Engineering of quantum dot structures for light emission in thespectral windows of photonic interest

In this paper we review how by a careful design of light-emitting quantum dot (QD) nanostructures grown on GaAs substrates it is possible to cover the 0.98-1.04 µm and 1.3-1.6 µm windows of photonic interest. To match the former window, AlGaAs confining layers and InGaAs QD structures have been successfully used to increase confinement energies and QD material energy gap; on the other hand, by means of QD strain engineering, that yields two degrees-of-freedom to tune two parameters of structures, the emission of metamorphic InAs/InGaAs QD structures is redshifted and room temperature operation is obtained up to 1.44 µm. The degrees-of-freedom are the composition of confining layers and the thickness of the lower one; they are used to control the band discontinuities and the energy gap of the QD material. To compensate for the decrease in band discontinuities, that is necessary for redshifting the emission of InAs/InGaAs QDs and that results in low luminescence eciency at room temperature, we propose the combined approach of QD strain engineering and barrier enhancing. This allows for room temperature emission at 1.51 µm, an achievement of great interest to extend to 1.55 µm and beyond the operation of QD nanostructures grown on GaAs substrates.