Effects of two-dimensional electron gas on the optical properties of InAs/GaAs quantum dots in modulation-doped heterostructures

摘要

The Shubnikov-de Haas data showed that the carrier density of two-dimensional electron gas (2DEG) in the GaAs active region containing InAs quantum dot (QD) arrays embedded between modulation-doped Al_(0.25)Ga_(0.75)As/GaAs heterostructures increased with increasing doping concentration in the modulation layer. The transmission electron microscopy images showed that the sizes of the self-assembled InAs vertically stacked QD arrays inserted in the GaAs did not change significantly with increasing carrier density of the 2DEG. The photoluminescence (PL) spectra showed that the peaks corresponding to the interband transitions from the ground electronic subband to the ground heavy-hole subband of the InAs QDs shifted to the higher energy side with increasing density of the 2DEG and that the full width at half maximum of the PL spectrum increased slightly with increasing density of the 2DEG.