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  • 601.
    Zhou, Yan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Perpendicular spin torque promotes synchronization of magnetic tunnel junction based spin torque oscillators2009Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 94, nr 11, s. 112503-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study how the perpendicular spin transfer torque term (b(j)), present in magnetic tunneling junctions (MTJs), affects the synchronization of serially connected MTJ-based spin torque oscillators (MTJ-STOs). We find that b(j) modifies the intrinsic preferred I-V phase shift in single MTJ-STO in such a way that serially connected MTJ-STOs synchronize much more readily without the need for additional circuitry to change the I-V phase. This result strongly suggests that synchronization of serially connected MTJ-STOs should be significantly more straightforward than the previously attempted serial synchronization of giant magnetoresistance based STOs (GMR-STOs).

  • 602.
    Zhou, Yan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sun, Jonathan Z.
    Micromagnetic study of switching boundary of a spin torque nanodevice2011Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, nr 10, s. 102501-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on a numerical study of the micromagnetic switching process of a nanostructured spin torque device. We show that incoherent spin waves can be excited over a wide range of current and field even at zero temperature. These large amplitude, incoherent, and nonzero k spin wave modes are shown to alter the switching phase boundary from that calculated within a macrospin model. The presence of telegraphic transitions between different spin wave modes may also contribute to the so-called back-hopping phenomenon where the switching probability varies nonmonotonically with increasing bias current.

  • 603.
    Zhu, Ning
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Design, Fabrication and Characterization of Planar Lightwave Circuits Based on Silicon Nanowire Platform2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Optical devices based on Planar Lightwave Circuit (PLC) technology have well been studied due to their inherited advantages from Integrated Circuits (IC), such as: small size, high reliability, mass production and potential integration with microelectronics. Among all the materials, silicon nanowire platform gains more and more interest. The large refractive index difference between core and cladding allows tremendous reduction of the component size. This thesis studies theoretically and experimentally some integrated optical devices based on silicon nanophotonic platform, including echelle grating demultiplexers and photonic crystals.

    Some of the numerical methods are introduced first. Scalar integral diffraction method is efficient for calculating the diffraction efficiency of gratings. Beam propagation method and finite-difference time-domain method are also introduced, for simulating the light propagation along the devices.

    The fabrication technology and characterization methods are described. The fabrication steps involve: plasma assisted film deposition, E-beam lithography, RIE-etching. All these steps are proceeded under cleanroom environment. The characterization is mainly based on two methods: end-fire coupling and vertical grating coupling. The grating coupler is more efficient compared with the butt-coupling between fiber and nanowires, but is worse solution for final packaging.

    Two types of components have been realized and characterized with the above technology. The echelle grating demultiplexer is one of the key components in WDM networks. A method for increasing the diffraction efficiency based on total internal reflection is applied, and a significant improvement of the diffraction efficiency of more than 3dB is achieved. A novel cross-order echelle grating-based triplexer, a bidirectional transceiver for application in the Passive Optical Networks (PON), has been designed and fabricated, which can multi/demultiplex three channels located at 1310nm, 1490nm and 1550nm. Polarization dependence issue of echelle grating demultiplexers has been studied. Two polarization compensation schemes have been proposed, which are for the first time polarization insensitive designs of echelle grating demultiplexers based on silicon nanowire platform.

    Photonic crystal devices are also addressed in the thesis. There has been little research on the photonic crystal cavity based on pillar type. A silicon pillar type photonic crystal cavity has been fabricated with the measured Q value as high as about 104, and with an extremely high sensitivity for the changing of the background material or the effective diameter of the pillars. This kind of structure has the advantage on sensing applications compared to the air-hole type structure.

