  Carrier dynamics of submonolayer (SML) InGaAs/GaAs quantum dots (QDs) were
studied by micro-photoluminecence (MPL), selectively excited photoluminescence
(SEPL), and time-resolved photoluminescence (TRPL). MPL and SEPL show the
coexistence of localized and delocalized states, and different local phonon
modes. TRPL reveal shorter recombination lifetimes and longer capture times for
the QDs with higher emission energy. This suggests that the smallest SML QDs
are formed by perfectly vertically correlated 2D InAs islands, having the
highest In content and the lowest emission energy, while a slight deviation
from the perfectly vertical correlation produces larger QDs with lower In
content and higher emission energy.
