Inhibited carrier transfer in ensembles of isolated quantum dots

We report significant differences in the temperature-dependent and time-res olved photoluminescence (PL) from low and high surface density InxGa1-xAs/G aAs quantum dots (QDs). QD's in high densities are found to exhibit an Arrh enius dependence of the PL intensity, while low-density (isolated) QD's dis play more complex temperature-dependent behavior. The PL temperature depend ence of high density QD samples is attributed to carrier thermal emission a nd recapture into neighboring QD's. Conversely, in low density QD samples, thermal transfer of carriers between neighboring QD's plays no significant role in the PL temperature dependence. The efficiency of carrier transfer i nto isolated dots is found to be limited by the rate of carrier transport i n the InxGa1-xAs wetting layer. These interpretations are consistent with t ime-resolved PL measurements of carrier transfer times in low and high dens ity QD's. [S0163-1829(99)04748-7].