Carbon-palladium films as gas sensors (hydrogen, ammonia, methane)

Abstract

In this paper we present the results of the resistances changes of carbon-palladium films under the influences of gas like hydrogen, ammonia and methane. Our research has shown that carbon-palladium films (C-Pd films) according to the form and the structure in which they appear, they can respond to a variety of gases. The C-Pd film obtained by Physical Vapor Deposition (PVD) method is sensitive to hydrogen and do not respond to the ammonia. Thermal modification of the C-Pd film in Chemical Vapor Deposition (CVD) process affects the morphology of the film, increases its resistance and it causes that this film begins to react to the ammonia. This change causes that this film stops responding on hydrogen. Film sensitive to methane was obtained by changing the technology conditions of the PVD process. The reaction of C-Pd film on the hydrogen and the ammonia is increase resistance, while film sensitive to methane reacts by decrease of initial resistance value. In both cases, the changes are reversible after cleaning by air atmosphere. Different varieties of C-Pd films can be used to build selective sensors for hydrogen, ammonia and methane.