Negative Capacitance Ion-Sensitive Field-Effect Transistors with improved current sensitivity

TL;DR

This paper introduces a negative capacitance approach in ion-sensitive FETs, significantly enhancing current sensitivity and steepness of transfer characteristics, thus improving pH sensing performance.

Contribution

The study demonstrates experimentally that integrating a negative capacitor reduces subthreshold slope and doubles current efficiency in ISFETs, leading to a 78% increase in pH sensitivity.

Findings

Reduced subthreshold slope by 44%

More than twofold increase in current efficiency

78% improvement in pH sensitivity

Abstract

Ion-Sensitive Field-Effect Transistors (ISFETs) form a wide-spread technology for sensing, thanks to their label-free detection and intrinsic CMOS compatibility. Their current sensitivity, {\Delta}ID/ID, for a given {\Delta}pH, however, is limited by the thermionic limit for the Subthreshold Slope (SS) of Metal-Oxide-Semiconductor Field-Effect Transistors(MOSFET) and by the Nernst limit. Obtaining ISFETs with a steep slope transfer characteristics is extremely challenging. In this paper we combine the merits of traditional ISFETs with the performance boosts offered by the insertion of a Negative Capacitor in series with the Gate contact. In the proposed tests with NC PZT capacitors, we demonstrate experimentally a reduction of the SS by 44%, combined with a current efficiency improvement of more than two times. As a consequence of the steeper SS, the current sensitivity to pH is improved by 78%.