Intrinsic Transport in 2D Heterostructures Mediated through h-BN Tunneling Contacts

Murthy, Akshay A.; Stanev, Teodor K.; Cain, Jeffrey D.; Hao, Shiqiang; LaMountain, Trevor; Kim, Sungkyu; Speiser, Nathaniel; Watanabe, Kenji; Taniguchi, Takashi; Wolverton, Christopher; Stern, Nathaniel P.; Dravid, Vinayak P.

doi:10.1021/acs.nanolett.8b00444

Cited by 45 publications

(46 citation statements)

References 68 publications

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“…Atomic scale characterization of the interfaces by scanning transmission electron microscopy (STEM) has suggested that the degradation is associated with the damage of TMDs in the contact layer by invasion of metal atoms [12][13][14] . Interface engineering, such as insertion of additional vdW layers (graphene 15 , hexagonal boron nitride (hBN) 16 , etc. ), mechanical transfer of metal films 13 and incorporation with indium 17 , are explored to form ideal vdW contacts that are free from the chemical disorder.…”

mentioning

confidence: 99%

Van der Waals interfacial reconstruction in monolayer transition-metal dichalcogenides and gold heterojunctions

Luo

Zhang

et al. 2020

Nat Commun

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The structures and properties of van der Waals (vdW) heterojunctions between semiconducting two-dimensional transition-metal dichalcogenides (2D TMDs) and conductive metals, such as gold, significantly influence the performances of 2D-TMD based electronic devices. Chemical vapor deposition is one of the most promising approaches for large-scale synthesis and fabrication of 2D TMD electronics with naturally formed TMD/metal vdW interfaces. However, the structure and chemistry of the vdW interfaces are less known. Here we report the interfacial reconstruction between TMD monolayers and gold substrates. The participation of sulfur leads to the reconstruction of Au {001} surface with the formation of a metastable Au 4 S 4 interfacial phase which is stabilized by the top MoS 2 and WS 2 monolayers. Moreover, the enhanced vdW interaction between the reconstructed Au 4 S 4 interfacial phase and TMD monolayers results in the transition from n-type TMD-Au Schottky contact to ptype one with reduced energy barrier height.

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confidence: 99%

Van der Waals interfacial reconstruction in monolayer transition-metal dichalcogenides and gold heterojunctions

Luo

Zhang

et al. 2020

Nat Commun

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“…As shown in Figure S5a,b (Supporting Information), the I–V trends are asymmetric, which is likely due to the differences in energies between MoS 2 , WS 2 , and metal work functions at the contacts. This asymmetry in the transport curves about zero applied voltage is attributed to asymmetric Schottky barriers across the heterojunction . Briefly, due to differences in the energy levels of the sulfur vacancy states in MoS 2 compared to WS 2 , inequivalent Schottky barriers form at each metal/semiconductor interface leading to the observed current behavior.…”

mentioning

confidence: 99%

Spatial Mapping of Hot‐Spots at Lateral Heterogeneities in Monolayer Transition Metal Dichalcogenides

