Acoustic phonon emission by optically excited carriers in the InAs/GaAs quantum dot system

The phonons emitted by photoexcited carriers in self-organised InAs quantum dots in GaAs have been studied using a time-resolved bolometric detection technique. Measurements of the temporal, excitation power and, for the firs t time, angular dependence of the phonon emission have been made. The resul ts show that carrier relaxation in the dots takes place mainly bp emission of sub-THz acoustic phonons. We suggest that the results can be explained b y considering the energy relaxation of excitons instead of treating the ele ctrons and holes separately.