Time-resolved measurement of phonon bottleneck in self-organized quantum dot relaxation

Summary form only given. A "phonon bottleneck," or a suppression of carrier relaxation rates, is predicted for semiconductor self-assembled quantum dots because single-phonon-mediated scattering processes will be inhibited due to energy and momentum conservation requirements. However, many groups, including our own, observed fast interlevel relaxation and attributed it to Auger-type processes, intradot electron-hole scattering, or multi-phonon processes. We observe the bottleneck when we remove all of these fast relaxation processes by performing a differential transmission (DT) carrier capture experiment at low carrier densities. The sample is an undoped heterostructure with four layers of In/sub 0.4/Ga/sub 0.6/As quantum dots grown by molecular beam epitaxy.