Yasaei

Murthy

et al. 2019

Advanced Materials

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disulfide (MoS 2 ) and tungsten disulfide (WS 2 ), tend to exhibit appreciable direct bandgaps and correspondingly large on/off ratios, [1] moderately high carrier mobilities, [2,3] and near minimum subthreshold swings. [4] Furthermore, novel functionalities in these materials can be realized by interfacing similar and/or dissimilar materials in the form of vertical or lateral heterostructures. [5] For example, grain boundaries (GBs) formed through vapor-phase deposition of transition metal dichalcogenide (TMD) films demonstrate gate tunable memristor behavior, which is promising for future neuromorphic computing applications. [6] Additionally, lateral heterojunctions formed between dissimilar TMDs, such as MoS 2 -WS 2 , [7,8] have been found to demonstrate excellent photoresponses and on/off ratios that exceed values achieved in the individual constituents. These systems form what is referred to as a type II junction, where the valence band maxima lies in the WS 2 while the conduction band minima lies in MoS 2 . As such, they provide a unique platform for spatial control of charge carriers within a single atomic layer. [8] Lateral heterojunctions of 2D TMDs with semimetallic 2D materials such as graphene [9,10] have also been demonstrated for realizing ultrascaled contacts for truly nanoscale electronic applications. Due to strong in-plane bonding between the atomic layers, lateral interfaces have shown to exhibit comparable or even improved electronic performance compared with vertical (van der Waals) junctions, which is particularly interesting given the few orders of magnitude smaller contact area. [10,11] The ability to tune the carrier concentration in 2D materials through gating allows for unpinning of the Fermi level and elimination of Schottky barriers resulting from band alignment in MoS 2 -graphene lateral heterojunctions. [10,11] While lateral interfaces offer various intriguing opportunities, their impact on power dissipation has been largely unexplored. For example, lattice distortions at GBs and alterations in the band structure at heterojunctions could potentially be detrimental to device performance and reliability by localizing power dissipation and inducing the formation of nanoscopic hot-spots. [12] These hot-spots can limit drive currents, [13] modify optical and electronic properties, [2,14] or induce premature Lateral heterogeneities in atomically thin 2D materials such as in-plane heterojunctions and grain boundaries (GBs) provide an extrinsic knob for manipulating the properties of nano-and optoelectronic devices and harvesting novel functionalities. However, these heterogeneities have the potential to adversely affect the performance and reliability of the 2D devices through the formation of nanoscopic hot-spots. In this report, scanning thermal micro scopy (SThM) is utilized to map the spatial distribution of the temperature rise within monolayer transition metal dichalcogenide (TMD) devices upon dissipating a high electrical power through a lateral interface. The results directly d...

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“…CVD assisted by sodium chloride (NaCl) requires lower growth temperatures, as Na precursors condensate on the substrate and reduce reaction energies [73]. Given that the properties of 2D materials are susceptible to external environments, the encapsulation of HSs between hBN sheets has been recently obtained [77], showing that both photovoltaic and hot electron generation lead to photocurrents that depend on the biasing conditions.…”

Section: Interfacementioning

confidence: 99%

Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides

Ávalos-Ovando

Mastrogiuseppe

Ulloa

2019

J. Phys.: Condens. Matter

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The growth and exfoliation of two-dimensional (2D) materials have led to the creation of edges and novel interfacial states at the juncture between crystals with different composition or phases. These hybrid heterostructures (HSs) can be built as vertical van der Waals stacks, resulting in a 2D interface, or as stitched adjacent monolayer crystals, resulting in one-dimensional (1D) interfaces. Although most attention has been focused on vertical HSs, increasing theoretical and experimental interest in 1D interfaces is evident. In-plane interfacial states between different 2D materials inherit properties from both crystals, giving rise to robust states with unique 1D non-parabolic dispersion and strong spinorbit effects. With such unique characteristics, these states provide an exciting platform for realizing 1D physics. Here, we review and discuss advances in 1D heterojunctions, with emphasis on theoretical approaches for describing those between semiconducting transition metal dichalcogenides M X 2 (with M =Mo, W and X= S, Se, Te), and how the interfacial states can be characterized and utilized. We also address how the interfaces depend on edge geometries (such as zigzag and armchair) or strain, as lattice parameters differ across the interface, and how these features affect excitonic/optical response. This review is intended to serve as a resource for promoting theoretical and experimental studies in this rapidly evolving field.

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Intrinsic Transport in 2D Heterostructures Mediated through h-BN Tunneling Contacts

Cited by 45 publications

References 68 publications

Van der Waals interfacial reconstruction in monolayer transition-metal dichalcogenides and gold heterojunctions

Van der Waals interfacial reconstruction in monolayer transition-metal dichalcogenides and gold heterojunctions

Spatial Mapping of Hot‐Spots at Lateral Heterogeneities in Monolayer Transition Metal Dichalcogenides

Lateral heterostructures and one-dimensional interfaces in 2D transition metal dichalcogenides

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