PhD Defense by Gabija Kirsanské

Electrical control of excitons in semiconductor nanostructures: from quantum dots in
photonic-crystal devices to the exciton Mott transition in coupled quantum wells.

In this talk, I will present the main results of my PhD thesis entitled „Electrical control of excitons in semiconductor nanostructures: from quantum dots in photonic-crystal devices to the exciton Mott transition in coupled quantum wells“.

First, I will discuss the fabrication process of photonic-crystal structures on electrically gated GaAs samples with embedded self-assembled quantum dots. This process is employed to investigate light localization in short photonic-crystal waveguides with a dispersion relation facilitating a slow-light effect.

The second part of the talk concerns the exciton Mott transition, which is a phase transition occurring in a population of interacting electrons and holes, in which insulating excitons are ionized to a metallic phase of free carriers. It is still debated in the literature whether the Mott transition in quantum wells occurs gradually or abruptly as a function of the governing parameters - exciton density and temperature. In this work, the Mott transition is studied with indirect excitons with electrically extended radiative lifetime and is found to occur gradually as a function of exciton density and temperature.