Migration of subsurface self-interstitial atoms of the Ge(113) surface and the energy barrier

It has been pointed out very recently that in each (3 x 2) unit cell of the Ge(113) surface, similar to the Si(113) surface, there is a subsurface self-interstitial atom. In the present paper we have observed with scanning tunneling microscopy that such interstitial atoms of clean and well-annealed Ge(113) surfaces migrate frequently even at room temperature. The energy barrier of the migration has been determined to be 0.93 +/- 0.02 eV from the measured rate of the migration, if the migration is a simple thermally activated process and an attempt frequency of 10(13) Hz is used.