Lifetime of Confined LO Phonons in Quantum Dots and Its Impact on Phonon Bottleneck Issue

Due to the anharmonicity of lattice forces, the confined LO phonon in semiconductor quantum dots decays into bulk acoustic phonons, which results in a weakly size-dependent finite lifetime of the LO phonons with a time scale of picoseconds. Noting that this time scale is much shorter than the typical carrier radiative recombination time of nanoseconds, we expect an interesting impact of the LO phonon decay on the carrier's energy relaxation in quantum dots, where the phonon bottleneck effect was predicted. Accordingly, by including the dissipative decay of the LO phonons and employing the Wigner-Weisskopf approach, we re-examine theoretically the bottleneck issue within an intrinsic phonon scattering mechanism. The calculated result shows a fast carrier relaxation rate higher than 1010 s-1 in a wide detuning range of tens of meV around the LO phonon energy, which differs significantly from the original phonon bottleneck prediction.