Atomic mechanism for the growth of wafer-scale single-crystal graphene: theoretical perspective and scanning tunneling microscopy investigations

Abstract

Chemical vapor deposition (CVD) is the most promising approach for producing low-cost, highquality, and large area graphene. Revealing the graphene growth mechanism at the atomic-scale is of great importance for realizing single crystal graphene (SCG) over wafer scale. Density functional theoretical (DFT) calculations are playing an increasingly important role in revealing the structure of the most stable carbon species, understanding the evolution processes, and disclosing the active sites. Scanning tunneling microscopy (STM) is a powerful surface characterization tool to illustrate the real space distribution and atomic structures of growth intermediates during the CVD process. Combining them together can provide valuable information to improve the atomically controlled growth of SCG. Starting from a basic concept of the substrate effect on realizing SCG, this review covers the progress made in theoretical investigations on various carbon species during graphene growth on different transition metal substrates, in the STM study of the structural intermediates on transition metal surfaces, and in synthesizing graphene nanoribbons with atomic-precise width and edge structure, ending with a perspective on the future development of 2D materials beyond graphene.

Epitaxial Growth of Flat, Metallic Monolayer Phosphorene on Metal Oxide

“…Since the advent of graphene, two-dimensional (2D) materials have been extensively explored due to their outstanding mechanical and electronic properties that hold great promise for device applications. − In particular, for 2D elemental structures, such as borophene, silicene, germanene, and stanene, both theoretical and experimental studies − have revealed the critical role of substrate in the epitaxial growth, as they usually require a metallic substrate as catalyst with appropriate lattice match, except for a few cases of van der Waals epitaxy on inert substrates. , Unfortunately, the strong interfacial interaction between substrate and the grown structure results in difficulty in transferring of the structure onto a device-ready surface, which restricts practical applications. − An attractive yet challenging way is to synthesize 2D materials directly on a nonmetallic substrate, such as semiconductors or insulators. − As a recent example, via a delicately designed precursor with a C–F motif at the right position, Kolmer et al rationally fabricated nanographene and nanoribbons on a rutile TiO 2 (001) . However, the design and synthesis of these molecular precursors are daunting challenges. − In this sense, molecular beam epitaxy (MBE) on an appropriate substrate has the benefit of sole usage of their bulk crystalline counterparts as precursors, such as graphite rods, silicon and germanium wafers, tin, boron rods, phosphorus (P) crystals, and antimony and bismuth granules. , During the past decade, MBE has also become one of the most popular approaches for large-scale synthesis of 2D materials.…”

Surface Engineering of Two‐Dimensional Materials

“…High‐throughput calculations can also provide valuable information for selecting the suitable experimentally known 3D compounds that can be exfoliated into 2D materials . Furthermore, multiple surface science characterization techniques, e. g. combined STM, XPS, Ultraviolet photoelectron spectroscopy (UPS), low‐energy electron microscopy (LEEM) and device evaluation are required to establish a complete picture of the growth mechanism, morphology and electronic properties …”

On-surface activation of benzylic C-H bonds for the synthesis of pentagon-fused graphene nanoribbons

“…Precision synthesis of GNRs appears as a major challenge. To this end, on-surface synthesis based on the polymerization and planarization of tailor-made molecular precursors on metal surfaces under ultrahigh vacuum (UHV) conditions appears particularly powerful and offers the additional advantage of in-situ monitoring by atomic-resolution scanning probe microscopy [5][6][7][8][9][10]. Since the initial demonstration of 7-atomwide armchair-type GNRs (7-AGNRs) on a Au(111) surface using 10,10'-dibromo-9,9'-bianthryl (DBBA) as a precursor [11], a range of GNRs with different structures have been prepared via on-surface synthesis, such as armchair GNRs (N-AGNRs) with different widths N (N = 5, 6, 8, 9, 10, 13, 15 and 17) [12][13][14][15][16][17][18][19], zigzag GNRs (ZGNRs) [20], chevron-type GNRs [11,21], chiral (3,1)-GNRs containing zigzag and armchair edges [22], and heteroatom-doped GNRs with boron, nitrogen, oxygen, or sulfur [23][24][25][26][27][28][29][30].…”