Nanostructured polyaniline films on silicon for sensitive sensing of ammonia

•Nanostructured polyaniline–silicon heterojuction has been explored as gas sensor.•Important characteristics of the above heterojuction have been established.•The proposed platform offers sensitive sensing of ammonia.•Proposed technique may be useful for the fabrication of surface conductance based as well as MEMS based ammonia sensors.

Silicon (Si)–nanopolyaniline (PAni) conducting platform has been electrochemically developed for the sensitive sensing of ammonia. The nano PAni films are formed through the assembly of nano granules of the polymer. The average height of the film is in the range of 50 nm. The electrical conductivity of the Si–PAni is influenced in the presence of ammonia. The response of this conductometric sensor is almost linear within 5–50 ppm of ammonia. The response and the recovery times are observed to be 10 and 60 s, respectively for 10 ppm of ammonia. The response time of the sensor for other concentrations (viz. 20, 30, 40, 50 and 60 ppm ammonia) is also in the range of 10 ± 2 s. However, the recovery of the sensor takes slightly longer time (70 ± 3 s) in case of higher concentrations (≥40 ppm) of ammonia.