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  • 1. Baroni, M. P. M. A.
    et al.
    Conceicao, M. Ventura
    Rosa, R. R.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Arwin, H.
    da Silva, E. F., Jr.
    Roman, L. S.
    Nakamura, O.
    Pepe, I.
    da Silva, A. Ferreira
    Optical and morphological properties of porous diamond-like-carbon films deposited by magnetron sputtering2006In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 352, no 32-35, p. 3734-3738Article in journal (Refereed)
    Abstract [en]

    Porous diamond-like-carbon (PDLC) thin films obtained on silicon substrate by DC low energy magnetron sputtering have been investigated by photoluminescence, transmission and reflection spectroscopy, photoacoustic and spectroscopic ellipsometry. The absorption features observed for these films show similarities with those of porous silicon (PS) as well as in the performed gradient structural pattern classification of the SFM porosity, by means of the computational GPA-flyby environment on PS and PDLC samples. The dielectric function is also calculated for the bulk diamond-like carbon using the full-potential linearized augmented plane wave method within the framework of local density approximation to density functional theory. From the measurement a low real dielectric constant of about 4.5 at 0.8 eV was found whereas the calculated e(1)(0) for the bulk diamond has a value of 5.5.

  • 2. Fokine, Michael
    Underlying mechanisms, applications, and limitations of chemical composition gratings in silica based fibers2004In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 349, p. 98-104Article in journal (Refereed)
    Abstract [en]

    This paper reviews the manufacturing procedure and properties of high-temperature stable chemical composition gratings in silica based optical fibers. Chemical composition gratings are formed by a periodic change in the distribution of dopants by UV exposure and thermal processing, which results in differential diffusion. This is attained through interaction between dopants in the fiber and UV induced hydroxyl groups. The formation of fluorine and oxygen modulated chemical composition gratings is presented and their applications and limitations are discussed.

  • 3. Fokine, Michael
    et al.
    Suzuki, H.
    Goto, T.
    Salto, K.
    Ikushima, A. J.
    High-temperature treatment of hydrogen loaded GeO2: SiO2 glasses for photonic device fabrication2006In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 352, no 07-jun, p. 494-499Article in journal (Refereed)
    Abstract [en]

    High-temperature treatment of hydrogen loaded silica- and germanium doped silica glass, also referred to as OH flooding, has been studied. The removal mechanism of hydroxyl groups in silica glass, during OH flooding, occurs by formation and diffusion of molecular hydrogen, while in germanium doped silica the main diffusion mechanism is attributed to diffusion of molecular water. UV exposure of OH flooded and non-treated germanium doped silica samples, from a ArF laser at 193 nm, show large changes in the asymmetric stretching vibration of Si-O-Si bridges, indicating compaction of the glass network. In addition, the thermal relaxation kinetics of the UV induced compaction are found to be similar for non-treated samples and OH flooded samples.

  • 4. Gottlob, H D B
    et al.
    Lemme, Max C.
    AMO GmbH, AMICA, Aachen, Germany.
    Mollenhauer, T
    Wahlbrink, T
    Efavi, J K
    Kurz, H
    Stefanov, Y
    Haberle, K
    Komaragiri, R
    Ruland, T
    Zaunert, F
    Schwalke, U
    Introduction of crystalline high-k gate dielectrics in a CMOS process2005In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 351, no 21-23, p. 1885-1889Article in journal (Refereed)
    Abstract [en]

    In this work we report on methods to introduce crystalline rare-earth (RE) oxides with high (k > 3.9) dielectric constants (high-k) in a CMOS process flow. Key process steps compatible with crystalline praseodymium oxide (Pr2O3) high-k gate dielectric have been developed and evaluated in metal-oxide-semiconductor (MOS) structures and n-MOS transistors fabricated in an adapted conventional bulk process. From capacitance-voltage measurements a dielectric constant of k = 36 has been calculated. Furthermore an alternative process sequence suitable for the introduction of high-k material into silicon on insulator (SOI) MOS-field-effect-transistors (MOSFET) is presented. The feasibility of this process is shown by realization of n- and p-MOSFETs with standard SiO2 gate dielectric as demonstrator. SiO2 gate dielectric can be replaced by crystalline RE-oxides in the next batch fabrication.

