Electronic structure of self-assembled InAs quantum dots

Electroluminescence (EL) is always related to carrier transport (i.e. current flow) into an active region. We used EL and transport measurements to study in detail the electronic structure in InAs quantum dots (QDs) embedded in the intrinsic GaAs region of a double hetero p–i–n diode. According to the position of the dot layer with respect to the n- and p-doped regions we independently investigated the QD levels of electrons and holes. From the differential capacitance the Coulomb blockade energy for electrons in the QD ground state and the energy splitting between the ground and first excited state in the conduction band system was extracted. Additionally the energy separation of the electron ground state from the GaAs conduction band edge was determined by the same technique. The energetic distance between the hole ground and first excited state can be estimated from the electroluminescence signal as well as from the differential conductance.