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  • 1. Amandusson, H.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Dannetun, Helen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Alcohol dehydrogenation over Pd versus PdAg membranes2001Ingår i: Applied Catalysis A: General, ISSN 0926-860X, E-ISSN 1873-3875, Vol. 217, nr 1-2, s. 157-164Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dehydrogenation of methanol and ethanol and the subsequent permeation of hydrogen through Pd and Pd70Ag30 membranes, respectively, have been studied. In order to keep a continuous hydrogen permeation rate, oxygen needs to be added to the alcohol supply. Without oxygen, the decomposition products will form a contaminating layer on the upstream membrane surface. The extraction of hydrogen from ethanol is six times more effective through a Pd70Ag30 membrane than through a pure Pd membrane (at optimum conditions). For methanol, the hydrogen permeation is 30% larger through a Pd70Ag30 membrane than through a membrane of pure Pd. The increased hydrogen permeation yield through Pd70Ag30 compared to Pd can be attributed mainly to a lower upstream consumption of hydrogen due to water formation, but also to an increased conversion of the alcohol in the presence of oxygen. © 2001 Elsevier Science B.V.

  • 2. Amandusson, H.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Dannetun, Helen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Effect of CO and O2 on hydrogen permeation through a palladium membrane2000Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 153, nr 4, s. 259-267Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrogen permeation through a 25-µm thick palladium membrane during continuous exposures of hydrogen together with different combinations of oxygen and carbon monoxide has been studied at membrane temperatures of 100 °C-250 °C (total pressures of 40-150 Torr). Both CO and O2, individually, inhibit hydrogen permeation through the membrane. The cause of the inhibition is, however, somewhat different. CO blocks available hydrogen dissociation sites, while oxygen both blocks dissociation sites and also consumes adsorbed hydrogen through the production of water. When a combination of CO and O2 is supplied together with hydrogen, new reaction pathways will emerge. The carbon dioxide formation will dominate the water forming reaction, and consequently, the blocking effect caused by the formation of water will be suppressed. In a mixture of CO+O2+H2, the hydrogen permeation can become either larger or smaller than that due to only O2+H2 or CO+H2 depending on the CO/O2 ratio. It is thus possible to find a situation where carbon monoxide and oxygen react to form CO2 leaving adsorbed hydrogen free to permeate the membrane.

  • 3. Amandusson, H.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Dannetun, Helen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Hydrogen permeation through surface modified Pd and PdAg membranes2001Ingår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 193, nr 1, s. 35-47Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hydrogen permeation through surface modified Pd and Pd70Ag30 membranes has been studied at temperatures between 100 and 350°C. Silver has been evaporated on Pd and Pd70Ag30 foils with a thickness of 25µm in order to study the role of the surface composition in comparison with the membrane bulk composition. The Pd70Ag30-based membranes display the largest permeation rates at temperatures below 200°C, while Pd membranes with 20Å silver evaporated on the upstream side show the largest permeation rates above 200°C. There are, consequently, different rate limiting processes above and below 200°C: at temperatures below 200°C, the bulk diffusion through the membrane is rate limiting, while at temperatures above 200°C, the influence of the surface composition starts to become significant. It has further been concluded that a sharp silver concentration gradient from the surface to the bulk is important for the hydrogen permeation rate at temperatures above 200°C. Adding oxygen to the hydrogen supply will almost totally inhibit the hydrogen permeation rate when a pure Pd membrane surface is facing the upstream side, while for silver-containing surfaces the presence of oxygen has almost no effect. On a clean Pd surface, oxygen effectively consumes adsorbed hydrogen in a water forming reaction. With Ag on the surface, no water formation is detected. Co-supplied CO inhibits the permeation of hydrogen in a similar manner on all studied membrane surfaces, independent of surface silver content. © 2001 Elsevier Science B.V. All rights reserved.

  • 4. Amandusson, H.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Dannetun, Helen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Isotopic study of ethanol dehydrogenation over a palladium membrane2000Ingår i: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 195, nr 2, s. 376-382Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dehydrogenation of ethanol and the subsequent permeation were studied on a Pd membrane in a continuous ethanol supply. Hydrogen could not be extracted as efficiently from ethanol as from methanol. In ethanol, at least four of the six hydrogen atoms were not available for permeation because of methane formation. Hydrogens bonded to a carbon atom in a C-O group were available for permeation, while hydrogen atoms bonded to a carbon atom without oxygen were not. The efficiency of hydrogen permeation from ethanol was 5% compared to that of pure hydrogen, which could be compared to 25% for methanol compared to pure hydrogen. The hydrogen permeation could be enhanced by adding CO to the EtOH + O2 supply. The permeation probability of the hydrogen bonded to the methylene hydrogen increased while the water formation with this hydrogen atom decreased. Acetic acid was formed upstream when oxygen was in excess. The differently bonded hydrogen atoms in an ethanol molecule experienced different reaction pathways. The results did not contradict the models made from surface experiments in ultrahigh vacuum by Davis and Barteau, Holroyd and Bowker, or Bowker et al.

