Characterization of porous nickel oxide base hydrogen gas sensor

Porous nickel oxide (NiO) thin films with different thicknesses were grown on alkali-free glass substrates by sol-gel method. Crystallinity and surface morphology of NiO thin films as a function of thickness were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The hydrogen gas sensing was measured to investigate the effect of thickness on the gas sensing property of thin film. Low thickness samples showed better gas sensing behavior. This behavior can be attributed to higher surface to volume ratio. This study demonstrated the importance of the thickness and porosity of the thin film for gas sensing applications and it showed that by increasing the thickness and decreasing the porosity in the film, the sensitivity of the thin film decreased significantly.