Wafer Scale Homogeneous Bilayer Graphene Films by Chemical Vapor Deposition

TL;DR

This paper reports the successful synthesis of large-area, homogeneous bilayer graphene films over 2-inch scales via chemical vapor deposition, enabling potential semiconductor applications.

Contribution

It demonstrates a scalable method for producing wafer-scale bilayer graphene with over 99% coverage and verified bilayer properties.

Findings

Over 99% bilayer coverage confirmed by Raman spectroscopy

Bandgap opening observed in 98% of dual-gate transistors

Homogeneous bilayer graphene synthesized on copper foil

Abstract

The discovery of electric field induced bandgap opening in bilayer graphene opens new door for making semiconducting graphene without aggressive size scaling or using expensive substrates. However, bilayer graphene samples have been limited to um size scale thus far, and synthesis of wafer scale bilayer graphene posts tremendous challenge. Here we report homogeneous bilayer graphene films over at least 2 inch x 2 inch area, synthesized by chemical vapor deposition on copper foil and subsequently transferred to arbitrary substrates. The bilayer nature of graphene film is verified by Raman spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM). Importantly, spatially resolved Raman spectroscopy confirms a bilayer coverage of over 99%. The homogeneity of the film is further supported by electrical transport measurements on dual-gate bilayer graphene transistors, in which bandgap opening is observed in 98% of the devices.