STARK-EFFECT IN INDIVIDUAL LUMINESCENT CENTERS OBSERVED BY TUNNELING LUMINESCENCE

We have measured photon emission from individual luminescent states in GaInP/InP heterostructures, containing InP dots, using local injectio n from a scanning tunneling microscope tip. By changing the tip-sample bias we are able to see the Stark shift of the emission peaks, as wel l as the onset of impact ionization. We find that the exciton diffusio n length is about 1 mu m, while the minority carrier diffusion length is much less in our samples. Below the threshold for impact ionization the excitation is extremely local, limiting the excitation to one or a few quantum dots. (C) 1996 American Institute of Physics.