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  • 101.
    Blomqvist, Mats
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Petraru, Adrian
    Inst. of Thin Films and Interfaces, Section: Ion Technology, Forschungszentrum Jülich.
    Buchal, Christoph
    Inst. of Thin Films and Interfaces, Section: Ion Technology, Forschungszentrum Jülich.
    Optical waveguiding in magnetron-sputtered Na0.5K0.5NbO3 thin films on sapphire substrates2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 3, p. 439-441Article in journal (Refereed)
    Abstract [en]

    Preferentially oriented perovskite-structured Na0.5K0.5NbO3 (NKN) thin films have been deposited on hexagonal Al2O3(01 (1) under bar2) substrates using rf magnetron sputtering of a stoichiometric, high-density, ceramic target. Structural and film surface properties were measured using x-ray diffraction and atomic force microscopy, respectively. Optical and waveguiding properties were characterized using a prism-coupling technique. We observed sharp and distinguishable TM and TE propagation modes and measured the refractive index of NKN thin films of different thicknesses. The ordinary and extraordinary refractive indices were calculated to be n(o)=2.247+/-0.002 and n(e)=2.216+/-0.002 for a 2.0-mum-thick film at 632.8 nm. This implies a birefringence Deltan=n(e)-n(o)=-0.031+/-0.002 in the film. These first results show the potential use of rf-sputtered NKN films as an electro-optical active material.

  • 102.
    Blomqvist, Mats
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Koh, Jung-Hyuk
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Rf-magnetron sputtered ferroelectric (Na,K)NbO3 films2002In: Proceedings of the 13th IEEE International Symposium on Applications of Ferroelectronics / [ed] White, G.; Tsurumi, T., 2002, p. 195-198Conference paper (Refereed)
    Abstract [en]

    Sodium potassium niobate (Na,K)NbO3 (NKN) thin films were grown by rf-magnetron sputtering from stoichiometric Na0.5K0.5NbO3 target on LaAlO3 (LAO) single crystals and polycrystalline Pt80Ir20 (PtIr) substrates. NKN films on polycrystalline PtIr substrates were found to be preferentially (004 oriented while XRD measurements reveal epitaxial quality of NKN/LaAlO3 film structures. The ferroelectric state in NKN/PtIr films at room temperature is indicated by polarization loops with polarization as high as 33.4 muC/cm(2) at 700 kV/crn, remnant polarization of 9.9 muC/cm(2), and coercive field of 91 kV/cm. I-V characteristics of vertical Au/NKN/PtIr capacitive cells and planar Au/NKN/LAO interdigital capacitors (IDCs) showed very good insulating properties. For NKN IDC the leakage current density was in the order of 30 nA/cm(2) at 400 kV/cm. Rf dielectric spectroscopy demonstrates low loss, low frequency dispersion, and high voltage tunability both for vertical Au/NKN/PtIr and planar interdigital Au/NKN/LAO capacitors.

  • 103.
    Blomqvist, Mats
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Koh, Jung-Hyuk
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Andréasson, Johanna
    Department of Materials and Manufacturing Engineering, Luleå University of Technology.
    High-performance epitaxial Na0.5K0.5NbO3 thin films by magnetron sputtering2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 81, no 2, p. 337-339Article in journal (Refereed)
    Abstract [en]

    Epitaxial Na0.5K0.5NbO3 (NKN) thin films have been grown on LaAlO3 substrates by rf magnetron sputtering of a stoichiometric, high-density, ceramic target. X-ray diffraction analysis showed c-axis oriented cube-on-cube growth. Micrometer size interdigital capacitor (IDC) structures were defined on the surface of the NKN film using photolithography. The electrical characterization at 1 MHz showed dissipation factor tan delta of 0.010, tunability 16.5% at 200 kV/cm and dielectric permittivity epsilon(r)=470. The frequency dispersion of epsilon(r) between 1 kHz and 1 MHz was 8.5% and the IDCs showed very good insulating properties with leakage current density on the order of 30 nA/cm(2) at 400 kV/cm. The polarization loop exhibits weak ferroelectric hysteresis with maximum polarization 23.5 muC/cm(2) at 600 kV/cm. These results are promising for tunable microwave devices based on rf sputtered NKN thin films.

  • 104. Bourennane, M.
    et al.
    Karlsson, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Björk, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Quantum key distribution using multilevel encoding2001In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 6401, no 1Article in journal (Refereed)
    Abstract [en]

    In this article, protocols for quantum key distribution based on encoding in higher dimensional systems in N-dimensional Hilbert space are proposed. We extend the original Bennett-Brassard protocol using two complementary bases and two-dimensional states to M mutually complementary bases and N orthogonal vectors in each base. We study the mutual information between the legitimate parties and the eavesdropper and the error rate by considering various incoherent eavesdropping attacks as a function of the dimension of the Hilbert space.

  • 105. Bourennane, M.
    et al.
    Karlsson, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Björk, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Gisin, N.
    Cerf, N. J.
    Quantum key distribution using multilevel encoding: security analysis2002In: Journal of Physics A: Mathematical and General, ISSN 0305-4470, E-ISSN 1361-6447, Vol. 35, no 47, p. 10065-10076Article in journal (Refereed)
    Abstract [en]

    We propose an extension of quantum key distribution based on encoding the key into quNits, i.e. quantum states in an N-dimensional Hilbert space. We,estimate both the mutual information between the legitimate parties and the eavesdropper, and the error rate, as a function of the dimension of the Hilbert space. We derive the information gained by an eavesdropper using optimal incoherent attacks and an upper bound on the legitimate party error rate that ensures unconditional security when the eavesdropper uses finite coherent eavesdropping attacks. We also consider realistic systems where we assume that the detector dark count probability is not negligible.

  • 106. Bourennane, M.
    et al.
    Karlsson, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ciscar, J. P.
    Mathes, M.
    Single-photon counters in the telecom wavelength region of 1550 nm for quantum information processing2001In: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 48, no 13, p. 1983-1995Article in journal (Refereed)
    Abstract [en]

    We describe the status of commercially available InGaAs/InP avalanche photodiodes for use as single-photon counters in the telecom wavelength region of 1550 nm.

