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  • 51.
    Chacinski, Marek
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101).
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101).
    Berggren, Jesper
    Yu, X.
    KTH.
    Marcks Von Würtemberg, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Dynamic properties of electrically p-n confined, epitaxially regrown 1.27 μm InGaAs single-mode vertical-cavity surface-emitting lasers2009Inngår i: IET optoelectronics, ISSN 1751-8768, Vol. 3, nr 3, s. 163-167Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dynamic performance including chirp measurements of 1.27 mu m single-mode InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with a large gain-cavity offset is presented. The VCSELs are based on a novel p-n confinement structure with selective area epitaxial regrowth. A resonance frequency of 9.11 GHz, a slope efficiency of 0.25 W/A and an alpha-factor of 5.7 were measured. The modulation bandwidth is limited by electrical parasitics. Eye diagrams at 5 Gb/s with 7 dB extinction ratio and Q-factor around 5 were obtained. The results are compared with the performance of oxide-confined VCSELs with similar active layer and negative gain-cavity detuning.

  • 52.
    Chacinski, Marek
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Stoltz, Bjorn
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC. Hewlett-Packard Laboratories, United States.
    Monolithically Integrated DFB-EAT for Transmission beyond 50 Gb/s2008Inngår i: ICTON MEDITERR WINTER CONFER, New York: IEEE , 2008, s. 211-214Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We demonstrate >= 60 GHz Electro-Absorption-Transceiver (EAT) composed of monolithically integrated Distributed-Feedback laser (DFB) with low drive voltage Electro-Absorption-Modulator. Clear eye-openings at 50 Gb/s for modulation and detection are presented. The device can be used as efficient and compact size transmitter or as detector in direct 80 Gb/s links. Transmission over 7.2 km long fibre with dispersion compensation is achieved.

  • 53.
    Chacinski, Marek
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Stoltz, Björn
    Syntune AB, Kista, Sweden.
    Hammerfeldt, Stefan
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik, Fotonik. KTH, Skolan för informations- och kommunikationsteknik (ICT), Centra, Kista Photonics Research Center, KPRC.
    Monolithically Integrated 100 GHz DFB-TWEAM2009Inngår i: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 7, nr 16, s. 3410-3415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A monolithically integrated distributed feedback (DFB) laser and traveling-wave electro-absorption modulator (TWEAM) with >= 100 GHz -dBe bandwidth suitable for Non-return-to-zero (NRZ) operation with on-off keying (OOK) is presented. The steady-state, small-signal modulation response, microwave reflection, chirp characteristic, and both data operation and transmission were investigated. The DFB-TWEAM was found to be an attractive candidate for future short distance communication in high bitrates systems.

  • 54.
    Chacinski, Marek
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Westergren, Urban
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Schatz, Richard
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    50 Gb/s modulation and/or detection with a travelling-wave electro-absorption transceiver2008Inngår i: 2008 Conference on Optical Fiber Communication/National Fiber Optic Engineers Conference: Vols 1-8, 2008, s. 94-96Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Electro-Absorption-Transceiver (EAT) structures used as efficient Travelling-Wave Electro-Absorption-Modulator (TWEAM) as well as Travelling-Wave-Photo-Detector (TWPD) are investigated. Clear eye-openings at 50Gb/s for modulation and for detection are presented. Transmission over 2.2km and 5km SSMF were achieved.

  • 55.
    Chaciński, Marek
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. TE Connectivity, Bruttovägen 7, Järfälla, Sweden .
    Westergren, U.
    100GHz electro-optical modulator chip2011Inngår i: Opto-Electron. Commun. Conf., OECC, 2011, s. 59-60Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recent development on high speed electro-optical modulator is presented. The performance of 100GHz modulation bandwidth enabling for 100Gbps On-Off-Keying operation is shown.

  • 56. Chamaillard, K.
    et al.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Dainty, C.
    Coherency matrix theory application in statistical studies of light scattering by small rough particles2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A statistical analysis of the Stokes parameters after light scattering by small randomly rough grains shows a linear regression law between Is 2 and Qs 2. A physical interpretation based on the coherence matrix is proposed.

  • 57. Chang, Q.
    et al.
    Li, Qiang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Zhang, Ziyang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Su, Y.
    Micrometer-scale optical up-converter using a resonance-split silicon microring resonator in radio over fiber systems2009Inngår i: OFC: 2009 Conference on Optical Fiber Communication, IEEE , 2009, s. 393-395Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We propose and demonstrate a novel micrometer-scale optical up-converter for converting 1-Gb/s data to 40-GHz milimeter-wave. This scheme utilizes the free-carrier dispersion effect in a resonance-split silicon microring resonator.

  • 58. Chang, Qingjiang
    et al.
    Li, Qiang
    Zhang, Ziyang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Ye, Tong
    Su, Yikai
    A Tunable Broadband Photonic RF Phase Shifter Based on a Silicon Microring Resonator2009Inngår i: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 21, nr 1-4, s. 60-62Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We propose and demonstrate a tunable broadband photonic radio frequency (RF) phase shifter based on a silicon microring resonator. This scheme utilizes the thermal nonlinear effect of the silicon microring to change the electrical phase of the RF signal with a wide tuning range. A prototype of the phase shifter is experimentally demonstrated for a 40-GHz signal with a 0-4.6-rad tuning range.

  • 59.
    Chen, Jiajia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Design, analysis and simultion for optical access and wide-area networks.2009Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Due to the tremendous growth of traffic volume caused by both exponential increase of number of Internet users and continual emergence of new bandwidth demanding applications, high capacity networks are required in order to satisfactorily handle the extremely large amount of traffic. Hence, optical fiber communication is the key technology for the network infrastructure. This thesis addresses design, analysis and simulation of access and core networks targeting important research problems, which need to be tackled for the effective realization of next generation optical networks.

