an experimental investigation of the parameters involved in determination of the transient response of a resistive gas sensor

gas sensitive metal oxide layers used in fabrication of resistive gas sensors are prepared by different deposition techniques. the technical data reported on some basic and practically important specifications of these devices, although fabricated based on the same gas sensitive oxide, are anomalously different. the influence of the fabrication technique used for the deposition of the gas sensitive layer on determination of the significant specifications of the transient response of a resistive gas sensor is experimentally investigated for the first time. zno and sno2 layers were prepared by lpcvd, pvd, epd and powder pressing techniques. prototype gas sensors based on these layers were fabricated. the transient responses of these devices to a step change in the composition of the surrounding atmosphere were recorded and compared. it was shown that the thickness, porosity and pore micro-structure of the gas sensitive layer are the most effective parameters in determination of the transient response. the relationship between these parameters and the temporal variation of the electrical conductivity of the gas sensitive layer was qualitatively analyzed. oxide layers of higher porosity resulted in gas sensors of faster response, but response time increased with the thickness of these gas sensitive layers. the sensors produced by epd technique demonstrated the fastest responses while those produced by cvd were the slowest among the samples investigated.