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  • 101.
    Dentoni Litta, Eugenio
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Mobility enhancement by integration of TmSiO IL in 0.65nm EOT high-k/metal gate MOSFETs2013Ingår i: 2013 Proceedings of the European Solid-State Device Research Conference (ESSDERC), IEEE Computer Society, 2013, s. 155-158Konferensbidrag (Refereegranskat)
    Abstract [en]

    Thulium silicate has been demonstrated as a possible replacement of chemical oxide interfacial layers for extended scalability of high-k/metal gate MOSFETs. In this work, thulium silicate was integrated in a scaled HfO 2/TiN gate-last CMOS process, achieving an EOT of 0.65 nm and well-behaved and reproducible IV and CV characteristics with almost symmetric threshold voltages, low subthreshold slope and low hysteresis. Comparison with reference devices employing chemical oxide interfacial layers shows improvement in terms of leakage current density and electron and hole mobility. Specifically, channel mobility is enhanced by 20% in N-MOSFETs and by 15% in P-MOSFETs at an inversion charge density of 1013cm-2, yielding values of 180 and 75 cm2/Vs at EOT = 0.65 and 0.8 nm respectively.

  • 102.
    Dentoni Litta, Eugenio
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Threshold voltage control in TmSiO/HfO2 high-k/metal gate MOSFETs2015Ingår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 108, s. 24-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-k interfacial layers have been proposed as a way to extend the scalability of Hf-based high-k/metal gate CMOS technology, which is currently limited by strong degradations in threshold voltage control, channel mobility and device reliability when the chemical oxide (SiOx) interfacial layer is scaled below 0.4 nm. We have previously demonstrated that thulium silicate (TmSiO) is a promising candidate as a high-k interfacial layer, providing competitive advantages in terms of EOT scalability and channel mobility. In this work, the effect of the TmSiO interfacial layer on threshold voltage control is evaluated, showing that the TmSiO/HfO2 dielectric stack is compatible with threshold voltage control techniques commonly used with SiOx/HfO2 stacks. Specifically, we show that the flatband voltage can be set in the range -1 V to +0.5 V by the choice of gate metal and that the effective workfunction of the stack is properly controlled by the metal workfunction in a gate-last process flow. Compatibility with a gate-first approach is also demonstrated, showing that integration of La2O3 and Al2O3 capping layers can induce a flatband voltage shift of at least 150 mV. Finally, the effect of the annealing conditions on flatband voltage is investigated, finding that the duration of the final forming gas anneal can be used as a further process knob to tune the threshold voltage. The evaluation performed on MOS capacitors is confirmed by the fabrication of TmSiO/HfO2/TiN MOSFETs achieving near-symmetric threshold voltages at sub-nm EOT.

  • 103.
    Dev, Apurba
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Dev Choudhury, Bikash
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Abedin, Ahmad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Fabrication of Periodic Nanostructure Assemblies by Interfacial Energy Driven Colloidal Lithography2014Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 24, nr 29, s. 4577-4583Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel interfacial energy driven colloidal lithography technique to fabricate periodic patterns from solution-phase is presented and the feasibility and versatility of the technique is demonstrated by fabricating periodically arranged ZnO nanowire ensembles on Si substrates. The pattern fabrication method exploits different interfaces formed by sol-gel derived ZnO seed solution on a hydrophobic Si surface covered by a monolayer of colloidal silica spheres. While the hydrophobic Si surface prevents wetting by the seed solution, the wedge shaped regions surrounding the contact point between the colloidal particles and the Si substrate trap the solution due to interfacial forces. This technique allows fabrication of uniform 2D micropatterns of ZnO seed particles on the Si substrate. A hydrothermal technique is then used to grow well-defined periodic assemblies of ZnO nanowires. Tunability is demonstrated in the dimensions of the patterns by using silica spheres with different diameters. The experimental data show that the periodic ZnO nanowire assembly suppresses the total reflectivity of bare Si by more than a factor of 2 in the wavelength range 400-1300 nm. Finite-difference time-domain simulations of the wavelength-dependent reflectivity show good qualitative agreement with the experiments. The demonstrated method is also applicable for other materials synthesized by solution chemistry.

  • 104.
    Dev Choudhury, Bikash
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Abedin, Ahmad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Dev, Apurba
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Sanatinia, Reza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Anand, Srinivasan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Halvledarmaterial, HMA.
    Silicon micro-structure and ZnO nanowire hierarchical assortments for light management2013Ingår i: Optical Materials Express, ISSN 2159-3930, E-ISSN 2159-3930, Vol. 3, nr 8, s. 1039-1048Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present fabrication and optical characterization of Si microstructure-ZnO nanowire (NWs) hierarchical structures for light management. Random and periodic hierarchical structures constituting Si micro pillar or micro pyramid arrays with overgrown ZnO NWs have been fabricated. Inexpensive colloidal lithography in combination with dry and wet chemical etching is used to fabricate Si microstructures, and ZnO NWs are grown by hydrothermal synthesis. The periodic Si micro pyramid-ZnO NWs hierarchical structure shows broadband antireflection with average reflectance as low as 2.5% in the 300-1000 nm wavelength range. A tenfold enhancement in Raman intensity is observed in this structure compared to planar Si sample. These hierarchical structures with enriched optical properties and high surface to volume ratio are promising for photovoltaic (PV) and sensor applications.

  • 105.
    Di Benedetto, Luigi
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kolahdouz, Mohammadreza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, B. Gunnar
    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), Mikroelektronik och Informationsteknik, IMIT.
    Strain balance approach for optimized signal-to-noise ratio in SiGe quantum well bolometers2009Ingår i: ESSDERC 2009 - Proceedings of the 39th European Solid-State Device Research Conference, 2009, s. 101-104Konferensbidrag (Refereegranskat)
    Abstract [en]

    This work presents thermal and electrical characterization of SiGe/Si multi-quantum wells (MQWs) with different layer profiles in complete bolometer structures. The thermal property of the bolometers was studied by measuring thermal coefficient of resistivity (TCR) through I-V curves for five temperatures (25, 40, 55, 80 and 100°C) and for four different pixel areas. The results show a strong dependency of TCR on the Si/SiGe layer thickness and the presence of dopant impurity in the MQW. The noise measurements of MQWs were performed carefully by eliminating all external contributions and the noise spectroscopy provided the noise characteristic parameters. The results demonstrate that the noise depends on the geometric size of the MQW and it increases with decreasing of the pixel area. The investigations show the noise level in the bolometer structures is sensitive to any dopant segregation from the contact layers.

