Design and realization of low density InAs quantum dots on AlGaInAs lattice matched to InP(0 0 1)

We present detailed growth studies of InAs nanostructures grown on Al _xGa_yIn_(1-x-y)As lattice matched to an InP(0 0 1) substrate using molecular beam epitaxy. Highly elongated quantum dash like structures are typically favoured in this material system, due to very anisotropic migration lengths along the [1 -1 0] and [1 1 0] directions. In order to increase the short migration length along the [1 1 0]-direction we used ultra low growth rates down to 3×10^-3 monolayers per second. We show that this offers the possibility to form InAs quantum dots with a low surface density, in contrast to the most commonly formed quantum dash structures. To tailor the emission wavelength of the quantum dots, three methods were studied: (i) the variation of the bandgap of the surrounding material by adjusting the aluminium to gallium ratio, (ii) the variation of the bandgap of the quantum dot material by incorporating antimony and (iii) the variation of the height of the quantum dots by closely stacking two layers of quantum dots upon each other.