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  • 151.
    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.
    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.
    High Voltage, Low On-resistance 4H-SiC BJTs with Improved Junction Termination Extension2011Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 679-680, s. 706-709Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, implantation-free 4H-SiC bipolar transistors with two-zone etched-JTE and improved surface passivation are fabricated. This design provides a stable open-base breakdown voltage of 2.8 kV which is about 75% of the parallel plane breakdown voltage. The small area devices shows a maximum dc current gain of 55 at Ic=0.33 A (J(C)=825 A/cm(2)) and V-CESAT = 1.05 V at Ic = 0.107 A that corresponds to a low ON-resistance of 4 m Omega.cm(2). The large area device shows a maximum dc current gain of 52 at Ic = 9.36 A (J(C)=312 A/cm(2)) and V-CESAT = 1.14 V at Ic = 5 A that corresponds to an ON-resistance of 6.8 m Omega.cm(2). Also these devices demonstrate a negative temperature coefficient of the current gain (beta=26 at 200 degrees C) and positive temperature coefficient of the ON-resistance (R-ON = 10.2 m Omega.cm(2)).

  • 152.
    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.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    High current-gain implantation-free 4H-SiC Monolithic Darlington Transistor2011Ingår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 32, nr 2, s. 188-190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An implantation-free 4H-SiC Darlington transistor with high current gain of 2900 ( JC= \970A/cm2) and VCE) = 6V) at room temperature is reported. The device demonstrates a record maximum current gain of 640 at 200 hC, offering an attractive solution for high-temperature applications. The monolithic Darlington device exhibits an open-base breakdown voltage of 1 kV that is less than the optimum bulk breakdown due to isolation trench between the driver and the output bipolar junction transistor. On the same wafer, a monolithic Darlington pair with a nonisolated base layer was also fabricated. At room temperature, this device shows a maximum current gain of 1000 and an open-base breakdown voltage of 2.8 kV, which is 75% of the parallel-plane breakdown voltage

  • 153.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Buono, Benedotto
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Shayestehaminzadeh, Seyedmohammad
    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.
    Influence of crystal orientation on the current gain in 4H-SiC BJTs2010Ingår i: Device Research Conference - Conference Digest, DRC, 2010, s. 131-132Konferensbidrag (Refereegranskat)
    Abstract [en]

    The 4H-SiC bipolar junction transistors (BJT) are considered as efficient high power switching devices due to the ability of obtaining very low specific on-resistance compared to FET based devices. However, one drawback with the present high voltage BJTs is the relatively low current gain. To reduce the power required by the drive circuit, it is important to increase the common-emitter current gain ( #x03B2;). 4H-SiC (0001) Si-face has become a favorable plane for vertical power BJTs with epitaxial layers that shows higher mobility along the c-axis and provides higher current gain. Furthermore, important progress on improving the current gain focused on the quality of surface passivation at the SiC/SiO2 interface has been reported during previous years. Higher quality of passivation can provide less interface traps and thereby minimizes the surface recombination current. Conventionally, vertical 4H-SiC BJTs are fabricated along the [11_00] direction on (0001) Si-face. However due to anisotropic properties of 4H-SiC, different orientations on Si-face can also affect the base current of the BJT through variation of mobility and interface traps density distribution along each direction. In this work, single-finger small area BJTs are fabricated on (0001) Si-face along [12_10], [011_0], [112_0] and [11_00] directions. This design can provide various orientations of BJTs that corresponds to an angular range between 0 to 180 degrees relative to conventional [11_00] direction. The goal was to find a correlation between different crystallographic orientation, mobility and interface traps density distribution through transistor characteristics and finally comparison with simulation. Fig.1 shows a cross section and top view of fabricated BJTs. The n+ emitter epi-layer is 1.35 #x03BC;m nitrogen doped to 6 #x00D7;1018 cm-3 and capped by 200-nm-thick 2 #x00D7;1019 cm-3 layer. The base epi-layer is 650 nm Al-d- - oped with concentration of 4.3 #x00D7;1017 cm-3. The drift n- epilayer is 20 #x03BC;m thick and doped to 6 #x00D7;1015 cm-3. Inductively coupled plasma (ICP) etching with an oxide mask was used to form emitter and base mesas. Fig.2 is a comparison of the maximum current gain with different orientations normalized to the maximum current gain along [11_00] before surface passivation and contact metallization. The results indicate that the maximum current gain is orientation-dependent and has a maximum for BJTs with the emitter edge aligned to the [112_0] direction. The variation effect of planar mobility and interface traps concentration on the current gain is simulated based on the previous work and is illustrated in Fig.3. The simulation shows that interface oxide charges has more influence on the current gain compared to the mobility and higher current gain is attributed to lower oxide interface charges. The orientation dependence of the transistor parameters such as maximum current gain after passivation and the base resistance will be evaluated and compared with simulation.

  • 154.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Buono, Benedotto
    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.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Shayestehaminzadeh, Seyedmohammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Removal of Crystal Orientation Effects on the Current Gain of 4H-SiC BJTs Using Surface Passivation2011Ingår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 32, nr 5, s. 596-598Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this letter, the dependence of current gain and base resistance on crystal orientations for single-finger 4H-SiC bipolar junction transistors ( BJTs) is analyzed. Statistical evaluation techniques were also applied to study the effect of surface passivation and mobility on the performance of the devices. It is shown that BJTs with an emitter edge aligned to the [1 (2) under bar 10] direction shows a lower current gain before surface passivation and higher base resistance after contact formation compared with other investigated crystal directions. However, the devices show a similar current gain independent of the crystal orientation after surface passivation.

  • 155.
    Ghandi, Reza
    et al.
    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, R.
    Buono, Benedetto
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Schoner, A.
    Han, J.
    Dimitrijev, S.
    Reshanov, S. A.
    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.
    Experimental evaluation of different passivation layers on the performance of 3kV 4H-SiC BJTs2010Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 645-648, nr Part 1-2, s. 661-664Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, the electrical performance in terms of maximum current gain, ON-resistance and blocking capability has been compared for 4H-SiC BJTs passivated with different surface passivation layers. Variation in 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 PECVD deposited SiO2 which was annealed in N2O ambient at 1100 degrees C during 3 hours. Variations in breakdown voltage for different surface passivations were also found, and this is attributed to differences in fixed oxide charge that can affect the optimum dose of the high voltage JTE termination.

