In Situ Investigating the Mechanism of Graphene Growth by Chemical Vapor Deposition

Abstract

Controlled synthesis of graphene via chemical vapor deposition (CVD) is critical for its practical application. The in-depth understanding of the growth mechanism can effectively promote the fundamental research and guide the synthesis of graphene. In situ characterization techniques allow real-time monitoring the dynamic growth processes, which are expected as powerful tools to provide multiscale insights into reaction procedures and mechanisms under real-time conditions. In this Review, we will give a brief introduction of in situ techniques used to capture the growth processes of graphene. On this basis, the growth mechanism will be discussed. Finally, we will conclude the Review with insights into the challenges and future prospects in this emerging research field.

In Situ Observation of Graphene Growth by Chemical Vapor Deposition Using Ultraviolet Reflection: Implications for Efficient Growth Control in the Industrial Process

“…The growth rate was determined to be 9.8, 7.9, and 2.5 μm 2 /s for H 2 ratios of 3, 4, and 5 vol %, respectively. The H 2 gas in the CVD gas mixture reduces the active species of graphene, and, consequently, the growth rate of the individual graphene domains is reduced with an increasing H 2 ratio. − We continued the observation during the sample cooling-down process to room temperature and confirmed that no graphene growth had occurred.…”

“…During CVD growth, multiple complex chemical reactions occur simultaneously, such as the generation of active species (e.g., CH and C 2 ) due to the decomposition of the hydrocarbon gas sources (e.g., CH 4 and C 2 H 2 ), adsorption/desorption of active species on the Cu surface, their migration on the surface, and nucleation/etching of graphene domains. Particularly, the H 2 gas plays an important role in the generation of active species and the etching of graphene domains. − We therefore investigated the graphene growth process by monitoring individual graphene domains at different H 2 ratios in a CVD gas mixture. As examples, Figure (a)–(c) shows micrographs observed every 14 min during graphene CVD growth at 1050 °C with H 2 4 vol % using a light source with a wavelength of 365 nm.…”

Progress on the in situ imaging of growth dynamics of two-dimensional materials

“…By collecting secondary electron signal, graphene with different layers could be discriminated from the different contrasts. [43][44][45][46][47] To implement STM imaging, an atomically sharp tip is taken close to a conductive surface. Collecting the feedback of tunnelling current, atomic-resolution surface structure can be obtained.…”

“…By collecting secondary electron signal, graphene with different layers could be discriminated from the different contrasts. 43–47…”

Evolution of ordered nanoporous phases during h-BN growth: controlling the route from gas-phase precursor to 2D material by in situ monitoring

“…While it is crucial to understand the growth process, mechanistic and kinetic studies are rare and mostly focus on the growth of nanocarbons. [13][14][15][16] Dehydrogenation and intermediate structures during CVD of 2D materials have been proposed, [17][18][19][20][21][22][23] but to the best of our knowledge have not been studied experimentally. In general, kinetics and the thermochemistry of intermediate products, may lead to metastable structures.…”