Enhancement of NH₃ Gas Sensing Properties of NiO-Based Thin Films Deposited by DC Reactive Magnetron Sputtering

We have investigated the gas sensing characteristics of DC reactive magnetron sputtered NiO; NiO–Cu and NiO–Ag composite thin films on Corning 7059 glass substrates. The as-deposited films were annealed and studied the structural, morphological and electrical properties. Morphological studies indicated that the grain size and roughness were increased with annealing temperature. From the electrical measurements it was observed that the resistivity of the films decreased with the annealing temperature and favours to increase the sensitivity. The sensor studies revealed that even at lower gas concentrations and operating temperatures, NiO–Cu and NiO–Ag composite films sensitivity was high compared to NiO films. However, compared to NiO–Cu films, NiO–Ag films sensitivity was high due to high catalytic activity of Ag metal.