  • 156.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    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.
    Buono, Benedetto
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    High Voltage (2.8 kV) Implantation-free 4H-SiC BJTs with Long-TermStability of the Current Gain2011Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 58, nr 8, s. 2665-2669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, implantation-free 4H-SiC BJTs with high breakdown of 2800 V have been fabricated utilizing acontrolled two-step etched junction termination extension (JTE). The small area devices show a maximum dc current gainof 55 at Ic=0.33 A (JC=825 A/cm2) and VCESAT = 1.05 V at Ic = 0.107 A that corresponds to a low ON-resistance of 4mΩ·cm2. The large area device have a maximum dc current gain of 52 at Ic = 9.36 A (JC=289 A/cm2) and VCESAT = 1.14 Vat Ic = 5 A that corresponds to an ON-resistance of 6.8 mΩ·cm2. Also these devices demonstrate a negative temperaturecoefficient of the current gain (β=26 at 200°C) and a positive temperature coefficient of the ON-resistance (RON = 10.2mΩ·cm2 at 200°C). The small area BJT shows no bipolar degradation and low current gain degradation after 150 Hrs stressof the base-emitter diode with current level of 0.2A (JE=500 A/cm2). Also, large area BJT shows a VCE fall time of 18 nsduring turn-on and a VCE rise time of 10 ns during turn-off for 400 V switching characteristics.

  • 157.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lee, Hyung-Seok
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Domeij, Martin
    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.
    Implantation-Free Low on-resistance 4H-SiC BJTs with Common-Emitter Current Gain of 50 and High Blocking Capability2009Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 615-617, s. 833-836Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, high voltage blocking (2.7 kV) implantation-free SiC Bipolar Junction Transistors with low on-state resistance (12 m Omega-cm(2)) and high common-emitter current gain of 50 have been fabricated. A graded base doping was implemented to provide a low resistive ohmic contact to the epitaxial base. This design features a fully depleted base layer close to the breakdown voltage providing an efficient epitaxial JTE without ion implantation. Eliminating all ion implantation steps in this approach is beneficial for avoiding high temperature dopant activation annealing and for avoiding generation of life-time killing defects that reduces the current gain. Also in this process large area transistors showed common-emitter current gain of 38 and open-base breakdown voltage of 2 kV.

  • 158.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lee, Hyung-Seok
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Domeij, Martin
    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.
    Fabrication of 2700-v 12-m Omega center dot cm(2) non ion-implanted 4H-SiC BJTs with common-emitter current gain of 502008Ingår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 29, nr 10, s. 1135-1137Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-voltage blocking (2.7-kV) implantation-free SiC bipolar junction transistors with low ON-state resistance (12 m Omega . cm(2)) and high common-emitter current gain of 50 have been fabricated. A graded-base doping was implemented to provide a low-resistive ohmic contact to the epitaxial base. This design features a fully depleted base layer close to the breakdown voltage providing an efficient epitaxial JTE without ion implantation. Eliminating all ion implantation steps in this approach is beneficial for avoiding high-temperature dopant activation annealing and for avoiding generation of lifetime-killing defects that reduce the current gain.

  • 159.
    Ghandi, Reza
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lee, Hyung-Seok
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Domeij, Martin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Zetterling, Carl-Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ostling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Simultaneous study of nickel based ohmic contacts to Si-face and C-face of n-type silicon carbide2007Ingår i: 2007 INTERNATIONAL SEMICONDUCTOR DEVICE RESEARCH SYMPOSIUM, VOLS 1 AND 2, NEW YORK: IEEE , 2007, s. 311-311Konferensbidrag (Refereegranskat)
  • 160. Ghany, M. A. A. E.
    et al.
    Reehal, G.
    Korzec, D.
    Ismail, Mohammed
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. Ohio State University, Columbus, United States .
    Power analysis for Asynchronous CLICH Network-on-Chip2010Ingår i: Proceedings - IEEE International SOC Conference, SOCC 2010, IEEE , 2010, s. 499-504Konferensbidrag (Refereegranskat)
    Abstract [en]

    Asynchronous Chip-Level Integration of Communicating Heterogeneous Elements (CLICH) architecture is proposed to achieve low power Network-on-Chip (NoC). Asynchronous design could reduce the power dissipation of the network if the activity factor of the data transfer between two switches ( data satisfies a certain condition. The area of Asynchronous CLICH switch is increased by 25% as compared to the Synchronous switch. However, the power dissipation of the Asynchronous architecture could be decreased by 21% as compared to the power dissipation in the conventional Synchronous architecture when the ( data equals 0.2 and the activity factor of the control signals is equal to 1 over 64 of the ( data. The total metal resources required to implement Asynchronous design is decreased by 7%.

  • 161.
    Gisdakis, Stylianos
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Manolopoulos, Vasileios
    KTH.
    Tao, Sha
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Rusu, Ana
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Papadimitratos, Panagiotis
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Secure and Privacy-Preserving Smartphone based Traffic Information Systems2015Ingår i: IEEE transactions on intelligent transportation systems (Print), ISSN 1524-9050, E-ISSN 1558-0016, Vol. 16, nr 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Increasing smartphone penetration, combined with the wide coverage of cellular infrastructures, renders smartphone-based traffic information systems (TISs) an attractive option. The main purpose of such systems is to alleviate traffic congestion that exists in every major city. Nevertheless, to reap the benefits of smartphone-based TISs, we need to ensure their security and privacy and their effectiveness (e.g., accuracy). This is the motivation of this paper: We leverage state-of-the-art cryptographic schemes and readily available telecommunication infrastructure. We present a comprehensive solution for smartphone-based traffic estimation that is proven to be secure and privacy preserving. We provide a full-blown implementation on actual smartphones, along with an extensive assessment of its accuracy and efficiency. Our results confirm that smartphone-based TISs can offer accurate traffic state estimation while being secure and privacy preserving.

  • 162.
    Grimaldi, Rocco
    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 10-bit 5kHz level-crossing ADC2011Ingår i: 2011 20th European Conference on Circuit Theory and Design, ECCTD 2011, 2011, s. 564-567Konferensbidrag (Refereegranskat)
  • 163.
    Grishin, A. M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Khartsev, S. I.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Bohlmark, J.
    Ahlgren, M.
    Ultra-hard AlMgB14 Coatings Fabricated by RF Magnetron Sputtering from a Stoichiometric Target2015Ingår i: JETP Letters: Journal of Experimental And Theoretical Physics Letters, ISSN 0021-3640, E-ISSN 1090-6487, Vol. 100, nr 10, s. 680-687Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For the first time hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric ceramic AlMgB14 target. Optimized processing conditions (substrate temperature, target sputtering power and target-to-substrate distance) enable fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young's modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 and 275 GPa at 200 nm depth in 2 mu m thick film.

  • 164.
    Grishin, Alexander
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. INMATECH Intelligent Materials Technology, Sweden; Petrozavodsk State University, Russia.
    Abrasion resistant low friction and ultra-hard magnetron sputtered AlMgB14 coatings2016Ingår i: Materials Research Express, ISSN 2053-1591, Vol. 3, nr 4, artikel-id 046402Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric AlMgB14 ceramic target. X-ray amorphous AlMgB14 films are very smooth. Their roughness does not exceed the roughness of Si wafer and Corning glass used as the substrates. Dispersion of refractive index and extinction coefficient were determined within 300 to 2500 nm range for the film deposited onto Corning glass. Stoichiometric in-depth compositionally homogeneous 2 μm thick films on the Si(100) wafer possess the peak values of nanohardness 88 GPa and Young’s modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 GPa and 275 GPa at 200 nm depth. Friction coefficient was found to be 0.06. The coating scratch adhesion strength of 14 N was obtained as the first chipping of the coating whereas its spallation failure happened at 21 N. These critical loads and the work of adhesion, estimated as high as 18.4 J m−2, surpass characteristics of diamond like carbon films deposited onto tungsten carbide–cobalt (WC– Co) substrates.