  • 604.
    Zhu, Ning
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Song, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Cross-Order Echelle Grating Triplexer Based on Amorphous Silicon Nanowire Platform2008Inngår i: 2008 7TH INTERNATIONAL CONFERENCE ON THE OPTICAL INTERNET (COIN), NEW YORK: IEEE , 2008, s. 37-38Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present fabrication and measurement results of an ultracompact silicon-on-insulator-based echelle-grating triplexer, which uses different diffraction orders to cover a large spectral range from 1.3 mu m to 1.5 mu m, with a footprint of 150 mu m x 200 mu m.

  • 605.
    Zhu, Ning
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Song, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Design of a polarization-insensitive echelle grating demultiplexer based on silicon nanophotonic wires2008Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 20, nr 9-12, s. 860-862Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A polarization-insensitive design of an echelle grating (or etched diffraction grating) demultiplexer based on silicon nanowires is proposed in the present letter, by introducing a polarization compensation area in its free propagation region. The polarization-dependent wavelength shift of the present device has been compensated at the whole spectral range. For a design with nine channels and 10-nm channel spacing, when the wavelength shift at the central channel 1550 nm is. completely compensated, the wavelength shifts of the two edge channels are only 0.14 and 0.15 nm, which are acceptable.

  • 606.
    Zhu, Ning
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Song, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Etched diffraction grating demultiplexers based on amorphous silicon nanowire platform2008Inngår i: 2008 Asia Optical Fiber Communication and Optoelectronic Exposition and Conference, AOE 2008, 2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We present some theoretical and experimental results of Etched Diffraction Grating demultiplexer based on amorphous silicon nanowire platform, including issues with polarization sensitivity, diffraction efficiency and an application to triplexer.

  • 607.
    Zhu, Ning
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Song, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES).
    Total internal reflection type echelle grating demultiplexer based on amorphous silicon nanowire platform2008Inngår i: Proceedings of SPIE - The International Society for Optical Engineering, Hangzhou, 2008, Vol. 7134Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper we present measurement results of an ultracompact echelle-grating demultiplexer based on silicon-on-insulator nanowire platform, in which we introduced a total internal reflection design of the grating facets to improve the diffraction efficiency. An average increase of the diffraction efficiency with 3.7dB is observed for the 3 channels compared to a normal design.

  • 608.
    Zhu, Ning
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Song, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    He, Sailing
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Experimental demonstration of a cross-order echelle grating triplexer based on an amorphous silicon nanowire platform2009Inngår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 34, nr 3, s. 383-385Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present the design, fabrication, and characterization of an ultracompact silicon-on-insulator-based echelle grating triplexer. It is based on the cross-order design, which utilizes different diffraction orders to cover a large spectral range from 1.3 to 1.5 mu m with three channels located at 1310, 1490, and 1550 nm and with a footprint of 150 mu m X 130 mu m.

  • 609.
    Zhu, Ning
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wang, Zhechao
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    Wosinski, Lech
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Zhejiang-KTH Joint Research Center of Photonics, JORCEP.
    He, Sailing
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Bragg grating-assisted optical triplexer using two silicon nanowire-based directional couplers2009Inngår i: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, 2009, s. 5377094-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A triplexer based on silicon nanophotonic wire structure consisting of two Bragg grating-assisted directional couplers is proposed. The device has low loss, low crosstalk, and a footprint of only 210 x40 μm, The 1-dB bandwidth for the three channels located at 1310, 1490 and 1550 nm are 110, 20, and 20 nm, respectively.

