AFM of hBN surface Dry Transfer and Characterization of Graphene Nanoribbons Dry Transfer Process Acknowledgments Background Bryan Manuele 1 , Juan Pablo Llinas 2 , Shuang Wu 2 , Kyunghoon Lee 2 , Jeongmin Hong, Jeffrey Bokor 2 1. Foothill Community College, 2. University of California, Berkeley The goal of the dry transfer process is to transfer a hexagonal Boron Nitride flakes onto any arbitrary substrate z 1. Prepare a Dry Transfer Stamp (PPC on PMDA on Glass) 2. Line up the dry transfer stamp with the target material, and anneal the surface till the material is securely on the stamp 3. Line up the dry transfer stamp with the target substrate, and anneal the surface till the material is securely deposited onto the substrate Special Thanks to: Prof. Jeff Bokor, Juan Pablo Llinas, Dr. Shuang Wu, Dr. Kyunghoon Lee, Dr. Jeongmin Hong. Graphene Nanoribbon Platform Atomic Force Microscopy Hexagonal Boron- Nitride Future Research Hexagonal Boron Nitride (hBN) is a suitable insulating substrate to characterize Graphene nanoribbons on due to its atomic smoothness (root mean square roughness of only 1.5 Å). 2um 100nm The lattice structure of hBN also matches that of graphene, and has a lattice constant difference of only 1.8% Graphene on h-BN lattice AFM of two adjacent h-BN flakes Summary Scanning Tunnel Microscopy (STM) of 13A wide Graphene Nanoribbons before transfer 1 We develop a transfer process to deposit hexagonal boron nitride flakes onto any arbitrary substrate, and characterized graphene nanoribbons by preforming atomic force microscopy on a GNR/hBN heterostructure. Graphene Nanoribbons (GNRs) with atomically precise <2 nm widths have potential applications in ultra-scaled transistor devices due to their semiconducting properties, but have yet to be characterized after transfer. 13A Graphene Nanoribbons before transfer Imaged using Atomic Force Microscopy GNRs are challenging to image after transfer because of their one Angstrom height profile. Roughness in the substrate underneath can cause the GNRs to appear undetectable. Atomic Force Microscopy of silicon Dioxide References 13A GNR 10Å Graphene Nanoribbon Transistor devices imaged with AFM AFM of Graphene Nanoribbons on h-BN Hexagonal Boron Nitride and Sapphire are both atomically smooth and transparent. We chose to image the GNRs on a hBN / sapphire Heterostructure, because doing so allows us to take AFM and optical measurements of the GNRs, Graphene Nanoribbon Field Effect Transistor that exhibits switching behaviour 2 1. Yen -Chia Chen, et al., ACS Nano 7, 6123 (2013) 2. Juan Pablo Llinas, et al., Short Channel Field Effect Transistors with 9 Atom an 13-Atom wide Graphene Nanoribbons 3. Duoming Wang, et al., PRL 116, 126101 (2016) 4. Abhisek Gupta, et al., Nanoscale 4, 6562-6567 (2014) 3nm 0nm Transferring h-BN onto Sapphire 3nm An atomically sharp tip on a cantilever taps along the surface of a substrate, resulting in a 2D plot of the height of the substrate. AFM image of Tungsten 150nm 15nm 0nm AFM Phase Image of Graphene Nanoribbons 10 ° 0 ° AFM Amplitude Image of Graphene Nanoribbons 5nm 0nm Section graph of SiO 2 substrate Section graph of hBN / sapphire heterostructure Optical image of the GNRs on the hBN / Sapphire heterostructure By depositing the GNRs onto an hBN / Sapphire heterostructure, we were able to image the GNRs using Atomic Force Microscopy. Our results show that the GNRs transfer cleanly when deposited onto an arbitrary substrate. Atomic Force Microscopy Schematic Atomic Force Microscope Graphic of Graphene Nanoribbons on a hBN / sapphire heterostructure 500 um 15nm 7nm 0 nm Thermally Induced Rotation In Graphene 3 Further research can be conducted in characterizing graphene nanoribbons. In the future, we plan to characterize them by measuring photoluminescence, and by observing thermally induced alignment in the GNRs. Photoluminescence of GNRs of varying widths 1um 1um 400nm 20x 200nm Support Information This work was funded by National Science Foundation Award ECCS- 1461157 & ECCS-0939514