Single-walled carbon nanotubes have been studied as channel regions of thin film transistors due to their excellent electrical properties such as variable electron bandgap, high mobility, and high-speed charge transport. However, electrical performance and applications were limited by the contact resistance in the contact area between the metal electrode and the single-walled carbon nanotube channel. Therefore, in this study, we tried to reduce the contact resistance through two methods. The first was changed to the edge contact structure which contacted with side-to-side from the top contact structure which contacted with up-down. The contact length can be close to zero because the contact between the channel and the electrode made as a dot. At this time, the single-walled carbon nanotubes were encapsulated by hexagonal boron nitride to further increase the output current. The second is the contact between carbon nanotubes and graphene, which are homogeneous carbon-based materials, rather than the contact between common metal materials and carbon nanotubes.
The graphene electrode showed ohmic contact characteristics in which the output current changes linearly according to the drain voltage, unlike the gold electrode having the Schottky contact property. The graphene electrode also showed an excellent current level of about $30 \muA$ at 1 V drain voltage. In conclusion, this study first formed edge contact between the carbon nanotube channels and the graphene electrodes, showing significant insights into the edge contact between carbon-based materials.