High-Yield Assembly of Graphene Field-Effect Transistors under a Non-Uniform Electric Field

Abstract

Intriguing properties of graphene such as high carrier mobility, large surface area, and high thermal conductivity, and superior optical transmittance make it very promising for a lot of applications including field-effect transistors (FETs), chemical sensors, solar-cells and light-emitting diodes, 1‐4 where a large quantity production of high quality graphene is very important for its implementation. Graphene canbeobtainedbymanymethodsincludingthemechanical/chemical exfoliation, epitaxial growth on SiC or Cu foil, reduction of graphene oxide (GO). 5 Among them, reduced graphene oxide (rGO) has been intensivelyinvestigatedbecausealargeamountofgrapheneflakescan be produced. 6‐8 Also, a method for high-yield production of graphene dispersions has been demonstrated by exfoliating the graphite in organic solvents. 8,9 However, the properties of rGO are still not as good as those of the pristine graphene due to the functional groups, insufficient reduction, and point defects created during the chemical processes. 10,11 In our experiments, graphene flakes were obtained by sonicating three-dimensional (3-D) graphene foam because a large amount of graphene flakes with good conductivity and carrier mobility can be produced without complex chemical processes. 3-D graphene foam, which is grown by the chemical vapor deposition (CVD) method, is a fascinating material due to its superior properties such as large surface-to-volume ratio, high conductivity and carrier mobility. Therefore, the graphene flakes which are obtained from 3-D graphene foam have a great potential for graphene-based electronic