As an ideal single-photon source, quantum dots (QDs) can play a unique role in the field of quantum information. Controlling QD exciton spontaneous emission can be achieved by anti-phase coupling between QD exciton dipole field and Au dipole field after QD film was transferred onto the Si substrate covered by Au nanoparticles. In the experiments, the studied InAs/GaAs QDs were grown by molecular beam epitaxy (MBE) on a (001) semi-insulation substrate. A film containing QDs with different GaAs thickness was separated from the GaAs substrate by etching away the AlAs sacrificial layer and transferred the QD film to the silicon wafer covered by Au nanoparticles with a diameter of 50 nm. The distance D (thickness of GaAs) from the surface of the Au nanoparticles to the QD layer is 10, 15, 19, 25, and 35 nm. A 640 nm pulsed semiconductor laser with a 40 ps pulse length was used to excite the QD samples for measuring QD exciton photoluminescence (PL) and time-resolved PL (TRPL) spectra at 5 K. It is found that when the distance D is 15-35nm the spontaneous emission rate of exciton is suppressed. And when D is close to 19 nm, the QD spontaneous emission rate decreases to ~10^(-3), which is consistent with the theoretical calculation. The physical mechanism of long-lived exciton luminescence observed in the experiment is due to the fact that Au nanoparticles scatter the light field of the exciton radiation in the QD wetting layer, and the phase of the scattered field is opposite to the phase of the exciton radiation field. Therefore, the destructive interference between the exciton radiation field and scattering field of Au nanoparticles results in long-lived exciton emission observed in the experiment.
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