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  • 251.
    Johansson, Ted
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Norstrom, H.
    Smith, U.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Influence of SOI-generated stress on BiCMOS performance2005Inngår i: Semiconductor Device Research Symposium, 2005 International, 2005, s. 444-445Konferansepaper (Fagfellevurdert)
  • 252.
    Junesand, Carl
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Olsson, Fredrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Xiang, Yu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Gau, Ming-Horng
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Heterogeneous integration of indium phosphide on silicon by nano-epitaxial lateral overgrowth2009Inngår i: 2009 IEEE 21ST INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM), 2009, s. 59-62Konferansepaper (Fagfellevurdert)
    Abstract [en]

    InP on Si is grown by nano-epitaxial lateral overgrowth (nano-ELOG) on patterns consisting of net-type openings under different growth conditions. Analysis shows that net-type patterns yield large lateral growth rate and good optical quality. Different growth conditions have a substantial impact on growth rate and some effect on surface morphology, as well as on the optical quality. Optical quality is deemed to be affected partly by the amount of dislocations arising from the difference in thermal expansion coefficient between the mask and the InP layer, and partly by the layer thickness and surface morphology.

  • 253.
    Junesand, Carl
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Olsson, Fredrik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Xiang, Yu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Gau, Ming-Horng
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Surface morphology of indium phosphide grown on silicon by nano-epitaxial lateral overgrowth2009Inngår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 6, nr 12, s. 2785-2788Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    InP is grown on Si by nano-epitaxial lateral overgrowth (NELOG or nano-ELOG) on patterns consisting of net-type openings under different growth conditions. Surface morphology is characterized with AFM and profilometer and optical quality assessed by Micro Photoluminescence measurements (mu-PL). Results show that growth conditions affect both morphology and optical quality, with thicker layers generally corresponding to better surface morphology. Lower growth temperature seems to improve surface morphology irrespective of thickness, and ELOG layers exhibit significantly better morphology than the planar layer.

  • 254. Kaiser, M.
    et al.
    Hupfer, T.
    Jokubavicus, V.
    Schimmel, S.
    Syväjärvi, M.
    Ou, Y.
    Ou, H.
    Linnarsson, Margareta K.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Wellmann, P.
    Polycrystalline SiC as source material for the growth of fluorescent SiC layers2013Inngår i: Silicon Carbide And Related Materials 2012, Trans Tech Publications Inc., 2013, Vol. 740-742, s. 39-42Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Polycrystalline doped SiC act as source for fluorescent SiC. We have studied the growth of individual grains with different polytypes in the source material. We show an evolution and orientation of grains of different polytypes in polycrystalline SiC ingots grown by the Physical Vapor Transport method. The grain influence on the growth rate of fluorescent SiC layers grown by a sublimation epitaxial process is discussed in respect of surface kinetics.

  • 255. Kaiser, M.
    et al.
    Schimmel, S.
    Jokubavicius, V.
    Linnarsson, Margareta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ou, H.
    Syväjärvi, M.
    Wellmann, P.
    Nucleation and growth of polycrystalline SiC2014Inngår i: IOP Conference Series: Materials Science and Engineering, 2014, nr 1Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The nucleation and bulk growth of polycrystalline SiC in a 2 inch PVT setup using isostatic and pyrolytic graphite as substrates was studied. Textured nucleation occurs under near-thermal equilibrium conditions at the initial growth stage with hexagonal platelet shaped crystallites of 4H, 6H and 15R polytypes. It is found that pyrolytic graphite results in enhanced texturing of the nucleating gas species. Reducing the pressure leads to growth of the crystallites until a closed polycrystalline SiC layer containing voids with a rough surface is developed. Bulk growth was conducted at 35 mbar Ar pressure at 2250°C in diffusion limited mass transport regime generating a convex shaped growth form of the solid-gas interface leading to lateral expansion of virtually [001] oriented crystallites. Growth at 2350°C led to the stabilization of 6H polytypic grains. The micropipe density in the bulk strongly depends on the substrate used.

  • 256. Kang, M. -S
    et al.
    Lee, J. -H
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Bahng, W.
    Kim, N. -K
    Koo, S. -M
    Metal work-function and doping-concentration dependent barrier height of Ni-contacts to 4H-SiC with metal-embedded nano-particles2012Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 717-720, s. 857-860Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated the effect of the metal work-function and doping concentration on the barrier height of Ni-contacts with embedded nano-particles (NPs) on 4H-SiC surfaces. Both n-type epitaxial layers with N-D=1x10(16) cm(-3), and layers doped by phosphorus implantation to a doping concentration of similar to 1x10(19) cm(-3) are used. The barrier height is reduced with increasing doping concentration and the silver (Ag) nano-particles (R similar to 18.5 nm) further enhance the local electric field of the electrical contacts to 4H-SiC in comparison to gold (Au) nano-particles (R similar to 20.2 nm). In the case of ion-implanted samples, the barrier height of the fabricated SiC diode structures with embedded Ag-NPs was significantly reduced by similar to 0.09 eV and similar to 0.25 eV compared to the samples with Au-NPs and the sample without NPs, respectively.

  • 257. Kang, Min-Seok
    et al.
    Lee, Jung-Ho
    Hallen, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Koo, Sang-Mo
    Effect of annealing temperature on the barrier height of nano-particle embedded Ni-contacts to 4H-SiC2011Inngår i: 2011 International Semiconductor Device Research Symposium (ISDRS), 2011, s. 1-2Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In order to realize stable SiC (Silicon carbide) devices, metal contacts to SiC with suitable physical and electrical characteristics are required. For example, Ohmic contacts with low specific contact resistances and Schottky contacts with controlled barrier height ( #x03A6;B) between SiC and metal are among the most important factors for determining the performance of SiC devices. To date, extensive studies have been carried out on the properties of barrier height of various metals on n- and p-type for SiC and many attempts have been made to modify the contact barrier height on SiC depending on the annealing temperature. To change effectively lower the barrier height of the metal/SiC structures, it was required to anneal the contact formed on highly doped 4H-SiC substrates ( #x003E;1018 cm #x2212;3) at high temperatures (900 #x223C;1000 #x00B0;C) [1]. Recently, the electrical contacts to SiC includes the implementation of nanostructures such as metal nano-partices (NPs) to modify the barrier height at metal-SiC interfaces and to alter fundamental SiC device properties by controlling the size of the metal NPs [2]. Previous results in the literature have been primarily focused on the effect of size reduction of NPs on the characteristics of diode structures with embedded NPs, which experimentally investigates the change in transport properties of metal/semiconductor interfaces in SiC depending on the size of NPs. However, so far the focus has been mainly on the scaling effect of NPs rather than on altering the electrical barrier of the NPs [3].

