Phonons in InAs/AlAs single quantum dots observed by optical emission

Photoluminescence emission spectra of self-assembled single InAs/AlAs quantum dots with variable size reveal typical sharp lines below 1.8 eV, corresponding to transitions between fully confined states. Above this energy the sharp peaks disappear due to the IF-X scattering of conduction electrons. Excitation spectra of the biexciton line in single quantum dots show marked maxima at the optical-phonon frequency of the quantum dot and at its first overtone. The quantum dot phonon energy observed is 31 meV. Our results indicate an efficient polaron coupling in these quantum dots.