Observation of tilt boundaries in graphite by scanning tunneling microscopy and associated multiple tip effects

Abstract

Tilt boundaries have been observed on the (0001) surface of graphite by scanning tunneling microscopy (STM). Rotation angles about the c axis of 6.5°, 8°, and 19° were found, indicating no preferential orientation of grains in the basal plane of graphite. The grain boundary region between crystallites appears disordered with a width varying between 10 and 100 Å. Moiré patterns are observed near grain boundaries when multiple tips scanning over different grains contribute to the image simultaneously. Such images support the theory that multiple isolated tips, occasionally hundreds of angstroms apart, can contribute to STM images.