1.3 $\mu $m room temperature emitting multiple-stacked InAs/GaAs(001)
quantum dots (QDs) are grown by molecular beam epitaxy (MBE) and
investigated by photoluminescence (PL), polarized photoluminescence (PPL),
photoluminescence excitation (PLE), time resolved photoluminescence (TRPL)
and atomic force microscopy AFM. The PL measurement shows that two distinct
sets of QDs coexist in the sample. The AFM image of the tenth QDs layer not
only confirms the bimodal size distribution of the QDs but also shows that
the large QDs are elongated along the [1-10] direction. The former
structural information has been verified by PPL. Through the excitation
density dependent PL and the detection energy dependent PLE we have
evidenced two kinds of QDs within the small size dots population: isolated
QDs and laterally coupled QDs with vertically coupled large size QDs. The
large size dot population is found to possess a long PL decay time
confirming that they are electronically coupled. In the meanwhile the PL
decay time of the small QDs is found to be similar to that of single layer
QDs. These results would help improve understanding some fundamental
properties of an interesting structure for optoelectronic applications.