AFM characterization of PbTe quantum dots grown by molecular beam epitaxy under Volmer-Weber mode

PbTe quantum dots (QD) were fabricated on BaF2(1 1 1) substrates by molecular beam epitaxy under Volmer-Weber (V-W) growth mode. The morphological aspects of the samples were characterized using atomic force microscopy-AFM. In contrast to other reports dealing with QD grown under V-W mode, the uniformity of size distribution is comparable to that obtained for QD systems grown under Stransky-Krastanov mode. Furthermore, the observed QD density is consistent, at comparable surface coverages and growth temperatures. with previously reported values for other QD systems. Also, as growth proceeds, an increase in both material incorporation efficiency and in QD aspect ratio have been observed. Finally, the highest aspect ratio islands are found to be faceted, indicating possible changes in QD morphology as more material is incorporated into them. These results show that the V-W growth mode can be successfully used to obtain self-assembled quantum dots. (C) 2001 Elsevier Science B.V. All rights reserved.