  • 107.
    Bourennane, Mohamed
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Long wavelength quantum cryptography, single-photon detection and quantum entanglement applications2001Doctoral thesis, comprehensive summary (Other scientific)
  • 108. Bowallius, O.
    et al.
    Anand, Srinivasan
    KTH, Superseded Departments, Electronics.
    Nordell, N.
    Landgren, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Karlsson, S.
    Scanning capacitance microscopy investigations of SiC structures2001In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 4, no 03-jan, p. 209-211Article in journal (Refereed)
    Abstract [en]

    We have applied scanning capacitance microscopy (SCM) to investigate SIC structures grown by vapour-phase epitaxy. The SCM technique is evaluated using n- and p-type doping staircase structures with doping concentrations ranging from 10(16) to 10(20) cm(-3). The n- and p-type doping was obtained by doping SiC with nitrogen and aluminium, respectively. The sample cross-sections for SCM were obtained by simple cleaving. For doping levels above 10(17) cm(-3) the SCM data are consistent with doping data obtained independently from secondary ion mass spectroscopy (SIMS). Treating the samples with diluted hydrofluoric acid significantly improves the SCM signal for the low-doped regions. The SCM technique has been used to investigate doping redistribution in patterned regrowth of n- and p-type SIC around dry-etched mesas. In both cases, contrast variations were seen close to the mesa walls, indicative of doping variations; lower and higher incorporation for p- and n-type, respectively. The observations are shown to be consistent with the expected trends in dopant incorporation in the SiC material.

  • 109.
    Bowallius, Olle
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Scanning capacitance microscopy for semiconductor characterisation2001Licentiate thesis, comprehensive summary (Other scientific)
  • 110. Bratus, V. Y.
    et al.
    Petrenko, T. T.
    von Bardeleben, H. J.
    Kalinina, E. V.
    Hallén, Anders.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Vacancy-related defects in ion-beam and electron irradiated 6H-SiC2001In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 184, no 04-jan, p. 229-236Article in journal (Refereed)
    Abstract [en]

    A brief review is given on EPR study of irradiation-induced defects in SiC. The results of low-temperature study of Ky1 and Ky2 centers reveal for both of them the C-S symmetry, spin S = 1/2 and close coincidence of the g-tensor components. For Ky2 defect the principal values of g-tensor have been determined as g(z) = 2.0048, g(x) = 2.0022 and g(y) = 2.0037, where z and x directions reside in the (11 (2) over bar0) plane and the z-axis makes up an angle 65 degrees with the c-axis. The same residence of z- and x-axis and an angle 59 degrees are found for Ky1 center, g(z) = 2.0058, g(x) = 2.0025 and g(y) = 2.0023. A comparison of experimental and calculated hyperfine (HF) parameters is presented which suggests that Ky2 and Ky1 defects can be assigned to the positively charged carbon vacancy in 6H-SiC. The EPR study of defects created along the Al+ ion track in n-type 6H-SiC shows that lineshape, linewidth and integral intensity of the EPR signal reflect the state of damaged layer generated by ion implantation. A variation of defect density with annealing is reported and defect origin is discussed.

  • 111.
    Bria, Aurelian
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Flament, Maxime
    Chalmers University of Technology.
    Gessler, Fredrik
    KTH, Superseded Departments, Industrial Economics and Management.
    Queseth, Olav
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stridh, Rickard
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Unbehaun, Matthias
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Wu, Jiang
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zander, Jens
    KTH, Superseded Departments, Wireless at KTH.
    Overall design of 4th Generation Wireless Infrastructures (4GW)2002Conference paper (Refereed)
    Abstract [en]

    An important factor contributing to this uncertainty is that we have very limited knowledge about the future environment in which a fourth generation wireless infrastructure should function. Which of today's systems will still exist when a potential 4G infrastructure is deployed? Which systems and solutions will be considered successful then? What technical bottlenecks will be apparent ten years from now? What market impact will third generation wireless systems have? How will this affect user behavior, and user demands? How much money do prospective users have available to pay for services provided over this infrastructure? This paper presents some of the conclusion of of the Fourth Generation Wireless Infrastructure project (4GW) of the Personal Computing and Communications program (PCC), the major Swedish academic research effort on future communications systems launched in late 1997(1). The vision of the PCC project has been "Personal Multimedia to everyone at today's prices for fixed telephony". In 4GW a scenario-based approach has been used to tackle the issue of identifying reasonable research topics. In the paper we will present this method, and demonstrate how it interfaces with traditional research methods in the fields that the 4GW project incorporates. We will also give an overview of some research results from the project. Finally, we will conclude these results as a vision of what fourth generation wireless infrastructures might become

  • 112.
    Bria, Aurelian
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Gessler, Fredrik
    KTH, Superseded Departments, Industrial Economics and Management.
    Queseth, Olav
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Stridh, Rickard
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Unbehaun, Matthias
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Wu, Jiang
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zander, Jens
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Flament, Maxime
    Chalmers University of Technology.
    4th Generation Wireless Infrastructures: Scenarios and Research Challenges2001In: IEEE personal communications, ISSN 1070-9916, E-ISSN 1558-0652, Vol. 8, no 6, p. 25-31Article in journal (Refereed)
    Abstract [en]

    A "fourth generation" of wireless systems, likely to appear after the successful deployment of the current third-generation systems, is frequently debated these days. This article presents some of the results of the Fourth Generation Wireless project (4GW) of the Personal Computing and Communications program (PCC), the major Swedish academic research effort on future communications systems, launched in late 1997. In the 4GW project, scenarios have been used as tools for formulating relevant research topics related to future wireless systems. By working with scenarios the project group has been able to challenge some of the assumptions commonly made in the field of wireless research. Since the project group is multidisciplinary, the work has also helped the members of the project group to understand the differences between the research traditions to which they belong. The scenarios, as well as the ensuing research into various wireless related topics, point to a vision of fourth-generation systems where "low-hierarchy" user-deployed infrastructures are the prime candidate. Fourth-generation systems will offer short- to moderate-range communications with very high data rates (>100 Mb/s). They are likely to employ array signal processing and ad hoc operation to provide the required coverage. A key aspect of their design will be the fact that they will be deployed in environments where large-scale wireless, and wired, infrastructures are already in operation.

