Anomalous coarsening of self-assembled InAs quantum dots on vicinal GaAs (100) substrates

The formation process of InAs quantum dots (QDs) on vicinal GaAs (1 0 0) substrates is studied by atomic force microscopy (AFM). It is found that after 1.2 MLs of InAs deposition, while the QDs with diameters less than the width of the multi-atomic steps are shrinking, the larger QDs are growing. Photoluminescence measurements of the uncapped QDs correspond well to the AFM structure observations of the QDs. We propose that the QDs undergo an anomalous coarsening process with modified growth kinetics resulting from the restrictions of the finite terrace sizes. A comparison between the QDs on the vicinal GaAs (1 0 0) substrates and the QDs on the exact GaAs (1 0 0) further verifies the effect of the multi-atomic steps on the formation of QDs.

60476009the National 973 Program of China 2006CB60490 2006CB604902 National 863 2006AA01Z256 The work was supported by the National Natural Science Foundation of China under Grant Nos 60706009, 60476009, the National 973 Program of China under Grant Nos 2006CB60490, 2006CB604902 and the National 863 project under Grant No 2006AA01Z256.