Hydrogen gas sensing performance of low partial oxygen-mediated nanostructured zinc oxide thin film

In this work, an innovative design was presented to fabricate ZnO nanostructured thin film-based sensor by thermal oxidation at low values of oxygen partial pressure using a buffer gas mixture of H₂ and H₂O at different operating temperatures. Microstructural observations of the as-fabricated films prepared at different values of oxygen partial pressure showed significantly improved surface roughness and variations in porosity with reference to those obtained by thermal oxidation of sputtered Zn films in air and ZnO prepared by DC reactive sputtering followed by heated in argon. In low operating temperatures of oxygen partial pressure, ZnO nanostructures possessed larger grain sizes and higher porosity. ZnO film prepared by oxidization of sputtered Zn in low oxygen partial pressure possessed more oxygen vacancies that lead to the formation of more active sites to target gas and to be efficient gas sensor. As-fabricated ZnO nanostructures were characterized to be a platform for H₂ gas sensing. ZnO nanostructured films with substantially improved surface roughness and porosity were found to show better gas sensing performance toward low levels of H₂ (75–1200 ppm). This work paves a possibility for developing new porous metal oxides sensors with high computability and good repeatability toward different gases.