  • 113. Brookes, N. B.
    et al.
    Ghiringhelli, G.
    Tjernberg, Oscar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Tjeng, L. H.
    Mizokawa, T.
    Li, T. W.
    Menovsky, A. A.
    Detection of Zhang-Rice singlets using spin-polarized photoemission2001In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 8723, no 23Article in journal (Refereed)
    Abstract [en]

    From a spin-resolved photoemission study on the Bi2Sr2CaCu2O8+delta superconductor, we show experimentally that the first ionization state is of nearly pure singlet character. This is true both above and below the superconducting transition and in the presence of doping and band formation. This provides direct support for the existence and stability of Zhang-Rice singlets in high-temperature superconductors, justifying the ansatz of single-band models. Moreover, we establish this technique as an important probe for a wide range of cuprates and strongly correlated materials.

  • 114. Brunahl, J.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Piezoelectric shear mode drop-on-demand inkjet actuator2002In: Sensors and Actuators A-Physical, ISSN 0924-4247, E-ISSN 1873-3069, Vol. 101, no 3, p. 371-382Article in journal (Refereed)
    Abstract [en]

    We report on comprehensive characterization of piezoelectric shear mode inkjet actuators micromachined into bulk Pb(Zr0.53Ti0.47)O-3 (PZT) ceramics. The paper starts with an overview of different drop-on-demand inkjet systems, whereas the main attention is then turned on particular Xaar-type piezoelectric shear mode inkjet printheads. They are an example of complex microelectromechanical system (MEMS) and comprise a ferroelectric array of 128 active ink channels (75 mum wide and 360 mum deep). Detailed information about fabrication process and principles of operation are given. Since each actuating wall of 128 channels is a piezoelectric capacitor metallized from both sides to be animated by electric pulse, electrical properties of channel walls (CWs) are easy to test and serve as a fingerprint of actuator performance in the virgin state as well as after high voltage/elevated temperature heavy duties. We present several techniques to control manufacturing process and fatigue effects. So, continuous wave and pulsed spectroscopy and hysteresis P-E loop tracing showed that compared to a virgin PZT ceramics state, dielectric permittivity (epsilon') was reduced three times, the loss factor (tan delta) increased from initial 4.8 to 6.6%, remnant polarization decreased by 43%, coercive field increased by 38%, whereas Curie temperature increased from 508 to 560 K after 90,000 cycles of ferroelectric hysteresis P-E loop tracing at 50 Hz at electric field of 88.5 kV/cm. Heat treatment also results in PZT ceramics degradation: appreciable reduction of the coupling coefficient (k(15)) and the degradation of inkjet performance were revealed by optical stroboscope technique: 8.7 and 14% reduction of drop velocity and volume in electrically fatigued actuator, 2.5% reduction of drop velocity and unchanged drop volume in temperature-treated actuators.

  • 115. Brunahl, J.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Khartsev, Sergiy
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Non-destructive pulsed technique to characterize functional properties of micromachined bulk PZT2001In: Ferroelectrics (Print), ISSN 0015-0193, E-ISSN 1563-5112, Vol. 263, no 1-4, p. 1487-1492Article in journal (Refereed)
    Abstract [en]

    In this report, a non-destructive pulsed technique is presented to characterize all relevant properties of machined bulk PZT material. The proposed method is based on recording of the transient current as response on the short voltage pulse applied to the ferroelectric acoustic element. This new promising experimental technique makes it possible to measure mechanical and electrical properties fast, reliably and reproducibly. Among other results we can obtain electromechanical coupling coefficient, dielectric loss factor tan 8, mechanical quality factor Q, dielectric constant, capacitance, resonant frequency and Curie temperature T-c. The temperature dependence of above mentioned parameters can be studied as well very easily.

  • 116. Brunner, M
    et al.
    Galis, A
    Cheng, L
    Colas, J A
    Ahlgren, B
    Gunnar, A
    Abrahamsson, H
    Szabo, R
    Csaba, S
    Nielsen, J
    Prieto, Alberto Gonzalez
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Stadler, Rolf
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Molnar, G
    Ambient networks management challenges and approaches2004In: MOBILITY AWARE TECHNOLOGIES AND APPLICATIONS, PROCEEDINGS / [ed] Karmouch, A; Korba, L; Madeira, ERM, BERLIN: SPRINGER , 2004, Vol. 3284, p. 196-216Conference paper (Refereed)
    Abstract [en]

    System management addresses the provision of functions required for controlling, planning, allocating, monitoring, and deploying the resources of a network and of its services in order to optimize its efficiency and productivity and to safeguard its operation. It is also an enabler for the creation and sustenance of new business models and value chains, reflecting the different roles the service providers and users of a network can assume. Ambient Network represents a new networking approach and it aims to enable the cooperation of heterogeneous networks, on demand and transparently, to the potential users, without the need for pre-configuration or offline negotiation between network operators. To achieve these goals, ambient network management systems have to become dynamic, adaptive, autonomic and responsive to the network and its ambience. This paper discusses relationships between the concepts of autonomous and self-manageability and those of ambient networking, and the challenges and benefits that arise from their employment.

  • 117. Brunschen, C.
    et al.
    Brorsson, Mats
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    OdinMP/CCp - a portable implementation of OpenMP for C2000In: Concurrency, ISSN 1040-3108, E-ISSN 1096-9128, Vol. 12, no 12, p. 1193-1203Article in journal (Refereed)
    Abstract [en]

    We describe here the design and performance of OdinMP/CCp, which is a portable compiler for C-programs using the OpenMP directives for parallel processing with shared memory. OdinMP/CCp was written in Java for portability reasons and takes a C-program with OpenMP directives and produces a C-program for POSIX threads. We describe some of the ideas behind the design of OdinMP/CCp and show some performance results achieved on an SGI Origin 2000 and a Sun E10000, Speedup measurements relative to a sequential version of the test programs show that OpenMP programs using OdinMP/CCp exhibit excellent performance on the Sun E10000 and reasonable performance on the Origin 2000,

  • 118.
    Brünahl, Jürgen
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Characterization of piezoelectric shear modeinkject actuator2002Licentiate thesis, comprehensive summary (Other scientific)
  • 119.
    Brünahl, Jürgen
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Physics of piezoelectric shear mode inkjet actuators2003Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    This thesis describes work on piezoelectric shear modeactuators used in dropon- demand ink printing applications.These actuators comprise an array of ink channels micromachinedinto bulk Pb(ZrxTi1-x)O3(PZT) ceramics.

