The photoluminescence (PL) of InAs/GaAs heterostructures is investigated for InAs coverages, L, ranging from 0.6 to 3 monolayers (ML). For thin coverages (L ≤ 1.6 ML), we observe the recombination of heavy-hole excitons in InAs quantum dots (QDs) and in a 2D-InAs layer. The two PL bands shift toward low energy for increasing L. For L ≥ 1.6ML. the QD band shifts faster, while the exciton recombination in the 2D-layer vanishes. These results, confirmed by PL excitation and photoreflectivity, indicate that: a) QDs are interconnected by a two-dimensional InAs layer which allows an efficient carrier capture into the dots; b) the dot size increases with L, faster for L≥ 1.6 ML, at the expense of the 2D-layer. The peculiar temperature dependence of lizneshape and peak energy of the QD band is explained in terms of exciton thermal escape and relaxation mechanisms.
|Number of pages||5|
|Journal||Physica Status Solidi (A) Applied Research|
|Publication status||Published - Jan 1 1997|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics