Abstract
We present a purely spectroscopic way to determine single-particle energy level splittings in individual InAs/GaAs QDs. The method is based on a combination of -photoluminescence spectroscopy with resonant excitation and -photoluminescence excitation spectroscopy of charged QDs. The approach allows elimination of all contributions from few-particle interactions such that true single-particle energy level distances are determined. For the present InAs/GaAs QDs, showing ground-state recombination energies between 1.23 to 1.27 eV, the splitting between the hole ground state and first excited state is . The splitting between the first and second excited hole states is . These values are in good agreement with results from eight-band calculations on lens-shaped InAs/GaAs QDs. Theoretical investigations identify unambiguously the heavy-hole-light-hole coupling as the decisive parameter leading to a nonzero splitting.
- Received 25 January 2009
DOI:https://doi.org/10.1103/PhysRevB.79.205321
©2009 American Physical Society