Contactless electroreflectance of CdSe/ZnSe quantum dots grown by molecular-beam epitaxy

The interband transitions of a capped CdSe quantum-dot structure have been investigated using contactless electroreflectance. The electroreflectance spectrum shows transitions originating from all the portions of the sample including the quantum dots and the wetting layer. The transitions of the two-dimensional layers have been modeled using an envelope approximation calculation which takes into account the biaxial strain in the wetting layer. A good agreement was found between the experimental values for the transition energies and the calculated ones. From atomic force microscopy measurements, a lens shape was observed for the uncapped quantum dots. Taking into account the lens shape geometry and assuming that the effective height-to-radius ratio is preserved, the size of the capped quantum dots was determined using the observed electroreflectance transitions, in the framework of the effective mass approximation. (C) 2003 American Institute of Physics.