  • 5. Hirose, T.
    et al.
    Fokine, Michael
    Saito, K.
    Ikushima, A. J.
    Waveguide writing by CO2 laser annealing on sputtered silica film2006In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 352, no 07-jun, p. 664-668Article in journal (Refereed)
    Abstract [en]

    We present a novel method for creating refractive-index structures in sputtered silica film using CO2 laser annealing. The silica film was prepared by radio frequency magnetron sputtering on silica substrate. Deposited film with the refractive-index 0.8% higher than that of the silica substrate was realized, with a propagation loss of 0.4 dB/cm. The refractive-index of the silica film could be reduced by CO2 laser annealing, enabling the formation of cladding structure for 2-D waveguide.

  • 6. Hofmeister, H.
    et al.
    Ködderitzsch, P.
    Dutta, Joydeep
    Department of Materials Science, Swiss Fed. Institute of Technology, CH-1015 Lausanne, Switzerland.
    Structure of nanometersized silicon particles prepared by various gas phase processes1998In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 232-234, p. 182-187Article in journal (Refereed)
    Abstract [en]

    We have explored various gas phase processes for the fabrication of nanometersized Si and SiOx particles and measured their structural properties (agglomeration, size, shape, crystallinity, surface roughness and internal structure) by conventional and high resolution electron microscopy. Agglomerated amorphous Si particles, 10-30 nm in size, were prepared by gas phase reactions including cluster growth processes in a low pressure silane plasma. Annealing at 900°C resulted in almost complete crystallisation of nearly spherical particles covered by an amorphous oxide shell. Inert gas arc evaporation of silicon yielded single crystalline, spherical Si particles, 4-16 nm in size, in which no defects were detected. These particles, agglomerated into chains and tangles, are covered entirely by a thin amorphous oxide layer. Thermal evaporation of solid SiO in an inert gas atmosphere produced agglomerated, nearly spherical amorphous SiOx particles, 8-24 nm in size, with considerable surface roughness. Upon annealing at 900°C, the formation of 3-6 nm sized Si crystallites in the interior of these particles was observed.

  • 7. Kavas, H.
    et al.
    Durmus, Z.
    Baykal, A.
    Aslan, A.
    Bozkurt, A.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Synthesis and conductivity evaluation of PVTri-Fe3O4 nanocomposite2010In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 356, no 9-10, p. 484-489Article in journal (Refereed)
    Abstract [en]

    Poly(1-vinyl-1,2,4-triazole) (PVTri)-Fe3O4 nanocomposite with conducting character was synthesized by a wet chemical process. PVTri has been freshly synthesized and coated/adsorbed on magnetite nanoparticles that are synthesized via a sonochemical route. The structure, morphology and electrical properties of the products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermal gravimetric analysis (TGA), scanning electron microscopy (SEM) and Dielectric impedance spectroscopy, respectively. Crystallite size of magnetite was calculated by X-ray line profile fitting as 12 +/- 6 nm. FT-IR and TGA analysis confirm the adsorption of PVTri on magnetite nanoparticles. SEM micrographs revealed that Fe3O4 nanoparticles are slightly aggregated upon PVTri coating. Conductivity and permittivity measurements show the effect of glass transition temperature of polymer par in PVTri-Fe3O4 nanocomposite.

