Existence of a phonon bottleneck for excitons in quantum dots

Abstract

A phonon bottleneck is manifested for correlated electron/hole (exciton) states in self-organized ${\mathrm{In}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}/\mathrm{GaAs}$ 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 $\ensuremath{\sim}7.7 \mathrm{ns},$ being $\ensuremath{\sim}15$ times the radiative lifetime, is attributed to a quenched polar exciton-LO-phonon coupling in truncated QD's based on eight-band $\mathbf{k}\ensuremath{\cdot}\mathbf{p}$ model calculations.