Ultralow Schottky Barriers in hBN-Encapsulated Monolayer WSe${}_2$ Tunnel Field-Effect Transistors

Abstract

To explore the potential of field-effect transistors (FETs) based on monolayers of the two-dimensional semiconducting channel(SC) for spintronics, the two most important issues are to ensure the formation of variable low resistive tunnel ferromagnetic contacts(FC), and to preserve intrinsic properties of the SC during fabrication. Large Schottky barriers lead to the formation of high resistive contacts and methods adopted to control the barriers often alter the intrinsic properties of the SC. This work aims at addressing both issues in fully encapsulated monolayer WSe${}_2$ FETs by using bi-layer h-BN as a tunnel barrier at the FC/SC interface. We investigate the electrical transport in monolayer WSe${}_2$ FETs with current-in-plane geometry that yields hole mobilities $\sim$ 38.3 $c{m}^2{V}^{-1}{s}^{-1}$ at 240 K and On/Off ratios of the order of 10${}^7$, limited by the contact regions. We have achieved ultralow effective Schottky barrier ($\sim$ 5.34 meV) with encapsulated tunneling device as opposed to a non-encapsulated device in which the barrier heights are considerably higher. These observations provide an insight into the electrical behavior of the FC/h-BN/SC/h-BN heterostructures and such control over the barrier heights opens up the possibilities for WSe${}_2$-based spintronic devices.

arXiv commentThis document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Applied Materials and Interfaces \{copyright} American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/abs/10.1021/acsami.0c01025

References in corpus (14)

• Coupled spin and valley physics in monolayers of MoS2 and other group-VI dichalcogenides
• Mobility engineering and metal-insulator transition in monolayer MoS2
• Light-emitting diodes by bandstructure engineering in van der Waals heterostructures
• Hopping Transport through Defect-induced Localized States in Molybdenum Disulfide
• Ultrasensitive and broadband MoS2 photodetector driven by ferroelectrics
• Electron Transport in Disordered Graphene Nanoribbons
• Band-Like Transport in High Mobility Unencapsulated Single-Layer MoS2 Transistors
• Field-Effect Transistors Based on Few-Layered alpha-MoTe_2
• Large current modulation in exfoliated-graphene/MoS2/metal vertical heterostructures
• Spin-orbit coupling induced valley Hall effects in transition-metal dichalcogenides
• Graphene-WS${}_2$ heterostructures for tunable spin injection and spin transport
• High conduction hopping behavior induced in transition metal dichalcogenides by percolating defect networks: toward atomically thin circuits
• Tunneling transport in a few monolayer-thick WS2/graphene heterojunction
• Bilayer h-BN Barriers for Tunneling Contacts in Fully-Encapsulated Monolayer $\mathbf{MoS}{\mathbf{e}}_2$ Field-Effect Transistors

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• Layered semiconductors integrated with polyimide thin films for high-quality valleytronic and quantum-photonic systems