Comparison of structural and sensing characteristics and PrTiO_3 sensing membrane for pH-ISFET application

摘要

In this paper, we investigated on the structural properties and sensing characteristics of Pr_2O_3 and PrTiO_3 sensing membrane deposited on Si substrates by reactive rfsputtering. 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. Compared with Pr_2O_3 sample, electrolyte-insulator-semiconductor devices with a high-k PrTiO_3 sensing film annealed at 800 C exhibit good sensing characteristics, including a high sensitivity of 56.8 mV/pH in the solutions from pH 2 to pH 12, a small drift rate of 1.77 mV/h in the pH 7 buffer solution, and a low hysteresis voltage of 2.84 mV in the pH 7→4→7→10→7. The improvement can be explained by the formation of a thinner interfacial SiO_2 and silicate layer, and the higher surface roughness.