Publication record
Dynamic photon emission from multiphoton-excited semiconductor
quantum dots
| Title | Dynamic photon emission from multiphoton-excited semiconductor
quantum dots |
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| Authors | T.-T. Han, Y. Fu and H. Ågren |
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| Citation | J. Appl. Phys, vol.103, p.93703(6), 2008. |
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| Doi: | |
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| Year | 2008 |
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| Field | Solid state electronics and photonics |
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| Section | Solid state electronics |
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| Sub-section | Nanoelectronics |
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| Keywords | multiphoton, quantum dots |
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| Abstract | The dynamic process of multiphoton optical transitions in
semiconductor quantum dots (QDs) has been studied by a Monte Carlo
scheme. The scheme includes optical transitions of all electrons,
initially occupying the valence-band confined states in the QD,
among the confined states in valence and conduction bands. The
optical transition probabilities are calculated by the
time-dependent Schrödinger equation and nonradiative
phonon-scattering processes have been included. Assisted by a
two-photon excitation by a continuous wave laser (one photon energy
equals half of the QD energy band gap), an assembly of the QDs shows
an emission peak around the band gap in the optical emission
spectrum, while an ultra fast pulsed laser, whose photon energy is
below the QD band gap, also induces a similar narrow but weaker
emission peak, which results in a non-strict multiphoton excitation
condition for many potential applications including biophotonics.
Extension of the theoretical study to the spherical
CdS/Cd0.5Zn0.5S/ZnS-multicoated CdSe QD has reproduced the
experimental absorption and multiphoton emission spectra. |
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