  • 258.
    Kargarrazi, Saleh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Bipolar Silicon Carbide Integrated Circuits for High Temperature Power Applications2014Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Silicon Carbide (SiC) is suggested as a superior material for high temperature and high power electronic applications, thanks to its excellent properties. In this thesis, design and measurements of integrated circuits in bipolar 4H-SiC aiming for high temperature power applications are reported. On the low power side, a linear voltage regulator is demonstrated followed by introduction of a general-purpose opamp, which is employed to build other circuits such as a Schmitt trigger and a relaxation oscillator. On the high power side, a monolithic drive circuit for power BJTs is designed and tested in different loading conditions including resistive, capacitive and finally together with a commercial power BJT. The aforementioned circuits have been tested in the temperature range 25 - 500 °C, and are operational in the full range. The performance of each circuit is analyzed and directions for future work is suggested. The integrated circuits of this thesis set the reference for future advances in power integrated circuits in bipolar SiC.

  • 259.
    Kargarrazi, Saleh
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lanni, Luigia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A monolithic SiC drive circuit for SiC Power BJTs2015Inngår i: 2015 IEEE 27TH INTERNATIONAL SYMPOSIUM ON POWER SEMICONDUCTOR DEVICES & IC'S (ISPSD), IEEE , 2015, s. 285-288Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Silicon Carbide (SiC) is an excellent candidate for high temperature electronics applications, thanks to its wide bandgap. SiC power BJTs are commercially available nowadays, and it is demanding to drive them efficiently. This paper reports on the design, layout specifics, and measurements results of a SiC drive integrated circuit (IC) designed for driving SiC power BJTs. The circuit has been tested in different loading conditions (resistive and capacitive), at switching frequencies up to 500kHz, and together with a commercial power BJT. The SiC drive IC is shown to have a robust operation over the entire temperature range from 25 degrees C to 500 degrees C.

  • 260.
    Kargarrazi, Saleh
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lanni, Luigia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Saggini, Stefano
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    500 degrees C Bipolar SiC Linear Voltage Regulator2015Inngår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 62, nr 6, s. 1953-1957Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, we demonstrate a fully integrated linear voltage regulator in silicon carbide NPN bipolar transistor technology, operational from 25 degrees C up to 500 degrees C. For 15-mA load current, this regulator provides a stable output voltage with <2% variation in the temperature range 25 degrees C-500 degrees C. For both line and load regulations, degradation of 50% from 25 degrees C to 300 degrees C and improvement of 50% from 300 degrees C to 500 degrees C are observed. The transient response measurements of the regulator show robust behavior in the temperature range 25 degrees C-500 degrees C.

  • 261.
    Kargarrazi, Saleh
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lanni, Luigia
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A study on positive-feedback configuration of a bipolar SiC high temperature operational amplifier2016Inngår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 116, s. 33-37Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports on the design and implementation of an integrated operational amplifier in bipolar SiC, and elaborates on its operation in positive-feedback configuration. The opamp is studied in different feedback setups: closed-loop compensated amplifier, comparator with hysteresis (Schmitt trigger), and as a relaxation oscillator. Measurement results suggest a stable closed-loop opamp with similar to 40 dB gain, a Schmitt trigger with constant threshold levels over a wide temperature range, and a relaxation oscillator tested up to 540 kHz. All the setups were tested from 25 degrees C up to 500 degrees C.

  • 262.
    Kargarrazi, Saleh
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lanni, Luigia
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Design and characterization of 500°c schmitt trigger in 4H-SiC2015Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 821-823, s. 897-901Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two versions of Schmitt trigger, an emitter-coupled and an operational amplifier (opamp)-based, are implemented in 4H-SiC bipolar technology and tested up to 500 °C. The former benefits the simplicity, smaller footprint, and fewer number of devices, whereas the latter provides better promise for high temperature applications, thanks to its more stable temperature characteristics. In addition, the measurements in the range 25 °C - 500 °C, shows that the opamp-based version provides negative and positive slew rates of 4.8 V/μs and 8.3 V/μs, ~8 and ~3 times higher than that of the emitter-coupled version, which are 1.7 V/μs and 1 V/μs.

  • 263. Karim, A.
    et al.
    Gustafsson, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Savage, S.
    Wang, Q.
    Almqvist, S.
    Asplund, C.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Jan, Y. A.
    In(Ga)Sb/InAs quantum dot based IR photodetectors with thermally activated photoresponse2013Inngår i: Proceedings of SPIE 8704, Infrared Technology and Applications XXXIX, SPIE - International Society for Optical Engineering, 2013, s. 870434-Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We report on the device characterization of In(Ga)Sb/InAs quantum dots (QDs) based photodetectors for long wave IR detectors. The detection principle of these quantum-dot infrared photodetectors (QDIPs) is based on the spatially indirect transition between the In(Ga)Sb QDs and the InAs matrix, as a result of the type-II band alignment. Such photodetectors are expected to have lower dark currents and higher operating temperatures compared to the current state of the art InSb and mercury cadmium telluride (MCT) technology. The In(Ga)Sb QD structures were grown using metal-organic vapour-phase epitaxy and explored using structural, electrical and optical characterization techniques. Material development resulted in obtaining photoluminescence up to 10 μm, which is the longest wavelength reported in this material system. We have fabricated different photovoltaic IR detectors from the developed material that show absorption up to 8 μm. Photoresponse spectra, showing In(Ga)Sb QD related absorption edge, were obtained up to 200 K. Detectors with different In(Ga)Sb QDs showing different cut-off wavelengths were investigated for photoresponse. Photoresponse in these detectors is thermally activated with different activation energies for devices with different cut-off wavelengths. Devices with longer cut-off wavelength exhibit higher activation energies. We can interpret this using the energy band diagram of the dots/matrix system for different QD sizes.