    During this study, a new pulsed spectroscopic technique wasdeveloped to investigate functional properties of a singlechannel wall of the actuator. The pulse technique is based onrecording the transient current in response to a short voltagepulse applied to the channel wall. An electric field appliedperpendicular to the polarization will cause a shear motion ofthe wall. If a voltage pulse with a fast rise time is highenough in amplitude to actuate the wall, it will act like atuning fork and oscillate at it’s resonant frequencies.Because of the piezoelectric effect, the mechanicaloscillations of the wall can be seen as oscillations in thetransient current.

    Beside the pulsed technique, dielectric spectroscopy,ferroelectric hysteresis loop tracing and stroboscopy were usedas characterization techniques. The results obtained arediscussed in respect to temperature dependence, frequencydispersion, ferroelectric fatigue and acoustic resonancemodes.

    Another field of interest was the temperature inside theactuator. An electric circuit, based on the voltage dividerprinciple, was built to monitor the ink temperature as afunction of the printing pattern.‘Dummy walls’,located at the beginning and the end of the channel wall array,were used as temperature sensing elements. Since the dielectricpermittivity of the PZT channel walls depends on temperature,the capacitance of the‘dummy walls’changes withtemperature. The information obtained by this measurementtechnique was used to investigate alternative materials for thepassive components of the actuator.

    A further part was the development of a new actuator designcalled a‘Chevron actuator’. Chevron actuatorsinclude an additional PZT layer with polarization in theopposite direction to the base plate polarization. Thus, thewhole channel wall is used as the active part instead of usingjust the upper half as in the standard actuator. The mainadvantage of this technique is a reduced power consumption ofthe actuator and therefore less heat dissipation.

    Different approaches were used to construct Chevronactuators. Experiments determined the efficiency of theactuators and these results were used to make improvements. TheChevron actuators were characterized by the above mentionedtechniques and compared with standard Xaar actuators.

  • 120.
    Burvall, Anna
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Axicon imaging by scalar diffraction theory2004Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Axicons are optical elements that produce Bessel beams,i.e., long and narrow focal lines along the optical axis. Thenarrow focus makes them useful ine.g. alignment, harmonicgeneration, and atom trapping, and they are also used toincrease the longitudinal range of applications such astriangulation, light sectioning, and optical coherencetomography. In this thesis, axicons are designed andcharacterized for different kinds of illumination, using thestationary-phase and the communication-modes methods.

    The inverse problem of axicon design for partially coherentlight is addressed. A design relation, applicable toSchell-model sources, is derived from the Fresnel diffractionintegral, simplified by the method of stationary phase. Thisapproach both clarifies the old design method for coherentlight, which was derived using energy conservation in raybundles, and extends it to the domain of partial coherence. Thedesign rule applies to light from such multimode emitters aslight-emitting diodes, excimer lasers and some laser diodes,which can be represented as Gaussian Schell-model sources.

    Characterization of axicons in coherent, obliqueillumination is performed using the method of stationary phase.It is shown that in inclined illumination the focal shapechanges from the narrow Bessel distribution to a broadasteroid-shaped focus. It is proven that an axicon ofelliptical shape will compensate for this deformation. Theseresults, which are all confirmed both numerically andexperimentally, open possibilities for using axicons inscanning optical systems to increase resolution and depthrange.

    Axicons are normally manufactured as refractive cones or ascircular diffractive gratings. They can also be constructedfrom ordinary spherical surfaces, using the sphericalaberration to create the long focal line. In this dissertation,a simple lens axicon consisting of a cemented doublet isdesigned, manufactured, and tested. The advantage of the lensaxicon is that it is easily manufactured.

    The longitudinal resolution of the axicon varies. The methodof communication modes, earlier used for analysis ofinformation content for e.g. line or square apertures, isapplied to the axicon geometry and yields an expression for thelongitudinal resolution. The method, which is based on abi-orthogonal expansion of the Green function in the Fresneldiffraction integral, also gives the number of degrees offreedom, or the number of information channels available, forthe axicon geometry.

    Keywords:axicons, diffractive optics, coherence,asymptotic methods, communication modes, information content,inverse problems

  • 121.
    Burvall, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Kolacz, K.
    Jaroszewicz, Z.
    Friberg, Ari T.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Simple lens axicon2004In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 43, no 25, p. 4838-4844Article in journal (Refereed)
    Abstract [en]

    We present the design of a cemented doublet-lens axicon made from spherical surfaces only. Compared with diffractive axicons, refractive cone axicons, and earlier lens axicons with aspheric surfaces, this element is inexpensive and easy to manufacture even with large apertures. The lens axicon is based on the deliberate use of the spherical aberration of the surfaces. The design principles of the element and its characterization, numerically and experimentally, are presented in detail. Although performance was traded for simplicity and robustness, the results show that the lens axicon has the main axicon properties: a narrow, extended line focus of relatively constant width.

  • 122.
    Burvall, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Martinsson, Per
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Communication modes applied to axicons2004In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 12, no 3, p. 377-383Article in journal (Refereed)
    Abstract [en]

    The communication modes, which constitute a convenient method for the propagation and information analysis of optical fields, are formulated in the generalized axicon geometry. The transmitting region is the axicon’s annular aperture, and the observation domain is the optical axis containing the focal line segment. We show that in rotational symmetry one may employ the prolate spheroidal wave functions to represent the communication modes. Further, in usual circumstances the modes can be approximated by quadratic waves in the aperture domain and by sinc functions in the image domain. Both the exact communication modes and the approximate technique are confirmed numerically, with linear axicons as examples.

  • 123.
    Burvall, Anna
    et al.
    Applied Optics, Dept. of Experimental Physics, National University of Ireland, Galway, University Road, Galway, Ireland.
    Martinsson, Per
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Communication modes for information content analysis2004In: LFNM 2004: PROCEEDINGS OF THE 6TH INTERNATIONAL CONFERENCE ON LASER AND FIBER-OPTICAL NETWORKS MODELING / [ed] Sukhoivano, IA, IEEE conference proceedings, 2004, p. 112-114Conference paper (Other academic)
    Abstract [en]

    Approximate modes which give physical understanding for the communication modes theory,are discussed. For the geometry consisting of two line or square apertures, perpendicular to the optical axis, this approximation leads to exactly the same modes as Gabor's theory would yield.

