Structural instability of Si(1 1 1)-(7 × 7) induced by low-energy electron irradiation

We study structural changes on the Si(1 1 1)-(7 × 7) surface under low-energy electron irradiation with primary energies ranging from 15 to 30 eV. The irradiation induces bond breaking of adatoms of the reconstructed structure, leading to the formation of vacancies at the surface sites. The rate of vacancy formation is proportional to the electron intensity, and the cross section of vacancy formation decreases with increasing primary energy of incident electrons. Possible role of surface plasmon excitation has been discussed for the mechanism of electron-induced bond-breaking processes.