title: N-doped graphene field-effect transistors with enhanced electron mobility and air-stability.
abstract: Although graphene can be easily p-doped by various adsorbates, developing stable n-doped graphene that is very useful for practical device applications is a difficult challenge. We investigated the doping effect of solution-processed (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)dimethylamine (N-DMBI) on chemical-vapor-deposited (CVD) graphene. Strong n-type doping is confirmed by Raman spectroscopy and the electrical transport characteristics of graphene field-effect transistors. The strong n-type doping effect shifts the Dirac point to around -140 V. Appropriate annealing at a low temperature of 80 ºC enables an enhanced electron mobility of 1150 cm(2) V(-1) s(-1). The work function and its uniformity on a large scale (1.2 mm × 1.2 mm) of the doped surface are evaluated using ultraviolet photoelectron spectroscopy and Kelvin probe mapping. Stable electrical properties are observed in a device aged in air for more than one month.
authors.affiliation: Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, 790-784, Republic of Korea.
authors.forename: Wentao
authors.initials: W
authors.lastname: Xu
authors.forename: Tae-Seok
authors.initials: TS
authors.lastname: Lim
authors.forename: Hong-Kyu
authors.initials: HK
authors.lastname: Seo
authors.forename: Sung-Yong
authors.initials: SY
authors.lastname: Min
authors.forename: Himchan
authors.initials: H
authors.lastname: Cho
authors.forename: Min-Ho
authors.initials: MH
authors.lastname: Park
authors.forename: Young-Hoon
authors.initials: YH
authors.lastname: Kim
authors.forename: Tae-Woo
authors.initials: TW
authors.lastname: Lee
keywords: carrier mobility; dirac point; graphene field-effect transistor; n-type doping