  • 165.
    Grishin, Alexander M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. Petrozavodsk State University, Russian Federation .
    Jalalian, Abolfazl
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar. INMATECH Intelligent Materials Technology, Sweden.
    Tsindlekht, M. I.
    Gadolinia nanofibers as a multimodal bioimaging and potential radiation therapy agent2015Ingår i: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 5, nr 5, artikel-id 057104Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Continuous bead-free C-type cubic gadolinium oxide (Gd2O3) nanofibers 20-30 mu m long and 40-100 nm in diameter were sintered by sol-gel calcination assisted electrospinning technique. Dipole-dipole interaction of neighboring Gd3+ ions in nanofibers with large length-to-diameter aspect ratio results in some kind of superparamagnetic behavior: fibers are magnetized twice stronger than Gd2O3 powder. Being compared with commercial Gd-DTPA/Magnevist (R), Gd2O3 diethyleneglycol-coated (Gd2O3-DEG) fibers show high 1/T-1 and 1/T-2 proton relaxivities. Intense room temperature photoluminescence, high NMR relaxivity and high neutron scattering cross-section of Gd-157 nucleus promise to integrate Gd2O3 fibers for multimodal bioimaging and neutron capture therapy.

  • 166.
    Grishin, Alexander M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Khartsev, Sergey I.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Luminescence in epitaxial Er-doped LiNbO3 films2012Ingår i: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 37, nr 3, s. 419-421Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Epitaxial Er-doped LiNbO3 films were pulsed-laser-deposited onto c-cut sapphire. Wavelength dispersion of the refractive index and the extinction coefficient was obtained by fitting the experimental transmittance spectrum to the Swanepoel formula and microscopic theory, which accounts for two resonance transitions in the electric dipole approximation. Strong room temperature luminescence was observed under 514.5 nm Ar-laser pumping. Two-lifetime (3.0 and 6.0 ms) luminescent decay is characteristic for the lasing I-4(13/2) -> I-4(15/2) transition in Er:LiNbO3 films.

  • 167.
    Grishin, Alexander M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Khartsev, Sergiy I.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Green and blue magneto-optical photonic crystals2012Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 520, nr 9, s. 3647-3650Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A series of one-dimensional heteroepitaxial all-garnet magneto-optical photonic crystals (MOPCs) were pulsed laser deposited to operate at 550 and 470 nm wavelength. We explored the concept of blue shift of the optical absorption edge of ferric ions by substituting Fe with Ga on the tetrahedral sites as well as Bi and Y, respectively, with Ca and Ce at the dodecahedral coordinated positions. 17-layered [Y2Ce1Fe5O12/Gd3Ga5O12] MOPC with a total thickness of 968 nm demonstrates superior magneto-optical performance: Faraday rotation theta(Fmax) = + 2.0 degrees and transmittance as high as 0.35 at the resonance wavelength of 470 nm.

  • 168.
    Grishin, Alexander M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Khartsev, Sergiy I.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Luminescent Magneto-Optical Photonic Crystals2012Ingår i: ASIA-PACIFIC INTERDISCIPLINARY RESEARCH CONFERENCE 2011 (AP-IRC 2011), 2012, s. 012007-Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    We compare luminescent properties of several Er-doped garnet films as building blocks in all-garnet heteroepitaxial magneto-optical photonic crystals: La3Ga5O12, Gd3Ga5O12, Y3Fe5O12, Bi3Fe5O12, and Bi2.97Er0.03Fe4Al0.5Ga0.5O12. Er substituents on the dodecahedral lattice sites do not decrease giant Faraday rotation in Bi3Fe5O12 garnet; meanwhile providing intense room temperature C-band photoluminescence (PL). Fe3+ ion works as a sensitizer for Er resulting in fivefold PL enhancement in iron garnets compared to gallium ones. PL lifetime in gallium garnets is in millisecond range reaching 6 ms in Gd2.9Er0.1Ga5O12. The first luminescent one-dimensional heteroepitaxial all-garnet magneto-optical (MO) photonic crystal was composed from diamagnetic Sm3Ga5O12 and MO-active Bi2.97Er0.03Fe4Al0.5Ga0.5O12 garnet layers by rf-magnetron sputtering on Gd3Ga5O12(111) substrate. Substitution of ferric ions by aluminum and gallium improved transparency and induced perpendicular anisotropy in pure Bi3Fe5O12. Photonic crystals owned a record high magneto-optical quality and a latching type (magnetic remnant) Faraday rotation (FR). At the resonance wavelength 775 nm, specific FR theta(F) = -14.1 deg/mu m and MO-quality factor Q = 99.3 deg represent the highest MO performance achieved so far. Long-lived near-IR luminescence in Er substituted gallium and iron garnet layers used both as Bragg mirrors and microcavities promises magneto-optical photonic crystals to become an active lasing medium.

  • 169.
    Grishin, Alexander M.
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Velichko, A. A.
    Jalalian, Abolfazl
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Nb2O5 nanofiber memristor2013Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 103, nr 5, s. 053111-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Non-woven bead-free 100 mu m long and 80-200 nm in diameter highly crystalline orthorhombic T-Nb2O5 nanofibers were sintered by sol-gel assisted electrospinning technique. Electrical and dielectric spectroscopy tests of individual fibers clamped onto Pt coated Si substrate were performed using a spreading resistance mode of atomic force microscope. Reproducible resistive switching with ON-OFF resistance ratio as high as 2 x 10(4) has a bipolar character, starts with a threshold voltage of 0.8-1.7 V, and follows by continuous growth of conductivity. Resistive memory effect is associated with a voltage-driven accumulation/depletion of oxygen vacancies at Nb2O5/Pt cathode interface. Poole-Frenkel emission from the electronic states trapped at reduced NbOx complexes determines a shape of Nb2O5/Pt diode I-V characteristics. Simple thermodynamic model explains a threshold character of switching, relates experimentally observed characteristics in low and high resistive states, and gives a reasonable estimate of the concentration of oxygen vacancies.

