Morphology‐Control Growth of Graphene Islands by Nonlinear Carbon Supply

Abstract

Controlling the morphology of graphene and other two-dimensional (2D) materials in chemical vapor deposition (CVD) growth is crucial because the morphology reflects the crystal quality of as-synthesized nanomaterials in a certain way, and consequently it indirectly represents the physical properties of 2D materials such as band gap, selective ion transportation, and impermeability. However, precise control of the morphology is limited by the complex formation mechanism and sensitive growth-environment factors of graphene. Therefore, the CVD synthesis of single-crystal hexagonal-shaped graphene islands with specific sizes is challenging. Herein, an unconventional nonlinear carbon supply growth strategy is proposed to realize controllable CVD growth of desired hexagonal graphene islands with specific sizes on Cu substrates. Large-area graphene films of isolated islands with desired densities, sizes, and distances between the islands were successfully synthesized. Subsequently, the direct growth of a planar-tunnel-junction structure based on two parallel gapped graphene islands was achieved by specific adjustment of the growth and etching processes of graphene CVD synthesis. We therefore demonstrated that the nonlinear carbon supply growth strategy is a reliable method for the synthesis of high-quality graphene and can facilitate the direct growth of graphene-based nanodevices in the future.

Growth Anisotropy and Morphology Evolution of Line Defects in Monolayer MoS2: Atomic‐Level Observation, Large‐Scale Statistics, and Mechanism Understanding

“…Various compact shapes (e.g., hexagons, rectangles, triangles, etc.) and dendritic domains have been thermodynamically or kinetically grown via tailoring the precursor concentration, [1][2][3][4][5][6] growth temperature, [7,8] and substrate symmetry (top panel of Figure 1), [9,10] which tunes the percentage and structure of edge atoms and inspires special electrocatalytic, [11][12][13] optical, [14] and magnetic performances. [15] On the atomic scale, the defect is an important object to investigate.…”

Nonepitaxial Wafer‐Scale Single‐Crystal 2D Materials on Insulators

“…[5][6][7][8] To date, large-area monolayer hBN and graphene with high potential for industrial production have been fabricated on single-crystal metal foil. [9][10][11][12][13][14] Uniform multilayer hBN films and few-layer stacked graphene (AB-stacked bilayer and ABAstacked trilayer) have been synthesized on Ni(111) and CuNi(111) substrates. [15,16] In addition, many efforts have been devoted to growing high-quality large-area hBN and graphene layers on metal substrates with improved crystallinity and uniformity.…”

“…The synthesis of high-quality 2D materials, such as graphene and hexagonal boron nitride (hBN), on metals and insulators using chemical vapor deposition (CVD) is a key research topic that directly influences the development and use of 2D materials in the semiconductor sector [4][5][6] . To date, high-quality large-area graphene and hBN films with high potential for industrial production have been fabricated on single-crystal metal foil [7][8][9][10][11][12][13] . Moreover, few-layered stacked graphene (AB-stacked bilayer and ABA-stacked trilayer graphene) and multilayered hBN films with highly uniform layers have been synthesized on CuNi(111) and Ni(111) substrates 14,15 , and there have been several attempts to improve the crystallinity and uniformity of graphene and hBN with the aim of fabricating high-quality large-area 2D layers on metal substrates [16][17][18][19][20] .…”

Exact Self-Similar Patterns of Atomic-Layer Boron Nitride with Koch Fractal Complexity

“…However, unlike previous studies, we continuously moved the system away from thermodynamic equilibrium and finely controlled the evolution of the h-BN morphology. Be consistent with previous studies of graphene and MoS 2 growth: 3,35,36 When the carrier gas flow is small, the h-BN domains are regular triangles on the substrate (Figure S2); when the carrier gas flow is extremely large, the h-BN domains exhibit the typical random dendritic morphology (Figure S3). Notably, when at moderate gas loads, the system does not deviate too far from equilibrium compared to that of classic dendritic structure, and the exact fractal atomic-layer h-BN Koch snowflake emerges (Figure 1).…”