Direct Chemical Vapor Deposition of Graphene on Dielectric Surfaces Ariel Ismach, †,‡ Clara Druzgalski, † Samuel Penwell, † Adam Schwartzberg, † Maxwell Zheng, †,‡ Ali Javey, †,‡ Jeffrey Bokor, †,‡ and Yuegang Zhang* ,† † The Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 and ‡ Electrical Engineering and Computer Science Department, University of California at Berkeley, Berkeley California 94720 ABSTRACT Direct deposition of graphene on various dielectric substrates is demonstrated using a single-step chemical vapor deposition process. Single-layer graphene is formed through surface catalytic decomposition of hydrocarbon precursors on thin copper films predeposited on dielectric substrates. The copper films dewet and evaporate during or immediately after graphene growth, resulting in graphene deposition directly on the bare dielectric substrates. Scanning Raman mapping and spectroscopy, scanning electron microscopy, and atomic force microscopy confirm the presence of continuous graphene layers on tens of micrometer square metal- free areas. The revealed growth mechanism opens new opportunities for deposition of higher quality graphene films on dielectric materials. KEYWORDS Graphene, CVD, nanoelectronics G raphene is a two-dimensional material that has been attracting extensive scientific interest. The existence of single-layer graphene was not considered possible until the recent achievement of the mechanical cleavage of highly ordered pyrolytic graphite (HOPG). 1 Since then, the extraordinary electronic properties of graphene, such as ballistic transport over ∼0.4 μm length, 1 high electron mobility, 1 quantum-hall effect at room temperature, 2,3 and single-molecule field-effect sensitivity, 4 have been experi- mentally observed. Semiconducting graphene nanoribbons have also been fabricated to demonstrate the high perfor- mance of graphene field-effect transistors. 5,6 Application of graphene-based devices utilizing its superior electronic prop- erties, however, requires a method of forming uniform single-layer graphene film on dielectric substrates on a large scale. The mechanical cleavage method can only lead to small areas covered with graphene and is thus not suitable for large-scale fabrication processes. The ultrahigh vacuum annealing of single-crystal SiC (0001) 7,8 may lead to better coverage but with relatively small domain size and requiring expensive materials and equipment. Continuous films have been achieved by chemical routes, such as deposition from solution-based exfoliated graphite 9,10 and graphite oxide. 11,12 Such approaches, however, lack control of the number of graphene layers and exhibit deteriorated transport proper- ties. Catalytic chemical vapor deposition (CVD) on single- crystal transition metals has also been shown to lead to relatively high coverage of high quality graphene. 13-16 However, the expensive substrates inhibit the use of this method in large-scale processes. Recently, less expensive and more accessible methods for CVD synthesis of high quality large area graphene were demonstrated using poly- crystalline nickel films 17,18 and copper foils 19,20 or copper film. 21 The graphene film could be transferred to various substrates after etching off the metals. 17-20 A non-CVD synthesis of relatively large number of graphene layers (mainly 5-10 layers) was also achieved by dissolution of a solid carbon source in a nickel film and subsequent segrega- tion of graphene on a silion dioxide substrate. 22 Use of metal with high carbon solubility such as nickel, however, normally has difficulty to control the number of graphene layers, no matter if the method is based on CVD 17,18 or solid state diffusion. 22 A method for direct CVD growth of only few- graphene layers on nonconducting materials is much needed for future electronic and optical applications. The study of such direct deposition process is also scientifically intriguing for understanding the graphene CVD growth mechanism. Here we present a method for the direct chemical vapor deposition of a single- or few-layer graphene film on dielec- tric surfaces via a sacrificial copper film. Following recent reports, we have been working on the CVD growth of graphene on metals, 17,18,20 and on micrometer-thick copper foils in particular, noticing that a significant amount of the copper evaporates and deposits at the edges of the fused silica tube used in the CVD (see SI for growth methods). Considering the melting temperature of the copper, ∼1084 °C, along with the high temperature during the growth, ∼1000 °C, and the low pressure in the chamber, 100-500 mTorr, the significant evaporation of the metal is not surprising. Based on this observation, we propose a mech- anism for in situ graphene deposition on insulating surfaces by a controlled metal evaporation from the surfaces during, or immediately after, the catalytic growth (Figure 1). The use * To whom correspondence should be addressed. E-mail: yzhang5@lbl.gov. Received for review: 08/31/2009 Published on Web: 04/02/2010 pubs.acs.org/NanoLett © 2010 American Chemical Society 1542 DOI: 10.1021/nl9037714 | Nano Lett. 2010, 10, 1542–1548