Sputtered titanium dioxide thin film for Extended-Gate FET sensor application

Abstract

This paper presents an investigation on sputtered titanium dioxide (TiO2) thin film for application in the Extended-Gate Field Effect Transistor (EGFET) sensor application for pH detection. The TiO2 thin film was fabricated on conductive indium-tin oxide (ITO) covered glass by using RF Sputtering method. An EGFET proof-of-concept setup was constructed using a commercial FET as the transducer and the TiO2/ITO structure was used for the extended gate. The sensor measurement was taken using semiconductor device parametric analyzer, constant-current constant-voltage biasing interfacing circuit and data logger to obtain the sensitivity and the characteristics for output voltage with respect to time. TiO2 thin film on ITO glass as the sensing membrane was compared with a bare ITO glass substrate for the extended gate. The TiO2/ITO glass exhibited the sensitivity of 42.1 mV/pH and good linearity of 0.9997 in the sensing range pH4, pH7 and pH10 which was better than the bare ITO glass sensitivity of 31.3 mV/pH and the linearity of 0.9868.