Noise analysis of MoTe₂-based dual-cavity MOSFET as a pH sensor

Abstract

Field Effect Transistor (FET) pH sensors are being studied for a long time due to their low cost, sound sensitivity, and high operational speed. In recent times, Transition Metal Dichalcogenides (TMD) materials like MoTe2, MoS2, etc., have emerged as promising channel materials for energy-efficient electronic devices. TMD-based sensors show excellent results due to the high surface area-volume ratio and better bio-specific interaction. This paper proposes and analyses a MoTe2 channel-based dual-cavity accumulation MOSFET as a pH sensor. For a comprehensive study, a pH-FET noise model has been considered to investigate the amount of noise associated with the proposed FET under various ionic concentrations and device dimensions. The electrolytic semiconductor has been modeled based on ion dynamics for the simulation study. Site-Binding Model has been incorporated to capture the surface charge density fluctuation at the interface of electrolyte and gate-oxide for different pH values. The effect of gate length scaling on the device performance is studied to comprehend its scalability. With this MoTe2-based dual-cavity accumulation MOSFET sensor, a peak threshold sensitivity of 77 mV/pH has been obtained. To provide a comparative performance analysis of the proposed work, a benchmarking figure is included in the manuscript and a detailed fabrication methodology has also been presented. All simulations are done with an experimentally calibrated setup in SILVACO TCAD.