Exciton–Acoustic Phonon Coupling in Single CdTe Quantum Dots

Abstract

The photoluminescence spectra of individual quantum dots have been measured with high spectral and spatial resolution spectroscopy. The temperature dependence of the line broadening is analyzed for different single-confined excitons. At low temperatures, the photoluminescence spectra can be very well fitted by a Lorentzian, as expected from the lifetime broadening and the pure dephasing described by a linear phase damping. However, surprisingly, when increasing the temperature, the line shape progressively deviates from a Lorentzian and an additional broad background is observed. This non-Lorentzian line shape and its temperature dependence are theoretically modeled on the basis of lattice relaxation due to the exciton–acoustic phonon coupling.