pH Sensing of Ba[sub 0.7]Sr[sub 0.3]TiO[sub 3]∕SiO[sub 2] Film for Metal-Oxide-Semiconductor and Ion-Sensitive Field-Effect Transistor Devices

The -sensing behaviors of barium strontium titanate (BST) ultrathin films are reported. The sputtering technique was used to prepare the ferroelectric structure. To obtain better electrical characteristics for the BST membrane, we characterized electrical properties of the thin film for the gate oxides in the metal-oxide-semiconductor devices under different deposition times of 10, 20, and using high frequency capacitance-voltage and current-voltage measurements. The pH-sensing properties of the stack layers were also investigated using capacitance-voltage measurements on the electrolyte/insulator/semiconductor. The results show that BST ultrathin film still exhibits linear pH sensitivities of approximately ranging from pH 1 to 11. Besides, the drift rate and temperature dependence of the measured pH sensitivity has also been represented.