Density functional study of Ga intercalation at graphene/SiC heterointerface

Nayir, Nadire

doi:10.1557/s43578-022-00530-4

Cited by 4 publications

(14 citation statements)

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“…Even though defects in the graphene layer are effective to enhance intercalation, the nature of the defects and their impact on intercalation and chemical conversion of intercalants has remained elusive. Two recent studies using reactive force fields (ReaxFF) and density functional theory (DFT) , show that Ga intercalation through mono- and divacancies is kinetically hindered while larger size defects (>divacancy) significantly lower the kinetic barrier encountered during Ga penetration through graphene and, by consequence, lower the growth temperature required for the 2D-Ga fabrication.…”

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confidence: 99%

Toward a Mechanistic Understanding of the Formation of 2D-GaN_x in Epitaxial Graphene

et al. 2022

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Ultrathin 2D-GaN x can be formed by Ga intercalation into epitaxial graphene (EG) on SiC followed by nitridation in ammonia. Defects in the graphene provide routes for intercalation, but the nature and role of the defects have remained elusive. Here we examine the influence of graphene layer thickness and chemical functionalization on Ga intercalation and 2D-GaN x formation using a combination of experimental and theoretical studies. Thin buffer layer regions of graphene near steps on SiC readily undergo oxygen functionalization when exposed to air or a He/O 2 plasma in contrast to thicker regions which are not chemically modified. Oxygen functionalization is found to inhibit Ga intercalation leading to accumulation of Ga droplets on the surface. In contrast, Ga readily intercalates between EG and SiC in the thicker graphene regions that do not contain oxygen. When NH 3 annealing is carried out immediately after Ga exposure, 2D-GaN x formation is observed only in the oxygen-functionalized regions, and Ga intercalated under thicker nonfunctionalized graphene does not convert to GaN x . Density functional theory calculations demonstrate that oxygen functionalization of graphene alters the binding energy of Ga and NH 3 species to the graphene surface. The presence of hydroxyl groups on graphene inhibits binding of Ga to the surface; however, it enhances the chemical reactivity of the graphene surface to NH 3 which, in turn, enhances Ga binding and facilitates the formation of 2D-GaN x . By modifying the EG process to produce oxygen-functionalized buffer layer graphene, uniformly intercalated 2D-GaN x is obtained across the entire substrate surface.

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Toward a Mechanistic Understanding of the Formation of 2D-GaN_x in Epitaxial Graphene

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“…Also, ReaxFF differs from the so-called “first generation” reactive force fields such as Tersoff , and Brenner by applying a significantly longer-ranged bond-order relationship, which makes it possible to achieve accurate reaction kinetics. The ReaxFF framework has been successfully applied to a wide range of 2D systems − and their defect formation, growth mechanisms and characterization, as shown in the following examples.…”

Section: Discussionmentioning

confidence: 99%

“…The nonuniformities that influence device performance can be divided in two groups: inherited during synthesis (intrinsic) and acquired during device fabrication process. Intrinsic nonuniformities include atomic impurities, lattice defects, ,, GBs, wrinkles and ruptures that result in strain, doping and/or charge transfer, often possessing variation at the nanometer scale. Acquired nonuniformities that come from the transfer process and nanofabrication can be partially eliminated by post-transfer cleaning procedures (annealing) or by using Soxhlet extractor for improving quality of transfer.…”

Section: Discussionmentioning

confidence: 99%

“…The ReaxFF framework has been successfully applied to a wide range of 2D systems 50−52 and their defect formation, growth mechanisms and characterization, as shown in the following examples. 46,52 used a combination of ReaxFF-and DFT-based simulations to study defects in graphene, which can act as pathways for Ga intercalation into the interface between graphene and SiC. The results show that the sizes of vacancy defects ranging from single carbon vacancy (SV) to multiple carbon vacancy (3 and 4 V) can affect the thermodynamic and kinetic preference of intercalant between the adsorption on graphene surface or the intercalation at the interface.…”

