Electrical control of nanoscale functionalization in graphene by the scanning probe technique

Ik-Su Byun,Inrok Hwang,Jong Wan Son,Wondong Kim,Hung Wei Shiu,Hyun-Joon Shin,Jin Sik Choi,Hyeonsik Cheong,Gwangtaek Oh,Bae Ho Park,Young-Woo Son,Danil W Boukhvalov,Chia-Hao Chen,Duhee Yoon,Jaeyoon Baik

doi:10.1038/am.2014.24

Abstract

Functionalized graphene is a versatile material that has well-known physical and chemical properties depending on functional groups and their coverage. However, selective control of functional groups on the nanoscale is hardly achievable by conventional methods utilizing chemical modifications. We demonstrate electrical control of nanoscale functionalization of graphene with the desired chemical coverage of a selective functional group by atomic force microscopy (AFM) lithography and their full recovery through moderate thermal treatments. Surprisingly, our controlled coverage of functional groups can reach 94.9% for oxygen and 49.0% for hydrogen, respectively, well beyond those achieved by conventional methods. This coverage is almost at the theoretical maximum, which is verified through scanning photoelectron microscope measurements as well as first-principles calculations. We believe that the present method is now ready to realize ‘chemical pencil drawing’ of atomically defined circuit devices on top of a monolayer of graphene.

Highlights

We demonstrate electrical control of nanoscale functionalization of graphene with the desired chemical coverage of a selective functional group by atomic force microscopy (AFM) lithography and their full recovery through moderate thermal treatments
Because functionalized graphene has distinguished physical[1] and chemical properties depending on functional groups[2] and their coverage,[3] it can be widely used for electronic,[4] chemical,[5] biological,[6] and optical[7] devices
Our results reveal that AFM lithography is a simple method to design graphene nanodevices with controlled hydrogen- or oxygen-containing functional groups

Summary

INTRODUCTION

Because functionalized graphene has distinguished physical[1] and chemical properties depending on functional groups[2] and their coverage,[3] it can be widely used for electronic,[4] chemical,[5] biological,[6] and optical[7] devices. It has been reported that atomic force microscopy (AFM) lithography[15] can provide suitable methods of nanoscale chemical modification on a pristine graphene without any conventional source of surface contamination such as poly (methyl methacrylate). If we verify the effect of voltage applied on derived functional groups during the modification, we can obtain an important tool to manipulate the chemical structures of modified graphene on the nanoscale with a controllable parameter. It is difficult to understand the local functional groups of modified graphene on the nanoscale[16] because the minimum analysis area ranges from 10 to 200 mm[2] (spot size).[17] A scanning photoelectron microscope (SPEM) equipped with scanning and focused X-ray of 200 nm[2] (spot size) is a powerful tool to investigate the local chemical structure.

D G D’ 10V

MATERIALS AND METHODS

RESULTS AND DISCUSSION