Dynamic photon emission from multiphoton-excited semiconductor quantum dots
2008 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 103, no 9, 093703-1-093703-6 p.Article in journal (Refereed) Published
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 Schrodinger 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 ultrafast pulsed laser, whose photon energy is below the QD band gap, also induces a similar narrow but weaker emission peak, which results in a nonstrict 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.
Place, publisher, year, edition, pages
2008. Vol. 103, no 9, 093703-1-093703-6 p.
Electronic states; Laser pulses; Monte Carlo methods; Multiphoton processes; Photoexcitation; Semiconductor quantum dots; Valence bands; Optical emission spectra; Photon emission
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-8233DOI: 10.1063/1.2908187ISI: 000255983200072ScopusID: 2-s2.0-43949113666OAI: oai:DiVA.org:kth-8233DiVA: diva2:13498
QC 20100730. Uppdaterad från in press till published (20100730).2008-04-182008-04-182010-07-30Bibliographically approved