  • 170. Grivickas, V.
    et al.
    Gulbinas, K.
    Jokubaviius, V.
    Sun, J. W.
    Karalinas, M.
    Kamiyama, S.
    Linnarsson, Margareta
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Kaiser, M.
    Wellmann, P.
    Syväjärvi, M.
    Carrier lifetimes and influence of in-grown defects in N-B Co-doped 6H-SiC2014Ingår i: IOP Conference Series: Materials Science and Engineering, 2014, Vol. 56, nr 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    The thick N-B co-doped epilayers were grown by the fast sublimation growth method and the depth-resolved carrier lifetimes have been investigated by means of the free-carrier absorption (FCA) decay under perpendicular probe-pump measurement geometry. In some samples, we optically reveal in-grown carbon inclusions and polycrystalline defects of substantial concentration and show that these defects slow down excess carrier lifetime and prevent donor-acceptor pair photo luminescence (DAP PL). A pronounced electron lifetime reduction when injection level approaches the doping level was observed. It is caused by diffusion driven non-radiative recombination. However, the influence of surface recombination is small and insignificant at 300 K.

  • 171.
    Gudmundsson, Valur
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fabrication, characterization, and modeling of metallic source/drain MOSFETs2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    As scaling of CMOS technology continues, the control of parasitic source/drain (S/D) resistance (RSD) is becoming increasingly challenging. In order to control RSD, metallic source/drain MOSFETs have attracted significant attention, due to their low resistivity, abrupt junction and low temperature processing (≤700 °C). A key issue is reducing the contact resistance between metal and channel, since small Schottky barrier height (SBH) is needed to outperform doped S/D devices. A promising method to decrease the effective barrier height is dopant segregation (DS). In this work several relevant aspects of Schottky barrier (SB) contacts are investigated, both by simulation and experiment, with the goal of improving performance and understanding of SB-MOSFET technology:First, measurements of low contact resistivity are challenging, since systematic error correction is needed for extraction. In this thesis, a method is presented to determine the accuracy of extracted contact resistivity due to propagation of random measurement error.Second, using Schottky diodes, the effect of dopant segregation of beryllium (Be), bismuth (Bi), and tellurium (Te) on the SBH of NiSi is demonstrated. Further study of Be is used to analyze the mechanism of Schottky barrier lowering.Third, in order to fabricate short gate length MOSFETs, the sidewall transfer lithography process was optimized for achieving low sidewall roughness lines down to 15 nm. Ultra-thin-body (UTB) and tri-gate SB-MOSFET using PtSi S/D and As DS were demonstrated. A simulation study was conducted showing DS can be modeled by a combination of barrier lowering and doped Si extension.Finally, a new Schottky contact model was implemented in a multi-subband Monte Carlo simulator for the first time, and was used to compare doped-S/D to SB-S/D for a 17 nm gate length double gate MOSFET. The results show that a barrier of ≤ 0.15 eV is needed to comply with the specifications given by the International Technology Roadmap for Semiconductors (ITRS).

  • 172.
    Gudmundsson, Valur
    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.
    Luo, Jun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Lu, Jun
    Zhang, Shi-Li
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Fully Depleted UTB and Trigate N-Channel MOSFETs Featuring Low-Temperature PtSi Schottky-Barrier Contacts With Dopant Segregation2009Ingår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 30, nr 5, s. 541-543Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Schottky-barrier source/drain (SB-S/D) presents a promising solution to reducing parasitic resistance for device architectures such as fully depleted UTB, trigate, or FinFET. In this letter, a low-temperature process (<= 700 degrees C) with PtSi-based S/D is examined for the fabrication of n-type UTB and trigate FETs on SOI substrate (t(si) = 30 nm). Dopant segregation with As was used to achieve the n-type behavior at implantation doses of 1 (.) 10(15) and 5. 10(15) cm(-2). Similar results were found for UTB devices with both doses, but trigate devices with the larger dose exhibited higher on currents and smaller process variation than their lower dose counterparts.

  • 173.
    Gudmundsson, Valur
    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.
    Zhang, Shi-Li
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Characterization of dopant segregated Schottky barrier source/drain contacts2009Ingår i: ULIS 2009: 10TH INTERNATIONAL CONFERENCE ON ULTIMATE INTEGRATION OF SILICON / [ed] Mantl S, Lemme M, Schubert J, Albrecht W, NEW YORK: IEEE , 2009, s. 73-76Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper, the gate-voltage dependent source/drain (S/D) resistance (R-SD) in dopant segregated (DS) Schottky barrier (SB) junctions is examined by experiment and simulation. The focus is placed on fully depleted UTB-SOI MOSFETs featuring PtSi S/D with As-DS realized at low temperatures. When modeling SB-S/D with DS, it is challenging to determine if the performance enhancement observed is induced by a highly doped shallow layer in Si or by an interfacial dipole causing SB height lowering. The simulation reveals that the gate-voltage dependence of R-SD is stronger for the dipole effect. For the SB-MOSFETs with DS-S/D examined in this work, the simulation gives an excellent fit to the measured data when SBH lowering is combined with high concentration shallow doping.

  • 174.
    Gudmundsson, Valur
    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.
    Zhang, Shi-Li
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och tillämpad fysik, MAP.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Direct measurement of sidewall roughness on Si, poly-Si and poly-SiGe by AFM2008Ingår i: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY / [ed] Johansson LSO, Andersen JN, Gothelid M, Helmersson U, Montelius L, Rubel M, Setina J, Wernersson LE, Bristol: IOP PUBLISHING LTD , 2008, Vol. 100Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper the effect of the commonly used HBr/Cl-2 chemistry for dry etching on the line-edge roughness (LER) of photoresist patterned single crystalline Si (sc-Si), polycrystalline Si (poly-Si) and poly-Si0.2Ge0.8 sidewalls was characterized. Measurements were done by means of atomic force microscopy in combination with an elaborated sample preparation technique that allowed the LER at different depths of the sidewall to be measured. Samples were patterned by I-line lithography and etching was performed at an RF power of 200 W using HBr/Cl-2 (30/10 sccm) plasma. For sc-Si the photoresist and Si sidewalls had an LER of 0.8-1.4 nm and 1.5-2 nm, respectively. For poly-Si and poly-SiGe the photoresist sidewall roughness was, respectively, increased to 1.5-3 nm and 2-3.5 nm due to light scattering from the rough surface of the polycrystalline materials. The poly-Si film had a sidewall roughness of 3-4 nm. Poly-SiGe sidewall exhibited larger roughness with an LER of 5-12 nm which was not transferred from the photoresist. The results show that for sc-Si and poly-Si the sidewall roughness mainly originates from the photoresist process and little additional roughening is caused by the HBr/Cl-2 etching. However, for poly-Si0.2Ge0.8 the LER is considerably increased from that of the photoresist indicating that the HBr/Cl-2 etching is the main contributor to the LER.

  • 175.
    Gudmundsson, Valur
    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.
    Effect of Be segregation on NiSi/Si Schottky barrier heights2011Ingår i: Solid-State Device Research Conference (ESSDERC), 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    The effect of Be segregation on the Schottky barrier heights (SBH) of NiSi/Si is studied. Many elements have been shown to modulate the SBH of NiSi. However, group II elements have, to our knowledge, not been investigated before. Be is a double acceptor in Si, making it interesting for SBH modulation towards the valence band. The results show that Be implantation did not change the silicidation process. The SBH modulation was found to be strongly dependent on the silicidation temperature, with a minimum barrier to the valence band Φbp=0.28±0.02 eV, for diodes formed at 600 °C. SIMS analysis show the Be dose left at the interface is very low. With such a low dose, modulation cannot be caused by an interface dipole. However, the results can be explained assuming a thin (~4-5 nm) layer of activated Be close to the interface.

