MoS2 Field-Effect Transistor Performance Enhancement by Contact Doping and Defect Passivation via Fluorine Ions and Its Cyclic Field-Assisted Activation

Rai, AK and Shah, AA and Kumar, J and Chattaraj, S and Dar, AB and Patbhaje, U and Shrivastava, M (2024) MoS2 Field-Effect Transistor Performance Enhancement by Contact Doping and Defect Passivation via Fluorine Ions and Its Cyclic Field-Assisted Activation. In: ACS Nano, 18 (8). pp. 6215-6228.

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Abstract

MoS2-based field-effect transistors (FETs) and, in general, transition metal dichalcogenide channels are fundamentally limited by high contact resistance (RC) and intrinsic defects, which results in low drive current and lower carrier mobilities, respectively. This work addresses these issues using a technique based on CF4 plasma treatment in the contacts and further cyclic field-assisted drift and activation of the fluorine ions (F-), which get introduced into the contact region during the CF4 plasma treatment. The F- ions are activated using cyclic pulses applied across the source-drain (S/D) contacts, which leads to their migration to the contact edges via the channel. Further, using ab initio molecular dynamics and density functional theory simulations, these F- ions are found to bond at sulfur (S) vacancies, resulting in their passivation and n-type doping in the channel and near the S/D contacts. An increase in doping results in the narrowing of the Schottky barrier width and a reduction in RC by �90. Additionally, the passivation of S vacancies in the channel enhances the mobility of the FET by �150. The CF4 plasma treatment in contacts and further cyclic field-assisted activation of F- ions resulted in an ON-current (ION) improvement by �90 and �480 for exfoliated and CVD-grown MoS2, respectively. Moreover, this improvement in ION has been achieved without any deterioration in the ION/IOFF, which was found to be >7-8 orders. © 2024 American Chemical Society.

Item Type:	Journal Article
Publication:	ACS Nano
Publisher:	American Chemical Society
Additional Information:	The copyright for this article belongs to the American Chemical Society.
Keywords:	Chemical activation; Defects; Density functional theory; Deterioration; Field effect transistors; Fluorine; Layered semiconductors; Molecular dynamics; Molybdenum compounds; Passivation; Plasma applications; Schottky barrier diodes; Sulfur; Transition metals, Contact resistance improvement; Defect passivation; DFT; Field-effect transistor; MoS2 field-effect transistor; Plasma contact doping; Plasma treatment; Sulfur vacancies; Sulphur vacancy defect passivation; Vacancy Defects, Contact resistance, fluoride ion; sulfur; transition element, ab initio calculation; article; controlled study; density functional theory; field effect transistor; molecular dynamics; nonhuman; plasma; simulation
Department/Centre:	Division of Electrical Sciences > Electronic Systems Engineering (Formerly Centre for Electronic Design & Technology)
Date Deposited:	10 Apr 2024 05:21
Last Modified:	10 Apr 2024 05:21
URI:	https://eprints.iisc.ac.in/id/eprint/84677

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