走査トンネル顕微鏡を用いた単層酸化グラフェンのナノスケール観察;走査トンネル顕微鏡を用いた単層酸化グラフェンのナノスケール観察;Nanoscale Observation of a Single Graphene Oxide layer Using Scanning Tunneling Microscopy

Nano-scale structures of a single graphene oxide (GO) layer deposited on Au(111) covered with the octanethiolate self-assembled monolayer (C8S-SAM) have been investigated by scanning tunneling microscopy (STM). Using a spin-coating method, we found that GO ‰akes are isolated and are dispersed on the C8S-SAM/Au(111) surface whereas these are likely to pile up on the bare Au(111) surface. Furthermore, the C8S-SAM formed on Au(111) enables us to deposit GO keeping the surface clean even if we prepared the sample in the atmosphere. By using the C8S-SAM/Au(111) substrate, we succeeded in observing an STM image of the unreduced GO. The STM image of a single GO layer exhibits the grain-like structure having the range in height from 0.6 to 1.1 nm. The biasdependent STM study indicated that the STM image of GO is stably and reproducibly obtained at the voltage where the density of states of GO exists.