  • 5.
    Amandusson, Helena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Hydrogen extraction from methanol over a palladium membrane1997Konferensbidrag (Refereegranskat)
  • 6.
    Amandusson, Helena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Hydrogen permeation through modified palladium and palladium-silver2000Konferensbidrag (Refereegranskat)
  • 7.
    Amandusson, Helena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Hydrogen permeation through surface modified Pd and PdAg membranes and the effect of co-supplied O2 and CO2000Konferensbidrag (Refereegranskat)
  • 8.
    Amandusson, Helena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Identification of Pd membrane permeated hydrogen from ethanol1999Konferensbidrag (Refereegranskat)
  • 9.
    Amandusson, Helena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Influence of carbon monoxide and oxygen on hydrogen permeation through a palladium membrane -and its effect on dehydrogenation of methanol and ethanol1999Konferensbidrag (Refereegranskat)
  • 10.
    Amandusson, Helena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Jämförelse av alkohol-dehydrogenering över palladium respektive palladium-silver membran2000Konferensbidrag (Övrigt vetenskapligt)
  • 11.
    Amandusson, Helena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Methanol induced hydrogen permeation through a Pd membrane1999Ingår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 442, nr 2, s. 199-205Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dehydrogenation of methanol and the subsequent permeation of hydrogen through a 25 μm thick palladium film has been studied in a catalytic membrane reactor. At the temperature studied, 350°C, the decomposition pathway for methanol on clean palladium surfaces is believed to lead to Had and a carbonaceous overlayer. The released hydrogen can either desorb or permeate the palladium membrane. During a continuous supply of methanol hydrogen permeation is reduced and, eventually, totally quenched by the growing carbon monoxide/carbon coverage. Adding oxygen in the methanol supply can balance the increasing carbonaceous coverage through the production of carbon dioxide. In such a case, it is concluded that no CO bond scission occurs. The methanol/oxygen ratio is crucial for the hydrogen permeation rate. Isotope-labelled methanol, CH3OH, CH3OD, CD3OH and CD3OD, shows that it is preferentially the methyl (or methoxy) hydrogen that permeates the membrane.

  • 12.
    Amandusson, Helena
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Permeation of methyl hydrogen in isotopically labelled methanol through palladium membranes1998Konferensbidrag (Refereegranskat)
  • 13.
    Baranzahi, Amir
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Tobias, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Mårtensson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Chemical sensors with catalytic metal gates - Switching behavior and kinetic phase transitions1998Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 145, nr 10, s. 3401-3406Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 14.
    Baranzahi, Amir
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Tobias, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Mårtensson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Kinectic phase transitions and chemical sensors with catalytic metal gates1997Ingår i: Chemical & Biological Sensors & Analytical Electrochemical Methods, 1997, Electrochemical Society , 1997, Vol. 97, nr 19, s. 1-15Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

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

  • 15.
    Briand, D.
    et al.
    Institute of Microtechnology, University of Neuchâtel, P.O. Box 3, CH-2007 Neuchâtel, Switzerland.
    Wingbrant, Helena
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Sundgren, Hans
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Van, der Schoot B.
    Van der Schoot, B., Institute of Microtechnology, University of Neuchâtel, P.O. Box 3, CH-2007 Neuchâtel, Switzerland.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    De, Rooij N.F.
    De Rooij, N.F., Institute of Microtechnology, University of Neuchâtel, P.O. Box 3, CH-2007 Neuchâtel, Switzerland.
    Modulated operating temperature for MOSFET gas sensors: Hydrogen recovery time reduction and gas discrimination2003Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 93, nr 1-3, s. 276-285Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    This communication presents a modulated mode of operation for MOSFET gas sensors. A low-power micromachined device allows pulsing the temperature of MOSFET gas sensors with a time constant less than 100ms. Modulating the temperature during the gas exposure modifies the kinetics of the gas reactions with the sensing film. The way the sensor response is modified by the temperature modulation depends on the sensor "history", on the nature of the surrounding gaseous atmosphere, and on the type of materials used as catalytic sensing film. Pulsing the temperature up just after the gas exposure can reduce the recovery time for specific applications, such as for hydrogen detection. Cycling the temperature can allow the discrimination between different gas mixtures. Discrimination was shown for gaseous mixtures of hydrogen and ammonia in air. The results obtained indicate that a "smart" combination of sample and temperature profile could be used to expand the information content in the sensor response. © 2003 Elsevier Science B.V. All rights reserved.

  • 16.
    Ekedahl, Lars-Gunnar
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Eriksson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biosensorer och bioelektronik. Linköpings universitet, Tekniska fakulteten.
    Hydrogen sensing mechanisms of metal insulator interfaces1998Ingår i: Accounts of Chemical Research, ISSN 0001-4842, E-ISSN 1520-4898, Vol. 31, nr 5, s. 249-256Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The hydrogen sensitivity of palladium-silicon dioxidesilicon (Pd-MOS) structures was demonstrated about 25 years ago. One of the most interesting features of the Pd-MOS device as a hydrogen sensor is its very large dynamic pressure range. Such devices are now used in several practical applications and in commercially available equipment, both as single sensors and in sensor arrays. We recall that the hydrogen sensitivity of the device occurs due to a hydrogen induced polarization at the Pd-SiO2 interface as schematically shown in Figure 1. During the years, several types of devices have been developed, both with insulators other than silicon dioxide and catalytic metals other than palladium. Furthermore, it has been demonstrated that sensors with thin, discontinuous catalytic metals can detect molecules, like ammonia, which are not detected by sensors with thick continuous palladium gates. 1-3 Although several insulators have been used in hydrogen sensitive Pd-insulator-semiconductor

