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  • 1.
    Asres, Georgies Alene
    et al.
    Univ Oulu, Finland.
    Jarvinen, Topias
    Univ Oulu, Finland.
    Lorite, Gabriela S.
    Univ Oulu, Finland.
    Mohl, Melinda
    Univ Oulu, Finland.
    Pitkanen, Olli
    Univ Oulu, Finland.
    Dombovari, Aron
    Univ Oulu, Finland.
    Toth, Geza
    VTT Finland, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Univ Oulu, Finland.
    Vajtai, Robert
    Rice Univ, TX 77005 USA.
    Ajayan, Pulickel M.
    Rice Univ, TX 77005 USA.
    Lei, Sidong
    Univ Calif Los Angeles, CA 90095 USA.
    Talapatra, Saikat
    Southern Illinois Univ, IL 62901 USA.
    Kordas, Krisztian
    Univ Oulu, Finland.
    High photoresponse of individual WS2 nanowire-nanoflake hybrid materials2018In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 112, no 23, article id 233103Article in journal (Refereed)
    Abstract [en]

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

  • 2.
    Kilpijarvi, Joni
    et al.
    Univ Oulu, Finland.
    Halonen, Niina
    Univ Oulu, Finland.
    Sobocinski, Maciej
    Univ Oulu, Finland.
    Hassinen, Antti
    Univ Oulu, Finland.
    Senevirathna, Bathiya
    Univ Maryland, MD 20742 USA.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Abshire, Pamela
    Univ Maryland, MD 20742 USA.
    Smela, Elisabeth
    Univ Maryland, MD 20742 USA.
    Kellokumpu, Sakari
    Univ Oulu, Finland.
    Juuti, Jari
    Univ Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    LTCC Packaged Ring Oscillator Based Sensor for Evaluation of Cell Proliferation2018In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 10, article id 3346Article in journal (Refereed)
    Abstract [en]

    A complementary metal-oxide-semiconductor (CMOS) chip biosensor was developed for cell viability monitoring based on an array of capacitance sensors utilizing a ring oscillator. The chip was packaged in a low temperature co-fired ceramic (LTCC) module with a flip chip bonding technique. A microcontroller operates the chip, while the whole measurement system was controlled by PC. The developed biosensor was applied for measurement of the proliferation stage of adherent cells where the sensor response depends on the ratio between healthy, viable and multiplying cells, which adhere onto the chip surface, and necrotic or apoptotic cells, which detach from the chip surface. This change in cellular adhesion caused a change in the effective permittivity in the vicinity of the sensor element, which was sensed as a change in oscillation frequency of the ring oscillator. The sensor was tested with human lung epithelial cells (BEAS-2B) during cell addition, proliferation and migration, and finally detachment induced by trypsin protease treatment. The difference in sensor response with and without cells was measured as a frequency shift in the scale of 1.1 MHz from the base frequency of 57.2 MHz. Moreover, the number of cells in the sensor vicinity was directly proportional to the frequency shift.

  • 3.
    Asres, Georgies Alene
    et al.
    Univ Oulu, Finland.
    Baldovi, Jose J.
    Max Planck Inst Struct and Dynam Matter, Germany; Univ Basque Country, Spain.
    Dombovari, Aron
    Univ Oulu, Finland.
    Jarvinen, Topias
    Univ Oulu, Finland.
    Lorite, Gabriela Simone
    Univ Oulu, Finland.
    Mohl, Melinda
    Univ Oulu, Finland.
    Shchukarev, Andrey
    Umea Univ, Sweden.
    Perez Paz, Alejandro
    Univ Basque Country, Spain; Yachay Tech Univ, Ecuador.
    Xian, Lede
    Max Planck Inst Struct and Dynam Matter, Germany; Univ Basque Country, Spain.
    Mikkola, Jyri-Pekka
    Umea Univ, Sweden; Abo Akad Univ, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. Univ Oulu, Finland.
    Jantunen, Heli
    Univ Oulu, Finland.
    Rubio, Angel
    Max Planck Inst Struct and Dynam Matter, Germany; Univ Basque Country, Spain.
    Kordas, Krisztian
    Univ Oulu, Finland.
    Ultrasensitive H2S gas sensors based on p-type WS2 hybrid materials2018In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 11, no 8, p. 4215-4224Article in journal (Refereed)
    Abstract [en]

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

  • 4.
    Hasegawa, Yuki
    et al.
    Saitama Univ, Japan.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Ethylene Gas Sensor for Evaluating Postharvest Ripening of Fruit2017In: 2017 IEEE 6TH GLOBAL CONFERENCE ON CONSUMER ELECTRONICS (GCCE), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    It is widely known that ethylene treatment is an effective method for postharvest handling of fruit. In this study, we employed a field effect transistor based on silicon carbide (SiC-FET) gas sensor for detecting ethylene produced from fruits. The characteristics of the sensor was evaluated regarding several parameters. The selectivity and sensitivity of SiC-FET sensors can be controlled toward a few target gases by changing the operating temperature, gate material and material structure. We studied an iridium and a platinum gated SiC-FET sensors and characterized the sensing of these for different ethylene concentrations as the target gas at different operating temperatures. The results showed that the iridium gated SiC-FET sensor has high sensitivity to ethylene, and the highest response is achieved at 200 degrees C.

