Photoreflectance spectroscopy of vertically coupled InGaAs/GaAs double quantum dots

Photoreflectance and high excitation photoluminescence spectra have been measured at 10 K for In0.6Ga0.4As/GaAs double quantum dot structures with various thicknesses of the GaAs separating layer. Several transitions between split states, due to the dot–dot and wetting layer well–well interaction, have been observed. The transitions have been identified using the results of the effective mass approximation calculations for double quantum wells and lens-shaped double quantum dots. The splitting energy of the quantum dot transitions has been obtained as function of the GaAs barrier width.