  • 8. Kroll, U.
    et al.
    Meier, J.
    Goetz, M.
    Howling, A.
    Dorier, J. -L
    Dutta, Joydeep
    Shah, A.
    Hollenstein, Ch.
    Influence of higher deposition temperature on a-Si:H material properties, powder formation and light-induced degradation, using the VHF (70 MHz) glow discharge technique1993In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 164-166, p. 59-62Article in journal (Refereed)
  • 9.
    Liao, Guihua
    et al.
    Politecnico di Torino.
    Chen, Qiuping
    Politecnico di Torino.
    Xing, Jianjun
    Politecnico di Torino.
    Gebavi, Hrvoje
    Politecnico di Torino.
    Milanese, Daniel
    Politecnico di Torino.
    Fokine, Michael
    Politecnico di Torino.
    Ferraris, Monica
    Politecnico di Torino.
    Preparation and characterization of new fluorotellurite glasses for photonics application2009In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 355, no 7, p. 447-452Article in journal (Refereed)
    Abstract [en]

    Glasses based on (85 − x)TeO2xZnF2–12PbO–3Nb2O5 (x = 0–40) system have been studied for the first time for fabricating mid-infrared optical fiber lasers. The thermal and optical properties including UV–Vis, Raman as well as FTIR spectra are reported. It is demonstrated that increasing the ZnF2 concentration to 30 mol% significantly increased the thermal stability of the glass. Adding ZnF2 also reduced the hydroxyl (OH) content of the glass resulting in lower optical absorption in the mid-infrared region, which is crucial for infrared laser applications. The glass absorption cut-off edge near 400 nm blue-shifts with increasing ZnF2 addition. Raman spectra show a depolymerization of the glass network with increasing transformation of TeO3+1 to TeO3 structures.

  • 10. Liu, Kun
    et al.
    Yao, Wenhao
    Wang, Dongyang
    Ba, Dechun
    Liu, Hailong
    KTH.
    Gu, Xiaoguang
    Meng, Donghui
    Du, Guangyu
    Xie, Yuanhua
    Ba, Yaoshuai
    A study of intrinsic amorphous silicon thin film deposited on flexible polymer substrates by magnetron sputtering2016In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 449, p. 125-132Article in journal (Refereed)
    Abstract [en]

    Amorphous silicon (a-Si) has gained its popularity in thin film Solar cell fabrication for its high absorption coefficient, high applicability on flexible substrates and practical feasibility for low-cost roll-to-roll mass fabrication. Working as the intrinsic layer, the optical-electrical characteristics of amorphous silicon film is crucial to the cell performance. In this work, the amorphous silicon film has been fabricated on PET substrate by magnetron sputtering method. The main optical-electrical characteristics have been systematically investigated under different fabrication conditions (sputtering power, working pressure, working temperature). The results indicate that the deposition rate increases remarkably from 1.88 to 834 nm/min with the sputtering power increasing from 60 W to 120 W, while the light transmission rate decreases from 86% to 46% in the visible spectrum range (390 nm to 780 nm). Theoretical calculations have been carried out, showing a decreasing deposition rate under an increasing working pressure. A rising temperature provides a higher deposition rate and lower trans-mittance in the certain range. The optimized processing parameters in the fabrication of amorphous silicon thin film are obtained for high photoelectric property on flexible substrates.

  • 11.
    Loiko, Pavel
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Ismail, Nur
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Bradley, Jonathan D. B.
    Götelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Pollnau, Markus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Refractive-index variation with rare-earth incorporation in amorphous Al2O3 thin films2017In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 476, p. 95-99Article in journal (Refereed)
    Abstract [en]

    Rare-earth-doped amorphous aluminum oxide (Al2O3;RE3+) thin films are attractive materials for near-IR amplifiers and lasers that can be integrated with silicon-on-insulator waveguides or deposited onto CMOS-fabricated integrated optical structures. We characterize reactively co-sputtered Al2O3;Tm3+ films on silicon by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy. The refractive index is systematically studied for different Tm3+ concentrations. The resulting increase of refractive index is explained by analyzing the mechanism of incorporating Tm3+ ions into the amorphous Al2O3 network. Sellmeier dispersion formulas are presented.

