MICROSCOPIC EXCITATION SPECTROSCOPY FOR ZERO-DIMENSIONAL QUANTIZED STATES OF INDIVIDUAL INXGA1-XAS ALYGA1-YAS QUANTUM DOTS/

We investigate the optical transition of a small number of In0.4Ga0.6A s quantum dots fabricated by self-organized growth on a (311)B GaAs su bstrate by microscopic photoluminescence and excitation spectroscopy. The luminescence shows very sharp peaks. By tuning the detection at th ese peaks, discrete and narrow absorption lines are observed in the ex citation spectrum, which are assigned to zero-dimensional (OD) quantiz ed levels. Resonant excitation experiments clarify their discrete natu re, which is a manifestation of zero dimensionality. This discreteness allows us to detect a single dot selectively, even when a number of d ots are illuminated. Analysis of the homogeneous broadening of these O D quantized levels indicates that there is no threshold behavior at LO -phonon energy.