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Superlattices: problems and new opportunities, nanosolids.

Tsu R - Nanoscale Res Lett (2011)

Bottom Line: Superlattice is simply a way of forming a uniform continuum for whatever purpose at hand.However, new opportunities in component-based nanostructures may lead the field of endeavor to new heights.The all important translational symmetry of solids is relaxed and local symmetry is needed in nanosolids.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of North Carolina at Charlotte, Charlotte, NC 28223 USA. Tsu@uncc.edu.

ABSTRACT
Superlattices were introduced 40 years ago as man-made solids to enrich the class of materials for electronic and optoelectronic applications. The field metamorphosed to quantum wells and quantum dots, with ever decreasing dimensions dictated by the technological advancements in nanometer regime. In recent years, the field has gone beyond semiconductors to metals and organic solids. Superlattice is simply a way of forming a uniform continuum for whatever purpose at hand. There are problems with doping, defect-induced random switching, and I/O involving quantum dots. However, new opportunities in component-based nanostructures may lead the field of endeavor to new heights. The all important translational symmetry of solids is relaxed and local symmetry is needed in nanosolids.

No MeSH data available.


Related in: MedlinePlus

A Model for the enhanced coupling between QDs from adjacent QDs. Top shows singly occupied individual QDs, middle shows doubly occupied QDs, and bottom shows exchanging occupations leading to oscillations generally fast oscillations. When a trap serves as an imposter of a QD, telegraph-like slow oscillation occurs [19].
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Figure 4: A Model for the enhanced coupling between QDs from adjacent QDs. Top shows singly occupied individual QDs, middle shows doubly occupied QDs, and bottom shows exchanging occupations leading to oscillations generally fast oscillations. When a trap serves as an imposter of a QD, telegraph-like slow oscillation occurs [19].

Mentions: We now basically understood this telegraph-like noise. Figure 4 shows how QDs are coupled together much the same way as molecules. Whenever two adjacent QDs are occupied, the self-consistent potential moves up at the expense of the barrier separating them. This process goes on as the dots are coupled in forming two-dimensional sheets until something happens; no dots are within the coupling range. The wave function of the QDs is affected by strong coupling with that of the defects, even for defects located relatively far from the locations of the dots, strong 1/f noise, commonly known as telegraph noise appears. In fact this type of problem even occurs in optical properties of QDs, blinking in emission [19]. One may argue that this switching is due to very large defects of a Si matrix, these Si nanocrystals are embedded. My view is that reducing these defects is possible, but eliminating them is not possible.


Superlattices: problems and new opportunities, nanosolids.

Tsu R - Nanoscale Res Lett (2011)

A Model for the enhanced coupling between QDs from adjacent QDs. Top shows singly occupied individual QDs, middle shows doubly occupied QDs, and bottom shows exchanging occupations leading to oscillations generally fast oscillations. When a trap serves as an imposter of a QD, telegraph-like slow oscillation occurs [19].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211173&req=5

Figure 4: A Model for the enhanced coupling between QDs from adjacent QDs. Top shows singly occupied individual QDs, middle shows doubly occupied QDs, and bottom shows exchanging occupations leading to oscillations generally fast oscillations. When a trap serves as an imposter of a QD, telegraph-like slow oscillation occurs [19].
Mentions: We now basically understood this telegraph-like noise. Figure 4 shows how QDs are coupled together much the same way as molecules. Whenever two adjacent QDs are occupied, the self-consistent potential moves up at the expense of the barrier separating them. This process goes on as the dots are coupled in forming two-dimensional sheets until something happens; no dots are within the coupling range. The wave function of the QDs is affected by strong coupling with that of the defects, even for defects located relatively far from the locations of the dots, strong 1/f noise, commonly known as telegraph noise appears. In fact this type of problem even occurs in optical properties of QDs, blinking in emission [19]. One may argue that this switching is due to very large defects of a Si matrix, these Si nanocrystals are embedded. My view is that reducing these defects is possible, but eliminating them is not possible.

Bottom Line: Superlattice is simply a way of forming a uniform continuum for whatever purpose at hand.However, new opportunities in component-based nanostructures may lead the field of endeavor to new heights.The all important translational symmetry of solids is relaxed and local symmetry is needed in nanosolids.

View Article: PubMed Central - HTML - PubMed

Affiliation: University of North Carolina at Charlotte, Charlotte, NC 28223 USA. Tsu@uncc.edu.

ABSTRACT
Superlattices were introduced 40 years ago as man-made solids to enrich the class of materials for electronic and optoelectronic applications. The field metamorphosed to quantum wells and quantum dots, with ever decreasing dimensions dictated by the technological advancements in nanometer regime. In recent years, the field has gone beyond semiconductors to metals and organic solids. Superlattice is simply a way of forming a uniform continuum for whatever purpose at hand. There are problems with doping, defect-induced random switching, and I/O involving quantum dots. However, new opportunities in component-based nanostructures may lead the field of endeavor to new heights. The all important translational symmetry of solids is relaxed and local symmetry is needed in nanosolids.

No MeSH data available.


Related in: MedlinePlus