  • 106.
    Domeij, Martin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Danielsson, Erik
    Liu, W.
    Zimmermann, U.
    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.
    Measurements and simulations of self-heating and switching with 4H-SIC power BJTs2003Ingår i: IEEE International Symposium on Power Semiconductor Devices and ICs (ISPSD), Cambridge, 2003, s. 375-378Konferensbidrag (Refereegranskat)
    Abstract [en]

    Transient measurements and device simulations were performed to investigate self-heating and switching with 4H-SiC BJTs. A current gain decrease was found during self-heating presumably due to reduced electron mobility with increasing temperature. Surface recombination increased the simulated maximum temperature but the current gain decrease during self-heating was similar as for bulk recombination. A fast switching of 0.5 A and 200 V was shown with a voltage rise-time of about 70 ns and fall-time of 50 ns. Turn-off measurements show a noticeable delay time before fall-off of the emitter current, indicating a significant amount of stored carriers in the base.

  • 107.
    Domeij, Martin
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zaring, C.
    Konstantinov, A. O.
    Nawaz, M.
    Svedberg, J-O
    Gumaelius, K.
    Keri, I.
    Lindgren, A.
    Hammarlund, B.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Reimark, M.
    2.2 kV SiC BJTs with low V(CESAT) fast switching and short-circuit capability2010Ingår 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. 1033-1036Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper reports large active area (15 mm(2)) 4H-SiC BJTS with a low V(CESAT)=0.6 V at 1(C)=20 A (J(C)=133 A/cm(2)) and an open-base breakdown voltage BV(CEO)=2.3 kV at T=25 degrees C. The corresponding room temperature specific on-resistance R(SP.ON)=4.5 m Omega cm(2) is to the authors knowledge the lowest reported value for a large area SiC BJT blocking more than 2 kV. The onstate and blocking characteristics were analyzed by device simulation and found to be in good agreement with measurements. Fast switching with VcE rise- and fall-times in the range of 20-30 ns was demonstrated for a 6 A 1200 V rated SiC BJT. It was concluded that high dynamic base currents are essential for fast switching to charge the BJT parasitic base-collector capacitance. In addition, 10 mu s short-circuit capability with V(CE)=800 V was shown for the 1200 V BJT.

  • 108. Donetti, L.
    et al.
    Gamiz, F.
    Thomas, S.
    Whall, T. E.
    Leadley, D. R.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hole effective mass in silicon inversion layers with different substrate orientations and channel directions2011Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 110, nr 6, s. 063711-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We explore the possibility to define an effective mass parameter to describe hole transport in inversion layers in bulk MOSFETs and silicon-on-insulator devices. To do so, we employ an accurate and computationally efficient self-consistent simulator based on the six-band k . p model. The valence band structure is computed for different substrate orientations and silicon layer thicknesses and is then characterized through the calculation of different effective masses taking account of the channel direction. The effective masses for quantization and density of states are extracted from the computed energy levels and subband populations, respectively. For the transport mass, a weighted averaging procedure is introduced and justified by comparing the results with hole mobility from experiments and simulations.

  • 109. Donetti, L.
    et al.
    Gámiz, F.
    Thomas, S. M.
    Whall, T. E.
    Leadley, D. R.
    Hellström, Per -Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    On the effective mass of holes in inversion layers2011Ingår i: International Conference on Ultimate Integration on Silicon, 2011, s. 50-53Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study hole inversion layers in bulk MOSFETs and silicon-on-insulator devices employing a self-consistent simulator based on the six-band kp model. Valence Band structure is computed for different device orientations and silicon layer thicknesses, and then it is characterized through the calculation of different effective masses.

  • 110. Driussi, F.
    et al.
    Esseni, D.
    Selmi, L.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, B. Gunnar
    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.
    Grasby, T. J.
    Leadley, D. R.
    Mescot, X.
    On the electron mobility enhancement in biaxially strained Si MOSFETs2008Ingår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 52, nr 4, s. 498-505Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports a detailed experimental and simulation study of the electron mobility enhancement induced by the biaxial strain in (001) silicon MOSFETs. To this purpose, ad hoc test structures have been fabricated on strained Si films grown on different SiGe virtual substrates and the effective mobility of the electrons has been extracted. To interpret the experimental results, we performed simulations using numerical solutions of Schroedinger-Poisson equations to calculate the charge and the momentum relaxation time approximation to calculate the mobility. The mobility enhancement with respect to the unstrained Si device has been analyzed as a function of the Ge content of SiGe substrates and of the operation temperature.

  • 111. Duan, Ningyuan
    et al.
    Luo, Jun
    Wang, Guilei
    Liu, Jinbiao
    Simoen, Eddy
    Mao, Shujuan
    Radamson, Henry
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Wang, Xiaolei
    Li, Junfeng
    Wang, Wenwu
    Zhao, Chao
    Ye, Tianchun
    Reduction of NiGe/n- and p-Ge Specific Contact Resistivity by Enhanced Dopant Segregation in the Presence of Carbon During Nickel Germanidation2016Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 63, nr 11, s. 4546-4549Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This brief explores the specific contact resistivity (rho(c)) of NiGe/n- and p-Ge contacts with and without carbon pregermanidation implantation. It is found that in the presence of carbon, not only the thermal stability of NiGe films is improved, but also the rho(c) of the NiGe/n- and p-Ge contacts is reduced remarkably due to enhanced phosphorus (P) and boron (B) dopant segregation (DS) at the NiGe/Ge interface after nickel germanidation. At 500 degrees C germanidation temperature, the.c values are reduced from 1.1 x 10(-4) Omega-cm(2) and 2.9 x 10(-5) Omega-cm(2) for NiGe/n- and p-Ge contacts without carbon to 7.3 x 10(-5) Omega-cm(2) and 1.4 x 10(-5) Omega-cm(2) for their counterparts with carbon, respectively.

  • 112. Dumas, Randy K.
    et al.
    Iacocca, E.
    Bonetti, S.
    Redjai Sani, Sohrab
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Mohseni, Seyed Majid
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Eklund, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Persson, J.
    Heinonen, O.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Spin-Wave-Mode Coexistence on the Nanoscale: A Consequence of the Oersted-Field-Induced Asymmetric Energy Landscape2013Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 110, nr 25, s. 257202-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It has been argued that if multiple spin wave modes are competing for the same centrally located energy source, as in a nanocontact spin torque oscillator, that only one mode should survive in the steady state. Here, the experimental conditions necessary for mode coexistence are explored. Mode coexistence is facilitated by the local field asymmetries induced by the spatially inhomogeneous Oersted field, which leads to a physical separation of the modes, and is further promoted by spin wave localization at reduced applied field angles. Finally, both simulation and experiment reveal a low frequency signal consistent with the intermodulation of two coexistent modes.

