Temperature dependence of photoluminescence spectra in InAs/GaAs quantum dot superlattices with large thicknesses

Abstract

In this report, we investigate the thermal relaxation of the photoluminescence (PL) in InAs/GaAs quantum dot superlattices with large thicknesses that have two to more than three times the critical thickness for spontaneous island formation. It is found that the linewidth first decreases and then increases with increasing temperature. In addition to thermionic emission, we suggest that carrier repopulation among quantum dots plays an important role in the PL quenching. The temperature dependence of PL peak energy following a Varshni relation was attributed to the dilation of lattice and electron-lattice interaction. The emission intensity quenches rapidly when the temperature rises to around 60 K, indicating the existence of defect-related centers in the vicinity of InAs/GaAs interfaces. In addition, we performed the measurement of the activation energy of PL quenching at different emission energy. We found that the loss mechanism of PL quenching based on the activation of electron-hole pairs from quantum dots to the adjacent barriers was difficult to explain the behavior in quantum dots with large thicknesses. In this case, we suggest that the PL quenching is dominated by the recombination through interface defects.