  Electron injection from the tip of a scanning tunneling microscope into a
p-type GaAs(110) surface have been used to induce luminescence in the bulk.
Atomically-resolved photon maps revealed significant reduction of luminescence
intensity at surface states localized near Ga atoms. Quantitative analysis
based on the first principles calculation and a rate equation approach was
performed to describe overall energy dissipation processes of the incident
tunneling electrons. Our study shows that the recombination processes in the
bulk electronic states are suppressed by the fast electron scattering at the
surface, and the electrons dominantly undergo non-radiative recombination
through the surface states.
