Ultrahigh Anisotropic Transport Properties of Black Phosphorus Field Effect Transistors Realized by Edge Contact

Lee, Myeong-jin; Ali, Nasir; Watanabe, Kenji; Taniguchi, Takashi; Yoo, Won Jong

doi:10.1002/aelm.202100988

Cited by 9 publications

(16 citation statements)

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“…Nevertheless, the 1D edge contacts provide not only good contact properties but also unprecedented features such as contrary FLP behaviors (Fermi‐level depinning in MoS 2 and strong FLP in WSe 2 and WS 2 ), [ 40,188,190 ] immunity to contact scaling, [ 26 ] thickness‐dependent carrier injection, [ 136 ] and ultrahigh anisotropic transport. [ 41 ]…”

Section: Discussionmentioning

confidence: 99%

“…[81] Further, the 1D edge contacts can lead to unique electrical features in FET device structures that have been challenging to achieve using typical top contacts, such as Fermi level depinning, immunity to contact scaling, and in-plane anisotropic transport. [26,40,41] With the seamless 1D heterophase of 1T/2H-MoS 2 , Schottky diodes have been demonstrated with a gate-tunable barrier height in the range from 0 to 0.13 eV at high temperatures >150 K. [91] The high flexibility of 2DMs also enabled the preparation of high-performance flexible electronics with 1D edge contacts. Flexible graphene FETs were fabricated with 1D edge contacts.…”

Section: Device Applications With Edge Contactsmentioning

confidence: 99%

“…[189,195] Furthermore, Lee et al observed low mobility with an edge-contacted BP device compared to those of top-contacted devices. [41] This observation suggests that the poor MS interface conditions could annihilate the advantages of edge contacts.…”

Section: Challenges Of Edge Contactmentioning

confidence: 99%

“…[39] The edge-contacted 2D devices revealed interesting features, such as Fermilevel depinning, immunity to contact scaling, and ultrahigh anisotropy. [26,40,41] Meanwhile, Kappera et al first reported a phase-engineering of MoS 2 from 2H phase to 1T phase by…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Recent Progress in 1D Contacts for 2D‐Material‐Based Devices

et al. 2022

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It is therefore becoming increasingly important to analyze the electronic properties of nanometer scale semiconductors from the quantum mechanical perspective. Due to their atomic thickness, 2D materials (2DMs) are considered to be the best candidates for revealing the quantum mechanical properties when used as semiconducting channel materials in electronic devices, thus representing alternatives to the conventional semiconducting materials such as Si and GaAs. [1] However, the use of 2DMs leads to large contact resistance (R C ) when they are in contact with metallic electrodes, since they form a metallic interface that depends on van der Waals (vdW) bonding, which induces the vdW gap and generates metalinduced gap states, ultimately resulting in Fermi-level pinning (FLP). [2,3] As a result, the electronic mobility of the metal-contacted 2DM based devices is found to be much lower than the theoretically expected value, thus preventing their quantum properties from being observed. Therefore, minimizing the R C of the devices using 2DMs represents the most important challenge for exploring the novel quantum electronic properties of the devices. In this regard, there have been substantial efforts to reduce the R C by using novel contact strategies. [4,5] Clean vdW contacts either by transferring metal/ semimetal electrodes or depositing indium on 2D semiconductors have been proposed to obtain high-quality metal-semiconductor (MS) interfaces without generating metallization induced defects. [6][7][8][9][10][11] High density doping achieved by chemical dopants, substitutional doping, solid oxides, and semimetals has also been utilized to reduce the R C significantly. [12][13][14][15][16][17][18][19][20] However, such contacts were typically placed onto the vdW surface of 2D semiconductors resulting in the formation of vdW tunneling barriers as well as the limitation in lateral scaling of the devices. Here, the 1D edge contact methods have been studied intensively as a very suitable technique for achieving a vdW gap-free electrical contact in scaled 2D devices.Edge-contacted 2D devices were first demonstrated for the purpose of suppressing scattering from the surface of 2DMs by encapsulating graphene with 2D hBN. [21] Following this initial report, the 1D edge contact method became more widely employed due to its additional advantages in the operation of 2D devices: the realization of Fermi-level depinning Recent studies have intensively examined 2D materials (2DMs) as promising materials for use in future quantum devices due to their atomic thinness. However, a major limitation occurs when 2DMs are in contact with metals: a van der Waals (vdW) gap is generated at the 2DM-metal interfaces, which induces metal-induced gap states that are responsible for an uncontrollable Schottky barrier (SB), Fermi-level pinning (FLP), and high contact resistance (R C ), thereby substantially lowering the electronic mobility of 2DMbased devices. Here, vdW-gap-free 1D edge contact is reviewed for use in 2D devices with substantially su...

