title: One-step formation of a single atomic-layer transistor by the selective fluorination of a graphene film.
abstract: In this study, the scalable and one-step fabrication of single atomic-layer transistors is demonstrated by the selective fluorination of graphene using a low-damage CF4 plasma treatment, where the generated F-radicals preferentially fluorinated the graphene at low temperature (<200 °C) while defect formation was suppressed by screening out the effect of ion damage. The chemical structure of the C-F bonds is well correlated with their optical and electrical properties in fluorinated graphene, as determined by X-ray photoelectron spectroscopy, Raman spectroscopy, and optical and electrical characterizations. The electrical conductivity of the resultant fluorinated graphene (F-graphene) was demonstrated to be in the range between 1.6 kΩ/sq and 1 MΩ/sq by adjusting the stoichiometric ratio of C/F in the range between 27.4 and 5.6, respectively. Moreover, a unique heterojunction structure of semi-metal/semiconductor/insulator can be directly formed in a single layer of graphene using a one-step fluorination process by introducing a Au thin-film as a buffer layer. With this heterojunction structure, it would be possible to fabricate transistors in a single graphene film via a one-step fluorination process, in which pristine graphene, partial F-graphene, and highly F-graphene serve as the source/drain contacts, the channel, and the channel isolation in a transistor, respectively. The demonstrated graphene transistor exhibits an on-off ratio above 10, which is 3-fold higher than that of devices made from pristine graphene. This efficient transistor fabrication method produces electrical heterojunctions of graphene over a large area and with selective patterning, providing the potential for the integration of electronics down to the single atomic-layer scale.
authors: Department of Electronic Engineering, Chang Gung University, Tao-Yuan, 333, Taiwan.
authors: Kuan-I
authors: KI
authors: Ho
authors: Jia-Hong
authors: JH
authors: Liao
authors: Chi-Hsien
authors: CH
authors: Huang
authors: Chang-Lung
authors: CL
authors: Hsu
authors: Wenjing
authors: W
authors: Zhang
authors: Ang-Yu
authors: AY
authors: Lu
authors: Lain-Jong
authors: LJ
authors: Li
authors: Chao-Sung
authors: CS
authors: Lai
authors: Ching-Yuan
authors: CY
authors: Su
keywords: CF4 plasma; fluorinated graphene; graphene; transistors