Structural properties and sensing characteristics of Y2O3 sensing membrane for pH-ISFET

The structural properties and sensing characteristics of Y2O3 sensing membrane were deposited on silicon substrates by reactive rf sputtering. The structural and morphological features of these films with annealing at various temperatures were studied by X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy. It was found that Y2O3 sensing dielectrics annealed at 800 °C exhibit a high sensitivity of 56.09 mV/pH in the solutions from pH 2 to pH 12, a low hysteresis voltage of 13.6 mV in the pH 7 → 4 → 7 → 10 → 7, and a small drift rate of 1.24 mV/h in the pH 7 buffer solution. This annealing condition is suggested for the reduction of the interfacial SiO2 and silicate formation, and the small surface roughness due to the well-crystallized Y2O3 structure.