Abstract

We observe a strong bias-dependence of the electroluminescence spectra of an ensemble of self-assembled InAs quantum dots (QDs) excited by tunnelling injection of carriers from the n- and p-doped GaAs layers of a p-i-n diode. We show that the dot emission evolves from a broad band above flat-band condition to a series of sharp emission lines below a characteristic bias voltage. Also, we present a study of the electroluminescence under resonant bias excitation of the dots and demonstrate up-conversion luminescence. © 2007 American Institute of Physics.