Existence of a phonon bottleneck for excitons in quantum dots

A phonon bottleneck is manifested for correlated electron/hole (exciton) states in self-organized ${\mathrm{In}}_x{\mathrm{Ga}}_{1-x}\mathrm{As}/\mathrm{GaAs}$ quantum dots (QD’s) with a flat, truncated shape. Suppressed relaxation and hot luminescence from excited states in the low-density regime are demonstrated. The long low-temperature relaxation time of $\sim 7.7\hspace{0.5em}\mathrm{ns},$ being $\sim 15$ times the radiative lifetime, is attributed to a quenched polar exciton-LO-phonon coupling in truncated QD’s based on eight-band $\mathbf{k}\cdot \mathbf{p}$ model calculations.