Height-controlled InAs quantum dots by using a thin InGaAs layer

The structural and optical properties of height-controlled InAs quantum dots (QDs) have been investigated by transmission electron microscopy (TEM) and photoluminescence (PL). By depositing 1.4 nm ${\mathrm{In}}_{\text{0.15}}{\mathrm{Ga}}_{\text{0.85}}\mathrm{As}$ and a 1 monolayer (ML) InAs layer with different periods on 3 ML InAs QDs, the height of InAs QDs was systematically controlled with similar lateral size. In TEM images, the indication of dislocations due to the large strain, which can be easily seen in large QDs, is not observed even for the QD sample with the highest aspect ratio (height/width). The PL peak position is shifted toward the longer wavelength with an increase in the aspect ratio of QDs. As the aspect ratio is increased, the full width at half maximum in PL measured at 10 K is decreased from 71 to 34 meV indicating that the inhomogeneous broadening caused by the fluctuation in QD size, especially the height, is significantly reduced.