Effects of storage conditions on ISFET performance

Ion-sensitive field-effect transistors (ISFETs) have been fabricated using low-pressure chemical-vapor-deposited (LPCVD) silicon nitride on top of silicon dioxide as a double gate dielectric. The double dielectric layer provides improved ion blocking for the gate dielectric in solution with enhanced pH sensitivity over time. Three different storage conditions were tested using the sensor at room temperature: dry storage, dry storage for three weeks followed by wet storage, and continuous wet storage. Significant differences were observed in the ISFETs´ characteristics due to the different storage conditions. An increase in pH sensitivity was observed when they were stored wet, approaching the theoretical Nernst potential at 25 degrees C.<>