Elaboration and characterization of metal oxide thin films doped with different metals: Application to gas detection

Abstract

Abstract : This doctoral research focused on the development, characterization of undoped, and barium (Ba)-doped metal oxide thin films - including NiO, ZnO and ZnNiO composites - intended for gas sensing. Using the spray pyrolysis technique, the study examined the influence of deposition parameters and Ba doping on the structural, morphological, optical and electrical properties of these materials. The main objective was to optimize these films to achieve stable p-type conductivity in NiO and improve gas sensor performance. The results showed that the synthesis method produced crystalline films whose properties were modulated by precursor concentration and Ba doping. Significant changes in structural parameters, surface morphology and optical characteristics were observed for both NiO and ZnO films. The most important contribution lies in the analysis of Ba-doped ZnNiO composites, where the coexistence of ZnO and NiO phases was confirmed, and doping directly affected their optical and electrical responses. Despite these advances, challenges remain, not least the difficulty of achieving stable p-type conductivity in NiO and maintaining homogeneous film quality. Long-term stability in variable environments requires ongoing research. Future avenues include computational modeling, interface engineering, co-doping strategies, and optimization of post-deposition processing to improve the performance and commercial viability of these gas sensors.