p. 600-612Article in journal (Refereed)
    Abstract [en]

    Mesa etching in a hydride vapour-phase epitaxy (HVPE) reactor has been studied. Etched depth. underetching and shape of the mesas have been analysed as a function of partial pressures of active gases (HCl, PPI, and InCl) stripe orientation and etching temperature. The experimental results show that the depth and undercut can be etched independently. We propose qualitative mechanisms for etching each of the emerging crystallographic planes ((0 0 1), ( 1 1 0) and {1 1 1}). In situ mesa etching with immediate regrowth was applied to the fabrication of buried heterostructure Fabry-Perot lasers. No surface contamination due to exposure to ambient and low process time are advantages of this technique.

  • 35. Messmer, E. R.
    et al.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Analysis of regrowth evolution around VCSEL type mesas2000In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 219, no 3, p. 185-192Article in journal (Refereed)
    Abstract [en]

    Morphological evolution during hydride vapour phase epitaxial regrowth of InP around vertical cavity surface emitting laser type mesas is studied by varying the input InCl partial pressure. The various emerging planes, indices of which are orientation dependent, have been identified and their growth rates measured. The nature of the emerging planes depends on whether (111)A or (111)B plane is formed initially: further growth relies heavily on how well (111)A or (111)B can collaborate with (001) surface. This is explained in terms of crystallographic structure together with the dangling bond approach. Equal planarisation on the orthogonal directions is feasible at lower InCl partial pressures.

  • 36.
    Metaferia, Wondwosen
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Junesand, Carl
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Gau, Ming-Horng
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Lo, Ikai
    Pozina, Galia
    Hultman, Lars
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Morphological evolution during epitaxial lateral overgrowth of indium phosphide on silicon2011In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 332, no 1, p. 27-33Article in journal (Refereed)
    Abstract [en]

    Epitaxial lateral overgrowth of InP from mesh and line openings on masked InP seed layer on Si(0 0 1) wafer is investigated. Coalescence occurred more rapidly from the mesh openings than from the line openings. Lethargic coalescence in the line openings is attributed to the gradual formation of growth retarding boundary planes in the initial stages of growth. Extended growth leads to complete coalescence in both types of openings. The surface roughness of the coalesced layer is inversely proportional to its thickness. Cathodoluminescence studies on the uncoalesced islands show the emergence of facets with orientation-dependent dopant concentration, but reveal no defects, in contrast to the coalesced regions. The latter are relaxed and their dislocation density deduced from panchromatic cathodoluminescence mapping varies from 6 x 10(6) to 4 x 10(7) cm(-2) depending on the layer thickness; the reduced density at higher thickness indicates partial self annihilation of dislocations. TEM cross-section studies show that most of the threading dislocations originating in the InP seed layer/Si interface are blocked by the mask, but new dislocations are generated. Some of these dislocations are associated with bounding planar defects such as stacking faults, possibly generated during lateral growth across the mask due to unevenness of the mask surface.

  • 37.
    Nagarajan, Mony
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Sudhakar, S.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Material Physics, Semiconductor Materials, HMA.
    Baskar, K.
    Growth of Zn3As2 on GaAs by liquid phase epitaxy and their characterization2011In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 314, no 1, p. 119-122Article in journal (Refereed)
    Abstract [en]

    Zn3As2 epitaxial layers were grown on GaAs (1 0 0) substrates by liquid phase epitaxy (LPE) using Ga as the solvent. Zinc mole fraction in the growth melt was varied from 1.07 x 10(-2) to 6 x 10(-2). X-ray diffraction spectrum exhibits a sharp peak at 43.3 degrees characteristic of Zn3As2 crystalline layer. The peak intensity increases with increase in zinc mole fraction in the growth melt. The compositions of the as-grown Zn3As2 layers were confirmed by energy dispersive X-ray (EDX) analysis. Surface morphology was studied using scanning electron microscopy (SEM) and the thickness of the epilayers was also determined. The Hall measurements at 300 K indicate that Zn3As2 epilayers are unintentionally p-doped. With an increase of zinc mole fraction in the growth melt, carrier concentration increases and carrier mobility decreases. Infrared optical absorption spectroscopy showed a sharp absorption edge at 1.0 eV corresponding to the reported band gap of Zn3As2. (C) 2010 Elsevier B.V. All rights reserved.

