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  • 1.
    Ackelid, Ulf
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Armgarth, M.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ethanol sensitivity of palladium-gate metal-oxide-semiconductor structures1986In: IEEE Electron Device Letters, ISSN 0741-3106, E-ISSN 1558-0563, Vol. 7, no 6, p. 353-355Article in journal (Refereed)
    Abstract [en]

    Hydrogen-sensitive palladium-gate MOS structures heated above 150°C show sensitivity to ethanol vapor. The effect is probably due to catalytic dehydrogenation of adsorbed ethanol molecules on the surface of the palladium gate.

  • 2.
    Afzal, Adeel
    et al.
    University of Bari Aldo Moro, Italy; King Fahd University of Petr and Minerals, Saudi Arabia; University of Hafr Al Batin, Saudi Arabia.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Di Franco, Cinzia
    CNR IFN UOS Bari, Italy.
    Ditaranto, Nicoletta
    University of Bari Aldo Moro, Italy.
    Cioffi, Nicola
    University of Bari Aldo Moro, Italy; University of Bari Aldo Moro, Italy.
    Scamarcio, Gaetano
    CNR IFN UOS Bari, Italy; University of Bari Aldo Moro, Italy.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Torsi, Luisa
    University of Bari Aldo Moro, Italy; University of Bari Aldo Moro, Italy.
    Electrochemical deposition of gold on indium zirconate (InZrOx with In/Zr atomic ratio 1.0) for high temperature automobile exhaust gas sensors2015In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 19, no 9, p. 2859-2868Article in journal (Refereed)
    Abstract [en]

    Automobile exhaust gas emissions are causing serious damage to urban air quality in and around major cities of the world, which demands continuous monitoring of exhaust emissions. The chief components of automobile exhaust include carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons. Indium zirconate (InZrOx) and gold/indium zirconate (Au/InZrOx) composite nanopowders are believed to be interesting materials to detect these substances. To this end, characterization and gas sensing properties of InZrOx and Au/InZrOx composite nanopowders are discussed. InZrOx nanoparticles with In/Zr atomic ratio of 1.00 (+/- 0.05) are synthesized via pH-controlled co-precipitation of In and Zr salts in aqueous ammonia. Gold (Au) nanoparticles are subsequently deposited on InZrOx using an in situ sacrificial Au electrolysis procedure. The products are characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing performance of Au/InZrOx composite nanopowder is studied by depositing a thick powder film on interdigitated electrode structures patterned on SiC substrate to facilitate high temperature operation. The resistivity of the Au/InZrOx layer is the sensor signal, and the sensors could be operated at 500-600 A degrees C, which is a suitable temperature range for engine exhaust measurements. The control sensing measurements reveal that Au/InZrOx composite nanopowder exhibits higher response towards 2-20 % O-2 gas as compared to pristine InZrOx nanoparticles. Further studies show that when applied to exhaust gases such as CO and nitric oxide (NO), the response of Au/InZrOx sensors is significantly higher towards NO in this temperature range. Thus, sensor performance characteristics of Au/InZrOx composite nanopowder are promising in terms of their applications in automobile exhaust emission control.

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  • 3.
    Alene Asres, Georgies
    et al.
    University of Oulu, Finland.
    Dombovari, Aron
    University of Oulu, Finland.
    Sipola, Teemu
    University of Oulu, Finland.
    Puskas, Robert
    University of Szeged, Hungary.
    Kukovecz, Akos
    University of Szeged, Hungary; MTA SZTE Lendulet Porous Nanocomposites Research Grp, Hungary.
    Konya, Zoltan
    University of Szeged, Hungary; MTA SZTE React Kinet and Surface Chemistry Research Grp, Hungary.
    Popov, Alexey
    University of Oulu, Finland.
    Lin, Jhih-Fong
    University of Oulu, Finland.
    Lorite, Gabriela S.
    University of Oulu, Finland.
    Mohl, Melinda
    University of Oulu, Finland.
    Toth, Geza
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Kordas, Krisztian
    University of Oulu, Finland.
    A novel WS2 nanowire-nanoflake hybrid material synthesized from WO3 nanowires in sulfur vapor2016In: Scientific Reports, E-ISSN 2045-2322, Vol. 6, no 25610Article in journal (Refereed)
    Abstract [en]

    In this work, WS2 nanowire-nanoflake hybrids are synthesized by the sulfurization of hydrothermally grown WO3 nanowires. The influence of temperature on the formation of products is optimized to grow WS2 nanowires covered with nanoflakes. Current-voltage and resistance-temperature measurements carried out on random networks of the nanostructures show nonlinear characteristics and negative temperature coefficient of resistance indicating that the hybrids are of semiconducting nature. Bottom gated field effect transistor structures based on random networks of the hybrids show only minor modulation of the channel conductance upon applied gate voltage, which indicates poor electrical transport between the nanowires in the random films. On the other hand, the photo response of channel current holds promise for cost-efficient solution process fabrication of photodetector devices working in the visible spectral range.

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  • 4.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Bastuk, Manuel
    Saarland University, Saarbruecken, Germany.
    Huotari, Joni
    University of Oulu, Finland.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Lappalainen, Jyrki
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Optimization of the Field Effect Transistor transducer platform for the development of air quality sensors2016In: Proceedings EMRS 2016, 2016Conference paper (Refereed)
  • 5.
    Andersson, Mike
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Becker, Elin
    Chalmers Tekniska Högskola.
    Lloyd Spetz, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Skoglund, Magnus
    Chalmers Tekniska Högskola.
    In situ DRIFT study of the CO response mechanism of MISFET sensors using Pt/SiO2 model sensor2008In: Proceedings of IEEE Sensors, IEEE , 2008, p. 1309-1312Conference paper (Refereed)
    Abstract [en]

    The temperature dependence of the sensor response towards CO of SiC-FET sensors has been studied by combining in situ DRIFT spectroscopy and sensor response measurements. The DRIFT spectroscopy studies have been performed on a model sensor representing the top layer of a SiC-FET sensor with porous Pt gate. Adsorbates on the model sensor have been studied at varying temperatures and gas concentrations, and correlated to sensor response measurements at similar experimental conditions. The results show that the temperature dependence partly can be correlated to the CO coverage of the surface. The switching point of the sensor response, observed at different temperatures depending on the CO and oxygen concentrations is well in accordance with the kinetics of the CO oxidation reaction.

