Growth-temperature dependence of wetting layer formation in high density InGaAs/GaAs quantum dot structures grown by droplet epitaxy

We present a study of the growth-temperature-dependent wetting layer formation in self-assembled InGaAs/GaAs quantum dot structures formed by droplet epitaxy at elevated growth temperatures up to 500 \'01C. The energies of electron heavy-hole and light-hole transitions of the InGaAs wetting layer is investigated by contactless electroreflectance spectroscopy. A clear indication of a strong growth-temperature influence on the wetting layer morphology is observed. At the lowest growth temperature no wetting layer could be detected at all. The influence of the substrate temperature on structural and optical properties of the dots is also discussed.