  • 12.
    Mirnaya, T. A.
    et al.
    The V.Vernadski Institute of General and Inorganic Chemistry of the Ukrainian Academy of Sciences, Kiev, Ukraine.
    Tokmenko, I. I.
    The V.Vernadski Institute of General and Inorganic Chemistry of the Ukrainian Academy of Sciences, Kiev, Ukraine.
    Yaremchuk, G. G.
    The V.Vernadski Institute of General and Inorganic Chemistry of the Ukrainian Academy of Sciences, Kiev, Ukraine.
    Corkery, Robert W.
    YKI, Institute for Surface Chemistry, Stockholm, Sweden.
    Phase diagrams and optical properties of binary liquid crystalline systems of cobalt (II) caprylate with lithium and lead caplylates2011In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 357, no 16-17, p. 3053-3057Article in journal (Refereed)
    Abstract [en]

    The concentration and temperature ranges of liquid crystal and glass formation in binary systems of cobalt (II) caprylate with either lithium or lead caplylates have been studied by differential thermal analysis and optical polarization microscopy. Absorption spectra of Co(II) cations in mesophases and glasses of these binary caprylate systems have been analyzed as a function of temperature and composition to get information on the coordination of Co(II) ions. For the binary system of lead-cobalt caprylate. we found that the Co(II) ions are octahedrally coordinated over the range of temperatures and compositions studied, whereas in the binary lithium-lead caprylate system. the Co(II) ions can exist in both octahedral and tetrahedral coordination depending on composition and temperature. Thermochromic behavior was observed for all compositions studied here, from blue to violet and pink, depending on the composition and temperature of the system studied. An unusual increase of optical density with decreased Co(II) ion concentration has been observed for the Co-Li caprylate binary system up to 50 mol%. An increasingly ionic Co(II) coordination environment as Li ion concentration increases facilitates a concomitant increase in the proportion of more optically dense tetrahedrally coordinated Co(II) ions.

  • 13. Murugesan, S.
    et al.
    Wijayasinghe, A.
    Bergman, Bill
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Ceramics.
    Ion transport studies in CuI-doped silver borovanadate glassy system2008In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 354, no 10-11, p. 1066-1073Article in journal (Refereed)
    Abstract [en]

    In the present report, ionic transport properties and microstructural investigations of superionic materials in a cost-effective glassy system xCuI-(100 - x)[2Ag(2)O-0.7V(2)O(5)-0.3B(2)O(3)], where x = 30, 40, 45, 50 and 60, have been described. The temperature dependent electrical conductivity studies were carried out by ac impedance analysis. The microstructure of the materials studied by SEM indicated the presence of dispersed CuO and AgI micro-crystals in the silver oxysalt glass matrix. High room temperature electrical conductivity of 3.58 x 10(-3) S cm(-1) and low activation energy of 0.24 eV were obtained for the best conducting composition. The ac impedance data were analyzed using impedance and modulus formalisms. These materials show extremely high t(i) value of 0.999 and the ionic conductivity is apparently due to Ag+ ions only. The use of two glass formers helped to form materials with higher T-g, higher thermal stability and better ionic transport properties.

  • 14. Pernice, P.
    et al.
    Paleari, A.
    Ferraris, M.
    Fokine, Michael
    KTH, School of Engineering Sciences (SCI), Applied Physics, Laser Physics.
    Fanelli, E.
    Lorenzi, R.
    Spinolo, G.
    Aronne, A.
    Electric field induced structural modification and second order optical nonlinearity in potassium niobium silicate glass2009In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 355, no 52-54, p. 2578-2582Article in journal (Refereed)
    Abstract [en]