  • 176.
    Gudmundsson, Valur
    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.
    Error Propagation in Contact Resistivity Extraction Using Cross-Bridge Kelvin Resistors2012Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 59, nr 6, s. 1585-1591Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The cross-bridge Kelvin resistor is a commonly used method for measuring contact resistivity (rho(c)). For low rho(c), the measurement has to be corrected for systematic error using measurements of contact resistance, semiconductor sheet resistance, and device dimensions. However, it is not straightforward to estimate the propagation of random measurement error in the measured quantities on the extracted rho(c). In this paper, a method is presented to quantify the effect of random measurement error on the accuracy of rho(c) extraction. This is accomplished by generalized error propagation curves that show the error in rho(c) caused by random measurement errors. Analysis shows that when the intrinsic resistance of the contact is smaller than the semiconductor sheet resistance, it becomes important to consider random error propagation. Comparison of literature data, where rho(c) < 5.10(-8) Omega.cm(2) has been reported, shows that care should be taken since, even assuming precise electrical data, a 1% error in the measurement of device dimensions can lead to up to similar to 50% error in the estimation of rho(c).

  • 177.
    Gudmundsson, Valur
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Palestri, P.
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Selmi, L.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Simulation of low Schottky barrier MOSFETs using an improved Multi-subband Monte Carlo model2013Ingår i: Solid-State Electronics, ISSN 0038-1101, E-ISSN 1879-2405, Vol. 79, s. 172-178Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a simple and efficient approach to implement Schottky barrier contacts in a Multi-subband Monte Carlo simulator by using the subband smoothening technique to mimic tunneling at the Schottky junction. In the absence of scattering, simulation results for Schottky barrier MOSFETs are in agreement with ballistic Non-Equilibrium Green's Functions calculations. We then include the most relevant scattering mechanisms, and apply the model to the study of double gate Schottky barrier MOSFETs representative of the ITRS 2015 high performance device. Results show that a Schottky barrier height of less than approximately 0.15 eV is required to outperform the doped source/drain structure.

  • 178.
    Gudmundsson, Valur
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Palestri, Pierpaolo
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Selmi, Luca
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Investigation of the performance of low Schottky barrier MOSFETs using an improved Multi-subband Monte Carlo modelArtikel i tidskrift (Övrigt vetenskapligt)
  • 179.
    Gudmundsson, Valur
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Palestri, Pierpaolo
    Hellström, Per-Erik
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Selmi, Luca
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Multi-subband Monte Carlo simulation of fully-depleted silicon-on-insulator Schottky barrier MOSFETs2010Ingår i: 11th International Conference on Ultimate Integration of Silicon (ULIS), 2010, 2010Konferensbidrag (Refereegranskat)
  • 180. Gulbinas, K.
    et al.
    Ščajev, P.
    Bikbajavas, V.
    Grivickas, V.
    Korolik, O. V.
    Mazanik, A. V.
    Fedotov, A. K.
    Jokubaviius, V.
    Linnarsson, Margareta K.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Syväjärvi, M.
    Kamiyama, S.
    Raman scattering and carrier diffusion study in heavily Co-doped 6H-SiC layers2014Ingår i: IOP Conference Series: Materials Science and Engineering, 2014, Vol. 56, nr 1Konferensbidrag (Refereegranskat)
    Abstract [en]

    Thick 6H-SiC epilayers were grown using the fast sublimation method on low-off-axis substrates. They were co-doped with N and B impurities of ≈1019 cm-3 and (4·1016- 5·1018) cm-3 concentration, respectively. The epilayers exhibited donor-acceptor pair (DAP) photoluminescence. The micro-Raman spectroscopic study exposed a compensated n-6H-SiC epilayer of common quality with some 3C-SiC inclusions. The compensation ratio of B through 200 μm thick epilayer varied in 20-30% range. The free carrier diffusivity was studied by transient grating technique at high injection level. The determined ambipolar diffusion coefficient at RT was found to decrease from 1.15 cm2/s to virtually 0 cm2/s with boron concentration increasing by two orders.

  • 181. Gulbinas, Karolis
    et al.
    Grivickas, Vytautas
    Mahabadi, Haniyeh P.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Usman, Muhammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Surface Recombination Investigation in Thin 4H-SiC Layers2011Ingår i: Materials Science-Medziagotyra, ISSN 1392-1320, Vol. 17, nr 2, s. 119-124Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    n- and p-type 4H-SiC epilayers were grown on heavily doped SiC substrates. The thickness of the p-type layer was 7 mu m and the doping level around 10(17) cm(-3), while the n-type epilayers were 15 mu m thick and had a doping concentration of 3-5x10(15) cm(-3). Several different surface treatments were then applied on the epilayers for surface passivation: SiO(2) growth, Al(2)O(3) deposited by atomic layer deposition, and Ar-ion implantation. Using collinear pump - probe technique the effective carrier lifetimes were measured from various places and statistical lifetime distributions were obtained. For surface recombination evaluation, two models are presented. One states that surface recombination velocity (SRV) is equal on both the passivation/epi layer interface (S(2)) and the deeper interface between the epilayer and the SiC substrate (S(1)), i.e. (S(1) = S(2)). The other model is simulated assuming that SRV in the epilayer/substrate (S(1)) interface is constant while in the passivation layer/epilayer (S(2)) interface SRV can be varied S(2) < S(1). Empirical nomograms are presented with various parameters sets to evaluate S(2) values. We found that on the investigated 4H-SiC surfaces S(2) ranges from 3x10(4) to 5 x 10(4) assuming that the bulk lifetime is 4 mu s. In Ar(+) implanted surfaces S(2) is between (10(5)-10(6)) cm/s.

  • 182.
    Gustafsson, Oscar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Type-II interband quantum dot photodetectors2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Photon detectors based on single-crystalline materials are of great interest for high performance imaging applications due to their low noise and fast response. The major detector materials for sensing in the long-wavelength infrared (LWIR) band (8-14 µm) are currently HgCdTe (MCT) and AlGaAs/GaAs quantum wells (QW) used in intraband-based quantum-well infrared photodetectors (QWIPs). These either suffer from compositional variations that are detrimental to the system performance as in the case of MCT, or, have an efficient dark current generation mechanism that limits the operating temperature as for QWIPs. The need for increased on-wafer uniformity and elevated operating temperatures has resulted in the development of various alternative approaches, such as type-II strained-layer superlattice detectors (SLSs) and intraband quantum-dot infrared photodetectors (QDIPs).

