Graphene Moiré Pattern Ultra-High Resolution Atomic Force Microscopy

B. Kim
Park Systems,
United States

Keywords: AFM, high resolution

Summary:

The ultra-high resolution of AFM was demonstrated in a Graphene/hexagonal Boron Nitride (hBN) sample evaluation conducted by AFM. The sample consisted of hBN substrate overlaid with a Graphene layer and was scanned under ambient air. The purpose of the evaluation was to assess the AFM ability to characterize the topography of the moiré pattern that was created when one layer was set on top of the other and offset by rotation. Using non-contact AFM mode and a standard AFM probe tip, the AFM was able to successfully image the moiré pattern super lattice constant of the sample in scans as large as 500 x 500 nm. In the higher magnification image taken at a scan size of 60 x 60 nm provides the clear evidence that not only are the super lattice constants of the moiré pattern about 15 nm [1] in width, but that the spacing between each striation on the moiré pattern is roughly 4-5 nm in length. Observations of such striations in Graphene/hBN systems have been previously reported [2]. This latter distance is in line with the expected tip radius curvature values for the AFM tip used to acquire all four sets of data. [1] A. Zandiatashbar, B. Kim, Y. Yoo, and K. Lee, Microscopy Today 23(06):26-31 (2015) [2] P. Gallagher, M. Lee, F. Amet et.al., Nature Comm. 7 10745 (2016)