Influence of the substrate on the overall sensor impedance of planar H₂ sensors involving TiO₂–SnO₂ interfaces

Abstract. To date, very little has been written about the influence of the substrate layer on the overall sensor impedance of single- and multilayer planar sensors (e.g., metal-oxide sensors). However, the substrate is an elementary part of the sensor element. Through the selection of a substrate, the sensor performance can be manipulated. The current contribution reports on the substrate influence in multilayer metal-oxide chemical sensors. Measurements of the impedance are used to discuss the sensor performance with quartz substrates, (laboratory) glass substrates and substrates covered by silicon-dioxide insulating layers. Numerical experiments based on previous measurement results show that inexpensive glass substrates contribute up to 97% to the overall sensor responses. With an isolating layer of 200 nm SiO₂, the glass substrate contribution is reduced to about 25%.