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9 September 2019 Investigation of various capping layer configuration on heterogeneously coupled SML on SK quantum dots heterostructure
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Hybrid coupled quantum dot (QD) structures have a high absorption coefficient along with the minimum cumulative strain in the heterostructure compared to that in the homogeneously coupled heterostructure of only Stranski-Krastanov (SK) QDs. Here, we are introducing a theoretical analysis of the hybrid heterostructure consisting of six submonolayer (SML) stacks above SK QDs with a various capping layer combinations. Sample A (InGaAs-InGaAs) has both SK and SML capping layers of InGaAs. Similarly, Sample B (InGaAsInAlGaAs), sample C (InAlGaAs-InGaAs), and sample D (InAlGaAs-InAlGaAs) have variations in the capping composition of SK and SML dots. The barrier thickness between SML stacks and SK dots is taken to be 7.5nm, and the capping layer thickness of the SK dot is 3nm. The number of SML stacks and barrier thickness has been optimized from our previous experimental work. Hydrostatic and biaxial strains of four samples are analyzed and compared. It has been found that sample D shows the lowest magnitude of hydrostatic strain in both SML and SK dots, suggesting better carrier confinement in both QDs. Moreover, Sample D has the highest biaxial strain in the SK dot indicating the maximum splitting of the valence band which leads to a lower band gap in the sample. Thus, after optimizing all the performance parameters, we found that Sample D could be the potential candidate for optoelectronic device applications.
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Pravin Raut, Rajkumar Ramavath, Jhuma Saha, Debabrata Das, Debiprasad Panda, and Subhananda Chakrabarti "Investigation of various capping layer configuration on heterogeneously coupled SML on SK quantum dots heterostructure", Proc. SPIE 11085, Low-Dimensional Materials and Devices 2019, 1108517 (9 September 2019);

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