Transformation and Evaporation of Surface Adsorbents on a Graphene "Hot Plate".

: Dynamic surface modification of suspended graphene at high temperatures was directly observed with in situ scanning transmission electron microscopy (STEM) measurement. The suspended graphene devices were prepared on a SiN membrane with hole substrate so that STEM observation could be conducted during Joule heating. Current-voltage characteristics of suspended graphene devices inside of STEM chamber were measured while monitoring and controlling the temperature of graphene by estimating electrical power on the devices. During the in situ STEM observation at high temperatures, residual hydrocarbon adsorbents that had remained on graphene effectively evaporated creating large atomically clean graphene areas. At other places, dynamic changes in the shape, position and orientation of adsorbents could be directly observed. Temperature of the suspended graphene sample was estimated to reach up to 2000 K during the experiment, making it an efficient high-temperature µm-sized electron transparent hot plate for future experiments in the microscope.