Temperature and optical characteristics of tin oxide membrane gate ISFET

The influence of temperature and optical effects on ISFET performance are i mportant. In this study, the temperature characteristics of the SnO2/Si3N4/ SiO2/Si ISFET are investigated by the zero temperature coefficient (T.C.) a djustment and the dual FET's configuration, respectively. The result show t hat a zero T.C. of the SnO2 gate ISFET can be achieved when the appropriate operation current was set. Subsequently, the T.C. of tin oxide membrane/el ectrolyte interfacecan be evaluated by the dual FET's configuration, On the other hand, due to the SnO2 gate ISFET is sensitive to the light exposure, thus in order to improve this drawback, a multi-structure ISFET's: SnO2/Al /SiO2/Si3N4/Si ISFET's have been developed, in this structure, aluminum is used as a light shield, and the tin oxide is used as a pH sensitive layer. The results show the ISFET's with aluminum as a light shield have low light sensitivity compared with ISFET's without aluminum as a light shield.