  • 124.
    Burvall, Anna
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Martinsson, Per
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Friberg, Ari T.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Communication modes in axicon imaging2004In: Riao/Optilas 2004: 5th Iberoamerican Meeting On Optics And 8th Latin American Meeting On Optics, Lasers, And Their Applications, Pts 1-3: Ico Regional Meeting / [ed] Marcano, A; Paz, JL, 2004, Vol. 5622, p. 1133-1137Conference paper (Refereed)
    Abstract [en]

    The communication modes are an increasingly frequently used technique for studying the radiation, propagation, and scattering of light. The method is unusual in the way that it gives the information content and the resolution of the fields. It also allows for the possibility of including the noise considerations in the calculations. We present a brief summary of the communication modes method, together with our latest contribution: the communication modes for the axicon geometry.

  • 125.
    Campi, Roberta
    et al.
    Turin Technology Center.
    Berggren, Jesper
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Buccieri, Aurelio
    Turin Technology Center.
    Gotta, Paola
    Turin Technology Center.
    Landgren, Gunnar
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Sarocchi, Davide
    Turin Technology Center.
    Valenti, P.
    Turin Technology Center.
    Lateral confinement optimisation of 1300 nm InGaAlAsP/InGaAsP Fabry-Perot lasers2003In: EWMOVPEX: 10th European Workshop on Metalorganic Vapour Phase Epitaxy, 2003Conference paper (Refereed)
  • 126.
    Cao, J.
    et al.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Broeke, R. G.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Fontaine, N.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Cong, W.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Ji, C.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Du, Y.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Chubun, N.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Aihara, K.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Pharn, Anh-Vu
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Heritage, J. P.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Kolner, B. H.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Yoo, S. J. B.
    Univ Calif Davis, Dept Elect & Comp Engn, Davis, CA 95616 USA..
    Olsson, F.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Lourdudoss, Sebastian
    KTH, Superseded Departments (pre-2005), Microelectronics and Information Technology, IMIT.
    Stephan, P. L.
    Lawrence Livermore Natl Lab, Livermore, CA 94550 USA..
    Error-free spectral encoding and decoding operation of InPO-CDMA encoder2006In: 2006 OPTICAL FIBER COMMUNICATION CONFERENCE/NATIONAL FIBER OPTIC ENGINEERS CONFERENCE, VOLS 1-6, OPTICAL SOC AMERICA , 2006, p. 843-+Conference paper (Refereed)
    Abstract [en]

    We report error-free spectral encoding and decoding operation of an InP monolithic, ultra-compact optical-CDMA encoder/decoder photonic chip pair. The experimental results demonstrate the strong potential for realizing high performance O-CDMA networks with InP micro-systems. (C) 2006 Optical Society of America.

  • 127.
    Cao, Wei Qiu
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    A new Content Distribution Network architecture - PlentyCast2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Content Distribution Networks have existed for some years. They involve the following problem domains and have attracted attention both in academic research and industry: content replica placement, content location and routing, swarm intelligence, and overlay network self-organization for this type of distributed system. In this project, we propose a novel Content Distribution Network architecture – PlentyCast. This study focuses on improving access latency, network scalability, high content availability, low bandwidth consumption, and improving infrastructure performance for Content Distribution Networks. Outstanding problems such as: Flash crowd, DoS, and difficulty of traffic engineering due to Peer-to-Peer are addressed.

  • 128. Carlsson, C.
    et al.
    Barrios, C. A.
    Messmer, E. R.
    Lovqvist, A.
    Halonen, J.
    Vukusic, J.
    Ghisoni, M.
    Lourdudoss, Sebastian
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Larsson, A.
    Performance characteristics of buried heterostructure VCSELs using semi-insulating GaInP: Fe regrowth2001In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 37, no 7, p. 945-950Article in journal (Refereed)
    Abstract [en]

    We have fabricated GaAs-AlGaAs buried heterostructure vertical cavity surface emitting lasers, emitting at 850 nm, using semi-insulating GaInP:Fe regrowth and investigated their static properties. Lasers of different size (10-21 mum) have threshold currents in the range 2.8-7.0 mA, and produce a maximum output power of 1.7-6.0 mW at room temperature. The variation of threshold current with device size shows that the leakage current at the regrowth interface accounts for a significant part of the injection current. In spite of this, a differential quantum efficiency in the range 20%-30% is obtained which indicates that the regrowth interface is smooth and does not introduce any significant scattering loss. Studies of the transverse mode properties suggest that the GaInP provides weak guiding, resulting in single mode operation up to an output power of 0.7 mW and a beam divergence of only 6 degrees for lasers as large as 10 mum.

  • 129. Carlsson, C.
    et al.
    Martinsson, H.
    Schatz, Richard
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Halonen, J.
    Larsson, A.
    Analog modulation properties of oxide confined VCSELs at microwave frequencies2002In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 20, no 9, p. 1740-1749Article in journal (Refereed)
    Abstract [en]

    Motivated by the need for affordable, high-performance fiber-optic microwave links in fiber-fed microcellular networks and radar systems, we have performed a comprehensive experimental evaluation of the microwave modulation characteristics of high-speed oxide-confined vertical cavity surface emitting lasers (VCSELs) emitting at 840 inn. VCSELs with different oxide aperture diameters, including both single- and multimode lasers, have been used to track the dependence on modal behavior. The study includes both static and dynamic characteristics, with an emphasis on those of major importance for analog modulation. This includes the small-signal modulation response (S-11 and S-21), the relative intensity noise (RIN), and the intermodulation distortion. From this, we determine the spurious free dynamic range, the impedance characteristics, and the speed limitations.

  • 130. Carlsson, C.
    et al.
    Modh, P.
    Halonen, J.
    Schatz, Richard
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Larsson, A.
    High-frequency analog modulation of oxide confined 670-nm vertical-cavity surface-emitting lasers2004In: Optical Engineering: The Journal of SPIE, ISSN 0091-3286, E-ISSN 1560-2303, Vol. 43, no 12, p. 3138-3141Article in journal (Refereed)
    Abstract [en]

    We investigate the bandwidth limitations and the analog modulation characteristics at microwave frequencies (0.1 to 10 GHz)of a low-capacitance oxide-confined 670-nm InGaAIP vertical-cavity surface-emitting laser (VCSEL). A maximum modulation bandwidth of 6.3 GHz, limited by thermal effects, is achieved. From measurements of distortion and noise, a spurious free dynamic range (SFDR) of 100 dB Hz(2/3) is obtained at frequencies up to 2 GHz, rendering such VCSELs useful for transmission of analog signals. At higher frequencies, the SFDR drops due to the thermally limited resonance frequency.

