Carbon Vacancy Assisted Contact Resistance Engineering in Graphene FETs

Kumar, J and Meersha, A and Variar, HB and Mishra, A and Shrivastava, M (2022) Carbon Vacancy Assisted Contact Resistance Engineering in Graphene FETs. In: IEEE Transactions on Electron Devices, 69 (4). pp. 2066-2073.

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Abstract

Despite various remarkable properties, the state of the arts of graphene devices are still not up to the mark due to their high contact resistance. The contact resistance milestone has not been achieved yet, probably due to ambiguity in understanding graphene-metal contact properties. In this work, we did a systematic investigation of palladium-graphene contact properties using a density functional theory (DFT) and various process-based experimental approaches. Our study reveals significant interaction of palladium (Pd) with graphene. Their orbitals overlap leads to potential barrier lowering at the interface, which can be reduced further by bringing graphene closer to the bulk Pd using carbon vacancy engineering at the contacts. Thus, the carbon vacancy-assisted barrier modulation reduces contact resistance by increasing carrier transmission probabilities at the interface. The theoretical findings have been emulated experimentally by carbon vacancy engineering at the graphene field-effect transistors (FETs). Different contact-engineered graphene devices with Pd contacts show significant contact resistance reduction, measuring as low as ~78Ω·μm at room temperature. The contact resistance shows a 'V' shape curve as a function of defect density. Also, the optimum contact resistance achieved is significantly lower than their pristine counterpart, as predicted by the theoretical estimates. Due to contact engineering, ION improves by ~6×, transconductance by ~8×, and device mobilities by ~6× in the device FETs. These investigations and understanding can help to boost the performance of graphene FETs, especially for high-frequency RF applications.

Item Type:	Journal Article
Publication:	IEEE Transactions on Electron Devices
Publisher:	Institute of Electrical and Electronics Engineers Inc.
Additional Information:	The copyright for this article belongs to the Institute of Electrical and Electronics Engineers Inc.
Keywords:	Carrier communication; Contact resistance; Density functional theory; Field effect transistors; Graphene; Graphene transistors; Modulation, Carbon vacancy; Contact properties; Density functional theory; Density-functional-theory; Field-effect transistor; Graphene field-effect transistors; Property; Quantumatk; Vacancy engineering; Vacancy., Palladium
Department/Centre:	Division of Electrical Sciences > Electronic Systems Engineering (Formerly Centre for Electronic Design & Technology) Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	16 Jun 2022 10:29
Last Modified:	16 Jun 2022 10:29
URI:	https://eprints.iisc.ac.in/id/eprint/73708

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