    In this work, we mainly explore two self-assembled quantum-dot (QD) materials for use as the absorber material in photon detectors for the LWIR, with the aim to develop low-dark current devices that can allow for high operating temperatures and high manufacturability. The detection mechanism is here based on type-II interband transitions from bound hole states in the QDs to continuum states in the matrix material.

    Metal-organic vapor-phase epitaxy (MOVPE) was used to fabricate (Al)GaAs(Sb)/InAs and In(Ga)Sb/InAs QD structures for the development of an LWIR active material. A successive analysis of (Al)GaAs(Sb) QDs using absorption spectroscopy shows strong absorption in the range 6-12 µm interpreted to originate in intra-valence band transitions. Moreover, record-long photoluminescence (PL) wavelength up to 12 µm is demonstrated in InSb- and InGaSb QDs.

    Mesa-etched single-pixel photodiodes were fabricated in which photoresponse is demonstrated up to 8 µm at 230 K with 10 In0.5Ga0.5Sb QD layers as the active region. The photoresponse is observed to be strongly temperature-dependent which is explained by hole trapping in the QDs. In the current design, the photoresponse is thermally limited at typical LWIR sensor operating temperatures (60-120 K), which is detrimental to the imaging performance. This can potentially be resolved by selecting a matrix material with a smaller barrier for thermionic emission of photo-excited holes. If such an arrangement can be achieved, type-II interband InGaSb QD structures can turn out to be interesting as a high-operating-temperature sensor material for thermal imaging applications.

  • 183.
    Gustafsson, Oscar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ekenberg, Ulf
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik (Stängd 20120101), Fotonik (Stängd 20120101).
    Hallén, Anders
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Höglund, L.
    Karim, A.
    Noharet, B.
    Wang, Q.
    Gromov, A.
    Almqvist, S.
    Zhang, A.
    Acreo, Sweden.
    Junique, S.
    Andersson, J. Y.
    Asplund, C.
    von Würtemberg, R. Marcks
    Malm, H.
    Martijn, H.
    Long-wavelength infrared quantum-dot based interband photodetectors2011Ingår i: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 54, nr 3, s. 287-291Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits including long carrier lifetime due to the type-II band alignment, suppressed Shockley-Read-Hall generation-recombination due to the relatively large-bandgap matrix material, inhibited Auger recombination processes due to the tensile strain and epitaxial simplicity. Metal-organic vapor-phase epitaxy was used to grow multiple (Al)GaAs(Sb) QD layers on InAs substrates at different QD nominal thicknesses, compositions, doping conditions and multilayer periods, and the material was characterized using atomic force and transmission electron microscopy, and Fourier-transform infrared absorption spectroscopy. Dot densities up to 1 x 10(11) cm(-2), 1 x 10(12) cm(-2) and 3 x 10(10) cm(-2) were measured for GaAs, AlGaAs and GaAsSb QDs, respectively. Strong absorption in GaAs, AlGaAs and GaAsSb multilayer QD samples was observed in the wavelength range 6-12 mu m. From the wavelength shift in the spectral absorption for samples with varying QD thickness and composition it is believed that the absorption is due to an intra- valance band transition. From this it is possible to estimate the type-II inter-band transition wavelength, thereby suggesting that (Al)GaAs(Sb) QD/InAs heterostructures are suitable candidates for LWIR detection and imaging.

  • 184.
    Gustafsson, Oscar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Karim, Amir
    Asplund, Carl
    Wang, Qin
    Zabel, Thomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Almqvist, S.
    Savage, S.
    Andersson, Jan Y.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    A performance assessment of type-II interband In0.5Ga0.5Sb QD photodetectors2013Ingår i: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 61, s. 319-324Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Self-assembled quantum-dot (QD) structures with type-II band alignment to the surrounding matrix material have been proposed as a III/V material approach to realize small-bandgap device structures suitable for photon detection and imaging in the long-wavelength infrared (LWIR) band. Here, we analyze the photoresponse of In0.5Ga0.5Sb/InAs QD photodiodes and estimate the system performance of type-II QD - based photodetectors. A review of alternative design approaches is presented and the choice of matrix material is discussed in terms of band alignment and its effect on the photoresponse. Photodiodes were fabricated consisting of 10 layers of In0.5Ga0.5Sb QDs grown on InAs (0 0 1) substrates with metal-organic vapor-phase epitaxy (MOVPE). The photoresponse and dark current were measured in single pixel devices as a function of temperature in the range 20-230 K. The quantum efficiency shows an Arrhenius type behavior, which is attributed to hole trapping. This severely limits the detector performance at typical LWIR sensor operating temperatures (60-120 K). A device design with the matrix material InAs0 6Sb0 4 is proposed as a mean to improve the performance by reducing the barrier for hole transport. This can potentially allow type-II InGaSb QDs to be a competitive sensor material for LWIR detection.

  • 185.
    Gustafsson, Oscar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Karim, Amir
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Wang, Qin
    Reuterskiöld-Hedlund, Carl
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ernerheim-Jokumsen, Christopher
    KTH.
    Soldemo, Markus
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Weissenrieder, Jonas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Persson, Sirpa
    Almqvist, Susanne
    Ekenberg, Ulf
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Fotonik och optik.
    Noharet, Bertrand
    Asplund, Carl
    Göthelid, Mats
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Materialfysik, MF.
    Andersson, Jan Y.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Photoluminescence and photoresponse from InSb/InAs-based quantum dot structures2012Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, nr 19, s. 21264-21271Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    InSb-based quantum dots grown by metal-organic vapor-phase epitaxy (MOVPE) on InAs substrates are studied for use as the active material in interband photon detectors. Long-wavelength infrared (LWIR) photoluminescence is demonstrated with peak emission at 8.5 mu m and photoresponse, interpreted to originate from type-II interband transitions in a p-i-n photodiode, was measured up to 6 mu m, both at 80 K. The possibilities and benefits of operation in the LWIR range (8-12 mu m) are discussed and the results suggest that InSb-based quantum dot structures can be suitable candidates for photon detection in the LWIR regime.

  • 186.
    Gustafsson, Oscar
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Karim, Amir
    Wang, Qin
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Asplund, Carl
    Andersson, Jan Y.
    Hammar, Mattias
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Long-wavelength infrared photoluminescence from InGaSb/InAs quantum dots2013Ingår i: Infrared physics & technology, ISSN 1350-4495, E-ISSN 1879-0275, Vol. 59, s. 89-92Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the growth of self-assembled InGaSb/InAs quantum dots (QDs) and investigate how gallium can be used to reduce the optical transition energy in the InSb QD system. InGaSb QDs were grown on InAs (0 0 1) substrates by metal-organic vapor-phase epitaxy (MOVPE) and the material was characterized by photoluminescence (PL) measurements. A PL peak wavelength is demonstrated beyond 8 μm at 77 K, which is significantly longer than what has been reported for InSb QDs. The results suggest that InGaSb QDs can be grown at a larger size than InSb QDs leading to reduced confinement in the QDs.