  • 38. NORDELL, N
    et al.
    BORGLIND, J
    MOVPE GROWTH OF INP AROUND REACTIVE ION ETCHED MESAS1991In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 114, no 1-2, p. 92-98Article in journal (Refereed)
  • 39. NORDELL, N
    et al.
    BORGLIND, J
    LANDGREN, G
    INFLUENCE OF MOVPE GROWTH-CONDITIONS AND CCL4 ADDITION ON INP CRYSTAL SHAPES1992In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 125, no 3-4, p. 597-611Article in journal (Refereed)
  • 40. NORDELL, N
    et al.
    WILLEN, B
    OLSSON, COA
    WESTERGREN, U
    LANDGREN, G
    GROWTH AND PERFORMANCE OF ALGAAS/GAAS HETEROSTRUCTURE BIPOLAR-TRANSISTORS1991In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 107, no 1-4, p. 909-914Article in journal (Refereed)
  • 41.
    Olsson, Fredrik
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Zhu, Tiankai
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Mion, Gaël
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Large mask area effects in selective area growth2006In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 289, no 1, p. 24-30Article in journal (Refereed)
    Abstract [en]

    In this paper we analyze for the first time selective area growth (SAG) of GaAs by MOVPE on dark field patterns, where the different masking features are dense and at the same time the openings are surrounded by very large mask area (larger than the openings) in all directions. The growth efficiency as a function of filling factors is analyzed using one- and two-dimensional filling factors. That the SAG efficiency cannot be greater than one is found to be true, if a two-dimensional filling factor is employed; this treatment involves three-dimensional transport of the growth rendering species. Finite element method has been used to derive the longitudinal thickness profile in the openings by considering the three-dimensional model. The derived longitudinal thickness profile is found to fit very well with the experimentally measured profile. The diffusion length of the growth rendering species is also extracted from the above profile. For comparison, light field patterns are also treated. Our analysis confirms many previous observations that SAG in the light field patterns can be sufficiently explained by the two-dimensional model.

  • 42.
    Ougazzaden, A.
    et al.
    Georgia Inst Technol, Georgia Tech, Metz, France.
    Rogers, D. J.
    Nanovat SARL, Orsay, France; Univ Technol Troyes, France.
    Teherani, F. Hosseini
    Nanovat SARL, Orsay; Univ Technol Troyes.
    Moudakir, T.
    Univ Metz.
    Gautier, S.
    Univ Metz.
    Aggerstam, Thomas
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Saad, S. Ould
    Georgia Tech, Metz, France.
    Martin, J.
    Univ Metz.
    Djebbour, Z.
    Univ Paris.
    Durand, O.
    Thales Res & Technol France.
    Garry, G.
    Thales Res & Technol France.
    Lusson, A.
    Univ Versailles.
    McGrouther, D.
    Univ Glasgow.
    Chapman, J. N.
    Univ Glasgow.
    Growth of GaN by metal organic vapor phase epitaxy on ZnO-buffered c-sapphire substrates2008In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 310, no 5, p. 944-947Article in journal (Refereed)
    Abstract [en]

    The materials quality and availability of large-area bulk GaN substrates is currently considered a key problem for the continuing development of improved GaN-based devices. Since industrial fabrication of bulk GaN substrates with suitable materials quality has proven very difficult, the opto-GaN industry is currently based on heteroepitaxy using either c-sapphire or 6H SiC substrates. ZnO is promising as a substrate material for GaN because it has the same wurtzite structure and a relatively small lattice mismatch (similar to 1.8%). In this study, we have successfully grown GaN by MOVPE on ZnO-buffered c-sapphire. The growth conditions required to both prevent ZnO degradation and grow monocrystal thin film of GaN have been obtained. SEM, HRXRD and micro-Raman characterizations underlined the presence of the two layers GaN and ZnO with high structural quality.

