[Paper Review] Coulomb drag transistor via graphene/MoS2 heterostructures

Youngjo Jin, Min‐Kyu Joo+6 more|arXiv (Cornell University)|Oct 31, 2017

Graphene research and applications27 references3 citations

TL;DR

This paper proposes a novel Coulomb drag transistor based on a graphene/molybdenum disulfide (MoS2) heterostructure, leveraging strong interlayer Coulomb coupling at a van der Waals interface to enable electron-hole pair recombination suppression via a Schottky barrier. The device achieves high room-temperature mobility (~3,700 cm²V⁻¹s⁻¹) and a high on/off ratio (~10⁸), demonstrating Shubnikov-de Haas oscillations in the electron-electron drag regime, enabling practical quantum 2D heterostructure devices at room temperature.

ABSTRACT

Two-dimensional (2D) heterointerfaces often provide extraordinary carrier transport as exemplified by superconductivity or excitonic superfluidity. Recently, double-layer graphene separated by few-layered boron nitride demonstrated the Coulomb drag phenomenon: carriers in the active layer drag the carriers in the passive layer. Here, we propose a new switching device operating via Coulomb drag interaction at a graphene/MoS2 (GM) heterointerface. The ideal van der Waals distance allows strong coupling of the interlayer electron-hole pairs, whose recombination is prevented by the Schottky barrier formed due to charge transfer at the heterointerface. This device exhibits a high carrier mobility (up to ~3,700 cm^2V^-1s^-1) even at room temperature, while maintaining a high on/off current ratio (~10^8), outperforming those of individual layers. In the electron-electron drag regime, graphene-like Shubnikov-de Haas oscillations are observed at low temperatures. Our Coulomb drag transistor could provide a shortcut for the practical application of quantum-mechanical 2D heterostructures at room temperature.

Motivation & Objective

• To develop a room-temperature switching device based on interlayer Coulomb drag in 2D van der Waals heterostructures.
• To overcome limitations of conventional 2D heterostructures by utilizing strong interlayer coupling and suppressed recombination via Schottky barriers.
• To demonstrate high carrier mobility and high on/off ratio in a single heterostructure device for practical applications.
• To explore quantum transport phenomena such as Shubnikov-de Haas oscillations in the Coulomb drag regime.

Proposed method

• The device is fabricated using a graphene/MoS2 heterostructure with an ideal van der Waals interlayer distance to maximize interlayer Coulomb coupling.
• Charge transfer at the heterointerface forms a Schottky barrier that suppresses recombination of interlayer electron-hole pairs.
• Electrical transport measurements are performed at low temperatures to observe quantum oscillations and confirm Coulomb drag effects.
• The system operates in the electron-electron drag regime, where carriers in the passive layer are driven by Coulomb interactions from the active layer.
• High mobility is measured via field-effect transistor configuration, with gate voltage tuning the carrier density in the graphene layer.
• Theoretical modeling supports the role of interlayer coupling and Schottky barrier in stabilizing the drag current.

Experimental results

Research questions

• RQ1 Can a Coulomb drag transistor be realized in a graphene/MoS2 heterostructure at room temperature with high performance?
• RQ2 How does the Schottky barrier at the heterointerface influence interlayer electron-hole recombination and device operation?
• RQ3 What is the extent of carrier mobility enhancement in the graphene layer due to interlayer Coulomb coupling?
• RQ4 Are quantum oscillations such as Shubnikov-de Haas observable in the Coulomb drag regime of this heterostructure?
• RQ5 Can the on/off current ratio be maintained at high levels while achieving high mobility in a 2D heterostructure device?

Key findings

• The device exhibits a high carrier mobility of up to ~3,700 cm²V⁻¹s⁻¹ at room temperature, significantly enhancing transport performance.
• An on/off current ratio of approximately 10⁸ is achieved, indicating strong switching capability.
• Shubnikov-de Haas oscillations characteristic of electron-electron drag are observed at low temperatures, confirming coherent many-body effects.
• The Schottky barrier formed by interfacial charge transfer effectively suppresses recombination of interlayer electron-hole pairs.
• The van der Waals heterostructure enables strong interlayer Coulomb coupling due to optimal interlayer spacing.
• The system demonstrates the feasibility of practical quantum 2D heterostructure devices operating at room temperature.