The state filling effect in p-doped InGaAs/GaAs quantum dots

The electron dynamics in modulation p-doped InGaAs/GaAs self-assembled quantum dots have been studied by time-integrated and time-resolved upconversion photoluminescence. A significant state filling effect is observed with exclusion of the phonon bottleneck effect. The rise time and decay time are found to vary with the excitation intensity for the ground state and excited states of the quantum dots. In the low intensity regime the rise time decreases with increasing excitation intensity because of the increased scattering between the photoexcited electrons and excess holes. By contrast, in the high excitation regime the rise time exhibits a slight decrease due to the state filling effect. A simplified rate equation model indicates that the modulation p-doped quantum dots exhibit an increasing saturation factor with increasing detection photon energy based on the theory of parabolic confinement of the quantum dots, which is consistent with the observed excitation dependence. (Some figures in this article are in colour only in the electronic version)