THEORETICAL-ANALYSIS OF THE STRAIN RELAXATION IN QUANTUM-WELLS GROWN ON SEMICONDUCTOR SUPERLATTICES

We have studied the strain relaxation in several CdTe-based heterostru ctures. The systems consist on quantum wells grown up on the cleaved f ace of a strained superlattice. Photoluminescence studies in these sys tems show shifts towards larger energies. Such a shift can be interpre ted as due to the occurrence of quantum wires in the quantum well regi on. These quantum wires would result from additional confinement induc ed by the superlattice modulated strain. In order to check this propos al, we have studied the strain relaxation using the valence force fiel d model. In all cases, we have found that the strain induced by the su perlattice decays very rapidly from the cleaved interface to the surfa ce. In the quantum well region, the strained modulation has completely vanished. Our study thus demonstrates that quantum wires cannot be cr eated in the quantum well for the system modelised here.