  • 113. Edmondson, P. D.
    et al.
    Parish, C. M.
    Zhang, Y.
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Miller, M. K.
    Helium bubble distributions in a nanostructured ferritic alloy2013Ingår i: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 434, nr 1-3, s. 210-216Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A 14YWT nanostructured ferritic alloy (NFA) was implanted with He + ions to fluences of 6.75 × 1021 He m-2 at 400 °C in order to simulate the effects of high He concentrations produced in advanced fission and future fusion reactors at an accelerated timescale. The He bubble size distributions associated with specific microstructural features were characterized by a combination of transmission electron microscopy and atom probe tomography. Helium bubbles were observed on grain boundaries, dislocations, and on the surfaces of nanoclusters and larger Ti(N,C) precipitates. A polydisperse distribution of bubble sizes was observed in the ferrite matrix. With the exception of He bubbles on dislocations, bubbles were observed to increase in size with increasing fluence. The combined TEM and APT data indicates that ∼4.4% of the bubbles are located on coarse precipitates, ∼12.2% at dislocations, ∼14.4% at grain boundaries, and ∼48.6% on nanoclusters, and the remainder as isolated bubbles in the ferrite matrix. The abundances of these different trapping sites, especially the nanoclusters, might reduce the availability and mobility of He, and possibly the susceptibility of these alloys to He embrittlement.

  • 114. Edmondson, P. D.
    et al.
    Parish, C. M.
    Zhang, Y.
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Miller, M. K.
    Helium entrapment in a nanostructured ferritic alloy2011Ingår i: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 65, nr 8, s. 731-734Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A nanostructured ferritic alloy was irradiated with He+ to simulate service in a nuclear reactor and to test the hypothesis that the surface of nanoclusters is a preferential nucleation site for He bubbles. Transmission electron microscopy and atom probe tomography showed direct evidence of He bubble nucleation on the surfaces of nanoclusters and Ti(N,C) precipitates, and along grain boundaries and dislocations, thereby demonstrating an alloy design approach to improve the radiation tolerance of structural steels in the extreme environments found in nuclear reactors.

  • 115.
    Eklund, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Microwave Frequency Stability and Spin Wave Mode Structure in Nano-Contact Spin Torque Oscillators2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Dagens snabba utveckling inom informationsteknik drivs på av ständigt växande informationsmängder och deras samhällsanvändning inom allt från resursoptimering till underhållning. Utvecklingen möjliggörs till stor del hårdvarumässigt av miniatyrisering och integrering av elektroniska komponenter samt trådlös kommunikation med allt större bandbredd och högre överföringshastighet. Det senare uppnås främst genom utnyttjande av högre radiofrekvenser i teknologiskt tidigare oåtkomliga delar av spektrumet. Frekvensutnyttjandet har det senaste årtiondet ökat markant i mikrovågsområdet med typiska frekvenser runt 2.4 GHz och 5.2-5.8 GHz.

    I den spinntroniska oscillatorn (STO:n) möjliggörs frekvensgenerering i det breda området från 0.1 GHz upp till över 65 GHz av en komponent med mikrometerstorlek som kan integreras direkt i CMOS-mikrochip. Till skillnad från i konventionella radiokretsar med oscillatorer konstruerade av integrerade transistorer och spolar, genereras mikrovågsfrekvensen direkt i STO:ns magnetiska material och omvandlas därefter till en elektrisk signal genom komponentens magnetoresistans. Dessa materialegenskaper möjliggör ett tillgängligt frekvensband med extrem bredd i en och samma STO, som därtill kan frekvensmoduleras direkt genom sin styrström och på så sätt förenklar konstruktionen av sändarsystem. STO:ns icke-linjära egenskaper kan potentiellt också användas för att i en och samma komponent blanda ned mottagna mikrovågssignaler och på så sätt förenkla konstruktionen även av mikrovågsmottagare.

    STO:ns signalegenskaper bestäms av det magnetiska materialets fysik i form av magnetiseringsdynamik driven av elektriskt genererade spinnströmmar. I denna avhandling studeras denna dynamik experimentellt med särskilt fokus på frekvensstabiliteten i den hittills mest stabila STO-typen; nanokontakts-STO:n. Genom mätningar i tidsdomän av STO:ns elektriska signaler runt 25 GHz har frekvensstabiliteten funnits hänga samman med den typ av icke-linjärt beteende som också funnits vara utmärkande för tillverkningsvariationen i komponenterna. Mikroskopiska undersökningar av materialet visar att en trolig källa till denna variation är den magnetiska metallens uppbyggnad i form av korn i storleksordningen 30 nm, och datorsimuleringar av en sådan materialstruktur har visats kunna reproducera de experimentella resultaten. Därtill har en metod utvecklats för att med röntgenstrålning direkt mäta de små, magnetiska mikrovågsrörelserna i materialet. Denna röntgenteknik möjliggör detaljerade experimentella studier av magnetiseringsdynamiken och kan användas för att verifiera och vidareutveckla den existerande teorin för mikrovågsspinntronik.

    Sammantaget förs STO-teknologin genom denna studie ett steg närmare sina tänkbara samhällsbreda tillämpningar inom snabb, trådlös kommunikation för massproducerade produkter med integrerad sensor- och datorfunktionalitet.

  • 116.
    Eklund, Anders
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Bonetti, Stefano
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Sani, Sohrab R.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Mohseni, Seyed Majid
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Persson, Johan
    Chung, Sunjae
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Banuazizi, S. Amir Hossein
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik.
    Iacocca, Ezio
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Dependence of the colored frequency noise in spin torque oscillators on current and magnetic field2014Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, nr 9, s. 092405-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The nano-scale spin torque oscillator (STO) is a compelling device for on-chip, highly tunable microwave frequency signal generation. Currently, one of the most important challenges for the STO is to increase its longer-time frequency stability by decreasing the 1/f frequency noise, but its high level makes even its measurement impossible using the phase noise mode of spectrum analyzers. Here, we present a custom made time-domain measurement system with 150MHz measurement bandwidth making possible the investigation of the variation of the 1/f as well as the white frequency noise in a STO over a large set of operating points covering 18-25GHz. The 1/f level is found to be highly dependent on the oscillation amplitude-frequency non-linearity and the vicinity of unexcited oscillation modes. These findings elucidate the need for a quantitative theoretical treatment of the low-frequency, colored frequency noise in STOs. Based on the results, we suggest that the 1/f frequency noise possibly can be decreased by improving the microstructural quality of the metallic thin films.

