Volume (Eff. Bohr3)

Figure 60. Ground state energy for a hydrogenic impurity within quantum dots of a spherical and prolate spheroidal shape as a function of their volume for a fixed value of the barrier height. (a) V0 = 2.0R*, (b) V0 = 8.0R*. Reprinted with permission from [205], J. L. Marin et al., in "Handbook of Advanced Electronic and Photonic Materials and Devices" (H. S. Nalwa, Ed.). Academic Press, San Diego, 2001. © 2001, Academic Press.

In Figure 61a, we show the energy for the ground state of the hydrogenic impurity confined in a spherical quantum dot as a function of the volume, for V0 = 8.0 and 2.0 effective Rydbergs. In the solid curves, the Coulomb term is not included in the external region of the quantum dot while in the dashed ones we have considered it. Figure 61b shows the same curves as in Figure 61a for the prolate spheroidal quantum dot with R = 1.0 effective Bohr. A difference between the curves with and without the Coulomb term in the exterior of the quantum dot can be noticed. This difference is greater for the smaller barrier height potential and in the region of strong confinement regime (small sizes of the quantum dot). This effect is similar to that discussed earlier for Figure 60.

In Figure 62, we make a comparison of the ground state energy of the hydrogenic impurity confined within a prolate spheroidal quantum dot, for V0 = 2.0 effective Rydbergs and

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