Section: Introductionmentioning

confidence: 99%

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Recent Advances in 2D Material Theory, Synthesis, Properties, and Applications

et al. 2023

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Two-dimensional (2D) material research is rapidly evolving to broaden the spectrum of emergent 2D systems. Here, we review recent advances in the theory, synthesis, characterization, device, and quantum physics of 2D materials and their heterostructures. First, we shed insight into modeling of defects and intercalants, focusing on their formation pathways and strategic functionalities. We also review machine learning for synthesis and sensing applications of 2D materials. In addition, we highlight important development in the synthesis, processing, and characterization of various 2D materials (e.g., MXnenes, magnetic compounds, epitaxial layers, low-symmetry crystals, etc.) and discuss oxidation and strain gradient engineering in 2D materials. Next, we discuss the optical and phonon properties of 2D materials controlled by material inhomogeneity and give examples of multidimensional imaging and biosensing equipped with machine learning analysis based on 2D platforms. We then provide updates on mix-dimensional heterostructures using 2D building blocks for next-generation logic/memory devices and the quantum anomalous Hall devices of high-quality magnetic topological insulators, followed by advances in small twist-angle homojunctions and their exciting quantum transport. Finally, we provide the perspectives and future work on several topics mentioned in this review.

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“…The ReaxFF reactive force field method developed by van Duin et al for hydrocarbons [19] is a bondorder dependent potential where charge on each atom is determined based on the polarizable charge method [47], potentially suitable to model any type Illustration of the scope of this review which focuses on ReaxFF force fields and their applications to 2D materials categorized into six subgroups: (i) TMDs [24][25][26], (ii) hybrid materials [27][28][29][30], (iii) graphene/h-BN [31][32][33][34], (iv) MXenes [35][36][37][38], (v) group III materials [39][40][41][42] and (vi) group IV and V materials [43][44][45][46]. Reprinted with permission from [24].…”

Section: Reaxff Reactive Force Fieldmentioning

confidence: 99%

Modeling and simulations for 2D materials: a ReaxFF perspective

et al. 2023

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Recent advancements in the field of two-dimensional (2D) materials have led to the discovery of a wide range of 2D materials with intriguing properties. Atomistic-scale simulation methods have played a key role in these discoveries. In this review, we provide an overview of the recent progress in ReaxFF force field developments and applications in modeling of the following layered and nonlayered 2D materials: graphene, transition metal dichalcogenides, MXenes, hexagonal boron nitrides, groups III-, IV- and V-elemental materials, as well as the mixed dimensional van der Waals heterostructures. We discuss knowledge gaps and challenges associated with the synthesis and characterization of 2D materials. We close this review with an outlook addressing the challenges as well as plans regarding ReaxFF development and possible large-scale simulations, which should be helpful to guide experimental studies in a discovery of new materials and devices.

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Density functional study of Ga intercalation at graphene/SiC heterointerface

Cited by 4 publications

References 61 publications

Toward a Mechanistic Understanding of the Formation of 2D-GaN_x in Epitaxial Graphene

Toward a Mechanistic Understanding of the Formation of 2D-GaN_x in Epitaxial Graphene

Recent Advances in 2D Material Theory, Synthesis, Properties, and Applications

Modeling and simulations for 2D materials: a ReaxFF perspective

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Density functional study of Ga intercalation at graphene/SiC heterointerface

Cited by 4 publications

References 61 publications

Toward a Mechanistic Understanding of the Formation of 2D-GaNx in Epitaxial Graphene

Toward a Mechanistic Understanding of the Formation of 2D-GaNx in Epitaxial Graphene

Recent Advances in 2D Material Theory, Synthesis, Properties, and Applications

Modeling and simulations for 2D materials: a ReaxFF perspective

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Product

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Toward a Mechanistic Understanding of the Formation of 2D-GaN_x in Epitaxial Graphene

Toward a Mechanistic Understanding of the Formation of 2D-GaN_x in Epitaxial Graphene