Studies of the detection mechanism of MISiCFET gas sensors

Research Project, 2006 – 2008

This project focuses on the understanding of the detection mechanism of chemical sensors for measuring gas compounds, with special emphasis on MISiCFET sensors for detection of NH3 and NOx. Metal insulator silicon carbide field effect transistors (MISiCFET) are presently tested in applications like NH3 and NOx sensors for control of selective catalytic reduction of NOx in diesel exhausts and sensors for control of the combustion process for boilers. A detailed knowledge of the detection mechanism of chemical sensors is required to achieve high sensitivity, selectivity, speed of response, and long-term stability required by the industry. The overall goal of this application is to obtain knowledge on the molecular level of the detection mechanism of field effect chemical gas sensors, i.e. correlate the sensor response with the time evolution of surface adsorbates on the sensor. By using infrared spectroscopy we will identify the active sites on the sensor surface, and the adsorbed species involved during the detection of H2, NH3, NO and NO2 respectively, in air between 100 and 400°C. The interpretation of the experimental data will be supported by first principle calculations. The project will also result in knowledge, which most probably will be useful in the area of environmental catalysis.