| AVS 62nd International Symposium & Exhibition | |
| 2D Materials Focus Topic | Monday Sessions |
| Session 2D+EM+NS+PS+SP+SS+TF-MoM |
| Session: | 2D Materials: Growth and Fabrication |
| Presenter: | Alexander Yulaev, National Institute of Standards and Technology (NIST), University of Maryland (UMD) |
| Authors: | A. Yulaev, National Institute of Standards and Technology (NIST), University of Maryland (UMD) G. Cheng, National Institute of Standards and Technology (NIST) A. Hight Walker, National Institute of Standards and Technology (NIST) M. Leite, University of Maryland (UMD) A. Kolmakov, NIST |
| Correspondent: | Click to Email |
Clean suspended graphene is used as supporting media in TEM, filtering membranes, and as electron transparent windows in ambient pressure electron spectroscopy and microscopy. CVD grown graphene is the most popular material for these applications due to its large-scale and high yield production. Multiple approaches such as sacrificial layer based methods [1] and direct transfer method on perforated carbon mesh by IPA droplet [2] have been implemented to transport graphene from copper or nickel foil onto a target substrate. However, the cleanness of the suspended graphene remains to be an issue, and controversial results on lateral size of atomically clean graphene domains have been reported [2-5]. We conduct the comparative analysis of the most widely-used CVD graphene transfer and cleaning protocols. In particular, using extreme surface sensitivity of low energy SEM, we compare the standard PMMA based approach with direct graphene transfer method. We also propose alternative graphene transfer protocol which is based on employment of polycyclic aromatic hydrocarbon (PAH) as a sacrificial layer. The advantage of PAH method over others consists in facile sublimation of sacrificial layer upon heating PAH material within moderate temperature range of 100-150 oC. All three methods of graphene transfer were compared under the same conditions followed by similar graphene cleaning procedures by platinum catalysis [4] and activated carbon adsorption [5]. Both SEM and TEM study revealed the superiority of PAH method to achieve cleaner suspended CVD graphene. We envision that novel approach of graphene transfer can be employed under conditions when exposure of the sample to moisture is prohibited such as in battery research.
[1] “Transfer of CVD-Grown Monolayer Graphene onto Arbitrary Substrates”, Ji Won Suk et al., ACS Nano, 2011, 5 (9), pp. 6916.
[2] “A direct transfer of layer-area graphene”, William Regan et al., Appl. Phys. Lett., 2010, 96, 113102.
[3] “Low-energy electron holographic imaging of gold nanorods supported by ultraclean graphene”, Jean-Nicolas Longchamp et al., Ultramicroscopy 145 (2014) 80.
[4] “Ultraclean freestanding graphene by platinum-metal catalysis”, Jean-Nicolas Longchamp et al., J. Vac. Sci. Technol. B 31, 020605 (2013).
[5] “Dry-cleaning of graphene”, Gerardo Algara-Siller et al., Applied Physics Letters 104, 153115 (2014).