  • 17.
    Eriksson, Mats
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Hydrogen adsorption states at the Pd-SiO2 interface and simulation of the response of a Pd metal-oxide-semiconductor hydrogen sensor1998Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 83, nr 8, s. 3947-3951Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The response of a Pd–SiO 2 –Si hydrogen sensor depends on the reaction kinetics of hydrogen on the Pd surface and on the hydrogen adsorption states at the Pd/SiO 2 interface. In this work we show that besides the dominating hydrogen adsorption state located on the oxide side of the interface, a second state, resulting in opposite hydrogen polarization, exists. This state is possibly a reminiscence of the hydrogen adsorption state on a clean Pd surface. Taking both states into account, a simulation of the hydrogen response over more than ten decades in hydrogen pressures gives good agreement with published data.

  • 18.
    Eriksson, Mats
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Real time measurements of hydrogen desorption and absorption during CO exposures of Pd: Hydrogen sticking and dissolution1998Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 133, nr 1-2, s. 89-97Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Combined real time measurements of hydrogen desorption and absorption show that both processes may be induced simultaneously by CO adsorption on a hydrogen-covered Pd surface. The induced absorption is found to be a kinetic effect, where the amount absorbed depends on the hydrogen desorption rate and the CO adsorption rate. In addition to simple site blocking, adsorbed CO induces an increase in the hydrogen desorption energy and an activation barrier for hydrogen dissociation. Both increase linearly with CO coverage for θCO>0.18 ML. Below this coverage, the hydrogen dissociation is non-activated.

  • 19.
    Eriksson, Mats
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan. Tekniska högskolan.
    The catalytic oxidation of CO on polycrystalline Pd: Experiments and kinetic modelling1998Ingår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 412/413, s. 430-440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The catalytic oxidation of CO on a thin, polycrystalline Pd film has been studied. Even though the Pd film is expected to be dominated by (111) facets, some distinct differences compared to single crystalline Pd(111) are observed. A kinetic model for the CO oxidation reaction is presented. It gives good agreement with experiments, both in terms of CO2 reaction probability and CO coverage during reaction conditions. The model assumes a random distribution of the adsorbates, an activation energy for the reaction that decreases with increasing CO coverage, as well as a CO sticking coefficient that in a temperature dependent fashion depends on the oxygen coverage. Single crystal data available from the literature (initial sticking coefficients and heats of adsorption) were mainly used as input parameters. Thus, the model might also be a useful starting point when modeling the catalytic oxidation of CO on single crystal surfaces.

  • 20.
    Eriksson, Mats
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    The influence of CO on the response of hydrogen sensitive Pd-MOS devices1997Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 42, nr 3, s. 217-223Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to understand and correctly interpret the response of chemical sensors under measurement conditions, detailed studies of molecule—sensor interactions under well-controlled conditions are needed. In this work, the influence of CO on the response of a hydrogen sensitive Pd—metal-oxide-semiconductor (Pd—MOS) device with a dense Pd film is studied in ultrahigh vacuum (UHV). The results show that although CO by itself does not induce any response of the device, CO may have a significant influence on the hydrogen response, especially so in the presence of oxygen. It is also shown that high CO coverages on the Pd surface increases the time needed to obtain equilibrium between the gas phase hydrogen pressure and the response of the Pd—MOS device. This is due to a CO induced increase of the activation energies of the dissociation and association processes for hydrogen. The effect on the hydrogen response is small for CO coverages below 0.2 monolayers and increases dramatically above this coverage.

  • 21.
    Eriksson, Mats
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biosensorer och bioelektronik. Linköpings universitet, Tekniska fakulteten.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    A model of the Temkin isotherm behaviour for hydrogen adsorption at Pd-SiO2 interfaces1997Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 82, nr 6, s. 3143-3146Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A simple electrostatic model of the adsorbate–adsorbateinteraction of hydrogen atoms at a Pd–SiO 2 interface is presented. The model predicts a hydrogen adsorption isotherm of the Temkin type. It is found that, in practice, an upper limit for the hydrogen response of a Pd-metal-oxide-semiconductor device exists. The value (in V) is equal to the difference of the initial heats of adsorption (in eV) of the interface and the Pd bulk, respectively. Furthermore, a corresponding maximum hydrogen concentration, at the interface, of 1×10 18  m −2 is predicted. The predictions are in good agreement with previously observed experimental data.

  • 22.
    Eriksson, Mats
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Olsson, Lars
    Linköpings universitet, Institutionen för medicin och hälsa.
    Erlandsson, Ragnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemiska och optiska sensorsystem. Linköpings universitet, Tekniska fakulteten.
    Helmersson, Ulf
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Morphology changes of thin Pd films grown on SiO2: influence of adsorbates and temperature1999Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 342, nr 1-2, s. 297-306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Under certain conditions morphology changes occur when thin Pd films, grown on SiO2 at room temperature, are subject to elevated temperatures. First holes in the metal are observed, followed by network formation and finally isolation of metal islands. This process is known as agglomeration. The influence of gas exposures on this restructuring process has been studied by following variations in the capacitance of the structure and by atomic force microscopy, transmission electron microscopy and ultraviolet photoelectron spectroscopy. The capacitance measurements show that carbonaceous species have an impeding influence on the rate of agglomeration and may lock the film structure in a thermodynamic non-equilibrium state. By removing these species with oxygen exposure, i.e. by forming volatile CO and CO2, a clean surface is obtained and the agglomeration process can proceed. High oxygen or hydrogen coverages also lower the rate of restructuring, compared to the case of a clean surface. For the clean Pd surface, an apparent activation energy of 0.64 eV is found for the restructuring process.

