Full Length Article Direct dry transfer of CVD graphene to an optical substrate by in situ photo-polymerization Felipe Kessler a,b , Pablo A.R. Muñoz a , Ciaran Phelan a , Eric C. Romani c , Dunieskys R.G. Larrudé a , Fernando L. Freire Júnior c , Eunézio A. Thoroh de Souza a , Christiano J.S. de Matos a , Guilhermino J.M. Fechine a,⇑ a MackGraphe – Graphene and Nanomaterials Research Center, Mackenzie Presbyterian University, Brazil b Laboratory of Applied and Technological Physical Chemistry, Federal University of Rio Grande, Brazil c Department of Physics, Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Brazil article info Article history: Received 17 September 2017 Revised 9 January 2018 Accepted 15 January 2018 Keywords: Graphene transfer In situ polymerization Photocurable resin Third-harmonic generation abstract Here, we report on a method that allows graphene produced by chemical vapor deposition (CVD) to be directly transferred to an optically transparent photo resin, by in situ photo-polymerization of the latter, with high efficiency and low contamination. Two photocurable resins, A and B, with different viscosities but essentially the same chemical structure, were used. Raman spectroscopy and surface energy results show that large continuous areas of graphene were transferred with minimal defects to the lower viscos- ity resin (B), due to the better contact between the resin and graphene. As a proof-of-principle optical experiment, graphene on the polymeric substrate was subjected to high-intensity femtosecond infrared pulses and third-harmonic generation was observed with no noticeable degradation of the sample. A sheet third-order susceptibility v ð3Þ ¼ 0:71  10 28 m 3 V 2 was obtained, matching that of graphene on a glass substrate. These results indicate the suitability of the proposed transfer method, and of the photo resin, for the production of nonlinear photonic components and devices. Ó 2018 Elsevier B.V. All rights reserved. 1. Introduction Several methods for 2D material transfer have been proposed in recent years [1–11]. However, most of these do not yield large transferred areas with simplicity and low cost. Additionally, the quality of the transfer, defined as the absence of cracks and con- tamination on the graphene sheets, varies with the kind of applica- tion and transfer method. Full advantage of graphene’s excellent properties will only be obtained for the development of practical devices if researchers are able to develop transfer methods that are direct, fast and clean, which means they should preferably not contain steps requiring the contact of graphene with chemicals or intermediate substrates that can cause defects or spurious dop- ing in graphene. Chemical vapor deposition (CVD) is currently the best process to produce large areas of 2D materials, such as graphene, boron nitride (BN), molybdenum disulphide (MoS 2 ), among others. For most applications, the 2D material must be used on an appropriate substrate, e.g., dielectric/semiconducting for electronic or opto- electronic applications; transparent for photonic applications. However, the process of transferring the 2D crystal from its origi- nal substrate to the desired substrate usually contaminates the sample, affecting the performance of devices. In the most common graphene transfer methodology, known as the ‘‘wet transfer” method [12], multiple steps lead to samples with questionable quality due to the presence of cracks and ripples, as well as poly- mer and metal residues. In addition, the contact between graphene and the substrate is weak after the transfer, requiring a heat treat- ment (annealing) to increase the grip [12]. For photonic applica- tions, contamination with the polymer used for the transfer and traces of graphene’s original substrate lead to light scattering and absorption, increasing the device’s insertion loss. In addition, devices based on nonlinear optical effects, such as saturable absor- bers [13] and frequency converters [14], require high optical inten- sities, in which case contamination increases the failure rate due to absorption-induced damage. Indeed, graphene has been shown to present a high third-order nonlinearity, from which frequency con- version can be obtained via four-wave mixing [15] and third- harmonic generation [16,17], with important perspective photonic applications. Her et al. [6] and Liang et al. [18] have conducted studies to reduce the amount of polymer residue after the transfer in order https://doi.org/10.1016/j.apsusc.2018.01.142 0169-4332/Ó 2018 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail address: guilherminojmf@mackenzie.br (G.J.M. Fechine). Applied Surface Science 440 (2018) 55–60 Contents lists available at ScienceDirect Applied Surface Science journal homepage: www.elsevier.com/locate/apsusc