  • 43. Paskova, T.
    et al.
    Paskov, P. P.
    Goldys, E. M.
    Valcheva, E.
    Darakchieva, V.
    Södervall, U.
    Godlewski, M.
    Zielinski, M.
    Hautakangas, S.
    Saarinen, K.
    Carlström, Carl-Fredrik
    KTH, Superseded Departments, Electronics.
    Wahab, Q.
    Monemar, B.
    Characterization of mass-transport grown GaN by hydride vapour-phase epitaxy2004In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 273, no 1-2, p. 118-128Article in journal (Refereed)
    Abstract [en]

    A comprehensive study of the morphological, optical and microstructural properties of mass-transport (MT) and conventionally grown GaN by hydride vapour-phase epitaxy is presented. Spatially resolved techniques have been utilized to reveal in a comparative way, the characteristics of the material grown either in predominant vertical or lateral growth modes. A strong donor-acceptor pair (DAP) emission is observed from the MT regions with a distinctive intensity contrast between the exciton and DAP emission bands from MT and nontransport regions. Secondary ion mass spectroscopy and imaging were employed to investigate the impurity incorporation into different regions. An increase of residual oxygen and aluminium impurity concentrations was found in the MT areas. In addition, positron annihilation spectroscopy showed a strong signal of Ga vacancy clusters in the MT grown material. The increase of the point defect concentrations of both Ga vacancy and oxygen impurity, most likely forming defect complexes, is related to the enhancement of the DAP emission.

  • 44. Pena, A.
    et al.
    Menaert, B.
    Boulanger, B.
    Laurell, Fredrik
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Canalias, Carlota
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Pasiskevicius, Valdas
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Ortega, L.
    Segonds, P.
    Debray, J.
    Felix, C.
    Bulk PPKTP by crystal growth from high temperature solution2012In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 360, p. 52-55Article in journal (Refereed)
    Abstract [en]

    Periodically-poled ferroelectric crystals show unprecedented efficiency and properties otherwise impossible to obtain. Unfortunately, the sample thickness obtainable today limits their use to low and moderate power application. With the aim of increasing the size of periodically domain-structured crystals with a controlled and regular grating period, we proposed an epitaxial growth process using seeds made of thin plates domain engineered by electric field poling. We demonstrated this process with the ferroelectric crystal KTiOPO4 (KTP) which is one of the most promising candidate materials for that purpose. The poling step requires a sample exhibiting (001) and (00 (1) over bar) faces, so that the growth step has to be performed onto these faces. This constraint is a difficulty to circumvent as these faces are not present in the standard equilibrium morphology. It is then necessary to find the growth conditions enabling to work below the roughening temperature of these faces. By using a high temperature solution method, the so-called "flux method", and by choosing an appropriate chemical composition of the flux solution, we obtained periodically domain-structured KTP layers with thicknesses up to 800 mu m and regular periodicity onto (001) and (00 (1) over bar) faces of the initial PPKTP seeds.

  • 45. Persson, Clas
    et al.
    Ahuja, R.
    da Silva, A. F.
    Johansson, Börje
    First-principle calculations of optical properties of wurtzite AlN and GaN2001In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 231, no 3, p. 407-414Article in journal (Refereed)
    Abstract [en]

    The imaginary part of the dielectric function of wurtzite AIN and GaN has been calculated in the long wavelength limit, using two different first-principle electronic structure methods. The first method is a full-potential linearized augmented plane wave method and the second is a full-potential linear muffin-tin orbital method. From the Kramers-Kronig dispersion relations the real part of the dielectric function has been obtained, taking into account a quasi-particle band-gap correction according to Bechstedt and Del Sole. Absorption due to optical phonons is treated as a delta function in the imaginary part of the dielectric function. Both the longitudinal as well as the transverse components of the dielectric function are presented, showing that the anisotropy is small in these materials. Although we use different correlation potentials in the two methods, the results are similar, We compare our calculated dielectric functions with spectroscopic ellipsometry and reflectance spectra measurements.

