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- Lloyd-Spets, Anita, et al.
(författare)
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High temperature catalytic metal field effect transistor for industrial applications
- 2000
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 70:1-3, s. 67-76
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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- Lloyd-Spets, Anita, et al.
(författare)
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MISiCFET chemical gas sensors for high temperature and corrosive environment applications
- 2002
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 389-3, s. 1415-1418
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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- Lloyd-Spets, Anita, et al.
(författare)
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SiC based field effect gas sensors for industrial applications
- 2001
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Ingår i: Physica status solidi. A, Applied research. - 0031-8965 .- 1521-396X. ; 185:1, s. 15-25
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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- Nakagomi, S, et al.
(författare)
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Influence of epitaxial layer on SiC Schottky diode gas sensors operated under high-temperature conditions
- 2002
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Ingår i: Materials Science Forum, Vols. 389-393. ; , s. 1423-1426
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Konferensbidrag (refereegranskat)abstract
- 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.
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- Savage, S, et al.
(författare)
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SiC based gas sensors and their applications
- 2000
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 353-3, s. 747-752
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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- Svenningstorp, H., et al.
(författare)
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Detection of HC in exhaust gases by an array of MISiC sensors
- 2001
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Ingår i: Sensors and actuators. B, Chemical. - 0925-4005 .- 1873-3077. ; 77:1-2, s. 177-185
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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- Svenningstorp, H, et al.
(författare)
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High temperature gas sensors based on catalytic metal field effect transistors
- 2000
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Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 338-3, s. 1435-1438
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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