Development of an ammonia gas sensor

Copper (I) bromide (CuBr) thin films for ammonia detection are prepared by two different techniques: (1) magnetron sputtering and (2) chemical or electrochemical oxidation of copper in presence of bromine ions. The microstructure of the films is related to these processes. The electrical properties of these films are studied and the temperature dependence of the bulk conductivity is in agreement with previous work on polycrystalline CuBr. After a preliminary strong exposure to ammonia gas, ammonia adsorption on films leads to a reversible decrease of conductivity. This effect is used to design a selective and sensitive ammonia gas sensor operating at ambient temperature. The sensitivity and the response time are related to the film preparation.

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