Simultaneous observation of scanning tunneling microscopy and reflection electron microscopy image of the Si(111)7×7 surface

Atomic structures of scanning tunneling microscopy (STM) tips were characterized by reflection electron microscopy (REM). The Si(111)7×7 surface was observed simultaneously by REM and STM in an ultrahigh vacuum electron microscope. In high-resolution REM images of the specular beam reflection, a tungsten tip apex was observed with its mirror image. The distance between the true and the mirror images was used to estimate the tip-surface distance. As the tip scanned over the Si(111) surface in STM experiments, the tip apex was scraped to give a plateau of a (110) atomic surface. An atomic-resolution STM image of the Si(111)7×7 surface was obtained when the STM tip apex had a single atom on the (110) terrace.