  • 5.
    Penza, Michele
    et al.
    ENEA, Italy.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Romano-Rodriguez, Albert
    University of Barcelona, Spain.
    Meyyappan, Meyya
    NASA, CA 94035 USA.
    Functional materials for environmental sensors and energy systems2017In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 8, p. 2015-2016Article in journal (Other academic)
    Abstract [en]

    n/a

  • 6.
    Erdtman, Edvin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. 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.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Simulations of the thermodynamics and kinetics of NH3 at the RuO2 (110) surface2017In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 656, p. 9p. 77-85Article in journal (Refereed)
    Abstract [en]

    Ruthenium(IV)oxide (RuO2) is a material used for various purposes. It acts as a catalytic agent in several reactions, for example oxidation of carbon monoxide. Furthermore, it is used as gate material in gas sensors. In this work theoretical and computational studies were made on adsorbed molecules on RuO2 (110) surface, in order to follow the chemistry on the molecular level. Density functional theory calculations of the reactions on the surface have been performed. The calculated reaction and activation energies have been used as input for thermodynamic and kinetics calculations. A surface phase diagram was calculated, presenting the equilibrium composition of the surface at different temperature and gas compositions. The kinetics results are in line with the experimental studies of gas sensors, where water has been produced on the surface, and hydrogen is found at the surface which is responsible for the sensor response.

  • 7.
    Fashandi, Hossein
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Synthesis of Ti3AuC2, Ti3Au2C2 and Ti3IrC2 by noble metal substitution reaction in Ti3SiC2 for high-temperature-stable Ohmic contacts to SiC2017In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 16, no 8, p. 814-818Article in journal (Refereed)
    Abstract [en]

    The large class of layered ceramics encompasses both van der Waals (vdW) and non-vdW solids. While intercalation of noble metals in vdW solids is known, formation of compounds by incorporation of noble-metal layers in non-vdW layered solids is largely unexplored. Here, we show formation of Ti3AuC2 and Ti3Au2C2 phases with up to 31% lattice swelling by a substitutional solid-state reaction of Au into Ti3SiC2 single-crystal thin films with simultaneous out-diffusion of Si. Ti3IrC2 is subsequently produced by a substitution reaction of Ir for Au in Ti3Au2C2. These phases form Ohmic electrical contacts to SiC and remain stable after 1,000 h of ageing at 600 degrees C in air. The present results, by combined analytical electron microscopy and ab initio calculations, open avenues for processing of noble-metal-containing layered ceramics that have not been synthesized from elemental sources, along with tunable properties such as stable electrical contacts for high-temperature power electronics or gas sensors.

  • 8.
    Fashandi, Hossein
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lai, Chung-Chuan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Dahlqvist, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. 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.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ti2Au2C and Ti3Au2C2 formed by solid state reaction of gold with Ti2AlC and Ti3AlC22017In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 69, p. 9554-9557Article in journal (Refereed)
    Abstract [en]

    Incorporation of layers of noble metals in non-van der Waals layered materials may be used to form novel layered compounds. Recently, we demonstrated a high-temperature-induced exchange process of Au with Si in the layered phase Ti3SiC2, resulting in the formation of Ti3AuC2 and Ti3Au2C2. Here, we generalize this technique showing that Au/Ti2AlC and Au/Ti3AlC2 undergo an exchange reaction at 650 [degree]C to form Ti2Au2C and Ti3Au2C2 and determine their structures by electron microscopy, X-ray diffraction, and ab initio calculations. These results imply that noble-metal-containing layered phases should be possible to synthesize in many systems. The metal to be introduced should be inert to the transition-metal carbide layers, and exhibit negative heat of mixing with the initial A element in a liquid phase or two-phase liquid/solid region at the annealing temperature.

  • 9.
    Alene Asres, Georgies
    et al.
    University of Oulu, Finland.
    Dombovari, Aron
    University of Oulu, Finland.
    Sipola, Teemu
    University of Oulu, Finland.
    Puskas, Robert
    University of Szeged, Hungary.
    Kukovecz, Akos
    University of Szeged, Hungary; MTA SZTE Lendulet Porous Nanocomposites Research Grp, Hungary.
    Konya, Zoltan
    University of Szeged, Hungary; MTA SZTE React Kinet and Surface Chemistry Research Grp, Hungary.
    Popov, Alexey
    University of Oulu, Finland.
    Lin, Jhih-Fong
    University of Oulu, Finland.
    Lorite, Gabriela S.
    University of Oulu, Finland.
    Mohl, Melinda
    University of Oulu, Finland.
    Toth, Geza
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Kordas, Krisztian
    University of Oulu, Finland.
    A novel WS2 nanowire-nanoflake hybrid material synthesized from WO3 nanowires in sulfur vapor2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, no 25610Article in journal (Refereed)
    Abstract [en]

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

  • 10.
    Fashandi, Hossein
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Soldemo, Markus
    KTH Royal Institute Technology, Sweden.
    Weissenrieder, Jonas
    KTH Royal Institute Technology, Sweden.
    Gothelid, Mats
    KTH Royal Institute Technology, Sweden.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Applicability of MOS structures in monitoring catalytic properties, as exemplified for monolayer-iron-oxide-coated porous platinum films2016In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 344, p. 583-590Article in journal (Refereed)
    Abstract [en]

    Metal Oxide Semiconductor (MOS) capacitor devices comprised of monolayer iron oxide-coated as well as non-coated polycrystalline Pt deposited on oxidized silicon carbide substrates have been fabricated and their usefulness as realistic model systems in catalyst studies development was evaluated. The CO oxidation characteristics of both iron oxide- and non-coated Pt catalysts were investigated using mass spectrometry, monitoring the carbon dioxide production rate for different combinations of carbon monoxide (CO) and oxygen concentrations at various temperatures. Additionally, the output capacitance of the MOS model catalysts was recorded for each individual CO oxidation activity. A low-temperature shift in CO oxidation characteristics for the monolayer-coated compared to the non-coated Pt catalysts was observed, similar to that previously reported for monolayer iron oxide grown on single-crystalline Pt substrates. A strong correlation between the output capacitance of the MOS structures and the CO oxidation characteristics was found for both monolayer- and non-coated model catalysts. Furthermore, the devices exhibit retained MOS electrical output and CO oxidation characteristics as well as an unaffected catalyst surface composition, as confirmed by photoelectron spectroscopy, even after 200 h of continuous model catalyst operation. In addition to the implications on practical applicability of monolayer iron oxide coating on widely used polycrystalline Pt films in real-world catalysts and sensors, the findings also point to new possibilities regarding the use of MOS model systems for in situ characterization, high throughput screening, and tailoring of e.g. catalyst- and fuel-cell-electrode materials for specific applications. (C) 2016 Elsevier Inc. All rights reserved.