    Among different fiber access architectures, passive optical network (PON) is considered as the most promising alternative for the last mile connection due to its relatively low cost and resource efficiency. The inherent bursty nature of the user generated traffic results in dynamically changing bandwidth demand on per subscriber basis. In addition, access networks are required to support differentiated quality of service and accommodate multiple service providers. To address these problems we proposed three novel scheduling algorithms to efficiently realize dynamic bandwidth allocation in PON, along with guaranteeing both the priority and fairness of the differentiated services among multiple users and/or service providers. Meanwhile, because of the increasing significance of reliable access to network services, an efficient fault management mechanism needs to be provided in PON. In addition, access networks are very cost sensitive and the cost of protection should be kept as low as possible. Therefore, we proposed three novel cost-effective protection architectures keeping in mind that reliability requirement in access networks should be satisfied at the minimal cost.

    Regarding the optical core networks, replacing electronic routers with all-optical switching nodes can offer significant advantages in realizing high capacity networks. Because of the technological limitations for realizing all-optical nodes, the focus is put on the ingenious architecture design. Therefore, we contributed on novel switching node architectures for optical circuit and packet switching networks. Furthermore, we addressed different aspects of routing and wavelength assignment (RWA) problem, which is an important and hard task to be solved in wavelength routed networks. First, we proposed an approach based on the information summary protocol to reduce the large amount of control overhead needed for dissemination of the link state information in the case of adaptive routing. In addition, transparency in optical networks may cause vulnerability to physical layer attacks. To target this critical security related issue, we proposed an RWA solution to minimize the possible reachability of a jamming attack.

    Finally, in order to evaluate our ideas we developed two tailor-made simulators based on discrete event driven system for the detailed studies of PON and switched optical networks. Moreover, the proposed tabu search heuristic for our RWA solution was implemented in C++.

  • 60.
    Chen, Jiajia
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Wosinska, Lena
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101).
    Tacca, Marco
    Fumagalli, Andrea
    Dynamic routing based on information summary-LSA in WDM networks with wavelength conversion2008Inngår i: Proceedings of 2008 10th Anniversary International Conference on Transparent Optical Networks, ICTON, NEW YORK: IEEE , 2008, s. 50-54Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This Study investigates the use of information Summary (IS) applied to the advertised available resources to reduce the amount of link state advertisement (LSA) overhead, which is necessary to achieve distributed dynamic routing in WDM networks,. As illustrated in the Study, if carefully designed, the resulting IS-LSA protocol can significantly contain the size of the advertised data set without excessively affecting the network performance, i.e., the blocking probability caused by routing decisions based on incomplete link state information.

  • 61. Dave, Renu W.
    et al.
    Steiner, G.
    Slaughter, J. M.
    Sun, J. J.
    Craigo, B.
    Pietambaram, S.
    Smith, K.
    Grynkewich, G.
    DeHerrera, M.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Tehrani, S.
    MgO-based tunnel junction material for high-speed toggle magnetic random access memory2006Inngår i: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 42, nr 8, s. 1935-1939Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the first demonstration of a magnetoresistive random access memory (MRAM) circuit incorporating MgO-based magnetic tunnel junction (MTJ) material for higher performance. We compare our results to those of AlOx-based devices, and we discuss the MTJ process optimization and material changes that made the demonstration possible. We present data on key MTJ material attributes for different oxidation processes and free-layer alloys, including resistance distributions, bias dependence, free-layer magnetic properties, interlayer coupling, breakdown voltage, and thermal endurance. A tunneling magnetoresistance (TMR) greater than 230% was achieved with CoFeB free layers and greater than 85% with NiFe free layers. Although the TMR with NiFe is at the low end of our MgO comparison, even this MTJ material enables faster access times, since its TMR is almost double that of a similar structure with an AlOx barrier. Bit-to-bit resistance distributions are somewhat wider for MgO barriers, with sigma about 1.5% compared to about 0.9% for AlOx. The read access time of our 4 Mb toggle MRAM circuit was reduced from 21 ns with AlOx to a circuit-limited 17 ns with MgO.

  • 62.
    Domeij, Martin
    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.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Analysis of the base current and saturation voltage in 4H-SiC power BJTs2007Inngår i: 2007 European Conference On Power Electronics And Applications: Vols 1-10, 2007, s. 2744-2750Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Silicon carbide (SiC) power bipolar junction transistors are interesting competitors to Si IGBTs for 1200 V power electronics applications. Advantages of SiC BJTs are low collector-emitter saturation voltages, little stored charge and high temperature capability. In this work, SiC NPN power BJTs with common emitter current gains of 40 have been fabricated and characterized. Electrical measurements for BJTs with different emitter widths indicate that the current gain is limited by surface recombination. A low value of V-CESAT=0.9 V at J(C)=100 A/cm(2) was obtained for small and large area (3.4 mm(2)) BJTs and correlated with the formation of low-resistive ohmic contacts to the base. Large area BJTs were shown to operate with a current gain of 48 in pulsed mode at a collector current of 12 A corresponding to J(C)=360 A/cm(2).

  • 63.
    Domeij, Martin
    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.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Schöner, Adolf
    High current gain silicon carbide bipolar power transistors2006Inngår i: Proceedings of the 18th International Symposium on Power Semiconductor Devices and ICs, 2006, s. 141-144Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Silicon carbide NPN bipolar junction transistors were fabricated and a current gain exceeding 60 was obtained for a BJT with a breakdown voltage BV(CEO)=1100 V. A reduction of the current gain was observed after contact annealing at 950 degrees C and this was attributed to degradation of the oxide passivation. Device simulations with varying emitter doping resulted in a maximum current gain for an emitter doping around 1(.)10(19) cm(-3). Resistive turn-off measurements were performed and a minimum collector-emitter voltage (V(CE)) rise-time of 40 ns was found. The VCE rise-time showed a clear dependence on the on-state base current thus indicating a significant stored charge.

  • 64.
    Dong, Lin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hu, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. Zhejiang University, China.
    Ye, Fei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. Helsinki University of Technology, Finland.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Influence of nanoparticles concentration on fluorescence quenching in gold/rhodamine 6G nanoassemblies2009Inngår i: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, Optical Society of America, 2009, s. 5377045-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fluorescence enhancement of dye solution doped with gold nanoparticles is a well-known effect. However, depending on size and concentration, nanoparticles can also deteriorate dye lasing properties due to increased quenching of the excited molecules. Here we report experimental results on such dependence of fluorescence degradation on the nanoparticle concentration.

