National Natural Science Foundation of China (Grant No. 61375107, 61175103), Bureau of International Cooperation, Chinese Academy of Sciences (Grant No. 17321KYSB20130006), Project supported by Science and Technology Development Project of Jilin Province, China (Grant No. 20160520098JH), Key Project of High Education and Scientific Research of Jinlin Province of China (Grant No. JGJX2015C55), the12th Five-Year Plan Project of Education and Sciences of Jinlin Province of China (Grant No. GH150554), and the CAS FEA International Partnership Program for Creative Research Teams.
Rapid progress in graphene engineering has called for a simple and effective method to determine the lattice orientation on graphene before tailoring graphene to the desired edge structures and shapes. In this work, a wavelet transform-based frequency identification method is developed to distinguish the lattice orientation of graphene. The lattice orientation is determined through the different distribution of the frequency power spectrum just from a single scan line. This method is proven both theoretically and experimentally to be useful and controllable. The results at the atomic scale show that the frequencies vary with the lattice orientation of graphene. Thus, an adjusted angle to the desired lattice orientation (zigzag or armchair) can easily be calculated based on the frequency obtained from the single scan line. Ultimately, these results will play a critical role in wafer-size graphene engineering and in the manufacturing of graphene-based nanodevices.