  • 117.
    Eklund, Anders
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Bonetti, Stefano
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Sani, Sohrab R.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Persson, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Mohseni, Seyed Majid
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Malm, Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    1/f and white frequency noise in a synchronized spin torque oscillator pair2011Ingår i: 56th Annual Conference on Magnetism and Magnetic Materials, 2011, s. 504-504Konferensbidrag (Refereegranskat)
  • 118.
    Eklund, Anders
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Dvornik, Mykola
    Göteborgs universitet.
    Qejvanaj, Fatjon
    NanOsc AB.
    Jiang, Sheng
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Chung, Sunjae
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. Göteborgs universitet.
    Dumas, Randy K.
    Göteborgs universitet.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. Göteborgs universitet.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Nonlinearity, frequency stability and device-to-device variability in nano-contact spin torque oscillators with grainy thin filmsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    In nano-contact spin torque oscillators with a frequency range of 10-65 GHz, the propagating spin wave mode attracts interest due both to its high frequency stability and prospective use in magnonic devices. Its dependence of the frequency on the bias current however displays device-to-device variability on the order of several hundred MHz, with device specific nonlinearities that can be either continuous or discontinuous and have negative impact on the frequency stability. A model for this behavior is however still lacking. By using micromagnetic simulations, we investigate the impact of imperfections in the spin wave-carrying free magnetic layer and find that nonlinearities can be created when the propagating spin wave is reflected back to the active region. The oscillation then self-locks at the frequency of the resonant wavelength, resulting in a standing spin wave pattern. Simulations including nine randomly generated film structures with 30 nm-sized grains and exchange-reduced inter-grain boundaries give qualitative and partially quantitative agreement with experimental measurements. The results point out the spin wave-reflecting grain boundaries as a source of device nonlinearity, manufacturing variability and frequency destabilization.

  • 119.
    Eklund, Anders J.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Redjai Sani, Sohrab
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Mohseni, Seyed Majid
    NanOsc AB.
    Persson, Johan
    NanOsc AB.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Åkerman, Johan
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Triple mode-jumping in a spin torque oscillator2013Ingår i: 2013 22nd International Conference on Noise and Fluctuations, ICNF 2013, New York: IEEE conference proceedings, 2013, s. 6578965-Konferensbidrag (Refereegranskat)
    Abstract [en]

    In a nano-contact Co/Cu/NiFe spin torque oscillator, mode-jumping between up to three frequencies within 22.5-24.0 GHz is electrically observed in the time domain. The measurements reveal toggling between two states with differing oscillation amplitude, of which the low-amplitude state is further divided into two rapidly alternating modes. Analysis of the mode dwell time statistics and the total time spent in each mode is carried out, and it is found that in both aspects the balance between the modes is greatly altered with the DC drive current.

  • 120.
    Elahipanah, Hossein
    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.
    Buono, Benedetto
    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.
    Process variation tolerant 4H-SiC power devices utilizing trench structures2013Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 740-742, s. 809-812Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicon carbide (SiC) is one of the most attractive semiconductors for high voltage applications. The breakdown voltage of SiC-based devices highly depends on the variation of the fabrication process including doping of the epilayers and the etching steps. In this paper, we show a way to diminish this variability by employing novel trench structures. The influence of the process variations in terms of doping concentration and etching has been studied and compared with conventional devices. The breakdown voltage variation (ΔVBr) of 450 V and 2100 V is obtained for the ±20% variation of doping concentration of the devices with and without the trench structures, respectively. For ±20% variation in etching steps, the maximum ΔVBR of 380 V is obtained for the device with trench structures in comparison to 1800 V for the conventional structure without trench structures. These results show that the breakdown voltage variation is significantly reduced by utilizing the proposed structure.

  • 121.
    Elahipanah, Hossein
    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.
    Zetterling, Calr-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.
    Intertwined Design: A Novel Lithographic Method to Realize Area Efficient High Voltage SiC BJTs and Darlington Transistors2016Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 63, nr 11, s. 4366-4372Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A novel lithographic method called intertwined design is demonstrated for high-power SiC devices to improve the area usage and current drive with more uniform current distribution along the device. The higher current drive is achieved by employing the inactive area underneath the base metal contact pads; more uniform current distribution is obtained by the center-base design; whereas the hexagon and square cell geometries result in >15% higher current density at lower on-resistance compared with the conventional finger design. For the first time, we have experimentally presented the intertwined design to marry these advantages and realize a high-efficient SiC power device. Center-base high-voltage 4H–SiC BJTs and Darlington pairs with different square and hexagon cell geometries are fabricated and compared with conventional designs to prove the ability of the intertwined design. The method can widely be used for large-area high-voltage BJTs as well as for integrated devices.

  • 122.
    Elahipanah, Hossein
    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.
    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.
    4.5-kV 20-mΩ. cm2 Implantation-Free 4H-SiC BJT with Trench Structures on the Junction Termination Extension2015Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 821, s. 838-841Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A single-mask junction termination extension withtrench structures is formed to realize a 4.5 kV implantation-free 4H-SiCbipolar junction transistor (BJT). The trench structures are formed on the baselayer with dry etching using a single mask. The electric field distributionalong the structure is controlled by the number and dimensions of the trenches.The electric field is distributed by the trench structures and thus the electricfield crowding at the base and mesa edges is diminished. The design isoptimized in terms of the depth, width, spacing, and number of the trenches toachieve a breakdown voltage (VB) of 4.5 kV, which is 85% of thetheoretical value. Higher efficiency is obtainable with finer lithographicresolution leading to smaller pitch, and higher number and narrower trenches.The specific on-resistance (RON) of 20 mΩ.cm2 is measuredfor the small-area BJT with active area of 0.04 mm2. The BV-RONof the fabricated device is very close to the SiC limit and by far exceeds thebest SiC MOSFETs.

  • 123.
    Elahipanah, Hossein
    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.
    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.
    5.8-kV Implantation-Free 4H-SiC BJT With Multiple-Shallow-Trench Junction Termination Extension2015Ingår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 36, nr 2, s. 168-170Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Implantation-free 4H-SiC bipolar junction transistors with multiple-shallow-trench junction termination extension have been fabricated. The maximum current gain of 40 at a current density of 370 A/cm(2) is obtained for the device with an active area of 0.065 mm(2). A maximum open-base breakdown voltage (BV) of 5.85 kV is measured, which is 93% of the theoretical BV. A specific ON-resistance (R-ON) of 28 m Omega.cm(2) was obtained.

  • 124.
    Elahipanah, Hossein
    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.
    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.
    Modification of etched junction termination extension for the high voltage 4H-SiC power devices2016Ingår i: Silicon Carbide and Related Materials, Trans Tech Publications, 2016, s. 978-981Konferensbidrag (Refereegranskat)
    Abstract [en]

    High voltage 4H-SiC bipolar junction transistors (BJTs) with modified etched junction termination extension (JTE) were fabricated and optimized in terms of the length (LJTE) and remaining dose (DJTE) of JTEs. It is found that for a given total termination length (Σ LJTEi), a decremental JTE length from the innermost edge to the outermost mesa edge of the device will result in better modification of the electric field. A breakdown voltage (BV) of 4.95 kV is measured for the modified device which shows ~20% improvement of the termination efficiency for no extra cost or extra process step. Equal-size BJTs by interdigitated-emitter with different number of fingers and cell pitches were fabricated. The maximum current gain of 40 is achieved for a single finger device with the emitter width of 40 μm at IC = 0.25 A (JC = 310 A/cm2) which corresponds to RON = 33 mΩ.cm2. It is presented that the current gain decreases by having more fingers while the maximum current gain is achieved at higher current density.