  • 23.
    Fornander, H.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Ekedahl, L.-G.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    A comparison of the CO and D2 oxidation reactions on Pd supported on MgO(100), MgO(110) and MgO(111)1999Ingår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 440, nr 3, s. 375-386Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Oxidation of D2 and CO on oxygen pre-exposed 200 nm thick Pd films, epitaxially grown on MgO(100), MgO(110) and MgO(111), has been investigated in the temperature range 100–300°C. Oxygen initial sticking coefficients have been determined to be close to 1 for the 100 and 110 films, and around 0.8 for the 111 film. The sticking coefficient and reactive sticking coefficient for CO oxidation on Pd/MgO(100) is also close to 1, and the maximum reactive sticking coefficient for hydrogen oxidation is determined to be around 0.9 at temperatures above 200°C. It is shown that the reactivities for the different surfaces vary strongly with surface and oxygen coverage, and the consequence of this for supported particle catalysts is pointed out.

  • 24.
    Fornander, H.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, L.-G.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Oxidation of carbon monoxide and deuterium on a Pd (100) film1999Ingår i: Catalysis Letters, ISSN 1011-372X, E-ISSN 1572-879X, Vol. 59, s. 107-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    For Pd/MgO(100) pre-exposed to oxygen, the catalytic oxidation of CO and D2, respectively, has been studied in the temperature range 100–300 _C. At temperatures >200 _C, the CO2 desorption rate is independent of oxygen coverage, _O, and the reactive sticking coefficient for CO is close to unity. The D2O desorption rate is strongly dependent on _O. D2 adsorption is blocked by adsorbed oxygen and the maximum D2O desorption rate is reached when almost all oxygen has been consumed (_O < 0:03). The formation of an oxygen c(2 _ 2) structure, coexisting with the initial p(2 _ 2) phase, is reflected in the oxidation rates.

  • 25.
    Fornander, H.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ekedahl, L.-G.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Structural effects of supported Pd particles in D2 and CO oxidation experiments1999Ingår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 441, nr 2-3, s. 479-492Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the temperature range 100–300°C, isothermic D2 and CO titration experiments have been performed on oxygen pre-exposed 1.5, 4, 20 and 200 nm thick Pd films, epitaxially cube-on-cube grown on MgO(100). The oxygen pre-exposures varied from 0.2 to 150 L. The three thinnest films consisted of faceted particles, mainly bounded by Pd(111) and Pd(100) surfaces, while the 200 nm sample was a continuous, flat Pd(100) film with atomic steps. Atomic force microscopy demonstrated that the titration experiment did not affect the structure of the (large) Pd particles in the 20 nm film. The reaction behavior of the 1.5 nm film can be understood by assuming that the film consists of (111)-bounded Pd particles, where O2 and D2 dissociate and spill over to the oxide support, whereas CO adsorbs and reacts both on the Pd and on the oxide. The CO oxidation thus occurs in parallel on Pd and on MgO, while the D2 oxidation is sequential, first occurring on the Pd and then on the MgO. To explain the D2O desorption curves for the 4 and 20 nm films, spillover to the MgO support as well as reactions on the Pd(111) and Pd(100) facets have to be taken into account. The greater the oxygen pre-exposure, the higher the probability that the D2 molecules dissociate primarily on the Pd(111) surfaces.

  • 26. Johansson, M.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Hydrogen adsorbed on palladium during water formation studied with palladium membranes2001Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 173, nr 1-2, s. 122-133Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The amount of hydrogen adsorbed on palladium during water formation has been studied by measurements of the rate at which hydrogen permeates a palladium membrane. The water formation and hydrogen permeation rates were measured simultaneously for palladium membranes exposed to a hydrogen-oxygen-argon mixture on one side and to pure argon on the other side. Investigations were carried out for the temperatures 100, 150 and 200 °C at a total pressure of 760 Torr. If the rates are plotted as a function of a, where a = pH(2)/(pH(2)+pO(2)), pH(2) and pO(2) are the pressures of hydrogen and oxygen at the palladium surface, respectively, it is found that, at 100 °C, a peak occurs in the water formation rate at amax˜0.2. The palladium surface is dominated by hydrogen for a>amax and is hydrogen deficient for a>amax. This is consistent with a rate limiting step for the water forming reaction where adsorbed hydrogen is one of the reactants. It is also concluded that the heat of adsorption for hydrogen on the palladium surface is significantly lower than previously derived from experiments made under ultrahigh vacuum conditions.

