Novel fabrication of graphene sheets from self-assembled monolayer and polymer thin films

Abstract

Graphene, a two dimensional crystalline monolayer sheet of sp2-bonded carbon atoms arranged in a honeycomb lattice, has been highly attracting interests after being revealed its outstanding electronic, mechanical, and chemical properties since it was generated for the first time experimentally through mechanical exfoliation (“scotch tape” method). Not only that, its highly conductivity, transparency, flexibility and high-temperature stability have made graphene one of the excellent candidates for replacing ITO as flexible electronic electrodes.A variety of methods relating with fabrication of graphene sheets are studied so far and such of those can be divided into two main categories

exfoliations and epitaxials. Each of approaches is classified into several methods as well. In terms of exfoliation methods, besides above mentioned mechanical exfoliation, chemical exfoliation is widely used because it is inexpensive and do not need process of transferring the graphene from the growth substrates to other ones. However, graphene films produced are limited to small sizes (mostly < 1000 ┢m) due to the films are fabricated mainly from graphite, which is not scalable technique. On the other hand, epitaxial approaches are those that utilize substrates such as SiC or metal catalytic substrates, nickel or copper, for direct growth of graphene. However, even though some of these methods are possible to provide large-scale size of graphene, the uniformity of graphene surface is not consistent so that multilayered graphene is yielded. Not only that, gases used in CVD-grown method are dangerous In this research, we tried unprecedented way to generate graphene sheets from electron beam irradiated self-assembled monolayer molecules (SAMs) while heating them simultaneously and from polymer thin films pyrolyzing under high temperature conditions. With these manner, we expected that there are some advantages since polymers are cost-effective, and polymers themselves can be performed various process approaches, that is to say, graphenes produced from SAMs and polymers are controllable in many different ways as well.To make sure whether the SAMs and polymers are changed to graphene, we mainly analyzed them using Raman spectroscopy. As a results, in the case of polymer thin films, most of them turned into a few layers of graphene when metal capping layer was deposited atop their surface. On the other hand, experiment using SAMs was not effective completely, however, it does not seemed that the trial was useless in terms of surface change of heated SAMs at certain temperatures.