  • 610. Åhlund, J.
    et al.
    Nilson, K.
    Palmgren, Pål
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Göthelid, E.
    Schiessling, J.
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Mårtensson, N.
    Puglia, C.
    STM investigation of FePc on InSb(001)c8x2Manuskript (Annet vitenskapelig)
  • 611.
    Åkerman, Johan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    DeHerrera, M.
    Slaughter, J. M.
    Dave, R.
    Sun, J. J.
    Martin, J. T.
    Tehrani, S.
    Intrinsic reliability of AlOx-based magnetic tunnel junctions2006Inngår i: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 42, nr 10, s. 2661-2663Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a detailed investigation into the intrinsic tunnel barrier reliability in AlOx-based magnetic tunnel junctions (MTJs) as a function of aluminum thickness and oxidation time. The intrinsic reliability is measured as the ramped breakdown voltage (V-bd) at room temperature for both positive and negative polarity. We find that Vbd generally increases with the resistance-area (RA) product of the MTJ. While this dependence is quite strong at low RA, it gradually weakens for higher RA. At fixed RA, Vbd also depends on the original Al film thickness with better properties for thicker Al. Finally, we observe a polarity dependence of V-bd which changes sign as the MTJ goes from thin Al to thick Al. We attribute the polarity dependence to the different quality of the top and bottom interfaces and conclude that the interface emitting the tunneling electrons primarily governs the barrier reliability.

  • 612.
    Åkerman, Johan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    DeHerrera, M.
    Slaughter, J. M.
    Dave, R.
    Sun, J.
    Tehrani, S.
    Intrinsic reliability of AlOx-based magnetic tunnel junctions2006Konferansepaper (Fagfellevurdert)
  • 613.
    Åkerman, Johan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ström, Valter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Rao, K. V.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Dahlberg, E. Dan
    Separation of exchange anisotropy and magnetocrystalline anisotropy in Co/CoO bilayers by means of ac susceptibility measurements2007Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, nr 14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In Co/CoO bilayers separation of the unidirectional anisotropy energy from crystalline anisotropy is accomplished with the temperature variation of the ac susceptibility from room temperature to 4.2 K. Measurements above the blocking temperature of the CoO layer give a clear measure of crystalline anisotropy in the Co. At 4.2 K 85% of the total anisotropy is from K-ud while the anisotropy of the Co layer only contributes about 15%. The small crystalline anisotropy energy does not account for the large difference between the exchange anisotropy determined by ac susceptibility and hysteresis loops.

  • 614.
    Åkermark, Torbjörn
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Emmoth, Birger
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Bergsåker, Henric
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Laser annealing in combination with mass spectroscopy, a technique to study deuterium on tokamak carbon samples, a tool for detritiation2006Inngår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 359, nr 3, s. 220-226Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study, a method is presented based on mass spectroscopy to measure the a real density of deuterium on a graphite surface exposed to tokamak discharges. The studied sample was cut from a bumper limiter exposed in the TEXTOR tokamak and annealed by a 1 J Excimer laser (KrF). The energy used was 400 mJ cm(-2), which is below the threshold for ablation. 1 J cm(-2). The release of HD and D, was measured by a mass spectroscopy set-up and no other species released from the sample were detected in this experiment. The amount of D released from the sample after 20 laser pulses was measured to 7 x 10(16) D atoms per cm(-2) (for this particular sample) and most of the hydrogen at the surface was released in the first pulse, as checked by nuclear reaction analysis (NRA) techniques, which gave changes of the amount of deuterium before and after laser annealing. The sensitivity in this experiment was 5 x 10(14) atoms per cm(-2) for HD and 5 x 10(13) atoms per cm(-2) for D-2.

  • 615.
    Östling, Mikael
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Lee, Hyung-Seok
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Zetterling, Carl Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Silicon carbide devices and processes - Present status and future perspective2006Inngår i: Proceedings of the International Conference Mixed Design of Integrated Circuits and Systems / [ed] Napieralski, A, 2006, s. 34-42Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Silicon carbide electronic devices are already commercially available in a few application areas such as high voltage rectifiers and emerging rf power amplifiers. Over the past 15 years a very rapid progress of both materials and device quality has been seen and is very encouraging for the near future application market. Prototype devices show amazing improvement each year in all device categories as well as a markedly improved wafer quality. However, materials defect issues are still limiting economically viable production of large area devices with high yield. In this paper a thorough review of progress in SiC device process technology and presents the state-of-the art SiC devices as well as new application areas such as ferroelectric field effect transistors.

10111213 601 - 615 of 615
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