  • 11.
    Bastuck, Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. University of Saarland, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Schuetze, A.
    University of Saarland, Germany.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Characterizing the Influence of Gate Bias on Electrical and Catalytical Properties of a Porous Platinum Gate on Field Effect Gas Sensors2016In: 2016 IEEE SENSORS, IEEE , 2016Conference paper (Refereed)
    Abstract [en]

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

  • 12.
    Puglisi, Donatella
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science.
    Huotari, Joni
    University of Oulu, Finland.
    Bastuck, Manuel
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Saarland University, Saarbruecken, Germany.
    Bur, Christian
    Linköping University, Department of Physics, Chemistry and Biology. Saarland University, Lab for Measurement Technology, Germany.
    Lappalainen, Jyrki
    University of Oulu, Finland.
    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.
    Exploring the gas sensing performance of catalytic metal/ metal oxide 4H-SiC field effect transistors2016In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 858, p. 997-1000Article in journal (Refereed)
    Abstract [en]

    Gas sensitive metal/metal-oxide field effect transistors based on silicon carbide were used to study the sensor response to benzene (C6H6) at the low parts per billion (ppb) concentration range. A combination of iridium and tungsten trioxide was used to develop the sensing layer. Highsensitivity to 10 ppb C6H6 was demonstrated during several repeated measurements at a constant temperature from 180 to 300 °C. The sensor performance was studied also as a function of the electrical operating point of the device, i.e., linear, onset of saturation, and saturation mode. Measurements performed in saturation mode gave a sensor response up to 52 % higher than those performed in linear mode.

  • 13.
    Bastuck, Manuel
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. University of Saarland, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Huotari, J.
    University of Oulu, Finland.
    Sauerwald, T.
    University of Saarland, Germany.
    Lappalainen, J.
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Schuetze, A.
    University of Saarland, Germany.
    Exploring the selectivity of WO3 with iridium catalyst in an ethanol/naphthalene mixture using multivariate statistics2016In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 618, p. 263-270Article in journal (Refereed)
    Abstract [en]

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

  • 14.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Fashandi, Hossein
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering.
    Huotari, J.
    University of Oulu, Finland.
    Puustinen, J.
    University of Oulu, Finland.
    Lappalainen, J.
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Sensor and Actuator Systems. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Field Effect Based Gas Sensors, from Basic Mechanisms to the Latest Commercial Device Designs2016In: SENSORS AND ELECTRONIC INSTRUMENTATION ADVANCES (SEIA), INT FREQUENCY SENSOR ASSOC-IFSA , 2016, p. 19-21Conference paper (Refereed)
    Abstract [en]

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

  • 15.
    Sobocinski, Maciej
    et al.
    University of Oulu, Finland.
    Myllymäki, Sami
    University of Oulu, Finland.
    Nello, Mikko
    University of Oulu, Finland.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Juuti, Jari
    University of Oulu, Finland.
    Kilpijärvi, Joni
    University of Oulu, Finland.
    Halonen, Niina
    University of Oulu, Finland.
    Jantunen, Heli
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Laser shaped thick-film IDE for nanoparticle detection at high frequencies2016In: Proceedings EMRS 2016, 2016Conference paper (Refereed)
  • 16.
    Halonen, Niina
    et al.
    University of Oulu, Finland.
    Kilpijaervi, Joni
    University of Oulu, Finland.
    Sobocinski, Maciej
    University of Oulu, Finland.
    Datta-Chaudhuri, Timir
    University of Maryland, MD 20742 USA.
    Hassinen, Antti
    University of Oulu, Finland.
    Prakash, Someshekar B.
    University of Maryland, MD 20742 USA; Intel Corp, OR 97124 USA.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Abshire, Pamela
    University of Maryland, MD 20742 USA.
    Kellokumpu, Sakari
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Low temperature co-fired ceramic packaging of CMOS capacitive sensor chip towards cell viability monitoring2016In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 7, p. 1871-1877Article in journal (Refereed)
    Abstract [en]

    Cell viability monitoring is an important part of biosafety evaluation for the detection of toxic effects on cells caused by nanomaterials, preferably by label-free, noninvasive, fast, and cost effective methods. These requirements can be met by monitoring cell viability with a capacitance-sensing integrated circuit (IC) microchip. The capacitance provides a measurement of the surface attachment of adherent cells as an indication of their health status. However, the moist, warm, and corrosive biological environment requires reliable packaging of the sensor chip. In this work, a second generation of low temperature co-fired ceramic (LTCC) technology was combined with flip-chip bonding to provide a durable package compatible with cell culture. The LTCC-packaged sensor chip was integrated with a printed circuit board, data acquisition device, and measurement-controlling software. The packaged sensor chip functioned well in the presence of cell medium and cells, with output voltages depending on the medium above the capacitors. Moreover, the manufacturing of microfluidic channels in the LTCC package was demonstrated.