  • 46. Persson, Clas
    et al.
    da Silva, A. F.
    Ahuja, R.
    Johansson, Börje
    Effective electronic masses in wurtzite and zinc-blende GaN and AlN2001In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 231, no 3, p. 397-406Article in journal (Refereed)
    Abstract [en]

    The effective electron and hole masses are fundamental quantities of semiconductors, used in numerous analyses of experiments and theoretical investigations. We present calculations of the band structure near the band edges in intrinsic GaN and AIN, both for the wurtzite and the zinc-blende polytypes. We have utilized a full-potential linearized augmented plane wave method within the density functional theory and with two different exchange-correlation potentials. The lattice parameters have been determined by a minimization of the total energy, whereupon the crystal-field splitting, the spin-orbit splitting, and the effective electron and hole masses have been calculated. The calculated effective masses are in good agreement with available experimental values. We show the importance of performing a fully relativistic calculation. For instance, the hole mass in cubic AIN is a very large and negative quantity if the spin-orbit coupling is excluded, whereas the fully relativistic calculation gives a relatively small and positive value.

  • 47.
    Persson, Clas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Ferreira da Silva, A.
    Linear optical response of zinc-blende and wurtzite III-N (III = B, Al, Ga, and In)2007In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 305, no 2, p. 408-413Article in journal (Refereed)
    Abstract [en]

    We present calculated dielectric function epsilon(omega) and linear optical absorption alpha(omega) of the cubic and hexagonal structures of BN, AIN, GaN, and InN, employing an all-electron linearized augmented plane wave method within the local density approximation (LDA) plus quasi-particle (QP) correction. We show that this LDA+QP approach yields accurate high-frequency dielectric constant Moreover, by employing a modelled electron-optical phonon interaction we calculate the static dielectric function epsilon(0).

  • 48. Singer, H. M.
    et al.
    Singer-Loginova, I.
    Bilgram, J. H.
    Amberg, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.
    Morphology diagram of thermal dendritic solidification by means of phase-field models in two and three dimensions2006In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 296, no 1, p. 58-68Article in journal (Refereed)
    Abstract [en]

    We have determined morphology diagrams in two and three dimensions for two different phase-field models [A.A Wheeler, B.T. Murray, R.J. Schaefer, Physica D 66 (1993) 243; A. Karma, W.-J. Rappel, Phys. Rev. E 57 (1998) 4323] for the parameters undercooling and anisotropy of surface tension. The comparison with analytical predictions show a qualitative correspondence, however, the predicted shape of the morphology boundary differs significantly from the shape found in our simulations. The two investigated models show the same quantitative behavior. Our simulations in 3D have shown that the shape of the morphology boundary is qualitatively similar to the one in 2D. However, we find that the border is shifted by an amount of 0.3% on the anisotropy axis. Our simulated 3D structures show a qualitative correspondence to the ones we have found in in situ experiments with xenon.

  • 49. Song, Yuxin
    et al.
    Wang, Shumin
    Roy, Ivy Saha
    Shi, Peixiong
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Lai, Zonghe
    Molecular beam epitaxy growth of InSb1-xBix thin films2013In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 378, p. 323-328Article in journal (Refereed)
    Abstract [en]

    Molecular beam epitaxy growth for InSb1-xBix thin films on (100) GaAs substrates is reported. Successful Bi incorporation for 2% is achieved, and up to 70% of the incorporated Bi atoms are at substitutional sites. The effects of growth parameters on Bi incorporation and surface morphology are studied. Strong In and Ga inter-diffusion induced by Bi incorporation is observed and discussed.

  • 50. Sun, Y. T.
    et al.
    Anand, Srinivasan
    KTH, Superseded Departments, Electronics.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Crystallographic orientation dependence of impurity incorporation during epitaxial lateral overgrowth of InP2002In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 237, p. 1418-1422Article in journal (Refereed)
    Abstract [en]

    Temporally resolved epitaxial lateral overgrowth (ELO) of 12 alternating layers of unintentionally-doped and S-doped InP layers has been conducted in a low-pressure hydride vapour phase epitaxy reactor. The growth was conducted in the openings on a (0 0 1) n-InP substrate and oriented along 30degrees off the [1 1 0] direction. Based on the analysis of the cleaved cross-sections by scanning electron microscopy and scanning capacitance microscopy, an inhomogeneous dopant distribution has been observed within the same ELO layer. This is explained by invoking different bonding configurations exposed to the incorporating dopant atoms in the different emerging planes.

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