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  • 1.
    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, 2859-2868 p.Article 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.

  • 2.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Development and characterization of SiC based field effect gas sensors and sensor systems for emissions monitoring and control of biomass combustion2005Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Increasing oil prices and environmental levies have reinforced the interest in biofuels for domestic and district heating, most commonly through combustion of solid biomass like wood logs, hog fuel and pellets in water based heating systems. The combustion process itself proceeds through three elementarysteps; drying, where fuel moisture is driven off, followed by pyrolysis and finally combustion of the remaining charcoal. Given the sufficient amount of air, good mixing and long enough residence time at elevated temperatures, the short-chained hydrocarbons and carbon monoxide formed during pyrolysis andchar combustion will burn to completion leaving only CO2 and H2O in the flue gases.

    In case of air deficiency, combustion will be incomplete, leaving noxious compounds, like certain hydrocarbons and CO, behind. Too much of excess air, on the other hand, will lower the temperature of the combustion chamber, giving rise to both emissions of unburned material and, due to the forcedconvection of heat out the chimney, an impaired boiler efficiency. The key to boiler operation, both from an environmental as well as a power to fuel economy point of view, is thus the careful adjustment of the airflows during combustion. The amount of air needed for complete oxidation of the fuel varies with the phase of combustion, fuel, fuel quality and load, however, why an active control of the airflows is considered a prerequisite. So far, nocontrol schemes have been applied to small- and medium-sized combustors, though, mainly dependent on the lack of cheap and simple means to measure basic flue gas parameters, like oxygen, hydrocarbons and CO.

    Here is reported about the possible use of a system comprising SiC based field effect sensors to monitor the state of combustion, applicable to domestic heating systems, where only a rough picture of the air to fuel relationship is needed. Furthermore, it has been shown possible to obtain a multivariate linear regression model for propene (a model hydrocarbon) by the application of an array of SiC field effect sensors in a varying background of typical flue gas constituents, as long as thevariation is not too large. This model could possibly be applied to a control scheme for medium sized boilers, where smaller variations of flue gas constituents are encountered, and the possibility of simultaneous ammonia estimations has also opened up the field of flue gas after-treatment controlapplications, monitoring ammonia slip from selective noncatalytic reduction of nitrogen oxides by ammonia. The quantitative estimation of hydrocarbons over a wider range of concentrations and backgrounds, as well as of minor flue gasspecies, NO and CO, is however not possible with the SiC sensors currently comprising the sensor system.

    List of papers
    1. Investigations on the possibilities of a MISiCFET sensor system for OBD and combustion control utilizing different catalytic gate materials
    Open this publication in new window or tab >>Investigations on the possibilities of a MISiCFET sensor system for OBD and combustion control utilizing different catalytic gate materials
    Show others...
    2004 (English)In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 30-31, no 1, 365-368 p.Article in journal (Refereed) Published
    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.

    Keyword
    platinum, iridium, sensor system, field effect sensors, SiC, OBD, combustion control, car exhaust, flue gases
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13092 (URN)10.1023/B:TOCA.0000029776.18603.74 (DOI)
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2017-12-13Bibliographically approved
    2. The characteristics and utility of SiC-FE gas sensors for control of combustion in domestic heating systems [MISFET sensors]
    Open this publication in new window or tab >>The characteristics and utility of SiC-FE gas sensors for control of combustion in domestic heating systems [MISFET sensors]
    Show others...
    2004 (English)In: Proceedings of IEEE Sensors, 2004., 2004, 1157-1160 p.Conference paper, Published 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.

    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-101348 (URN)10.1109/ICSENS.2004.1426382 (DOI)0-7803-8692-2 (ISBN)
    Conference
    Third IEEE International Conference on Sensors, Vienna, Austria, October 24-27 (2004)
    Available from: 2013-11-21 Created: 2013-11-21 Last updated: 2014-01-09
  • 3.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    SiC based field effect sensors and sensor systems for combustion control applications2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Increasing oil prices and concerns about global warming have reinforced the interest in biofuels for domestic and district heating, most commonly through combustion of solid biomass like wood logs, hog fuel and pellets. Combustion at non-optimal conditions can, however, lead to substantial emissions of noxious compounds like unburned hydrocarbons, carbon monoxide, and nitrogen oxides as well as the generation of soot.

