The optical properties of In 0.5Ga 0.5As-GaAs single-layer quantum dots (SL-QDs) and three vertically stacked double-layer quantum dots (DL-QDs) with different spacer thicknesses, grown by solid-source molecular beam epitaxy (MBE) in Stranski-Krastonow (S-K) growth mode, are investigated by micro-photoluminescence (μ-PL) spectroscopy. Interestingly, μ-PL spectra of all DL-QDs are observed at energies lower by approximately 40 meV, compared with those of SL-QDs, indicating the effective coupling of DL-QDs, along with multiple sub-peaks on the right shoulder of the luminescence center. A reduction in overall energies of the quantum dot (QD) in terms of electronic coupling, and the creation of multiple energy states in terms of mutual interactions among the DL-QDs of different sizes and shapes, are considered to be possible reasons for this phenomenon. The excitation-power- dependent μ-PL spectra also show state-filling effects in the lowest energy levels of the DL-QDs.
|Number of pages||4|
|Journal||Journal of the Korean Physical Society|
|Publication status||Published - 2004 Jul|
- Molecular beam epitaxy
- Quantum dot
ASJC Scopus subject areas
- Physics and Astronomy(all)