  • 125.
    Elgammal, Karim
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Hugosson, Håkan W.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Smith, Anderson D.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Råsander, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF.
    Bergqvist, Lars
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Centra, SeRC - Swedish e-Science Research Centre.
    Delin, Anna
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Materialfysik, MF. KTH, Centra, SeRC - Swedish e-Science Research Centre. Uppsala University.
    Density functional theory calculations of graphene-based humidity and carbon dioxide sensors: effect of silica and sapphire substratesManuskript (preprint) (Övrigt vetenskapligt)
  • 126.
    Esteve, Romain
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fabrication and Characterization of 3C- and4H-SiC MOSFETs2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    During the last decades, a global effort has been started towards the implementation of energy efficient electronics. Silicon carbide (SiC), a wide band-gap semiconductor is one of the potential candidates to replace the widespread silicon (Si) which enabled and dominates today’s world of electronics. It has been demonstrated that devices based on SiC lead to a drastic reduction of energy losses in electronic systems. This will help to limit the global energy consumption and the introduction of renewable energy generation systems to a competitive price.

    Active research has been dedicated to SiC since the 1980’s. As a result, a mature SiC growth technology has been developed and 4 inch SiC wafers are today commercially available. Research and development activities on the fabrication of SiC devices have also been carried out and resulted in the commercialization of SiC devices. In 2011, Schottky barrier diodes, bipolar junction transistors, and junction field effect transistors can be purchased from several electronic component manufacturers.

    However, the device mostly used in electronics, the metal-oxide-semiconductor field effect transistor (MOSFET) is only recently commercially available in SiC. This delay is due to critical technology issues related to reliability and stability of the device, which still challenge many researchers all over the world.

    This thesis summarizes the main challenges of the SiC MOSFET fabrication process. State of the art technology modules like the gate stack formation, the drain/source ohmic contact formation, and the passivation layer deposition are considered and contributions of this work to the development of these technology modules is reported.

    The investigated technology modules are integrated into the complete fabrication process of vertical MOSFET devices. This MOSFET process was tested using cubic SiC (3C-SiC) and hexagonal SiC (4H-SiC) wafers and achieved results will be discussed.

  • 127.
    Esteve, Romain
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Reshano, S.A.
    Savage, S.
    Bakowski, M.
    Kaplan, W.
    Persson, S.
    Schöner, A.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Toward 4H-SiC MISFETs Devices Based on ONO (SiO2-Si3N4-SiO2) Structures2011Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 5, nr 158, s. 496-501Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrical properties of metal-insulator-semiconductor (MIS) devices based on ONO (SiO2-Si3N4-SiO2) structures fabricatedon n-type 4H-SiC (0001) epilayers have been investigated. Three different combinations of low-pressure chemical vapordeposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD) and thermal oxidations (TO) in N2O and wet oxygenH2O:O2 were studied for the formation of the ONO stack. In addition, the influence of the thickness of SiO2and Si3N4 layers were considered and recommendations for optimal ONO structure are given. Oxide characterization tests and reliability investigations have been performed at room and high temperatures. This comparative study resulted in the development of ONO structuresdescribing low oxide/near interface/interface defects and high reliability of the devices even at high temperature.

  • 128.
    Esteve, Romain
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Schöner, A.
    Reshanov, S.A.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Comparative study of thermal oxides and post-oxidized depositedoxides on n-type free standing 3C-SiC2010Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 645-648, s. 829-832Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrical properties of oxides fabricated on n-type 3C-SiC (001) using wet oxidationand an advanced oxidation process combining SiO 2 deposition with rapid post oxidation steps havebeen compared. Two alternative SiO 2 deposition techniques have been studied: the plasmaenhanced chemical vapor deposition (PECVD) and the low pressure chemical vapor deposition(LPCVD). The post-oxidized PECVD oxide is been demonstrated to be beneficial in terms ofinterface traps density and reliability.

  • 129.
    Esteve, Romain
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Schöner, A.
    Reshanov, S.A.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Optimization of Poly-Silicon Process for 3C-SiC Based MOS Devices2010Ingår i: Material Research Society Symposium Proceedings, 2010, s. 115-Konferensbidrag (Refereegranskat)
  • 130. Fan, W.
    et al.
    Zhao, D.
    Chuwongin, S.
    Seo, J. -H
    Yang, H.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ma, Z.
    Zhou, W.
    Electrically-pumped membrane-reflector surface-emitters on silicon2013Ingår i: 2013 IEEE Photonics Society Summer Topical Meeting Series, PSSTMS 2013, IEEE , 2013, s. 19-20Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report here electrically-pumped membrane reflector surface-emitters on silicon based on transferred InGaAsP QW structures sandwiched in between two single-layer Fano resonance photonic crystal membrane reflectors on silicon substrate.

  • 131. Fan, W.
    et al.
    Zhao, D.
    Chuwongin, S.
    Seo, J. -H
    Yang, H.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ma, Z.
    Zhou, W.
    Fabrication of electrically-pumped resonance-cavity membrane-reflector surface-emitters on silicon2013Ingår i: 2013 IEEE Photonics Conference (IPC), 2013, s. 643-644Konferensbidrag (Refereegranskat)
    Abstract [en]

    Various lasers and light sources on Si via heterogeneous integration of Si/III-V have been reported based on direct growth on Si [1] or wafer bonding technology [2-4]. We reported earlier optically-pumped Si membrane-reflector vertical-cavity surface-emitting lasers (MRVCSELs) fabricated by low-temperature membrane transfer printing processes [5, 6]. Here we report electrically-pumped devices based on an intra-cavity contact configuration.

  • 132.
    Farese, Luca
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Experimental Study of Degradation in 4H-SiC BJTs by Means of Electrical Characterization and Electroluminescence2010Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2009 / [ed] Bauer AJ; Friedrichs P; Krieger M; Pensl G; Rupp R; Seyller T, 2010, Vol. 645-648, s. 1037-1040Konferensbidrag (Refereegranskat)
    Abstract [en]

    SiC power bipolar junction transistors (BJTs), for high voltage applications, have been studied under elevated temperature and electrical stress conditions. Electroluminescence has been used to capture effects of defect motion and growth, in complete transistor structures, leading to a quantifiable degradation in the electrical performance. The observed degradation of current gain (beta) and on-resistance (RON) was relatively modest and saturated after a limited stress time, resulting in stable device performance. The characteristic wavelength (450 nm) of the electroluminescence, or light emission, in the visual and near infrared (NIR) range, coupled to the shape of the defects indicates that basal plane dislocations and stacking faults are involved.