  • 65.
    Dong, Lin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Pinos, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sugunan, Abhilash
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Popov, Sergei
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP. Helsinki University of Technology, Finland.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Measurement of radiative lifetime in CdSe/CdS core/shell structured quantum dots2009Inngår i: 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, 2009, s. 5377385-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Radiative lifetime of chemically synthesized colloidal CdSe/CdS core/shell quantum dots is measured. Influence of the core size on the electron-hole pair separation is analyzed. A long radiative lifetime and the existence of electron-hole pair separation suggest high potential of these dots as gain material to achieve lasing under continuous-wave excitation.

  • 66. Dumas, Randy K.
    et al.
    Fang, Yeyu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Kirby, B. J.
    Zha, Chaolin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Bonanni, Valentina
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Nogues, Josep
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Probing vertically graded anisotropy in FePtCu films2011Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 84, nr 5, s. 054434-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Field-dependent polarized neutron reflectivity (PNR) and magnetometry are employed to study the magnetic properties of compositionally uniform and graded FePtCu films as a function of annealing temperature (T(A)). The PNR results are able to directly probe the compositional and anisotropy variations through the film thickness. Further details about how the reversal mechanisms evolve are then elucidated by using a first-order reversal curve technique. The reversal of the graded sample annealed at 300 degrees C occurs by an initial rapid switching of the dominant soft A1 phase toward the surface of the film, followed by the gradual reversal of the residual hard phase components toward the bottom. This indicates that the anisotropy gradient is not well established at this low T(A). A fundamentally different mechanism is found after annealing at 400 degrees C, where the rapid switching of the entire film is preceded by a gradual reversal of the soft layers. This suggests that the anisotropy gradient has become better established through the film thickness. The field-dependent PNR measurements confirm the existence of an anisotropy gradient, where the lower (higher) anisotropy portions are now toward the bottom (top) of the film because of the Cu compositional gradient. However, after annealing at 500 degrees C, a single rapid reversal is found, indicating the formation of a uniform hard film. In this case, PNR demonstrates a more uniform magnetic depth profile that is consistent with a uniform reference sample, suggesting significant interdiffusion of the Cu is degrading the compositional and induced anisotropy gradient at this elevated T(A).

  • 67.
    Dzibrou, Dzmitry
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Complex Oxide Photonic Crystals2009Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Microphotonics has been offering a body of ideas to prospective applicationsin optics. Among those, the concept of photonic integrated circuits (PIC’s) has recently spurred a substantial excitement into the scientific community. Relisation of the PIC’s becomes feasible as the size shrinkage of the optical elements is accomplished. The elements based on photonic crystals (PCs) represent promising candidacy for manufacture of PIC’s. This thesis is devoted to tailoring of optical properties and advanced modelling of two types of photonic crystals: (Bi3Fe5O12/Sm3Ga5O12)m and (TiO2/Er2O3)m potentially applicable in the role optical isolators and optical amplifiers, respectively. Deposition conditions of titanium dioxide were first investigated to maximise refractive index and minimise absorption as well as surface roughness of titania films. It was done employing three routines: deposition at elevated substrate temperatures, regular annealing in thermodynamically equilibrium conditions and rapid thermal annealing (RTA). RTA at 500 oC was shown to provide the best optical performance giving a refractive index of 2.53, an absorption coefficient of 404 cm−1 and a root-mean-square surface roughness of 0.6 nm. Advanced modelling of transmittance and Faraday rotation for the PCs (Bi3Fe5O12/Sm3Ga5O12)5 and (TiO2/Er2O3)6 was done using the 4 × 4 matrix formalism of Višňovský. The simulations for the constituent materials in the forms of single films were performed using the Swanepoel and Višňovský formulae. This enabled generation of the dispersion relations for diagonal and off-diagonal elements of the permittivity tensors relating to the materials. These dispersion relations were utilised to produce dispersion relations for complex refractive indices of the materials. Integration of the complex refractive indices into the 4 × 4 matrix formalism allowed computation of transmittance and Faraday rotation of the PCs. The simulation results were found to be in a good agreement with the experimental ones proving such a simulation approach is an excellent means of engineering PCs.

  • 68.
    Dzibrou, Dzmitry
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Grishin, Alexander
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Fitting transmission and Faraday rotation spectra of Bi3Fe5O12/Sm3Ga5O12 (m) magneto-optical photonic crystals2009Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, nr 4, s. 043901-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A consistent microscopic approach is developed to simulate the transmittance and Faraday rotation in all-garnet heteroepitaxial magneto-optical photonic crystals (MOPCs). To compare the experimental and simulation results, [Bi3Fe5O12/Sm3Ga5O12](m) (BIG/SGG) MOPC designed to operate at a telecommunication wavelength lambda(res)=980 nm was chosen. It was composed of [BIG/SGG](5) and [SGG/BIG](5) distributed Bragg reflectors with a microcavity layer of BIG in between. The dispersion relations of the diagonal and off-diagonal elements of the permittivity tensor (epsilon) over cap for BIG in the electric dipole approximation were obtained from the simulation of the transmittance and Faraday rotation for a reference single layer BIG film. Revealed dispersion relations were then combined with the 4 x 4 matrix formalism for magnetic superlattices to compute transmission and Faraday rotation spectra of the MOPC. The results of numerical simulations were found to be in good agreement with the experimental ones.

  • 69.
    Dzibrou, Dzmitry
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Grishin, Alexander
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Kawasaki, H.
    Pulsed Laser Deposited TiO2Films: Tailoring optical properties2008Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 516, nr 23, s. 8697-8701Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    TiO2 amorphous films have been pulsed laser deposited onto glass substrates. Film characterization by X-ray diffraction, atomic force microscopy and transmission spectroscopy was performed with the aim of extracting the information on the film crystalline structure, surface roughness and optical properties. Three methods for improving film optical performance have been employed, namely deposition at elevated temperatures, post-annealing in thermodynamically equilibrium conditions and rapid thermal annealing (RTA). The best characteristics were achieved in the case of the film subjected to RTA at 500 °C: refractive index n = 2.53, absorption coefficient α = 404 cm- 1 at λ = 550 nm and rms surface roughness as low as 0.6 nm. The results obtained were found to be one of the best published so far.