  • 27. Johansson, M.
    et al.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    The water formation rate on platinum and palladium as a function of the surface hydrogen pressure from three-dimensional hydrogen pressure distributions2001Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 180, nr 1-2, s. 27-35Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The water formation rate on platinum and palladium as a function of the reactant pressures at the catalytic surface has been determined from measurements of the three-dimensional hydrogen pressure distributions over the catalytic surface. Measurements were made for gas mixtures containing less than 1% of hydrogen and 20% of oxygen in argon at atmospheric pressure. The experiments were performed in a reactor with a simple and well-defined geometry which makes it possible to calculate the hydrogen pressure distribution in the entire region where measurements are made. The water formation rate as a function of the hydrogen pressure at the catalytic surface is obtained by comparing calculated hydrogen pressure distributions to measured ones. It is concluded that three-dimensional reactant pressure distributions can be used to accurately determine the reaction rate on a catalytic surface as a function of the reactant pressures at the surface. This is valuable for studies in the viscous pressure regime, where mass transfer limitations may be difficult to avoid. © 2001 Elsevier Science B.V.

  • 28. Johansson, M
    et al.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    An equipment for three-dimensional spatially resolved gas analysis2000Ingår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 71, nr 9, s. 3513-3521Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The apparatus described is able to measure three-dimensional temperature and partial pressure distributions in gas mixtures with a spatial resolution better than 0.5 mm. The measurements are performed in a well defined laminar gas flow in a duct of rectangular cross section. The gas mixture is sampled locally with a quartz tube orifice leak movable in three dimensions. Mass spectrometry is used for partial pressure measurements. The total pressure in the duct can be regulated in the range 50-760 Torr and the gas temperature can be varied between room temperature and 500 degrees C. The apparatus is primarily designed for studies of the distribution of reactants and products over catalytic surfaces. Because of the well defined gas flow in the duct the partial pressure distributions of reactants and products over the catalytic surface can be calculated with good accuracy. By comparing calculated pressure distributions to measured ones the local reaction rate on the catalytic surface as well as the pressures of reactants and products at the surface can be obtained. As an example it is shown how the hydrogen distribution over a platinum surface exposed to a mixture of hydrogen, oxygen, and argon can be used to calculate the local water formation rate on the platinum surface. (C) 2000 American Institute of Physics. [S0034-6748(00)01409-X].

  • 29.
    Johnson, Håkan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Karlsson, Ola
    Winqvist, Fredrik
    Krantz-Rulcker, Christina
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Predicting microbial growth in pulp using an electronic tongue2003Ingår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 18, nr 2, s. 134-140Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes how an electronic tongue based on pulsed voltammetry over noble metal electrodes can be used as an instrument to predict the amount of microorganisms in pulp during their growth cycle. The electronic tongue consists of a sensor body and a PC, which is used to control a potentiostat which applies the voltammetric large amplitude pulsed voltammetry (LAPV)-waveform across the sensor electrodes, and to collect the data of the resulting current. The sensor body is constructed of four noble metal electrodes, a stainless steel electrode as counterelectrode, and an Ag/AgCl reference electrode. This arrangement works as a standard three-electrode voltammetry system. Principal component analysis (PCA) and partial least squares (PLS) multivariate prediction methods are used to extract information from the data and to aid interpretation. It is shown that PLS-models of the voltammetric signals from this sensor array predicts the reference methods, viable count using Petrifilm(TM) aerobic total counts, with good accuracy (root mean square error of prediction (RMSEP) 9% of maximum value or 20% in a lower region corresponding to 500-1000 colony forming units) and adenosine triphosphate (ATP)-measurements with lower accuracy (10% of maximum value or 55% in a lower region). Since the precision of this method of detection is on a level with the viable count method, this method can be considered superior where short response times or the possibility of on-line measurement are of value.

  • 30.
    Linnarsson, MK
    et al.
    Royal Inst Technol, SE-16440 Kista, Sweden Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden ACREO, SE-16440 Kista, Sweden.
    Lloyd-Spets, Anita
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Janson, MS
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Karlsson, S
    Schoner, A
    Royal Inst Technol, SE-16440 Kista, Sweden Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden ACREO, SE-16440 Kista, Sweden.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Svensson, BG
    Metal-contact enhanced incorporation of deuterium in 4H-and 6H-SiC2000Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 338-3, s. 937-940Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deuterium was introduced in p-type SiC from a gas ambient. The samples were partially coated with 200 Angstrom thick metal layer of titanium, nickel, platinum or gold. Heat treatments were performed in the temperature range 500-800 degreesC during 4 h. Secondary ion mass spectrometry (SIMS) was used to measure the deuterium content after deuterium exposure. The catalytic metal coating is shown to play an important role for introducing deuterium into SiC. Nickel and platinum facilitate hydrogen incorporation in p-type SiC, which may be due to an increased hydrogen concentration at the metal/SiC interface and/or an increase the H+ ions to H ratio. No in-diffusion of deuterium is observed using titanium although large quantities of deuterium are stored in the titanium film. Furthermore, gold reveals an inert character and does not promote in-diffusion of deuterium.

  • 31.
    Lloyd-Spets, Anita
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Tobias, P.
    Unéus, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Svenningstorp, H.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    High temperature catalytic metal field effect transistor for industrial applications2000Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 70, nr 1-3, s. 67-76Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Field effect chemical sensors, utilising silicon carbide as semiconductor, can be operated at high temperature and in rough environments. Gas sensitive field effect transistors, MISiCFET, are now developed (ACREO, Kista in Sweden). This will increase the number of possible applications for field effect gas sensors. The first batch of MISiCFET devices is possible to operate in intermittent pulses of hydrogen/oxygen up to 775°C. At temperature above 600°C, the gas response of the MISiC devices has very short time constants for a change between oxidising and reducing atmosphere and cylinder specific monitoring of a combustion engine has been demonstrated. Other industrial applications, like exhaust diagnosis and flue gas monitoring, have been demonstrated by the use of MISiC Schottky diodes at lower temperatures, 200°C-500°C.