  • 133. Fashandi, H.
    et al.
    Andersson, M.
    Eriksson, J.
    Lu, J.
    Smedfors, Katarina
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Spetz, A. Lloyd
    Eklund, P.
    Single-step synthesis process of Ti3SiC2 ohmic contacts on 4H-SiC by sputter-deposition of Ti2015Ingår i: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 99, s. 53-56Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report a single-step procedure for growth of ohmic Ti3SiC2 on 4H-SiC by sputter-deposition of Ti at 960 degrees C, based on the Ti-SiC solid-state reaction during deposition. X-ray diffraction and electron microscopy show the growth of interfacial Ti3SiC2. The as-deposited contacts are ohmic, in contrast to multistep processes with deposition followed by rapid thermal annealing. This procedure also offers the possibility of direct synthesis of oxygen-barrier capping layers before exposure to air, potentially improving contact stability in high-temperature and high-power devices.

  • 134. Feste, S. F.
    et al.
    Zhang, M.
    Knoch, J.
    Zhang, Shi-Li
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Mantl, S.
    Variability in SOI Schottky barrier MOSFETs2008Ingår i: ULIS - Int. Conf. ULtim. Integr. Silicon, 2008, s. 27-30Konferensbidrag (Refereegranskat)
    Abstract [en]

    We study the variability of the electrical characteristics of silicon-on-insulator (SOI) SB-MOSFETs. A new method by extracting the variation of the threshold voltage from a large number of devices with different SOI thicknesses enables determining the main sources of variability and distinguishing between them. It is found that the device-to-device variability is mainly due to the inherent variation of the Schottky barrier (SB) height. An additional but smaller contribution stems from fluctuations of the SOI body thickness itself. However, scaling the SOI thickness down our measurements suggest that the SB inhomogeneity increases with decreasing tsi. Furthermore, employing dopant segregation during silicidation to realize low SB heights leads to an increase of the variability, too. Using the measured spread of ΦB we discuss on the base of simulations the influence of this variation on the on-current of SB-MOSFETs. The improved electrostatic gate control in multi-gate devices reduces the sensitivity of carrier injection on an inhomogeneous ΦB and thus suppresses the variability.

  • 135.
    Fischer, Andreas C.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Belova, Lyubov M.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Malm, Gunnar B.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kolahdouz, Mohammadreza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Gylfason, Kristinn B.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Stemme, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik.
    3D Free-Form Patterning of Silicon by Ion Implantation, Silicon Deposition, and Selective Silicon Etching2012Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 22, nr 19, s. 4004-4008Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method for additive layer-by-layer fabrication of arbitrarily shaped 3D silicon micro- and nanostructures is reported. The fabrication is based on alternating steps of chemical vapor deposition of silicon and local implantation of gallium ions by focused ion beam (FIB) writing. In a final step, the defined 3D structures are formed by etching the silicon in potassium hydroxide (KOH), in which the local ion implantation provides the etching selectivity. The method is demonstrated by fabricating 3D structures made of two and three silicon layers, including suspended beams that are 40 nm thick, 500 nm wide, and 4 μm long, and patterned lines that are 33 nm wide.

  • 136.
    Fischer, Andreas C.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Gylfason, Kristinn B.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Belova, Liubov M.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik.
    Malm, Gunnar B.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kolahdouz, Mohammadreza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rikers, Yuri G.M.
    FEI Electron Optics.
    Stemme, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    3D Patterning of Si Micro and Nano Structures by Focused Ion Beam Implantation, Si Deposition and Selective Si Etching2012Konferensbidrag (Övrigt vetenskapligt)
  • 137.
    Fischer, Andreas C.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Gylfason, Kristinn B.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Belova, Lyubov M.
    Malm, Gunnar B.
    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.
    Kolahdouz, M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rikers, Y. G. M.
    Stemme, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Layer-by-layer 3D printing of Si micro- and nanostructures by Si deposition, ion implantation and selective Si etching2012Ingår i: 12th IEEE Conference on Nanotechnology (IEEE-NANO), 2012, IEEE conference proceedings, 2012, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we report a method for layer-by-layer printing of three-dimensional (3D) silicon (Si) micro- and nanostructures. This fabrication method is based on a sequence of alternating steps of chemical vapor deposition of Si and local implantation of gallium (Ga+) ions by focused ion beam (FIB) writing. The defined 3D structures are formed in a final step by selectively wet etching the non-implanted Si in potassium hydroxide (KOH). We demonstrate the viability of the method by fabricating 2 and 3-layer 3D Si structures, including suspended beams and patterned lines with dimensions on the nm-scale.

  • 138.
    Garcia, Julian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Digitally Enhanced Continuous-Time Sigma-Delta Analogue-to-Digital Converters2012Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The continuous downscaling of CMOS technology presents advantagesand difficulties for IC design. While it allows faster, denser and more energy efficient digital circuits, it also imposes several challenges which limit the performance of analogue circuits. Concurrently, applications are continuously pushing the boundaries of power efficiency and throughput of electronic systems. Accordingly, IC design is increasingly shifting into highly digital systems with few necessary analogue components. Particularly, continuous-time (CT) sigma-delta (ΣΔ) analogue-to-digital converters (ADCs) have recently received a growing interest, covering high-resolution medium-speed requirementsor offering low power alternatives to low speed applications. However, there are still several aspects that deserve further investigation so as to enhancethe ADC’s performance and functionality. The objective of the research performed in this thesis is the investigation of digital enhancement solutions for CT ΣΔ ADCs. In particular, two aspects are considered in this work.

    First, highly digital techniques are investigated to minimize circuit impairments, with the objective of providing solutions with reduced analogue content. In this regard, a multi-bit CT ΣΔ modulator with reduced number of feedback levels is explored to minimize the use of linearisation techniques in the DAC. The proposed architecture is designed and validated through behavioural simulations targeting a mobile application. Additionally, a novel self-calibration technique, using test-signal injection and digital cancellation, is proposed to counteract process variations affecting single loop CT implementations. The effectiveness of the calibration technique is confirmed through corner simulations using behavioural models and shows that stability issues are minimized and that a 7 dB SNDR degradation can be avoided.

