GaAs and GaN based SAW chemical sensors: acoustic part design and technology

In this paper, we present the design considerations and the technology process of SAW (surface acoustic wave) chemical sensors based either on GaAs or GaN structures. These sensors can be used for identifying environmental contaminants and chemical or biological agents in large applications scale; in this study, we aimed at the measurement of low concentrations of gaseous mercury. We describe the design of the acoustic part of the sensor including the structure for the generation and reception of the surface acoustic wave and the chemoselective coating made of gold. We show the technology process that achieves the device operating at the frequency of 250 MHz. Finally we present some preliminary results obtained from the device