  • 264.
    Karim, Amir
    et al.
    Acreo.
    Gustafsson, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hussain, Liaq
    Acrero.
    Wang, Q.
    Noharet, B.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Anderson, J.
    Song, J.
    Characterization of InSb QDs grown on InAs (100) substrate by MBE and MOVPE2012Inngår i: Proc SPIE Int Soc Opt Eng, 2012Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We report on the optical and structural characterization of InSb QDs in InAs matrix, grown on InAs (100) substrates, for infrared photodetection. InSb has 7% lattice mismatch with InAs forming strained QDs, which are promising for longwave IR applications, due to their type-II band alignment. This report contains material development results of InSb QDs for increasing their emission wavelength towards long-wave IR region. Samples were grown by two techniques of MBE and MOVPE, with different InSb coverage on InAs (100) substrates. Structures grown by MBE reveal QD related photoluminescence at 4 μm. AFM investigations of the MBE grown structures showed uncapped dots of ∼ 35 nm in size and ∼ 3 nm in height, with a density of about 2 × 1010 cm -2. Cross-section TEM investigations of buried InSb layers grown by MBE showed coherently strained QDs for nominal InSb coverage in the range of 1.6 - 2 monolayers (MLs). Layers with InSb coverage more than 2MLs contain relaxed QDs with structural defects due to large amount of strain between InSb and InAs. Samples with such large dots did not show any InSb related luminescence. The MOVPE grown InSb samples exhibit a strong QD related emission between 3.8 to 7.5 μm, depending on the amount of InSb coverage and other growth parameters. We report the longest wavelength observed so far in this material system.

  • 265. Karlsson, L. H.
    et al.
    Hallen, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Birch, J.
    Hultman, L.
    Persson, P. O. A.
    Atomically resolved microscopy of ion implantation induced dislocation loops in 4H-SiC2016Inngår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 181, s. 325-327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During high temperature electrical activation of ion-implanted dopant species in SiC, extrinsic dislocation loops are formed on the basal planes of the SiC lattice. Investigations have suggested Si-based loops are caused in accordance with the well-known +1 model. Herein we apply aberration corrected STEM to resolve the atomic structure of these loops. It is shown that the dislocation loops formed during annealing of Al-implanted SiC consist of an extra inserted Si-C bilayer of the (0001) polar sense, which upon insertion into the lattice causes a local extrinsic stacking fault. The +1 model thus needs to be expanded for binary systems. (C) 2016 Elsevier B.V. All rights reserved.

  • 266. Kataria, S.
    et al.
    Wagner, S.
    Ruhkopf, J.
    Gahoi, A.
    Pandey, H.
    Bornemann, R.
    Vaziri, Sam
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lemme, Max C.
    Univ Siegen, Germany.
    Chemical vapor deposited graphene: From synthesis to applications2014Inngår i: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 211, nr 11, s. 2439-2449Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Graphene is a material with enormous potential for numerous applications. Therefore, significant efforts are dedicated to large-scale graphene production using a chemical vapor deposition (CVD) technique. In addition, research is directed at developing methods to incorporate graphene in established production technologies and process flows. In this paper, we present a brief review of available CVD methods for graphene synthesis. We also discuss scalable methods to transfer graphene onto desired substrates. Finally, we discuss potential applications that would benefit from a fully scaled, semiconductor technology compatible production process.

  • 267.
    Katic, Janko
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Efficient Energy Harvesting Interface for Implantable Biosensors2015Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    Energy harvesting is identified as a promising alternative solution for powering implantable biosensors. It can completely replace the batteries, which are introducing many limitations, and it enables the development of self-powered implantable biosensors. An interface circuit is necessary to correct for differences in the voltage and power levels provided by an energy harvesting device from one side, and required by biosensor circuits from another. This thesis investigates the available energy harvesting sources within the human body, selects the most suitable one and proposes the power management unit (PMU), which serves as an interface between a harvester and biosensor circuits. The PMU targets the efficient power transfer from the selected source to the implantable biosensor circuits.

    Based on the investigation of potential energy harvesting sources, a thermoelectric energy harvester is selected. It can provide relatively high power density of 100 μW/cm2 at very low temperature difference available in the human body. Additionally, a thermoelectric energy harvester is miniature, biocompatible, and it has an unlimited lifetime.

    A power management system architecture for thermoelectric energy harvesters is proposed. The input converter, which is the critical block of the PMU, is implemented as a boost converter with an external inductor. A detailed analysis of all potential losses within the boost converter is conducted to estimate their influence on the conversion efficiency. The analysis showed that the inevitable conduction and switching losses can be reduced by the proper sizing of the converter’s switches and that the synchronization losses can be almost completely eliminated by an efficient control circuit. Additionally, usually neglected dead time losses are proved to have a significant impact in implantable applications, in which they can reduce the efficiency with more than 2%.

    An ultra low power control circuit for the boost converter is proposed. The control is utilizing zero-current switching (ZCS) and zero-voltage switching (ZVS) techniques to eliminate the synchronization losses and enhance the efficiency of the boost converter. The control circuit consumes an average power of only 620 nW. The boost converter driven by the proposed control achieves the peak efficiency higher than 80% and can operate with harvested power below 5 μW. For high voltage conversion ratios, the proposed boost converter/control combination demonstrates significant efficiency improvement compared to state-of-the-art solutions.

  • 268.
    Katic, Janko
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Highly-Efficient Energy Harvesting Interfaces for Implantable Biosensors2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Energy harvesting is identified as an alternative solution for powering implantable biosensors. It can potentially enable the development of self-powered implants if the harvested energy is properly handled. This development implies that batteries, which impose many limitations, are replaced by miniature harvesting devices. Customized interface circuits are necessary to correct for differences in the voltage and power levels provided by harvesting devices from one side, and required by biosensor circuits from another. This thesis investigates the available harvesting sources within the human body, proposes various methods and techniques for designing power-efficient interfaces, and presents two CMOS implementations of such interfaces.

    Based on the investigation of suitable sources, this thesis focuses on glucose biofuel cells and thermoelectric harvesters, which provide appropriate performance in terms of power density and lifetime. In order to maximize the efficiency of the power transfer, this thesis undertakes the following steps. First, it performs a detailed analysis of all potential losses within the converter. Second, in relation to the performed analysis, it proposes a design methodology that aims to minimize the sum of losses and the power consumption of the control circuit. Finally, it presents multiple design techniques to further improve the overall efficiency.

    The combination of the proposed methods and techniques are validated by two highly efficient energy harvesting interfaces. The first implementation, a thermoelectric energy harvesting interface, is based on a single-inductor dual-output boost converter. The measurement results show that it achieves a peak efficiency of 86.6% at 30 μW. The second implementation combines the energy from two sources, glucose biofuel cell and thermoelectric harvester, to accomplish reliable multi-source harvesting. The measurements show that it achieves a peak efficiency of 89.5% when the combined input power is 66 μW. 