    The second aspect of this thesis investigates the use of high order CT modulators in incremental ΣΔ (IΣΔ) and extended-range IΣΔ ADCs, with the objective of offering low-power alternatives for low-speed high-resolution multi-channel applications. First, a 3rd order single loop CT IΣΔ ADC, targeting an 8-channel 500 Ksamples/sec rate per channel recording system for neuropotential sensors, is proposed, fabricated and tested. The proposed architecture lays the theoretical groundwork and demonstrates a competitive performance of high-order CT IΣΔ ADCs for low-power multi-channel applications. The ADC achieves 65.3 dB/64 dB SNR/SNDR and 68.2 dB dynamic range. The modulator consumes 96 μW from a 1.6 V power supply. Additionally, the use of extended range approach in CT IΣΔ ADCs is investigated,so as to reduce the required number of cycles per conversion while benefiting from the advantages of a CT implementation. The operation, influence of filter topology and impact of circuit non-idealities are first analysed using a general approach and later validated through a test-case. It was found that, by applying analogue-digital compensation in the digital domain, it is possible to minimize the noise leakage due to analogue-digital transfer function mismatches and benefit from relaxed amplifiers’ finite gain-bandwidth product and finite DC gain, allowing, as a consequence, a power conscious alternative.

  • 139.
    Garcia, Julian
    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 Low-Power CT Incremental 3rd Order Sigma Delta ADC for Biosensor Applications2013Ingår i: IEEE Transactions on Circuits and Systems. Part 1: Regular Papers, ISSN 1549-8328, Vol. 60, nr 1, s. 25-36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper proposes a 3rd order single-loop continuous-time incremental sigma-delta analogue-to-digital converter (ADC) for time-multiplexed signals. Incremental sigma-delta modulation is used to address medium to high resolution requirements of multi-channel applications, while a 3rd order continuous-time implementation is investigated as an alternative for low-power solutions. A prototype of the proposed modulator, running at 320 kHz, has been fabricated in a 0.15- mCMOStechnology,while the synchronization circuitry to allow incremental operation was built on-board. Measurement results show that the ADC achieves 65.3 dB peak SNR, 64 dB peak SNDR and 68.2 dB dynamic range over a 2 kHz bandwidth. The modulator’s power dissipation is 96 W from a 1.6 V power supply. This translates into the best figure-ofmerit when compared to recently published continuous-time alternatives, while being competitive with respect to state-of-the-art discrete-time counterparts.

  • 140.
    Garcia, Julian
    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.
    On Continuous-Time Incremental Sigma Delta ADCs With Extended Range2013Ingår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 62, nr 1, s. 60-70Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, the use of continuous-time implementation in extended-range (ER) incremental sigma-delta analog-to-digital converters is analyzed in order to explore a possible solution to low-power multichannel applications. The operation principle, possible loop filter topologies, and critical issues are considered using a general approach. It is demonstrated that, in order to fully benefit from ER, careful attention has to be paid to the analog-digital transfer function mismatches. A third-order single-bit topology validates the theoretical analysis. Its performance is evaluated while the impact of key circuit nonidealities is quantified through behavioral-level simulations. It is shown that, by applying analog-digital mismatch compensation in the digital domain, it is possible to relax the amplifiers' finite gain-bandwidth product and finite dc gain requirements, thus allowing a power-conscious alternative.

  • 141.
    Garcia, Julian
    et al.
    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 Extended-Range Incremental CT Sigma Delta ADC with Optimized Digital Filter2012Ingår i: 2012 13th International Symposium On Quality Electronic Design (ISQED), IEEE , 2012, s. 179-184Konferensbidrag (Refereegranskat)
    Abstract [en]

    Extended range approach has been employed in discrete-time incremental sigma-delta analog-to-digital converters to reduce the number of cycles per conversion and therefore the power dissipation. In this work, extended range is combined with continuous-time filter implementation so as to reduce the integrators gain-bandwidth product requirement. The proposed architecture and mathematical analysis are presented using a 3rd order single-loop single-bit sigma-delta modulator as proof-of-concept. In order to overcome the analog-digital transfer functions mismatches, an appropriate digital filter is designed using optimization tools. Behavioral simulations show that the proposed architecture with an optimized filter achieves 13.8 bits resolution with a 4 kSamples/sec sampling rate to comply with a high-resolution biomedical application.

  • 142.
    Garcia, Julian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Built-in self calibration for process variation in single-loop continuous-time sigma-delta modulators2010Ingår i: 17th IEEE International Conference on Electronics, Circuits, and Systems (ICECS), 2010, IEEE conference proceedings, 2010, s. 1136-1139Konferensbidrag (Refereegranskat)
    Abstract [en]

    A novel built-in self calibration technique for single-loop continuous-time sigma-delta modulators is proposed. Using out-of-band test signal injection and digital cancellation, this technique provides an area efficient, highly digital calibration structure to counteract gain variations in the loop filter. The calibration methodology and mathematical analysis are presented using a 2 nd order multibit sigma-delta modulator as a proof of concept. The effect of the finite gain-bandwidth of amplifiers is included when evaluating the calibration method. The proposed technique is validated through corner simulations using behavioral models and it shows that degradation in the signal-to-noise-plus-distortion ratio can be counteracted.

  • 143.
    Garcia-Carrasco, Alvaro
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Petersson, Per
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Grzonka, J.
    Gilbert, M. R.
    Fortuna-Zalesna, E.
    Rubel, Marek
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Impact of helium implantation and ion-induced damage on reflectivity of molybdenum mirrors2016Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Molybdenum mirrors were irradiated with Mo and He ions to simulate the effect of neutron irradiation on diagnostic first mirrors in next-generation fusion devices. Up to 30 dpa were produced under molybdenum irradiation leading to a slight decrease of reflectivity in the near infrared range. After 3×1017 cm-2 of helium irradiation, reflectivity decreased by up to 20%. Combined irradiation by helium and molybdenum led to similar effects on reflectivity as irradiation with helium alone. Ion beam analysis showed that only 7% of the implanted helium was retained in the first 40nm layer of the mirror. The structure of the near-surface layer after irradiation was studied with scanning transmission electron microscopy and the extent and size distribution of helium bubbles was documented. The consequences of ion-induced damage on the performance of diagnostic components are discussed.

  • 144.
    García, Julian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    High-order continuous-time incremental ΣΔ ADC for multi-channel applications2011Ingår i: IEEE International Symposium of Circuits and Systems, ISCAS 2011, IEEE conference proceedings, 2011, s. 1121-1124Konferensbidrag (Refereegranskat)
    Abstract [en]

    A novel high-order single-loop incremental sigma-delta ADC for multi-channel applications is proposed. High-order continuous-time architectures are explored using a 3rd order single-bit modulator as a test-case. The performance of the proposed architecture, taking into account critical non-idealities, is analyzed and its advantages and issues are discussed. Behavioral simulations show a key advantage regarding the integrators' gain-bandwidth requirement of the proposed ADC compared to discrete-time counterparts. This advantage leads to possible low power solutions for multi-channel applications.

