Highly sensitive suspended-gate ion sensitive transistor for the detection of pH

F. Bendriaa; F. Le Bihan; A. C. Salaun; T. Mohammed-Brahim; O. Bonnaud

doi:10.1117/12.607540

1 July 2005 Highly sensitive suspended-gate ion sensitive transistor for the detection of pH

F. Bendriaa, F. Le Bihan, A. C. Salaun, T. Mohammed-Brahim, O. Bonnaud

Proceedings Volume 5836, Smart Sensors, Actuators, and MEMS II; (2005) https://doi.org/10.1117/12.607540
Event: Microtechnologies for the New Millennium 2005, 2005, Sevilla, Spain

Abstract

This paper presents a new device for the pH detection. It is based on a suspended polysilicon gate field effect transistor (SGFET). The sensitive layer is made of silicon nitride as for ISFET technology. The suspended bridge, used as gate electrode, is formed with doped polysilicon covered with silicon nitride layers for electrical insulation. The layers are deposited by Low Pressure Chemical Vapor Deposition (LPCVD). Surface micro-technology allows to obtain a small height (0.5μm) suspended-bridge. In this case, the solution penetrates under the gate. The high field effect in the gap between the gate and the channel is enough to change the charges distribution. Very high pH sensitivity, greater than 200 mV/pH, is found with this new structure and it is much higher than the usual Nernstian sensitivity of ISFETs. The device concept, electrical characteristics, and the effect of the thickness of the gap between the bridge and the sensitive layer on the pH sensitivity are discussed in this study.

Citation Download Citation

F. Bendriaa, F. Le Bihan, A. C. Salaun, T. Mohammed-Brahim, and O. Bonnaud "Highly sensitive suspended-gate ion sensitive transistor for the detection of pH", Proc. SPIE 5836, Smart Sensors, Actuators, and MEMS II, (1 July 2005); https://doi.org/10.1117/12.607540

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