  • 17.
    Kilpijärvi, Joni
    et al.
    University of Oulu, Finland.
    Sobocinski, Maciej
    University of Oulu, Finland.
    Halonen, Niina
    University of Oulu, Finland.
    Hassinen, Antti
    University of Oulu, Finland.
    Prakash, Someshekar Bangalore
    University of Maryland, Baltimore, USA.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Abshire, Pamela
    University of Maryland, Baltimore, USA.
    Smela, Elisabeth
    University of Maryland, Baltimore, USA.
    Kellokumpu, Sakari
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    LTCC packaging for lab-on-CMOS applied in cell viability monitoring2016In: Proceedings EMRS 2016, 2016Conference paper (Refereed)
  • 18.
    Eriksson, Jens
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Strandqvist, Carl
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. Graphensic AB Linköping, Sweden.
    Gunnarsson, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Ekeroth, Sebastian
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Ivanov, Ivan Gueorguiev
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Uvdal, Kajsa
    Linköping University, Department of Physics, Chemistry and Biology, Molecular Surface Physics and Nano Science. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering. Graphensic AB Linköping, Sweden.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Modified Epitaxial Graphene on SiC for Extremely Sensitive andSelective Gas Sensors2016In: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 858, p. 1145-1148Article in journal (Refereed)
    Abstract [en]

    Two-dimensional materials offer a unique platform for sensing where extremely high sensitivity is a priority, since even minimal chemical interaction causes noticeable changes inelectrical conductivity, which can be used for the sensor readout. However, the sensitivity has to becomplemented with selectivity, and, for many applications, improved response- and recovery times are needed. This has been addressed, for example, by combining graphene (for sensitivity) with metal/oxides (for selectivity) nanoparticles (NP). On the other hand, functionalization or modification of the graphene often results in poor reproducibility. In this study, we investigate thegas sensing performance of epitaxial graphene on SiC (EG/SiC) decorated with nanostructured metallic layers as well as metal-oxide nanoparticles deposited using scalable thin-film depositiontechniques, like hollow-cathode pulsed plasma sputtering. Under the right modification conditions the electronic properties of the surface remain those of graphene, while the surface chemistry can betuned to improve sensitivity, selectivity and speed of response to several gases relevant for airquality monitoring and control, such as nitrogen dioxide, benzene, and formaldehyde.

  • 19.
    Shtepliuk, Ivan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Iakimov, Tihomir
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Monolayer graphene/SiC Schottky barrier diodes with improved barrier height uniformity as a sensing platform for the detection of heavy metals2016In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 7, p. 1800-1814Article in journal (Refereed)
    Abstract [en]

    A vertical diode structure comprising homogeneous monolayer epitaxial graphene on silicon carbide is fabricated by thermal decomposition of a Si-face 4H-SiC wafer in argon atmosphere. Current-voltage characteristics of the graphene/SiC Schottky junction were analyzed by applying the thermionic-emission theory. Extracted values of the Schottky barrier height and the ideality factor are found to be 0.4879 +/- 0.013 eV and 1.01803 +/- 0.0049, respectively. Deviations of these parameters from average values are smaller than those of previously observed literature data, thereby implying uniformity of the Schottky barrier height over the whole diode area, a stable rectifying behaviour and a good quality of ohmic palladium-graphene contacts. Keeping in mind the strong sensitivity of graphene to analytes we propose the possibility to use the graphene/SiC Schottky diode as a sensing platform for the recognition of toxic heavy metals. Using density functional theory (DFT) calculations we gain insight into the nature of the interaction of cadmium, mercury and lead with graphene as well as estimate the work function and the Schottky barrier height of the graphene/SiC structure before and after applying heavy metals to the sensing material. A shift of the I-V characteristics of the graphene/SiC-based sensor has been proposed as an indicator of presence of the heavy metals. Since the calculations suggested the strongest charge transfer between Pb and graphene, the proposed sensing platform was characterized by good selectivity towards lead atoms and slight interferences from cadmium and mercury. The dependence of the sensitivity parameters on the concentration of Cd, Hg and Pb is studied and discussed.

  • 20.
    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)
  • 21.
    Huotari, J.
    et al.
    University of Oulu, Finland.
    Cao, W.
    University of Oulu, Finland.
    Niu, Y.
    Lund University, Sweden.
    Lappalainen, J.
    University of Oulu, Finland.
    Puustinen, J.
    University of Oulu, Finland.
    Pankratov, V.
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Huttula, M.
    University of Oulu, Finland.
    Separation of valence states in thin films with mixed V2O5 and V7O16 phases2016In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 211, p. 47-54Article in journal (Refereed)
    Abstract [en]

    Among the other applications, vanadium oxide thin films are considered to be excellent candidates for gas sensing. To understand the origins of the sensing capability, we carried out X-ray photoelectron and X-ray absorption spectroscopy measurements to determinate the surface valence states of thin films with mixed V7O16 and V2O5 compounds. Thin films were fabricated by pulsed laser deposition, and the crystal structure and symmetry of the deposited films was studied using grazing incidence X-ray diffraction and Raman spectroscopy. These results together with X-ray photoelectron and absorption spectra showed that the thin-film crystal structures varied between orthorhombic V2O5 phase and another phase of triclinic V7O16. X-ray photoelectron spectroscopy was used to quantitatively confirm the high amount of V4+ ions on surfaces of the films, especially of films with V7O16 phase present. This result was confirmed in the quantitative analysis of the V2p near -edge X-ray absorption spectra. Through the observed electronic structures, it was found that in addition to unique crystal structure and morphology, the enhanced gas sensitivity of these layers is attributed to the increase in the amount of surface oxygen vacancies. (C) 2016 Elsevier B.V. All rights reserved.,

  • 22.
    Sobocinski, Maciej
    et al.
    University of Oulu, Finland.
    Bilby, David
    Ford Motor Co, USA.
    Kubinski, David
    Ford Motor Co, USA.
    Visser, Jaco
    Ford Motor Co, USA.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Juuti, Jari
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Jantunen, Heli
    University of Oulu, Finland.
    SiC MOSFET soot sensor in a co-fired LTCC package2016In: PROCEEDINGS OF THE 30TH ANNIVERSARY EUROSENSORS CONFERENCE - EUROSENSORS 2016, ELSEVIER SCIENCE BV , 2016, Vol. 168, p. 27-30Conference paper (Refereed)
    Abstract [en]

    A novel method for soot detection based on SiC MOSFET devices with a dual suspended/floating gate configuration in a co-fired LTCC package has been investigated. Response to different concentrations of soot was measured through the application of an electric field between the two gate electrodes to attract charged soot onto the sensor surface. Results are promising with application areas from automotive and transportation to air pollution control. (C) 2016 The Authors. Published by Elsevier Ltd.

