TY - JOUR
T1 - Grain Boundaries and Gas Barrier Property of Graphene Revealed by Dark-Field Optical Microscopy
AU - Ding, Dong
AU - Hibino, Hiroki
AU - Ago, Hiroki
N1 - Funding Information:
This work was supported by JSPS KAKENHI grant nos. JP15H03530, JP16H00917, and JP17K19036. We thank Y. Uchida for helping the EBSD measurement.
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2018/1/11
Y1 - 2018/1/11
N2 - We demonstrate that dark-field (DF) optical microscopy is a powerful tool to visualize grain boundaries (GBs) and grain structure of graphene grown by chemical vapor deposition (CVD). Copper oxide nanoparticles sparsely formed along the graphene GBs by postgrowth mild oxidation allow one to determine the position and structure of the GBs by the DF microscope. As DF imaging offers a much higher sensitivity than bright-field (BF) microscopy, some GBs were observed even without the postgrowth oxidation. We found that periodic Cu steps formed below graphene can be also used to visualize the grain structure of the as-grown graphene by DF microscopy. Moreover, DF imaging is applicable to study of the gas barrier property of CVD graphene. Interestingly, the dissolved oxygen inside Cu foil enhanced oxidation of the Cu surface below graphene in spite of the fact that the graphene protects the underlying Cu from the exterior gas. Our work highlights the wide availability of DF optical microscopy in characterizing graphene and related two-dimensional materials grown on metal substrates.
AB - We demonstrate that dark-field (DF) optical microscopy is a powerful tool to visualize grain boundaries (GBs) and grain structure of graphene grown by chemical vapor deposition (CVD). Copper oxide nanoparticles sparsely formed along the graphene GBs by postgrowth mild oxidation allow one to determine the position and structure of the GBs by the DF microscope. As DF imaging offers a much higher sensitivity than bright-field (BF) microscopy, some GBs were observed even without the postgrowth oxidation. We found that periodic Cu steps formed below graphene can be also used to visualize the grain structure of the as-grown graphene by DF microscopy. Moreover, DF imaging is applicable to study of the gas barrier property of CVD graphene. Interestingly, the dissolved oxygen inside Cu foil enhanced oxidation of the Cu surface below graphene in spite of the fact that the graphene protects the underlying Cu from the exterior gas. Our work highlights the wide availability of DF optical microscopy in characterizing graphene and related two-dimensional materials grown on metal substrates.
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U2 - 10.1021/acs.jpcc.7b10210
DO - 10.1021/acs.jpcc.7b10210
M3 - Article
AN - SCOPUS:85040518057
SN - 1932-7447
VL - 122
SP - 902
EP - 910
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 1
ER -