  • 70.
    Dzibrou, Dzmitry
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Grishin, Alexander
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Kawasaki, Hiroharu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Suda, Y.
    Pankov, V. V.
    Tailoring optical properties of pulsed laser deposited TiO2 films2008Inngår i: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY / [ed] Johansson LSO; Andersen JN; Gothelid M; Helmersson U; Montelius L; Rubel M; Setina J; Wernersson LE, BRISTOL, ENGLAND: IOP PUBLISHING LTD , 2008, nr 100, s. 082035-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The paper is dedicated to the investigation into optical properties of TiO2 thin films pulsed laser deposited at the temperature as low as 150 degrees C and subjected to the following heat treatment. Properties of obtained nanocrystalline films were compared to polycrystalline TiO2 films grown at elevated temperatures. The highest transmission and the best morphology in polycrystalline films have been obtained at the growth temperature of 300 degrees C. The two methods of post-annealing of amorphous films were employed: annealing at thermodynamically equilibrium conditions and rapid thermal annealing (RTA). RTA at 500 degrees C enables achievement of the best optical performance: smooth surface and high films transparency.

  • 71.
    Elfström, Niklas
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Eriksson Karlström, Amelie
    KTH, Skolan för bioteknologi (BIO).
    Linnros, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Silicon Nanoribbons for Electrical Detection of Biomolecules2008Inngår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 8, nr 3, s. 945-949Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Direct electrical detection of biomolecules at high sensitivity hat recently been demonstrated using semiconductor nanowires. Here we demonstrate that semiconductor nanoribbons, in this case, a thin sheet of silicon on an oxidized silicon substrate, can approach the same sensitivity extending below the picomolar concentration regime in the biotin/streptavidin case. This corresponds to less than similar to 20 analyte molecules bound to receptors on the nanoribbon surface. The micrometer-size lateral dimensions of the nanoribbon enable optical lithography to be used, resulting in a simple and high-yield fabrication process. Electrical characterization of the nanoribbons is complemented by computer simulations showing enhanced sensitivity for thin ribbons. Finally, we demonstrate that the device can be operated both in inversion as well as in accumulation mode and the measured differences in detection sensitivity are explained in terms of the distance between the channel and the receptor coated surface with respect to the Debye screening length. The nanoribbon approach opens up for large scale CMOS fabrication of highly sensitive biomolecule sensor chips for potential use in medicine and biotechnology.

  • 72.
    Elfström, Niklas
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Juhasz, Robert
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Sychugov, Ilya
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Engfeldt, Torun
    KTH, Skolan för bioteknologi (BIO).
    Eriksson Karlström, Amelie
    KTH, Skolan för bioteknologi (BIO).
    Linnros, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Surface Charge Sensitivity of Silicon Nanowires: Size Dependence2007Inngår i: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 7, nr 9, s. 2608-2612Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Silicon nanowires of different widths were fabricated in silicon on insulator (SOI) material using conventional process technology combined with electron-beam lithography. The aim was to analyze the size dependence of the sensitivity of such nanowires for biomolecule detection and for other sensor applications. Results from electrical characterization of the nanowires show a threshold voltage increasing with decreasing width. When immersed in an acidic buffer solution, smaller nanowires exhibit large conductance changes while larger wires remain unaffected. This behavior is also reflected in detected threshold shifts between buffer solutions of different pH, and we find that nanowires of width > 150 nm are virtually insensitive to the buffer pH. The increased sensitivity for smaller sizes is ascribed to the larger surface/volume ratio for smaller wires exposing the channel to a more effective control by the local environment, similar to a surrounded gate transistor structure. Computer simulations confirm this behavior and show that sensing can be extended even down to the single charge level.

  • 73.
    Elfström, Niklas
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Linnros, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Avalanche breakdown in surface modified silicon nanowires2007Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 91, nr 10, s. 103502-1-103502-3Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electrical conductance of semiconductor nanowires can be changed by charges present on the nanowire surface. At high surface charge density, however, the nanowire channel may be quenched leading to a large shift in the I-DS-V-DS characteristics. In this letter, the authors demonstrate that this shift in V-DS is related to an avalanche effect in the nanowire. Silicon nanowires were fabricated in a top-down approach and the nanowire surface charge density was modified through buffer solutions of different pH values. Computer simulations using representative surface charge and interface charge densities clearly reproduce the data and unambiguously demonstrate the avalanche effect.

  • 74. El-Kallassi, P.
    et al.
    Ferrini, R.
    Zuppiroli, L.
    Le Thomas, N.
    Houdré, R.
    Berrier, Audrey
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Talneau, A.
    Optical and local tuning of planar photonic crystals infiltrated with organic molecules2007Inngår i: Conference on Lasers and Electro-Optics, 2007, CLEO 2007, 2007, s. 1375-1376Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We report on the optical tuning of InP-based planar photonic crystals (PhCs) infiltrated with a photoresponsive liquid crystal system. Preliminary results on the local tuning of PhC devices are also presented.

  • 75. El-Kallassi, P.
    et al.
    Ferrini, R.
    Zuppiroli, L.
    Le Thomas, N.
    Houdré, R.
    Berrier, Audrey
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Talneau, A.
    Optical and local tuning of planar photonic crystals infiltrated with organic molecules2007Inngår i: Lasers and Electro-Optics, 2007 European Conference on and the International Quantum Electronics Conference, 2007, s. 4387041-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We report on the optical tuning of InP-based planar photonic crystals infiltrated with a photoresponsive liquid crystal system. Preliminary results on the local tuning of infiltrated structures are also presented.

  • 76. El-Kallassi, Pascale
    et al.
    Ferrini, Rolando
    Zuppiroli, Libero
    Le Thomas, Nicolas
    Houdré, Romuald
    Berrier, Audrey
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Talneau, Anne
    Optical tuning of planar photonic crystals infiltrated with organic molecules2007Inngår i: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 24, nr 9, s. 2165-2171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The optical tuning of InP-based planar photonic crystals (PhCs) infiltrated with a photoresponsive liquid crystal system is presented. Photoinduced phase transitions of a liquid crystal blend doped with azobenzene molecules are used to tune the optical response of PhC cavities. This process is found to be reversible and stable. Several tuning conditions are analyzed in terms of the blend phase diagram.

