Carrier transfer effects and thermal activation behaviors in the photoluminescence of In(Ga)As self-assembled quantum dots

We report the temperature-dependent [photoluminescence] (PL) of InAs and In_xGa_1-xAs quantum-dot (QD) systems. Due to the effect of carrier transport in the wetting layer (WL), anomalous increases in the QD PL intensity at low temperatures are found. Several factors, such as dot density, confinement energy, transport limit, and intentional doping, are found to be important in the temperature dependent QD PL. In particular, an enhanced increasing PL is found in the n-type barrier-doped sample. This suggests that the scattering center, as well as the accumulated electrons in QDs, would significantly influence the carrier transport properties in the WL. We also develop a quantum-well-like coupled rate-equation approach to describe the temperature dependent QD PL intensity. The effect of carrier transport is introduced by considering a temperature-dependent carrier diffusion in the capture processes. This model gives satisfactory descriptions of both the increasing PL intensity at low temperatures and the thermal activation behavior at high temperatures.