Adatom diffusion on Ge(111) and the corresponding activation energy barrier

In this paper, surface diffusion of Ge adatoms on the In-stabilized moderate temperature phase of Ge(111) was studied with a room-temperature scanning tunneling microscope and it has been found that, in addition to diffusion of individual adatoms neighboring to some defects, the majority of the moving adatoms forms strings or closed loops consisting of segments lying along 〈110〉 directions. The mean lifetime of Ge adatoms on Ge(111) has been obtained, from which the activation energy barrier has been determined to be 0.83 ± 0.02 eV. This experimental result of this quantity is in excellent agreement with its theoretical value for clean Ge(111) surfaces, thus showing not only that the energy barrier obtained here is a characteristic of clean Ge(111) surfaces, but also that there is no complicated collective motion involved in surface diffusion of Ge adatoms.