  • 131.
    Carlström, Carl-Fredrik
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ion beam etching of InP based materials2001Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Dry etching is an important technique for pattern transferin fabrication of most opto-electronic devices, since it canprovide good control of both structure size and shape even on asub-micron scale. Unfortunately, this process step may causedamage to the material which is detrimental to deviceperformance. It is therefore an objective of this thesis todevelop and investigate low damage etching processes for InPbased devices.

    An ion beam system in combination with hydrocarbon (CH4) based chemistries is used for etching. At variousion energies and gas flows the etching is performed in twomodes, reactive ion beam etching (RIBE) and chemical assistedion beam etching (CAIBE). How these conditions affect both etchcharacteristics (e.g. etch rates and profiles, surfacemorphology and polymer formation) and etch induced damage (onoptical and electrical properties) is evaluated and discussed.Attention is also paid to the effects of typical post etchingtreatments such as annealing on the optical and electricalproperties. An important finding is the correlation betweenas-etched surface morphology and recovery/degradation inphotoluminescence upon annealing in PH3. Since this type of atmosphere is typical forcrystal regrowth (an important process step in III/Vprocessing) a positive result is imperative. A low ion energy N2/CH4/H2CAIBE process is developed which not onlysatisfies this criteria but also exhibits good etchcharacteristics. This process is used successfully in thefabrication of laser gratings. In addition to this, the abilityof the ion beam system to modify the surface morphology in acontrollable manner is exploited. By exposing such modifiedsurfaces to AsH3/PH3, a new way to vary size and density of InAs(P)islands formed on the InP surfaces by the As/P exchangereaction is presented.

    This thesis also proposes a new etch chemistry, namelytrimethylamine ((CH3)3N or TMA), which is a more efficient methyl sourcecompared to CH4because of the low energy required to break the H3C-N bond. Since methyl radicals are needed for theetching it is presumably a better etching chemistry. A similarinvestigation as for the CH4chemistry is performed, and it is found that bothin terms of etch characteristics and etch induced damage thisnew chemistry is superior. Extremely smooth morphologies, lowetch induced damage and an almost complete recovery uponannealing can be obtained with this process. Significantly,this is also so at relatively high ion energies which allowshigher etch rates.

    Keywords:InP, dry etching, ion beam etching, RIBE,CAIBE, hydrocarbon chemistry, trimethylamine, As/P exchangereaction, morpholoy, low damage, AFM, SCM, annealing

  • 132. Carmody, C.
    et al.
    Tan, H. H.
    Jagadish, C.
    Douhéret, Olivier
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Maknys, Kestutis
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Anand, Srinivasan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zou, J.
    Dao, L.
    Gal, M.
    Structural, electrical, and optical analysis of ion implanted semi-insulating InP2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 95, no 2, p. 477-482Article in journal (Refereed)
    Abstract [en]

    Semi-insulating InP was implanted with MeV P, As, Ga, and In ions, and the resulting evolution of structural properties with increased annealing temperature was analyzed using double crystal x-ray diffractometry and cross sectional transmission electron microscopy. The types of damage identified are correlated with scanning spreading resistance and scanning capacitance measurements, as well as with previously measured Hall effect and time resolved photoluminescence results. We have identified multiple layers of conductivity in the samples which occur due to the nonuniform damage profile of a single implant. Our structural studies have shown that the amount and type of damage caused by implantation does not scale with implant ion atomic mass.

  • 133. Carmody, C.
    et al.
    Tan, H. H.
    Jagadish, C.
    Gaarder, A.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ion-implanted In0.53Ga0.47As for ultrafast optoelectronic applications2003In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 82, no 22, p. 3913-3915Article in journal (Refereed)
    Abstract [en]

    Undoped In0.53Ga0.47As epilayers were implanted with 2- MeV Fe+ ions at doses of 1x10(15) and 1x10(16) cm(-2) at room temperature and annealed at temperatures between 500 and 800 degreesC. Hall-effect measurements show that after annealing, layers with resistivities on the order of 10(5) Omega/square can be achieved. Carrier lifetimes as short as 300 fs are observed for samples annealed at 500 and 600 degreesC. For higher annealing temperatures, characteristic times of the optical response are on the order of a few picoseconds.

  • 134. Carmody, C.
    et al.
    Tan, H. H.
    Jagadish, C.
    Gaarder, A.
    Marcinkevicius, Saulius
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Ultrafast carrier trapping and recombination in highly resistive ion implanted InP2003In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 94, no 2, p. 1074-1078Article in journal (Refereed)
    Abstract [en]

    MeV P+ implanted and annealed p-InP, and Fe+ implanted and annealed semi-insulating InP have both been shown to produce the high resistivity, good mobility, and ultrafast optical response desired for ultrafast photodetectors. Hall effect measurements and time resolved photoluminescence were used to analyze the electrical and optical features of such implanted materials. Low temperature annealing was found to yield the fastest response times-130 fs for Fe+ implanted and 400 fs for P+ implanted InP, as well as resistivities of the order similar to10(6) Omega/square. It was found that the electrical activation of Fe-related centers, useful for achieving high resistivities in Fe+ implanted semi-insulating InP, was not fully realized at the annealing temperatures chosen to produce the fastest optical response. Implanting p-InP in the dose regime where type conversion occurs, and subsequent annealing at 500degreesC, produces high resistivities and ultrafast carrier trapping times that are only marginally dose dependent.

