New record on the growth of graphene single crystals

April 02, 2019

Graphene, especially the graphene single crystal is a star material for the future photonics and electronics due to their unique properties, such as giant intrinsic charge carrier mobility, record thermal conductivity, super stiffness and excellent light transmission. However, whether graphene can live up to the expectation depends on the reliable high-quality synthesis with high efficiency. The fabrication methodology of graphene has been prospering in the past years.

Recently, one research group from Wuhan University, China explored the exciting rapid growth of large graphene single crystal on liquid Cu with the rate up to 79 μm s-1 in Science China Materials (DOI: 10.1007/s40843-019-9406-7) based on the liquid metal chemical vapor deposition strategy.

Prof. Lei Fu stated: "the natural property of liquid metal qualifies it to be an ideal platform for the low-density nucleation and the fast growth of graphene. Liquid metal catalyst possesses quasi-atomically smooth surface with high diffusion rate, which can avoid the defects and grain boundaries that are inevitable on solid metal. The rich free electrons in liquid Cu accelerate the nucleation of graphene, realizing the nucleation of graphene single crystal within seconds. And in the meantime, the isotropic smooth surface greatly suppresses the nucleation density. Moreover, the fast mass transfer of carbon atoms due to the excellent fluidity of liquid Cu promotes the fast growth."

They systematically studied the nucleation and growth behavior of graphene on solid Cu and liquid Cu. As a comparison with solid Cu, the nucleation density of graphene on liquid Cu exhibits a strong decline and the related activation energy also declines. As for the growth rate, the growth rate of graphene on liquid Cu is almost two orders larger compared to that on solid Cu. In order to elucidate the growth kinetics of the growth of graphene on liquid Cu, they employed carbon isotope labeling Raman spectra and time of flight secondary ion mass spectra to trace the distribution of carbon atoms in liquid Cu. It can be found that 13C and 12C atoms uniformly mix in each graphene single crystal and a certain amount of carbon atoms can be detected in the bulk of liquid Cu, compared to the situation in solid Cu with extremely low carbon solubility. Unlike the surface adsorption growth mode on solid Cu, the precursor supply for the graphene growth on liquid Cu can both come from the surface adsorption and the bulk segregation. This can be attributed to the rich vacancies in liquid Cu, in which carbon atoms can firstly diffuse into the metal bulk before segregating and precipitating toward the Cu surface. The binary contributions of the precursor supply, i.e., the surface adsorption and the bulk segregation, accelerate the fast growth of graphene.

"We think the study on the growth speed of graphene in liquid Cu system will enrich the research map of the growth of two-dimensional (2D) materials on liquid metal," says Prof. Lei Fu. "More interesting and unique behaviors in the liquid surface are to be discovered. The liquid metal strategy for the rapid growth of graphene will hopefully be extended to various 2D materials and thus promote their future applications."
This research was funded by the National Natural Science Foundation of China (21673161) and the Sino-German Center for Research Promotion (1400).

See the article: Shuting Zheng, Mengqi Zeng, Hui Cao, Tao Zhang, Xiaowen Gao, Yao Xiao and Lei Fu, "Insight into the rapid growth of graphene single crystals on liquid metal via chemical vapor deposition" , Science China Materials. doi: 10.1007/s40843-019-9406-7

Science China Press

Related Graphene Articles from Brightsurf:

How to stack graphene up to four layers
IBS research team reports a novel method to grow multi-layered, single-crystalline graphene with a selected stacking order in a wafer scale.

Graphene-Adsorbate van der Waals bonding memory inspires 'smart' graphene sensors
Electric field modulation of the graphene-adsorbate interaction induces unique van der Waals (vdW) bonding which were previously assumed to be randomized by thermal energy after the electric field is turned off.

Graphene: It is all about the toppings
The way graphene interacts with other materials depends on how these materials are brought into contact with the graphene.

Discovery of graphene switch
Researchers at Japan Advanced Institute of Science and Technology (JAIST) successfully developed the special in-situ transmission electron microscope technique to measure the current-voltage curve of graphene nanoribbon (GNR) with observing the edge structure and found that the electrical conductance of narrow GNRs with a zigzag edge structure abruptly increased above the critical bias voltage, indicating that which they are expected to be applied to switching devices, which are the smallest in the world.

New 'brick' for nanotechnology: Graphene Nanomesh
Researchers at Japan advanced institute of science and technology (JAIST) successfully fabricated suspended graphene nanomesh (GNM) by using the focused helium ion beam technology.

Flatter graphene, faster electrons
Scientists from the Swiss Nanoscience Institute and the Department of Physics at the University of Basel developed a technique to flatten corrugations in graphene layers.

Graphene Flagship publishes handbook of graphene manufacturing
The EU-funded research project Graphene Flagship has published a comprehensive guide explaining how to produce and process graphene and related materials (GRMs).

How to induce magnetism in graphene
Graphene, a two-dimensional structure made of carbon, is a material with excellent mechani-cal, electronic and optical properties.

Graphene: The more you bend it, the softer it gets
New research by engineers at the University of Illinois combines atomic-scale experimentation with computer modeling to determine how much energy it takes to bend multilayer graphene -- a question that has eluded scientists since graphene was first isolated.

How do you know it's perfect graphene?
Scientists at the US Department of Energy's Ames Laboratory have discovered an indicator that reliably demonstrates a sample's high quality, and it was one that was hiding in plain sight for decades.

Read More: Graphene News and Graphene Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to