  • 77. Engel, B. N.
    et al.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Butcher, B.
    Dave, R. W.
    DeHerrera, M.
    Durlam, M.
    Grynkewich, G.
    Janesky, J.
    Pietambaram, S. V.
    Rizzo, N. D.
    Slaughter, J. M.
    Smith, K.
    Sun, J. J.
    Tehrani, S.
    A 4-mb toggle MRAM based on a novel bit and switching method2005Inngår i: IEEE transactions on magnetics, ISSN 0018-9464, E-ISSN 1941-0069, Vol. 41, nr 1, s. 132-136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    4-Mb magnetoresistive random access memory (MRAM) with a novel magnetic bit cell and toggle switching mode is presented. The circuit was designed in a five level metal, 0.18-mum complementary metal-oxide-semiconductor process with a bit cell size of 1.55 mum(2). The new bit cell uses a balanced synthetic antiferromagnetic free layer and a phased write pulse sequence to provide robust switching performance with immunity from half-select disturbs. This switching mode greatly improves the operational performance of the MRAM as compared to conventional MRAM. A detailed description of this 4-Mb toggle MRAM is presented.

  • 78.
    Eriksson, K. G. Peter
    et al.
    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.
    Lee, Hyung-Seok
    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.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    A Simple and Reliable Electrical Method for Measuring the Junction Temperature and Thermal Resistance of 4H-SiC Power Bipolar Junction Transistors2009Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 600-603, s. 1171-1174Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To determine the maximum allowed power dissipation in a power transistor, it is important to determine the relationship between junction temperature and power dissipation. This work presents a new method for measuring the junction temperature in a SiC bipolar junction transistor (BJT) that is self-heated during DC forward conduction. The method also enables extraction of the thermal resistance between junction and ambient by measurements of the junction temperature as function of DC power dissipation. The basic principle of the method is to determine the temperature dependent IN characteristics of the transistor under pulsed conditions with negligible self-heating, and compare these results with DC measurements with self-heating. Consistent results were obtained from two independent temperature measurements using the temperature dependence of the current gain, and the temperature dependence of the base-emitter IN characteristics, respectively.

  • 79.
    Espinosa-Arronte, Beatriz
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Andersson, Magnus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik.
    Scaling of vortex-liquid resistivity in high-Tc superconductors2005Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 71, nr 2, s. 024507-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Analysis of the in-plane resistivity of a Tl2Ba2CaCu2O8+delta thin film and of several oxygen-deficient YBa2Cu3O7-delta single crystals in magnetic fields 0less than or equal toBless than or equal to12 T applied along the crystallographic c axis were performed to study the resistive transition into the glassy state. The transition curves were scaled according to a modified model for the vortex-liquid resistivity, finding good scaling only for fields below a certain value B-0, consistent with the field-induced crossover between a three-dimensional and quasi-two-dimensional regime of the vortex fluctuations reported in several works. This indicates that for low fields the vortex state is in fact three dimensional and provides further support to a coherent description of the vortex-liquid resisitivity.

  • 80.
    Espinosa-Arronte, Beatriz
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Andersson, Magnus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    van der Beek, C. J.
    Laboratoire des Solides Irradiés, CNRS-UMR 7642 and CEA/DSM/DRECAM, Ecole Polytechnique, Palaiseau.
    Nikolaou, Marios
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Lidmar, Jack
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Wallin, Mats
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik.
    Fully anisotropic superconducting transition in ion-irradiated YBa2Cu3O7-delta with a tilted magnetic field2007Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, nr 10, s. 100504-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider the superconducting vortex solid-to-liquid transition in heavy ion-irradiated untwinned YBa2Cu3O7-delta single crystals in the case where the magnetic field direction does not coincide with that of the irradiation-induced linear columnar defects. For a certain range of angles, the resistivities measured in three orthogonal spatial directions vanish at the transition as three clearly different powers of reduced temperature. At previously known second-order phase transitions, scaling of physical quantities has either been isotropic or anisotropic in one direction. Thus, our findings yield evidence for a new type of critical behavior with fully anisotropic critical exponents.

  • 81.
    Espinosa-Arronte, Beatriz
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Djupmyr, Märit
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Andersson, Magnus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Scaling of the B-dependent resistivity for different orientations in Fe doped YBa2Cu3O7-[delta]2005Inngår i: Physica. C, Superconductivity, ISSN 0921-4534, E-ISSN 1873-2143, Vol. 423, nr 1-2, s. 69-73Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The angular dependence of a previously proposed modified model of the vortex glass transition has been investigated. The in-plane resistivity in an optimally oxygen doped YBa2Cu3O7-delta single crystal, doped with 1% Fe, was measured in fields up to 12 T applied with different orientations with respect to the crystallographic c-axis. The transition curves at all orientations were successfully scaled into one curve according to a scaling variable for the normalized resistivity. Characteristic parameters of the model, like the glass transition temperature and the magnetic field B-0, were measured at each orientation and were in good agreement with the expected values. These results show that the model proposed is valid also for fields applied outside the c-axis, giving further support to a more consistent description of the vortex liquid resistivity.

  • 82. Esteve, Romain
    et al.
    Schoner, A.
    Reshanov, S. A.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Nagasawa, H.
    Advanced oxidation process combining oxide deposition and short postoxidation step for N-type 3C- and 4H-SiC2009Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, nr 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electrical properties of oxides fabricated on n-type 3C-SiC (001) and 4H-SiC (0001) epilayers using an advanced oxidation process combining plasma enhanced deposition and rapid postoxidation steps have been investigated. Three gas atmospheres have been studied for the postoxidation steps: N2O, dry, and wet oxygen (H2O). In comparison, additional oxides using postannealing in pure N-2 have been fabricated. The implementation of wet oxygen resulted. in a significant decrease in the interface traps density, in a reduction of oxide fixed charges and in the increased breakdown field in the case of 3C-SiC. In the case of 4H-SiC the postoxidation in N2O is a superior postprocessing step.