  • 6.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Buchholt, Kristina
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Wingbrant, Helena
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    On the CO response mechanism of SiC based field effect gas sensorsManuscript (Other academic)
    Abstract [en]

    The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards carbon monoxide (CO) at varying oxygen (O2) concentrations and over a wide range of temperatures have been investigated in detail at atmospheric pressure. The influence of hydrogen (H2) on the CO response was also studied. Sensor devices with thin, porous as well as dense, homogeneous Pt films on top of both silicon dioxide (SiO2) and magnesium oxide (MgO) as insulator materials were investigated in this study. The reaction products generated on the sensor surfaces were also monitored with a mass spectrometer connected to the gas flow just downstream of the sensor location and the results compared to CO oxidation characteristics over Pt/SiO2 and to some extent Pt/MgO catalysts as reported in literature. By correlating the response characteristics of these devices with CO2 formation and hydrogen consumption on the sensor surfaces, strong indications for a CO response mechanism involving a CO induced increased sensitivity to background hydrogen have been obtained, this mechanism being hypothesized to be the only one behind the CO sensitivity of devices with dense Pt metal contacts. The results also give further support to the idea that also other processes than an increased sensitivity to background hydrogen contribute to the CO response of sensor devices with a porous platinum film as the metal contact, one candidate being the removal of oxygen anions from the surface of exposed oxide areas through the oxidation reaction with CO.

  • 7.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Buchholt, Kristina
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Wingbrant, Helena
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    On the response mechanism of SiC based field effect gas sensors towards non-hydrogen containing species and specifically NOManuscript (Other academic)
    Abstract [en]

    The response characteristics of Metal Insulator Silicon Carbide (MISiC) field effect sensor devices, with platinum (Pt) as the metal contact, towards nitrogen oxide (NO) for both low as well as relatively high background oxygen (O2) concentrations and different temperatures have been investigated at atmospheric pressure. Devices with both porous and dense Pt metal gate contacts have been investigated and the results seem to confirm the theories and results from earlier measurements regarding the requirement of porous metal films for the existence of a response to NO for this kind of sensor device. The results also suggest that no NO induced increased sensitivity to background hydrogen exists, at least it does not play any role in the observed NO sensitivity, as opposed to what has been suggested in the case of CO. The obtained results are also discussed in relation to some of the proposed sensing mechanisms for non-hydrogen containing substances and in comparison to NO reduction characteristics on Pt/SiO2 catalysts, as reported in literature. The results further give some indications about also some other process/ processes being important for the response of SiC based field effect sensors towards NO than just adsorption/desorption.

  • 8.
    Andersson, Mike
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Everbrand, Lars
    Lloyd Spetz, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Nyström, T
    NIBE.
    Nilsson, M
    NIBE.
    Gauffin, C
    Svensson, H
    A MISiCFET based gas sensor system for combustion control in small-scale wood fired boilers2007In: IEEE Sensors,2007, 2007, p. 962-Conference paper (Refereed)
  • 9.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Everbrand, Lars
    Nyström, Torkel
    Nilsson, Mikael
    Gauffin, Claes
    Svensson, Holger
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    A novel sensor system based on gas sensitive MISiCFET devices for combustion control in small-scale wood fired boilers2007Article in journal (Refereed)
  • 10.
    Andersson, Mike
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Holmberg, Martin
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Martensson, P.
    Paolesse, R.
    Department of Chemical Science and Technology, University of Rome (Tor Vergata), via della Ricerca Scientifica, 00133 Rome, Italy.
    Falconi, C.
    Department of Electronic Engineering, University of Rome (Tor Vergata), Via di Tor Vergata 110, 00133 Rome, Italy.
    Proietti, E.
    Department of Electronic Engineering, University of Rome (Tor Vergata), Via di Tor Vergata 110, 00133 Rome, Italy.
    Di, Natale C.
    Di Natale, C., Department of Electronic Engineering, University of Rome (Tor Vergata), Via di Tor Vergata 110, 00133 Rome, Italy.
    D'Amico, A.
    Department of Electronic Engineering, University of Rome (Tor Vergata), Via di Tor Vergata 110, 00133 Rome, Italy.
    Development of a ChemFET sensor with molecular films of porphyrins as sensitive layer2001In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 77, no 1-2, p. 567-571Article in journal (Refereed)
    Abstract [en]

    The interaction of chemical species with molecular films of porphyrins causes variations of the work function of the film itself, as it has been recently demonstrated by using the Kelvin probe technique. This characteristic makes porphyrins films suitable to be used as sensitive layers in ChemFET sensors. In this paper, we present a preliminary report about the fabrication and testing of such gas sensitive devices. The technological solutions towards an optimised device are also illustrated and discussed. © 2001 Elsevier Science B.V.

  • 11.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ljung, Per
    Vattenfall Utveckling AB, Älvkarleby, Sweden.
    Mattsson, Mattias
    Vattenfall Utveckling AB, Älvkarleby, Sweden.
    Löfdahl, Mikael
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Investigations on the possibilities of a MISiCFET sensor system for OBD and combustion control utilizing different catalytic gate materials2004In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 30-31, no 1, p. 365-368Article in journal (Refereed)
    Abstract [en]

    Different catalytic materials, like Pt and Ir, applied as gate contacts on metal insulator silicon carbide field effect transistors — MISiCFET—facilitate the manufacture of gas sensor devices with differences in selectivity, devices which due to the chemical stability and wide band gap of SiC are suitable for high temperature applications. The combination of such devices in a sensor system, utilizing multivariate analysis/modeling, have been tested and some promising results in respect of monitoring a few typical exhaust and flue gas constituents, in the future aiming at on board diagnostics (OBD) and combustion control, have been obtained.

  • 12.
    Andersson, Mike
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Lloyd Spetz, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics.
    Detecting non-hydrogen containing species with field effect devices2008In: IEEE Sensors,2008, IEEE , 2008, p. 1320-1323Conference paper (Refereed)
    Abstract [en]

    An investigation of the influence and role of oxygen in the detection of non-hydrogen containing substances with Pt/SiO2/SiC based MOS field effect sensors, employing new model systems, has been carried out. With the use of a novel intermediate layer, by which the direct influence of hydrogen on the sensor response can be markedly reduced, the part of the sensor response which is not directly related to hydrogen (which to a small extent is always present in any gas mixture) could be resolved. The Pt/SiO2 NO reduction/oxidation model system has also been studied from a sensor perspective and the results compared to spectroscopic and mass spectrometry studies of the surface reactions from the field of catalysis. The results support the hypothesis from earlier work that the removal of oxygen from the sensor surface (e.g. by oxidation reactions with CO or NO) to a certain extent directly is involved in the detection of non-hydrogen containing species.

  • 13.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Tailoring of field effect gas sensors for sensing of non-hydrogen containing substances from mechanistic studies on model systems2009Conference paper (Refereed)
    Abstract [en]

    To gain knowledge about the transduction mechanisms involved in the sensitivity of field effect gas sensors towards non-hydrogen containing substances, such as O-2, NO and CO, the sensor signal characteristics during exposure of some conceptually different model sensors to these as well as hydrogen containing gases have been investigated. The MOS capacitor based model sensors employ different combinations of insulator and contact materials, such as MgO, LaF3, IrO2 etc. The gas composition downstream of the sensor during test gas exposure at various conditions has also been studied by mass spectrometry (MS) and compared for the different model systems. The results have been compared to the characteristics of ordinary SiC/SiO2/Pt structures and from the information obtained a tailor made field effect sensor structure for oxygen sensing, to our knowledge for the first time with minimal interference from H-2, CO, and hydrocarbons, has been tested with promising results.

