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QUANTUM DOT SUPERLATTICES

   Figure 1: SEM image of Ge/Si quantum dots.


   Figure 3: Measured Hall mobility in doped
   Ge/Si quantum dot array at 77 K.
   After Y. Bao and A.A. Balandin, 2003.



   Figure 3: Intensity of phonon vibrations
   in Ge/Si cubic quantum dot crystal
   in ((010))) plane.



   Figure 4: Electronic density of states
   in tetragonal InAs/GaAs quantum dot crystal
   Lx=Ly=11nm, Lz=10nm Hx=Hy=Hz =5nm.
   After Lazarenkova and Balandin,
   J. Appl. Phys., 2001.


Sponsors:

National Science Foundation
Nanoscale Exploratory Research



Project Duration: 2002-2004


   Quantum dot superlattices (QDS) are potential candidates for the thermoelectric, photo-detector and photovoltaic applications. Strong coupling and regimentation in such structures leads to formation of 3D extended mini-bands instead of localized quantum dot states. This makes QDS analogous to artificial crystals, e.g. quantum dot crystals. Such energy spectrum modification is expected to take place provided that the dot size is homogeneous and the dots are crystalline with low surface defect concentration. The task addressed in this project is theoretical proof-of-concept investigation of requirements for achieving carrier mini-band transport regime and scattering suppression in quantum dot superlattices. Modification of acoustic phonon modes in quantum dot arrays due to spatial confinement and boundary scattering leads to a change in phonon dispersion and density of states. At the final stage of this research we carry out application specific structure optimization based on our model. New efficient thermoelectric quantum dot superlattices may have a tremendous impact on a wide range of energy needs due to their inherent advantages such as high reliability, light weight, compactness, quit operation, and environmental safety.





Relevant Publications:

* Thermoelectric figure-of-merit enhancement in quantum dot superlattices , (A.A. Balandin and O.L. Lazarenkova, Appl. Phys. Lett., 2003).

* Miniband formation in a quantum dot crystal,
(O.L. Lazarenkova and A.A. Balandin, J. Appl. Phys., 2001).



Disclaimer: Any opinions, findings, and conclusions or recommendations expressed in this web-site are those of the authors and do not necessarily reflect the views of the National Science Foundation.
 
 
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