  • 23.
    Eriksson, Jens
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    SiC-2D-material-hybrids as a Platform for Extremely Sensitive and Selective Gas Sensors2016In: Proceedings EMRS 2016, 2016Conference paper (Refereed)
  • 24.
    Andersson, Mike
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland, SenSiC AB, Kista, Sweden .
    Bastuck, Manuel
    Saarland University, Lab for Measurement Technology, Germany.
    Huotari, Joni
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Lappalainen, Jyrki
    University of Oulu, Finland.
    Schuetze, Andreas
    Saarland University, Germany.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    SiC-FET sensors for selective and quantitative detection of VOCs down to ppb level2016In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 168, p. 216-220Article in journal (Refereed)
    Abstract [en]

    With the increased interest in development of cheap, simple means for indoor air quality monitoring, and specifically in relation to certain well-known pollutant substances with adverse health effects even at very low concentrations, such as different Volatile Organic Compounds (VOCs), this contribution aims at providing an overview of the development status of the silicon carbide field effect transistor (SiC FET) based sensor platform for ppb level detection of VOCs. Optimizing the transducer design, the gas-sensitive material(s) composition, structure and processing, its mode of operation - applying temperature cycled operation in conjunction with multivariate data evaluation - and long-term performance it has been possible to demonstrate promising resultsregarding the sensor technology’s ability to achieve both single-digit ppb sensitivity towards e.g. naphthalene as well as selective detection of individual substances in a mixture of different VOCs.

  • 25.
    Huotari, J.
    et al.
    University of Oulu, Finland.
    Lappalainen, J.
    University of Oulu, Finland.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Bjorklund, Robert
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Heinonen, E.
    Centre Microscopy and Nanotechnol, Finland.
    Miinalainen, I.
    University of Oulu, Finland.
    Puustinen, J.
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Synthesis of nanostructured solid-state phases of V7O16 and V2O5 compounds for ppb-level detection of ammonia2016In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 675, p. 433-440Article in journal (Refereed)
    Abstract [en]

    Solid state phase of V7O16 with separate V2O5 phase were fabricated by pulsed laser deposition. The crystal structure and symmetry of the deposited films were studied with X-ray diffraction and Raman spectroscopy, respectively. Rietveld analysis was performed to the X-ray diffraction measurement results. The surface potentials and morphologies of the films were studied with atomic force microscopy, and microstructure of the thin films was analysed by transmission electron microscopy. Raman spectroscopy and Rietveld refinement results confirmed that the thin-film crystal structures varied between orthorombic V2O5 phase and another phase, triclinic V2016, previously found only in the walls of vanadium oxide nanotubes (VOx, -NT), bound together with organic amine. We have earlier presented the first results of stable and pure metal -oxide solid-state phase of V2016 manufactured from ceramic V205 target. Here we show more detailed study of these structures. The microstructure studies showed a variation on the porosity of the films according to crystal structures and also some fibre -like nanostructures were found in the films. The surface morphology depended strongly on the crystal structure and the surface potential studies showed 50 meV difference in the work function values between the phases. Compounds were found to be extremely sensitive towards ammonia, NH3, down to 40 ppb concentrations, and have shown to have the stability and selectivity to control the Selective Catalytic Reduction process, where nitrogen oxides are reduced by ammonia in, e.g. diesel exhausts.

  • 26.
    Huotari, Joni
    et al.
    University of Oulu, Finland.
    Lappalainen, Jyrki
    University of Oulu, Finland.
    Puustinen, Jarkko
    University of Oulu.
    Baur, Tobias
    Saarland University, Germany.
    Alepee, Christine
    SGX Sensortech SA, Switzerland.
    Haapalainen, Tomi
    University of Oulu, Finland.
    Komulainen, Samuli
    University of Oulu, Finland.
    Pylvänäinen, Juho
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Agglomerates, and Nanotrees for Chemical Sensors2015In: Proceeding Eurosensors 2015, 2015, p. 1265-1268Conference paper (Refereed)
  • 27.
    Puglisi, Donatella
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Bur, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University, Lab for Measurement Technology, Germany.
    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.
    Catalytic metal-gate field effect transistors based on SiC for indoor air quality control2015In: Journal of Sensors and Sensor Systems, ISSN 2194-8771, Vol. 4, p. 1-8Article in journal (Refereed)
    Abstract [en]

    High-temperature iridium-gated field effect transistors based on silicon carbide have been used for sensitive detection of specific volatile organic compounds (VOCs) in concentrations of health concern, for indoorair quality monitoring and control. Formaldehyde, naphthalene, and benzene were studied as hazardous VOCs at parts per billion (ppb) down to sub-ppb levels. The sensor performance and characteristics were investigated at a constant temperature of 330° C and at different levels of relative humidity up to 60 %, showing good stability and repeatability of the sensor response, and excellent detection limits in the sub-ppb range.

