Study of capacitive structures for amplifying the sensitivity of FET-basedchemical sensors

This paper reports on the development of ion sensitive field effect capacit ors (ISFEC) as microsensors. ISFEC/(metal/oxide/ semiconductor) field effec t transistor (MOSFET) amplifying structures are designed and studied in ord er to improve the sensitivity of field effect transistor (FET)-based chemic al sensors (CHEMFETs). Demonstration is performed through the characterisat ion Of SiO2/Si3N4 ISFEC sensors for pH measurement. Linear responses and hi gh detection sensitivities are evidenced on wide pH ranges. Theoretical and experimental studies are in agreement, clarifying dynamic phenomena, lower experimental amplification ratios and measurement drawbacks. Such amplifyi ng structures will lead to further improvements for FET-based microsensors. (C) 2001 Elsevier Science B.V. All rights reserved.