Temperature-Dependent Optical Properties of InAs/GaAs Self-Assembled Quantum Dots: Spectroscopic Measurements and an Eight-Band Study

摘要

The temperature-dependent optical properties of InAs/GaAs self-assembled quantum dots are studied by spec-troscopic measurements along with the corresponding theoretical calculations. We observe the redshift of pho-toluminescence peak energy with increasing temperature and the thermally activated quenching of each state, which result from the efficient redistribution of carriers in quantum dots. Meanwhile, the electronic structures of the InAs/GaAs quantum dots are investigated by a detailed theoretical study in terms of an eight-band k-p model, taking strain effects into account. The calculated transition energies of the excitons are in reasonable agreement with the results of the photoluminescence spectra. According to the spatial distribution of carriers, it is found that the evolution of photogenerated excitons in quantum dots with temperature mainly relies on the electrons rather than the holes.%The temperature-dependent optical properties of InAs/GaAs self-assembled quantum dots are studied by spectroscopic measurements along with the corresponding theoretical calculations.We observe the redshift of photoluminescence peak energy with increasing temperature and the thermally activated quenching of each state,which result from the efficient redistribution of carriers in quantum dots.Meanwhile,the electronic structuresof the InAs/GaAs quantum dots are investigated by a detailed theoretical study in terms of an eight-band k·p model,taking strain effects into account.The calculated transition energies of the excitons are in reasonable agreement with the results of the photoluminescence spectra.According to the spatial distribution of carriers,it is found that the evolution of photogenerated excitons in quantum dots with temperature mainly relies on the electrons rather than the holes.Semiconductor quantum dots (QDs) as lowdimensional nanostructures have been receiving great attention for more than two decades due to their promising properties for optical devices such as laser diodes and infrared photodetectors.[1-3] It has been reported that the growth mode of InAs changes from 2D to 3D upon the deposition of less than two monolayers of InAs,so as to reduce the strain in a grown layer,since there is about a 7％ lattice mismatch in the InAs/GaAs system.[4] InAs/GaAs self-assembled QDs have been most widely studied and various quantum effects have been demonstrated.[5] To make QD-based devices work at room temperature,it is essential to investigate the temperature dependence of the optical properties of QDs.