Fabrication of Graphene p-n Junction Field Effect Transistors on Patterned Self-Assembled Monolayers/Substrate

Abstract

The field-effect transistors (FETs) with a graphene-based p-n junction channel were fabricated using the patterned self-assembled monolayers (SAMs). The self-assembled 3-aminopropyltriethoxysilane (APTES) monolayer deposited on SiO 2 /Si substrate was patterned by hydrogen plasma using selective coating poly-methylmethacrylate (PMMA) as mask. The APTES-SAMS on the SiO 2 surface were patterned using selective coating of PMMA. The APTES-SAMs of the region uncovered with PMMA was removed by hydrogen plasma. The graphene synthesized by thermal chemical vapor deposition was transferred onto the patterned APTES-SAM/SiO 2 substrate. Both p-type and n-type graphene on the patterned SAM/SiO 2 substrate were fabricated. The graphene-based p-n junction was studied using Raman spectroscopy and X-ray photoelectron spectroscopy. To implement low voltage operation device, via ionic liquid (BmimPF 6 ) gate dielectric material, graphene-based p-n junction field effect transistors was fabricated, showing two significant separated Dirac points as a signature for formation of a p-n junction in the graphene channel.

Lattice Transparency of Graphene

“…The “electron transfer-transparency” of graphene has also been reported, and this property accounts for redox reactions that occur at the graphene surface even though graphene itself is neither an oxidizing nor reducing agent . Other examples of the transparency of graphene have been found in interface engineering studies of graphene, including the engineering of its chemical reactivity carried out by deploying substrates that bind to its surface, − and the delicate tailoring of the electrical properties of its devices by engineering the substrate. − It is generally accepted that such substrate sensitivity of graphene devices is originated from the amount of charge impurities in the substrate that induce electron–hole puddles in the graphene. ,, Basically, all of the features that occur via the transmission of the surface properties of the substrate are based upon graphene’s one atom thickness; thus, these phenomena can be thought of as “tunneling of a given atomic scale electrostatic field” through graphene.…”

Simple Interface Engineering of Graphene Transistors with Hydrophobizing Stamps

“…Furthermore, SAM-induced interface engineering is not only useful for enhancing the performance of graphene devices, but also could be used for various electronic applications. For example, p–n junction devices using SAM-based interface engineering and the possibility of spatially controlling graphene functionalization by patterning the substrate with a SAM have been reported. Despite the above-mentioned advantages, SAM-based interface engineering may not ensure the long-term stability of a graphene device because SAM molecules may degrade in ambient conditions …”