  • 269.
    Katic, Janko
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rodriguez, Saul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A Dual-Output Thermoelectric Energy Harvesting Interface with 86.6% Peak Efficiency at 30 μW and Total Control Power of 160 nW2016Inngår i: IEEE Journal of Solid-State Circuits, ISSN 0018-9200, E-ISSN 1558-173XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A thermoelectric energy harvesting interface based on a single-inductor dual-output (SIDO) boost converter is presented. A system-level design methodology combined with ultra-low power circuit techniques reduce the power consumption and minimize the losses within the converter. Additionally, accurate zero-current switching (ZCS) and zero-voltage switching (ZVS) techniques are employed in the control circuit to ensure high conversion efficiency at μW input power levels. The proposed SIDO boost converter is implemented in a 0.18 μm CMOS process and can operate from input voltages as low as 15 mV. The measurement results show that the converter achieves a peak conversion efficiency of 86.6% at 30 μW input power.

  • 270.
    Katic, Janko
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rodriguez, Saul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik, Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    A High-Efficiency Energy Harvesting Interface for Implanted Biofuel Cell and Thermal Harvesters2017Inngår i: IEEE transactions on power electronics, ISSN 0885-8993, E-ISSN 1941-0107, Vol. 33, nr 5, s. 4125-4134, artikkel-id 7940053Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A dual-source energy harvesting interface that combines energy from implanted glucose biofuel cell and thermoelectric generator is presented. A single-inductor dual-input dual-output boost converter topology is employed to efficiently transfer the extracted power to the output. A dual-input feature enables the simultaneous maximum power extraction from two harvesters, while a dual-output allows a control circuit to perform complex digital functions at nW power levels. The control circuit reconfigures the converter to improve the efficiency and achieve zero-current and zero-voltage switching. The measurement results of the proposed boost converter, implemented in a 0.18 μm CMOS process, show a peak efficiency of 89.5% when both sources provide a combined input power of 66 μW. In the single-source mode, the converter achieves a peak efficiency of 85.2% at 23 μW for the thermoelectric source and 90.4% at 29 μW for the glucose biofuel cell. The converter can operate from minimum input voltages of 10 mV for the thermoelectric source and 30 mV for the glucose biofuel cell. 

  • 271.
    Katic, Janko
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rodriguez, Saul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    An Efficient Boost Converter Control for Thermoelectric Energy Harvesting2013Inngår i: Electronics, Circuits, and Systems (ICECS), 2013 IEEE 20th International Conference on, IEEE conference proceedings, 2013, s. 385-388Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This paper presents an ultra-low power controlcircuit for a DC-DC boost converter targeting implantablethermoelectric energy harvesting applications. Efficiency of theinput converter is enhanced by utilizing zero-current switchingtechnique. Adaptive delay between ON states of switches assureszero-voltage switching of synchronous rectifier and reducesswitching losses. The control circuit employing both techniquesconsumes an average power of 620nW. This allows the converterto operate from harvested power below 5μW. For voltageconversion ratios above 20, the proposed circuits and techniquesdemonstrate efficiency improvement compared to the state-of-the-art solutions.

  • 272.
    Katic, Janko
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rodriguez, Saul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Analysis of Dead Time Losses in Energy Harvesting Boost Converters for Implantable Biosensors2014Inngår i: NORCHIP, 2014, IEEE conference proceedings, 2014, s. 1-4Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Efficiency of an ultra-low power energy harvesting dc-dc converter depends on its losses and the power consumption of the control circuit. Unlike other loss mechanisms, losses related to dead times have not been thoroughly studied. Therefore, in most cases these losses are not adequately suppressed. This paper investigates dead time losses and their impact on the overall system efficiency. Simple expressions for fast estimation of dead time losses are derived. Analysis shows that in many applications where high voltage conversions are required, such as implantable biosensors, the efficiency reduction due to these losses can easily exceed 2%. The analysis is validated using an adaptive dead time circuit which minimizes the associated losses and improves the overall system efficiency according to the calculated values.

  • 273.
    Kawasaki, Hiroharu
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ohshima, T.
    Yagyu, Y.
    Suda, Y.
    Khartsev, Sergiy
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Grishin, Alex
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    TiO2/TiN/TiO2 heat mirrors by laser ablation of single TiN target2008Inngår i: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 100, nr 1, s. 012038-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Titanium oxide (TiO2 ) and titanium nitride (TiN) multilayered films grown by pulsed laser deposition (PLD) technique have been tested as a heat mirror, which have a high transmittance in the visible region and a high reflectance in the infrared. Three layer TiO2 /TiN/TiO2 heat mirrors were grown on Corning glass substrates ablating single TiN target. Switching of TiO2 -to-TiN layers composition was achieved by changing gas atmosphere (oxygen-to-nitrogen). Grown TiO2 /TiN/TiO2 heat mirrors are highly transparent in visible (above 60% at 525nm), opaque in infrared (10% at 2600nm) and in the range from 400 nm to 2600 nm they possess almost the same properties as films prepared using two targets: TiO2 and TiN. XPS confirms similarity of chemical composition of multilayered TiO2 /TiN films prepared by single TiN and two TiO2 and TiN targets techniques. Furthermore, multifunctional self cleaning properties of TiO2 /TiN heat mirrors are expected through the precise control of the composition of the top TiO2 layer operating as a photocatalyst.

  • 274.
    Khartsev, Sergey I.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Grishin, Alexander M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    High performance latching-type luminescent magneto-optical photonic crystals2011Inngår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 36, nr 15, s. 2806-2808Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the properties of one-dimensional heteroepitaxial all-garnet magneto-optical photonic crystals (MOPCs) composed of alternating quarter-wavelength layers of diamagnetic Sm(3)Ga(5)O(12) and MO-active Bi(2.97)Er(0.03)Al(0.5)Ga(0.5)O(12) garnets rf-magnetron sputtered on Gd(3)Ga(5)O(12)(111) substrate. Substitution of ferric ions by aluminum and gallium improved transparency and induced perpendicular anisotropy in pure bismuth iron garnet. As a result, photonic crystals owned a record high magneto-optical quality and a latching-type (magnetic remnant) Faraday rotation (FR). At the resonance wavelengths 775(640)nm, a specific FR theta(F) - -14.1(14.8) deg/mu m and MO-quality factor Q = 99.3(46.2) deg represent the highest MOPC performance achieved so far.

  • 275. Kilpelainen, S.
    et al.
    Kuitunen, K.
    Tuomisto, F.
    Slotte, J.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kuznetsov, A. Yu.
    Stabilization of Ge-rich defect complexes originating from E centers in Si(1-x)Ge(x):P2010Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, nr 13, s. 132103-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Thermal evolution of vacancy complexes was studied in P-doped ([P] = 10(18) cm(-3)) proton irradiated Si(1-x)Ge(x) with Ge contents of 10%, 20%, and 30% in the range of 250-350 degrees C using positron annihilation spectroscopy. The radiation damage recovers in the course of anneals but the final state differs from that in as-grown samples indicating the presence of small Ge clusters in the samples, contrary to the initially random Ge distribution. The activation energy for the annealing process was estimated to be 1.4+/-0.3 eV and attributed to the dissociation energy of the vacancy-phosphorus-germanium (V-P-Ge) complex.

