Monitoring of HF and F2 using a field-effect sensor

Abstract A sensor for the determination of fluorine and hydrogen fluoride in gases has been developed. Lanthanum fluoride and platinum are used as the gate materials in a field-effect device with silicon in direct contact with the ionic conductor. The determination of both gases is possible at room temperature in the ppm concentration range. The response time of the sensor is of the order of some minutes. Oxygen, which can also be determined with a similar sensor system, does not interfere. The influence of thermal activation is proved to be different for the two analytes. Selectivity for HF and F 2 can be achieved because of a very high difference in the gate voltage in both gases and the influence of the on-chip activation process.