    Second harmonic generation properties have been studied in 23 K2O center dot 27Nb(2)O(5) center dot 50 SiO2 glass subjected to thermal poling. The poling-induced optical nonlinearity. with chi((2)) = 3.8 pm/V, has been related to structural modifications within a surface layer of a few microns on the anode side, as evidenced by means of confocal micro-Raman mapping along the sample thickness. The data indicate that the structural changes result from a charge transport process that causes network modifications in an alkali depleted layer whose thickness is comparable with that of the non-linear region. The Raman data also indicate that in the alkali depleted layer the network polymerization degree increases as a consequence of ion migration. The origin of the nonlinearity and the mechanisms activated by poling are discussed. The mechanism of non-bridging-oxygen to bridging-oxygen bond switching is proposed to explain ion migration and the subsequent structural changes in the glass.

  • 15.
    Rapp, Östen.
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Srinivas, V.
    Nordblad, P.
    Poon, S. J.
    Studies of icosahedral AlPdRe quasicrystals across the metal-insulator transition2004In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 334, p. 356-362Article in journal (Refereed)
    Abstract [en]

    The metal-insulator transition (MIT) in icosahedral AlPdRe quasicrystals is investigated by studying changes in sample properties across the transition. The magnetoresistance (MR) the conductivity sigma(T), and the magnetic susceptibility chi(T) have been studied. The MR results show that an MIT occurs for resistance ratios R [ = rho(4.2 K)/rho(295 K)] of about 20-30. sigma(0 K) is finite, and decreases over four orders of magnitude with increasing R. Besides the MR, the most prominent change in a studied property across the MIT is a change of slope of log sigma(0) vs R. In contrast, no features in the resistivity from 1.5 to 300 K reveals an MIT. New results for chi(T, R) are presented. The diamagnetic Z decreases from the metallic to the insulating side, while on the insulating side chi(T,R) is almost independent of R. Although the MR indicates a disorder driven MIT, there is no support for this picture from the results for Z.

  • 16. Roozmeh, S. E.
    et al.
    Mohseni, Majid
    Tehranchi, M. M.
    Study of magnetoimpedance effect of Co-based amorphous ribbons after current annealing at various kinds of ambient pressure2009In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 355, no 52-54, p. 2653-2656Article in journal (Refereed)
    Abstract [en]

    The physical properties of magnetic amorphous alloys can be improved by using different annealing processes. In this paper, for annealing purposes, different driving currents were flowed through Co-based magnetic amorphous ribbons at different ambient air pressures between 5 x 10(-5) mbar and 10(3) mbar. The magnetoimpedance effect in the annealed samples was studied at a frequency interval between 250 kHz and 10 MHz. Magnetic properties and microstructures of samples were investigated by means of alternative gradient force magnetometers and X-ray diffraction. Regarding the giant magnetoimpedance (GMI) effect, annealing at different ambient pressures with the same current can lead to various responses. For annealing at higher pressures such as in air, higher current is necessary for crystallization of samples which results in the development of greater transverse magnetic anisotropy.

  • 17.
    Srinivas, Vignesh
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rapp, Östen.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Poon, S. J.
    Magnetoresistance of highly resistive AlPdRe quasicrystals2004In: Journal of Non-Crystalline Solids, ISSN 0022-3093, E-ISSN 1873-4812, Vol. 334, p. 427-430Article in journal (Refereed)
    Abstract [en]

    The temperature dependence of the conductivity, sigma(T), and the magnetoresistance (MR), Deltarho(B)/rho, have been studied from below 0.05-300 K for two i-AlPdRe samples on the insulating side of the metal insulator transition. The temperature dependence of resistivity and MR show that there is a definite change in transport mechanism below 20 K. The MR is positive below I K. At intermediate temperatures a negative component develops and at temperatures above similar to40 K the MR is small. The magnetoresistance results are discussed in the framework of Efros-Shklovsksii (ES) variable range hopping. With decreasing temperature the characteristic field regions that describe ES hopping are successively depressed towards smaller magnetic fields and vanish. These results support an insulating ground state in samples with large resistance ratios.

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