Proposal for an Ion-Sensitive Floating-Gate MOSFET with Tunable Sensitivity and Memory Properties

This work proposes a new Ion-Sensitive Floating Gate MOSFET, using ultra-thin body and box (UTBB) Silicon-On-Insulator (SOI) structure, to detect charges at the front oxide/ion concentration solution interface in the range of 5.10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> and 5.10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup>. The device operates based on a floating gate charge effect for detection and retains the charge, providing a memory effect. The device’s operation and characteristics were investigated through simulations, revealing that the average electron concentration in the floating gate depends on the oxide/solution interface charge, varying from 1.10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sup> to 1.7.10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">19</sup> cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup>. Additionally, the write time and voltage have an impact on the memory window. Increasing the write times increases the memory window, from 1.42 to 2 V, for charge times from 2 to 40 seconds. The device’s sensitivity can be controlled by adjusting the write time, offering a means to detect ions in solution. Moreover, the memory window read with charges at the oxide/solution interface can be used to sense interface charges from a reference memory window without charges. Overall, the proposed device shows promise for applications in ion sensing and detection, offering tunable sensitivity and memory properties.