  • 135. Carney, P. S.
    et al.
    Fischer, D. G.
    Foley, J. T.
    Friberg, Ari T.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Shchegrov, A. V.
    Visser, T. D.
    Wolf, E.
    Comment - Evanescent waves do contribute to the far field2000In: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 47, no 4, p. 757-758Article in journal (Refereed)
  • 136. Cerf, N. J.
    et al.
    Bourennane, M.
    Karlsson, Anders
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Gisin, N.
    Security of quantum key distribution using d-level systems2002In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 88, no 12Article in journal (Refereed)
    Abstract [en]

    We consider two quantum cryptographic schemes relying on encoding the key into qudits, i.e., quantum states in a d-dimensional Hilbert space. The first cryptosystem uses two mutually unbiased bases (thereby extending the BB84 scheme), while the second exploits all d + 1 available such bases (extending the six-state protocol for qubits). We derive the information gained by a potential eavesdropper applying a cloning-based individual attack, along with an upper bound on the error rate that ensures unconditional security against coherent attacks.

  • 137.
    Chacinski, Marek
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Kjebon, Olle
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Detuned-loading effects on directly-modulated high-speed lasers2004In: 2004 International Students and Young Scientists Workshop Photonics and Microsystems, Proceedings / [ed] Dylewicz, R; Patela, S, NEW YORK: IEEE , 2004, p. 7-7Conference paper (Refereed)
    Abstract [en]

    The modulation bandwidth and linewidth enhancement factor were investigated and found to be strongly dependent on the position of the lasing mode on the Bragg reflection peak.

  • 138.
    Chacinski, Marek
    et al.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Schatz, Richard
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Kjebon, Olle
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Directly modulated lasers detuned loading effect2004In: 2004 International Students and Young Scientists Workshop - Photonics and Microsystems, 2004, p. 1-21Conference paper (Refereed)
  • 139. Chakraborty, M.
    et al.
    Misra, I. S.
    Saha, D.
    Mukherjee, Amitava
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    A novel fast handover technique for TLMM: Three Level Mobility Model for next generation wireless iP-based networks2004In: PROCEEDINGS OF THE IEEE INDICON 2004, 2004, p. 327-332Conference paper (Refereed)
    Abstract [en]

    This paper proposes a fast and seamless handover management scheme for the Three Level Mobility Model (TLMM) network. TLMM mobility may be more enhanced by using Fast Handover for MIPv6 (FMIPv6). The paper modifies and extends the FMIPv6 with bi-casting functions to minimize packet loss at the mobile node.

  • 140. Chakraborty, M.
    et al.
    Misra, I. S.
    Saha, D.
    Mukherjee, Amitava
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    QoS support in TLMM: Three level mobility model for IP-based networks2004In: DISTRIBUTED COMPUTING: IWDC 2004, PROCEEDINGS, 2004, p. 192-197Conference paper (Refereed)
    Abstract [en]

    TLMM, a three level mobility model for IP-based mobility management has been recently proposed as an architecture for managing global mobility in an IP-based network. This paper evaluates the performance of TLMM's Quality of Service (QoS) framework using a combination of DiffServ and Int-Serv architectures with the concept of Bandwidth Broker for admission control and resource reservation for different service classes. The most important contribution in this paper is a dynamic handoff policy using the concept of Boundary Location Area, for performing location updates for inter-domain roaming of mobile nodes, which helps in maintaining proper QoS. The performance evaluation of the proposed protocol is provided by simulation results using Network Simulator (ns-2).

  • 141. Chen, C. C.
    et al.
    Lindgren, A. C.
    Zhang, Shi-Li
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zhu, D. Z.
    Vantomme, A.
    Different strain relaxation mechanisms in strained Si/Si1-xGex/Si heterostructures by high dose B+ and BF2+ doping2002In: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 198, no 02-jan, p. 57-63Article in journal (Refereed)
    Abstract [en]

    Strained Si/Si0.8Ge0.2/Si heterostructures are implanted at room temperature with 7.5 keV B+ and 33 keV BF2+ ions to a high dose of 2 x 10(15) ions/cm(2), respectively. The samples are subsequently subjected to three-step anneals (spacer anneal, oxidation anneal and rapid thermal anneal), which are used to simulate a real fabrication process of SiGe-based MOSFET devices. The damage induced by implantation and its recovery are characterized by 2 MeV He-4(+) RBS/ channeling spectrometry. A damage layer on the surface is induced by B+ implantation, but BF2+ ion implantation amorphizes the surface of Si/Si0.8Ge0.2/Si heterostructure. Channeling angular scans along the (110) axial direction demonstrate that the strain stored in the SiGe layer could be nearly completely retained for the B+ implantated and subsequently annealed sample. However, the strain in the BF2+ implanted/annealed SiGe layer has decreased drastically.

  • 142.
    Chen, Chuansu
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Resuable macro based synthesis for digital ASIC design2002Licentiate thesis, comprehensive summary (Other scientific)
  • 143. Chen, L.
    et al.
    Duo, Xingzhong
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Zheng, Lirong
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Lai, Z.
    Liu, J.
    Process development and reliability for system-in-a-package using liquid crystal polymer substrate2004In: Proc Electron Compon Technol Conf, 2004, p. 24-28Conference paper (Refereed)
    Abstract [en]

    In this study, embedded chip technology for system-in-a-package (SiP) application using liquid crystal polymer (LCP) substrate was developed and the reliability issue for embedded structure was evaluated. To this end two test chips with daisy chain joints were used with one copper layer. After assembly, modules were exposed to thermal cycling. The failure was investigated by SEM, and compared with finite element method (FEM) simulation results. Passive components as inductors were also fabricated on the LCP during the embedded technology. Their inductance and quality factors were simulated and discussed.

  • 144.
    Chitica, Nicolae
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Surface-Micromachined Vertical-Cavity Micro-Opto-Electro-Mechanical Devices on InP2003Doctoral thesis, comprehensive summary (Other scientific)
  • 145. Cho, C. R.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Thickness dependent performance of Na0.5K0.5NbO3/sapphire thin film varactors2001In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 39, no 1-4, p. 1353-1360Article in journal (Refereed)
    Abstract [en]

    Perfect c-axis oriented Na0.5K0.5NbO3 (NKN) films have been pulsed laser deposited on Al2O3(01 (1) under bar2) single crystals (r-cut sapphire) for voltage tunable microwave device applications. Thickness dependence of dielectric performance of the NKN/sapphire interdigital capacitors (IDCs) has been studied. 40 V bias tunability and dielectric loss tandelta of 4 burr slot IDCs have been found to be 24.6 % and 2.86 % for 1.2 mum thick NKN film, and 6.1 % and 0.83 % for 0.14 mum thick NKN film, respectively. Low leakage currents and high breakdown voltages are observed in these structures.

