STM image of a HOPG surface

HOPG crystals are widely used as substrates in STM (Scanning Tunneling Microscopy). The most distinguishing features of HOPG which enable this application are a very smooth surface and electro conductivity.

HOPG has a layered structure which makes sample preparation very simple. By pressing a double-stick tape to a HOPG piece and peeling it off, one gets a fresh conductive surface which is very smooth. This surface can be examined in STM or serve as a substrate for other materials under investigation.

HOPG itself is an interesting object for STM investigations. One can measure the surface roughness, microscopic surface features, arrangement of the carbon atoms on the HOPG surface, etc. Besides, HOPG images at the atomic level can be used for calibrating STM for high-resolution imaging.

Standard size of HOPG substrates amounts to 10 mm x 10 mm (or sometimes 12 mm x 12 mm). Usual value of mosaic spread for this application is 0.8 degrees. Other sizes and grades can be available on request.