tailieunhanh - Báo cáo hóa học: " Multi-scale ordering of self-assembled InAs/GaAs(001) quantum dots"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Multi-scale ordering of self-assembled InAs/GaAs(001) quantum dots | Nanoscale Res Lett 2006 1 1-10 DOI S11671-006-9014-8 NANO REVIEW Multi-scale ordering of self-assembled InAs GaAs 001 quantum dots S. Kiravittaya R. Songmuang A. Rastelli H. Heidemeyer O. G. Schmidt Published online 25 July 2006 to the authors 2006 Abstract Ordering phenomena related to the selfassembly of InAs quantum dots QD grown on GaAs 001 substrates are experimentally investigated on different length scales. On the shortest length-scale studied here we examine the QD morphology and observe two types of QD shapes . pyramids and domes. Pyramids are elongated along the 1-10 directions and are bounded by 137 facets while domes have a multi-facetted shape. By changing the growth rates we are able to control the size and size homogeneity of freestanding QDs. QDs grown by using low growth rate are characterized by larger sizes and a narrower size distribution. The homogeneity of buried QDs is measured by photoluminescence spectroscopy and can be improved by low temperature overgrowth. The overgrowth induces the formation of nanostructures on the surface. The fabrication of selfassembled nanoholes which are used as a template to induce short-range positioning of QDs is also investigated. The growth of closely spaced QDs QD molecules containing 2-6 QDs per QD molecule is discussed. Finally the long-range positioning of selfassembled QDs which can be achieved by the growth on patterned substrates is demonstrated. Lateral QD replication observed during growth of three-dimensional QD crystals is reported. Keywords Self-assembly Semiconductor quantum dots Photoluminescence S. Kiravittaya El R. Songmuang A. Rastelli H. Heidemeyer O. G. Schmidt Max-Planck-Institut fur Festkorperforschung Heisenbergstrasse 1 D-70569 Stuttgart Germany e-mail Introduction Over the last decade semiconductor quantum dots QDs have attained much interest due to their electronic properties characterized by discrete atomic-like energy levels 1 2 . Nowadays .