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Lateral Aligment of Epitaxial Quantum Dots

TitleLateral Aligment of Epitaxial Quantum Dots
Publication TypeBook
Year of Publication2007
AuthorsO. Schmidt
Series TitleNano Science and Technology
Number of Pages691–707
PublisherSpringer Berlin Heidelberg
CityBerlin, Heidelberg
Keywords2007, Chemistry and Materials Science, Single Fellow

It is naturally of interest to extend the successful integration of quantum wells (QWs) in epitaxial semiconductor structures to more highly confined systems, such as quantum wires (QWRs) and quantum dots (QDs). However, the precision in the epitaxial crystal growth used to fabricate QWs is on the order of the crystal monolayer (ML), higher than the current lithography techniques that are required to form QWRs and QDs. In addition, in these more dimensionally reduced systems the surface area to volume ratio is increased, and poorly terminated surfaces, due to either exposed free surface or process-related damage, diminish the quality. Coupling these problems with the fact that typically only a few QWs are used together, while typically much more QDs will be required to achieve equivalent output power, it becomes clear why progress in this area has been slow. Crystal growth techniques have been used with varying success over the last decade to produce one- and zero-dimensional structures. Colloidal systems have produced QD ensembles [1] with inhomogeneous broadening and are difficult to integrate into epitaxial systems common to solid state devices. Regrowth on patterned substrates has been used to produce QWRs [2] and the patterned regions above QWs have been used as stressors to form QDs from the QW [3]. Finally, ensembles of QDs have been formed by strainenhanced surface diffusion [4], and ordering has been observed using the (311) surface [5].