    Depending on the rate of combustion more or less air is needed per unit time to completely oxidize the fuel; deficiency of air leading to emissions of unburned matter and too much of excess air to slow combustion kinetics and emissions of mainly carbon monoxide. The rate of combustion is influenced by parameters like fuel quality – moisture and ash content etc. – and in what phase the combustion takes place (in the gas phase through combustion of evaporated substances or on the surface of char coal particles), none of which is constant over time.

    The key to boiler operation, both from an environmental as well as a power to fuel economy point of view, is thus the careful adjustment of the air supply throughout the combustion process. So far, no control schemes have been applied to small-scale combustors, though, mainly due to the lack of cheap and simple means to measure basic flue gas parameters like oxygen, total hydrocarbon, and carbon monoxide concentrations.

    This thesis reports about investigations on and characterization of silicon carbide (SiC) based Metal Insulator Semiconductor (MIS) field effect gas sensors regarding their utility in emissions monitoring and combustion control applications as well as the final development of a sensor based control system for wood fired domestic heating systems.

    From the main sensitivity profiles of such sensor devices, with platinum (Pt) and iridium (Ir) as the catalytic metal contacts (providing the gas sensing ability), towards some typical flue gas constituents as well as ammonia (NH3), a system comprising four individual sensors operated at different temperatures was developed, which through the application of Partial Least Squares (PLS) regression, showed good performance regarding simultaneous monitoring of propene (a model hydrocarbon) and ammonia concentrations in synthetic flue gases of varying content. The sensitivity to CO was, however, negligible. The sensor system also performed well regarding ammonia slip monitoring when tested in real flue gases in a 5.6 MW boiler running SNCR (Selective Non-Catalytic reduction of nitrogen oxides with ammonia).

    When applied to a 200 kW wood pellet fuelled boiler a similar sensor system was, however, not able to follow the flue gas hydrocarbon concentration in all encountered situations. A PCA (Principal Components Analysis) based scheme for the manipulation of sensor and flue gas temperature data, enabling monitoring of the state of combustion (deficiency or too much of excess air), was however possible to develop. The discrepancy between laboratory and field test results was suspected and later on shown to depend on the larger variation in CO and oxygen concentrations in the flue gases as compared to the laboratory tests.

    Detailed studies of the CO response characteristics for Pt gate MISiC sensors revealed a highly non-linear sensitivity towards CO, a large response only encountered at high CO/O2 ratios or low temperatures. The response exhibits a sharp switch between a small and a large value when crossing a certain CO/O2 ratio at constant operating temperature, correlated to the transition from an oxygen dominated to an almost fully CO covered Pt surface, originating from the difference in adsorption kinetics between CO and O2. Indications were also given pointing towards an increased sensitivity to background hydrogen as being the mediator of at least part of the CO response. Some general characteristics regarding the response mechanism of field effect sensors with differently structured metal contacts were also indicated.

    The CO response mechanism of Pt metal MISiC sensors could also be utilized in developing a combustion control system based on two sensors and a thermocouple, which when tested in a 40 kW wood fired boiler exhibited a good performance for fuels with extremely low to normal moisture content, substantially decreasing emissions of unburned matter.

    List of papers
    1. Investigations on the possibilities of a MISiCFET sensor system for OBD and combustion control utilizing different catalytic gate materials
    Open this publication in new window or tab >>Investigations on the possibilities of a MISiCFET sensor system for OBD and combustion control utilizing different catalytic gate materials
    Show others...
    2004 (English)In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 30-31, no 1, 365-368 p.Article in journal (Refereed) Published
    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.

    Keyword
    platinum, iridium, sensor system, field effect sensors, SiC, OBD, combustion control, car exhaust, flue gases
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13092 (URN)10.1023/B:TOCA.0000029776.18603.74 (DOI)
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2017-12-13Bibliographically approved
    2. On the applicability of MISiCFET gas sensors regarding ammonia slip monitoring in small-scale boilers running SNCR
    Open this publication in new window or tab >>On the applicability of MISiCFET gas sensors regarding ammonia slip monitoring in small-scale boilers running SNCR
    2007 (English)Manuscript (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.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13093 (URN)
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2016-09-01Bibliographically approved
    3. SiC-FE gas sensor based combustion control in domestic heating systems, characteristics and utility
    Open this publication in new window or tab >>SiC-FE gas sensor based combustion control in domestic heating systems, characteristics and utility
    Show others...
    2007 (English)Manuscript (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.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13094 (URN)
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2016-09-01Bibliographically approved
    4. On the CO response mechanism of SiC based field effect gas sensors
    Open this publication in new window or tab >>On the CO response mechanism of SiC based field effect gas sensors
    (English)Manuscript (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.

