Chen Pingping

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

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 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.

Broadening of Photoluminescence by Nonhomogeneous Size Distribution of Self-Assembled InAs Quantum Dots

The photoluminescence spectrum (PL) of InAs quantum dots (QDs) at 80 K is studied by comparison between the theoretical calculation and experimental measurement. The Gaussian line shape is used to approximate the size distribution of QDs. Its mean volume and the standard size deviation are well correlated with the peak and full width at half maximum (FWHM) of the PL spectrum. The experimental PL spectrum is well reproduced by the theoretical model based on the effect mass approximation including the size distribution without any adjustable parameters. Compared with the standard size deviation value σs = 9 × 10-2 determined by atomic force microscopic method a small value σs = 7 × 10-2 is obtained by the best fitting process from the measured and calculated PL spectra.