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Super-Nernstian ion sensitive field-effect transistor exploiting charge screening in WSe2/MoS2 heterostructure

Sanjay, S and Hossain, M and Rao, A and Bhat, N (2021) Super-Nernstian ion sensitive field-effect transistor exploiting charge screening in WSe2/MoS2 heterostructure. In: npj 2D Materials and Applications, 5 (1).

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Official URL: https://doi.org/10.1038/s41699-021-00273-6

Abstract

Ion-sensitive field-effect transistors (ISFETs) have gained a lot of attention in recent times as compact, low-cost biosensors with fast response time and label-free detection. Dual gate ISFETs have been shown to enhance detection sensitivity beyond the Nernst limit of 59 mV pH�1 when the back gate dielectric is much thicker than the top dielectric. However, the thicker back-dielectric limits its application for ultrascaled point-of-care devices. In this work, we introduce and demonstrate a pH sensor, with WSe2(top)/MoS2(bottom) heterostructure based double gated ISFET. The proposed device is capable of surpassing the Nernst detection limit and uses thin high-k hafnium oxide as the gate oxide. The 2D atomic layered structure, combined with nanometer-thick top and bottom oxides, offers excellent scalability and linear response with a maximum sensitivity of 362 mV pH�1. We have also used technology computer-aided (TCAD) simulations to elucidate the underlying physics, namely back gate electric field screening through channel and interface charges due to the heterointerface. The proposed mechanism is independent of the dielectric thickness that makes miniaturization of these devices easier. We also demonstrate super-Nernstian behavior with the flipped MoS2(top)/WSe2(bottom) heterostructure ISFET. The results open up a new pathway of 2D heterostructure engineering as an excellent option for enhancing ISFET sensitivity beyond the Nernst limit, for the next-generation of label-free biosensors for single-molecular detection and point-of-care diagnostics. © 2021, The Author(s).

Item Type: Journal Article
Publication: npj 2D Materials and Applications
Publisher: Nature Research
Additional Information: The copyright for this article belongs to the Author.
Keywords: Biosensors; Electric fields; Gate dielectrics; High-k dielectric; Ion sensitive field effect transistors; Layered semiconductors; Logic gates; Molybdenum compounds; pH sensors; Selenium compounds, Back gates; Charge screening; Detection sensitivity; Dual gates; Fast response time; Ion-sensitive field effect transistors; ITS applications; Label-free detection; Low-cost biosensors; Time-free, Hafnium oxides
Department/Centre: Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited: 12 Jan 2022 05:49
Last Modified: 12 Jan 2022 05:49
URI: http://eprints.iisc.ac.in/id/eprint/70938

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