posted on 2020-05-27, 15:35authored byJun Hee Choi, Dong Hoon Shin, Heena Inani, Min Hee Kwon, Kimmo Mustonen, Clemens Mangler, Min Park, Hyunjeong Jeong, Dong Su Lee, Jani Kotakoski, Sang Wook Lee
Dynamic
surface modification of suspended graphene at high temperatures was
directly observed with in situ scanning transmission electron microscopy
(STEM) measurements. The suspended graphene devices were prepared
on a SiN membrane substrate with a hole so that STEM observations
could be conducted during Joule heating. Current–voltage characteristics
of suspended graphene devices inside the STEM chamber were measured
while monitoring and controlling the temperature of graphene by estimating
the electrical power of 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. The temperature
of the suspended graphene sample was estimated to reach up to 2000
K during the experiment, making graphene an efficient high-temperature
micrometer-sized electron-transparent hot plate for future experiments
in microscopes.