  • 83. Esteve, Romain
    et al.
    Schoner, A.
    Reshanov, S. A.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Nagasawa, H.
    Comparative study of thermally grown oxides on n-type free standing 3C-SiC (001)2009Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 106, nr 4Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alternative ways to improve the oxidation process of free standing 3C-SiC (001) are developed and tested with the aim to reduce the fixed and mobile charges in the oxide and at the SiO2/3C-SiC interface. The postoxidation annealing step in wet oxygen (O-2+H-2) is demonstrated to be beneficial for n-type 3C-SiC metal-oxide-semi conductor capacitors resulting in significant reduction in flat band voltage shift, effective oxide charge density, and density of interface traps. The inefficiency of nitridation for the improvement of the oxide quality on 3C-SiC is discussed.

  • 84.
    Fang, Yeyu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Titled and graded anisotropy FePt and FePtCu thin films for the application of hard disk drive and spin torque oscillators2011Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

     The FePt and FePtCu thin films with graded anisotropy and titled anisotropy are utilized to solve both the magnetic recording ‘‘trilemma’’ of the hard disk drives (HDDs) and the large field operation problem of spin torque oscillators (STOs). We have successfully realized the FePtCu thin films with graded anisotropy. During deposition a compositional gradient is achieved by continuously varying the Cu content from the top to bottom. After annealing at proper temperatures, the top Cu-poor regions remain at soft A1 phase, while the bottom Cu-rich regions transform into hard L1 0phase. Hence the gradient anisotropy is established through the film thickness. The critical role of the annealing temperatures (TA) on the resultant anisotropy gradient is investigated. Magnetic measurements support the creation of an anisotropy gradient in properly annealed films which exhibit both the reduced coercivity and moderate thermal stability. In conjunction of the fabrication, the subsequent analysis of the graded material is not trivial. The reversal mechanism of graded anisotropy have been investigated by alternation gradient magnetometer (AGM) and magneto optical Kerr effect (MOKE) measurements with first order reversal curves (FORC) technique. The AGM-FORC analysis, which clearly shows the soft and hard phases, is not able to resolve how these phases are distributed through the film thickness. MOKE-FORC measurement which preferentially probes the surface of the film, reveal that the soft components are indeed located toward the top surface. The TA plays a critical role in the induced anisotropy gradient. We provide a detailed study of the how the anisotropy gradient in a compositional graded FePtCu film gradually develops as a function of the TA. By utilizing the in-situ annealing and magnetic characterization capability of a physical property measurement system, the evolution of the induced anisotropy gradient is elucidated. These results are important and useful for the application of HDDs. In order to achieve the zero-field operation for STOs, we have successfully fabricated pseudo spinvalves based on L1 0(111) textured FePt or FePtCu. We demonstrate magnetoresistance(MR) in excess of 4% in FePt/CoFe/Cu/CoFe/NiFe pseudo spin valves based on L10(111)-oriented FePt fixed layers with a 36 ° out-of-plane tilted magnetization. The high MR is achieved by increasing the spin polarization at the Cu interfaces, using thin CoFe, and optimizing the FePt growth and Cu interface quality using Ta and Ta/Pt underlayers.We observe well-separated switching of the FePt/CoFe fixed layer and the CoFe/NiFe free layer, suggesting that CoFe is rigidly exchange coupled to FePt and NiFe in the respective layers. Futuremore, through optimization of the Cu spacer thickness, we demonstrate MR up to 5% in FePtCu/CoFe/Cu/CoFe/NiFe pseudo spin valves based on L10 (111) FePtCu fixed layers with a tilted magnetization. We find an optimum spacer thickness of about 2.4 nm which correlates with a clear onset of strong interlayer exchange coupling below 2.4 nm and spin-independent current shunting in the spacer above 2.4 nm. These results are an important milestone for future applications of tilted spin polarizers in STOs.

  • 85.
    Fang, Yeyu
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Dumas, Randy K.
    Department of Physics, University of Gothenburg, Sweden.
    Zha, Chaolin
    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.
    An In Situ anneal study of graded anisotropy FePtCu films2011Inngår i: IEEE Magnetics Letters, ISSN 1949-307X, E-ISSN 1949-3088, Vol. 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We provide a detailed study of how the anisotropy (Ku) gradient in a compositionally graded FePtCu film gradually develops as a function of the postannealing temperature (TA). By utilizing the in situ annealing and magnetic characterization capabilities of a physical property measurement system, the evolution of the induced Ku gradient is elucidated. For low TA, the sample primarily remains in the low-Ku A1 phase. At intermediate TA, the gradual development of an A1 to L10 anisotropy gradient occurs. As TA is further increased, a well-developed L10 gradient is realized. Finally, annealing temperatures greater than 475 ◦C reduce the gradient until the film is effectively uniform for TA ≥ 525 ◦C and higher, presumably due to interdiffusion of the Cu through the film thickness. The resulting coercivity shows a nonmonotonic dependence on TA with an initial steep increase as the L10 fraction of the sample increases, a local minimum at TA = 525 ◦C where the gradient vanishes, and a final increase as the uniform L10 film orders completely.

  • 86.
    Fang, Yeyu
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Zha, Chaolin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Bonetti, Stefano
    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.
    FORC studies of exchange biased NiFe in L1(0)(111) FePt-based spin valve2010Inngår i: INTERNATIONAL CONFERENCE ON MAGNETISM (ICM 2009) / [ed] Goll, G; Lohneysen, HV; Loidl, A; Pruschke, T; Richter, M; Schultz, L; Surgers, C; Wosnitza, J, BRISTOL: IOP PUBLISHING LTD , 2010, Vol. 200, s. 072002-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We use First-Order Reversal Curves (FORC) to study the switching distribution and exchange bias in L1(0) (111) FePt-based spin valves with a layer structure of Ta (6)/Pt (3)/L1(0) (111) Fe(53)Pt(47) (20)/Co(50)Fe(50) (1.5)/Cu (4.5)/Co(50)Fe(50) (2)/Ni(80)Fe(20)(3) (in nm). We find that the switching of the free layer magnetization is strongly influence by the magnetic state of the FePt/CoFe fixed layer, as evidenced by tunable coercivity and exchange bias fields.

