Charging of embedded InAs self-assembled quantum dots by space-charge techniques

We present the results of both electrical and optical investigations of the charging of InAs self-assembled quantum dots embedded in a space-charge structure. Admittance spectroscopy was employed to study the electronic structures in quantum dots and their electron escape mechanisms. We resolved clear conductance features of different quantum-dot shells, enabling the study of electrons that escaped separately from different shells. Electron-filling modulation reflectance was used to investigate the interband transition influenced by the charging effects. Both the strengths and the energies of the interband transitions were modified in accordance with the electron occupation due to Pauli-blocking and the Coulomb-charging effects. The information acquired from these experimental observations is valuable for feasible device applications.