EPITAXIAL GROWTH AND REAL-TIME ELECTRON DIFFRACTION ANALYSIS OF ADVANCED III-V SEMICONDUCTOR-BASED QUANTUM DOTS
The impact of growth kinetics on structural properties significantly affects optical and electronic performances of self-assembled Stranski-Krastanov (SK) quantum dots. Here and within the framework of the synthesis of archetype InAs/GaAs quantum dot system we have undertaken a systematic study on the evolution of dot facet orientation in terms diffraction characterization by the reflection high-energy electron diffraction (RHEED) technique. The existence of a sharp transition of facet arrangements and shapes near the onset of dot formation is investigated, and a dot structure bound by {2 5 11} facets is proposed. During further calculations, we observed asymmetric ripening of quantum dot facets at initial growth stages, and as the dot ripens, more symmetric facet arrangement to the incident direction was noted. Further, incorporating the correlation between dot structural properties and RHEED intensity features, we propose structures for quantum dots bounded by {1 3 6} and {1 (3 ) ̅5} facets for both asymmetric and symmetric situations. In addition, development of advanced quantum dot structures to fabricate wetting layer separated InAs quantum dots is implemented. Improvement of photoluminescence emission from InAs quantum dots embedded in a GaAs matrix is presented at the end of the work.
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