Hindawi Publishing Corporation Journal of Nanomaterials Volume 2013, Article ID 393724, 6 pages http://dx.doi.org/10.1155/2013/393724 Research Article Effect of Catalyst Morphology on the Quality of CVD Grown Graphene Ya-Ping Hsieh, 1 Yi-Wen Wang, 1 Chu-Chi Ting, 1 Hsiang-Chen Wang, 1 Kuang-Yao Chen, 2 and Chang-Chung Yang 2 1 Graduate Institute of Opto-Mechatronics, National Chung Cheng University, 168 University Road, Min-Hsiung, Chiayi 62102, Taiwan 2 Green Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan Correspondence should be addressed to Ya-Ping Hsieh; yphsieh@ccu.edu.tw Received 15 March 2013; Revised 9 July 2013; Accepted 17 July 2013 Academic Editor: Nadya Mason Copyright © 2013 Ya-Ping Hsieh et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. he strong interest in graphene has motivated large efort in the scalable production of high-quality material. he potential of chemical vapor deposition on Cu foil to produce such graphene is impeded by lacking understanding of the relation between catalyst properties and graphene performance. We here present a systematic analysis of the catalyst morphology and its efect on electrical properties of graphene. We ind that nanometer sized particles increase the density of bilayer regions but have no signiicant efect on carrier transport. Long wavelength roughness (waviness), on the other hand, generates defective graphitic regions that deteriorate carrier mobility. hese indings shed light on the graphene formation process on Cu substrates and open a route to improve graphene quality for electronics applications. 1. Introduction Graphene, a single atomic layer of carbon atoms, has gen- erated enormous attention due to its physical properties. Proof-of-concept experiments demonstrated novel electronic and optoelectronic devices in transistors [1], solar cells [2, 3], photodetectors [4], and so forth. he desire for large-scale application of this material has motivated the development of a number of methods to synthesize large-area graphene sheets. Amongst these approaches, the chemical vapor depo- sition (CVD) synthesis of graphene on Cu substrate [5, 6] has shown great promise for producing high-quality single- layer graphene. Despite signiicant eforts, the properties of CVD graphene have yet to reach the requirements of electronics applications for mobility and uniformity. Recent reports emphasize the importance of the surface morphology of the catalytic Cu substrate in determining the homogeneity and electronic transport properties of the grown graphene ilm [7–9]. It was found that imperfections in the Cu substrate interfere with graphene growth. Furthermore, commonly used Cu foil is usually covered with a layer of chromium oxide for anticorrosion protection [10] that can afect the properties of grown graphene. Consequently, the formation of smooth Cu surfaces free of contaminants becomes a necessary step for the synthesis of high-quality graphene. Despite this importance of the catalyst pretreatment, little work has been done to correlate the condition of the Cu catalyst with the properties of the obtained graphene. We here present the irst systematic study of the efect of catalyst morphology on the electrical and optical properties of graphene. We ind that a higher density of surface particles supports the formation of bilayer graphene regions but has little efect on the electrical properties of the graphene ilm. Low frequency roughness (waviness), on the other hand, deteriorates the quality of graphene signiicantly as studied by Raman spectroscopy and electrical measurements. hese observations provide deeper understanding of the graphene growth and have large signiicance for the optimization of graphene quality for future applications.