  • 14.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Tailoring of SiC based field effect gas sensors for improved selectivity t non-hydrogen containing species2010In: IMCS13 2010, 2010, p. 369-Conference paper (Refereed)
  • 15.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Technology and application opportunities for SiC-FET gas sensors2012In: Solid State Gas Sensors - Industrial Application / [ed] Maximilian Fleischer and Mirko Lehmann, Springer Berlin/Heidelberg, 2012, p. 189-214Chapter in book (Refereed)
    Abstract [en]

    The development of SiC-FET gas sensors has proceeded for about fifteen years. The maturity of the SiC material and a deeper understanding of the transduction mechanisms and sensor surface processes behind the sensitivity to a number of target substances have recently allowed the development of market-ready sensors for certain applications. Some examples presented below are a sensor system for domestic boiler control, an ammonia sensor for control of the SCR (selective catalytic reduction) and SNCR (Selective Non-Catalytic Reduction) NOx abatement processes as well as other more or less market-ready applications. In parallel, the basic research continues in order to reach more demanding markets/new applications and also to possibly lower the production costs of the sensors. Therefore, current research and future challenges are also treated, such as the development of new types of conducting ceramics for ohmic contacts to SiC in order to increase the operation temperature beyond the present state of the art.

  • 16.
    Andersson, Mike
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lloyd Spetz, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Becker, Elin
    Skoglundh, Magnus
    Chalmers Tekniska Högskola.
    In Situ DRIFT study of hydrogen and CO adsorption on Pt/SiO2 model sensors2007In: IEEE Sensors,2007, 2007, p. 1028-Conference paper (Refereed)
  • 17.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Mattsson, Mattias
    Vattenfall Utveckling AB, Älvkarleby, Sweden.
    Ljung, Per
    Vattenfall Utveckling AB, Älvkarleby, Sweden.
    On the applicability of MISiCFET gas sensors regarding ammonia slip monitoring in small-scale boilers running SNCR2007Manuscript (preprint) (Other academic)
    Abstract [en]

    Gas sensitive Metal Insulator Silicon Carbide Field Effect Transistor – MISiCFET – devices have shown good possibilities of realizing sensors for high temperature applications. One such application could be the monitoring of ammonia slip from boilers running SNCR – Selective Non-Catalytic Reduction of nitrogen oxides (NOx) with ammonia (NH3). In this study a number of MISiCFET gas sensors operated at different temperatures and with both platinum (Pt) and iridium (Ir) as the gate contact have been tested for their ability to detect and quantify ammonia slip in flue gases from a 5.6 MW wood fired boiler during a test of a new SNCR-system. The individual sensors have been evaluated and compared to each other for the sensitivity towards NH3 and possible cross-sensitivities to other flue gas species through the comparison of the sensor signals with the signals from analytical instruments like FTIR – Fourier Transform Infrared spectroscopy – for nitrogen oxides (NO + NO2), NH3, and carbon monoxide (CO) and an FID – Flame Ionization Detector – for the Total Hydrocarbon Concentration (THC). The ability of a combination of sensors to provide extra or more accurate information about the NH3 concentration was also evaluated through the construction and validation of a Partial Least Squares – PLS – regression model based on all the sensor signals. Under the assumption that the sensors’ responses follow a logarithmic dependence on NH3 concentration the results regarding  ammonia slip quantification were promising both for a single Ir sensor and for the system based on all sensors. There is still a question mark for the long-term stability of the devices in real flue gases, however.

  • 18.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Pearce, Ruth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. NPL, London from March 2012.
    Recent trends in Silicon Carbide (SiC) and Graphene based gas sensors2013In: Semiconductor Gas Sensors / [ed] R. Jaaniso and O. K. Tan, Woodhead Publishing Limited, 2013, p. 117-158Chapter in book (Refereed)
    Abstract [en]

    The introduction of silicon carbide (SiC) as the semiconductorin gas sensitive field effect devices has tremendously improved this sensor platform extending the temperature range and number of detectable gases. Here we review the recent trends in research, starting with transducer mechanisms, latest findings regarding the detection mechanism, and present new material combinations as sensing layers and smart operation of the field effect sensors enabling one sensor to act as a sensor array. Introducing epitaxially-grown graphene on SiC as gas sensing layer shows the potential of ppb detection of NO2 .

  • 19.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Pearce, Ruth
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Tunable gas alarms for high temperature applications based on 4H-SiC MISFET devices2011In: Proceedings of the International Conference on Silicon Carbide and Related materials, 2011, p. 365-Conference paper (Refereed)
  • 20.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Recent progress in silicon carbide field effect gas sensors2020In: Semiconductor gas sensors / [ed] Raivo Jaaniso and Ooi Kiang Tan, Oxford: Woodhead Publishing Limited, 2020, 2, p. 309-346Chapter in book (Refereed)
    Abstract [en]

    The introduction of silicon carbide as the semiconductor in gas-sensitive field effect devices has disruptively improved this sensor platform extending the operation temperature to more than 600 °C with an increased number of detectable gases. Here, we review recent progress in research and applications, starting with transducer and detection mechanisms, presenting new material combinations as sensing layers for improved selectivity and detection limits down to subparts per billion. We describe how temperature cycled operation combined with advanced data evaluation enables one sensor to act as a sensor array thereby vastly improving selectivity. Field tests require advanced packaging, which is described, and examples of possible applications like selective detection of ammonia for urea injection control in diesel exhausts and toxic volatile organic compounds for indoor air quality monitoring and control are given.

  • 21.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Fashandi, Hossein
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Huotari, J.
    University of Oulu, Finland.
    Puustinen, J.
    University of Oulu, Finland.
    Lappalainen, J.
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Field Effect Based Gas Sensors, from Basic Mechanisms to the Latest Commercial Device Designs2016In: SENSORS AND ELECTRONIC INSTRUMENTATION ADVANCES (SEIA), INT FREQUENCY SENSOR ASSOC-IFSA , 2016, p. 19-21Conference paper (Refereed)
    Abstract [en]

    This contribution treats the latest developments in the understanding of basic principles regarding device design, transduction mechanisms, gas-materials-interactions, and materials processing for the tailored design and fabrication of SiC FET gas sensor devices, mainly intended as products for the automotive sector.

