Abstract
A different approach to determining the wetting layer thickness and composition in quantum dot systems is proposed. This method combines the energy separation between heavy and light hole states determined experimentally and the results of a simple envelope function calculation to unambiguously obtain the wetting layer parameters. The heavy and light hole states are probed by photoluminescence excitation, but the proposed method can be extended to all absorptionlike measurements. For quantum dots, an effective wetting layer thickness of 3.6 monolayers and an average indium composition of 43% are obtained, in good agreement with results of structural characterization. Moreover, the optical transitions for InAs quantum dots covered by a thick (Ga,In)As cap layer with indium content up to 20% have also been probed. Several transitions resulting from the quantum well formed by the wetting layer and the cap layer have been detected. Using the wetting layer parameters deduced for quantum dots, the calculated , , , and transition energies correspond very well with the peak energies of the photoluminescence excitation spectra.
- Received 20 April 2007
DOI:https://doi.org/10.1103/PhysRevB.76.075335
©2007 American Physical Society