Phonons and exciton recombination in CdSe/ZnSe self-assembled quantum dots

Abstract

We report resonant photoluminescence from CdSe/ZnSe self-assembled quantum dots. When CdSe quantum dots are resonantly excited, excitonic sharp micro-photoluminescence peaks originating from individual quantum dots are strongly enhanced in the region corresponding to optical phonon energies below the excitation. The phonons active in this process are identified as the longitudinal optical ͑LO͒ phonons from the CdSe dots, as the interface phonons, and tentatively as the LO phonons from the two-dimensional-like precursor layers. These observations suggest that exciton recombination via phonons is a major relaxation process under resonant excitation.

Influence of the Quantum Island Distribution on Relaxation of Localized Excitons in CdSe/ZnSe Heterostructures

“…Concerning the low temperatures, T€ urck et al [10] also observed a carrier feeding by means of a phonon-assisted tunneling from deep level states in the barrier into the quantum dots. Furthermore, our energy distance of 25 meV between the repeated energetic states is consistent with the observations of Rho et al [11]: They evaluated the LO-phonon energy to 27.3 meV in case of a CdSe quantum dot and to 23 meV for a 2D-like CdSe island.…”

Temperature dependence of photoluminescence bands inZn1−xCdxSKlochikhin1, Reznitsky2, Don3 et al. 2004Phys. Rev. B

“…This mechanism is similar to that used early to explain the disappearance of the narrow lines out of the -PL spectra. 5,23,27,44,50 The structure of the paper is as follows. In Sec.…”

Quasi-Stranski–Krastanow growth mode of self-assembled CdTe quantum dots grown on ZnSe by molecular beam epitaxy

“…The first and second longitudinal-optical (LO) phonon replicas are clearly defined. The energy difference adjacent pairs of 0LO-CdSe, 1LO-CdSe, and 2LO-CdSe is about 33 meV, which exceeds the LO phonon energy of bulk CdSe (25 meV) [17], because the compressive strain at the interface of CdTe and ZnSe increases the LO phonon energy [18]. However, when the coverage is increased to 5.0 MLs, the CdSe-precursor emission disappears.…”