    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-13095 (URN)
    Note

    This manuscript was never submitted to a journal and will not be published.

    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2016-06-14Bibliographically approved
    5. On the response mechanism of SiC based field effect gas sensors towards non-hydrogen containing species and specifically NO
    Open this publication in new window or tab >>On the response mechanism of SiC based field effect gas sensors towards non-hydrogen containing species and specifically NO
    (English)Manuscript (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.

    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:liu:diva-13096 (URN)
    Note

    This manuscript was never submitted to a journal and will not be published.

    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2016-06-14Bibliographically approved
    6. A novel sensor system based on gas sensitive MISiCFET devices for combustion control in small-scale wood fired boilers
    Open this publication in new window or tab >>A novel sensor system based on gas sensitive MISiCFET devices for combustion control in small-scale wood fired boilers
    Show others...
    2007 (English)Article in journal (Refereed) Submitted
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:liu:diva-13097 (URN)
    Available from: 2008-04-01 Created: 2008-04-01 Last updated: 2014-01-09
  • 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, 1309-1312 p.Conference 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, 962- p.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, 567-571 p.Article 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, 365-368 p.Article 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, 1320-1323 p.Conference 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, 369- p.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, 189-214 p.Chapter 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, 1028- p.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, 117-158 p.Chapter 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, 365- p.Conference paper (Refereed)
  • 20.
    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, 95-106 p.Article 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.

  • 21.
    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.

  • 22.
    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, 1157-1160 p.Conference 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.

  • 23.
    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, 105- p.Conference paper (Refereed)
  • 24.
    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, 250-253 p.Conference 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.

  • 25.
    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, Vol. 3, 9-19 p.Article 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.

  • 26.
    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, 1527-1534 p.Article 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.

  • 27.
    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, 250- p.Conference paper (Refereed)
  • 28.
    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, 29713-29723 p.Article 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.

  • 29.
    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.

  • 30.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Saarbruecken, Germany.
    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.
    Helwig, Nikolai
    Saarland University, Saarbruecken, Germany.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Detecting Volatile Organic Compounds in the ppb range with platinum-gate SiC-Field Effect Transistors2013In: SENSORS, 2013 IEEE, IEEE , 2013, 1-4 p.Conference paper (Refereed)
    Abstract [en]

    In this work, the use of a platinum gate gas-sensitive SiC Field Effect Transistor (SiC-FET) was studied for the detection of low concentrations of hazardous Volatile Organic Compounds (VOC). For this purpose, a new gas mixing system was built providing VOCs down to sub-ppb levels by permeation ovens and gas pre-dilution. Measurements have shown that benzene, naphthalene and formaldehyde can be detected in the ppb range and indicate a detection limit of 1-2 ppb for benzene and naphthalene. The sensitivity is high with a response of 5.5 mV for 10 ppb naphthalene in a humid atmosphere (at 20% relative humidity) and with additional 2 ppm ethanol the response to naphthalene was still 1.3 mV. Formaldehyde can be detected down to approximately 100 ppb under humid conditions. This is the first time that a metal gated SiC-FET was used to detect hazardous VOCs in the low ppb range making SiC-FETs suitable candidates for indoor air quality applications.

  • 31.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Saarbruecken, Germany.
    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.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Detecting Volatile Organic Compounds in the ppb Range with Gas Sensitive Platinum gate SiC-Field Effect Transistors2014In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 14, no 9, 3221-3228 p.Article in journal (Refereed)
    Abstract [en]

    In this paper, the use of a platinum gate gas-sensitive SiC field-effect transistor (SiC-FET) was studied for the detection of low concentrations of hazardous volatile organic compounds (VOCs). For this purpose, a new gas mixing system was realized providing VOCs down to sub-parts per billion levels with permeation ovens and gas predilution. Benzene, naphthalene, and formaldehyde were chosen as major indoor air pollutants and their characteristics are briefly reviewed. Measurements have shown that the selected VOCs can be detected by the SiC-FET in the parts per billion range and indicate a detection limit of ~1 ppb for benzene and naphthalene and ~10 ppb for formaldehyde in humid atmospheres. For 10-ppb naphthalene at 20% r.h., the sensor response is high with 12 mV, respectively, a relative response of 1.4%. Even in a background of 2-ppm ethanol, the relative response is still 0.3%. Quantification independent of the humidity level can be achieved using temperature cycled operation combined with pattern recognition, here linear discriminant analysis. Discrimination of benzene, naphthalene, and formaldehyde is also possible.

