  We report on the use of an aperture in an aluminum oxide layer to restrict
current injection into a single self-assembled InAs quantum dot, from an
ensemble of such dots within a large mesa. The insulating aperture is formed
through the wet-oxidation of a layer of AlAs. Under photoluminescence we
observe that only one quantum dot in the ensemble exhibits a Stark shift, and
that the same single dot is visible under electroluminescence. Autocorrelation
measurements performed on the electroluminescence confirm that we are observing
emission from a single quantum dot.