  • 28.
    Fashandi, Hossein
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Ivády, Viktor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Katsnelson, Mikhail I.
    Radboud University of Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands / Dept. of Theoretical Physics and Applied Mathematics, Ural Federal University, Russia.
    Abrikosov, Igor A.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology. School of Information and Communication Technology, KTH, Stockholm, Sweden.
    Dirac points with giant spin-orbit splitting in the electronic structure of two-dimensional transition-metal carbides2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 15Article in journal (Refereed)
    Abstract [en]

    We investigated the structural and electrical properties of 2D MXene sheets by means of firstprinciples density functional theory (DFT) calculations. To describe the Kohn-Sham states, plane wave basis set and projector augmented wave method (PAW) were used as implemented in the Vienna ab initio Simulation Package (VASP). We applied PBE parameterization of the generalized gradient approximation of the exchange and correlation energy functional to account for many-body effects of the interacting electron system. Convergent sampling of the Brillouin-zone was achieved by a Γ-centered 15×15×1 grid. In order to model a single sheet of MXene we ensured at least 30 Å vacuum between the periodically repeated sheets. For the structural optimization 1×10−3 eV/Å force criteria was used. The relativistic spin-orbit coupling effects were also included in our simulations regarding band structure and density of states.

  • 29.
    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, p. 225-233Article 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.

  • 30.
    Afzal, Adeel
    et al.
    University of Bari Aldo Moro, Italy; King Fahd University of Petr and Minerals, Saudi Arabia; University of Hafr Al Batin, Saudi Arabia.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Di Franco, Cinzia
    CNR IFN UOS Bari, Italy.
    Ditaranto, Nicoletta
    University of Bari Aldo Moro, Italy.
    Cioffi, Nicola
    University of Bari Aldo Moro, Italy; University of Bari Aldo Moro, Italy.
    Scamarcio, Gaetano
    CNR IFN UOS Bari, Italy; University of Bari Aldo Moro, Italy.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Torsi, Luisa
    University of Bari Aldo Moro, Italy; University of Bari Aldo Moro, Italy.
    Electrochemical deposition of gold on indium zirconate (InZrOx with In/Zr atomic ratio 1.0) for high temperature automobile exhaust gas sensors2015In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, Vol. 19, no 9, p. 2859-2868Article in journal (Refereed)
    Abstract [en]

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

  • 31.
    Puglisi, Donatella
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Huotari, Joni
    University of Oulu, Finland.
    Bastuk, Manuel
    Saarland University, Saarbruecken, 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.
    Exploring the gas sensing performance of catalytic metal/ metal oxide 4H-SiC field effect transistors2015In: ICSCRM 2015, 2015Conference paper (Refereed)
  • 32.
    Darmastuti, Zhafira
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Bur, Christian
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology. Saarland University.
    Lindqvist, Niclas
    Alstom Power AB, Växjö, Sweden.
    Anderson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Schutza, 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.
    Hierarchical methods to improve the performance of the SiC - FET as SO2 sensors in flue gas desulphurization system2015In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 206, p. 609-616Article in journal (Refereed)
    Abstract [en]

    Experiments were performed both in the laboratory and a desulfurization pilot unit in order to improve the SiC-FET sensor performance using two-step data evaluation. In both cases, a porous Pt-gate enhancement type SiC-FET was utilized in a temperature cycled operation (TCO). Liner Discriminant Analysis (LDA) was chosen as the method for multivariate data analysis. Hierarchical methods with two-step LDA worked quite well in the laboratory tests with SO2 concentrations varied from 25-200 ppm. The same data evaluation was also applied to tests in the desulfurization pilot unit, with higher gas flow and a larger SO2 concentration range (up to 5000 ppm). The results from the SO2 quantification showed a significantly improved fit to corresponding reference instrument (FTIR) values.

  • 33.
    Khajavizadeh, Lida
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Investigations of 600oC SiC MISFET gas sensor operation2015Conference paper (Refereed)
  • 34.
    Halonen, Niina
    et al.
    University of Oulu, Finland.
    Kilpijärvi, Joni
    University of Oulu, Finland.
    Sobocinski, Maciej
    University of Oulu, Finland.
    Datta-Chaudhuri, Timir
    University of Maryland, Baltimore, USA.
    Hassinen, Antti
    University of Oulu, Finland.
    Prakash, S. B.
    University of Maryland, Baltimore, USA.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Abshire, Pamela
    University of Maryland, Baltimore, USA.
    Smela, Elisabeth
    University of Maryland, Baltimore, USA.
    Kellokumpu, Sakari
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Low temperature co-fired ceramic package for lab-on-a­chip applied in cell viability monitoring2015In: Proceedings Eurosensors 2015, 2015, p. 1187-1190Conference paper (Refereed)
  • 35.
    Halonen, Niina
    et al.
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Kilpijärvi, Joni
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Sobocinski, Maciej
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Datta-Chaudhuri, Timir
    Laboratory for MicroTechnologies, Department of Mechanical Engineering and the Institute for Systems Research ,University of Maryland, Baltimore, USA.
    Hassinen, Antti
    Division of Cell Biology, Department of Biochemistry, University of Oulu, Finland.
    Prakash, S. B.
    Integrated Biomorphic Information System Laboratory, University of Maryland, Baltimore, USA.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Abshire, Pamela
    Integrated Biomorphic Information System Laboratory, University of Maryland, Baltimore, USA.
    Smela, Elisabeth
    Laboratory for MicroTechnologies, Department of Mechanical Engineering and the Institute for Systems Research, University of Maryland, Baltimore, USA.
    Kellokumpu, Sakari
    Division of Cell Biology, Department of Biochemistry, University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. Univ Oulu, Oulu, Finland.
    Low temperature co-fired ceramic package for lab-on-CMOS applied in cell viability monitoring2015In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 120, p. 1079-1082Article in journal (Refereed)
    Abstract [en]

    Lab-on-CMOS chips (LOCMOS) are sophisticated miniaturized analysis tools based on integrated circuit (IC) microchips performing various laboratory functions. We have developed a low temperature co-fired ceramic (LTCC) package for a LOCMOS application regarding cytotoxicity assessment of nanomaterials. The LTCC packaged capacitance sensor chip is designed for long-term cell viability monitoring during nanoparticle exposure. The introduced LTCC package utilizes the flip chip bonding technique, and it is biocompatible as well as able to withstand the environmental conditions required to maintain mammalian cell culture directly on the surface of a complementary metal oxide semiconductor (CMOS) integrated circuit.

