Study of TiO2 thin films for ion sensitive field effect transistor application with RF sputtering deposition

Thin films of titanium dioxide (TiO2) have been deposited on (100) silicon wafers by RF sputtering from a 99.99% pure TiO2 target, which yield film with yielded films with attractive physical and mechanical properties. Furthermore, the dielectric constant of the TiO2 thin films covers a wide range, and the films can be tested for use as protective and isolating layers. In this work, we study the sensitivity of the TiO2 films applied to the ion sensitive field effect transistor (pH-ISFET). In order to examine the properties of the surface adsorption, pH response and corrosion of the sensing material, the EIS structure is often employed. The C-V measurement is well known for the characterization of a MOS capacitance, which is also suitable for characterizing an EIS structure. After TiO2 thin films were annealed at 500degreesC in oxygen for 1 h, the sensitivities of TiO2 gate pH-ISFET and EIS devices were determined by the I-DS-V-G and C-V curves that shifted in the various pH buffer solutions. Furthermore, X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical state and composition of the titanium dioxide films. The results show that Ti4+ and O 1s states exist on the sputtered surface and atomic concentrations of both were measured.