Hydrogen sensing by NKN thin film with high dielectric constant and ferroelectric property

Hydrogen sensing properties of sodium potassium niobate NaxKyNbOz (NKN) thin films were studied. The NKN thin films were prepared by reactive rf magnetron sputtering. NKN is a ferroelectric material with high dielectric constant. The polarization increases in hydrogen ambient and decreases in oxygen ambient. The conductivity of the NKN film in hydrogen ambient is higher than in oxygen ambient, and these changes are reversible. The threshold voltage of the current-voltage (I-V) characteristics depends on the hydrogen concentration, and a large response of 3.3 V was obtained.