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OO4.07 - Large Area Single and Bilayer Graphene with Controlled Orientation for Each Layer 
April 22, 2014   9:45am - 10:00am

The creation and exploration of artificial graphene structures has recently become the focus of great interest. In particular, controlling the interlayer rotation (or twist) angles in multilayer graphene stacks allows one to modulate the overall band structure. However, producing such a structure remains difficult due to the random distribution of twist angles in as-grown samples. Here we report a novel way for creating large area graphene stacks with a pre-determined twist angle. We first grow single layer graphene whose orientation is aligned over a few cm length scale on copper foil using chemical vapor deposition (CVD) method. The overall and local angle alignment of this graphene sample is confirmed using low energy electron microscopy (LEED), dark-field transmission electron microscopy (DF-TEM) and selected area electron diffraction (SAED) techniques. Since the graphene is well aligned over a few centimeters, we can create large area graphene stacks with known twist angle by transferring these graphene layers while controlling the orientation of each layer during transfer. We confirm that the layers are coupled with the designed twist angle, by probing the resulting band structure using angle resolved photoemission spectroscopy (ARPES) and examining their interlayer optical resonance features using spatially resolved hyperspectral (DUV-Vis-NIR wavelengths) measurements. This new method is scalable, controllable, and uses commercially available copper foil, and thus paves the way to explore and exploit the novel properties of two-dimensional crystals in artificial stacks with controlled interlayer structures.

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Keynote Address
Panel Discussion - Different Approaches to Commercializing Materials Research
Business Challenges to Starting a Materials-Based Company
Fred Kavli Distinguished Lectureship in Nanoscience
Application of In-situ X-ray Absorption, Emission and Powder Diffraction Studies in Nanomaterials Research - From the Design of an In-situ Experiment to Data Analysis