Recovering the Intrinsic Electrical Property of a Graphene Field-Effect Transistor by Interface Cleaning Technology

Because of the two-dimensional material, the graphenefield-effect transistor (GFET) is sensitive to the external environment.Surface contamination by photoresist residues originated from lithographyusually introduces extra scattering and uncontrolled hole doping,resulting in the modification of the intrinsic graphene electric properties.Here, we developed an interface cleaning technology to circumventthe photoresist residue problem, which is suitable for the large-scaleproduction of GFETs and is also compatible with the standard complementarymetal-oxide semiconductor (CMOS) process. Different from the traditionaltop-down fabricated GFETs, the source/drain electrodes were fabricatedon the substrate before the graphene film was transferred. This techniquecan avoid the photoresist residues in the metal electrode lithographyprocess and lead to the cleaner interface between graphene and thecontact metal. Subsequently, a removable Al layer was deposited onthe sample to protect the graphene channel from the photoresist residuesfor the further etching process. Benefiting from the clean and residue-freegraphene surface, the intrinsic characteristic of GFET with the Diracpoint near zero voltage was obtained, and the field-effect carriermobility was improved by 33%. Our surface clean method provides asimple way to enhance the electrical property of GFETs, which canbe used in the future very large-scale integration electronic applications.

Automated summary

Due to its susceptibility to external environmental factors, the graphene field-effect transistor (GFET) is affected by surface contamination from lithography residues. To address this issue, we developed an interface cleaning technology that is compatible with large-scale GFET production and the standard CMOS process. By fabricating the source/drain electrodes on the substrate before transferring the graphene film, we were able to avoid photoresist residues and achieve a cleaner interface, resulting in improved GFET performance.