Study of pH Sensing Characteristics Based on TiO_2/ITO Glass with Annealing Treatment

摘要

In this study, the titanium oxide (TiO_2) thin films were deposited on ITO glass by sol-gel method. And the sensing structures were annealed at 200, 300, 400 and 500 °C for 30 min, respectively. The annealed films were further characterized by AFM. The average roughness of the annealed films were kept within 12.5-17 nm as the temperature increased form 200 °C to 500 °C. In addition, the TiCh/ITO glass structure was connected with a commercial MOSFET device, and the extended-gate field-effect transistor (EGFET) was formed and applied to as a pH sensor. The current-voltage (IDS-VDS) curves were measured with the I-V measurement system under different buffer solutions (pH=l~ll) as well as the pH response of the EGFET device was operated at constant voltage constant current (CVCC) circuit in this study. The experimental results shown that the pH sensitivity of the EGFET device were 85.57 fi A/pH and 61.26 mV/pH at annealed temperature of 200 °C. And the sensitivity changed to 66.95 jlA/pli and 53.86 mV/pH as the annealed temperature was arise to 500 °C.