Electronic coupling effects on the optical properties and carrier dynamics of InAs quantum dots

Vertically aligned InAs/GaAs quantum dot structures were investigated. They were grown by atomic layer molecular beam epitaxy, with 10 layers and wedged spacer thickness d varying between 7.7 and 12.5 nm at steps of 0.2 nm. The effects of electronic coupling on the fundamental transition energy and decay dynamics were studied by time-resolved and continuous-wave photoluminescence (PL). The energy of the PL peak position decreases with increasing d, while the corresponding lifetime increases with d. This is attributed to the interplay of the electronic delocalization along the column and the Coulomb interaction between electrons and holes. Furthermore, a bell-shaped behaviour of the PL lifetime as a function of emission energy was observed inside the inhomogeneously broadened PL band.