Resonant optical excitation of longitudinal-optical phonons and intermixing in InAsAlAs single quantum dots

Excitations of a single InAsAlAs self-assembled quantum dot were investigated by photoluminescence excitation spectroscopy. Resonant absorption by longitudinal-optical (LO) phonons of the quantum dot and the barriers is observed. In particular, a resonance at 41 meV is attributed to the AlAs-like mode of InAlAs with low Al content. Our results represent a direct optical measure of the intermixing (estimated below 10%) in a single quantum dot. They also demonstrate that all LO phonons of this mixed quantum dot system couple to the exciton states. © 2008 American Institute of Physics