Carrier transfer among InAs/GaAs self-organized multi-coupled quantum dots was studied using time-resolved photoluminescence. In the multi-coupled quantum dots, since quantum dots couple with the other dots laterally, the photoexcited carriers tunnel into the relatively larger quantum dots which have lower energy levels. The photoluminescence decay time of multi-coupled quantum dots strongly depends on the energy in contrast with conventional quantum dots. The energy dependence can be explained with a cascade-like tunneling model assuming a tunneling time between quantum dots of 1300 ps.
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