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.
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.
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).