Revealing the grain structure of graphene grown by chemical vapor deposition

Abstract

The physical processes occurring in the presence of disorder: point defects, grain boundaries, etc. may have detrimental effects on the electronic properties of graphene. Here we present an approach to reveal the grain structure of graphene by the selective oxidation of defects and subsequent atomic force microscopy analysis. This technique offers a quick and easy alternative to different electron microscopy and diffraction methods and may be used to give quick feedback on the quality of graphene samples grown by chemical vapor deposition.

Single-step deposition of high-mobility graphene at reduced temperatures

“…High-resolution (B1 nm) atomic force microscopy and SEM studies over multiple (100 Â 100) mm 2 areas of an annealed monolayer graphene sample 22 , which was transferred to single crystalline sapphire with a polymer-free technique 23 , indicated no discernible grain boundaries. With an increase of growth time, small adlayers began to develop on top of the first layer in an aligned manner, as exemplified by the SEM images in Fig.…”

Polycrystalline graphene and other two-dimensional materials

“…Using optical microscopy, one can also enhance the contrast of grains and make GBs more visible by taking advantage of the more effective oxidation of substrate (Cu) in the region exposed or under GBs (which can be further functionalized to facilitate oxidation) 97,98 . Similar techniques can also be used to facilitate AFM and other types of GB imaging 99 . Beyond standard optical imaging, GBs can be easily visualized using spectroscopic Raman imaging of the defect-activated D mode (~1,350 cm -1 ) 76,97 .…”

Charge and Spin Transport in Disordered Graphene-Based Materials

“…This has been confirmed in several experiments [28,18]. By using the numerical simulations we report on the role played by chemical adsorbates on grain boundaries in charge transport in Chapter 4…”

“…4.20a), where oxygen atoms preferentially attach to the non-hexagonal sites located in the GGBs. Selective oxidation of GGBs can be demonstrated by transferring CVD graphene to a mica substrate and heating the sample for 30 minutes at 500 o C. This process selectively burns away the GGBs, [28] giving access to the grain morphology within the samples with AFM. A representative AFM image is given in Fig.…”

“…[18,28,194] One approach involves the use of an oxidizing agent to selectively oxidize copper underneath the GGBs. [18] Fig.…”