  • 32.
    Lloyd-Spets, Anita
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Unéus, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Svenningstorp, H
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Tobias, P
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Larsson, O
    Goras, A
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Savage, S
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Harris, C
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Martensson, P
    Wigren, R
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Salomonsson, P
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Haggendahl, B
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Ljung, P
    Mattsson, M
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Medel AB, SE-66222 Amal, Sweden ABREO AB, SE-16440 Kista, Sweden Appl Sensor, SE-58330 Linkoping, Sweden Volvo TU, SE-41288 Gothenburg, Sweden Vattenfall Utveckling, SE-81426 Alvkarleby, Sweden.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    SiC based field effect gas sensors for industrial applications2001Ingår i: Physica status solidi. A, Applied research, ISSN 0031-8965, E-ISSN 1521-396X, Vol. 185, nr 1, s. 15-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development and field-testing of high-temperature sensors based on silicon carbide devices have shown promising results in several application areas. Silicon carbide based field-effect sensors can be operated over a large temperature range, 100-600 degreesC, and since silicon carbide is a chemically very inert material these sensors can be used in environments like exhaust gases and flue gases from boilers. The sensors respond to reducing gases like hydrogen, hydrocarbons and carbon monoxide. The use of different temperatures, different catalytic metals and different structures of the gate metal gives selectivity to different gases and arrays of sensors can be used to identify and monitor several components in gas mixtures. MOSFET sensors based on SIC combine the advantage of simple circuitry with a thicker insulator, which increases the long term stability of the devices. In this paper we describe silicon carbide MOSFET sensors and their performance and give: examples of industrial applications such as monitoring of car exhausts and flue gases. Chemometric methods have been used for the evaluation of the data.

  • 33.
    Lloyd-Spets, Anita
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Unéus, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Svenningstorp, H
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Ford Motor Co, Dearborn, MI 48124 USA Vattenfall Dev, SE-81426 Alvkarleby, Sweden AppliedSensor AB, SE-58330 Linkoping, Sweden Volvo PV AB, SE-40508 Gothenburg, Sweden ACREO Ab, SE-16440 Kista, Sweden Volvo TU, SE-41288 Gothenburg, Sweden.
    Wingbrant, Helena
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Harris, CI
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Ford Motor Co, Dearborn, MI 48124 USA Vattenfall Dev, SE-81426 Alvkarleby, Sweden AppliedSensor AB, SE-58330 Linkoping, Sweden Volvo PV AB, SE-40508 Gothenburg, Sweden ACREO Ab, SE-16440 Kista, Sweden Volvo TU, SE-41288 Gothenburg, Sweden.
    Salomonsson, P
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Ford Motor Co, Dearborn, MI 48124 USA Vattenfall Dev, SE-81426 Alvkarleby, Sweden AppliedSensor AB, SE-58330 Linkoping, Sweden Volvo PV AB, SE-40508 Gothenburg, Sweden ACREO Ab, SE-16440 Kista, Sweden Volvo TU, SE-41288 Gothenburg, Sweden.
    Tengstrom, P
    Martensson, P
    Ljung, P
    Mattsson, M
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Ford Motor Co, Dearborn, MI 48124 USA Vattenfall Dev, SE-81426 Alvkarleby, Sweden AppliedSensor AB, SE-58330 Linkoping, Sweden Volvo PV AB, SE-40508 Gothenburg, Sweden ACREO Ab, SE-16440 Kista, Sweden Volvo TU, SE-41288 Gothenburg, Sweden.
    Visser, JH
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Ford Motor Co, Dearborn, MI 48124 USA Vattenfall Dev, SE-81426 Alvkarleby, Sweden AppliedSensor AB, SE-58330 Linkoping, Sweden Volvo PV AB, SE-40508 Gothenburg, Sweden ACREO Ab, SE-16440 Kista, Sweden Volvo TU, SE-41288 Gothenburg, Sweden.
    Ejakov, SG
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Ford Motor Co, Dearborn, MI 48124 USA Vattenfall Dev, SE-81426 Alvkarleby, Sweden AppliedSensor AB, SE-58330 Linkoping, Sweden Volvo PV AB, SE-40508 Gothenburg, Sweden ACREO Ab, SE-16440 Kista, Sweden Volvo TU, SE-41288 Gothenburg, Sweden.
    Kubinski, D
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Ford Motor Co, Dearborn, MI 48124 USA Vattenfall Dev, SE-81426 Alvkarleby, Sweden AppliedSensor AB, SE-58330 Linkoping, Sweden Volvo PV AB, SE-40508 Gothenburg, Sweden ACREO Ab, SE-16440 Kista, Sweden Volvo TU, SE-41288 Gothenburg, Sweden.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Savage, SM
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Ford Motor Co, Dearborn, MI 48124 USA Vattenfall Dev, SE-81426 Alvkarleby, Sweden AppliedSensor AB, SE-58330 Linkoping, Sweden Volvo PV AB, SE-40508 Gothenburg, Sweden ACREO Ab, SE-16440 Kista, Sweden Volvo TU, SE-41288 Gothenburg, Sweden.
    MISiCFET chemical gas sensors for high temperature and corrosive environment applications2002Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 389-3, s. 1415-1418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A chemical gas sensor based on a silicon carbide field effect transistor with a catalytic gate metal has been under development for a number of years. The buried gate design allows the sensor to operate at high temperatures, routinely up to 600degreesC and for at least three days at 700degreesC. The chemical inertness of silicon carbide makes it a suitable sensor technology for applications in corrosive environments such as exhaust gases and flue gases from boilers. The selectivity of the sensor devices is established through the choice of type and structure of the gate metal as well as the operation temperature. In this way NH3 sensors with low cross sensitivity to NOx have been demonstrated as potential sensors for control of selective catalytic reduction (SCR) of NOx by urea injection into diesel exhausts. The hardness of the silicon carbide makes it for example more resistant to water splash at cold start of a petrol engine than existing technologies, and a sensor which can control the air to fuel ratio, before the exhaust gases are heated, has been demonstrated. Silicon carbide sensors are also tested in flue gases from boilers. Efficient regulation of the combustion in a boiler will decrease fuel consumption and reduce emissions.

