Structural Properties and Sensing Characteristics of YbTaO4 Sensing Membranes

Abstract

In this paper, we developed YbTaO4 sensing membranes for use in a solid-state electrolyte–insulator–semiconductor (EIS) pH sensor. Impact of rapid thermal annealing (RTA) treatment on the structural and sensing properties of the YbTaO4 sensing membranes deposited through reactive co-sputtering onto Si substrates was investigated. X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy were employed to examine the structural, morphological, and chemical features, respectively, of the YbTaO4 sensing films annealed at three RTA temperatures (700, 800 and 900 °C). The YbTaO4 EIS sensor annealed at the 800 °C exhibited a super-Nernstian response of 71.17 mV/pH within the pH range of 2–12. It also showed the lowest hysteresis voltage (<1 mV) and the lowest drift rate (0.22 mV/h) among the these RTA temperatures. Presumably, the optimal annealing temperature improved the stoichiometry of YbTaO4 film and increased its (-131)-oriented nanograin size. Figure 1