SELF-FORMED INGAAS GAAS QUANTUM-DOT SUPERLATTICE AND DIRECT OBSERVATION ON STRAIN DISTRIBUTION IN THE CAPPED SUPERLATTICE/

We have demonstrated a 20 period dislocation-free InGaAs/GaAs quantum dot superlattice which is self-formed by the strain from the superlatt ice taken as a whole rather than by the strain from the strained singl e layer. The island formation does not take place while growing the co rresponding strained single layer. From the variation of the average d ot height in each layer, the strain distribution and relaxation proces s in the capped superlattice have been examined. It is found that the strain is not uniformly distributed and the greatest strains occur at two interfaces between the superlattice and the substrate and the cap layer in the capped superlattice. (C) 1997 American Institute of Physi cs.