  • 34.
    Nakagomi, S
    et al.
    Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden.
    Shinobu, H
    Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden.
    Unéus, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Yakimova, Rositsa
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Syväjärvi, Mikael
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Henry, Anne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Lloyd-Spets, Anita
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Influence of epitaxial layer on SiC Schottky diode gas sensors operated under high-temperature conditions2002Ingår i: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, s. 1423-1426Konferensbidrag (Refereegranskat)
    Abstract [en]

    Schottky diode gas sensors were fabricated on top of the epitaxial layer grown by three different methods, purchased from Cree Research Inc., by hot wall CVD, or by sublimation at a high growth rate. The epitaxial layers have different thickness and doping. The current-voltage characteristics of the gas sensors were compared in different gas ambient during operation in the high temperature region. The temperature dependence of the series resistance of the diodes revealed two types of carrier scattering mechanisms, impurity scattering for the sublimation epitaxial layer at 300-400degreesC and at 400-600degreesC, lattice scattering for all diodes. The ideality factor of the diode fabricated on the Cree substrate is higher than others. The higher ideality factor gives rise to a larger forward voltage change for a change in gas ambient. The amount of change in barrier height caused by a change in the ambient gas is almost the same for the three types of diodes. The value of the barrier height of the diode grown by the sublimation method is lower than for the others, which gives a higher reverse saturation current at temperatures above 400degreesC. The largest saturation current also shows the largest current change when switching between different gas atmospheres.

  • 35. Nielsen, A.T.
    et al.
    Amandusson, H.
    Bjorklund, R.
    Dannetun, Helen
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Ejlertsson, J.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Svensson, Bo
    Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Hydrogen production from organic waste2001Ingår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 26, nr 6, s. 547-550Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The extraction of pure hydrogen from the fermentation of household waste by a mixed anaerobic bacterial flora is demonstrated. Simulated household waste (600 g) was fermented in a bioreactor, which was continuously sparged with nitrogen (30 ml/min) fed in from the bottom. The gas stream from the biorector passes through a sulphide trap (ZnO) and then through a heated palladium-silver membrane reactor to separate hydrogen from the gas stream. In this way, waste remediation and biological hydrogen production is combined in a process where a large proportion of the hydrogen produced can be collected, free of other gaseous species from the fermentation. © 2001 International Association for Hydrogen Energy.

  • 36. Norberg, P
    et al.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Hydrogen-induced CO2 formation from ethylene deposits on Pt during consecutive O-2 and H-2 exposures2000Ingår i: Catalysis Letters, ISSN 1011-372X, E-ISSN 1572-879X, Vol. 65, nr 1-3, s. 25-31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The oxidation of C2H4 deposits on polycrystalline Pt when exposed to consecutive O-2 and H-2 pulses at room temperature has been investigated in a long (L=36 mm), shallow (d=600-700 nm) micromachined glass-SiO2-Pt channel. Hydrogen-induced CO2 formation from species accumulated on the Pt surface was observed. Frequent switching of the O-2/H-2 exposure pulses was found to increase the efficiency of the oxidation of the carbonaceous deposits markedly. The observations may be of general interest for the regeneration of contaminated catalysts.

  • 37.
    Salomonsson, Anette
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Eriksson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dannetun, Helen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Hydrogen ad- and absorption on Pt-SiO2-Si structures2001Konferensbidrag (Refereegranskat)
  • 38.
    Savage, S
    et al.
    ACREO AB, SE-16440 Kista, Sweden Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden.
    Svenningstorp, H
    ACREO AB, SE-16440 Kista, Sweden Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden.
    Unéus, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Kroutchinine, A
    ACREO AB, SE-16440 Kista, Sweden Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden.
    Tobias, P
    ACREO AB, SE-16440 Kista, Sweden Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Harris, C
    ACREO AB, SE-16440 Kista, Sweden Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden.
    Lloyd-Spets, Anita
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    SiC based gas sensors and their applications2000Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 353-3, s. 747-752Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The development and field-testing of hardy high-temperature sensors based on silicon carbide devices has to date shown promising results in several application areas. As the need to take care of the environment becomes more urgent, these small and relatively cheap sensors could be used to increase the monitoring of gases, or to replace or complement larger and more expensive sensor technologies used today. In this paper the development of Silicon Carbide MOSFET transistor sensors and Schottky diode sensors is described. The devices are tested in industrial applications such as monitoring of car exhausts and flue gases.