  • 22.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Pearce, Ruth
    National Physical Laboratory, Teddington, Middlesex, UK.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    New generation SiC based field effect transistor gas sensors2013In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 179, no SI, p. 95-106Article in journal (Refereed)
    Abstract [en]

    With the advances in SiC processing and high temperature packaging technology over the past few years as well as the accumulation of knowledge regarding the sensing characteristics of different gate metal/insulator material combinations for different gaseous substances SiC based field effect high temperature sensors are moving towards commercial maturity. The route towards commercialization has, however, also led to the necessity of making new considerations regarding the basic transducer design and operation. The focus of this paper is thus the investigation of some basic transducer related parameters influence on sensor device performance, e.g. sensitivity and long-term stability, and characteristics to exemplify the importance of taking design, processing and operation parameters into account when developing field effect sensor devices for commercial applications. less thanbrgreater than less thanbrgreater thanTwo different types of devices, enhancement and depletion type MISFET sensors, with different gate dimensions and two different gate metallisations, Pt and Ir, have been processed. I/V-characteristics have been obtained under exposure to various concentrations of H-2, NH3, CO and O-2 and different bias conditions and the influence of gate dimensions and bias conditions on the sensitivity and dynamic range investigated. The long-term stability has also been studied and compared between different devices and bias conditions for conceptually different gas compositions. The results show that the type of basic transducer device, its design and mode of operation has a large influence on sensor performance. Depletion type devices offer better possibilities for tuning of sensitivity and dynamic range as well as improved longterm stability properties, whereas enhancement type devices require much less control of the processing to ensure good repeatability and yield. Some results have also been verified for two possible applications of SiC based field effect sensors, ammonia slip monitoring for the control of SCR/SNCR and combustion control in domestic/district heating facilities.

  • 23.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Petersson, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Padban, Nader
    TPS Termiska Processer AB, Studsvik, Nyköping, Sweden.
    Larfeldt, Jenny
    TPS Termiska Processer AB, Studsvik, Nyköping, Sweden.
    Holmberg, Martin
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    SiC-FE gas sensor based combustion control in domestic heating systems, characteristics and utility2007Manuscript (preprint) (Other academic)
    Abstract [en]

    SiC based field effect gas sensors have been evaluated for future possible use in combustion control schemes for domestic heating systems. Emphasis has been on the possibility to monitor the state of combustion and follow the development of the combustion process from an emissions point of view and to determine its cause. The sensor signals have been compared to true emissions data – CO and total hydrocarbon concentration – as obtained by an IR spectrometer and a flame ionization detector (FID) as well as flue gas concentration of oxygen as obtained by a paramagnetic cell. The sensor characteristics have been evaluated using multivariate statistics and the results suggest that, by using the signals from one or more SiC-based field effect sensors and a thermocouple, it seems possible to provide a rough picture of the state of combustion applicable to a control scheme in order to reduce emissions and increase the power to fuel economy.

  • 24.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Petersson, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Pardban, N.
    TPS Termiska Processer AB, Nyköping, Sweden.
    Larfeldt, J.
    TPS Termiska Processer AB, Nyköping, Sweden.
    Holmberg, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    The characteristics and utility of SiC-FE gas sensors for control of combustion in domestic heating systems [MISFET sensors]2004In: Proceedings of IEEE Sensors, 2004., 2004, p. 1157-1160Conference paper (Refereed)
    Abstract [en]

    The possible utility of MISiCFET gas sensors in the application of combustion control in small-scale boilers has been tested and compared to commercially available resistive-type MOS sensors. The results suggest that by using the signals from one or more MISiCFET sensors, together with the measured temperature of the furnace, it seems possible to provide a rough picture of the state of combustion applicable to a control scheme in order to reduce emissions and increase the power to fuel economy.

  • 25.
    Andersson, Mike
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Wingbrant, Helena
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Study of CO response of SiC based field effect gas sensors2005In: IEEE Sensors 2005,2005, 2005, p. 105-Conference paper (Refereed)
  • 26.
    Arbab, A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Evaluation of gas mixtures with high-temperature gas sensors based on silicon carbide1994In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 19, no 1-3, p. 562-565Article in journal (Refereed)
    Abstract [en]

    Field-effect devices with a catalytic metal gate are operated as gas sensors over a large temperature range by the use of 6H-silicon carbide (bandgap 2.9 eV) instead of silicon (1.1 eV) as the semiconducting material. We have produced metal-silicon dioxide-silicon carbide (MOSiC) capacitors with platinum as the gate metal that can be operated above 800-degrees-C. The sensitivity of the Pt-MOSiC devices to hydrogen and hydrocarbons was tested in various oxygen atmospheres. The response to mixtures of hydrogen and saturated hydrocarbons indicated the existence of two different sensing mechanisms.

  • 27.
    Arbab, A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Gas sensors for high temperature operation based on metal oxide silicon carbide (MOSiC) devices1993In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 15, no 1-3, p. 19-23Article in journal (Refereed)
    Abstract [en]

    Catalytic metal gate-silicon dioxide-silicon carbide (MOSiC) capacitors operating to about 800-degrees-C are used as high temperature gas sensor devices. Hydrogen or hydrogen containing molecules, which are dissociated on the catalytic metal surface, create a decrease of the flat band voltage of the MOS capacitor. The MOSiC devices with a platinum gate respond to saturated hydrocarbons in air at concentrations well below the explosion limits.

  • 28.
    Asres, Georgies Alene
    et al.
    Univ Oulu, Finland.
    Baldovi, Jose J.
    Max Planck Inst Struct and Dynam Matter, Germany; Univ Basque Country, Spain.
    Dombovari, Aron
    Univ Oulu, Finland.
    Jarvinen, Topias
    Univ Oulu, Finland.
    Lorite, Gabriela Simone
    Univ Oulu, Finland.
    Mohl, Melinda
    Univ Oulu, Finland.
    Shchukarev, Andrey
    Umea Univ, Sweden.
    Perez Paz, Alejandro
    Univ Basque Country, Spain; Yachay Tech Univ, Ecuador.
    Xian, Lede
    Max Planck Inst Struct and Dynam Matter, Germany; Univ Basque Country, Spain.
    Mikkola, Jyri-Pekka
    Umea Univ, Sweden; Abo Akad Univ, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Univ Oulu, Finland.
    Jantunen, Heli
    Univ Oulu, Finland.
    Rubio, Angel
    Max Planck Inst Struct and Dynam Matter, Germany; Univ Basque Country, Spain.
    Kordas, Krisztian
    Univ Oulu, Finland.
    Ultrasensitive H2S gas sensors based on p-type WS2 hybrid materials2018In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 11, no 8, p. 4215-4224Article in journal (Refereed)
    Abstract [en]

    Owing to their higher intrinsic electrical conductivity and chemical stability with respect to their oxide counterparts, nanostructured metal sulfides are expected to revive materials for resistive chemical sensor applications. Herein, we explore the gas sensing behavior of WS2 nanowire-nanoflake hybrid materials and demonstrate their excellent sensitivity (0.043 ppm(-1)) as well as high selectivity towards H2S relative to CO, NH3, H-2, and NO (with corresponding sensitivities of 0.002, 0.0074, 0.0002, and 0.0046 ppm(-1), respectively). Gas response measurements, complemented with the results of X-ray photoelectron spectroscopy analysis and first-principles calculations based on density functional theory, suggest that the intrinsic electronic properties of pristine WS2 alone are not sufficient to explain the observed high sensitivity towards H2S. A major role in this behavior is also played by O doping in the S sites of the WS2 lattice. The results of the present study open up new avenues for the use of transition metal disulfide nanomaterials as effective alternatives to metal oxides in future applications for industrial process control, security, and health and environmental safety.