  • 87.
    Fang, Yuntuan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Lin, Zhili
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    ENHANCEMENT OF THE DEFECT FIELD OF ONE-DIMENSIONAL PHOTONIC CRYSTALS CONTAINING epsilon- AND mu-NEGATIVE LAYERS2008Inngår i: Journal of Russian Laser Research, ISSN 1071-2836, E-ISSN 1573-8760, Vol. 29, nr 5, s. 460-465Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Employing the transfer matrix method, we study the electromagnetic field of one-dimensional photonic crystals with a defect inserted by pairs of mu-negative (MNG) and epsilon-negative (ENG) material layers. The fields within the pairs of layers and the matrix defect are independent of each other, and the whole field is their superposition. The whole defect field can be significantly enhanced by pairs of epsilon-negative and mu-negative layers. In contrast to the conventional defect modes, the intensity and volume of the defect field with pairs of epsilon-negative and mu-negative layers can be precisely adjusted.

  • 88.
    Friberg, Ari T.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Partial polarization and coherence in arbitrary electromagnetic fields2008Inngår i: RIAO/OPTILAS 2007 / [ed] Wetter, NU; Frejlich, J, 2008, Vol. 992, s. 460-465Konferansepaper (Fagfellevurdert)
    Abstract [en]

    While the theories of optical coherence for scalar fields and partial polarization for beam-like waves are well developed and unambiguous, this is not so for partial coherence in random electromagnetic waves and partial polarization in fields that contain all three electric-field components. Examples of such three-dimensional vector waves are optical near fields with evanescent components and high-numerical-aperture focused electromagnetic fields. Interesting new results on arbitrary electromagnetic coherence and polarization have been obtained, for instance, in Young's two-pinhole interference setup. In this paper some recent unusual and physically unexpected results on randomly fluctuating electromagnetic fields are discussed and the current development on the basic concepts of partial polarization and partial electromagnetic coherence is reviewed.

  • 89.
    Friberg, Ari T.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Turunen, Jari
    Univ Eastern Finland, Dept Math & Phys, FI-80101 Joensuu, Finland..
    Optics communications special issue "electromagnetic coherence and polarization"2010Inngår i: Optics Communications, ISSN 0030-4018, E-ISSN 1873-0310, Vol. 283, nr 22, s. 4423-4426Artikkel i tidsskrift (Annet vitenskapelig)
  • 90.
    Friberg, Ari
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Tervo, Jani
    Setälä, Teri
    Young's interference experiment reloaded2007Inngår i: 6th International Workshop on Information Optics, WIO'07 / [ed] Benediktsson, JA; Javidi, B; Gudmundsson, KS, 2007, Vol. 949, s. 130-137Konferansepaper (Fagfellevurdert)
    Abstract [en]

    An electromagnetic Young's interference experiment is considered with arbitrary, spectrally partially coherent and partially polarized electric fields at the pinholes. Any correlations that exist at the openings lead to modulations of the Stokes parameters on the observation screen. The electromagnetic degree of coherence can be viewed, in direct analogy to the usual scalar case, as a measure of the modulation contrasts of not just the optical intensity but also the polarization state. The electromagnetic degree of coherence can be obtained experimentally via four visibility measurements using appropriate wave plates. If the field at the pinholes is fully polarized, a periodic variation of the polarization state appears on the observation screen, leading to a Pancharatnam-Berry phase. It is shown that this geometric phase has a straightforward but elegant relationship to the Stokes parameters at the pinholes.

  • 91.
    Fu, Ying
    et al.
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Ågren, Hans
    KTH, Skolan för bioteknologi (BIO), Teoretisk kemi (stängd 20110512).
    Andersson, J. Y.
    Asplund, C.
    Qiu, Min
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Thylén, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101).
    Optical reflection from excitonic quantum-dot multilayer structures2008Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, nr 18, s. 183117-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study theoretically and experimentally the optical reflection from excitonic quantum-dot (QD) multilayer structures composed of InAs QDs in a GaAs substrate. Quantum mechanical and finite-difference time-domain numerical calculations indicate that the incident radiation in the optical reflectance measurement photoexcites the InAs QDs which then form excitonic dipoles. The excitonic dipole modifies significantly the dielectric constant of the QD, which results in a reflectance peak in the vicinity of the excitonic energy, as observed experimentally.

  • 92.
    Furberg, Richard
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Li, Shanghua
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Toprak, Muhammet
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Muhammed, Mamoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Funktionella material, FNM.
    Dendritically ordered nano-particles in a micro-porous structure for enhanced boiling2006Inngår i: Proceedings of 13th International Heat Transfer Conference, NAN-07, 2006, Vol. NAN-07Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Presented research is an experimental study of the pool boiling performance of copper surfaces enhanced with a newly developed structure. The enhanced surfaces were fabricated with an electrodeposition method where metallic nano-particles are formed and dendritically connected into an ordered micro-porous structure. To further alter the grain size of the dendritic branches, some surfaces underwent an annealing treatment. The tests were conducted with the test objects horizontally oriented and submerged in a refrigerant: R134A, at saturated conditions and at an absolute pressure of 4 bar. The heat flux varied between 0.1 and 10 W/cm2. The boiling performance of the enhanced surfaces was found to be dependent on controllable surface characteristics such as thickness of the structure and the interconnectivity of the grains in the dendritic branches. Temperature differences less than 0.3 °C and 1.5 °C at heat fluxes of 1 and 10 W/cm2 respectively have been recorded, corresponding to heat transfer coefficients up to 7.6 Wcm-2K-1. The micro-porous structure has been shown to facilitate high performance boiling, which is attributed to its high porosity (∼94%), a dendritically formed and exceptionally large surface area, and to a high density of well suited vapor escape channels (50 – 470 per mm2).

