Decreasing Graphene Contact Resistance by Increasing Edge Contact Length

Abstract

Graphene is a two dimensional material which has combination of unique mechanical, electrical and optical properties. Due to the unique properties of graphene, it has potential for several applications such as radio frequency applications and ultrafast photodetectors. Reducing contact resistance of metal-graphene is important for further improvement of graphene devices and for realization of graphene based electronics. Contact between graphene and metal can be improved by edge contact length. Edge contact length improves coupling between metal and graphene; therefore, contact resistance is reduced. Edge contact length can be introduced by generating nanostructures under metal. Fabrication of graphene based devices requires special treatment due to graphene‟s two dimensional natures. In this thesis, fabrication process for graphene devices is discussed in details. Main attention is given to reducing contact resistance. The fabrication process includes e-beam lithography; choosing right metals and metallization techniques; etching of graphene; lift-off issues; and reducing resist residues. In this research, graphene under the metal contacts was patterned by electron beam lithography with series of holes of 100nm to 300nm radius etched by oxygen plasma etching. The holes were patterned by electron beam lithography, and metallization was carried out by electron beam evaporation followed by lift-off process. The effects of the geometrical parameters of the holes and different graphene length under the metal are investigated experimentally. This research can be used as source of graphene device fabrication for the beginners.