  • 276. Kobayashi, Takane
    et al.
    Primetzhofer, Daniel
    Linnarsson, Margareta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ion-stimulated desorption in the medium-energy regime2014Inngår i: Japanese Journal of Applied Physics, ISSN 0021-4922, E-ISSN 1347-4065, Vol. 53, nr 6, s. 060305-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ion-stimulated desorption in the medium-energy regime is investigated using a hydrogen rich Li2O sample. The desorbed yield dependencies for H+ and Li+ on incident ion species H-1(+) and He-4(+) in a medium energy regime are measured. For the mechanism of desorption it is considered that an inner shell electron vacancy is generated in oxygen atoms of the target by the ion impact. This inner shell vacant state is then filled by Auger transition of an electron from surrounding H or Li atoms. The resulting coulomb repulsion between H+ or Li+ and O+ leads to ejection of H+ or Li+ from the surface.

  • 277.
    Kolahdouz Esfahani, Mohammadreza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Application of SiGe(C) in high performance MOSFETs and infrared detectors2011Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Epitaxially grown SiGe(C) materials have a great importance for many device applications. In these applications, (strained or relaxed) SiGe(C) layers are grown either selectively on the active areas, or on the entire wafer. Epitaxy is a sensitive step in the device processing and choosing an appropriate thermal budget is crucial to avoid the dopant out–diffusion and strain relaxation. Strain is important for bandgap engineering in (SiGe/Si) heterostructures, and to increase the mobility of the carriers. An example for the latter application is implementing SiGe as the biaxially strained channel layer or in recessed source/drain (S/D) of pMOSFETs. For this case, SiGe is grown selectively in recessed S/D regions where the Si channel region experiences uniaxial strain.The main focus of this Ph.D. thesis is on developing the first empirical model for selective epitaxial growth of SiGe using SiH2Cl2, GeH4 and HCl precursors in a reduced pressure chemical vapor deposition (RPCVD) reactor. The model describes the growth kinetics and considers the contribution of each gas precursor in the gas–phase and surface reactions. In this way, the growth rate and Ge content of the SiGe layers grown on the patterned substrates can be calculated. The gas flow and temperature distribution were simulated in the CVD reactor and the results were exerted as input parameters for the diffusion of gas molecules through gas boundaries. Fick‟s law and the Langmuir isotherm theory (in non–equilibrium case) have been applied to estimate the real flow of impinging molecules. For a patterned substrate, the interactions between the chips were calculated using an established interaction theory. Overall, a good agreement between this model and the experimental data has been presented. This work provides, for the first time, a guideline for chip manufacturers who are implementing SiGe layers in the devices.The other focus of this thesis is to implement SiGe layers or dots as a thermistor material to detect infrared radiation. The result provides a fundamental understanding of noise sources and thermal response of SiGe/Si multilayer structures. Temperature coefficient of resistance (TCR) and noise voltage have been measured for different detector prototypes in terms of pixel size and multilayer designs. The performance of such structures was studied and optimized as a function of quantum well and Si barrier thickness (or dot size), number of periods in the SiGe/Si stack, Ge content and contact resistance. Both electrical and thermal responses of such detectors were sensitive to the quality of the epitaxial layers which was evaluated by the interfacial roughness and strain amount. The strain in SiGe material was carefully controlled in the meta–stable region by implementingivcarbon in multi quantum wells (MQWs) of SiGe(C)/Si(C). A state of the art thermistor material with TCR of 4.5 %/K for 100×100 μm2 pixel area and low noise constant (K1/f) value of 4.4×10-15 is presented. The outstanding performance of these devices is due to Ni silicide contacts, smooth interfaces, and high quality of multi quantum wells (MQWs) containing high Ge content.The novel idea of generating local strain using Ge multi quantum dots structures has also been studied. Ge dots were deposited at different growth temperatures in order to tune the intermixing of Si into Ge. The structures demonstrated a noise constant of 2×10-9 and TCR of 3.44%/K for pixel area of 70×70 μm2. These structures displayed an improvement in the TCR value compared to quantum well structures; however, strain relaxation and unevenness of the multi layer structures caused low signal–to–noise ratio. In this thesis, the physical importance of different design parameters of IR detectors has been quantified by using a statistical analysis. The factorial method has been applied to evaluate design parameters for IR detection improvements. Among design parameters, increasing the Ge content of SiGe quantum wells has the most significant effect on the measured TCR value.

  • 278.
    Kolahdouz, Esfahani Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A low cost multi quantum SiGe/Si/Schottky structure for high performance IR detectors2011Inngår i: European Solid-State Device Res. Conf., 2011, s. 327-330Konferansepaper (Fagfellevurdert)
    Abstract [en]

    SiGe(C)/Si(C) multi quantum wells (MQWs) individually or in series with a Schottky diode (SQW) have been characterized as the thermistor materials for high performance bolometer application. The thermal response of the thermistor materials is expressed in temperature coefficient of resistance (TCR) and an excellent value of 6%/K is obtained for the SQWs. The noise power spectrum density was also measured and the K 1/f was estimated as low as 4.7×10 -14. The outstanding characteristics for the SQWs are due to low defect density and high interfacial quality in the multilayer structures. These results are very promising for the rising market of low cost IR detectors in the near future.

  • 279.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Adibi, P. Tabib Zadeh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Farniya, Ali Afshar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Shayestehaminzadeh, Seyedmohammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Trybom, Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Di Benedetto, Luigi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Selective Growth of B- and C-Doped SiGe Layers in Unprocessed and Recessed Si Openings for p-type Metal-Oxide-Semiconductor Field-Effect Transistors Application2010Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, nr 6, s. H633-H637Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work presents the pattern dependency of the selective epitaxial growth of boron- and carbon-doped SiGe layers in recessed and unprocessed openings. The layer profile is dependent on deposition time, chip layout, and growth parameters. Carbon and boron doping compensates for the strain in SiGe layers, and when both dopants are introduced, the strain reduction is additive. The incorporation of boron and carbon in the SiGe matrix is a competitive action. The concentration of carbon decreases, whereas the boron amount increases in SiGe layers with higher Ge content. In recessed openings, the Ge content is independent of the recess depth. The strain amount in the grown layers is graded vertically, which is due to the thickness of the epilayer exceeding the critical thickness.

