Harmful gases, such as nitrogen oxides, carbon monoxide and hydrocarbons, cause serious atmospheric pollution; it is important to reduce the emission of these gases from automobiles and plants. For reducing particulary nitrogen oxides, a solid-state nitrogen-oxides sensor attachables to exhaust systems is urgently demanded.

Resistive-type nitrogen oxides sensors utilizing a metal oxide semiconductor are advantageous because they are compact and inexpensive.

A Sb-doped Zn₂SnO₄ thin film with spinel-type structure which was deposited by sputtering from multi-targets of constituent metals, followed by annealing at 1000°C, showed fairly good nitrogen dioxide sensing characteristics over the range from 0 to 300 ppm at 600°C. In addition, the durability of the film in high-temperature combustion exhaust was examined, and the upper limiting temperature was obtained.

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