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  • 29.
    Asres, Georgies Alene
    et al.
    Univ Oulu, Finland.
    Jarvinen, Topias
    Univ Oulu, Finland.
    Lorite, Gabriela S.
    Univ Oulu, Finland.
    Mohl, Melinda
    Univ Oulu, Finland.
    Pitkanen, Olli
    Univ Oulu, Finland.
    Dombovari, Aron
    Univ Oulu, Finland.
    Toth, Geza
    VTT Finland, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Univ Oulu, Finland.
    Vajtai, Robert
    Rice Univ, TX 77005 USA.
    Ajayan, Pulickel M.
    Rice Univ, TX 77005 USA.
    Lei, Sidong
    Univ Calif Los Angeles, CA 90095 USA.
    Talapatra, Saikat
    Southern Illinois Univ, IL 62901 USA.
    Kordas, Krisztian
    Univ Oulu, Finland.
    High photoresponse of individual WS2 nanowire-nanoflake hybrid materials2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 23, article id 233103Article in journal (Refereed)
    Abstract [en]

    van der Waals solids have been recognized as highly photosensitive materials that compete conventional Si and compound semiconductor based devices. While 2-dimensional nanosheets of single and multiple layers and 1-dimensional nanowires of molybdenum and tungsten chalcogenides have been studied, their nanostructured derivatives with complex morphologies are not explored yet. Here, we report on the electrical and photosensitive properties of WS2 nanowire-nanoflake hybrid materials we developed lately. We probe individual hybrid nanostructured particles along the structure using focused ion beam deposited Pt contacts. Further, we use conductive atomic force microscopy to analyze electrical behavior across the nanostructure in the transverse direction. The electrical measurements are complemented by in situ laser beam illumination to explore the photoresponse of the nanohybrids in the visible optical spectrum. Photodetectors with responsivity up to similar to 0.4 AW(-1) are demonstrated outperforming graphene as well as most of the other transition metal dichalcogenide based devices. Published by AIP Publishing.

  • 30.
    Assadi, A.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Willander, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Svensson, Christer
    Linköping University, Department of Science and Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Interaction of planar polymer Schottky barrier diodes with gaseous substances1994In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 20, no 1, p. 71-77Article in journal (Refereed)
    Abstract [en]

    Conducting polymers appear very attractive as sensor materials either as the gas-sensitive component or as a matrix for easy immobilization of a specific substrate. The planar Schottky barrier diode with poly(3-octylthiophene), P3OT, as the semiconductor is used as a sensor for the detection of different gas species. The shifts in the current-voltage (C-V) characteristics as well as the C-V characteristics of the diodes due to water and ethanol vapour, ammonia gas and nitric oxide gases are studied. Nitric oxide and ammonia give the largest and most specific changes of the C-V characteristics. Nitric oxide has a doping effect, which increases the reverse current, while ammonia is the only gas that causes a negative change in the forward bias current of the I-V curve. The planar configuration of the Schottky barrier diode facilitates the absorption of gaseous species in the environment, and provides a simple method for production of gas sensors.

  • 31.
    Baranzahi, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Andersson, B.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Gas sensitive field effect devices for high temperature1995In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 26, no 1-3, p. 165-169Article in journal (Refereed)
    Abstract [en]

    Field effect sensors based on metal-oxide-silicon carbide (MOSiC) devices are used as high temperature gas sensors. They are sensitive to, for example, saturated hydrocarbons and hydrogen and can be operated up to at least 800 degrees C, which make them suitable for several types of combustion control. A metal gate with two layer platinum and a buffer layer of tantalum silicide in between gave a large increase in the long term stability of the sensors. At temperatures below 600 degrees C, the response to ethane in oxygen was shown to have a threshold at a ratio of about 0.38 for the ethane-to-oxygen concentrations. Below this ratio, the surface can be considered as mainly oxygen covered and the response is small. Above this ratio the metal surface is probably mainly hydrogen covered and the response is considerably larger.

  • 32.
    Baranzahi, Amir
    et al.
    Linköping University, Department of Science and Technology, Physics and Electronics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Glavmo, M
    Mecel AB, Åmål, Sweden; AB Volvo Technol Dev, Gothenburg, Sweden.
    Carlsson, C
    Mecel AB, Åmål, Sweden; AB Volvo Technol Dev, Gothenburg, Sweden.
    Nytomt, J
    Mecel AB, Åmål, Sweden; AB Volvo Technol Dev, Gothenburg, Sweden.
    Salomonsson, P
    Mecel AB, Åmål, Sweden; AB Volvo Technol Dev, Gothenburg, Sweden.
    Jobson, E
    Mecel AB, Åmål, Sweden; AB Volvo Technol Dev, Gothenburg, Sweden.
    Haggendal, B
    Mecel AB, Åmål, Sweden; AB Volvo Technol Dev, Gothenburg, Sweden.
    Martensson, P
    Mecel AB, Åmål, Sweden; AB Volvo Technol Dev, Gothenburg, Sweden.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Biosensors and Bioelectronics. Linköping University, The Institute of Technology.
    Response of metal-oxide-silicon carbide sensors to simulated and real exhaust gases1997In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 43, no 1-3, p. 52-59Article in journal (Refereed)
    Abstract [en]

    Field effect devices based on catalytic metal-oxide-silicon carbide (MOSiC) structures can be used as high temperature gas sensors. The devices are sensitive to hydrocarbons and hydrogen and can be operated up to at least 900 degrees C, which make them suitable for several combustion applications, Simulated and real exhaust gases from a car engine have been studied at sensor temperatures from 200 to 650 degrees C, and it was round that the sensor signal is high for excess hydrocarbon and low for excess oxygen. The response time is less than 100 ms and only a small degradation of the devices was observed after several days of operation. The devices also react to changes of the gas composition In the fuel-rich and fuel-lean region. The devices show an interesting temperature dependence in the fuel rich region.