  • 280.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Adibi, P. Tabib Zadeh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Farniya, Ali Afshar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Trybom, Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Di Benedetto, Luigi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Shayestehaminzadeh, Seyedmohammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Selective growth of B- and C-doped SiGe layers in unprocessed and recessed Si openings for pMOSFET application2009Inngår i: EUROCVD 17 / CVD 17, Electrochemical Society, 2009, nr 8 PART 1, s. 81-88Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This work presents pattern dependency of selective epitaxial growth of boron- or carbon-doped SiGe layers in recessed or unprocessed openings. The layer profile and quality of epi-layers were found to be dependent on chip layout and the growth parameters. Carbon- and boron-doping compensated the strain in SiGe layers and when both dopants are introduced the strain reduction was additive. The incorporation of boron and carbon in SiGe matrix showed to be a competitive action. The concentration of carbon decreased when the boron amount increased in SiGe layers with higher Ge content.

  • 281.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Farniya, A. Afshar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Di Benedetto, Luigi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Improvement of infrared detection using Ge quantum dots multilayer structure2010Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 96, nr 21, s. 213516-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Monocrystalline SiGe/Si multiquantum dot and well structures have been manufactured/compared as thermistor materials for infrared detection. The performance of the devices (both the thermal and electrical) has been very sensitive to the quality of the epitaxial layers which is evaluated by the interfacial roughness and strain amount. This study demonstrates that the devices containing quantum dots have higher thermal coefficient resistance 3.4%/K with a noise constant (K-1/f) value of 2x10(-9).

  • 282.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Farniya, Ali Afshar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Improving the performance of SiGe-based IR detectors2010Inngår i: Sige, Ge, And Related Compounds 4: Materials, Processing, And Devices, Electrochemical Society, 2010, nr 6, s. 221-225Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During recent years, single crystalline (Sc) SiGe has been recognized as a new low cost thermistor material for IR detection. In this study the effect of Ge content, pixel size and the Ni silicide on the performance of SiGe/Si thermistor material have been presented. The noise level was decreased for more than one order of magnitude when the Ni silicide layer was integrated below the metal contacts. The silicidation slightly improved TCR values for the detectors(+0.22%/K). However, Increasing the Ge content had the most significant effect on the TCR. A statistical analysis was applied to evaluate the effect of each parameter. It was found using the factorial method that decreasing the pixel size will enhance the TCR value.

  • 283.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Farniya, Ali Afshar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    The performance improvement evaluation for SiGe-based IR detectors2011Inngår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 62, nr 1, s. 72-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    During recent years, single crystalline (Sc) SiGe has been recognized as a new low cost thermistor material for IR detection. In this study the effect of Ge content, pixel size and the Ni silicide on the performance of SiGe/Si thermistor material have been presented. The noise level was decreased for more than one order of magnitude when the Ni silicide layer was integrated below the metal contacts. The silicidation slightly improved TCR values for the detectors (+0.22%/K). However, increasing the Ge content had the most significant effect on the TCR. A statistical analysis was applied to evaluate the effect of each parameter. Using the factorial method, it was realized that decreasing the pixel size would enhance the TCR value.

  • 284.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hållstedt, Julius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Khatibi, Ali
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Wise, Rick
    Riley, Deborah J.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Comprehensive Evaluation and Study of Pattern Dependency Behavior in Selective Epitaxial Growth of B-Doped SiGe Layers2009Inngår i: IEEE transactions on nanotechnology, ISSN 1536-125X, E-ISSN 1941-0085, Vol. 8, nr 3, s. 291-297Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of chip layout and architecture on the pattern dependency of selective epitaxy of B-doped SiGe layers has been studied. The variations of Ge-, B-content, and growth rate have been investigated locally within a wafer and globally from wafer to wafer. The results are described by the gas depletion theory. Methods to control the variation of layer profile are suggested.

  • 285.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hållstedt, Julius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Wise, R.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Selective Epitaxial Growth with Full Control of Pattern Dependency Behavior for pMOSFET Structures2008Inngår i: SIGE, GE, AND RELATED COMPOUNDS 3: MATERIALS, PROCESSING, AND DEVICES / [ed] Harame D; Caymax M; Koester S; Miyazaki S; Rim K; Tillack B; Boquet J; Cressier J; Masini G; Reznicek A; Takagi S, 2008, Vol. 16, nr 10, s. 153-158Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study presents a way to design chips to obtain uniform selective epitaxial growth of SiGe layers in pMOSPET structures. The pattern dependency behavior of tile growth has been controlled over different sizes of transistors. It is shown that the exposed Si coverage of the chip is the main parameter in order to maintain control of the layer profile. This has been explained by gas depletion theory of the growth species in tile stationary boundary layer over tile wafer. The control of SiGe layer profile has been obtained over a wide range of device sizes by optimized process parameters in combination with a water pattern design consisting of dummy features causing uniform gas depletion over the chips of the wafer.

  • 286.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hållstedt, Julius
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Wise, R.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Selective Epitaxial Growth with Full Control of Pattern Dependency Behavior for pMOSFET Structures2009Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 156, nr 3, s. H169-H171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presents a way to design chips to obtain uniform selective epitaxial growth of SiGe layers in p-type metal-oxide-semiconductor field-effect transistor (pMOSFET) structures. The pattern dependency behavior of the growth has been controlled over different sizes of transistors. It is shown that the exposed Si coverage of the chip is the main parameter in order to maintain control of the layer profile. This has been explained by the gas depletion theory of the growth species in the stationary boundary layer over the water. Control of the SiGe layer profile has been obtained over a wide range of device sizes by optimized process parameters in combination with a wafer pattern design consisting of dummy features causing uniform gas depletion over the chips of the wafer.

  • 287.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Maresca, Luca
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ghandi, Reza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Khatibi, Ali
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kinetic Model of SiGe Selective Epitaxial Growth Using RPCVD Technique2010Inngår i: Sige, Ge, And Related Compounds 4: Materials, Processing, And Devices / [ed] D. Harame, J. Boquet, M. Östling, Y. Yeo, G. Masini, M. Caymax, T. Krishnamohan, B. Tillack, S. Bedell, S. Miyazaki, A. Reznicek, S. Koester, Electrochemical Society, 2010, Vol. 33, s. 581-593Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Recently, selective epitaxial growth (SEG) of B-doped SiGe layers has been used in recessed source/drain (S/D) of pMOSFETs. The uniaxial induced strain enhances the carrier mobility in the channel. In this work, a detailed model for SEG of SiGe has been developed to predict the growth rate and Ge content of layers in dichlorosilane(DCS)-based epitaxy using a reduced-pressure CVD reactor. The model considers each gas precursor contributions from the gas-phase and the surface. The gas flow and temperature distribution were simulated in the CVD reactor and the results were exerted as input parameters for Maxwell energy distribution. The diffusion of molecules from the gas boundaries was calculated by Fick's law and Langmuir isotherm theory (in non-equilibrium case) was applied to analyze the surface. The pattern dependency of the selective growth was also modeled through an interaction theory between different subdivisions of the chips. Overall, a good agreement between the kinetic model and the experimental data were obtained.

