Strain distribution in self-assembled InP/GaInP quantum dots

Local strain on an atomic scale, as well as the size and the shape of InP q uantum dots (QDs) embedded in GaInP, have been measured directly from high- resolution electron microscopy images. There is a strong spatial variation in strain within a QD. A large part of the misfit strain is distributed in the GaInP matrix surrounding the QDs, especially in the case of small spaci ng between the QD layers. The strain distribution varies significantly with the thickness of the GaInP spacer layers between QD layers. The compressiv e strain within the QDs decreases with decreasing spacing between the QD la yers. This contributes to an increasing red shift of photoluminescence ener gy peak positions of QDs of multi-layers with decreasing thickness of the s pacer layers between the QD layers in comparison with that of single layer QDs. (C) 2000 American Institute of Physics. [S0021-8979(00)05414-1].