C2v and D3h symmetric InAs quantum dots on GaAs (001) substrate: Exciton emission and a defect field influence

摘要

InAs/GaAs quantum dots (QDs) grown on a GaAs (001) substrate were studied by photoluminescence spectroscopy. Both Csub2v/sub and Dsub3h/sub QDs with featured XXsub11/sub, Xsub11/subsup+/sup, and XXsub21/subsup+/sup spectra have been found. A local defect field tunes the dominant exciton from Xsup+/sup to X or Xsup?/sup, enhances the population on XX, XXX, and XXXsup?/sup, and induces tunneling and spectral diffusion. In Dsub3h/sub QDs, it also induces a prior e sub1/sub– h sub2/sub transition and a structural polarization of XXsub21/subsup+/sup and XXsub11/sub to build a direct cascade XXsub21/subsup+/sup ? Xsup+/sup. Both XXsub21/subsup+/sup ? Xsup+/sup and XX ? X have no fine structure splitting, promising for entangled photon pair emission. A dominant Xsup+/sup with slow electron capture (due to background holes) proves a pure single-photon emission.