Influence of Annealing Temperature on Structural Compositions and pH Sensing Properties of Sol-Gel Derived YTi_xO_yElectroceramic Sensing Membranes

Abstract

The present study was designed to determine the effect of annealing temperature on the sol-gel synthesized YTixOy electroceramic sensing membrane on silicon substrate as an electrolyte-insulator-semiconductor (EIS) based pH sensor. We observed that the YTixOy sensing membranes after annealing at high temperatures (700, 800 and 900°C) modify the structural feature, sensing characteristic and reliability. X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy have been used to reveal the film microstructure, surface morphology and chemical composition, respectively. As compared to the other annealed samples, the YTixOy sensing membrane annealed at 800°C manifested the highest sensitivity (58.52 mV per unit of pH), lowest hysteresis voltage (2.6 mV), and lowest drift rate (0.10 mV/h). These results demonstrate that the film annealed at 800°C suppresses the formation of oxygen vacancy and intrinsic defect forming a stoichiometric YTixOy sensing film.

Capacitive Field-Effect EIS Chemical Sensors and Biosensors: A Status Report

“…It is known that the gate-insulator material in the first ISFET was SiO 2 , which is not the best pH-sensitive material, having a low sensitivity, a narrow linear pH range, a relatively high drift, and a large hysteresis (see, e.g., [9,30,31]). Therefore, other oxides, like Al 2 O 3 [32][33][34], Ta 2 O 5 [29,35,36], ZrO 2 [37], HfO 2 [38][39][40][41], CeO 2 [42], Gd 2 O 3 [43,44], Ti-doped Gd 2 O 3 [45], Lu 2 O 3 [46], Nd 2 O 3 [47], Yb 2 O 3 [48], Dy 2 TiO 5 [49], Er 2 TiO 5 [50], PbTiO 3 [51], YTi x O y [52], Tm 2 Ti 2 O 7 [53], and barium strontium titanate (BST) [54][55][56], as well as Si 3 N 4 [32,57] and nanocrystalline diamond (NCD) [58], have been proven as pH-sensitive gate insulators for EIS sensors. Some of the recent results, including the pH-sensitive material used, deposition technique, pH sensitivity, pH range, drift, and hysteresis, are summarized in Table 1.…”