Postdeposition Anneal on Structural and Sensing Characteristics of High- $\kappa$ $\hbox{Er}_{2} \hbox{TiO}_{5}$ Electrolyte–Insulator–Semiconductor pH Sensors

In this letter, we develop an electrolyte-insulator-semiconductor (EIS) device using a high- κ Er
₂
TiO
₅
sensing membrane deposited on a Si substrate through cosputtering. We used X-ray diffraction and X-ray photoelectron spectroscopy to study the structural properties of these films annealed at various temperatures. The EIS device incorporating an Er
₂
TiO
₅
sensing film annealed at 900
^°
C exhibited a higher sensitivity of 58.4 mV/pH, a lower hysteresis voltage of 4.6 mV, and a smaller drift rate of 1.2 mV/h than other annealing temperatures, presumably suggesting the formation of a well-crystallized Er
₂
TiO
₅
film and a thinner silicate layer at the oxide/Si interface.