Figure 7.1. Schematic plot of the single particle energy spectrum in a bulk
semiconductor for both the electron and hole states on the left side of the
panel with appropriate electron (e) and hole (h) discrete quantum states
shown on the right. The upper parabolic band is the conduction band, the
lower the valence.
Figure 7.2. Solutions of quantum dots of varying size. Note the variation
in color of each solution illustrating the particle size dependence of the
optical absorption for each sample. Note that the smaller particles are in
the red solution (absorbs blue), and that the larger ones are in the blue
(absorbs red).
Figure 7.3. La Mer model for the growth stages of nanocrystals.
Figure 7.4. Synthetic apparatus for the preparation of nanocrystals.
CH3(CH2)i-- (OCH2CH2)j-OH
- + - +
+ + - - + + + - + +
+
- +
-
H2S
Figure 7.5. Schematic for how cluster precipitation can occur in solution
from an inverse micel. Cluster size is regulated by micel size
(concentration).
Figure 7.6. Atomic Force Microscope images of Ge clusters on two types
of surfaces. Graphite in the left two panels, and SiO2 in the right. The line
plots on the figure give vertical profiles of line cuts through the AFM
images directly above and give the quantitative size information.
Figure 7.7. Illustration of high-energy ion implantation process to
fabricate quantum dots.
Figure 7.8. Illustration of a cross sectional view of Si quantum dots
formed in a glass matrix via ion implantation. Note that the random
arrangement and spherical shape of the quantum dot particles is
expected for quantum dots implanted in an amorphous media.
Figure 7.9. Photoluminescence spectra from Si (400 keV, 1.53 x
1017 cm-2) implanted SiO2 as implanted and after annealing at 950
and 1100 °C. (From Ref. 4 by permission of the American Institute
of Physics.)
Figure 7.10. Scanning electron micrograph of quantum dot patterns on a
GaSb surface induced by Ar-ion sputtering with an ion energy of 500 eV.
The dots show a hexagonal ordering with a characteristic wavelength that
depends on ion energy. The insets show the corresponding distribution of
the nearest-neighbor distance. (From Ref. 5 by permission of the
American Physical Society.)