Effect of growth interruption on photoluminescence of self-assembled InAs/GaAs quantum dot heterostructures

The effects of growth interruption (GI) on self-assembled InAs/GaAs quantum dot (QD) heterostructures have been presented. Samples with different GI times were grown on GaAs substrate by metal-organic chemical vapour epitaxy. Photoreflectance and temperature dependent photoluminescence (PL) spectra from the samples were measured. It is found that increasing GI time during InAs QDs formation induces a larger dot size and a higher QD size uniformity. The carrier dynamics in QD system has been investigated in detail by analyzing the PL spectra. With increasing temperature, thermal redistribution effect among dots is evident for the sample with shorter GI time, leading to a quick red-shift of the PL peak energy and a reduction of the PL line width in mid-temperature range. On the other hand, for sample with longer time, such effect is weak and overcome by the electron-phonon scattering effect, which is consistent with the observed monotonically increasing linewidth of PL spectra with temperature.