Metal-insulator-gap-insulator-semiconductor structure for sensing devices.

We report on the use of sensing devices that have a metal-insulator-gap-insulator-semiconductor structure. We have used capacitance-voltage measurements from a metal-insulator-gap-insulator-semiconductor sensing device to characterize different pH solutions and deoxyribonucleic acid (DNA) solutions. Hysteresis in the capacitance-voltage curves results from mobile ionic charges in the solutions and the influence of changes on the sensing surface condition. As the pH decreases in the pH range of 2.7 to 7.0, the flatband voltage shift toward the negative voltage increases. The differences in the flatband voltage shift in capacitance-voltage curves are related to the mobile ionic charge density in solutions with different pH values or DNA molecules.