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Section: Discussionmentioning

confidence: 99%

Section: Device Applications With Edge Contactsmentioning

confidence: 99%

Section: Challenges Of Edge Contactmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Recent Progress in 1D Contacts for 2D‐Material‐Based Devices

et al. 2022

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Plasma and Gas‐based Semiconductor Technologies for 2D Materials with Computational Simulation & Electronic Applications

Kim,

Kim

et al. 2024

Adv Elect Materials

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The technique of plasma processing is beneficial for wafer cleaning and precision etching of integrated circuits and essential in manufacture of advanced semiconductor devices with unmatched perfection. Research on two‐dimensional (2D) materials, such as transition metal dichalcogenides(TMDs), offers a promising solution to the challenges in semiconductor miniaturization. TMDs, with their atomic layer thicknesses and silicon‐like bandgaps, can be integrated using existing plasma systems. Different 2D crystal structures, such as 1T and 2H configurations, exhibit distinctive properties. Computational approaches are also developed to provide guidelines for controlled synthesis and etching of large‐scale and high‐quality 2D materials. Plasma/gas‐surface interactions during the synthesis, etching, and phase transformation of 2D materials are explored using atomistic simulations such as density functional theory and molecular dynamics. The reaction energetics, chemical species, and associated kinetics are discovered in the simulation study. These results decipher various mechanisms of 2D materials processing at the microscopic scale and predict certain optimal process parameters. Plasma/gas‐based semiconductor technologies are crucial in electronics because they enable production of advanced semiconductors. Plasma/gas etching allows precise and selective removal of material and plasma‐enhanced chemical vapor deposition enhances chemical reactions for efficient film deposition; therefore, these processes are majorly important for harnessing 2D materials in electronic applications.

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Percolation-Based Metal–Insulator Transition in Black Phosphorus Field Effect Transistors

Ali

Lee

Ngo

et al. 2023

ACS Appl. Mater. Interfaces

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The existence of a novel phenomenon, such as the metal−insulator transition (MIT) in two-dimensional (2D) systems, affords emerging functional properties that provide new aspects for future electronics and optoelectronics. Here, we report the observation of the MIT in black phosphorus field effect transistors by tuning the carrier density (n) controlled by back-gate bias. We find that the conductivity follows an n dependence as σ(n) ∝ n α with α ∼ 1, which indicates the presence of screened Coulomb impurity scattering at high carrier densities in the temperature range of 10−300 K. As n decreases, the screened Coulomb impurity scattering breaks down, developing strong charge density inhomogeneity leading to a percolation-based transition at the critical carrier density (n C ). At low carrier densities (n < n C ), the system is in the insulating regime, which is expressed by Mott variable range hopping that demonstrates the role of disorder in the system. In addition, the extracted average values of critical exponent δ are ∼1.29 ± 0.01 and ∼1.14 ± 0.01 for devices A and B, respectively, consistent with the 2D percolation exponent of 4 / 3 , confirming the 2D percolation-based MIT in BP devices. Our findings strongly suggest that the 2D MIT observed in BP is a classical percolation-based transition caused by charge inhomogeneity induced by screened Coulomb charge impurity scattering around a transition point controlled by n through backgate bias.

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Ultrahigh Anisotropic Transport Properties of Black Phosphorus Field Effect Transistors Realized by Edge Contact

Cited by 9 publications

References 51 publications

Recent Progress in 1D Contacts for 2D‐Material‐Based Devices

Recent Progress in 1D Contacts for 2D‐Material‐Based Devices

Plasma and Gas‐based Semiconductor Technologies for 2D Materials with Computational Simulation & Electronic Applications

Percolation-Based Metal–Insulator Transition in Black Phosphorus Field Effect Transistors

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