Schottky-Barrier-Controllable Graphene Electrode to Boost Rectification in Organic Vertical P-N Junction Photodiodes

Abstract

Monolayer graphene is used as an electrode to develop novel electronic device architectures that exploit the unique, atomically thin structure of the material with a low density of states at its charge neutrality point. For example, a single semiconductor layer stacked onto graphene can provide a semiconductor-electrode junction with a tunable injection barrier, which is the basis for a primitive transistor architecture known as the Schottky barrier field-effect transistor. This work demonstrates the next level of complexity in a vertical graphene-semiconductor architecture. Specifically, an organic vertical p-n junction (p-type pentacene/n-type N,N-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C-8)) on top of a graphene electrode constituting a novel gate-tunable photodiode device structure is fabricated. The model device confirms that controlling the Schottky barrier height at the pentacene-graphene junction can (i) suppress the dark current density and (ii) enhance the photocurrent of the device, both of which are critical to improve the performance of a photodiode.