Preparation of SiC-Doped Nickel Oxide Thin Film Gas Sensors

Abstract

The influence of doping level of nickel oxide films with different amounts of SiC additives (5, 10, 15 and 20%) on structural, optical, and electrical properties is investigated. The films were prepared by pulsed-laser deposition method. XRD patterns show the polycrystalline structure for all films with tetragonal phase for nickel oxide and monoclinic phase for SiC, and no reaction between them. The surface morphology of films was analyzed and it revealed nano-size grains for samples doped with 10 and 15% SiC. The Hall effect measurements show increase the conductivity with increase the SiC ratio and transfer the type of charge carriers from n to p-type with 20% SiC. The H₂S sensing properties are influenced by the SiC ratio in the NiO films as well as the operation temperature. The NiO sensor loaded with 10% SiC is extremely sensitive to H₂S and the best operation temperature is 50°C, and exhibits fast response speed of 7 s and recovery time of 20 s for trace level (10 ppm) H₂S gas detection.