  • 32.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Saarbruecken, Germany.
    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.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Increasing the Selectivity of Pt-Gate SiC FieldEffect Gas Sensors by Dynamic Temperature Modulation2014In: Proc of E-MRS 2014, Lille, France, May 26-30, 2014, 1-9 p.Conference paper (Refereed)
    Abstract [en]

    Based on a diode coupled silicon carbide field effect transistor with platinum as catalytic gate material, the influence of dynamic temperature modulation on the selectivity of GasFETs has been investigated. This operating mode, studied intensively for semiconductor gas sensors, has only recently been applied to field effect transistors. A suitable temperature cycle (T-cycle) for detection of typical exhaust gases (CO, NO, C3H6, H2, NH3) was developed and combined with appropriate signal processing. The sensor data was evaluated using multivariate statistics, e.g. linear discriminant analysis (LDA). Measurements have proven that typical exhaust gases can be discriminated in backgrounds with 0%, 10% and 20% oxygen. Furthermore, we are able to quantify the mentioned gases and to determine unknown concentrations based on training data. Very low levels of relative humidity (r.h.) below a few percent influence the sensor response considerably but for higher levels the cross interference of humidity is negligible. In addition, experiments regarding stability and reproducibility were performed.

  • 33.
    Bur, Christian
    et al.
    Saarland University, Saarbruecken, Germany.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Reimann, P
    Saarland University, Saarbruecken, Germany.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Increasing the selectivity of Pt-gate SiC field effect gas sensors by dynamic temperature modulation2010In: IEEE Sensors 2010, 2010, 1267- p.Conference paper (Refereed)
  • 34.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Saarbruecken, Germany.
    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.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    The influence of gate bias on the CO sensing characteristics of SiC based field effect sensors2014In: Proc of IMCS 2014, Buenos Aires, Argentine, March 17-19, 2014, 133-136 p.Conference paper (Refereed)
    Abstract [en]

    SiC based Field Effect Transistor gas sensors with Pt as gate material have previously been shown to exhibit a binary CO response, sharply switching between a small and a large value with increasing CO or decreasing O2 concentration or temperature. In this study Pt gates with different structures have been fabricated by dc magnetron sputtering at different argon pressures and subjected to various CO/O2 mixtures under various temperatures and gate bias conditions. The influence of gate bias and gate structure on the CO response switch point has been investigated. The results suggest that the more porous the gate material or smaller the bias, the lower the temperature or higher the CO concentration required in order to induce the transition between a small and a large response towards CO. These trends are suggested to reflect the adsorption, spill-over, and reaction characteristics of oxygen chemisorbed to the Pt and insulator surfaces.

  • 35.
    Bur, Christian
    et al.
    Saarland University, Saarbrücken, Germany.
    Bastuck, Manuel
    Saarland University, Saarbrücken,, Germany.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Schütze, Andreas
    Saarland University, Saarbrücken, Germany.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Influence of a Changing Gate Bias on the Sensing Properties of SiC Field Effect Gas Sensors2012In: IMCS 2012, 2012, 140-143 p.Conference paper (Other academic)
    Abstract [en]

    Field effect transistors based on silicon carbide have previously been used with temperature cycled operation to enhance the selectivity. In this study the influence of a changing gate bias on the sensing properties of a platinum gate FET has been studied in order to extend the virtual multi-sensor approach. The sensor exhibits gas specific hysteresis when changing the gate bias indicating that additional information regarding selectivity is contained in the transient behavior. Measurements also showed that especially the shape of the sensor signal changes dramatically with different gas exposures (e.g. H2, CO or NH3) during relaxation after step changes of the gate bias. The changing shape primarily reflects the gas itself and not the concentration so that the selectivity of the sensor is increased.

