Controlling the orientations of h-BN during growth on transition metals by chemical vapor deposition

Zhao, Ruiqi; Zhao, Xiao-Lei; Ding, Feng; Liu, Zhongfan

doi:10.1039/c6nr09368j

Cited by 39 publications

(51 citation statements)

References 54 publications

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“…The preferential registrations reflect the electron affinity of the B and N atoms, which leads to attractive (repulsive) Coulomb interactions between N (B) atoms and the first-layer Cu atoms, and hence affects the structural stability. We find that the lowest-energy structures for 0° (NIBIII) and 60° (NIBII) orientations exhibit only an energy difference ~0.05 eV, significantly smaller than the thermal energy kBT at the growth temperature (~0.1eV), indicating that the plane-toplane registry is insufficient to achieve mono-oriented growth, in agreement with reported simulations (13).…”

supporting

confidence: 91%

Wafer-scale single-crystal hexagonal boron nitride monolayers on Cu (111)

Chen

Chuu

Tseng

et al. 2020

Nature

500

437

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Ultrathin two-dimensional (2D) semiconducting layered materials offer a great potential to extend the Moore's Law (1). One key challenge for 2D semiconductors is to avoid the formation of charge scattering and trap sites from adjacent dielectrics. The insulating van der Waals layer, hexagonal boron nitride (hBN), is an excellent interface dielectric to 2D semiconductors, efficiently reducing charge scatterings (2, 3). Recent studies have shown the growth of single-crystal hBN films on molten Au surfaces (4) or bulk Cu foils (5). However, using molten Au is not favored in industry due to high cost, cross-contamination, and potential issues of process control and scalability. Cu foils may be suitable for roll-to-roll processes, but unlikely to be compatible with advanced microelectronic fabrication on Si wafers. Thus, only a reliable approach to grow single-crystal hBN on wafers can help realize the broad adoption of 2D layered materials in industry. Previous efforts on growing hBN triangular monolayers on Cu (111) metals have failed to achieve mono-orientation, resulting in unwanted grain boundaries when they merge as films (6,7). Growing singlecrystal hBN on such a high-symmetry surface planes (5,8) is commonly believed to be impossible even in theory. In stark contrast, we have successfully realized the epitaxial growth of single-crystal hBN monolayers on a Cu ( 111) thin film across a 2-inch c-plane sapphire wafer. This surprising result is corroborated by our first-principles calculations, suggesting that the epitaxy to the underlying Cu lattice is enhanced by the lateral docking to Cu (111) steps, to ensure the mono-orientation of hBN monolayers. The obtained singlecrystal hBN, incorporated as an interface layer between MoS2 and HfO2 in a bottom-gate configuration, has enhanced the electrical performance of transistors based on monolayer MoS2. This reliable approach of producing wafer-scale single-crystal hBN truly paves the way for developing futuristic 2D electronics.First, a single-crystal Cu (111) thin film on a wafer is needed. Single-crystal Cu in thick foils can be achieved through recrystallization induced by implanted seeds (5,9). However, for the formation of Cu (111) thin film on a wafer, the crystallinity strongly relies on the underlying substrate lattices. Here we used a c-plane sapphire as the substrate, on which a 500-nm-thick polycrystalline Cu film was sputtered followed by extensive thermal annealing to achieve singlecrystal Cu (111) films (10). One challenge is that Cu (111) tends to form twin grains separated by twin grain boundaries, through kinetic growth processes. Fig. 1a illustrates the atomic arrangements for the typical twinned Cu (111) structure. We find that the post-annealing at a high temperature (1,040 -1,070 °C) in the presence of hydrogen is the key to removing the twin grains, consistent with recent reports (10,11). Figures 1b and 1c show the optical micrographs (OMs) and electron backscatter diffraction (EBSD) patterns for the Cu (111) thin films after annealing at 1,000 °...

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supporting

confidence: 91%

Wafer-scale single-crystal hexagonal boron nitride monolayers on Cu (111)

Chen

Chuu

Tseng

et al. 2020

Nature

500

437

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“…Zhao et al investigated the alignments of triangular h-BN clusters on the (111) surface of FCC metals and the (0001) surface of hexagonal close packed (HCP) metals, respectively (Fig. 70b-e) 1665 . It is revealed that, due to equivalence of ABC… and BCA… configurations of the neighboring terraces of a vicinal FCC(111) surface, h-BN islands tend to align parallelly on neighboring terraces of a vicinal FCC(111) surface.…”

Section: Growth Mechanism Of 2d Materials Via Bottomup Synthesismentioning

confidence: 99%

Recent Progress on Two-Dimensional Materials

Chang¹,

Chen²,

Chen³

et al. 2021

Acta Physico Chimica Sinica

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311

119

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Research on two-dimensional (2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications.In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief background 物理化学学报 Acta Phys. -Chim. Sin. 2021, 37 (12), 2108017 (3 of 151) introduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials (PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.

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“…Several theoretical studies have revealed the growth behaviours of 2D materials including both free-standing and metal-supported graphene 37–41 and h-BN. 42–46 To the best of our knowledge, there is no detailed work revealing the growth mechanism of β-G15 films.…”

Section: Introductionmentioning

confidence: 99%