A novel imaging of surface adatom migration permitted the probing of impurity atoms, buried in a semiconductor, by using scanning tunneling microscopy. Atoms of Ga were adsorbed onto a chemically inactive H-terminated Si(100) surface, and thermal Ga-atomic motion was observed directly near to 100K. By exploiting the fact that the scanning tunnelling microscopic image revealed the thermodynamic distribution function of atomic trajectories, high-sensitivity detection of a positional variation in the surface potential was possible. The position of sub-surface P dopant was thereby deduced.

Direct Imaging of Thermodynamic Process in Atom Migration by Using Scanning Tunneling Microscopy. Y.Suwa, T.Hitosugi, S.Matsuura, S.Heike, S.Watanabe, T.Onogi, T.Hashizume: Japanese Journal of Applied Physics - 1, 2002, 41[5A], 3085-91