  • 36.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Bastuck, Manuel
    University of Saarland, 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.
    Schuetze, Andreas
    University of Saarland, Germany .
    Selectivity enhancement of SiC-FET gas sensors by combining temperature and gate bias cycled operation using multivariate statistics2014In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 193, 931-940 p.Article in journal (Refereed)
    Abstract [en]

    In this paper temperature modulation and gate bias modulation of a gas sensitive field effect transistor based on silicon carbide (SiC-FET) are combined in order to increase the selectivity. Data evaluation based on extracted features describing the shape of the sensor response was performed using multivariate statistics, here by Linear Discriminant Analysis (LDA). It was found that both temperature cycling and gate bias cycling are suitable for quantification of different concentrations of carbon monoxide. However, combination of both approaches enhances the stability of the quantification, respectively the discrimination of the groups in the LDA scatterplot. Feature selection based on the stepwise LDA algorithm as well as selection based on the loadings plot has shown that features both from the temperature cycle and from the bias cycle are equally important for the identification of carbon monoxide, nitrogen dioxide and ammonia. In addition, the presented method allows discrimination of these gases independent of the gas concentration. Hence, the selectivity of the FET is enhanced considerably.

  • 37.
    Bur, Christian
    et al.
    Saarland University, Saarbrücken, Germany.
    Bastuk, Emanuel
    Saarland University, Saarbrücken, Germany.
    Schütze, Andreas
    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.
    Combination of temperature cycled and gate bias cycled operation to enhance the selectivity of MISiC-FET gas sensors2013In: Transducers 2013 & Eurosensors XXVII, IEEE , 2013, 2041-2044 p.Conference paper (Other academic)
    Abstract [en]

    In this paper temperature modulation and gate bias modulation of a gas sensitive field effect transistor are combined in order to increase the selectivity. Data evaluation was performed using multivariate statistics, here by Linear Discriminant Analysis. It was found that both temperature cycling and gate bias cycling are suitable for quantification of different concentrations of carbon monoxide. However, combination of both approaches enhances the quality of the separation. In addition, the presented method allows discrimination of carbon monoxide, nitrogen dioxide and ammonia independent of the gas concentration.

  • 38.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. Saarland University, Lab for Measurement Technology, Germany.
    Bastuk, Manuel
    Saarland University, Lab for Measurement Technology, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Schuetze, Andreas
    Saarland University, Germany.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Discrimination and Quantification of Volatile Organic Compounds in the ppb-Range with Gas Sensitive SiC-FETs Using Multivariate Statistics2015In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 214, 225-233 p.Article in journal (Refereed)
    Abstract [en]

    Gas sensitive field effect transistors based on silicon carbide, SiC-FETs, have been studied for indoor air quality applications. The selectivity of the sensors was increased by temperature cycled operation, TCO, and data evaluation based on multivariate statistics. Discrimination of benzene, naphthalene, and formaldehyde independent of the level of background humidity is possible by using shape describing features as input for Linear Discriminant Analysis, LDA, or Partial Least Squares – Discriminant Analysis, PLS-DA. Leave-one-out cross-validation leads to a correct classification rate of 90 % for LDA, and for PLS-DA a classification rate of 83 % is achieved. Quantification of naphthalene in the relevant concentration range, i.e. 0 ppb to 40 ppb, was performed by Partial Least Squares Regression and a combination of LDA with a second order polynomial fit function. The resolution of the model based on a calibration with three concentrations was approximately 8 ppb at 40 ppb naphthalene for both algorithms.

    Hence, the suggested strategy is suitable for on demand ventilation control in indoor air quality application systems.

  • 39.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Lab for Measurement Technology, Germany.
    Bastuk, Manuel
    Saarland University, Lab for Measurement Technology, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Schuetze, Andreas
    Saarland University, 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.
    Discrimination and Quantification of Volatile Organic Compounds in the ppb-Range with Gas Sensitive SiC-Field Effect Transistors2014Conference paper (Refereed)
    Abstract [en]

    Gas sensitive FETs based on SiC have been studied for the discrimination and quantification of hazardous volatile organiccompounds (VOCs) in the low ppb range. The sensor performance was increased by temperature cycled operation (TCO) anddata evaluation based on multivariate statistics, here Linear Discriminant Analysis (LDA). Discrimination of formaldehyde,naphthalene and benzene with varying concentrations in the ppb range is demonstrated. In addition, it is shown that naphthalenecan be quantified in the relevant concentration range independent of the relative humidity and against a high ethanol background.Hence, gas sensitive SiC-FETs are suitable sensors for determining indoor air quality.

