[paper] Ion-Sensitive FET Memory

Henrique Lanfredi Carvalho, Pedro Henrique Duarte, Ricardo Cardoso Rangel 

and Joao Antonio Martino

“Effect of gate capacitance ratio on ion-sensitive FET memory”

Solid-State Electronics (2026) Art. no. 109350.

doi: 10.1016/j.sse.2026.109350

* LSI/PSI/USP, University of Sao Paulo, Sao Paulo, Brazil

Abstract: This paper introduces the ISFET Memory device, which combines nonvolatile memory capabilities with the traditional ISFET functionality for pH sensing applications. The device’s performance is evaluated in both writing and erasing modes, with particular emphasis on how adjusting the gate capacitance ratio (GCR) influences the operating voltages and sensitivity. Results show that optimizing the GCR to 0.43 significantly reduces the voltages required for writing and erasing operations, while also enhancing sensitivity across a broader pH range. The device achieves maximum sensitivities of 1609 mV/pH in the writing state and 940 mV/pH in the erasing state, far exceeding the ideal ISFET sensitivity of 58.2 mV/pH. Furthermore, the device demonstrates adaptability to different pH ranges: the writing mode is better suited for pH values from 2 to 10, whereas the erasing mode is more effective for the remaining pH range.

Fig: Cross section of ISFET Memory (a) and with optimized structure (b)

Acknowledgment: The authors acknowledge CNPq, CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brazil - Finance Code 001) and São Paulo Research Foundation - FAPESP (under grant #2020/04867-2) for the financial support.

[+] This article is part of a special issue entitled: ‘EuroSOI-ULIS 2025’ published in Solid State Electronics.

[paper] Compact Modeling of pH-Sensitive FETs Based on 2D Semiconductors

Tarek El Grour, Francisco Pasadas, Alberto Medina-Rull, Montassar Najari, Enrique G. Marin, Alejandro Toral-Lopez, Francisco G. Ruiz, Andrés Godoy, David Jiménez and Lassaad El-Mir

Compact Modeling of pH-Sensitive FETs Based on Two-Dimensional Semiconductors

arXiv:2109.06585 [physics.app-ph; submitted on 14 Sep 2021]

DOI: 10.1109/TED.2021.3112407

   

LAPHYMNE Laboratory, Gabes University, Gabes, Tunisia

PEARL Laboratory, Departamento de Electrónica y Tecnología de Computadores, Universidad de Granada, Spain

The Innovation and Entrepreneurship Centre, Jazan University, Jazan, Saudi Arabia.

Departament d’Enginyeria Electrònica, Escola d’Enginyeria, Universitat Autònoma de Barcelona, Spain

Abstract: We present a physics-based circuit-compatible model for pH-sensitive field-effect transistors based on two-dimensional (2D) materials. The electrostatics along the electrolyte-gated 2D-semiconductor stack is treated by solving the Poisson equation including the Site-Binding model and the Gouy-Chapman-Stern approach, while the carrier transport is described by the drift-diffusion theory. The proposed model is provided in an analytical form and then implemented in Verilog-A, making it compatible with standard technology computer-aided design tools employed for circuit simulation. The model is benchmarked against two experimental transition-metal-dichalcogenide (MoS2 and ReS2) based ion sensors, showing excellent agreement when predicting the drain current, threshold voltage shift, and current/voltage sensitivity measurements for different pH concentrations.

Fig: a) Schematic depiction of a 2D-ISFET b) its quivalent capacitive circuit

Acknowledgments: This work is supported in part by the Spanish Government under the projects TEC2017-89955-P, RTI2018-097876-B-C21 and PID2020-116518GB-I00 (MCIU/AEI/FEDER, UE); the FEDER/Junta de Andalucía under project BRNM-375-UGR18; EC under Horizon 2020 projects WASP No. 825213 and GrapheneCore3 No. 881603. E.G. Marin gratefully acknowledges Juan de la Cierva Incorporación IJCI-2017-32297. A. Toral-Lopez acknowledges the FPU program (FPU16/04043). F. Pasadas acknowledges funding from PAIDI 2020 and Andalusian ESF OP 2014-2020 (20804). F. Pasadas and D. Jiménez also acknowledge the partial funding from the ERDF allocated to the Programa Operatiu FEDER de Catalunya 2014-2020, with the support of the Secretaria d’Universitats i Recerca of the Departament d’Empresa i Coneixement of the Generalitat de Catalunya for emerging technology clusters to carry out valorization and transfer of research results. Reference of the GraphCAT project: 001-P-001702.