Excitons quantum dots

Nozik AJ (2008) Multiple exciton generation in semiconductor quantum dots. Chem Phys Lett 457 3-11... 

Abstreiter, G., Finley, J. J. and Zrenner, A. (2005) Recent advances in exciton-based quantum information processing in quantum dot nanostructures. New J. Phys., 7, 184-1-184-27. 

In addition to the photoluminescence red shifts, broadening of photoluminescence spectra and decrease in the photoluminescence quantum efficiency are reported with increasing temperature. The spectral broadening is due to scattering by coupling of excitons with acoustic and LO phonons [22]. The decrease in the photoluminescence quantum efficiency is due to non-radiative relaxation from the thermally activated state. The Stark effect also produces photoluminescence spectral shifts in CdSe quantum dots [23]. Large red shifts up to 75 meV are reported in the photoluminescence spectra of CdSe quantum dots under an applied electric field of 350 kVcm . Here, the applied electric field decreases or cancels a component in the excited state dipole that is parallel to the applied field the excited state dipole is contributed by the charge carriers present on the surface of the quantum dots. 

Figure 17.7 Schematic illustration of the decay routes of an exciton generated in CdSe-ZnS quantum dots Reprinted with permission from reference [31] copyright [2003], American Chemical Society.

G. (1994) Eluorescence-line narrowing in CdSe quantum dots - surface localization of the photogenerated exciton. Phys. Rev. B, 50, 2293-2300. 

New Solar Cells Quantum Dot (QD) Structures and Multiple Exciton Generation (MEG)... 

Luque, A. Marti, A. Nozik, A. J. 2007. Quantum dots Multiple exciton generation and intermediate bands. MRS Bull. 32 236-241. 

One can say that the obtained by us experimental results upon 2D exciton localization (taking place due to the growth of the crystal dielectric permeability anisotropy parameter) with o are very close to [27] where the behaviour of polaron excitons in parabolic quantum dots were considered and shown that the dot size decrease results in increasing the exciton binding energy. 

It has been proposed recently that phase separation of GalnN into In-rich and Ga-rich phases has profound consequences on the optical properties and on the lasing properties of GalnN/GaN/AlGaN quantum well heterostructures [1,2]. The nanoscale compositional fluctuations resulting from phase separation are believed to lead not only to exciton localisation [2] but even to a quantum-dot-like behaviour [3], A more detailed discussion of the microscopic aspects of phase separation is given elsewhere in this volume. 

Ideal semiconductor quantum dot structures should exhibit a delta-function-like (atomic-like) density-of-states for both electrons mid holes [4], Optical excitations in such structures are excitonic in nature, since an electron mid a hole confined in a quantum dot necessarily interact via their Coulomb interaction mid, therefore, form mi exciton. Consequently, a single electron-hole pair in a quantum dot corresponds to mi exciton, whereas doubly occupied electron and hole states (both spin states) correspond to a biexciton. Since the Coulomb interaction of the particles is inevitable, it makes no sense to distinguish between excitons mid free electrons mid holes within a quantum dot. Optical gain... 

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