Saturation and Flow Rate Effects on the Response of a Pd/AIN/SiC Hydrogen Sensor

Abstract

AbstractA Pd/AlN/SiC device was fabricated with a 550 Å thick AlN layer in between the SiC substrate and Pd gate. At fixed flow rate, the response to Hydrogen initially increases roughly linearly with concentration, but eventually becomes saturated. The magnitude of the response as well as the saturating concentration increase with temperature. At 120° C the response saturates around 60 ppm of H2 whereas at 250° C, the onset of saturation occurs at higher ppm. The magnitude of the response also increases with the total flow rate, up to a flow rate of 250 sccm beyond which it remains constant. In the linear region, the magnitude of the response increases by a factor of 4 between 120° and 250° C, at a flow rate of 250 sccm.