  • 187.
    Gylfason, Kristinn B.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Fischer, Andreas C.
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Gunnar Malm, B. Gunnar
    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.
    Belova, Lyubov M.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Niklaus, Frank
    KTH, Skolan för elektro- och systemteknik (EES), Mikrosystemteknik (Bytt namn 20121201).
    Process considerations for layer-by-layer 3D patterning of silicon, using ion implantation, silicon deposition, and selective silicon etching2012Ingår i: Journal of Vacuum Science & Technology B, ISSN 1071-1023, E-ISSN 1520-8567, Vol. 30, nr 6, s. 06FF05-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors study suitable process parameters, and the resulting pattern formation, in additive layer-by-layer fabrication of arbitrarily shaped three-dimensional (3D) silicon (Si) micro- and nanostructures. The layer-by-layer fabrication process investigated is based on alternating steps of chemical vapor deposition of Si and local implantation of gallium ions by focused ion beam writing. In a final step, the defined 3D structures are formed by etching the Si in potassium hydroxide, where the ion implantation provides the etching selectivity.

  • 188. Haidar, M.
    et al.
    Durrenfeld, P.
    Ranjbar, M.
    Balinsky, M.
    Fazlali, M.
    Dvornik, M.
    Dumas, R. K.
    Khartsev, Sergiy
    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. University of Gothenburg, Sweden.
    Controlling Gilbert damping in a YIG film using nonlocal spin currents2016Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 94, nr 18, artikel-id 180409Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate the control of Gilbert damping in 65-nm-thick yttrium iron garnet (YIG) films using a spin-polarized current generated by a direct current through a nanocontact, spin filtered by a thin Co layer. The magnetodynamics of both the YIG and the Co layers can be excited by a pulse-modulated microwave current injected through the nanocontact and the response detected as a lock-in amplified voltage over the device. The spectra show three clear peaks, two associated with the ferromagnetic resonance (FMR) in each layer, and an additional Co mode with a higher wave vector proportional to the inverse of the nanocontact diameter. By varying the sign and magnitude of the direct nanocontact current, we can either increase or decrease the linewidth of the YIG FMR peak consistent with additional positive or negative damping being exerted by the nonlocal spin current injected into the YIG film. Our nanocontact approach thus offers an alternative route in the search for auto-oscillations in YIG films.

  • 189. Haidar, M.
    et al.
    Ranjbar, M.
    Balinsky, M.
    Dumas, R. K.
    Khartsev, Sergiy
    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. University of Gothenburg, Sweden.
    Thickness- and temperature-dependent magnetodynamic properties of yttrium iron garnet thin films2015Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 117, nr 17, artikel-id 17D119Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The magnetodynamical properties of nanometer-thick yttrium iron garnet films are studied using ferromagnetic resonance as a function of temperature. The films were grown on gadolinium gallium garnet substrates by pulsed laser deposition. First, we found that the damping coefficient increases as the temperature increases for different film thicknesses. Second, we found two different dependencies of the damping on film thickness: at room temperature, the damping coefficient increases as the film thickness decreases, while at T = 8 K, we find the damping to depend only weakly on the thickness. We attribute this behavior to an enhancement of the relaxation of the magnetization by impurities or defects at the surfaces.

  • 190.
    Hallén, Anders
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Linnarsson, Margareta K.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ion implantation technology for silicon carbide2016Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 306, s. 190-193Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ion implantation is a key process technique for semiconductor materials, in particular silicon, for local tailoring of the semiconductor properties. The wide bandgap semiconductor silicon carbide (SiC) features outstanding material properties for high power and high temperature electronic devices, but the properties of SiC also make it difficult to manufacture and process the material. The development of implantation technology for SiC has therefore necessitated several changes, from mainstream silicon implantation technology. This paper will discuss the difficulties with implantation of SiC for manufacturing of electronic devices and also describe how the problems have been overcome, for instance by implantation at elevated temperatures and using high temperature post-implant annealing. (C) 2016 Elsevier B.V. All rights reserved.

  • 191.
    Hallén, Anders
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Moschetti, Giuseppe
    RBS channeling measurement of damage annealing in InAs/AlSb HEMT structures2014Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 332, s. 172-175Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electrical isolation of InAs/AlSb high electron mobility transistors has been achieved by the ion implantation isolation technique. The multilayered structures are grown by molecular beam epitaxy on GaAs substrates. The optimal isolation is provided by damaging patterned areas by 100 keV Ar ions implanted at room temperature using fluence of 2 x 10(15) cm(-2), and then annealing the samples in 365 degrees C for 30 min. The damage build-up and annealing is studied by channeling Rutherford backscattering spectrometry (RBS) and compared to sheet resistance measurements. Only a low level of damage annealing can be seen in RBS for the post-implant annealed samples, but for Ar fluence higher than 2 x 10(14) cm(-2), a strong electrical resistivity increase can still be achieved.

  • 192.
    Hallén, Anders
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Usman, M.
    Suvanam, Sethu Saveda
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Henkel, Christoph
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Martin, David M.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Linnarsson, Margareta K.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Passivation of SiC device surfaces by aluminum oxide2014Ingår i: IOP Conference Series: Materials Science and Engineering, ISSN 1757-8981, E-ISSN 1757-899X, Vol. 56, nr 1, s. 012007-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A steady improvement in material quality and process technology has made electronic silicon carbide devices commercially available. Both rectifying and switched devices can today be purchased from several vendors. This successful SiC development over the last 25 years can also be utilized for other types of devices, such as light emitting and photovoltaic devices, however, there are still critical problems related to material properties and reliability that need to be addressed. This contribution will focus on surface passivation of SiC devices. This issue is of utmost importance for further development of SiC MOSFETs, which so far has been limited by reliability and low charge carrier surface mobilities. Also bipolar devices, such as BJTs, LEDs, or PV devices will benefit from more efficient and reliable surface passivation techniques in order to maintain long charge carrier lifetimes. Silicon carbide material enables the devices to operate at higher electric fields, higher temperatures and in more radiation dense applications than silicon devices. To be able to utilize the full potential of the SiC material, it is therefore necessary to develop passivation layers that can sustain these more demanding operation conditions. In this presentation it will also be shown that passivation layers of Al2O3 deposited by atomic layer deposition have shown superior radiation hardness properties compared to traditional SiO2-based passivation layers.