  • 146. Cho, C. R.
    et al.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Moon, B. M.
    Ferroelectric Na0.5K0.5NbO3 thin films by pulsed laser deposition2000In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 31, no 1-4, p. 35-45Article in journal (Refereed)
    Abstract [en]

    Highly c-axis oriented single phase Na0.5K0.5NbO3 (NKN) thin films have been deposited onto polycrystalline Pt80Ir20 substrates and SiO2/Si(001) wafers using pulsed laser ablation of stoichiometric ceramic target. Strong self-assembling of NKN films along the [001] direction has been observed. Properties of NKN/Pt thin film structures have been successfully tailored by oxygen pressure control from the ferroelectric state, characterized by the remnant polarization of 12 muC/cm(2), dielectric constant epsilon similar to 520 and tan delta - 0.024 @ 100 kHz, to superparaelectric state with tan delta as low as 0.003 and epsilon = 210 with very small 1.7% dispersion in the frequency domain 0.4-100 kHz and less than 10% Variation in the temperature range 77-415 K. NKN films grown onto SiO2/Si(001) substrates show quadrupled super-lattice structure along c-axis, loss tan delta less than 0.01, and epsilon similar to 110 @ 1 MHz. C-V measure ments for Au/NKN(270nm)/SiO2/Si MFIS-diode structure yield memory window of 3.26 V at the programmable voltage of 8 V.

  • 147. Cho, C. R.
    et al.
    Koh, J. H.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Abadei, S.
    Gevorgian, S.
    Na0.5K0.5NbO3/SiO2/Si thin film varactor2000In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 76, no 13, p. 1761-1763Article in journal (Refereed)
    Abstract [en]

    Perfectly c-axis oriented micrometer thick Na0.5K0.5NbO3(NKN) films have been prepared on a thermally grown ultrathin SiO2 template layer onto a Si(001) wafer by the pulsed laser deposition technique. A x-ray diffraction theta-2 theta scan reveals multiple-cell structuring of single phase NKN film along the polar axis, while films grown onto amorphous ceramic (Corning) glass show a mixture of slightly c-axis oriented NKN and pyrochlore phases. This implies a small amount of SiO2 crystallites distributed in an amorphous matrix inherit Si(001) orientation and promotes highly oriented NKN film growth. NKN film dielectric permittivity epsilon' was found to vary from 114.0 to 107.2 in the frequency range 1 kHz-1 MHz, while the resistivity was on the order of 2.6 x 10(10) Ohm cm @ 20 kV/cm. The planar interdigital variable reactance device (varactor) based on the NKN/SiO2/Si thin film structure possesses a dissipation factor of 0.8% at 1 MHz and zero bias, electrical tunability of 3.1%, and nA order leakage current at 20 V bias at room temperature.

  • 148. Cho, C. R.
    et al.
    Park, S. H.
    Moon, B. M.
    Sundqvist, J.
    Harsta, A.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Na0.5K0.5NbO3 thin films for MFIS_FET type non-volatile memory applications2002In: Integrated Ferroelectrics, ISSN 1058-4587, E-ISSN 1607-8489, Vol. 49, p. 21-30Article in journal (Refereed)
    Abstract [en]

    Na0.5K0.5NbO3(NKN) thin films have been prepared on Pt80Ir20, SiO2/Si, and Ta2O5/Si substrates for ferroelectric non-volatile memory applications. Ferroelectric hysteresis loops for Au/NKN/Pt80Ir20 vertical capacitor yielded remnant polarization of 12 muC/cm(2) and coercive field similar to20 kV/cm. Significant flat-band voltage V-FB shifts with buffer layer thickness in Au/NKN/SiO2/Si structures have been attributed to the intermixing between Na and K alkali ions and SiO2 layer. On the other hand, Au/NKN/Ta2O5/Si structure exhibited wide memory window without significant V-FB deviations, low leakage currents, and rather long retention time at zero bias.

  • 149.
    Cho, Choong-Rae
    et al.
    Department of Solid State Electronics, Ångström Laboratory, Uppsala University.
    Katardjiev, Ilia
    Department of Solid State Electronics, Ångström Laboratory, Uppsala University.
    Grishin, Michael A.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Na0.5K0.5NbO3 thin films for voltage controlled acoustoelectric device applications2002In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 80, no 17, p. 3171-3173Article in journal (Refereed)
    Abstract [en]

    Perovskite Na0.5K0.5NbO3 (NKN) thin films have been prepared on Y+36degrees cut single crystal quartz substrates using the pulsed laser ablation technique. X-ray diffraction theta-2theta and omega-scan data demonstrate almost perfectly c-axis oriented film textures with narrow mosaic broadening. Radio frequency dielectric spectroscopy showed that the films possess relatively high dielectric permittivities, low dielectric losses, and low frequency dispersions. Capacitance-voltage (C-V) measurements for a 2 mum slot NKN/quartz interdigital capacitor yield 23.1% tunability by applying 40 V bias at 1 MHz, while C-V hysteresis indicates polarization reversal. The considerable voltage tunability with superior crystallinity in piezoelectric NKN films on quartz substrates suggests their potential use for novel voltage tunable acoustoelectric devices.

  • 150. Cho, H.
    et al.
    Lee, K. P.
    Leerungnawarat, P.
    Chu, S. N. G.
    Ren, F.
    Pearton, S. J.
    Zetterling, Carl-Mikael
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    High density plasma via hole etching in SiC2001In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 19, no 4, p. 1878-1881Article in journal (Refereed)
    Abstract [en]

    Throughwafer vias up to 100 mum deep were formed in 4H-SiC substrates by inductively coupled plasma etching with SF6/O-2 at a controlled rate of similar to0.6 mum min(-1) and use of Al masks. Selectivities of > 50 for SiC over Al were achieved. Electrical (capacitance-voltage: current-voltage) and chemical (Auger electron spectroscopy) analysis techniques showed that the etching produced only minor changes in reverse breakdown voltage, Schottky barrier height, and near surface stoichiometry of the SiC and had high selectivity over common frontside metallization. The SiC etch rate was a strong function of the incident ion energy during plasma exposure. This process is attractive for power SiC transistors intended for high current, high temperature applications and also for SiC micromachining.

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