AVS 62nd International Symposium & Exhibition
    2D Materials Focus Topic Monday Sessions
       Session 2D+EM+NS+PS+SP+SS+TF-MoM

Paper 2D+EM+NS+PS+SP+SS+TF-MoM2
Effect of Surface Termination on the Growth of Graphene on Cu Single Crystal Substrates

Monday, October 19, 2015, 8:40 am, Room 212C

Session: 2D Materials: Growth and Fabrication
Presenter: Tyler Mowll, University at Albany-SUNY
Authors: T.R. Mowll, University at Albany-SUNY
E.W. Ong, University at Albany-SUNY
P. Tyagi, GLOBALFOUNDRIES
Z.R. Robinson, College at Brockport-SUNY
C.A. Ventrice, Jr., SUNY Polytechnic Institute
Correspondent: Click to Email
The most common technique for synthesizing single-layer graphene films with large lateral dimensions is chemical vapor deposition (CVD) on Cu foil substrates. The primary reasons for choosing Cu substrates are the extremely low solubility of carbon in Cu, which allows a self-limited growth of graphene, and the relatively low cost of the Cu foil substrates. However, the transport properties of the CVD grown graphene films are typically a couple of orders of magnitude lower than for graphene flakes mechanically exfoliated from graphite. One of the reasons for the reduction in transport properties is the presence of crystalline defects in the CVD grown films. These structural defects arise in part from the multidomain structure of the Cu films. In order to achieve a better understanding of the influence of the surface termination of the Cu substrate on the crystallization of graphene during the CVD growth process, a systematic study of graphene growth on Cu(100), Cu(110), and Cu(111) crystals has been performed. The growth process is performed in an ultra-high vacuum (UHV) chamber that has been modified to perform CVD growth at pressures as high as 100 mTorr. The precursor gas used is ethylene. This growth procedure allows for the preparation of the clean surfaces in UHV, growth under typical CVD conditions, and characterization of the surface structure in UHV, without exposing the sample to atmospheric contaminants. Our results indicate that the Cu(111) surface has the lowest catalytic activity of the three surfaces for the decomposition of ethylene. In fact, the decomposition rate is so low that graphene growth is suppressed because of the sublimation of Cu at the elevated temperatures used to grow the graphene. By using an Ar overpressure, it was found that graphene could be grown on that surface. The surface symmetry of the Cu substrate has a strong influence on the rotational alignment of the graphene grains as they nucleate on each surface. For Cu(111), single-domain graphene growth can be achieved for ethylene pressures of 5 mTorr or less. For both Cu(100) and Cu(110), a minimum of two graphene domains is always observed.