Structural properties and sensing characteristics of high-k Ho2O3 sensing film-based electrolyte–insulator–semiconductor

In this study, we report a Ho2O3 electrolyte–insulator–semiconductor (EIS) device films deposited on Si substrates through reactive sputtering. The effect of thermal annealing (700, 800, and 900 °C) on the structural and surface properties of Ho2O3 sensing film was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy. We found that the EIS device with a Ho2O3 sensing film annealed at 800 °C exhibited a higher sensitivity of ∼57 mV/pH, a lower hysteresis voltage of 2.68 mV, and a smaller drift rate of 2.83 mV h−1 compared to those at other annealing conditions. This improvement can be attributed to the well-crystallized Ho2O3 structure and the large surface roughness.

► We report the structural properties and sensing characteristics of Ho2O3 sensing membranes deposited on Si substrates by reactive sputtering.
► We applied X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy to study the structural and morphological features of these films after they had been subjected to annealing at various temperatures (700 ̊C, 800 ̊C, and 900 ̊C).
► The Ho2O3 electrolyte–insulator–semiconductor device annealed at 800 ̊C exhibited a higher sensitivity, a lower hysteresis voltage, and a smaller drift rate than other annealing temperatures.