Fabrication of Organic Monolayer Modified Ion-Sensitive Field Effect Transistors with High Chemical Durability

Fabrication of ion-sensitive field effect transistor (FET) with modified SiO₂ gate by various organosilane monolayers was investigated. By precise control of the fabrication processes, the FETs modified with various functional monolayers were successfully formed on the same substrate. Each modified device indicates typical transistor property with a good stability in aqueous solution. The transistor with amino monolayer modified gate showed good pH sensitivity of 58 mV/pH, whereas the profiles of transistor with the perfluoro-alkyl monolayer modified gate kept constant in any pH solutions. These monolayer-modified devices are expected to be applied as an ion-sensitive and a reference electrode for sensing devices in the solution.