title: Harnessing denatured protein for controllable bipolar doping of a monolayer graphene.
abstract: In this work, we demonstrated tunable p- and/or n-type doping of chemical vapor deposition-grown graphene with the use of protein bovine serum albumin (BSA) as a dopant. BSA undergoes protonation or deprotonation reaction subject to solution pH, thereby acting as either an electron donor or an electron acceptor on the graphene surface layered with denatured BSA through π-stacking interaction. This direct annealing of graphene with denatured BSA of amphoteric nature rendered facilitated fabrication of a p- and/or n-type graphene transistor by modulating pH-dependent net charges of the single dopant. Following AFM confirmation of the BSA/graphene interface assembly, the carrier transport properties of BSA-doped graphene transistors were assessed by I-V measurement and Raman spectra to show effective charge modulation of the graphene enabled by BSA doping at various pH conditions. The protein-mediated bipolar doping of graphene demonstrated in our work is simple, scalable, and straightforward; the proposed scheme is therefore expected to provide a useful alternative for fabricating graphene transistors of novel properties and promote their implementation in practice.
authors.affiliation: SKKU Advanced Institute of Nanotechnology (SAINT), §School of Chemical Engineering, and ∥College of Information and Communication Engineering, Sungkyunkwan University (SKKU) , Suwon 440-746, Korea.
authors.forename: Sung Kyu
authors.initials: SK
authors.lastname: Jang
authors.forename: Ji-Ryang
authors.initials: JR
authors.lastname: Jang
authors.forename: Woo-Seok
authors.initials: WS
authors.lastname: Choe
authors.forename: Sungjoo
authors.initials: S
authors.lastname: Lee
keywords: bipolar doping; graphene; heat-denaturation; protein