Influence of NH3 plasma and Ti doping on pH-sensitive CeO2 electrolyte-insulator-semiconductor biosensors

Abstract

In this study, CeO2 pH-sensitive sensing membranes in electrolyte-insulator-semiconductor structures on silicon substrate were fabricated. To enhance sensing performance, the membrane underwent Ti doping and NH3 plasma treatment on the surface. To examine the effects of Ti doping and plasma treatment, multiple material properties evaluations were conducted using field-emission scanning electron microscopy, X-ray diffraction, atomic force microscopy, and secondary ion mass spectroscopy. Results indicate that Ti doping and plasma treatment can remove defects and enhance crystallization, thereby achieving improved pH-sensing performance of the membrane with high sensitivity, high linearity, low hysteresis voltage and low drift voltage. CeO2-based EIS membranes with Ti doping and NH3 plasma treatment show promise for future portable pH-sensitive biosensors.

Excellent physicochemical and sensing characteristics of a RexOy based pH sensor at low post-deposition annealing temperature

“…The flat band voltage was shifted according to the varying pH can be portrayed in eqn (2). 30 where E REF is the potential of the reference electrode, φ 0 is the surface potential between the electrolyte and the sensing surface, χ sol is the dipole potential of the solution, Φ Si denotes the work function Si, C ox signifies the oxide capacitance per unit area, Q SS is the interface charge density, Q OX is the fixed positive oxide charge. A decrease in pH or attachment of more positive charges to the Re x O y surface led the C – V curves to shift toward the more positive value of the reference voltage.…”

NH3 Plasma-Treated Magnesium Doped Zinc Oxide in Biomedical Sensors with Electrolyte–Insulator–Semiconductor (EIS) Structure for Urea and Glucose Applications

“…Additionally, the investigation also revealed that the capacitance of the EIS device subjected to NH 3 plasma treatment for 6 min was smaller compared with the capacitance of the EIS device treated for 3 min. This indicates that prolonged NH 3 plasma treatment does damage the film's surface or reduce sensitivity [31]. However, Mg 2+ ions can easily form because Mg has a low electronegativity (X = 1.31).…”

Effects of NH3 Plasma and Mg Doping on InGaZnO pH Sensing Membrane

“…Furthermore, magnesium atoms were doped into InGaZnO films and NH 3 plasma treatment was incorporated into the membrane fabrication process [ 12 , 13 ] to boost ion-sensing behavior. Based on previous studies [ 10 , 14 , 15 ], magnesium atoms can fill in vacancies and reduce dangling bonds, and NH 3 plasma treatment can include N atoms into the membrane to mitigate defects. Therefore, combination of Mg doping and NH 3 plasma treatment may effectively improve material quality and ion-sensing capability [ 13 ].…”