Computational study of the effect of surface defects and steps on field-stimulated exoelectron emission from aluminum

Abstract

The electronic structures of a clean Al (001) surface, of a stepped Al (001) surface, and of an Al(001) surface with vacancies were investigated by the first-principles calculation to elucidate the emission mechanism of field-stimulated exoelectrons from Al tip surfaces. The results show that vacancies at the Al (001) surface slightly increase local density of states (LDOS) in the occupied states, and that monoatomic steps significantly increase LDOS at 0.36 eV above Fermi level in the unoccupied states. The LDOS peak position in the unoccupied states at the stepped surface is close to the trap level of field-stimulated exoelectrons measured in our previous experiments, and it is concluded that the monoatomic steps at Al surfaces can play a role of exoelectron traps.