Self-organized growth of three-dimensional IV-VI semiconductor quantum dotcrystals with fcc-like vertical stacking and tunable lattice constant

Heteroepitaxial growth of highly lattice-mismatched semiconductor layers ha s evolved as a novel method for direct synthesis of self-assembled quantum dots based on the Stranski-Krastanov growth mode. In this growth mode, nano scale three-dimensional (3D) islands are spontaneously formed on the epitax ial surface once the layer thickness exceeds a certain critical coverage. I n multilayer structures, the interaction of the strained islands via their long-range elastic strain fields may lead to a vertical and lateral orderin g of the dots. Here, it is shown that the elastic anisotropy and the growth orientation play a crucial role for this self-organization process. In par ticular, for(111)-oriented IV-VI semiconductor (PbSe/Pb1-xEuxTe) multilayer s, the direction of the interlayer dot correlations is shown to be inclined to the surface normal. This leads to a fee-like ABCABC... vertical dot sta cking sequence, which is particularly effective for inducting a lateral ord ering of the dots as well. As a result, large domains of trigonally ordered 3D quantum dot crystals are formed, and their lattice constant can be tune d continuously just by changing the thickness of the spacer between the qua ntum dot layers. (C) 2000 Elsevier Science B.V. All rights reserved.