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Title: Point Defects and Grain Boundaries in Rotationally Commensurate MoS 2 on Epitaxial Graphene

Authors:
; ; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Argonne-Northwestern Solar Energy Research Center (ANSER)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1371250
DOE Contract Number:
SC0001059
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. C; Journal Volume: 120; Journal Issue: 37; Related Information: ANSER partners with Northwestern University (lead); Argonne National Laboratory; University of Chicago; University of Illinois, Urbana-Champaign; Yale University
Country of Publication:
United States
Language:
English
Subject:
catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis (natural and artificial), bio-inspired, hydrogen and fuel cells, electrodes - solar, defects, charge transport, spin dynamics, membrane, materials and chemistry by design, optics, synthesis (novel materials), synthesis (self-assembly)

Citation Formats

Liu, Xiaolong, Balla, Itamar, Bergeron, Hadallia, and Hersam, Mark C. Point Defects and Grain Boundaries in Rotationally Commensurate MoS 2 on Epitaxial Graphene. United States: N. p., 2016. Web. doi:10.1021/acs.jpcc.6b02073.
Liu, Xiaolong, Balla, Itamar, Bergeron, Hadallia, & Hersam, Mark C. Point Defects and Grain Boundaries in Rotationally Commensurate MoS 2 on Epitaxial Graphene. United States. doi:10.1021/acs.jpcc.6b02073.
Liu, Xiaolong, Balla, Itamar, Bergeron, Hadallia, and Hersam, Mark C. 2016. "Point Defects and Grain Boundaries in Rotationally Commensurate MoS 2 on Epitaxial Graphene". United States. doi:10.1021/acs.jpcc.6b02073.
@article{osti_1371250,
title = {Point Defects and Grain Boundaries in Rotationally Commensurate MoS 2 on Epitaxial Graphene},
author = {Liu, Xiaolong and Balla, Itamar and Bergeron, Hadallia and Hersam, Mark C.},
abstractNote = {},
doi = {10.1021/acs.jpcc.6b02073},
journal = {Journal of Physical Chemistry. C},
number = 37,
volume = 120,
place = {United States},
year = 2016,
month = 9
}
  • With reduced degrees of freedom, structural defects are expected to play a greater role in two-dimensional materials in comparison to their bulk counterparts. In particular, mechanical strength, electronic properties, and chemical reactivity are strongly affected by crystal imperfections in the atomically thin limit. Here, ultrahigh vacuum (UHV) scanning tunneling microscopy (STM) and spectroscopy (STS) are employed to interrogate point and line defects in monolayer MoS2 grown on epitaxial graphene (EG) at the atomic scale. Five types of point defects are observed with the majority species showing apparent structures that are consistent with vacancy and interstitial models. The total defect densitymore » is observed to be lower than MoS2 grown on other substrates and is likely attributed to the van der Waals epitaxy of MoS2 on EG. Grain boundaries (GBs) with 30° and 60° tilt angles resulting from the rotational commensurability of MoS2 on EG are more easily resolved by STM than atomic force microscopy at similar scales due to the enhanced contrast from their distinct electronic states. For example, band gap reduction to ~0.8 and ~0.5 eV is observed with STS for 30° and 60° GBs, respectively. In addition, atomic resolution STM images of these GBs are found to agree well with proposed structure models. This work offers quantitative insight into the structure and properties of common defects in MoS2 and suggests pathways for tailoring the performance of MoS2/graphene heterostructures via defect engineering.« less
  • A set of 45{degree} [001] bi-epitaxial YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} thin film grain boundaries was studied to compare the effects of the microstructure on transport properties. The grain boundaries were made using two different deposition techniques: pulsed laser deposition (PLD) and pulsed organometallic beam epitaxy (POMBE). The transport properties were highly dependent on the specific growth conditions used, resulting in both fully resistive and superconducting grain boundaries. Subsequent microstructural analysis of the measured boundaries showed that both types (superconducting and resistive) meandered on the length scale of hundreds of nanometers. The major structural difference between the boundaries was atmore » the atomic scale where the resistive boundary had a 1 nm wide disordered region. The direct correlation of microstructure to transport properties demonstrates the importance of the atomic scale structure in the resulting transport behavior. {copyright} {ital 1996 Materials Research Society.}« less
  • A systematic first-principles non-equilibrium Green's function study is conducted on the contact resistance between a series of metals (Au, Ag, Pt, Cu, Ni, and Pd) and graphene in the side contact geometry. Different factors such as the termination of the graphene edge, contact area, and point defect in contacted graphene are investigated. Notable differences are observed in structural configurations and electronic transport characteristics of these metal-graphene contacts, depending on the metal species and aforementioned influencing factors. It is found that the enhanced chemical reactivity of the graphene due to dangling bonds from either the unsaturated graphene edge or point defectsmore » strengthens the metal-graphene bonding, leading to a considerable contact resistance reduction for weakly interacting metals Au and Ag. For stronger interacting metals Pt and Cu, a slightly reduced contact resistance is found due to such influencing factors. However, the wetting metals Ni and Pd most strongly hybridize with graphene, exhibiting negligible dependence on the above influencing factors. This study provides guidance for the optimization of metal-graphene contacts at an atomic scale.« less