Contactless electroreflectance studies of II-VI nanostructures grown by molecular beam epitaxy

The interband transitions of a single quantum well structure of Zn0.53Cd0.47Se/Zn0.27Cd0.23Mg0.50Se, lattice matched to InP, and of a capped CdSe quantum dot structure have been investigated using contactless electroreflectance. From a comparison of the quantum well optical transitions with those calculated using the envelope function approximation we determined the band offsets for this system. The electroreflectance spectrum of the quantum dot structure shows transitions originating from all the portions of the sample including the quantum dots and the wetting layer. Assuming a lens shape geometry and that the effective height-to-radius ratio observed in uncapped quantum dots is preserved, the size of the capped quantum dots was determined using the observed electroreflectance transitions, and the effective mass approximation.