The effects of cationic molecules on graphene transistors

We investigated the electrical transport characteristics of graphene transistors functionalized with a self-assembled monolayer (SAM) of cationic molecules. Contact-opened, channel-opened, and pristine graphene transistors were fabricated, and the changes in their electronic transport properties upon SAM functionalization were investigated. All three types of devices undergo a negative shift in the Dirac charge neutrality point (CNP), with the variation of the contact-opened device larger than that of the channel-opened device. This observation confirms that contact electrodes dope graphene through their work function, and that the work functions of metal electrodes can be modulated through the introduction of cationic SAMs.