Abstract

Shape ellipticity dependence of the exciton fine energy levels in CdTe and CdSe nanocrystal quantum dots were compared theoretically by considering the crystal structure and the Coulomb interaction of an electron and a hole. While quantum dot ellipticity changes from an oblate to prolate quantum dot via spherical shape, both the fine energy levels and the dipole moment in wurtzite structure of a CdSe quantum dot change linearly for ellipticity. In contrast, CdTe quantum dots were found to show a level crossing between the bright and dark exciton states with a significant change of the dipole moment due to the cubic structure. Shape ellipticity dependence of the optical nonlinearities in CdTe and CdSe nanocrystal quantum dots was also calculated by using semiconductor Bloch equations. For a spherical shape quantum dot, only 1L dominates the optical nonlinearities in a CdSe quantum dot, but both 1U and 0U contribute in a CdTe quantum dot. As excitation pulse area becomes strong (~π), the optical nonlinearities of both CdSe and CdTe quantum dots are mainly governed by absorption saturation. However, in the case of a prolate CdTe quantum dot, the real part of the nonlinear refractive index becomes relatively significant.

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  12. V. I. KlimovNanocrystal quantum dotsCRC Press2010
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  14. E. O. KaneBand structure of indium antimonideJ. Phys. Chem. Solids19571249261
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  17. A. Rubio-Ponce, D. Olguin, and I. Hernandez-CalderonCalculation of the effective masses of 2-6 semiconductor compoundsSuperficies Vacio2003162628
  18. G. Fonthal, L. Tirado-Mejia, J. I. Marin-Hurtado, H. Ariza-Calderon, and J. G. Mendoza-AlvarezTemperature dependence of the band gap energy of crystalline CdTeJ. Phys. Chem. Solids200061579583
  19. M. Lindberg, R. Binder, and S. W. KochTheory of the semiconductor photon echoPhys. Rev. A19924518651875
  20. H. Haug and S. W. KochQuantum theory of the optical and electronic properties of semiconductorsWorld Scientific1990
  21. N. Van Trong and G. MahlerField-dependent screening and dephasing in semiconductor Bloch equationsPhys. Rev. B.19965417661774
  22. K.-C. Je, I.-C. Shin, J. Kim, and K. KyhmOptical nonlinearities of fine exciton states in a CdSe quantum dotAppl. Phys. Lett.201097103110

Other (22)

A. I. Ekimov, Al. L. Efros, and A. A. OnushchenkoQuantum size effect in semiconductor microcrystalsSolid State Commun.198556921924

Z.-W. Wang, W.-P. Li, J.-W. Yin, and J.-L. XiaoProperties of parabolic linear bound potential and coulomb bound potential quantum dot qubitCommun. Theor. Phys.200849311314

F. Pinaud, X. Michalet, L. A. Bentolila, J. M. Tsay, S. Doose, J. J. Li, G. Lyer, and S. WeissAdvances in fluorescence imaging with quantum dot bio-probesBiomaterials20062716791687

A. I. Ekimov, F. Hache, M. C. Schanne-Klein, D. Ricard, C. Flytzanis, I. A. Kudryavtsev, T. V. Yazeva, A. V. Rodina, and Al. L. EfrosAbsorption and intensity-dependent photoluminescence measurements on CdSe quantum dots:assignment of the first electronic transitionsJ. Opt. Soc. Am. B.199310100107

B. De Geyter and Z. HensThe absorption coefficient of PbSe/CdSe core/shell colloidal quantum dotsAppl. Phys. Lett.201097161908

A. Gaur, B. D. Shrivastava, and H. L. NigamX-Ray absorption fine structure (XAFS) spectroscopy - A reviewProc. Indian. Natn. Sci. Acad.201379921966

H. PingEffect of dielectric constant on the exciton ground state energy of CdSe quantum dotsChin. Phys.20009844847

S. W. Koch, N. Peyghambarian, and M. LindbergTransient and steady-state optical nonlinearities in semiconductorsJ. Phys. C: Solid State Phys.19882152295249

Al. L. EfrosLuminescence polarization of CdSe microcrystalsPhys. Rev. B.19914674487458

Al. L. Efros and A. V. RodinaBand-edge absorption and luminescence of nonspherical nanometer-size crystalsPhys. Rev. B.1996471000510007

Al. L. Efros, M. Rosen, M. Kuno, M. Nirmal, D. J. Norris, and M. BawendiBand-edge exciton in quantum dots of semiconductors with a degenerate valence band: Dark and bright exciton statesPhys. Rev. B.19965448434856

V. I. KlimovNanocrystal quantum dotsCRC Press2010

D. J. Norris and M. G. BawendiMeasurement and assignment of the size-dependent optical spectrum in CdSe quantum dotsPhys. Rev. B.1995531633816346

E. O. KaneBand structure of indium antimonideJ. Phys. Chem. Solids19571249261

C. R. Pidgeon and R. N. BrownInterband magneto-absorption and faraday rotation in InSbPhys. Rev.1966146575583

M. Nirmal, D. J. Norris, M. Kuno, M. G. Bawendi, Al. L. Efros, and M. RosenObservation of the “Dark exciton” in CdSe quantum dotsPhys. Rev. Lett.19957537283731

A. Rubio-Ponce, D. Olguin, and I. Hernandez-CalderonCalculation of the effective masses of 2-6 semiconductor compoundsSuperficies Vacio2003162628

G. Fonthal, L. Tirado-Mejia, J. I. Marin-Hurtado, H. Ariza-Calderon, and J. G. Mendoza-AlvarezTemperature dependence of the band gap energy of crystalline CdTeJ. Phys. Chem. Solids200061579583

M. Lindberg, R. Binder, and S. W. KochTheory of the semiconductor photon echoPhys. Rev. A19924518651875

H. Haug and S. W. KochQuantum theory of the optical and electronic properties of semiconductorsWorld Scientific1990

N. Van Trong and G. MahlerField-dependent screening and dephasing in semiconductor Bloch equationsPhys. Rev. B.19965417661774

K.-C. Je, I.-C. Shin, J. Kim, and K. KyhmOptical nonlinearities of fine exciton states in a CdSe quantum dotAppl. Phys. Lett.201097103110

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