STM image with atomic resolution of a graphene flake on a SiO2 substrate.

ROM 2012-5
Author: Yuanbo Zhang 1),; Michael F. Crommie 1,2),
Institute: 1) Department of Physics, University of California at Berkeley, Berkeley, California, USA 2) Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California, USA
Publication: Nature Physics 4, 627 - 630 (2008)
Instrument: LT STM

STM measurements were carried out in an Omicron LT-STM at low temperature (T = 4.8 K) and in a UHV environment with base pressure < 10-11 mbar. STM measurements were conducted with chemically etched metal STM tips made of tungsten or platinum/iridium alloy. Corrugations having lateral dimension of a few nanometers and vertical dimension of ~ 1.5 Å (rms value over a 60 × 60 nm2 area) are observed, likely due to roughness in the underlying SiO2 surface and/or intrinsic ripples of the graphene sheet.