Although graphene has been successfully grown in large scale via chemical vapor deposition (CVD), it is still questionable whether the mechanical properties of CVD graphene are equivalent to those of exfoliated graphene. In addition, there has been an issue regarding how the tilt angle of the grain boundary (GB) affects the strength of graphene. We investigate the mechanical properties of CVD graphene with nanoindentation from atomic force microscopy and transmission electron microscopy. Surprisingly, the samples with GB angles of 10° and 26° yielded similar fracture stresses of ~ 80 and ~ 79 GPa, respectively. Even for samples with GB exhibiting a wider range, from 0° to 30°, only a slightly wider fracture stress range (~ 50 to ~ 90 GPa) was measured, regardless of tilt angle. The results are contrary to previous studies that have reported that GBs with a larger tilt angle yield stronger graphene film. Such a lack of angle dependence of GB can be attributed to irregular and well-stitched GB structures.
Bibliographical noteFunding Information:
This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. 20173010013340). The authors also acknowledge support from Samsung Research Funding Center of Samsung Electronics (Project Number SRFC-MA1502-12) and Basic Science Research Program (2016M3A7B4910940)) through the National Research Foundation (NRF) of Korea funded by the Ministry of Science, ICT & Future Planning.
All Science Journal Classification (ASJC) codes
- Ceramics and Composites