One- and zero-dimensional semiconductor structures attract significant research interest due to their unique electronic and optical properties, based on quantum confinement of the electron and hole motion. One of the major goals of our group is the development and optimization of zero-dimensional structures, known as quantum dots (QDs), which should contribute to the development of new optoelectronic devices with significantly improved performance.

The mostly used method for the growth of quantum dot structures is based on self-assembled Stranski-Krastanov growth mode by molecular beam epitaxy (MBE) or metalorganic chemical vapor deposition (MOCVD), which can be combined with pre-patterning of the substrate by electron beam lithography, allowing control of the density and dimensions of the structures.

Our current research activities are focused on the investigation of the influence of the MBE process parameters on the formation and growth of quantum dot structures, based on InGaAs/GaAs heterostructures by Varian Gen II MBE system (Fig. 1). The density and morphology of the QDs are assessed using scanning probe microscope SPM "CP II" or atomic force microscope AFM "Nanoscope III" (Fig. 2). Their optical properties are characterized ex-situ by photoluminescence (PL) and transmission spectroscopy as a function of the QD density and morphology, controlled by the MBE parameters (Figs. 3 - 6).