Abstract
This work systematically investigated the optical and structural properties of multilayerelectronic vertically coupled InAs/GaAs quantum dot (QDs) structures grown bymolecular beam epitaxy for long-wavelength applications. A significant energyblue-shift in the photoluminescence (PL) spectra from 30-period InAs/GaAs QDsstructures was observed as the GaAs spacer thickness was decreased. Transmissionelectron microscopy (TEM) and PL measurements indicated that the abnormalblue-shift can be attributed to the strain-driven In/Ga intermixing between QDs andspacer layers, which overcompensates for the effects of electronic and structuralcouplings between QD layers. Moreover, this study demonstrates that increasing thegrowth rate of InAs QDs can prevent intermixing. A PL emission wavelengthof 1320 nm with strong luminescence at room temperature, which correspondsto an energy red-shift of 50 meV from that of the single QD layer sample, wasachieved in a 10-period InAs/GaAs QD superlattice with a spacer thickness of 16 nm.
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