Ultranarrow electroluminescence spectrum from the ground state of an ensemble of self-organized quantum dots

Data are presented on the electroluminescence from an ensemble of self-organized quantum dots excited at low current densities. The ensemble contains ∼105 dots, which produce a ground state spectral emission with a 14 K linewidth of ∼1 meV at low current density (∼5×10−2 A/cm2). While the spectra show clearly discrete energy levels, we suggest that obtaining a single ground state emission from the ensemble may be due to interdot electronic coupling. Spectral broadening decreases for decreasing current density due to electronic state filling, even for the lowest current densities studied.