  • 36.
    Lloyd Spetz, Anita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Sobocinski, Maciej
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Halonen, Niina
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Juuti, Jari
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Jantunen, Heli
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    LTCC, new packaging approach for toxic gas and particle detection2015In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 120, p. 484-487Article in journal (Refereed)
    Abstract [en]

    Packaging of chemical sensors is still an area, which is not much explored. Low temperature co-fired ceramic, LTCC, packaging offers large advantages in terms of 3D design, integration of advanced functionality and fast processing. SiC based FET gas sensors are possible to integrate directly in the LTCC co-firing process at 850 °C, whereby both high temperature and other advanced applications like ultra-low detection of toxic gases are greatly improved. The LTCC packaging is also used for development of particle detectors as well as packaging for an electrical method to detect toxic effect on cells by particles.

  • 37.
    Lloyd Spetz, Anita
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Sobocinski, Maciej
    University of Oulu, Finland.
    Halonen, Niina
    University of Oulu, Finland.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Juuti, Jari
    University of Oulu, Finland.
    Jantunen, Heli
    University of Oulu, Finland.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    LTCC, new packaging approach for toxic gas and particle detectors2015In: Proceedings Eurosensors 2015, 2015, p. 592-595Conference paper (Refereed)
  • 38.
    Fashandi, Hossein
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Soldemo, M.
    KTH Royal Institute of Technology, Material Physics, Kista, Sweden.
    Weissenrieder, J.
    KTH Royal Institute of Technology, Material Physics, Kista, Sweden.
    Götelid, M.
    KTH Royal Institute of Technology, Material Physics, Kista, Sweden.
    Eriksson, Johan
    Linköping University, Department of Physics, Chemistry and Biology, Surface and Semiconductor Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    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.
    Monolayer iron oxide grown on porous platinum sensing layers of carbon monoxide sensors2015Manuscript (preprint) (Other academic)
    Abstract [en]

    Mono-layer iron oxide has been deposited through e-beam evaporation on a silica supported poly-crystalline platinum (Pt) model catalyst and its CO oxidation characteristics obtained from mass spectrometry measurements under various CO and O2 concentrations (ranging from 100 to 900 ppm and 3 to 7 %, respectively) as well as at different temperatures (ranging from 130 to 220 °C) and compared to the CO oxidation on corresponding non-coated Pt samples. Fabricating the model system as a Metal Oxide Semiconductor (MOS) structure from 4H-SiC with a top layer of SiO2 (as the support material) and a thin, discontinuous polycrystalline Pt film as the metal (the active catalyst material) also provided the possibility to investigate whether changes in catalyst surface conditions could be electronically monitored through the changes in capacitance they induce across the MOS structure.

    A low-temperature shift in the activity to CO oxidation for the iron oxide modified compared to bare Pt catalysts similar to what has previously been reported on single-crystalline Pt was found also for the near-realistic MOS model catalyst. This low-temperature shift was furthermore reflected in the electrical measurements, strongly indicating a correlation between the MOS capacitance and the CO oxidation characteristics, both in the case of iron oxide coated and non-coated Pt samples. By monitoring the MOS capacitance during more than 200 hours of continuous operation and analyzing the iron oxide coated samples by photo electron spectroscopy it could also be concluded that the iron oxide coated model catalyst seemingly retains its CO oxidation characteristics and chemical/compositional integrity over time. These findings might not only point to the applicability of iron oxide modified Pt in practical applications but may also open up new possibilities regarding the utilization of MOS model systems in studying and understanding as well as tailor CO oxidation (and other) catalysts and/or gas sensors for specific applications.

  • 39.
    Möller, Peter
    et al.
    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.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Puustinen, Jarkko
    University of Oulu.
    Lappalainen, Jyrki
    University of Oulu, Finland.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    NOx sensing with SiC field effect transistors2015Conference paper (Refereed)
  • 40.
    Sobocinski, Maciej
    et al.
    University of Oulu, Finland.
    Khajavizadeh, Lida
    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.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Juuti, Jari
    University of Oulu, Finland.
    Jantunen, Heli
    University of Oulu, Finland.
    Performance of LTCC embedded gas sensors2015In: Proceedings Eurosensors 2015, 2015, p. 361-364Conference paper (Refereed)
  • 41.
    Sobocinski, Maciej
    et al.
    Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Khajavizadeh, Lida
    Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Juuti, Jari
    Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Jantunen, Heli
    Microelectronics and Material Physics Laboratories University of Oulu, Finland.
    Performance of LTCC embedded SiC gas sensors2015In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 120, p. 253-256Article in journal (Refereed)
    Abstract [en]

    A novel approach to encapsulation/packaging of SiC field effect transistor gas sensors for high temperature applications, such as exhaust and fuel gas emissions monitoring, based on direct co-firing of sensor devices and Low-Temperature Co-fired Ceramics (LTCC) has been investigated. Structural (SEM, EDX, XPS), electrical (I/V, C/V) as well as gas sensing characterization of packaged devices has shown that the “one-step” packaging process forms a hermetic package with retained transducer functionality and gas sensing characteristics without the need for any separate die attachment, (wire) bonding, and/or sealing of the package. Long-term stability testing at elevated temperatures of packaged devices has also shown promising results.