  • 288.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Maresca, Luca
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ghandi, Reza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Khatibi, Ali
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kinetic Model of SiGe Selective Epitaxial Growth Using RPCVD Technique2011Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 158, nr 4, s. H457-H464Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, selective epitaxial growth (SEG) of B-doped SiGe layers has been used in recessed source/drain (S/D) of pMOSFETs. The uniaxial induced strain enhances the carrier mobility in the channel. In this work, a detailed model for SEG of SiGe has been developed to predict the growth rate and Ge content of layers in dichlorosilane(DCS)-based epitaxy using a reduced-pressure CVD reactor. The model considers each gas precursor contributions from the gas-phase and the surface. The gas flow and temperature distribution were simulated in the CVD reactor and the results were exerted as input parameters for Maxwell energy distribution. The diffusion of molecules from the gas boundaries was calculated by Fick's law and Langmuir isotherm theory (in non-equilibrium case) was applied to analyze the surface. The pattern dependency of the selective growth was also modeled through an interaction theory between different subdivisions of the chips. Overall, a good agreement between the kinetic model and the experimental data were obtained.

  • 289.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Maresca, Luca
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Riley, D.
    Wise, R.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    New method to calibrate the pattern dependency of selective epitaxy of SiGe layers2009Inngår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 53, nr 8, s. 858-861Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Selective epitaxial growth (SEG) of Si1-xGex layers on patterned substrates containing isolated, grouped and global chips has been investigated. The interaction between chips on a wafer was studied, and the results are explained by kinetic gas theory for CVD techniques. A test pattern was designed with a series of grouped chips to calibrate the pattern dependency of SEG (both growth rate and Ge content). The amount of exposed Si coverage on chips in the test pattern ranged between 0.05 and 37%. The layer profile of the calibration pattern was compared to profiles on wafers having a global chip design. A model was developed to estimate the Ge content on substrates with a global design.

  • 290.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ghandi, Reza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    B-doped SIGE(C) materials for high performance devices2011Inngår i: Boron: Compounds, Production and Application / [ed] Gary L. Perkins, Nova Science Publishers, Inc., 2011, s. 295-326Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    B-doping of group IV materials using B2H6 is widely performed in chemical vapor deposition (CVD) technique. The B-doped SiGe layers are grown epitaxially as the base layer in HBTs for increased frequency performance in mixed signal radio frequency (RF) applications. These layers may also apply as a stressor material in source/drain of pMOSFETs for higher carrier mobility in a uniaxially strained channel. Furthermore, contact layers performance in terms of thermal stability and resistivity are improved by adopting highly boron doped (B-doped) layers in various electronic components. However, high diffusion of boron can limit the thermal budget for fabrication of the devices. One way to suppress this problem is integration of carbon in B-doped layers where the carbon diffuses out but boron stays in the SiGe layers. Therefore, growing highly B-doped group IV materials with high thermal stability and layer quality is a challenging issue. This chapter deals with growth kinetics, dopant incorporation, thermal stability, strain compensation, strain relaxation and defect formation of B-doped SiGe layers grown by reduced pressure CVD. The ion implantation and some of its processing issues regarding B-doping will be discussed.

  • 291.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Salemi, Arash
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Moeen, Mahdi
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kinetic Modeling of Low Temperature Epitaxy Growth of SiGe Using Disilane and Digermane2012Inngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 159, nr 5, s. H478-H481Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low temperature epitaxy (LTE) in Chemical Vapor Deposition (CVD) refers to 350-650 degrees C interval. This temperature range is critical for this process since the thermal and lattice mismatch (or strain relaxation) issues diminish in advanced BiCMOS processing. The modeling of the epitaxy process is a vital task to increase the understanding the growth process and to design any desired device structure. In this study, an empirical model for Si2H6/Ge2H6-based LTE of SiGe is developed and compared with experimental work. The model can predict the number of free sites on Si surface, growth rate of Si and SiGe, and the Ge content at low temperatures. A good agreement between the model and the experimental data is obtained.

  • 292.
    Kolahdouz, Mohammadreza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    High performance infra-red detectors based on Si/SiGe multilayers quantum structure2012Inngår i: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 177, nr 17, s. 1563-1566Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, single crystalline (Sc) Si/SiGe multi quantum structure has been recognized as a new low-cost thermistor material for IR detection. Higher signal-to-noise (SNR) ratio and temperature coefficient of resistance (TCR) than existing thermistor materials have converted it to a candidate for infrared (IR) detection in night vision applications. In this study, the effects of Ge content, C doping and the Ni silicidation of the contacts on the performance of SiGe/Si thermistor material have been investigated. Finally, an uncooled thermistor material with TCR of -4.5%/K for 100 μm × 100 μm pixel sizes and low noise constant (K 1/f) value of 4.4 × 10 -15 is presented. The outstanding performance of the devices is due to Ni silicide contacts, smooth interfaces, and high quality multi quantum wells (MQWs) containing high Ge content.

  • 293. Kolahdouz, Z.
    et al.
    Kolahdouz, M.
    Ghanbari, H.
    Mohajerzadeh, S.
    Naureen, Shagufta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Substrate engineering for Ni-assisted growth of carbon nano-tubes2012Inngår i: Materials Science & Engineering: B. Solid-state Materials for Advanced Technology, ISSN 0921-5107, E-ISSN 1873-4944, Vol. 177, nr 17, s. 1542-1546Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The growth of carbon multi-walled nano-tubes (MWCNTs) using metal catalyst (e.g. Ni, Co, and Fe) has been extensively investigated during the last decade. In general, the physical properties of CNTs depend on the type, quality and diameter of the tubes. One of the parameters which affects the diameter of a MWCNT is the size of the catalyst metal islands. Considering Ni as the metal catalyst, the formed silicide layer agglomerates (island formation) after a thermal treatment. One way to decrease the size of Ni islands is to apply SiGe as the base for the growth. In this study, different methods based on substrate engineering are proposed to change/control the MWCNT diameters. These include (i) well-controlled oxide openings containing Ni to miniaturize the metal island size, and (ii) growth on strained or partially relaxed SiGe layers for smaller Ni silicide islands.

