Carrier dynamics in stacked InP/GaInP quantum dots

We measured time and spectrally reserved, resonantly and nonresonantly excited photoluminescence of self assembled vertically aligned InP/(GaIn)P quantum dots on GaAs substrates with various spacer thicknesses (2, 4, 8, and 16 nm) between the dot layers. The different interdot coupling in the various structures leads to considerable differences in the electron relaxation process. Carriers tunnel in the vertically aligned dot stacks to the lowest energy state when the spacer thickness is small, resulting in a pronounced red shift and slowing down of the photoluminescence decay. We present simple models to explain the results of our measurements.