Uniform large-scale fabrication of graphene thin films with controllable thickness represents a key challenge for integration of graphene into practical electronic devices. Recently, graphene of high quality has been synthesized by chemical vapor deposition (CVD) on transition metal catalysts [1,2]. The graphene growth by CVD on polycrystalline copper [2] is particularly interesting because it allows single graphene layer over 95% of the surface and the residual 5% is covered by 2-3 layered graphene film. Hence, this is the first [2] reported reproducible method to synthesize uniform graphene thickness over large area. Then the as grown graphene can be transferred by different processes, onto a variety of substrates. An appealing challenge is to selectively obtain different graphene thicknesses over large area, to satisfy different applications. Here we report a detailed study of the multilayer graphene domains that appear in limited regions of the copper surface. The lateral size as well as the graphene thickness and stacking order, has been carefully investigated as a function of copper pre-treatment and growth parameters. In particular the role of the feed stock gas pressure and ratio between the etching gas (H2) and the precursor (CH4) has been demonstrated to affect the lateral size and the thickness. Optoelectronic properties of the transferred graphene films onto SiO2 are also presented.

References

1. K. S. Kim, Y. Zhao, H. Jang, S. Y. Lee, J. M. Kim, K. S. Kim, J. H. Ahn, P. Kim, J. Y. Choi and B. H. Hong, Nature 457, 706 (2009).

2. X. Li, W. Cai, J. An, S. Kim, J. Nah, D. Yang, R. Piner, A. Velamakanni, I. Jung, E. Tutuc, S. K. Banerjee, L. Colombo, and R. S. Ruoff, Science 324, 1312 (2009).