  • 145.
    García, Julian
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Multibit continuous-time ΣΔ modulator with reduced number of feedback levels2010Ingår i: 6th Conference on Ph.D. Research in Microelectronics and Electronics, PRIME 2010, IEEE conference proceedings, 2010, s. 1-4Konferensbidrag (Refereegranskat)
    Abstract [en]

    A multibit continuous-time sigma-delta modulator, where truncation error shaping and cancellation techniques are applied, is proposed. These techniques are proposed in order to reduce the number of levels in the feedback digital-to-analogue converters and then eliminate the use of linearization techniques. Mathematical analysis, advantages and obstacles are discussed when two different coding schemes are employed in the 1st feedback digital-to-analogue converter of the continuous-time sigma-delta modulator. The proposed architecture is designed and simulated considering a wireless mobile application.

  • 146.
    Garidis, Konstantinos
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Jayakumar, Ganesh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Asadollahi, Ali
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Dentoni Litta, Eugenio
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Characterization of bonding surface and electrical insulation properties of inter layer dielectrics for 3D monolithic integration2015Ingår i: EUROSOI-ULIS 2015 - 2015 Joint International EUROSOI Workshop and International Conference on Ultimate Integration on Silicon, 2015, s. 165-168Konferensbidrag (Refereegranskat)
    Abstract [en]

    We investigate the bonding and electrical insulation properties of oxide layers for use in 3D monolithic integration via direct wafer bonding. Low surface roughness layers deposited on 100 mm Si wafers by atomic layer deposition (ALD) at 200 °C-350 °C, provide with adequate layer transfer bonding interfaces. Wafer scale IV measurements were performed to investigate the leakage current. We demonstrate that ALD oxide can function as a reliable bonding surface and also exhibit leakage current values below the nA range. Both properties are important pillars for a successful 3D monolithic integration.

  • 147.
    Garidis, Konstantinos
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Pret, A. V.
    Gronheid, R.
    Mask roughness impact on extreme UV and 193 nm immersion lithography2012Ingår i: Microelectronic Engineering, ISSN 0167-9317, E-ISSN 1873-5568, Vol. 98, s. 138-141Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The contribution of mask absorber line edge roughness on printed resist lines is studied for extreme UV and 193 nm immersion lithography. Programmed roughness modules were designed for roughness transfer function evaluation on 88 nm pitch line space patterns. The tested modules were designed applying variations of roughness amplitude and spatial frequency. Power spectral density analysis was performed on top-down SEM images. The effect of frequency roughness filtering by the lithographic optical system was studied with different illumination settings. It was found that, except for the degradation of the aerial image due to the filtering effect, less performing illuminations show an increased deterioration of the aerial image quality and thus contribute further to line edge roughness. A comparison with previous work was completed on different mask architectures and photoresist platforms. Resist performance can attenuate the roughness transfer from mask but at the cost of worse chemical gradient at the edges of the exposed regions.

  • 148.
    Ghandi, Reza
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fabrication Technology for Efficient High Power Silicon Carbide Bipolar Junction Transistors2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The superior characteristics of Silicon Carbide as a wide band gap semiconductor have motivated many industrial and non-industrial research groups to consider SiC for the next generations of high power semiconductor devices. The SiC Bipolar Junction Transistor (BJT) is one candidate for high power applications due to its low on-state power loss and fast switching capability. However, to compete with other switching devices such as Field Effect Transistors (FETs) or IGBTs, it is necessary for a power SiC BJT to provide a high current gain to reduce the power required from the drive circuit. In this thesis implantation free 4H-SiC BJTs with linearly graded base layer have been demonstrated with common-emitter current gain of 50 and open-base breakdown voltage of 2700 V. Also an efficient junction termination extension (JTE) with 80% of theoretical parallel-plane breakdown voltage was analyzed by fabrication of high voltage PiN diodes to achieve an optimum dose of remaining JTE charge. Surface passivation of 4H-SiC BJT is an essential factor for efficient power BJTs. Therefore different passivation techniques were compared and showed that around 60% higher maximum current gain can be achieved by a newsurface passivation layer with low interface trap density that consists of PECVD oxide followed by post-deposition oxide anneal in N2O ambient. This surface passivation along with doublezone JTE were used for fabrication of high power BJTs that result in successful demonstration of 2800 V breakdown voltage for small area (0.3 × 0.3 mm) and large area (1.8 × 1.8 mm) BJTs with a maximum dc current gain of 55 and 52, respectively. The small area BJT showed RON = 4mΩcm2, while for the large are BJT RON = 6.8 mΩcm2. Finally, a Darlington transistor with a maximum current gain of 2900 at room temperature and 640 at 200 °C is reported. The high current gain of the Darlington transistor is achieved by optimum design for the ratio of the active area of the driver BJT to the output BJT.

  • 149.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Buono, Benedetto
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Esteve, Romain
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Schöner, Adolf
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Han, Jisheng
    Dimitrijev, Sima
    Reshanov, Sergey A.
    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.
    Surface-passivation effects on the performance of 4H-SiC BJTs2011Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 58, s. 259-265Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this brief, the electrical performance in terms of maximum current gain and breakdown voltage is compared experimentally and by device simulation for 4H-SiC BJTs passivated with different surface-passivation layers. Variation in bipolar junction transistor (BJT) performance has been correlated to densities of interface traps and fixed oxide charge, as evaluated through MOS capacitors. Six different methods were used to fabricate SiO2 surface passivation on BJT samples from the same wafer. The highest current gain was obtained for plasma-deposited SiO2 which was annealed in N2O ambient at 1100 °C for 3 h. Variations in breakdown voltage for different surface passivations were also found, and this was attributed to differences in fixed oxide charge that can affect the optimum dose of the high-voltage junction-termination extension (JTE). The dependence of breakdown voltage on the dose was also evaluated through nonimplanted BJTs with etched JTE.

  • 150.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Buono, Benedetto
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    High-Voltage 4H-SiC PiN Diodes With Etched Junction Termination Extension2009Ingår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 30, nr 11, s. 1170-1172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Implantation-free mesa-etched 4H-SiC PiN diodes with a near-ideal breakdown voltage of 4.3 kV (about 80% of the theoretical value) were fabricated, measured, and analyzed by device simulation and optical imaging measurements at breakdown. The key step in achieving a high breakdown voltage is a controlled etching into the epitaxially grown p-doped anode layer to reach an optimum dopant dose of similar to 1.2 x 10(13) cm(-2) in the junction termination extension (JTE). Electroluminescence revealed a localized avalanche breakdown that is in good agreement with device simulation. A comparison of diodes with single-and double-zone etched JTEs shows a higher breakdown voltage and a less sensitivity to varying processing conditions for diodes with a two-zone JTE.

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