Chemically sensitive jfet transducer devices utilizing a blocking

Abstract

A chemically sensitive junction field effect transistor transducer capable of selectively detecting and measuring chemical properties of substances to which the transducer is exposed. The transducer includes a substrate material, a semiconductor layer having a doping polarity laid over the surface of the substrate, a 'source' contact connected to one part of the semiconductor layer, a 'drain' contact connected to another part, and a chemically sensitive blocking interface gate structure overlying the upper surface of that portion of the semiconductor layer between the source and drain contacts. The gate structure is adapted to interact with selected chemical substances in the substance being tested and to produce an electric field in relation to the presence, concentration, or activity thereof. This electric field, in turn, causes a modulation of the depletion region in the semiconductor layer that affects the conductivity thereof, and hence the amount of source-drain current that can flow through the transducer. The gate structure also serves as a blocking interface and prevents current from flowing through the gate structure. The chemically sensitive blocking interface gate structure may include numerous configurations and materials adapted for sensing various chemical or biochemical properties.