Electrolyte-insulator-semiconductor structure (EIS) with TiO2 thin film for Pb+ detecting

In this work Electrolyte-Insulator-Semiconductor (EIS) device has been developed for pH and lead (Pb
⁺
) measurements. As dielectric material and sensitive membrane was chosen titanium dioxide (TiO
2
) thin film. This film was obtained by sputtering, and was structurally characterized by Atomic Force Microscopy, Raman and Ellipsometry which revealed that the films present rutile and anatase crystal structure and 1.17 RMS roughness. MOS capacitors were fabricated to make the electrical characterization of TiO
2
thin films and to determine the annealing time that leads to the best thin film properties, defined by high dielectric constant value (high-k), lower charge density (Q
0
/q) and flat-band voltage (V
FB
) around −0.9V. For electrical measurement of EIS was used Capacitance x Voltage curve (CxV curve) using different pH and lead (Pb
⁺
) solutions. From the flat band voltage (V
FB
) of the CxV curves was possible to determine the sensitivity of 96mV/pH for pH measurements and sensitivity of 30mV/ppm for different lead concentration in solution measurements.