Fabrication of self-organized and lithographic graphene ribbons grown on SiC

Bi-Yi Wu^1,2*, Yanfei Yang¹, Albert Rigosi¹, Jiuning Hu¹, Hsin-Yen Lee¹, Mattias Kruskopf¹, Hanbyul Jin¹, Randolph Elmquist¹, Chi-Te Liang²

¹National Institute of Standards and Technology, Maryland, USA
²National Taiwan University, Taipei, Taiwan

* Presenter:Bi-Yi Wu, email:x6339109@gmail.com

It has been shown that the edge properties play an important role in transport in narrow ribbons. In this work, we prepare two types of graphene ribbons with vastly different fabrication techniques to discuss the edge effects. The widths of samples are within a few hundred nm. The first type of samples is made by electron-beam lithography and conventional RIE etching processes. Strong negative magnetoresistance (MR) behavior is observed as expected due to irregular edges, the consequence of disorder in the edge structure (e.g. chemical dopants, the resolution of e-beam lithography and so on). The second type of graphene ribbons on SiC is self-organized, and grown “naturally” (i.e. similar to the way large-area monolayer graphene can be prepared by high-temperature Si sublimation [1,2]), which guarantees cleaner and more uniform edges. At low magnetic fields, the MR curve shows evidence for weak localization due to intervalley scattering from the sharp edges. With increasing magnetic field, quantum transport described by boundary scattering in the quasi-ballistic regime can be observed [3]. At even higher magnetic fields, classical scattering dominates because the quantum transport is destroyed. The scattering mechanism of self-organized ribbons is totally different from that of the etched one due to the edge effects.

References
[1] T. Ohta et al., Phys. Rev. B 81, 121411(R) ( 2010).
[2] C. Berger et al., J. Phys. Chem. 108, 19912 (2004).
[3] T. J. Thornton et al., Phys. Rev. Lett. 63, 2128 (1989).

Keywords: self-organized graphene, boundary scattering