Impact of Graphene Layer Thickness on Switching Speed of the Vertical Organic Field Effect Transistor

Vertical organic field effect transistor (VOFET) is very important to the future technologies owing to its fast switching speed, higher density on a chip and relatively low power consumption, and the potential to push the boundary of easy fabrication process based low cost flexible and biodegradable electronics. The incorporation of graphene in VOFET as a source electrode enhances the switching speed, when used in perforated manner. However, how the graphene layer thickness affects the switching speed of the organic field effect transistor in vertical geometry is still not clear. In this article, we simulate the graphene layer thickness dependence on the transfer characteristics of VOFETs, wherein n-type organic semiconductor N, N′-dioctyl-3, 4, 9, 10-perylenedicarboximide (PTCDI-C8) is taken as the active semiconductor channel, perforated graphene as a source electrode, and aluminium (Al) as a drain electrode. The results suggest that the variation in the graphene layer thickness has the impact on the switching speed, where ON/OFF ratio changed from 10⁶ to 10² from monolayer to 50 layers of graphene, respectively. The upsurge in the thickness increases the OFF current, while the ON current decreases and the transistor goes in saturation mode at even lower current density. The modification in graphene layer thickness changes the control of active channel and current modulation by the gate field, consequently the ON/OFF ratio value decreases. The findings will help in designing the perforated graphene source based VOFETs for improved switching speeds.