  • 40.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Saarbruecken, Germany.
    Bastuk, Manuel
    Saarland University, Saarbruecken, Germany.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Juuti, Jari
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. University of Oulu, Oulu, Finland.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. University of Oulu, Oulu, Finland.
    Characterization of ash particles with a microheater andgas-sensitive SiC field-effect transistors2014In: Journal of Sensors and Sensor Systems, ISSN 2194-8771, Vol. 3, 305-313 p.Article in journal (Refereed)
    Abstract [en]

    Particle emission from traffic, power plants or, increasingly, stoves and fireplaces poses a serious risk for human health. The harmfulness of the particles depends not only on their size and shape but also on adsorbates. Particle detectors for size and concentration are available on the market; however, determining content and adsorbents is still a challenge. In this work, a measurement setup for the characterization of dust and ash particle content with regard to their adsorbates is presented. For the proof of concept, ammonia-contaminated fly ash samples from a coal-fired power plant equipped with a selective non-catalytic reduction (SNCR) system were used. The fly ash sample was placed on top of a heater substrate situated in a test chamber and heated up to several hundred degrees. A silicon carbide field-effect transistor (SiC-FET) gas sensor was used to detect desorbing species by transporting the headspace above the heater to the gas sensor with a small gas flow. Accumulation of desorbing species in the heater chamber followed by transfer to the gas sensor is also possible. A mass spectrometer was placed downstream of the sensor as a reference. A clear correlation between the SiC-FET response and the ammonia spectra of the mass spectrometer was observed. In addition, different levels of contamination can be distinguished. Thus, with the presented setup, chemical characterization of particles, especially of adsorbates which contribute significantly to the harmfulness of the particles, is possible.

  • 41.
    Bur, Christian
    et al.
    Saarland University, Saarbruecken, Germany.
    Reimann, P.
    Saarland University, Saarbruecken, Germany.
    Andersson, Mike
    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.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Temperature cycled operation of SiC field effect gas sensors: increasing the selectivity for improved sensor systems2011In: AIP. Conf. Proc ISOEN 2011 vol 1362, 2011, 91-92 p.Conference paper (Refereed)
    Abstract [en]

    In order to detect and quantify nitrogen oxides (NOx) in a mixture of typical exhaust gases a diode coupled FET has been investigated using Temperature Cycled Operation. This approach, originally developed for metal oxide gas sensors, is quite new for GasFETs but preliminary studies proved that it is suitable for GasFETs as well. In this paper the basic concept was improved by a temperature cycle tailored to NOx detection. Multivariate statistics have been used to evaluate the sensor data. Measurements have shown that with a piecewise extraction of features, a quantification of NO with additional NO2 is possible in the background of exhaust gases. Thus, the detection of NOx and especially the determination of the concentration can be improved.

  • 42.
    Bur, Christian
    et al.
    Saarland University, Saarbruecken, Germany.
    Reimann, P.
    Saarland University, Saarbruecken, Germany.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Andersson, Mike
    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.
    New method for selectivity enhancement of SiC field effect gas sensors for quantification of NOx2011In: Proc. SPIE 8066, 2011Conference paper (Refereed)
  • 43.
    Bur, Christian
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Reimann, Peter
    University of Saarland, Germany .
    Andersson, Mike
    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.
    Schuetze, Andreas
    University of Saarland, Germany .
    New method for selectivity enhancement of SiC field effect gas sensors for quantification of NO (x)2012In: Microsystem Technologies: Micro- and Nanosystems Information Storage and Processing Systems, ISSN 0946-7076, E-ISSN 1432-1858, Vol. 18, no 7-8, 1015-1025 p.Article in journal (Refereed)
    Abstract [en]

    A silicon carbide based enhancement type metal insulator field effect transistor with porous gate metallization has been investigated as a total NO (x) sensor operated in a temperature cycling mode. This operating mode is quite new for gas sensors based on the field effect but promising results have been reported earlier. Based on static investigations we have developed a suitable T-cycle optimized for NO (x) detection and quantification in a mixture of typical exhaust gases (CO, C2H4, and NH3). Significant features describing the shape of the sensor response have been extracted and evaluated with multivariate statistics (e.g. linear discriminant analysis) allowing quantification of NO (x) . Additional cleaning-cycles every 30 min improve the stability of the sensor further. With this kind of advanced signal processing the influence of sensor drift and cross sensitivity to ambient gases can be reduced effectively. Measurements have proven that different concentrations of NO (x) can be detected even in a changing mixture of other typical exhaust gases under dry and humid conditions. In addition to that, unknown concentrations of NO (x) can be detected based on a small set of training data. It can be concluded that the performance of GasFETs for NO (x) determination can be enhanced considerably with temperature cycling and appropriate signal processing.

