Perforated graphene source electrode for improved subthreshold swing and miniaturization of vertical organic field effect transistors (VOFET)

Vertical organic field effect transistors surpass their counterpart lateral organic field effect transistors in switching speed, reduced power consumption, and miniaturization control. The active channel length can be reduced to sub 100 nm easily without any sophisticated lithographic process in VOFETs. Further, to reduce the dimension of the VOFET, atomic thin graphene layer with excellent mobility can be considered as source electrode. However, to avoid gate field screening by graphene, perforation in graphene is desired. We have systematically simulate the effect of perforation size in graphene electrode on the improvement of the transfer characteristics of the VOFET with an n-type organic semiconductor N, N'-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) as an active channel material, while aluminum as a drain electrode. We found that the perforation size has an impact on the subthreshold swing (SS) of the device, which controls the device on/off speed. SS is also affected by the length of the active channel and source electrode width. 50 nm perforated size, and 50 nm active channel length showed the best switching speed, while unperforated graphene had 10 nm size. The obtained results might be useful in designing next generation organic transistors for improved performances.