  • 93. Gabrysch, Markus
    et al.
    Majdi, Saman
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Linnarsson, Margareta K
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Schoner, Adolf
    Twitchen, Daniel
    Isberg, Jan
    Compensation in boron-doped CVD diamond2008Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hall-effect measurements on single crystal boron-doped CVD diamond in the temperature interval 80-450 K are presented together with SIMS measurements of the dopant concentration. Capacitance-voltage measurements on rectifying Schottky junctions manufactured on the boron-doped structures are also presented in this context. Evaluation of the compensating donor (N-D) and acceptor concentrations (N-A) show that in certain samples very low compensation ratios (N-D/N-A below 10(-4)) have been achieved. The influence of compensating donors on majority carrier transport and the significance for diamond device performance are briefly discussed.

  • 94. Galeckas, A.
    et al.
    Hallén, Anders.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Majdi, S.
    Linnros, Jan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Pirouz, P.
    Combined photoluminescence-imaging and deep-level transient spectroscopy of recombination processes at stacking faults in 4H-SiC2006Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, nr 23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on electronic properties of single- and double-layer stacking faults in 4H-SiC and provide an insight into apparent distinctions of recombination-enhanced defect reactions at these faults. Photoluminescence imaging spectroscopy and deep-level transient spectroscopy experiments reveal key constituents of radiative recombination and also provide firm evidence of nonradiative centers at E-V+0.38 eV responsible for recombination-enhanced mobility of silicon-core partial dislocations. A comprehensive energy level model is proposed allowing for a qualitative description of recombination activity at different types of stacking faults and the corresponding bounding partial dislocations.

  • 95. Gautier, S.
    et al.
    Aggerstam, Thomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Pinos, Andrea
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Marcinkevicius, Saulius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, 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 gas2008Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 310, nr 23, s. 4927-4931Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 96.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Kolahdouz, Mohammadreza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Hållstedt, Julius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Lu, Jun
    Wise, R.
    Wejtmans, H.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    High boron incorporation in selective epitaxial growth of SiGe layers2007Inngår i: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 18, nr 7, s. 747-751Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Incorporation of high amount of boron in the range of 1 x 10(20)-1 x 10(21) cm(-3) in selective epitaxial growth (SEG) of Si1-xGex (x = 0.15-0.315) layers for recessed or elevated source/drain junctions in CMOS has been studied. The effect of high boron doping on growth rate, Ge content and appearance of defect in the epi-layers was investigated. In this study, integration issues were oriented towards having high layer quality whereas still high amount of boron is implemented and the selectivity of the epitaxy is preserved.

  • 97.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    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), Integrerade komponenter och kretsar.
    Ostling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Simultaneous study of nickel based ohmic contacts to Si-face and C-face of n-type silicon carbide2007Inngår i: 2007 INTERNATIONAL SEMICONDUCTOR DEVICE RESEARCH SYMPOSIUM, VOLS 1 AND 2, NEW YORK: IEEE , 2007, s. 311-311Konferansepaper (Fagfellevurdert)
  • 98.
    Ghandi, Reza
    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.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Backside Nickel Based Ohmic Contacts to n-type Silicon Carbide2009Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 600-603, s. 635-638Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work focuses on Ni ohmic contacts to the C-face (backside) of n-type 4H-SiC substrates. Low-resistive ohmic contacts to the wafer backside are important especially for vertical power devices. Ni contacts were deposited using E-beam evaporation and annealed at different temperatures (700-1050 degrees C) in RTP to obtain optimum conditions for forming low resistive ohmic contacts. Our results indicate that 1 min annealing at temperatures between 950 and 1000 degrees C provides high quality ohmic contacts with a contact resistivity of 2.3x10(-5) Omega cm(2). Also our XRD results show that different Ni silicide phases appear in this annealing temperature range.

  • 99. Gholami, M.
    et al.
    Esmaeili, M.
    Haratizadeh, H.
    Holtz, P. O.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Evaluation of optical quality and properties of Ga0.64In0.36N0.006As0.994 lattice matched to GaAs by using photoluminescence spectroscopy2009Inngår i: Opto-Electronics Review, ISSN 1230-3402, E-ISSN 1896-3757, Vol. 17, nr 3, s. 260-264Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have investigated optical properties of Ga0.64In0.36N0.006As0.994/GaAs single quantum-well structures using photoluminescence technique. We have found that nitrogen creates potential fluctuations in the InGaNAs structures, so it is the cause of trap centres in these structures and leads to localized excitons recombination dynamics. The near-band edge PL at 2 K exhibited a blueshift with an increase in excitation intensity of a sample but there is not such a shift in the PL peak position energy of same sample at 150 K. It has been found that PL spectra have a large full width at half maximum (FWHM) value at 2 K. These results are discussed in terms of carrier localization. Additionally, our results suggest decreasing PL integrated intensity in this structure, possibly due to non-radiative recombination. It has been shown that thermal annealing reduces the local strain created by nitrogen. By annealing process, a blue shifted emission can be observed.

  • 100. Gholami, M.
    et al.
    Haratizadeh, H.
    Esmaeili, M.
    Amiri, R.
    Holtz, P. O.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Alternation of band gap and localization of excitons in InGaNAs nanostructures with low nitrogen content2008Inngår i: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 19, nr 31Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Continuous wave photoluminescence (cw PL) spectroscopy has been used to study the optical properties of a set of InGaNAs epilayers and single quantum wells with nitrogen concentration less than a few per cent at different temperatures and different excitation powers. We found that nitrogen has a critical role on the emission light of InGaNAs nanostructures and the recombination mechanism. The incorporation of a few per cent of nitrogen leads to shrinkage of the InGaNAs band gap. The physical origin of such band gap reduction has been investigated both experimentally and theoretically by using a band anticrossing model. We have found that localization of excitons that have been caused by incorporation of a few per cent of nitrogen in these structures is the main explanation of such anomalous behavior observed in the low-temperature photoluminescence spectra of these nanostructures. The localization energies of carriers have been evaluated by studying the variation of the quantum well (QW) emission versus temperature, and it was found that the localization energy increases with increasing nitrogen composition. Our data also show that, with increasing excitation intensity, the PL peak position moves to higher energies (blue shift) due to the filling of localized states and capture centers for excitons by photo-generated carriers.

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