Possibility of subsurface investigations by scanning tunnelling microscope

Scanning tunnelling microscope (STM) is a highly local probe of topology. It is also sensitive, however, to the three-dimensional electronic structure of the materials. We discuss how these features may be combined to allow the STM to be used for subsurface investigations. In particular, we discuss in detail the STM observations of quantum size effects (QSE). Supplementary techniques concerned with the Schottky barrier, connectivity and crystal orientation mapping are also discussed briefly.