  • 193.
    Hamawandi, Bejan
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Noroozi, Mohammad
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Jayakumar, Ganesh
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Ergül, Adem
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Zahmatkesh, Katayoun
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Toprak, Muhammet S.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Material- och nanofysik, Funktionella material, FNM.
    Radamson, Henry H.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Electrical properties of sub-100 nm SiGe nanowires2016Ingår i: Journal of semiconductors, Vol. 37, nr 10Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the electrical properties of SiGe nanowires in terms of process and fabrication integrity, measurement reliability, width scaling, and doping levels were investigated. Nanowires were fabricated on SiGe-on oxide (SGOI) wafers with thickness of 52 nm and Ge content of 47%. The first group of SiGe wires was initially formed by using conventional I-line lithography and then their size was longitudinally reduced by cutting with a focused ion beam (FIB) to any desired nanometer range down to 60 nm. The other nanowires group was manufactured directly to a chosen nanometer level by using sidewall transfer lithography (STL). It has been shown that the FIB fabrication process allows manipulation of the line width and doping level of nanowires using Ga atoms. The resistance of wires thinned by FIB was 10 times lower than STL wires which shows the possible dependency of electrical behavior on fabrication method.

  • 194.
    Hammar, Mattias
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Xiang, Yu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Yu, Xingang
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Berggren, Jesper
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Zabel, Thomas
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Akram, M. N.
    Room-temperature operation of 980-nm transistor-vertical-cavity surface-emitting lasers2013Ingår i: 2013 IEEE 6th International Conference on Advanced Infocomm Technology, ICAIT 2013, IEEE , 2013, s. 141-142Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report on the design, fabrication and characterization of pnp-type 980-nm transistor-vertical-cavity surface-emitting lasers (T-VCSELs). Using an epitaxial regrowth process and a triple-intracavity current injection scheme we demonstrate static performance levels quite comparable to those of conventional VCSELs, including sub-mA threshold base current, mW-range output power and continuous-wave operation at least up to 50°C.

  • 195.
    Haralson, Erik
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Suvar, E.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Malm, B. Gunnar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Radamson, Henry
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Wang, Yong-Bin
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Östling, Mikael
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    NiSi integration in a non-selective base SiGeCHBT process2005Ingår i: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 8, nr 03-jan, s. 245-248Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A self-aligned nickel silicide (salicide) process is integrated into a non-selective base SiGeC HBT process. The device features a unique, fully silicided base region that grows laterally under the emitter pedestal. This Ni(SiGe) formed in this base region was found to have a resistivity of 23-24 muOmega cm. A difference in the silicide thickness between the boron-doped SiGeC extrinsic base region and the in situ phosphorous-doped emitter region is observed and further analyzed and confirmed with a blanket wafer silicide study. The silicided device exhibited a current gain of 64 and HF device performance of 39 and 32 GHz for f(t) and f(MAX), respectively.

  • 196.
    Hedayati, Raheleh
    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.
    Malm, Bengt Gunnar
    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 500 degrees C 8-b Digital-to-Analog Converter in Silicon Carbide Bipolar Technology2016Ingår i: IEEE Transactions on Electron Devices, ISSN 0018-9383, E-ISSN 1557-9646, Vol. 63, nr 9, s. 3445-3450Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-temperature integrated circuits provide important sensing and controlling functionality in extreme environments. Silicon carbide bipolar technology can operate beyond 500 degrees C and has shown stable operation in both digital and analog circuit applications. This paper demonstrates an 8-b digital-to-analog converter (DAC). The DAC is realized in a current steering R-2R configuration. High-gain Darlington current switches are used to ensure ideal switching at 500 degrees C. The measured differential nonlinearity (DNL) and integral nonlinearity (INL) at 25 degrees C are 0.79 and 1.01 LSB, respectively, while at 500 degrees C, the DNL and INL are 4.7 and 2.5 LSB, respectively. In addition, the DAC achieves 53.6 and 40.6 dBc of spurious free dynamic range at 25 degrees C and 500 degrees C, respectively.

  • 197.
    Hedayati, Raheleh
    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.
    Rodriguez, Saul
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Malm, Bengt Gunnar
    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, 500 degrees C Operational Amplifier in 4H-SiC Bipolar Technology2014Ingår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 35, nr 7, s. 693-695Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A monolithic bipolar operational amplifier (opamp) fabricated in 4H-SiC technology is presented. The opamp has been used in an inverting negative feedback amplifier configuration. Wide temperature operation of the amplifier is demonstrated from 25 degrees C to 500 degrees C. The measured closed loop gain is around 40 dB for all temperatures whereas the 3 dB bandwidth increases from 270 kHz at 25 degrees C to 410 kHz at 500 degrees C. The opamp achieves 1.46 V/mu s slew rate and 0.25% total harmonic distortion. This is the first report on high temperature operation of a fully integrated SiC bipolar opamp which demonstrates the feasibility of this technology for high temperature analog integrated circuits.

  • 198.
    Hedayati, Raheleh
    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.
    Wide Temperature Range Integrated Amplifier in Bipolar 4H-SiC Technology2016Ingår i: 2016 46TH EUROPEAN SOLID-STATE DEVICE RESEARCH CONFERENCE (ESSDERC), IEEE, 2016, s. 198-201Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents a high temperature integrated amplifier implemented in bipolar 4H-SiC technology. A 40 dB negative feedback voltage amplifier has been designed using the structured design method to overcome the temperature variation of device parameters. The amplifier performance degrades as the temperature increases from room temperature up to 500 degrees C. The measured gain is reduced from 39 dB at room temperature to 34 dB at 500 degrees C, and the 3-dB bandwidth decreases from 195 kHz to 100 kHz. The measured power-supply-rejection-ratio (PSRR) is reduced from -78 dB to -62 dB, while the output voltage swing decreases from 8 V to 7 V.

  • 199.
    Hedayati, Raheleh
    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.
    Wide Temperature Range Integrated Bandgap Voltage References in 4H–SiC2016Ingår i: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 37, nr 2, s. 146-149Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Three fully integrated bandgap voltage references (BGVRs) have been demonstrated in a 4H-SiC bipolar technology. The circuits have been characterized over a wide temperature range from 25 degrees C to 500 degrees C. The three BGVRs are functional and exhibit 46 ppm/degrees C, 131 ppm/degrees C, and 120 ppm/degrees C output voltage variations from 25 degrees C up to 500 degrees C. This letter shows that SiC bipolar BGVRs are capable of providing stable voltage references over a wide temperature range.

  • 200.
    Hedayati, Raheleh
    et al.
    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.
    Material aspects of wide temperature range amplifier design in SiC bipolar technologies2016Ingår i: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 31, nr 19, s. 2928-2935Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Silicon carbide (SiC) is the main semiconductor alternative for low loss high voltage devices. The wide energy band gap also makes it suitable for extreme environment electronics, including very high temperatures. Operating integrated electronics at 500-600 °C poses several materials challenges. However, once electronics is available for these high temperatures, the added challenge is designing integrated circuits capable of operating in the entire range from room temperature to 500 °C. Circuit designers have to take into account parameter variations of resistors and transistors, and models are needed for several temperatures. A common circuit design technique to manage parameter variations between different transistors, without wide temperature variations, is to use negative feedback in amplifier circuits. In this paper we show that this design technique is also useful for adapting to temperature changes during operation. Two different amplifier designs in SiC are measured and simulated from room temperature up to 500 °C.

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