The effect of high-In content capping layers on low-density bimodal-sized InAs quantum dots

[EN] The structural and morphological features of bimodal-sized InAs/(In) GaAs quantum dots with density in the low 10(9) cm(-2) range were analyzed with transmission electron microscopy and atomic force microscopy and were related to their optical properties, investigated with photoluminescence and time-resolved photoluminescence. We show that only the family of small quantum dots (QDs) is able to emit narrow photoluminescence peaks characteristic of single-QD spectra; while the behavior of large QDs is attributed to large strain fields that may induce defects affecting their optical properties, decreasing the optical intensity and broadening the homogeneous linewidth. Then, by using a rat…