Near-field spectroscopy of a single InGaAs self-assembled quantumdot

摘要

Relaxation mechanism of excited carriers in InGaAs-GaAsnself-assembled quantum dots has been investigated. Near-fieldnphotoluminescence excitation (PLE) spectra show some sharp resonancenlines whose energies match those of the LO phonons observed in far-fieldnPLE. The results suggest that the PLE resonant peaks are predominantlyndue to resonant Raman scattering from phonons. This assignment isnconsistent with the absence of magnetic field dependence of thenresonances. Single dot coherent spectroscopy shows the dephasing time ofnresonant carriers to be as fast as several tens of picoseconds. Thisnfast dephasing time agrees with the phonon-electron interactions beingnstrong. These results allow better understanding of the carriernrelaxation process in InGaAs-GaAs self-assembled quantum dots