  • 44.
    Bur, Christian
    et al.
    University of Saarland.
    Reimann, Peter
    Dillinger Hutte GTS.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Schuetze, Andreas
    University of Saarland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Increasing the Selectivity of Pt-Gate SiC Field Effect Gas Sensors by Dynamic Temperature Modulation2012In: IEEE Sensors Journal, ISSN 1530-437X, E-ISSN 1558-1748, Vol. 12, no 6Article in journal (Refereed)
    Abstract [en]

    Based on a diode coupled silicon carbide field effect transistor (FET) with platinum as catalytic gate material, the influence of dynamic temperature modulation on the selectivity of gas analysis sensors FETs has been investigated. This operating mode, studied intensively for semiconductor gas sensors, has only recently been applied to FETs. A suitable temperature cycle for detection of typical exhaust gases (CO, NO, C3H6, H-2, NH3) was developed and combined with appropriate signal processing. The sensor data were evaluated using multivariate statistics, e.g., linear discriminant analysis. Measurements have proven that typical exhaust gases can be discriminated in backgrounds with 0, 10, and 20% oxygen. Furthermore, we are able to quantify the mentioned gases and to determine unknown concentrations based on training data. Very low levels of relative humidity below a few percent influence the sensor response considerably but for higher levels the cross interference of humidity is negligible. In addition, experiments regarding stability and reproducibility were performed.

  • 45.
    Bur, Christian
    et al.
    Saarland University, Saarbruecken, Germany.
    Schütze, Andreas
    Saarland University, Saarbruecken, Germany.
    Andersson, Mike
    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.
    Hierarcical strategy for quantification of NOx in a varying background of typical exhaust gases2011In: Proc. IEEE Sensors 2011, Limerick, Ireland, October 28-31, IEEE , 2011, 137-140 p.Conference paper (Refereed)
    Abstract [en]

    Silicon carbide based metal insulator field effect transistors (MISiC FET) with a catalytic gate metallization were used in temperature cycled operating mode (TCO) in order to improve the selectivity of the sensor. This approach obtaining multiple data from a single sensor, therefore known as a virtual multisensor, was originally developed for metal oxide sensors but earlier work proved the suitability for MISiC FETs as well. This strategy was now tailored to the quantification of NOx in a mixture of typical exhaust gases (CO, HC, plus NH3). Data was evaluated with multivariate statistics e.g. Linear Discriminant Analysis. In order to suppress the influence of varying background a hierarchical approach was used. Results show that quantification of NOx is possible even in a changing background.

  • 46.
    Chen, Miaoxiang
    et al.
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Perzon, E.
    Materials and Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
    Robinson, Nathaniel D
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Jönsson, Stina
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Andersson, Mike
    Materials and Surface Chemistry, Chalmers University of Technology, Göteborg, Sweden.
    Fahlman, Mats
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Berggren, Magnus
    Linköping University, Department of Science and Technology. Linköping University, The Institute of Technology.
    Low band gap donor–acceptor–donor polymers for infra-red electroluminescence and transistors2004In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 146, no 3, 233-236 p.Article in journal (Refereed)
    Abstract [en]

    We report on transistors and light-emitting diodes using a conjugated polymer consisting of alternated segments of fluorene units and low-band gap donor–acceptor–donor (D–A–D) units. The D–A–D segment includes two electron-donating thiophene rings combined with a thiadiazolo-quinoxaline unit, which is electron withdrawing to its nature. The resulting polymer is conjugated and has a band gap of around 1.27 eV. Here we present the corresponding electro- and photoluminescence spectra, which both peak at approximately 1 μm. Single layer light-emitting diodes demonstrated external quantum efficiencies from 0.03% to 0.05%. The polymer was employed as active material in thin film transistors, a field-effect mobility of 3 × 10−3 cm2/V s and current on/off ratio of 104 were achieved at ambient atmosphere.

  • 47.
    Darmastuti, Zhafira
    et al.
    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.
    Lindqvist, Niclas
    Alstom Power AB, Växjö, Sweden.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    SiC based field effect transistor for H2S detectionManuscript (preprint) (Other academic)
    Abstract [en]

    Pt-gate and Ir-gate SiC-FETs were tested as H2S sensors. Both sensors showed good response towards H2S in dry conditions with oxygen present. Ir-gate sensors showed high sensitivity and low drift, which makes them a suitable candidate for leak detection applications. Further testing was performed with Ir-gate sensors for geothermal applications. This involved humid environments and low oxygen concentrations. The sensitivity of the sensors decreased significantly at these conditions. When propene was added to the gas mixture, crosssensitivity was observed in the sensor signal. Further investigation to reveal the surface chemistry using spectroscopic techniques and modelling is needed to improve the selectivity of Ir-gate sensors in humid conditions and oxygen deficient environments.

