Observation of quantum dot levels produced by strain modulation of GaAs–AlGaAs quantum wells

We present the first observation of resolved quantum dot levels produced by strain modulation of a semiconductor. Excitons are confined in lateral potential wells of up to 60 meV, the largest yet reported for strain-induced quantum wire or dot structures. The dependence of the quantum dot level separation on dot size is in agreement with calculations of the strain-induced band edge modulation. For 200 nm wide carbon dot stressors the level separations are approximately 2 meV. Frustration of acceptor recombination by three-dimensional localization of carriers in the strain-induced potential wells is clearly observed. Finally, we detect luminescence from a single quantum dot at low excitation intensity, a result of the frustration of nonradiative recombination by localization.