  • 33.
    Baranzahi, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Reversible hydrogen annealing of metal‐oxide‐silicon carbide devices at high temperatures1995In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 67, no 21, p. 3203-3205Article in journal (Refereed)
    Abstract [en]

    We report on a reversible hydrogen annealing effect observed in platinum-silicon dioxide-silicon carbide structures at temperatures above about 650 degrees C. It appears as a decrease of the inversion capacitance in the presence of hydrogen. This phenomenon is shown to depend on hydrogen atoms, created on the catalytic metal, that pass through the oxide and interact with charge generation sites at the oxide-silicon carbide interface. The consequence of the observation for chemical sensors based on silicon carbide is discussed. The results are phenomenological, since no details of the annealing chemistry could be developed from the present experiments. We find, however, that the annealing process and its reversal have activation energies of about 0.9 eV and 2.9 eV/site,respectively.

  • 34.
    Baranzahi, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Tobias, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Mårtensson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ekedahl, Lars Gunnar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Chemical sensors with catalytic metal gates - Switching behavior and kinetic phase transitions1998In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 145, no 10, p. 3401-3406Article in journal (Refereed)
    Abstract [en]

    Rapid transitions in the response of platinum-based chemical sensors occurring at given hydrogen-oxygen concentration ratios are explained by kinetic phase transitions or switching phenomena on the catalytic metal surface. Below the transition point the response of platinum-insulator silicon carbide devices is small and above the transition it is large. It is found that the critical ratio depends on the operation temperature and the properties of the device. Three different cases are identified, namely, injection-, diffusion-, and reaction-rate-determined transitions. At sufficiently large temperatures the transition is injection limited and occurs at the stoichiometric ratio of hydrogen and oxygen in the gas mixture. The implications of the experimental observations on the applications of chemical sensors with catalytic sensing layers are discussed.

  • 35.
    Baranzahi, Amir
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Tobias, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Mårtensson, Per
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ekedahl, Lars-Gunnar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Kinectic phase transitions and chemical sensors with catalytic metal gates1997In: Chemical & Biological Sensors & Analytical Electrochemical Methods, 1997, Electrochemical Society , 1997, Vol. 97, no 19, p. 1-15Conference paper (Other academic)
    Abstract [en]

    Rapid transitions in the response of platinum based chemical sensors occurring at given hydrogen-oxygen concentration ratios are explained by kinetic phase transitions or switching phenomena on the catalytic metal surface. Below the transition point the response of platinum-insulator silicon carbide devices is small and above the transition large and almost saturated. It is found that the critical ratio depends on the operation temperature and the properties of the device. Three different cases are identified, namely injection-, diffusion- and reaction rate determined transitions. At sufficiently large temperatures the transition is injection limited and occurs at the stoichiometric ratio of hydrogen and oxygen in the gas mixture. The implications of the experimental observations on the applications of chemical sensors with catalytic sensing layers are discussed.

  • 36.
    Bastuck, Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. University of Saarland, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Huotari, J.
    University of Oulu, Finland.
    Sauerwald, T.
    University of Saarland, Germany.
    Lappalainen, J.
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Schuetze, A.
    University of Saarland, Germany.
    Exploring the selectivity of WO3 with iridium catalyst in an ethanol/naphthalene mixture using multivariate statistics2016In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 618, p. 263-270Article in journal (Refereed)
    Abstract [en]

    Temperature cycled operation and multivariate statistics have been used to compare the selectivity of two gate (i.e. sensitive) materials for gas-sensitive, silicon carbide based field effect transistors towards naphthalene and ethanol in different mixtures of the two substances. Both gates have a silicon dioxide (SiO2) insulation layer and a porous iridium (Ir) electrode. One of it has also a dense tungsten trioxide (WO3) interlayer between Ir and SiO2. Both static and transient characteristics play an important role and can contribute to improve the sensitivity and selectivity of the gas sensor. The Ir/SiO2 is strongly influenced by changes in ethanol concentration, and is, thus, able to quantify ethanol in a range between 0 and 5 ppm with a precision of 500 ppb, independently of the naphthalene concentrations applied in this investigation. On the other hand, this sensitivity to ethanol reduces its selectivity towards naphthalene, whereas Ir/WO3/SiO2 shows an almost binary response to ethanol. Hence, the latter has a better selectivity towards naphthalene and can quantify legally relevant concentrations down to 5 ppb with a precision of 2.5 ppb, independently of a changing ethanol background between 0 and 5 ppm. (C) 2016 Elsevier B.V. All rights reserved.

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  • 37.
    Bastuck, Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. University of Saarland, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Schuetze, A.
    University of Saarland, Germany.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Characterizing the Influence of Gate Bias on Electrical and Catalytical Properties of a Porous Platinum Gate on Field Effect Gas Sensors2016In: 2016 IEEE SENSORS, IEEE , 2016Conference paper (Refereed)
    Abstract [en]

    In this work, we exposed an MIS capacitor with porous platinum as gate material to different concentrations of CO and NH3. Its capacitance and typical reaction products (water, CO2 and NO) were monitored at high and low oxygen concentration and different gate bias voltages. We found that the gate bias influences the switch-point of the binary CO response usually seen when either changing the temperature at constant gas concentrations or the CO/O-2 ratio at constant temperature. For NH3, the sensor response as well as product reaction rates increase with bias voltages up to 6 V. A capacitance overshoot is observed when switching on or off either gas at low gate bias, suggesting increasing oxygen surface coverage with decreasing gate bias.

  • 38.
    Bastuck, Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Saarland University, Lab for Measurement Technology, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Schuetze, Andreas
    Saarland University, Saarbrücken, Germany.
    Sauerwald, Tilman
    Saarland University, Saarbrücken, Germany.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    UV-assisted gate bias cycling in gas-sensitive field-effect transistors2018In: Proceedings, ISSN 2504-3900, Vol. 2, no 13, article id 999Article in journal (Refereed)
    Abstract [en]

    Static and dynamic responses of a silicon carbide field-effect transistor gas sensor have been investigated at two different gate biases in several test gases. Especially the dynamic effects are gas dependent and can be used for gas identification. The addition of ultraviolet light reduces internal electrical relaxation effects, but also introduces new, temperature-dependent effects.

