Modulated reflectance study of InAs quantum dot stacks embedded in GaAs/AlAs superlattice

Optical transitions in vertically stacked InAs quantum dot (QD) superlattice (SL) with and without AlAs barriers were examined by photo- and electroreflectance techniques. The interband transitions corresponding to the QD, wetting layer (WL), and InAs/GaAs/AlAs SL have been identified. Experimental data and numerical calculations show that blueshifts and enhancement in the intensity of WL-related optical transitions in an InAs/GaAs/AlAs SL originate mainly due to off-center position of the QD layers in the quantum wells. The appearance of multiple WL-related features in the modulated reflectance spectra was revealed and discussed.