Temperature influence, semiconductor sensors

The influence of other active components, such as 1, OH, H on a semiconductor sensor, with other conditions being the same, is comparable with the influence of atomic oxygen [50]. Contribution of N and OH is proportional to their relative contents (compared to that of atomic oxygen) in the atmosphere and may become essential at altitudes lower than 60 - 70 km. The use of selective detectors excludes the influence of atomic hydrogen. Studies of adsorption of water vapours on ZnO films [50] show that their influence is negligibly small at the film temperatures below 100°C. Variations of electric conductivity of the films under the influence of water vapours and of an atomic oxygen are comparable at the ratio of their concentrations [H20]/[0] = 10" . 

The influence of temperature on the selectivity of a sensor depends on the fact that each gas has its own characteristic temperature a temperature at which the reversible relationship between gas concentration and the concentration of electrons at the semiconductor surface (and therefore the conductance) reaches a maximum [110]. Working temperatures for Sn02-based sensors usually lie between 200 °C and 450 °C depending on the application. 

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