Theoretical analysis of acoustoelectrical sensitivity in SAW gas sensors

摘要

The theoretical studies on acoustoelectrical (AE) sensitivity in SAW gas sensors are presented. The analysis was based on normalized parameter ξ=σ_s/v0C_s (where: σ_s - is the film's electrical surface conductivity, v0- SAW velocity, C_s - sum of the substrate's and environment's electrical permittivities) which determines the value of AE sensitivity. The electrical surface conductivities in the bi-layer structure are correlated by the σ_(s1)= x σ_(s2) dependence. The investigations revealed that for single and bi-layer sensor structures the maximum value of AE sensitivity is obtained for ξ_(max)= ～0.6. For bi-layer structures this sensitivity is lower. However we also found the positions of the maximum values in a function of x parameter dependent on different values of normalized conductivity of the second film.