Strain plays a major role in fabrication of self-assembled quantum dots. In spite of the large number of growth studies, however, the role of the sign and absolute value of strain has remained a controversial issue (1). To shed light on this issue, in the present work we have compared the growth of ternary PbSeTe quantum dots on either PbSe or PbTe (111) surfaces, by which the deposited quantum dots are either under compressive, respectively, tensile strain. In addition, the absolute strain value was varied between 2 and 5.4% by changing the PbSeTe layer composition. From systematic in situ reflection high-energy electron diffraction as well as ex situ atomic force microscopy investigations complete phase diagrams of het-eroepitaxial growth were deduced for compressively as well as tensile strained structures. In agreement with recent theoretical calculations (2), we find quite similar critical wetting layer thicknesses in both cases, increasing from 2 monolayers to about 4 monolayers when the lat-tice mismatch is decreased from 5.4 to 2%, and a transition to a pure 2D layer-by-layer growth mode at even lower strain values. However, the size and density of the dot vastly dif-fers for the compressively versus tensily strained dots. This shows that while the sign of the strain does not alter the basic growth behavior it strongly changes the surface kinetics.
(1) Y. H. Xie, et. al., Phys. Rev. Lett. 73, 3006 (1994).
(2) Y. Tu and J. Tersoff, Phys. Rev. Lett. 93, 216101 (2004).
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