Key Lab of Inorganic Functional Materials and Devices, CAS
MIS-Structure Sensors with Solid Electrolyte Gate Layer for Detection of Explosive and Hazardous Gases
Professor Alexey Vasiliev
Kurchatov complex of chemical and physical technology
NRC Kurchatov Institute
The sensors based on a structure metal-insulator-semiconductor (MIS) are well known detectors of low concentrations of hydrogen and have several important advantages compared to other types of sensors: they operate at room temperature, are produced using Si-compatible technology, and, therefore, can be applied in mass-application instruments including wireless networks. In this lecture we consider the application of MIS structure gas sensors for the detection of concentrations of a number of hazardous gases, which can be dangerous themselves (fluorine, hydrogen fluoride, H2S, NO2, etc.) as toxic agents or are important from ecological point of view (for example, chlorofluorocarbons, which destroy ozone layer and are responsible for green-house effect). The third class of gases like hydrogen is indicator of early stage of fire (smoldering) and is used for prevention of hazardous situation.
MIS structure sensors have a structure Si(SiC)/SiO2/solid electrolyte/Pt(Pd). Solid electrolytes, which can be used in this case are LaF3 (F- conducting) or various proton conducting materials. Recently, the possibility of the application of ion-exchange materials is also under study. This structure enables the separation of two processes responsible for gas response: electrochemical reaction on three-phase interface gas/Pt/solid electrolyte and ionosorption on the solid electrolyte/SiO2 interface. This separation of processes accelerates significantly overall process compared to traditional hydrogen MIS-structure sensors with Pd gate.