Ammonia gas sensing property of nanocrystalline Cu2S thin films

Abstract

Nanocrystalline semiconducting thin films of copper sulphide (Cu₂S) were deposited by novel chemical route using aqueous solution of 0.1 M copper chloride, 0.05 M thiourea, complexing agent 10% aqueous ammonia (NH₃) and hydrazine hydrate. The characterization and gas sensitivity of as deposited Cu₂S thin film sensor have been investigated. The as deposited Cu₂S thin films were observed to be very sensitive for NH₃ gas at room temperature. Upon exposure of NH₃ gas the Cu₂S sensors lead to decrease in resistance which is attributed due to inter-conversion of Cu(I) and Cu(II) charge states. The response to ammonia gas by Cu₂S thin film is detected at 200 to 500 ppm concentration in air. The maximum sensitivity (19.78%) for ammonia gas by Cu₂S sensor was found at 500 ppm gas concentration. The quick response (~60 s) and fast recovery (~90 s) are the main features of these sensors. The effects of gas concentrations on the gas sensing performance of the Cu₂S sensor have been studied and discussed