  • 42.
    Huotari, J.
    et al.
    University of Oulu, Finland.
    Bjorklund, Robert
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lappalainen, J.
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. University of Oulu, Finland.
    Pulsed Laser Deposited Nanostructured Vanadium Oxide Thin Films Characterized as Ammonia Sensors2015In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 217, p. 22-29Article in journal (Refereed)
    Abstract [en]

    Vanadium oxide thin films were fabricated by pulsed laser deposition. The microstructure and crystal symmetry of the deposited films were studied with X-ray diffraction, scanning electron microscopy (SEM), and Raman spectroscopy, respectively. The films surface morphology was examined by atomic force microscopy. Raman spectroscopy and XRD results showed that the thin film phase-structure was composed of pure orthorhombic V2O5 phase, or they had a mixed phase structure of orthorhombic V2O5 and triclinic V7O16. Surface morphology of the films consisted of nanosized particles, although in pure V2O5 films some bigger agglomerates and flakes were also seen. The conductivity based gas sensing measurements showed a clear response already at ppb-levels of NH3 and strong selectivity to ammonia was found when compared to NO and CO gases. Also, the films showed promising gas sensing behavior in cross-sensitivity measurements between NO and NH3, being able to sense ammonia even in the presence of NO. This is an important property when considering possible sensing applications to control Selective Catalytic Reduction processes, e.g. in diesel engine exhausts, where introduced ammonia, or urea, transforms nitrogen oxide gases in a catalytic converter to nitrogen and water. (C) 2015 Elsevier B.V. All rights reserved.

  • 43.
    Huotari, Joni
    et al.
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Lappalainen, Jyrki
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Puustinen, Jarkko
    Microelectronics and Material Physics Laboratories, University of Oulu.
    Baur, Tobias
    Department of Mechatronics, Saarland University, Germany.
    Alepee, Christine
    SGX Sensortech SA, Switzerland.
    Haapalainen, Tomi
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Komulainen, Samuli
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Pylvänäinen, Juho
    Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering. Microelectronics and Material Physics Laboratories, University of Oulu, Finland.
    Pulsed laser deposition of metal oxide nanoparticles, agglomerates, and nanotrees for chemical sensors2015In: Procedia Engineering, ISSN 1877-7058, E-ISSN 1877-7058, Vol. 120, p. 1158-1161Article in journal (Refereed)
    Abstract [en]

    Pulsed laser deposition (PLD) was used to prepare WO3, ZnO-modified SnO2, and V2O5 nanostructures as gas sensing materials on top of commercial SGX Sensortech MEMS microheater platforms. The layers were formed of different types of nanostructures including nanoparticles, agglomerates, and nanotrees with fractal-like growth. Clear dependency between the deposition parameters, structural morphology, and gas sensing performance was found. The sensing materials were found to be sensitive to different types of gaseous species, so that WO3 and SnO2 had very good response up to 600% to 50 ppm NO, and V2O5 up to -35% to 20 ppm NH3, respectively.

  • 44.
    Fashandi, Hossein
    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.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Smedfors, K.
    School of Information and Communication Technology, KTH, Stockholm, Sweden.
    Zetterling, C. -M
    School of Information and Communication Technology, KTH, Stockholm, Sweden.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Single-step synthesis process of Ti3SiC2 ohmic contacts on 4H-SiC by sputter-deposition of Ti2015In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 99, p. 53-56Article in journal (Refereed)
    Abstract [en]

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

  • 45.
    Eriksson, Jens
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Puglisi, Donatella
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Hsuan Kang, Yu
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Adjusting the electronic properties and gas reactivity of epitaxial graphene by thin surface metallization2014In: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 439, p. 105-108Article in journal (Refereed)
    Abstract [en]

    Graphene-based chemical gas sensors normally show ultra-high sensitivity to certain gas molecules but at the same time suffer from poor selectivity and slow response and recovery Limes. Several approaches based on functionalization or modification of the graphene surface have been demonstrated as means to improve these issues, but most such measures result in poor reproducibility. In this study we investigate reproducible graphene surface modifications by sputter deposition of thin nanostructured Au or Pt layers. It is demonstrated that under the right metallization conditions the electronic properties of the surface remain those of graphene, while the surface chemistry is modified to improve sensitivity, selectivity and speed of response to nitrogen dioxide.

  • 46.
    Halonen, Niina
    et al.
    University of Oulu, Finland.
    Datta-Chaudhuri, Timir
    University of Maryland, Baltimore, USA.
    Hassinen, Antti
    University of Oulu, Finland.
    Prakash, S. B.
    University of Maryland, Baltimore, USA.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Abshire, Pamela
    University of Maryland, Baltimore, USA.
    Smela, Elisabeth
    University of Maryland, Baltimore, USA.
    Kellokumpu, Sakari
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Cell clinic; CMOS chip measuring capacitance as indication of cell adhesion applied in evaluating the cytotoxicity of nanomaterials2014In: Proc. Eurosensors 2014, Brescia, Italy, September 7-10, 2014Conference paper (Refereed)
  • 47.
    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, p. 305-313Article 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.

  • 48.
    Halonen, Niina
    et al.
    University of Oulu, Finland.
    Datta-Chaudhuri, Timir
    University of Maryland, Baltimore, USA.
    Hassinen, Antti
    University of Oulu, Finland.
    Prakash, S. B.
    University of Maryland, Baltimore, USA.
    Möller, Peter
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    Abshire, Pamela
    University of Maryland, Baltimore, USA.
    Smela, Elisabeth
    University of Maryland, Baltimore, USA.
    Kellokumpu, Sakari
    University of Oulu, Finland.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, The Institute of Technology.
    CMOS-Based capacitance measurements applied in evaluating cell viability and cytotoxicity of nanomaterials2014In: Proc. E-MRS 2014, Lille, France May 26-30, 2014Conference paper (Refereed)
  • 49.
    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, p. 3221-3228Article 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.

  • 50.
    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.

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