Graphene: Mechanical Properties, Transfer, Manupulation


Tunable Excitons in Biased Bilayer Graphene

Constanze Metzger, Sebastian Rmi, Mengkun Liu, Silvia V. Kusminskiy, Antonio H. Castro Neto, Anna K. Swan and Bennett B. Goldberg


Nano Lett., 2010, 10 (1), pp 6–10

Measurements on graphene exfoliated over a substrate prepatterned with shallow depressions demonstrate that graphene does not remain free-standing but instead adheres to the substrate despite the induced biaxial strain. The strain is homogeneous over the depression bottom as determined by Raman measurements. We find higher Raman shifts and Grneisen parameters of the phonons underlying the G and 2D bands under biaxial strain than previously reported. Interference modeling is used to determine the vertical position of the graphene and to calculate the optimum dielectric substrate stack for maximum Raman signal.

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Transfer Printing of Graphene Using Gold Film

Li Song, Lijie Ci, Wei Gao, and Pulickel M. Ajayan

ACS Nano,2009

Highly oriented pyrolytic graphite (HOPG) is one of the best sources for high crystallinity graphene layers. Graphene, a popular material of recent times, is a single layer of graphite and a perfect 2D crystalline material with very high electron mobility and other interesting properties. Graphene has become an ideal object for both fundamental studies and future electronic applications. During last several years, there have been many efforts for exfoliating HOPG into multiple layers and even to obtain monolayer graphene, such as via chemical exfoliation, mechanical cleavage, and electrostatic force based separation. By improving the micromechanical cleavage technique, Novoselov et al. fixed graphite onto a substrate with glue and then used a tape to repeatedly peel off graphene.They found that individual single- and few-layer graphene could be successfully isolated from graphite by the repeated peeling-off process. Most recently, Liang et al. used a stamp with thousands of pillars to choose cut graphene islands from graphite. By applying voltage between graphite and the substrate, they found that the graphene islands could be exfoliated onto a silicon wafer by electrostatic force. However, there are still issues to be resolved in order to easily manipulate and transfer graphene on a large scale.

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Transferring and Identification of Single- and Few-Layer Graphene on Arbitrary Substrates

Alfonso Reina, Hyungbin Son, Liying Jiao, Ben Fan, Mildred S. Dresselhaus, ZhongFan Liu, and Jing Kong

J. Phys. Chem. C, 2008, 112 (46), pp 17741–17744

The transferring and identification of single- and few- layer graphene sheets from SiO2/Si substrates to other types of substrates is presented. Features across large areas (?cm2) having single and few-layer graphene flakes, obtained by the microcleaving of highly oriented pyrolytic graphite (HOPG), can be transferred reliably. This method enables the fast localization of graphene sheets on substrates on which optical microscopy does not allow direct and fast visualization of the thin graphene sheets. No major morphological deformations, corrugations, or defects are induced on the graphene films when transferred to the target surface. Moreover, the differentiation between single and bilayer graphene via the G? (?2700 cm-1) Raman peak is demonstrated on various substrates. This approach opens up possibilities for the fabrication of graphene devices on a substrate material other than SiO2/Si.

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Printed Graphene Circuits

Jian-Hao Chen, Masa Ishigami, Chaun Jang, Daniel R. Hines, Michael S. Fuhrer, and Ellen D. Williams

Advanced Materials 19, 3623 (2007)

Flexible and transparent electronic devices with extremely high mobilities are fabricated from a graphene sheet, a single atomic layer of graphite, by using the transfer printing method. Printed graphene circuits achieve field effect mobilities of up to 10000 cm2/Vs at room temperature. Our printing technique is scaleable and a more chemically-gentle process for fabricating high quality graphene, and nanoscale devices in general.

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