A silicon-based SAW chemical sensor for NO 2 by applying a silicon nitride passivation layer

Abstract

This paper deals with the application of silicon nitride as a passivation layer on top of a dual delay-line SiSiO 2ZnO surface acoustic wave (SAW) device. The SiSiO 2ZnOnitride system is studied as a sensor for NO 2 employing copper phthalocyanine as the chemical interface. The effect of passivation on the response of the reference delay-line is found to be positive, i.e., a more passive reference delay-line is obtained. With respect to the measuring delay-line, it is found that the sensitivity becomes smaller while the selectivity is also affected in a negative way. Work is in progress to deal with a compromise: a passivated reference delay-line and a non-passivated measuring delay-line.