The room temperature ammonia sensor based on improved CuxS-micro-porous-Si structure

Ammonia sensitive structures based on CuxS film and micro-porous Si layer are produced and investigated. Resistance response to ammonia is measured in air at ambient temperatures 290-300 K and at higher ones with special heating up to 350 K. Detectable amount is from 2 ppm to few percents of ammonia in air at the ambient temperatures. The response signal increases linearly with an increase of the amount up to 100 ppm. The response signal is independent on the operation temperature < 320 K. The resistance response decreases if the relative humidity increases from 18 to 100%. Surface chemical composition and morphology of the sensitive structures are analysed. High sensitivity of the sensors is related with specific morphology of the CuxS films on the micro-porous Si. The sensitivity mechanism is related with a dependence of the hole conductance on the gas-surface interaction in the CuxS films. (C) 2001 Elsevier Science B.V. Ail rights reserved.