BOND BREAKING OF ADATOMS ON SI SURFACES BY ELECTRONIC EXCITATION

To understand the mechanism of defect initiated atomic emissions induc ed by electronic excitation of semiconductors, a semiempirical approac h is used to study the nature of the relaxed excited states for an Si adatom on the Si(lll) surface. We found an antibonding excited state e mbedded on the continuum and intermediate excited states, of which the relaxed states show bond weakening. Our results suggest that a series of excitation-relaxation processes can finally lead to the emission o f weakly bonded atoms associated with defects on the semiconductor sur face.