  • 294. Koliopoulou, S
    et al.
    Dimitrakis, P
    Goustouridis, D
    Normand, P
    Pearson, Christopher
    KTH.
    Petty, M C
    Radamson, Henry H
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Tsoukalas, D
    Metal nano-floating gate memory devices fabricated at low temperature2006Inngår i: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 83, nr 4-9, s. 1563-1566Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this communication, we report on the realization of low-temperature processed Electrically Erasable Programmable Read-Only Memory (EEPROM) like device with embedded gold nanoparticles. The realization is based on the fabrication of a V-groove SiGe Metal Oxide Semiconductor Field Effect Transistor (MOSFET), the functionalization of a gate oxide followed by self-assembly of gold nanoparticles and finally, the deposition of an organic insulator by Langmuir-Blodgett (LB) technique. Such structures were processed at a temperature lower than 400 degrees C. The electrical characteristics of the final hybrid Metal Insulator Semiconductor FET (MISFET) memory cells were evaluated in terms of memory window and program/erase voltage pulses. A model describing the memory characteristics, based on the electronic properties of the gate stack materials, is presented.

  • 295. Kolokoltsev, O.
    et al.
    Gómez-Arista, I.
    Qureshi, N.
    Acevedo, A.
    Ordóñez-Romero, C. L.
    Grishin, Alexander M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Erratum to: Compression gain of spin wave signals in a magnonic YIG waveguide with thermal non-uniformity (J. Magn. Magn. Mater. (2014) 377C (1-5) DOI 10.1016/j.jmmm.2014.10.001)2016Inngår i: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 409, s. 163-165Artikkel i tidsskrift (Fagfellevurdert)
  • 296. Konstantinov, A.
    et al.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zaring, C.
    Keri, I.
    Svedberg, J. -O
    Gumaelius, K.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Reimark, M.
    Operation of Silicon Carbide BJTs Free from Bipolar Degradation2010Inngår i: SILICON CARBIDE AND RELATED MATERIALS 2009, PTS 1 AND 2 / [ed] Bauer, AJ; Friedrichs, P; Krieger, M; Pensl, G; Rupp, R; Seyller, T, 2010, s. 1057-1060Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The mechanisms of bipolar degradation in silicon carbide BJTs are investigated and identified. Bipolar degradation occurs as result of stacking fault (SF) growth within the low-doped collector region. A stacking fault blocks vertical current transport through the collector, driving the defective region into saturation. This results in considerable drop of emitter current gain if the BJT is run at a reasonably low collector-emitter bias. The base region does not play any significant role in bipolar degradation. Long-term stress tests have shown full stability of large-area high-power BJTs under minority carrier injection conditions provided the devices are fabricated using low Basal Plane Dislocation (BPD) material. However, an approximately 20% current gain compression is observed for the first 30-60 hours of burn-in under common emitter operation, which is related to instability of surface recombination in the passive base region.

  • 297. Koo, S. -M
    et al.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Forsberg, U.
    Janzen, E.
    Simulation and Measurement of Switching Characteristics of 4H-SiC Buried-Gate JFETs2003Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 433-436, s. 773-776Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Buried-gate junction field-effect transistors (JFETs) have been fabricated in 4H polytype silicon carbide (SiC). The dynamic switching characteristics of the JFETs in a circuit with inductive load have been characterized. The drain voltage rise/fall time of ∌30 ns and 25 ns have been observed for turn-off and turn-on, respectively. The results have been compared to numerical mixed-mode circuit simulations with finite element structures.

  • 298. Koo, S. -M
    et al.
    Khartsev, S. I.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Grishin, Alexander. M.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Towards ferroelectric field effect transistors in 4H-silicon carbide2002Inngår i: Materials Research Society Symposium - Proceedings, Boston, MA, 2002, Vol. 742, s. 371-379Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We report on the integration of ferroelectric Pb(Zr,Ti)O3 (PZT) thin films on 4H-silicon carbide and their electrical properties. The structures of metal-ferroelectric-(insulator)-semiconductor MF(I)S and metal-ferroelectric-metal-insulator-semiconductor MFMIS have been fabricated and characterized. The MFMIS structures of Au/PZT/Pt/Ti/SiO2/SiC have shown fully saturated P-E hysteresis loops with remnant polarization Pr = 14.2 ΌC/cm2 and coercive field Ec = 58.9 kV/cm. The MFIS structures exhibited stable capacitance-voltage C-V loops with low conductance (&lt;0.1 mS/cm2, tan Ύ ∌ 0.0007 at 12 V, 400 kHz) and memory window as wide as 10 V, when a 5 nm-thick Al2O3 was used as a high bandgap (Eg ∌ 9 eV) barrier buffer layer between PZT (Eg ∌ 3.5 eV) and SiC (Eg ∌ 3.2 eV). Both structures on n- and p- SiC have shown electrical properties promising for the application to the gate stacks for the SiC field-effect transistors (FETs) and the design and process issues on different types of the metal-ferroelectric-silicon carbide field-effect transistors (FETs) have also been proposed.

  • 299. Koo, S. -M
    et al.
    Lee, S. -K
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Forsberg, U.
    Janzen, E.
    Influence of trenching effect on the characteristics of buried-gate SiC junction field-effect transistors2002Inngår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 389-393, nr 2, s. 1235-1238Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two different structures of junction field-effect transistors in 4H-SiC, with and without trenching effect in the channel region, have been fabricated and characterized. The devices formed with metal mask show a trenching profile (>∌0.2 Όm) after dry etch in the channel groove region and exhibited static induction transistor (SIT)-like characteristics in the sub-threshold region of I-V curves as the channel thickness decreases. The devices without trenching effect have been processed by using a wet-etched oxide mask resulting in a sloped dry-etch profile (Ξ=∌30°) in the channel, and consequently showed well-saturated drain characteristics for all the channel thicknesses. The conduction mechanisms in these JFETs are examined by the potential profiles from two dimensional numerical simulations.

  • 300. Koo, S.-M.
    et al.
    Khartsev, S. I.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Grishin, Alexander. M.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Characteristics of PZT/Al2O3 stack on SiC demonstrated in a NVFET2003Inngår i: 34th IEEE Semicondctor Interface Specialists Conference, 2003, 2003Konferansepaper (Fagfellevurdert)
3456789 251 - 300 of 724
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