SiC Based Field Effect Gas Sensors for Industrial Applications

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 C, 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. phys. stat. sol. (a) 185, No. 1, 15-25 (2001)

Detection of hydrocarbon species using silicon MOS field-effect transistors operated in a non-stationary temperature-pulse mode

“…This limits sensor operation temperatures of SiMOS devices to temperatures less than 200 • C. In order to overcome such limitations, catalytic gate devices were later also produced on SiC [8][9][10] and GaN [11][12][13] substrates.…”

“…In recent papers [25,26], we have shown that the gas sensing capabilities of SiMOS capacitors can be extended to the same range of hydrocarbon species, which previously could only be detected using high-temperature-operated SiC-or GaN-based MOS devices [8][9][10][11][12][13]. The way to achieve this is operating the SiMOS devices in a pulsed-temperature mode in which high-temperature chemical sampling interchanges with low-temperature electrical read-out of the C-V characteristics.…”

A Brief Overview on Automotive Exhaust Gas Sensors Based on Electroceramics

“…The voltage shift of the I ( V ) curve (where I =const.) is the sensor signal 28 . Sensors have been successfully tested in real exhaust gas.…”

The role of oxygen in hydrogen sensing by a platinum-gate silicon carbide gas sensor: An ultrahigh vacuum study

“…2,5,6 Figure 1 shows a schematic diagram of a typical device. Such devices have been successfully demonstrated for monitoring automotive exhaust, 7,8 flue gases from power plants, [9][10][11] and selective catalytic reduction in diesel engines. 12 Our understanding of the sensing mechanism is based largely on the pioneering work of Lundström and co-workers, [13][14][15][16][17][18][19] Kreisl et al, 20,21 and Salomonsson et al 22 on similar silicon-based devices.…”

“…7,24 In the present studies, unlike those conducted by other groups, 9,11,12,24 the gates were continuous, nonporous gates in direct contact with the oxide, 32 so these extra processes do not arise. In particular, direct adsorption of oxygen on the oxide surface, which has been proposed as an important mechanism for porous-gate devices, 24 is not significant for the sensors studied here.…”