Heterogeneous integration of hexagonal boron nitride on bilayer quasi‐free‐standing epitaxial graphene and its impact on electrical transport properties

Hollander, Matthew J.; Agrawal, Ashish Kumar; Bresnehan, Michael S.; LaBella, Michael; Trumbull, Kathleen A.; Cavalero, Randal; Snyder, David W.; Datta, Suman; Robinson, Joshua A.

doi:10.1002/pssa.201228683

Cited by 14 publications

(8 citation statements)

References 37 publications

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“…Thus, the distinct indications of disrupted current flow in Figure d,e could be explained by the step edges in R3 acting as resistive or reflective barriers obstructing current flow. The step edges are also taller in R3 compared to R1 and R2 (AFM images, Supporting Information Figure S5), which has previously been shown to negatively affect the electrical properties of graphene on SiC. − The AFM images also show that the terraces between steps in the substrate are flat.…”

Section: Resultsmentioning

confidence: 99%

Electrical Homogeneity Mapping of Epitaxial Graphene on Silicon Carbide

Whelan

Panchal

Petersen³

et al. 2018

ACS Appl. Mater. Interfaces

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Epitaxial graphene is a promising route to wafer-scale production of electronic graphene devices. Chemical vapor deposition of graphene on silicon carbide offers epitaxial growth with layer control but is subject to significant spatial and wafer-to-wafer variability. We use terahertz time-domain spectroscopy and micro four-point probes to analyze the spatial variations of quasi-freestanding bilayer graphene grown on 4 in. silicon carbide (SiC) wafers and find significant variations in electrical properties across large regions, which are even reproduced across graphene on different SiC wafers cut from the same ingot. The dc sheet conductivity of epitaxial graphene was found to vary more than 1 order of magnitude across a 4 in. SiC wafer. To determine the origin of the variations, we compare different optical and scanning probe microscopies with the electrical measurements from nano- to millimeter scale and identify three distinct qualities of graphene, which can be attributed to the microstructure of the SiC surface.

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Section: Resultsmentioning

confidence: 99%

Electrical Homogeneity Mapping of Epitaxial Graphene on Silicon Carbide

Whelan

Panchal

Petersen³

et al. 2018

ACS Appl. Mater. Interfaces

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“…This photoluminescence quenching is consistent with what is observed for the WSe 2 flakes on the suspended graphene. One can expect a significant reduction in surface optical phonon scattering in the graphene layer when the substrate is removed, , which would be a source of enhancement in the efficiency of charge carrier collection in the layer and thus quenching of the PL.…”

Section: Resultsmentioning

confidence: 99%

Freestanding van der Waals Heterostructures of Graphene and Transition Metal Dichalcogenides

Azizi¹,

Eichfeld²,

et al. 2015

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Vertical stacking of two-dimensional (2D) crystals has recently attracted substantial interest due to unique properties and potential applications they can introduce. However, little is known about their microstructure because fabrication of the 2D heterostructures on a rigid substrate limits one's ability to directly study their atomic and chemical structures using electron microscopy. This study demonstrates a unique approach to create atomically thin freestanding van der Waals heterostructures-WSe2/graphene and MoS2/graphene-as ideal model systems to investigate the nucleation and growth mechanisms in heterostructures. In this study, we use transmission electron microscopy (TEM) imaging and diffraction to show epitaxial growth of the freestanding WSe2/graphene heterostructure, while no epitaxy is maintained in the MoS2/graphene heterostructure. Ultra-high-resolution aberration-corrected scanning transmission electron microscopy (STEM) shows growth of monolayer WSe2 and MoS2 triangles on graphene membranes and reveals their edge morphology and crystallinity. Photoluminescence measurements indicate a significant quenching of the photoluminescence response for the transition metal dichalcogenides on freestanding graphene, compared to those on a rigid substrate, such as sapphire and epitaxial graphene. Using a combination of (S)TEM imaging and electron diffraction analysis, this study also reveals the significant role of defects on the heterostructure growth. The direct growth technique applied here enables us to investigate the heterostructure nucleation and growth mechanisms at the atomic level without sample handling and transfer. Importantly, this approach can be utilized to study a wide spectrum of van der Waals heterostructures.

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“…The role of SiC morphology on transport properties of graphene grown by silicon sublimation was discussed by several groups. [47][48][49] It has been reported that SiC step edge density, 50 step height, 51 and step bunching 52,53 give rise to graphene's resistance. The step edge resistivity in monolayer graphene was evaluated by scanning potentiometry in a scanning tunneling microscope 51 and later associated with the abrupt variation in potential and doping due to detachment of graphene from the substrate as it passes over a step.…”

Section: Introductionmentioning

confidence: 99%

Step-edge-induced resistance anisotropy in quasi-free-standing bilayer chemical vapor deposition graphene on SiC

Ciuk

Çakmakyapan

Özbay

et al. 2014

Journal of Applied Physics

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The transport properties of quasi-free-standing (QFS) bilayer graphene on SiC depend on a range of scattering mechanisms. Most of them are isotropic in nature. However, the SiC substrate morphology marked by a distinctive pattern of the terraces gives rise to an anisotropy in graphene's sheet resistance, which may be considered an additional scattering mechanism. At a technological level, the growth-preceding in situ etching of the SiC surface promotes step bunching which results in macro steps ∼ 10? nm in height. In this report, we study the qualitative and quantitative effects of SiC steps edges on the resistance of epitaxial graphene grown by chemical vapor deposition. We experimentally determine the value of step edge resistivity in hydrogen-intercalated QFS-bilayer graphene to be ∼ 190? Ωμ m for step height hS? =? 10? nm and provide proof that it cannot originate from mechanical deformation of graphene but is likely to arise from lowered carrier concentration in the step area. Our results are confronted with the previously reported values of the step edge resistivity in monolayer graphene over SiC atomic steps. In our analysis, we focus on large-scale, statistical properties to foster the scalable technology of industrial graphene for electronics and sensor applications. © 2014 AIP Publishing LLC

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Heterogeneous integration of hexagonal boron nitride on bilayer quasi‐free‐standing epitaxial graphene and its impact on electrical transport properties

Cited by 14 publications

References 37 publications

Electrical Homogeneity Mapping of Epitaxial Graphene on Silicon Carbide

Electrical Homogeneity Mapping of Epitaxial Graphene on Silicon Carbide

Freestanding van der Waals Heterostructures of Graphene and Transition Metal Dichalcogenides

Step-edge-induced resistance anisotropy in quasi-free-standing bilayer chemical vapor deposition graphene on SiC

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