Abstract
Recently, extended gate field effect transistor (EGFET) had been studied for pH meter or biosensor. In this study, the differences between EGFETs by NMOS and by PMOS were introduced. And, with the ion-sense membrane, AgIn5S8 thin films coated on ITO glass substrates by hydrothermal method, the ions-sensitivities were extracted by linear mode and by saturation mode in different concentration solutions of pH/p[Cu2+]/p[Pb2+]. The results show the sulfide film is sensitive to these kinds of ions. The ion sensitivities on membrane surface are 50.7mV/pH, 23.9mV/p[Cu2+], and 95.9mV/p[Pb2+] in NMOS-EGFET under applied bias-voltage 2.5V at reference electrode with saturation mode extraction. The membranes were also analyzed by electron spectroscopy for chemical analysis (ESCA), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. The analysis also shows good crystallinity of AgIn5S8 thin film.