Increasing the selectivity of Pt-gate SiC field effect gas sensors by dynamic temperature modulation

Abstract

Based on a diode coupled silicon carbide field effect transistor with platinum as catalytic gate material, the influence of dynamic temperature modulation on the selectivity of GasFETs has been investigated. This operating mode, studied intensively for semiconductor gas sensors, is applied for the first time with gas sensors based on the field effect. A suitable T-cycle for detection of typical exhaust gases (CO, NO, C 3 H 6 , H 2 , NH 3 ) was developed and combined with appropriate signal processing based on multivariate statistics, e.g. linear discriminant analysis (LDA). Measurements have proven that several gases can be discriminated based on T-cycle data. Furthermore, quantitative determination of gases is also possible. In addition to varying the measurement conditions (e.g. background oxygen) experiments regarding stability and reproducibility were also carried out. Based on these preliminary studies the performance of field effect gas sensors can be enhanced considerably by T-cycling.