Adatom condensation and quantum dot sizes in InGaAs/GaAs (001)

The sizes and concentrations of capped and surface InGaAs/GaAs quantum dots (QDs) grown under the same conditions have been investigated. Comparisons obtained with transmission electron microscopy and scanning probe microscop y imaging show a significant enlargement in the sizes of surface QDs compar ed with capped QDs. This discrepancy in dot dimensions increases with decre asing island surface densities and can be partially explained by thermal ad atom condensation during sample cooling. These findings suggest a technique to estimate adatom concentrations and their migration lengths in strained heteroepitaxy. (C) 2000 American Institute of Physics. [S0003-6951(00)03312 -X].