Proposal for a New Floating-Gate Ion-Sensitive FET with Tunable Sensitivity and Memory Properties

This study introduces a Floating Gate Ion-Sensitive Field Effect Transistor (FG ISFET) based on Ultra-Thin Body and Box Silicon-On-Insulator (UTBB SOI) structure, to sense charges at the front interface (between the top oxide and analyte solution) within the range of 5×1011 and 5×1012 cm−2. The device functions based on a floating gate charge effect for detection and storage the charge, enabling a memory effect. Numerical simulations were conducted to explore the device's operation and characteristics, indicating that the average electron concentration storage in the floating gate is influenced by the front interface charge ranging from 1×1017 3.7×1019 cm−3. Furthermore. The write time and voltage affect the memory window, longer write times expand the memory window from 1.42 V to 2 V for charge durations between 2 and 40 seconds. The sensitivity of the proposed device can be tuned by modifying the write time, providing a method to detect ions in solution. Additionally, the memory window, measured with charges at the oxide/analyte interface, can be utilized to sense interface charges compared to a reference memory window without charges. In summary, the proposed device exhibits significant potential for ion sensing and detection applications, featuring adjustable sensitivity, memory capabilities and resolution.