Strain relaxation-induced modifications of the optical properties of self-assembled InAs quantum dot superlattices

We have investigated self-assembled InAs quantum dot superlattices using ph otoluminescence and transmission electron microscopy. We report results reg arding the influence of the dot vertical separation on the optical properti es of such structures. The photoluminescence peak shifts toward higher ener gies and its intensity drops by one order of magnitude when the distance be tween two consecutive quantum dot layers is reduced below 70 Angstrom. Our transmission electron microscopy images suggest that such unexpected photol uminescence features are related to the formation of structural defects ind uced by the large amount of strain relieved at small dot separations. (C) 2 000 American Vacuum Society. [S0734-211X(00)07303-0].