Highly Sensitive Ion Detection With Graphene/Si Schottky Junction Sensors

A graphene/silicon Schottky junction-based ion-sensor with ultrahigh sensitivity for metal ions in a liquid environment is reported. High-quality single layer graphene grown in CVD system was used for device fabrication, and the sensor chip was packaged and encapsulated on a PCB with epoxy resin to meet its aquatic operating environment. Graphene's atomically thin nature and tunable fermi level enabled the device to easily detect ion concentration variations from variation in the Schottky barrier height at the graphene/silicon heterojunction interface. The junction current was observed to change exponentially with the Schottky barrier height, which offers huge advantage over commonly used field effect transistor for sensing applications.