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  • 39.
    Bastuck, Manuel
    et al.
    Saarland University, Lab for Measurement Technology, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Reimringer, Wolfhard
    3S GmbH, Saarbrücken, Germany.
    Schuetze, Andreas
    Saarland University, Germany.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Low-cost chemical gas sensors for selective formaldehyde quantification at ppb-level in field tests2017Conference paper (Refereed)
    Abstract [en]

    Data from a silicon carbide based field-effect transistor were recorded over a period of nine days in a ventilated school room. For enhanced sensitivity and selectivity especially to formaldehyde, porous iridium on pulsed laser deposited tungsten trioxide was used as sensitive layer, in combination with temperature cycled operation and subsequent multivariate data processing techniques. The sensor signal was compared to reference measurements for formaldehyde concentration, CO2 concentration, temperature, and relative humidity. The results show a distinct pattern for the reference formaldehyde concentration, arising from the day/night cycle. Taking this into account, the projections of both principal component analysis and partial least squares regression lead to almost the same result concerning correlation to the reference. The sensor shows cross-sensitivity to an unidentified component of human activity, presumably breath, and, possibly, to other compounds appearing together with formaldehyde in indoor air. Nevertheless, the sensor is able to detect and partially quantify formaldehyde below 40 ppb with a correlation to the reference of 0.48 and negligible interference from ambient temperature or relative humidity.

  • 40.
    Bastuk, Emanuel
    et al.
    Saarland University, Saarbruecken, Germany.
    Bur, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Saarbruecken, Germany.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Identification of ammonia and carbon monoxide based on the hysteresis of a gas sensitive silicon carbide field effect transistor2013In: Transducers 2013 & Eurosensors XXVII, IEEE , 2013, p. 250-253Conference paper (Refereed)
    Abstract [en]

    In this work gate bias cycled operation (GBCO) is used on a gas-sensitive SiC field effect transistor(“GasFET”) to increase the sensitivity and selectivity. Gate bias ramps introduce strong hysteresis in the sensor signal. The shape of this hysteresis is shown to be an appropriate feature both for the discrimination of various gases (NH3, CO, NO, CH4) and also different gas concentrations (250 and 500 ppm). The shape is very sensitive to ambient conditions. Thus, the influence of oxygen concentration and relative humidity as well as sensor temperature is investigated and reasons for the observed signal changes are discussed.

  • 41.
    Bastuk, Manuel
    et al.
    Saarland University, Saarbruecken, Germany.
    Bur, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Saarbruecken, Germany.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Gas identification based on bias induced hysteresis of a gas-sensitive SiC field effect transistor2014In: Journal of Sensors and Sensor Systems, ISSN 2194-8771, Vol. 3, p. 9-19Article in journal (Refereed)
    Abstract [en]

    In this work dynamic variation of gate bias is used on a gas-sensitive SiC field effect transistor ("GasFET") to optimize its sensitivity and increase its selectivity. Gate bias ramps introduce strong hysteresis in the sensor signal. The shape of this hysteresis is shown to be an appropriate feature both for the discrimination of various gases (ammonia, carbon monoxide, nitrogen monoxide and methane) as well as for different gas concentrations (250 and 500 ppm). The shape is very sensitive to ambient conditions as well as to the bias sweep rate. Thus, the influences of oxygen concentration, relative humidity, sensor temperature and cycle duration, i.e., sweep rate, are investigated and reasons for the observed signal changes, most importantly the existence of at least two different and competing processes taking place simultaneously, are discussed. Furthermore, it is shown that even for very fast cycles, in the range of seconds, the gas-induced shape change in the signal is strong enough to achieve a reliable separation of gases using gate bias cycled operation and linear discriminant analysis (LDA) making this approach suitable for practical application.

  • 42.
    Basu, P. K.
    et al.
    Jadavpur University.
    Saha, N.
    Jadavpur University.
    Jana, S. K.
    Jadavpur University.
    Saha, H.
    Jadavpur University.
    Spetz Lloyd, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Basu, S.
    Jadavpur University.
    Schottky Junction Methane Sensors using Electrochmically Grown Nanocrystalline-Nanoporous ZnO Thin Films2009In: Journal of Sensors, Vol. 2009, no 790476, p. 1-9Article in journal (Other academic)
    Abstract [en]

    Nanocrystalline-nanoporous ZnO thin films were prepared by an electrochemical anodization method, and the films were tested as methane sensors. It was found that Pd-Ag catalytic contacts showed better sensing performance compared to other noble metal contacts like Pt and Rh. The methane sensing temperature could be reduced to as low as 100°C by sensitizing nanocrystalline ZnO thin films with Pd, deposited by chemical method. The sensing mechanism has been discussed briefly.

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  • 43.
    Becker, Elin
    et al.
    Competence Centre for Catalysis and the Department Chemical and Biological Engineering, Chalmers, University of Technology, Gothenburg.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Eriksson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Skoglundh, Magnus
    Competence Centre for Catalysis and the Department Chemical and Biological Engineering, Chalmers, University of Technology, Gothenburg.
    Study of the Sensing Mechanism Towards Carbon Monoxide of Platinum-Based Field Effect Sensors2011In: IEEE SENSORS JOURNAL, ISSN 1530-437X, Vol. 11, no 7, p. 1527-1534Article in journal (Refereed)
    Abstract [en]

    We have investigated the temperature dependence and the effect of hydrogen on the CO response of MISiC field effect device sensors. The evolution of adsorbates on a model sensor was studied by in situ DRIFT spectroscopy and correlated to sensor response measurements at similar conditions. A strong correlation between the CO coverage of the sensor surface and the sensor response was found. The temperature dependence and hydrogen sensitivity are partly in agreement with these observations, however at low temperatures it is difficult to explain the observed increase in sensor response with increasing temperature. This may be explained by the reduction of a surface oxide or removal of oxygen from the Pt/SiO2 interface at increasing temperatures. The sensing mechanism of MISiC field effect sensors is likely complex, involving several of the factors discussed in this paper.

  • 44.
    Bjorklund, Robert
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    W. Grant, Ann
    Volvo Technology, Göteborg.
    Jozsa, Peter
    Volvo Technology, Göteborg.
    Johansson, Mats
    VOLVO Cars Cororation, Göteborg.
    Fägerman, Per-Erik
    Mandalon Technologies, Linköping.
    Paaso, Jaska
    Selmic Oy, Oulu, Finland.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Hammarlund, Lars
    SenSiC AB, Stockholm.
    Larsson, Andreas
    SINTEF, Oslo, Norway.
    Popovici, Eveline
    University of Iasi, Romania.
    Lutic, Doina
    University of Iasi, Romania.
    Pagel, Joakim
    Lund University, Institutionen för designvetenskaper.
    Sanati, Mehri
    Lund University, Institutionen för designvetenskaper.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Soot sensor based on thermophoresis for high sensitive soot detection in diesel exhausts2010In: IMCS13, 2010, p. 250-Conference paper (Refereed)
  • 45.
    Bohme, O
    et al.
    Tech Univ Cottbus, D-03044 Cottbus, Germany Linkoping Univ, Swedish Sensor Ctr, S-58183 Linkoping, Sweden.
    Lloyd-Spets, Anita
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Schmeisser, D
    Tech Univ Cottbus, D-03044 Cottbus, Germany Linkoping Univ, Swedish Sensor Ctr, S-58183 Linkoping, Sweden.
    Nanoparticles as the active element of high-temperature metal-insulator-silicon carbide gas sensors2001In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 13, no 8, p. 597-+Article in journal (Refereed)
    Abstract [en]

    The sensor performance of MISiC (metal-insulator-silicon carbide) diode devices depends on their temperature pretreatment: an activation step at 600 degreesC leads to fast-responding devices with extraordinarily high signals but the devices fail when operated above 700 degreesC. The authors focus on the key role of nanoparticles in high-temperature gas sensor applications of these MISiC devices, presenting a model in which the interface dipole moment of nanoparticles is seen as the driving force and explaining the difference in response of capacitor-configuration and Schottky-diode-configuration devices.

