H2, CO and high vacuum regeneration of ozone poisoned pseudo-Schottky Pd–InP based gas sensor

Abstract

This article deals with pseudo-Schottky diode Pd–InP gas sensor. Catalytic activity of such palladium layer permits to measure very low concentrations of two powerful oxidizing gases, nitrogen dioxide (NO2) and ozone (O3), constituting main urban atmospheric pollution. After many O3 submissions, degradation of gas sensor characteristics (response time, recovery time and sensitivity) appears, probably due to ozone oxidation of palladium metallization. Different treatments (H2 reduction, CO reduction and high vacuum) were then tested to avoid degradation of sensor parameters. Initial response and recovery times of this sensor can be recovered by H2 reduction and high vacuum treatment of metallization layer after exposure to ozone. Moreover, results emphasize that these treatments improve sensor sensitivity. CO reduction will permit to have reproducible measurements of low NO2 and O3 concentrations.