  • 48.
    Darmastuti, Zhafira
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry. 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.
    Larsson, Mikael
    Alstom Power, Sweden.
    Lindqvist, Niclas
    Alstom Power, Sweden.
    SiC based field effect transistor for H2S detection2011In: Proc. IEEE Sensors 2011, Limerick, Ireland, October 28-31, IEEE , 2011, 770-773 p.Conference paper (Refereed)
    Abstract [en]

    Experimental characterization and quantum chemical calculations were performed to evaluate the performance of a SiC based Field Effect Transistors with Pt and Ir gates as H2S sensors. The sensors were tested against various concentrations of H2S gas at the operating temperature between 150 and 350 °C. It was observed that Ir was very sensitive and selective to H2S at 350 °C. This phenomenon was studied further by comparing the reaction energy when H2S is exposed to Pt and Ir with density functional theory (DFT) calculations.

  • 49.
    Darmastuti, Zhafira
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Bhattacharyya, P.
    Dept. of Electronics and Telecommunication Engineering, Bengal Engineering and Science University, India.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Kanungo, Jayita
    IC Design & Fabrication Centre, Dept. of Electronics & Telecommunications Engineering, Jadavpur University, Kolkata, India.
    Basu, Sukumar
    IC Design & Fabrication Centre, Dept. of Electronics & Telecommunications Engineering, Jadavpur University, Kolkata, India.
    Käll, Per-Olov
    Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry. Linköping University, The Institute of Technology.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry. 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-FET methanol sensors for process control and leakage detection2013In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 187, no SI, 553-562 p.Article in journal (Refereed)
    Abstract [en]

    Two types of SiC based field effect transistor sensors, with Pt or Ir gate, were tested to detect methanol in the concentration range of 0–1600 ppm for both process control and leak detection applications. The methanol response was investigated both with and without oxygen, since the process control might be considered as oxygen free application, while the sensor is operated in air during leak detection. Pt sensors offered very fast response with appreciably high response magnitude at 200 °C, while Ir sensors showed both higher response and response time up to 300 °C, but this decreased considerably at 350 °C. Cross sensitivity effect in presence of oxygen, hydrogen, propene and water vapor was also investigated. The presence of oxygen improved the response of both sensors, which is favorable for the leak detection application. Hydrogen had a large influence on the methanol response of both sensors, propene had a negligible influence, while water vapor changed direction of the methanol response for the Pt sensor. The detection mechanism and different sensing behavior of Pt and Ir gate sensors were discussed in the light of model reaction mechanisms derived from hybrid density-functional theory quantum-chemical calculations.

  • 50.
    Darmastuti, Zhafira
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Bounechada, Djamela
    Competence Centre for Catalysis / Dept. of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Carlsson, P-A
    Competence Centre for Catalysis / Dept. of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Lindqvist, N.
    Alstom Power AB, Växjö, Sweden.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Skoglundh, Magnus
    Competence Centre for Catalysis / Dept. of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Carlsson, P-A
    Competence Centre for Catalysis /Dept. of Chemical and Biological Engineering, Chalmers University of Technology, Göteborg, Sweden.
    Lloyd Spetz, Anita
    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.
    Detection mechanism studies of SO2 on Pt / SiO2 systemManuscript (preprint) (Other academic)
    Abstract [en]

    Experiment was performed with Pt-gate SiC-FET sensors to study the detection mechanism of the sensors. The sensing measurement showed that oxygen influenced the response quite strongly. The sensor response became larger in the presence of oxygen. Experiment with mass spectroscopy indicated the formation of SO3 during the sensing measurement. Further experiment with DRIFT spectroscopy showed the formation of sulfate species on the oxide surface, accompanied by the disappearance of the silanol groups. An explanatory model was built based on quantum-chemical calculations. The results strengthened the experimental results by showing that it was more energetically favorable for SO2 to oxidize into SO3 before being adsorbed on the oxide surface. It was also observed that the overall adsorption reaction was exothermic, the activation energy for the SO2 oxidation was 48,75 kJ/mol, and the rate limiting step was the desorption of SO3 from the Pt surface.

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