  • 46.
    Bounechada, Djamela
    et al.
    Chalmers, Dept Chem & Biol Engn, SE-41296 Gothenburg, Sweden Chalmers, Competence Ctr Catalysis, SE-41296 Gothenburg, Sweden .
    Darmastuti, Zhafira
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Skoglundh, Magnus
    Chalmers, Dept Chem & Biol Engn, SE-41296 Gothenburg, Sweden Chalmers, Competence Ctr Catalysis, SE-41296 Gothenburg, Sweden.
    Carlsson, Per-Anders
    Chalmers, Dept Chem & Biol Engn, SE-41296 Gothenburg, Sweden Chalmers, Competence Ctr Catalysis, SE-41296 Gothenburg, Sweden.
    Vibrational Study of SOx Adsorption on Pt/SiO22014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 51, p. 29713-29723Article in journal (Refereed)
    Abstract [en]

    The formation of ad-SOx species on Pt/SiO2 upon exposure to SO2 in concentrations ranging from 10 to 50 ppm at between 200 and 400 degrees C has been studied by in situ diffuse reflectance infrared Fourier transformed spectroscopy. In parallel, first-principles calculations have been carried out to consolidate the experimental interpretations. It was found that sulfate species form on the silica surface with a concomitant removal/rearrangement of silanol groups. Formation of ad-SOx species occurs only after SO2 oxidation to SO3 on the platinum surface. Thus, SO2 oxidation to SO3 is the first step in the SOx adsorption process, followed by spillover of SO3 to the oxide, and finally, the formation of sulfate species on the hydroxyl positions on the oxide. The sulfate formation is influenced by both temperature and SO2 concentration. Furthermore, exposure to hydrogen is shown to be sufficiently efficient as to remove ad-SOx species from the silica surface.

  • 47.
    Bounechada, Djamela
    et al.
    Chalmers Institute of Technology, Gothenburg.
    Darmastuti, Zhafira
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Ojamae, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Skoglundh, Magnus
    Competence Centre for Catalysis / Department of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Carlsson, P-A
    Competence Centre for Catalysis / Department of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Vibrational analysis of SO2 on Pt / SiO2 systemManuscript (preprint) (Other academic)
    Abstract [en]

    In situ diffuse reflectance infrared Fourier transformed spectroscopy was used to study the interactions of SOx species with Pt/SiO2 between 200 and 400°C, and for SO2 concentrations between 10 and 50 ppm, which represents a concentration range where MISFET sensors exhibit good responses. In parallel, first-principles calculations have been carried out to support the experimental interpretations. It was found that sulfate species were formed on the silica surface, accompanied with removal/rearrangement of silanol groups upon exposure to SO2. Both experimental and theoretical calculations also suggest that the surface species were only formed after SO2 oxidation to SO3 on the metal surface. These evidences support the idea of SO2 oxidation to SO3 as the first step in the process of sulfate formation, followed by spillover of SO3 to the oxide, and finally the formation of sulfate species on the hydroxyl positions on the oxide. The results also indicate that the sulfate formation on silica depends both on the temperature and the SO2 concentration. Furthermore, hydrogen exposure was shown to be efficient for sulfur removal from the silica surface.

  • 48.
    Buchholt, Kristina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ghandi, R
    Royal Institute Technology, KTH.
    Domeij, M
    Royal Institute Technology, KTH.
    Zetterling, C M
    Royal Institute Technology, KTH.
    Behan, G
    Trinity College Dublin.
    Zhang, H
    Trinity College Dublin.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Growth and characterization of epitaxial Ti3GeC2 thin films on 4H-SiC(0001)2012In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 343, no 1, p. 133-137Article in journal (Refereed)
    Abstract [en]

    Epitaxial Ti3GeC2 thin films were deposited on 4 degrees off-cut 4H-SiC(0001) using magnetron sputtering from high purity Ti, C, and Ge targets. Scanning electron microscopy and helium ion microscopy show that the Ti3GeC2 films grow by lateral step-flow with {11 (2) over bar0} faceting on the SiC surface. Using elastic recoil detection analysis, atomic force microscopy, and X-Ray diffraction the films were found to be substoichiometric in Ge with the presence of small Ge particles at the surface of the film.

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  • 49.
    Buchholt, Kristina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Step-flow growth of nanolaminate Ti3SiC2 epitaxial layers on 4H-SiC(0 0 0 1)2011In: SCRIPTA MATERIALIA, ISSN 1359-6462, Vol. 64, no 12, p. 1141-1144Article in journal (Refereed)
    Abstract [en]

    Epitaxial Ti3SiC2(0 0 0 1) films were deposited on 4 degrees off-cut 4H-SiC(0 0 0 1) wafers using magnetron sputtering. A lateral step-flow growth mechanism of the Ti3SiC2 was discovered by X-ray diffraction, elastic recoil detection analysis, atomic force microscopy and electron microscopy. Helium ion microscopy revealed contrast variations on the Ti3SiC2 terraces, suggesting a mixed Si and Ti(C) termination. Si-rich growth conditions results in Ti3SiC2 layers with pronounced {1 1 (2) over bar 0) faceting and off-oriented TiSi2 crystallites, while stoichiometric growth yields truncated {1 (1) over bar 0 0) terrace edges.

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  • 50.
    Buchholt, Kristina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ghandi, R
    Royal Institute of Technology.
    Domeij, M
    Royal Institute of Technology.
    Zetterling, C-M
    Royal Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ohmic contact properties of magnetron sputtered Ti3SiC2 on n- and p-type 4H-silicon carbide2011In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, no 4, p. 042108-Article in journal (Refereed)
    Abstract [en]

    Epitaxial Ti3SiC2 (0001) thin film contacts were grown on doped 4H-SiC (0001) using magnetron sputtering in an ultra high vacuum system. The specific contact resistance was investigated using linear transmission line measurements. Rapid thermal annealing at 950 degrees C for 1 min of as-deposited films yielded ohmic contacts to n-type SiC with contact resistances in the order of 10(-4) Omega cm(2). Transmission electron microscopy shows that the interface between Ti3SiC2 and n-type SiC is atomically sharp with evidence of interfacial ordering after annealing.

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    ApplPhysLett
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