  • 39.
    Svenningstorp, H
    et al.
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden.
    Unéus, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Tobias, P
    Linkoping Univ, S SENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lloyd-Spets, Anita
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    High temperature gas sensors based on catalytic metal field effect transistors2000Ingår i: Materials Science Forum, ISSN 0255-5476, E-ISSN 1662-9752, Vol. 338-3, s. 1435-1438Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catalytic metal insulator silicon carbide field effect devices, MISiCFET, have been developed as gas sensitive devices. They functioned in a corrosive atmosphere of hydrogen / oxygen alternating pulses up to 775 degreesC. At 600 degreesC some devices operated with full gas response to hydrogen for 17 hours. Below a temperature of 500 degreesC the gas response of the devices was very stable with no base line drift for several days. MISiC Schottky diodes have been used for cylinder specific monitoring of an engine and exhausts and flue gas diagnosis. The MISiCFET devices will increase the number of possible applications for FET gas sensor devices.

  • 40. Svenningstorp, H.
    et al.
    Widén, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Salomonsson, P.
    Volvo TU, Applied Physics, 6130, Chalmers Teknikpark, SE-412 88 Göteborg, Sweden.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lundström, Ingemar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Tobias, P.
    Lloyd-Spets, Anita
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Detection of HC in exhaust gases by an array of MISiC sensors2001Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 77, nr 1-2, s. 177-185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Future legislations for car emissions make direct measurements in exhaust gases of hydrocarbon (HC) as well as CO and NOx interesting. Robust sensors that can stand the high temperature and rough environment in the exhaust gases are needed. Silicon carbide has the advantage of being a chemically very inert material, which, due to its high band gap, is a semiconductor even at temperatures around 800°C. Catalytic metal insulator silicon carbide Schottky diode sensors respond to gases like H2, HC, NOx in exhaust gases. The choice of catalytic metal, structure of the metal, and the operation temperature determines the response pattern to different gases. Here we will demonstrate that an array of different MISiC sensors to some extent predicts the HC concentration in gasoline exhaust gases. Chemometric methods are used for the evaluation of the signals. © 2001 Elsevier Science B.V.

  • 41.
    Svenningstorp, Henrik
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Tobias, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Lundström, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biosensorer och bioelektronik. Linköpings universitet, Tekniska högskolan.
    Salomonsson, Per
    AB Volvo Technological Development, Göteborg, Sweden.
    Mårtensson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Influence of catalytic reactivity on the response of metal-oxide-silicon carbide sensor to exhaust gases1999Ingår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 57, nr 1-3, s. 159-165Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Catalytic metal insulator silicon carbide, MISiC, Schottky diodes are promising devices for on board exhaust diagnosis in cars. These sensors show a direct or indirect sensitivity to gases like H-2, CO, HC (hydrocarbons) and O-2. The catalytic reactivity of the sensor will effect the gas sensing conditions. In some situations knowledge about the reactivity of the catalytic surface may give more information about the exhaust gas composition. For instance, the sensor signal normally moves to a lower voltage in an ambient containing H-2 and HC, however, under certain conditions when exposed to rich gas mixtures, the HC response is opposite the one for H-2. Measurements performed by the MISiC sensors on simulated exhaust gas mixtures, either rich or lean, are shown here. Some fundamental studies of the HC response have been performed. Reaction limitation conditions are suggested as an explanation for the response of HC opposite the one of H-2.

  • 42.
    Unéus, Lars
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    Nakagomi, S
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Royal Inst Technol, SE-16440 Kista, Sweden Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan.
    Linnarsson, M
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Royal Inst Technol, SE-16440 Kista, Sweden Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan.
    Jensen, Mona
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Svensson, BG
    Yakimova, Rositsa
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Syväjärvi, Mikael
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Henry, Anne
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Janzén, Erik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Ekedahl, Lars-Gunnar
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Lunstrom, I
    SSENCE, SE-58183 Linkoping, Sweden Linkoping Univ, Div Appl Phys, SE-58183 Linkoping, Sweden Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden Royal Inst Technol, SE-16440 Kista, Sweden Ishinomaki Senshu Univ, Sch Engn, Ishinomaki 9868580, Japan.
    Lloyd-Spets, Anita
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik.
    The effect of hydrogen diffusion in p- and n-type SiC Schottky diodes at high temperatures2002Ingår i: Materials Science Forum, Vols. 389-393, 2002, Vol. 389-3, s. 1419-1422Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present here the effect of a hydrogen anneal at 600degreesC for Schottky sensor devices based on n- and p-type 4H SiC. The devices have gate contacts of Ta/Pt, or TaSix/Pt. The catalytic metal gate dissociates hydrogen and thus promotes diffusion of hydrogen atoms into the SiC, where the atoms will trap or react with different impurities, defects or surface states. This will change parameters such as the carrier concentrations, the defect density of the material or the surface resistivity at the SiC/SiO2 interface. The current-voltage and the capacitance-voltage characteristics were measured before and after annealing in hydrogen and oxygen containing atmosphere, and the results show a reversible effect in the I-V characteristics.

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