title: Tailoring the electrical properties of graphene layers by molecular doping.
abstract: It is an essential issue in graphene-based nanoelectronic and optoelectronic devices to tune the electrical properties of graphene layers, while preserving its unique band structure. Here, we report the tuning of electronic properties of single-, bi-, and trilayer mechanically exfoliated graphenes by p-toluenesulfonic acid (PTSA) molecular doping. Raman spectroscopy and charge transport measurements revealed that PTSA molecule imposes n-doping to single-, bi-, and trilayer graphenes. The shift of G and 2D peak frequencies and intensity ratio of single-, bi-, and trilayer graphenes are analyzed as a function of reaction time. The Dirac point is also analyzed as a function of reaction time indicates the n-type doping effect for all single-, bi-, and trilayer graphenes. Our study demonstrates that chemical modification is a simple approach to tailor the electrical properties of single-, bi-, and trilayer graphenes, while maintaining the important electrical assets.
authors.affiliation: Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747, Korea.
authors.forename: Arun Kumar
authors.initials: AK
authors.lastname: Singh
authors.forename: Muneer
authors.initials: M
authors.lastname: Ahmad
authors.forename: Vivek Kumar
authors.initials: VK
authors.lastname: Singh
authors.forename: Koo
authors.initials: K
authors.lastname: Shin
authors.forename: Yongho
authors.initials: Y
authors.lastname: Seo
authors.forename: Jonghwa
authors.initials: J
authors.lastname: Eom